[#1661] Checkpoint: split server/client UTs

4 files changed, 2535 insertions, 71 deletions

diff --git a/src/lib/http/tests/Makefile.am b/src/lib/http/tests/Makefile.am
index 2e97f269fb..b69fcbc799 100644
--- a/src/lib/http/tests/Makefile.am
+++ b/src/lib/http/tests/Makefile.am
@@ -38,6 +38,8 @@ libhttp_unittests_SOURCES += response_unittests.cc
 libhttp_unittests_SOURCES += response_json_unittests.cc
 libhttp_unittests_SOURCES += run_unittests.cc
 libhttp_unittests_SOURCES += server_client_unittests.cc
+libhttp_unittests_SOURCES += tls_server_unittests.cc
+libhttp_unittests_SOURCES += tls_client_unittests.cc
 libhttp_unittests_SOURCES += url_unittests.cc
 libhttp_unittests_SOURCES += test_http_client.h
 
diff --git a/src/lib/http/tests/server_client_unittests.cc b/src/lib/http/tests/server_client_unittests.cc
index 48316b9c36..189b016023 100644
--- a/src/lib/http/tests/server_client_unittests.cc
+++ b/src/lib/http/tests/server_client_unittests.cc
@@ -500,9 +500,8 @@ public:
                             const HttpVersion& expected_version) {
         // Open the listener with the Request Timeout of 1 sec and post the
         // partial request.
-        TlsContextPtr context;
         HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS),
-                              SERVER_PORT, context,
+                              SERVER_PORT, TlsContextPtr(),
                               factory_, HttpListener::RequestTimeout(1000),
                               HttpListener::IdleTimeout(IDLE_TIMEOUT));
         ASSERT_NO_THROW(listener.start());
@@ -553,10 +552,9 @@ public:
             "{ }";
 
         // Use custom listener and the specialized connection object.
-        TlsContextPtr context;
         HttpListenerCustom<HttpConnectionType>
             listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                     context, factory_,
+                     TlsContextPtr(), factory_,
                      HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                      HttpListener::IdleTimeout(IDLE_TIMEOUT));
 
@@ -599,9 +597,8 @@ TEST_F(HttpListenerTest, listen) {
         "Content-Length: 3\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
     ASSERT_NO_THROW(listener.start());
@@ -631,9 +628,8 @@ TEST_F(HttpListenerTest, keepAlive) {
         "Connection: Keep-Alive\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
 
@@ -681,9 +677,8 @@ TEST_F(HttpListenerTest, persistentConnection) {
         "Content-Length: 3\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
 
@@ -733,10 +728,9 @@ TEST_F(HttpListenerTest, keepAliveTimeout) {
         "Connection: Keep-Alive\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     // Specify the idle timeout of 500ms.
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(500));
 
@@ -791,10 +785,9 @@ TEST_F(HttpListenerTest, persistentConnectionTimeout) {
         "Content-Length: 3\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     // Specify the idle timeout of 500ms.
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(500));
 
@@ -849,9 +842,8 @@ TEST_F(HttpListenerTest, persistentConnectionBadBody) {
         "Content-Length: 12\r\n\r\n"
         "{ \"a\": abc }";
 
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
 
@@ -895,9 +887,8 @@ TEST_F(HttpListenerTest, persistentConnectionBadBody) {
 
 // This test verifies that the HTTP listener can't be started twice.
 TEST_F(HttpListenerTest, startTwice) {
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
     ASSERT_NO_THROW(listener.start());
@@ -913,9 +904,8 @@ TEST_F(HttpListenerTest, badRequest) {
         "Content-Length: 3\r\n\r\n"
         "{ }";
 
-    TlsContextPtr context;
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
-                          context, factory_,
+                          TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
     ASSERT_NO_THROW(listener.start());
@@ -936,9 +926,8 @@ TEST_F(HttpListenerTest, badRequest) {
 // This test verifies that NULL pointer can't be specified for the
 // HttpResponseCreatorFactory.
 TEST_F(HttpListenerTest, invalidFactory) {
-    TlsContextPtr context;
     EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
-                              SERVER_PORT, context,
+                              SERVER_PORT, TlsContextPtr(),
                               HttpResponseCreatorFactoryPtr(),
                               HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                               HttpListener::IdleTimeout(IDLE_TIMEOUT)),
@@ -948,9 +937,8 @@ TEST_F(HttpListenerTest, invalidFactory) {
 // This test verifies that the timeout of 0 can't be specified for the
 // Request Timeout.
 TEST_F(HttpListenerTest, invalidRequestTimeout) {
-    TlsContextPtr context;
     EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
-                              SERVER_PORT, context, factory_,
+                              SERVER_PORT, TlsContextPtr(), factory_,
                               HttpListener::RequestTimeout(0),
                               HttpListener::IdleTimeout(IDLE_TIMEOUT)),
                  HttpListenerError);
@@ -959,9 +947,8 @@ TEST_F(HttpListenerTest, invalidRequestTimeout) {
 // This test verifies that the timeout of 0 can't be specified for the
 // idle persistent connection timeout.
 TEST_F(HttpListenerTest, invalidIdleTimeout) {
-    TlsContextPtr context;
     EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
-                              SERVER_PORT, context, factory_,
+                              SERVER_PORT, TlsContextPtr(), factory_,
                               HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                               HttpListener::IdleTimeout(0)),
                  HttpListenerError);
@@ -978,11 +965,10 @@ TEST_F(HttpListenerTest, addressInUse) {
     acceptor.open(endpoint.protocol());
     acceptor.bind(endpoint);
 
-    TlsContextPtr context;
     // Listener should report an error when we try to start it because another
     // acceptor is bound to that port and address.
     HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS),
-                          SERVER_PORT + 1, context, factory_,
+                          SERVER_PORT + 1, TlsContextPtr(), factory_,
                           HttpListener::RequestTimeout(REQUEST_TIMEOUT),
                           HttpListener::IdleTimeout(IDLE_TIMEOUT));
     EXPECT_THROW(listener.start(), HttpListenerError);
@@ -1099,11 +1085,10 @@ public:
         Url url("http://127.0.0.1:18123");
 
         // Initiate request to the server.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
         HttpResponseJsonPtr response1(new HttpResponseJson());
         unsigned resp_num = 0;
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1115,10 +1100,9 @@ public:
         }));
 
         // Initiate another request to the destination.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
         HttpResponseJsonPtr response2(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request2, response2,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1162,11 +1146,10 @@ public:
         Url url2("http://[::1]:18124");
 
         // Create a request to the first server.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
         HttpResponseJsonPtr response1(new HttpResponseJson());
         unsigned resp_num = 0;
-        ASSERT_NO_THROW(client.asyncSendRequest(url1, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url1, TlsContextPtr(),
                                                 request1, response1,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1178,10 +1161,9 @@ public:
         }));
 
         // Create a request to the second server.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
         HttpResponseJsonPtr response2(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url2, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url2, TlsContextPtr(),
                                                 request2, response2,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1220,10 +1202,9 @@ public:
         Url url("http://127.0.0.1:18125");
 
         // Create the first request.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
         HttpResponseJsonPtr response1(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [this](const boost::system::error_code& ec, const HttpResponsePtr&,
                    const std::string&) {
@@ -1244,10 +1225,9 @@ public:
         ASSERT_NO_THROW(runIOService(SHORT_IDLE_TIMEOUT * 2));
 
         // Create another request.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
         HttpResponseJsonPtr response2(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request2, response2,
             [this](const boost::system::error_code& ec, const HttpResponsePtr&,
                    const std::string&) {
@@ -1277,10 +1257,9 @@ public:
         Url url("http://127.0.0.1:18123");
 
         // Create the request.
-        TlsContextPtr context;
         PostHttpRequestJsonPtr request = createRequest("sequence", 1);
         HttpResponseJsonPtr response(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request, response,
             [this](const boost::system::error_code& ec,
                    const HttpResponsePtr&,
@@ -1306,7 +1285,6 @@ public:
         // Specify the URL of the server.
         Url url("http://127.0.0.1:18123");
 
-        TlsContextPtr context;
         // The response is going to be malformed in such a way that it holds
         // an invalid content type. We affect the content type by creating
         // a request that holds a JSON parameter requesting a specific
@@ -1314,7 +1292,7 @@ public:
         PostHttpRequestJsonPtr request = createRequest("requested-content-type",
                                                        "text/html");
         HttpResponseJsonPtr response(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request, response,
             [this](const boost::system::error_code& ec,
                    const HttpResponsePtr& response,
@@ -1346,7 +1324,6 @@ public:
 
         unsigned cb_num = 0;
 
-        TlsContextPtr context1;
         // Create the request which asks the server to generate a partial
         // (although well formed) response. The client will be waiting for the
         // rest of the response to be provided and will eventually time out.
@@ -1355,7 +1332,7 @@ public:
         // This value will be set to true if the connection close callback is
         // invoked upon time out.
         auto connection_closed = false;
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [this, &cb_num](const boost::system::error_code& ec,
                             const HttpResponsePtr& response,
@@ -1381,10 +1358,9 @@ public:
         );
 
         // Create another request after the timeout. It should be handled ok.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 1);
         HttpResponseJsonPtr response2(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request2, response2,
             [this, &cb_num](const boost::system::error_code& /*ec*/,
                             const HttpResponsePtr&,
@@ -1413,10 +1389,9 @@ public:
 
         unsigned cb_num = 0;
 
-        TlsContextPtr context;
         PostHttpRequestJsonPtr request = createRequest("sequence", 1);
         HttpResponseJsonPtr response(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request, response,
             [this, &cb_num](const boost::system::error_code& ec,
                             const HttpResponsePtr& response,
@@ -1443,7 +1418,7 @@ public:
         }));
 
         // Create another request after the timeout. It should be handled ok.
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request, response,
             [this, &cb_num](const boost::system::error_code& /*ec*/,
                             const HttpResponsePtr&,
@@ -1487,13 +1462,12 @@ public:
         Url url("http://127.0.0.1:18123");
 
         // Generate first request.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
         HttpResponseJsonPtr response1(new HttpResponseJson());
 
         // Use very short timeout to make sure that it occurs before we actually
         // run the transaction.
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [](const boost::system::error_code& ec,
                const HttpResponsePtr& response,
@@ -1508,10 +1482,9 @@ public:
         }, HttpClient::RequestTimeout(1)));
 
         if (queue_two_requests) {
-            TlsContextPtr context2;
             PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
             HttpResponseJsonPtr response2(new HttpResponseJson());
-            ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+            ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                     request2, response2,
                 [](const boost::system::error_code& ec,
                    const HttpResponsePtr& response,
@@ -1535,10 +1508,9 @@ public:
 
         // Now try to send another request to make sure that the client
         // is healthy.
-        TlsContextPtr context3;
         PostHttpRequestJsonPtr request3 = createRequest("sequence", 3);
         HttpResponseJsonPtr response3(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context3,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request3, response3,
                          [this](const boost::system::error_code& ec,
                                 const HttpResponsePtr&,
@@ -1568,13 +1540,12 @@ public:
         Url url("http://127.0.0.1:18123");
 
         // Initiate request to the server.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
         HttpResponseJsonPtr response1(new HttpResponseJson());
         unsigned resp_num = 0;
         ExternalMonitor monitor;
 
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1592,10 +1563,9 @@ public:
         ));
 
         // Initiate another request to the destination.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
         HttpResponseJsonPtr response2(new HttpResponseJson());
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request2, response2,
             [this, &resp_num](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1665,13 +1635,12 @@ public:
         Url url("http://127.0.0.1:18123");
 
         // Initiate request to the server.
-        TlsContextPtr context1;
         PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
         HttpResponseJsonPtr response1(new HttpResponseJson());
         unsigned resp_num = 0;
         ExternalMonitor monitor;
 
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request1, response1,
             [this, &client, &resp_num, &monitor](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1728,11 +1697,10 @@ public:
 
         // Now let's do another request to the destination to verify that
         // we'll reopen the connection without issue.
-        TlsContextPtr context2;
         PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
         HttpResponseJsonPtr response2(new HttpResponseJson());
         resp_num = 0;
-        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+        ASSERT_NO_THROW(client.asyncSendRequest(url, TlsContextPtr(),
                                                 request2, response2,
             [this, &client, &resp_num, &monitor](const boost::system::error_code& ec,
                               const HttpResponsePtr&,
@@ -1791,8 +1759,7 @@ public:
     public:
         /// @brief Constructor
         ExternalMonitor()
-            : registered_fd_(-1), connect_cnt_(0), handshake_cnt_(0),
-              close_cnt_(0) {
+            : registered_fd_(-1), connect_cnt_(0), close_cnt_(0) {
         }
 
         /// @brief Connect callback handler
@@ -1817,7 +1784,7 @@ public:
         /// @brief Handshake callback handler
         /// @param ec Error status of the ASIO connect
         bool handshakeHandler(const boost::system::error_code& ec, int) {
-            ++handshake_cnt_;
+            ADD_FAILURE() << "handshake callback handler is called";
             // ec indicates an error, return true, so that error can be handled
             // by Connection logic.
             return (true);
@@ -1840,9 +1807,6 @@ public:
         /// @brief Tracks how many times the connect callback is invoked.
         int connect_cnt_;
 
-        /// @brief Tracks how many times the handshake callback is invoked.
-        int handshake_cnt_;
-
         /// @brief Tracks how many times the close callback is invoked.
         int close_cnt_;
     };
diff --git a/src/lib/http/tests/tls_client_unittests.cc b/src/lib/http/tests/tls_client_unittests.cc
new file mode 100644
index 0000000000..dddb168727
--- /dev/null
+++ b/src/lib/http/tests/tls_client_unittests.cc
@@ -0,0 +1,1244 @@
+// Copyright (C) 2017-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include <config.h>
+#include <asiolink/asio_wrapper.h>
+#include <asiolink/interval_timer.h>
+#include <asiolink/tls_acceptor.h>
+#include <cc/data.h>
+#include <http/client.h>
+#include <http/http_types.h>
+#include <http/listener.h>
+#include <http/listener_impl.h>
+#include <http/post_request_json.h>
+#include <http/response_creator.h>
+#include <http/response_creator_factory.h>
+#include <http/response_json.h>
+#include <http/tests/response_test.h>
+#include <http/url.h>
+#include <util/multi_threading_mgr.h>
+
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <boost/pointer_cast.hpp>
+#include <gtest/gtest.h>
+
+#include <functional>
+#include <list>
+#include <sstream>
+#include <string>
+
+using namespace boost::asio::ip;
+using namespace isc::asiolink;
+using namespace isc::data;
+using namespace isc::http;
+using namespace isc::http::test;
+using namespace isc::util;
+namespace ph = std::placeholders;
+
+namespace {
+
+/// @brief IP address to which HTTP service is bound.
+const std::string SERVER_ADDRESS = "127.0.0.1";
+
+/// @brief IPv6 address to whch HTTP service is bound.
+const std::string IPV6_SERVER_ADDRESS = "::1";
+
+/// @brief Port number to which HTTP service is bound.
+const unsigned short SERVER_PORT = 18123;
+
+/// @brief Request Timeout used in most of the tests (ms).
+const long REQUEST_TIMEOUT = 10000;
+
+/// @brief Persistent connection idle timeout used in most of the tests (ms).
+const long IDLE_TIMEOUT = 10000;
+
+/// @brief Persistent connection idle timeout used in tests where idle connections
+/// are tested (ms).
+const long SHORT_IDLE_TIMEOUT = 200;
+
+/// @brief Test timeout (ms).
+const long TEST_TIMEOUT = 10000;
+
+/// @brief Test HTTP response.
+typedef TestHttpResponseBase<HttpResponseJson> Response;
+
+/// @brief Pointer to test HTTP response.
+typedef boost::shared_ptr<Response> ResponsePtr;
+
+/// @brief Generic test HTTP response.
+typedef TestHttpResponseBase<HttpResponse> GenericResponse;
+
+/// @brief Pointer to generic test HTTP response.
+typedef boost::shared_ptr<GenericResponse> GenericResponsePtr;
+
+/// @brief Implementation of the @ref HttpResponseCreator.
+class TestHttpResponseCreator : public HttpResponseCreator {
+public:
+
+    /// @brief Create a new request.
+    ///
+    /// @return Pointer to the new instance of the @ref HttpRequest.
+    virtual HttpRequestPtr
+    createNewHttpRequest() const {
+        return (HttpRequestPtr(new PostHttpRequestJson()));
+    }
+
+private:
+
+    /// @brief Creates HTTP response.
+    ///
+    /// @param request Pointer to the HTTP request.
+    /// @return Pointer to the generated HTTP response.
+    virtual HttpResponsePtr
+    createStockHttpResponse(const HttpRequestPtr& request,
+                            const HttpStatusCode& status_code) const {
+        // The request hasn't been finalized so the request object
+        // doesn't contain any information about the HTTP version number
+        // used. But, the context should have this data (assuming the
+        // HTTP version is parsed ok).
+        HttpVersion http_version(request->context()->http_version_major_,
+                                 request->context()->http_version_minor_);
+        // This will generate the response holding JSON content.
+        ResponsePtr response(new Response(http_version, status_code));
+        response->finalize();
+        return (response);
+    }
+
+    /// @brief Creates HTTP response.
+    ///
+    /// This method generates 3 types of responses:
+    /// - response with a requested content type,
+    /// - partial response with incomplete JSON body,
+    /// - response with JSON body copied from the request.
+    ///
+    /// The first one is useful to test situations when received response can't
+    /// be parsed because of the content type mismatch. The second one is useful
+    /// to test request timeouts. The third type is used by most of the unit tests
+    /// to test successful transactions.
+    ///
+    /// @param request Pointer to the HTTP request.
+    /// @return Pointer to the generated HTTP OK response with no content.
+    virtual HttpResponsePtr
+    createDynamicHttpResponse(HttpRequestPtr request) {
+        // Request must always be JSON.
+        PostHttpRequestJsonPtr request_json =
+            boost::dynamic_pointer_cast<PostHttpRequestJson>(request);
+        ConstElementPtr body;
+        if (request_json) {
+            body = request_json->getBodyAsJson();
+            if (body) {
+                // Check if the client requested one of the two first response
+                // types.
+                GenericResponsePtr response;
+                ConstElementPtr content_type = body->get("requested-content-type");
+                ConstElementPtr partial_response = body->get("partial-response");
+                if (content_type || partial_response) {
+                    // The first two response types can only be generated using the
+                    // generic response as we have to explicitly modify some of the
+                    // values.
+                    response.reset(new GenericResponse(request->getHttpVersion(),
+                                                       HttpStatusCode::OK));
+                    HttpResponseContextPtr ctx = response->context();
+
+                    if (content_type) {
+                        // Provide requested content type.
+                        ctx->headers_.push_back(HttpHeaderContext("Content-Type",
+                                                                  content_type->stringValue()));
+                        // It doesn't matter what body is there.
+                        ctx->body_ = "abcd";
+                        response->finalize();
+
+                    } else {
+                        // Generate JSON response.
+                        ctx->headers_.push_back(HttpHeaderContext("Content-Type",
+                                                                  "application/json"));
+                        // The body lacks '}' so the client will be waiting for it and
+                        // eventually should time out.
+                        ctx->body_ = "{";
+                        response->finalize();
+                        // The auto generated Content-Length header would be based on the
+                        // body size (so set to 1 byte). We have to override it to
+                        // account for the missing '}' character.
+                        response->setContentLength(2);
+                    }
+                    return (response);
+                }
+            }
+        }
+
+        // Third type of response is requested.
+        ResponsePtr response(new Response(request->getHttpVersion(),
+                                          HttpStatusCode::OK));
+        // If body was included in the request. Let's copy it.
+        if (body) {
+            response->setBodyAsJson(body);
+        }
+
+        response->finalize();
+        return (response);
+    }
+};
+
+/// @brief Implementation of the test @ref HttpResponseCreatorFactory.
+///
+/// This factory class creates @ref TestHttpResponseCreator instances.
+class TestHttpResponseCreatorFactory : public HttpResponseCreatorFactory {
+public:
+
+    /// @brief Creates @ref TestHttpResponseCreator instance.
+    virtual HttpResponseCreatorPtr create() const {
+        HttpResponseCreatorPtr response_creator(new TestHttpResponseCreator());
+        return (response_creator);
+    }
+};
+
+/// @brief Test fixture class for @ref HttpListener.
+class HttpListenerTest : public ::testing::Test {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// Starts test timer which detects timeouts.
+    HttpListenerTest()
+        : io_service_(), factory_(new TestHttpResponseCreatorFactory()),
+          test_timer_(io_service_), run_io_service_timer_(io_service_) {
+        test_timer_.setup(std::bind(&HttpListenerTest::timeoutHandler, this, true),
+                          TEST_TIMEOUT, IntervalTimer::ONE_SHOT);
+    }
+
+    /// @brief Callback function invoke upon test timeout.
+    ///
+    /// It stops the IO service and reports test timeout.
+    ///
+    /// @param fail_on_timeout Specifies if test failure should be reported.
+    void timeoutHandler(const bool fail_on_timeout) {
+        if (fail_on_timeout) {
+            ADD_FAILURE() << "Timeout occurred while running the test!";
+        }
+        io_service_.stop();
+    }
+
+    /// @brief Runs IO service with optional timeout.
+    ///
+    /// @param timeout Optional value specifying for how long the io service
+    /// should be ran.
+    void runIOService(long timeout = 0) {
+        io_service_.get_io_service().reset();
+
+        if (timeout > 0) {
+            run_io_service_timer_.setup(std::bind(&HttpListenerTest::timeoutHandler,
+                                                  this, false),
+                                        timeout, IntervalTimer::ONE_SHOT);
+        }
+        io_service_.run();
+        io_service_.get_io_service().reset();
+        io_service_.poll();
+    }
+
+    /// @brief IO service used in the tests.
+    IOService io_service_;
+
+    /// @brief Pointer to the response creator factory.
+    HttpResponseCreatorFactoryPtr factory_;
+
+    /// @brief Asynchronous timer service to detect timeouts.
+    IntervalTimer test_timer_;
+
+    /// @brief Asynchronous timer for running IO service for a specified amount
+    /// of time.
+    IntervalTimer run_io_service_timer_;
+};
+
+/// @brief Test fixture class for testing HTTP client.
+class HttpsClientTest : public HttpListenerTest {
+public:
+
+    /// @brief Constructor.
+    HttpsClientTest()
+        : HttpListenerTest(),
+          listener_(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                    TlsContextPtr(), factory_,
+                    HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                    HttpListener::IdleTimeout(IDLE_TIMEOUT)),
+          listener2_(io_service_, IOAddress(IPV6_SERVER_ADDRESS), SERVER_PORT + 1,
+                     TlsContextPtr(), factory_,
+                     HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                     HttpListener::IdleTimeout(IDLE_TIMEOUT)),
+          listener3_(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT + 2,
+                     TlsContextPtr(), factory_,
+                     HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                     HttpListener::IdleTimeout(SHORT_IDLE_TIMEOUT)) {
+        MultiThreadingMgr::instance().setMode(false);
+    }
+
+    /// @brief Destructor.
+    ~HttpsClientTest() {
+        listener_.stop();
+        listener2_.stop();
+        listener3_.stop();
+        io_service_.poll();
+        MultiThreadingMgr::instance().setMode(false);
+    }
+
+    /// @brief Creates HTTP request with JSON body.
+    ///
+    /// It includes a JSON parameter with a specified value.
+    ///
+    /// @param parameter_name JSON parameter to be included.
+    /// @param value JSON parameter value.
+    /// @param version HTTP version to be used. Default is HTTP/1.1.
+    template<typename ValueType>
+    PostHttpRequestJsonPtr createRequest(const std::string& parameter_name,
+                                         const ValueType& value,
+                                         const HttpVersion& version = HttpVersion(1, 1)) {
+        // Create POST request with JSON body.
+        PostHttpRequestJsonPtr request(new PostHttpRequestJson(HttpRequest::Method::HTTP_POST,
+                                                               "/", version));
+        // Body is a map with a specified parameter included.
+        ElementPtr body = Element::createMap();
+        body->set(parameter_name, Element::create(value));
+        request->setBodyAsJson(body);
+        try {
+            request->finalize();
+
+        } catch (const std::exception& ex) {
+            ADD_FAILURE() << "failed to create request: " << ex.what();
+        }
+
+        return (request);
+    }
+
+    /// @brief Test that two consecutive requests can be sent over the same
+    /// connection.
+    ///
+    /// @param version HTTP version to be used.
+    void testConsecutiveRequests(const HttpVersion& version) {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create a client and specify the URL on which the server can be reached.
+        HttpClient client(io_service_);
+        Url url("http://127.0.0.1:18123");
+
+        // Initiate request to the server.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        unsigned resp_num = 0;
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+            EXPECT_FALSE(ec);
+        }));
+
+        // Initiate another request to the destination.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                request2, response2,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+            EXPECT_FALSE(ec);
+        }));
+
+        // Actually trigger the requests. The requests should be handlded by the
+        // server one after another. While the first request is being processed
+        // the server should queue another one.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sure that the received responses are different. We check that by
+        // comparing value of the sequence parameters.
+        ASSERT_TRUE(response1);
+        ConstElementPtr sequence1 = response1->getJsonElement("sequence");
+        ASSERT_TRUE(sequence1);
+
+        ASSERT_TRUE(response2);
+        ConstElementPtr sequence2 = response2->getJsonElement("sequence");
+        ASSERT_TRUE(sequence2);
+
+        EXPECT_NE(sequence1->intValue(), sequence2->intValue());
+    }
+
+    /// @brief Test that the client can communicate with two different
+    /// destinations simultaneously.
+    void testMultipleDestinations() {
+        // Start two servers running on different ports.
+        ASSERT_NO_THROW(listener_.start());
+        ASSERT_NO_THROW(listener2_.start());
+
+        // Create the client. It will be communicating with the two servers.
+        HttpClient client(io_service_);
+
+        // Specify the URLs on which the servers are available.
+        Url url1("http://127.0.0.1:18123");
+        Url url2("http://[::1]:18124");
+
+        // Create a request to the first server.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        unsigned resp_num = 0;
+        ASSERT_NO_THROW(client.asyncSendRequest(url1, context1,
+                                                request1, response1,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+            EXPECT_FALSE(ec);
+        }));
+
+        // Create a request to the second server.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url2, context2,
+                                                request2, response2,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+            EXPECT_FALSE(ec);
+        }));
+
+        // Actually trigger the requests.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sure we have received two different responses.
+        ASSERT_TRUE(response1);
+        ConstElementPtr sequence1 = response1->getJsonElement("sequence");
+        ASSERT_TRUE(sequence1);
+
+        ASSERT_TRUE(response2);
+        ConstElementPtr sequence2 = response2->getJsonElement("sequence");
+        ASSERT_TRUE(sequence2);
+
+        EXPECT_NE(sequence1->intValue(), sequence2->intValue());
+    }
+
+    /// @brief Test that idle connection can be resumed for second request.
+    void testIdleConnection() {
+        // Start the server that has short idle timeout. It closes the idle
+        // connection after 200ms.
+        ASSERT_NO_THROW(listener3_.start());
+
+        // Create the client that will communicate with this server.
+        HttpClient client(io_service_);
+
+        // Specify the URL of this server.
+        Url url("http://127.0.0.1:18125");
+
+        // Create the first request.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [this](const boost::system::error_code& ec, const HttpResponsePtr&,
+                   const std::string&) {
+            io_service_.stop();
+            EXPECT_FALSE(ec);
+        }));
+
+        // Run the IO service until the response is received.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sure the response has been received.
+        ASSERT_TRUE(response1);
+        ConstElementPtr sequence1 = response1->getJsonElement("sequence");
+        ASSERT_TRUE(sequence1);
+
+        // Delay the generation of the second request by 2x server idle timeout.
+        // This should be enough to cause the server to close the connection.
+        ASSERT_NO_THROW(runIOService(SHORT_IDLE_TIMEOUT * 2));
+
+        // Create another request.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                request2, response2,
+            [this](const boost::system::error_code& ec, const HttpResponsePtr&,
+                   const std::string&) {
+            io_service_.stop();
+            EXPECT_FALSE(ec);
+        }));
+
+        // Actually trigger the second request.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sire that the server has responded.
+        ASSERT_TRUE(response2);
+        ConstElementPtr sequence2 = response2->getJsonElement("sequence");
+        ASSERT_TRUE(sequence2);
+
+        // Make sure that two different responses have been received.
+        EXPECT_NE(sequence1->intValue(), sequence2->intValue());
+    }
+
+    /// @brief This test verifies that the client returns IO error code when the
+    /// server is unreachable.
+    void testUnreachable () {
+        // Create the client.
+        HttpClient client(io_service_);
+
+        // Specify the URL of the server. This server is down.
+        Url url("http://127.0.0.1:18123");
+
+        // Create the request.
+        TlsContextPtr context;
+        PostHttpRequestJsonPtr request = createRequest("sequence", 1);
+        HttpResponseJsonPtr response(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+                                                request, response,
+            [this](const boost::system::error_code& ec,
+                   const HttpResponsePtr&,
+                   const std::string&) {
+            io_service_.stop();
+            // The server should have returned an IO error.
+            EXPECT_TRUE(ec);
+        }));
+
+        // Actually trigger the request.
+        ASSERT_NO_THROW(runIOService());
+    }
+
+    /// @brief Test that an error is returned by the client if the server
+    /// response is malformed.
+    void testMalformedResponse () {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create the client.
+        HttpClient client(io_service_);
+
+        // Specify the URL of the server.
+        Url url("http://127.0.0.1:18123");
+
+        TlsContextPtr context;
+        // The response is going to be malformed in such a way that it holds
+        // an invalid content type. We affect the content type by creating
+        // a request that holds a JSON parameter requesting a specific
+        // content type.
+        PostHttpRequestJsonPtr request = createRequest("requested-content-type",
+                                                       "text/html");
+        HttpResponseJsonPtr response(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+                                                request, response,
+            [this](const boost::system::error_code& ec,
+                   const HttpResponsePtr& response,
+                   const std::string& parsing_error) {
+            io_service_.stop();
+            // There should be no IO error (answer from the server is received).
+            EXPECT_FALSE(ec);
+            // The response object is NULL because it couldn't be finalized.
+            EXPECT_FALSE(response);
+            // The message parsing error should be returned.
+            EXPECT_FALSE(parsing_error.empty());
+        }));
+
+        // Actually trigger the request.
+        ASSERT_NO_THROW(runIOService());
+    }
+
+    /// @brief Test that client times out when it doesn't receive the entire
+    /// response from the server within a desired time.
+    void testClientRequestTimeout() {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create the client.
+        HttpClient client(io_service_);
+
+        // Specify the URL of the server.
+        Url url("http://127.0.0.1:18123");
+
+        unsigned cb_num = 0;
+
+        TlsContextPtr context1;
+        // Create the request which asks the server to generate a partial
+        // (although well formed) response. The client will be waiting for the
+        // rest of the response to be provided and will eventually time out.
+        PostHttpRequestJsonPtr request1 = createRequest("partial-response", true);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        // This value will be set to true if the connection close callback is
+        // invoked upon time out.
+        auto connection_closed = false;
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [this, &cb_num](const boost::system::error_code& ec,
+                            const HttpResponsePtr& response,
+                            const std::string&) {
+                if (++cb_num > 1) {
+                    io_service_.stop();
+                }
+                // In this particular case we know exactly the type of the
+                // IO error returned, because the client explicitly sets this
+                // error code.
+                EXPECT_TRUE(ec.value() == boost::asio::error::timed_out);
+                // There should be no response returned.
+                EXPECT_FALSE(response);
+            },
+            HttpClient::RequestTimeout(100),
+            HttpClient::ConnectHandler(),
+            HttpClient::HandshakeHandler(),
+            [&connection_closed](const int) {
+                // This callback is called when the connection gets closed
+                // by the client.
+                connection_closed = true;
+            })
+        );
+
+        // Create another request after the timeout. It should be handled ok.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 1);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                request2, response2,
+            [this, &cb_num](const boost::system::error_code& /*ec*/,
+                            const HttpResponsePtr&,
+                            const std::string&) {
+                if (++cb_num > 1) {
+                    io_service_.stop();
+                }
+            }));
+
+        // Actually trigger the requests.
+        ASSERT_NO_THROW(runIOService());
+        // Make sure that the client has closed the connection upon timeout.
+        EXPECT_TRUE(connection_closed);
+    }
+
+    /// @brief Test that client times out when connection takes too long.
+    void testClientConnectTimeout() {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create the client.
+        HttpClient client(io_service_);
+
+        // Specify the URL of the server.
+        Url url("http://127.0.0.1:18123");
+
+        unsigned cb_num = 0;
+
+        TlsContextPtr context;
+        PostHttpRequestJsonPtr request = createRequest("sequence", 1);
+        HttpResponseJsonPtr response(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+                                                request, response,
+            [this, &cb_num](const boost::system::error_code& ec,
+                            const HttpResponsePtr& response,
+                            const std::string&) {
+            if (++cb_num > 1) {
+                io_service_.stop();
+            }
+            // In this particular case we know exactly the type of the
+            // IO error returned, because the client explicitly sets this
+            // error code.
+            EXPECT_TRUE(ec.value() == boost::asio::error::timed_out);
+            // There should be no response returned.
+            EXPECT_FALSE(response);
+
+        }, HttpClient::RequestTimeout(100),
+
+           // This callback is invoked upon an attempt to connect to the
+           // server. The false value indicates to the HttpClient to not
+           // try to send a request to the server. This simulates the
+           // case of connect() taking very long and should eventually
+           // cause the transaction to time out.
+           [](const boost::system::error_code& /*ec*/, int) {
+               return (false);
+        }));
+
+        // Create another request after the timeout. It should be handled ok.
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context,
+                                                request, response,
+            [this, &cb_num](const boost::system::error_code& /*ec*/,
+                            const HttpResponsePtr&,
+                            const std::string&) {
+                if (++cb_num > 1) {
+                    io_service_.stop();
+                }
+            }));
+
+        // Actually trigger the requests.
+        ASSERT_NO_THROW(runIOService());
+    }
+
+    /// @brief Tests the behavior of the HTTP client when the premature
+    /// timeout occurs.
+    ///
+    /// The premature timeout may occur when the system clock is moved
+    /// during the transaction. This test simulates this behavior by
+    /// starting new transaction and waiting for the timeout to occur
+    /// before the IO service is ran. The timeout handler is invoked
+    /// first and it resets the transaction state. This test verifies
+    /// that the started transaction tears down gracefully after the
+    /// transaction state is reset.
+    ///
+    /// There are two variants of this test. The first variant schedules
+    /// one transaction before running the IO service. The second variant
+    /// schedules two transactions prior to running the IO service. The
+    /// second transaction is queued, so it is expected that it doesn't
+    /// time out and it runs successfully.
+    ///
+    /// @param queue_two_requests Boolean value indicating if a single
+    /// transaction should be queued (false), or two (true).
+    void testClientRequestLateStart(const bool queue_two_requests) {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create the client.
+        HttpClient client(io_service_);
+
+        // Specify the URL of the server.
+        Url url("http://127.0.0.1:18123");
+
+        // Generate first request.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+
+        // Use very short timeout to make sure that it occurs before we actually
+        // run the transaction.
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [](const boost::system::error_code& ec,
+               const HttpResponsePtr& response,
+               const std::string&) {
+
+            // In this particular case we know exactly the type of the
+            // IO error returned, because the client explicitly sets this
+            // error code.
+            EXPECT_TRUE(ec.value() == boost::asio::error::timed_out);
+            // There should be no response returned.
+            EXPECT_FALSE(response);
+        }, HttpClient::RequestTimeout(1)));
+
+        if (queue_two_requests) {
+            TlsContextPtr context2;
+            PostHttpRequestJsonPtr request2 = createRequest("sequence", 2);
+            HttpResponseJsonPtr response2(new HttpResponseJson());
+            ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                    request2, response2,
+                [](const boost::system::error_code& ec,
+                   const HttpResponsePtr& response,
+                   const std::string&) {
+
+                // This second request should be successful.
+                EXPECT_TRUE(ec.value() == 0);
+                EXPECT_TRUE(response);
+            }));
+        }
+
+        // This waits for 3ms to make sure that the timeout occurs before we
+        // run the transaction. This leads to an unusual situation that the
+        // transaction state is reset as a result of the timeout but the
+        // transaction is alive. We want to make sure that the client can
+        // gracefully deal with this situation.
+        usleep(3000);
+
+        // Run the transaction and hope it will gracefully tear down.
+        ASSERT_NO_THROW(runIOService(100));
+
+        // Now try to send another request to make sure that the client
+        // is healthy.
+        TlsContextPtr context3;
+        PostHttpRequestJsonPtr request3 = createRequest("sequence", 3);
+        HttpResponseJsonPtr response3(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context3,
+                                                request3, response3,
+                         [this](const boost::system::error_code& ec,
+                                const HttpResponsePtr&,
+                                const std::string&) {
+            io_service_.stop();
+
+            // Everything should be ok.
+            EXPECT_TRUE(ec.value() == 0);
+        }));
+
+        // Actually trigger the requests.
+        ASSERT_NO_THROW(runIOService());
+    }
+
+    /// @brief Tests that underlying TCP socket can be registered and
+    /// unregistered via connection and close callbacks.
+    ///
+    /// It conducts to consecutive requests over the same client.
+    ///
+    /// @param version HTTP version to be used.
+    void testConnectCloseCallbacks(const HttpVersion& version) {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create a client and specify the URL on which the server can be reached.
+        HttpClient client(io_service_);
+        Url url("http://127.0.0.1:18123");
+
+        // Initiate request to the server.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        unsigned resp_num = 0;
+        ExternalMonitor monitor;
+
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+
+            EXPECT_FALSE(ec);
+        },
+            HttpClient::RequestTimeout(10000),
+            std::bind(&ExternalMonitor::connectHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::handshakeHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::closeHandler, &monitor, ph::_1)
+        ));
+
+        // Initiate another request to the destination.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                request2, response2,
+            [this, &resp_num](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num > 1) {
+                io_service_.stop();
+            }
+            EXPECT_FALSE(ec);
+        },
+            HttpClient::RequestTimeout(10000),
+            std::bind(&ExternalMonitor::connectHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::handshakeHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::closeHandler, &monitor, ph::_1)
+        ));
+
+        // Actually trigger the requests. The requests should be handlded by the
+        // server one after another. While the first request is being processed
+        // the server should queue another one.
+        ASSERT_NO_THROW(runIOService());
+
+        // We should have had 2 connect invocations, no closes
+        // and a valid registered fd
+        EXPECT_EQ(2, monitor.connect_cnt_);
+        EXPECT_EQ(0, monitor.close_cnt_);
+        EXPECT_GT(monitor.registered_fd_, -1);
+
+        // Make sure that the received responses are different. We check that by
+        // comparing value of the sequence parameters.
+        ASSERT_TRUE(response1);
+        ConstElementPtr sequence1 = response1->getJsonElement("sequence");
+        ASSERT_TRUE(sequence1);
+
+        ASSERT_TRUE(response2);
+        ConstElementPtr sequence2 = response2->getJsonElement("sequence");
+        ASSERT_TRUE(sequence2);
+        EXPECT_NE(sequence1->intValue(), sequence2->intValue());
+
+        // Stopping the client the close the connection.
+        client.stop();
+
+        // We should have had 2 connect invocations, 1 closes
+        // and an invalid registered fd
+        EXPECT_EQ(2, monitor.connect_cnt_);
+        EXPECT_EQ(1, monitor.close_cnt_);
+        EXPECT_EQ(-1, monitor.registered_fd_);
+    }
+
+    /// @brief Tests detection and handling out-of-band socket events
+    ///
+    /// It initiates a transaction and verifies that a mid-transaction call
+    /// to HttpClient::closeIfOutOfBand() has no affect on the connection.
+    /// After successful completion of the transaction, a second call to
+    /// HttpClient::closeIfOutOfBand() is made. This should result in the
+    /// connection being closed.
+    /// This step is repeated to verify that after an OOB closure, transactions
+    /// to the same destination can be processed.
+    ///
+    /// Lastly, we verify that HttpClient::stop() closes the connection correctly.
+    ///
+    /// @param version HTTP version to be used.
+    void testCloseIfOutOfBand(const HttpVersion& version) {
+        // Start the server.
+        ASSERT_NO_THROW(listener_.start());
+
+        // Create a client and specify the URL on which the server can be reached.
+        HttpClient client(io_service_);
+        Url url("http://127.0.0.1:18123");
+
+        // Initiate request to the server.
+        TlsContextPtr context1;
+        PostHttpRequestJsonPtr request1 = createRequest("sequence", 1, version);
+        HttpResponseJsonPtr response1(new HttpResponseJson());
+        unsigned resp_num = 0;
+        ExternalMonitor monitor;
+
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context1,
+                                                request1, response1,
+            [this, &client, &resp_num, &monitor](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num == 1) {
+                io_service_.stop();
+            }
+
+            EXPECT_EQ(1, monitor.connect_cnt_);      // We should have 1 connect.
+            EXPECT_EQ(0, monitor.close_cnt_);        // We should have 0 closes
+            ASSERT_GT(monitor.registered_fd_, -1);   // We should have a valid fd.
+            int orig_fd = monitor.registered_fd_;
+
+            // Test our socket for OOBness.
+            client.closeIfOutOfBand(monitor.registered_fd_);
+
+            // Since we're in a transaction, we should have no closes and
+            // the same valid fd.
+            EXPECT_EQ(0, monitor.close_cnt_);
+            ASSERT_EQ(monitor.registered_fd_, orig_fd);
+
+            EXPECT_FALSE(ec);
+        },
+            HttpClient::RequestTimeout(10000),
+            std::bind(&ExternalMonitor::connectHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::handshakeHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::closeHandler, &monitor, ph::_1)
+        ));
+
+        // Actually trigger the requests. The requests should be handlded by the
+        // server one after another. While the first request is being processed
+        // the server should queue another one.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sure that we received a response.
+        ASSERT_TRUE(response1);
+        ConstElementPtr sequence1 = response1->getJsonElement("sequence");
+        ASSERT_TRUE(sequence1);
+        EXPECT_EQ(1, sequence1->intValue());
+
+        // We should have had 1 connect invocations, no closes
+        // and a valid registered fd
+        EXPECT_EQ(1, monitor.connect_cnt_);
+        EXPECT_EQ(0, monitor.close_cnt_);
+        EXPECT_GT(monitor.registered_fd_, -1);
+
+        // Test our socket for OOBness.
+        client.closeIfOutOfBand(monitor.registered_fd_);
+
+        // Since we're in a transaction, we should have no closes and
+        // the same valid fd.
+        EXPECT_EQ(1, monitor.close_cnt_);
+        EXPECT_EQ(-1, monitor.registered_fd_);
+
+        // Now let's do another request to the destination to verify that
+        // we'll reopen the connection without issue.
+        TlsContextPtr context2;
+        PostHttpRequestJsonPtr request2 = createRequest("sequence", 2, version);
+        HttpResponseJsonPtr response2(new HttpResponseJson());
+        resp_num = 0;
+        ASSERT_NO_THROW(client.asyncSendRequest(url, context2,
+                                                request2, response2,
+            [this, &client, &resp_num, &monitor](const boost::system::error_code& ec,
+                              const HttpResponsePtr&,
+                              const std::string&) {
+            if (++resp_num == 1) {
+                io_service_.stop();
+            }
+
+            EXPECT_EQ(2, monitor.connect_cnt_);      // We should have 1 connect.
+            EXPECT_EQ(1, monitor.close_cnt_);        // We should have 0 closes
+            ASSERT_GT(monitor.registered_fd_, -1);   // We should have a valid fd.
+            int orig_fd = monitor.registered_fd_;
+
+            // Test our socket for OOBness.
+            client.closeIfOutOfBand(monitor.registered_fd_);
+
+            // Since we're in a transaction, we should have no closes and
+            // the same valid fd.
+            EXPECT_EQ(1, monitor.close_cnt_);
+            ASSERT_EQ(monitor.registered_fd_, orig_fd);
+
+            EXPECT_FALSE(ec);
+        },
+            HttpClient::RequestTimeout(10000),
+            std::bind(&ExternalMonitor::connectHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::handshakeHandler, &monitor, ph::_1, ph::_2),
+            std::bind(&ExternalMonitor::closeHandler, &monitor, ph::_1)
+        ));
+
+        // Actually trigger the requests. The requests should be handlded by the
+        // server one after another. While the first request is being processed
+        // the server should queue another one.
+        ASSERT_NO_THROW(runIOService());
+
+        // Make sure that we received the second response.
+        ASSERT_TRUE(response2);
+        ConstElementPtr sequence2 = response2->getJsonElement("sequence");
+        ASSERT_TRUE(sequence2);
+        EXPECT_EQ(2, sequence2->intValue());
+
+        // Stopping the client the close the connection.
+        client.stop();
+
+        // We should have had 2 connect invocations, 2 closes
+        // and an invalid registered fd
+        EXPECT_EQ(2, monitor.connect_cnt_);
+        EXPECT_EQ(2, monitor.close_cnt_);
+        EXPECT_EQ(-1, monitor.registered_fd_);
+    }
+
+    /// @brief Simulates external registery of Connection TCP sockets
+    ///
+    /// Provides methods compatible with Connection callbacks for connnect
+    /// and close operations.
+    class ExternalMonitor {
+    public:
+        /// @brief Constructor
+        ExternalMonitor()
+            : registered_fd_(-1), connect_cnt_(0), handshake_cnt_(0),
+              close_cnt_(0) {
+        }
+
+        /// @brief Connect callback handler
+        /// @param ec Error status of the ASIO connect
+        /// @param tcp_native_fd socket descriptor to register
+        bool connectHandler(const boost::system::error_code& ec, int tcp_native_fd) {
+            ++connect_cnt_;
+            if ((!ec || (ec.value() == boost::asio::error::in_progress))
+                && (tcp_native_fd >= 0)) {
+                registered_fd_ = tcp_native_fd;
+                return (true);
+            } else if ((ec.value() == boost::asio::error::already_connected)
+                       && (registered_fd_ != tcp_native_fd)) {
+                return (false);
+            }
+
+            // ec indicates an error, return true, so that error can be handled
+            // by Connection logic.
+            return (true);
+        }
+
+        /// @brief Handshake callback handler
+        /// @param ec Error status of the ASIO connect
+        bool handshakeHandler(const boost::system::error_code& ec, int) {
+            ++handshake_cnt_;
+            // ec indicates an error, return true, so that error can be handled
+            // by Connection logic.
+            return (true);
+        }
+
+        /// @brief Close callback handler
+        ///
+        /// @param tcp_native_fd socket descriptor to register
+        void closeHandler(int tcp_native_fd) {
+            ++close_cnt_;
+            EXPECT_EQ(tcp_native_fd, registered_fd_) << "closeHandler fd mismatch";
+            if (tcp_native_fd >= 0) {
+                registered_fd_ = -1;
+            }
+        }
+
+        /// @brief Keeps track of socket currently "registered" for external monitoring.
+        int registered_fd_;
+
+        /// @brief Tracks how many times the connect callback is invoked.
+        int connect_cnt_;
+
+        /// @brief Tracks how many times the handshake callback is invoked.
+        int handshake_cnt_;
+
+        /// @brief Tracks how many times the close callback is invoked.
+        int close_cnt_;
+    };
+
+    /// @brief Instance of the listener used in the tests.
+    HttpListener listener_;
+
+    /// @brief Instance of the second listener used in the tests.
+    HttpListener listener2_;
+
+    /// @brief Instance of the third listener used in the tests (with short idle
+    /// timeout).
+    HttpListener listener3_;
+
+};
+
+// Test that two consecutive requests can be sent over the same (persistent)
+// connection.
+TEST_F(HttpsClientTest, consecutiveRequests) {
+    ASSERT_NO_FATAL_FAILURE(testConsecutiveRequests(HttpVersion(1, 1)));
+}
+
+// Test that two consecutive requests can be sent over the same (persistent)
+// connection.
+TEST_F(HttpsClientTest, consecutiveRequestsMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testConsecutiveRequests(HttpVersion(1, 1)));
+}
+
+// Test that two consecutive requests can be sent over non-persistent connection.
+// This is achieved by sending HTTP/1.0 requests, which are non-persistent by
+// default. The client should close the connection right after receiving a response
+// from the server.
+TEST_F(HttpsClientTest, closeBetweenRequests) {
+    ASSERT_NO_FATAL_FAILURE(testConsecutiveRequests(HttpVersion(1, 0)));
+}
+
+// Test that two consecutive requests can be sent over non-persistent connection.
+// This is achieved by sending HTTP/1.0 requests, which are non-persistent by
+// default. The client should close the connection right after receiving a response
+// from the server.
+TEST_F(HttpsClientTest, closeBetweenRequestsMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testConsecutiveRequests(HttpVersion(1, 0)));
+}
+
+// Test that the client can communicate with two different destinations
+// simultaneously.
+TEST_F(HttpsClientTest, multipleDestinations) {
+    ASSERT_NO_FATAL_FAILURE(testMultipleDestinations());
+}
+
+// Test that the client can communicate with two different destinations
+// simultaneously.
+TEST_F(HttpsClientTest, multipleDestinationsMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testMultipleDestinations());
+}
+
+// Test that idle connection can be resumed for second request.
+TEST_F(HttpsClientTest, idleConnection) {
+    ASSERT_NO_FATAL_FAILURE(testIdleConnection());
+}
+
+// Test that idle connection can be resumed for second request.
+TEST_F(HttpsClientTest, idleConnectionMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testIdleConnection());
+}
+
+// This test verifies that the client returns IO error code when the
+// server is unreachable.
+TEST_F(HttpsClientTest, unreachable) {
+    ASSERT_NO_FATAL_FAILURE(testUnreachable());
+}
+
+// This test verifies that the client returns IO error code when the
+// server is unreachable.
+TEST_F(HttpsClientTest, unreachableMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testUnreachable());
+}
+
+// Test that an error is returned by the client if the server response is
+// malformed.
+TEST_F(HttpsClientTest, malformedResponse) {
+    ASSERT_NO_FATAL_FAILURE(testMalformedResponse());
+}
+
+// Test that an error is returned by the client if the server response is
+// malformed.
+TEST_F(HttpsClientTest, malformedResponseMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testMalformedResponse());
+}
+
+// Test that client times out when it doesn't receive the entire response
+// from the server within a desired time.
+TEST_F(HttpsClientTest, clientRequestTimeout) {
+    ASSERT_NO_FATAL_FAILURE(testClientRequestTimeout());
+}
+
+// Test that client times out when it doesn't receive the entire response
+// from the server within a desired time.
+TEST_F(HttpsClientTest, clientRequestTimeoutMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testClientRequestTimeout());
+}
+
+// This test verifies the behavior of the HTTP client when the premature
+// (and unexpected) timeout occurs. The premature timeout may be caused
+// by the system clock move.
+TEST_F(HttpsClientTest, clientRequestLateStartNoQueue) {
+    testClientRequestLateStart(false);
+}
+
+// This test verifies the behavior of the HTTP client when the premature
+// (and unexpected) timeout occurs. The premature timeout may be caused
+// by the system clock move.
+TEST_F(HttpsClientTest, clientRequestLateStartNoQueueMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    testClientRequestLateStart(false);
+}
+
+// This test verifies the behavior of the HTTP client when the premature
+// timeout occurs and there are requests queued after the request which
+// times out.
+TEST_F(HttpsClientTest, clientRequestLateStartQueue) {
+    testClientRequestLateStart(true);
+}
+
+// This test verifies the behavior of the HTTP client when the premature
+// timeout occurs and there are requests queued after the request which
+// times out.
+TEST_F(HttpsClientTest, clientRequestLateStartQueueMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    testClientRequestLateStart(true);
+}
+
+// Test that client times out when connection takes too long.
+TEST_F(HttpsClientTest, clientConnectTimeout) {
+    ASSERT_NO_FATAL_FAILURE(testClientConnectTimeout());
+}
+
+// Test that client times out when connection takes too long.
+TEST_F(HttpsClientTest, clientConnectTimeoutMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testClientConnectTimeout());
+}
+
+/// Tests that connect and close callbacks work correctly.
+TEST_F(HttpsClientTest, connectCloseCallbacks) {
+    ASSERT_NO_FATAL_FAILURE(testConnectCloseCallbacks(HttpVersion(1, 1)));
+}
+
+/// Tests that connect and close callbacks work correctly.
+TEST_F(HttpsClientTest, connectCloseCallbacksMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testConnectCloseCallbacks(HttpVersion(1, 1)));
+}
+
+/// Tests that HttpClient::closeIfOutOfBand works correctly.
+TEST_F(HttpsClientTest, closeIfOutOfBand) {
+    ASSERT_NO_FATAL_FAILURE(testCloseIfOutOfBand(HttpVersion(1, 1)));
+}
+
+/// Tests that HttpClient::closeIfOutOfBand works correctly.
+TEST_F(HttpsClientTest, closeIfOutOfBandMultiThreading) {
+    MultiThreadingMgr::instance().setMode(true);
+    ASSERT_NO_FATAL_FAILURE(testCloseIfOutOfBand(HttpVersion(1, 1)));
+}
+
+}
diff --git a/src/lib/http/tests/tls_server_unittests.cc b/src/lib/http/tests/tls_server_unittests.cc
new file mode 100644
index 0000000000..fc500804e0
--- /dev/null
+++ b/src/lib/http/tests/tls_server_unittests.cc
@@ -0,0 +1,1254 @@
+// Copyright (C) 2017-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include <config.h>
+#include <asiolink/asio_wrapper.h>
+#include <asiolink/interval_timer.h>
+#include <asiolink/tls_acceptor.h>
+#include <cc/data.h>
+#include <http/client.h>
+#include <http/http_types.h>
+#include <http/listener.h>
+#include <http/listener_impl.h>
+#include <http/post_request_json.h>
+#include <http/response_creator.h>
+#include <http/response_creator_factory.h>
+#include <http/response_json.h>
+#include <http/tests/response_test.h>
+#include <http/url.h>
+#include <util/multi_threading_mgr.h>
+
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <boost/pointer_cast.hpp>
+#include <gtest/gtest.h>
+
+#include <functional>
+#include <list>
+#include <sstream>
+#include <string>
+
+using namespace boost::asio::ip;
+using namespace isc::asiolink;
+using namespace isc::data;
+using namespace isc::http;
+using namespace isc::http::test;
+using namespace isc::util;
+namespace ph = std::placeholders;
+
+namespace {
+
+/// @brief IP address to which HTTP service is bound.
+const std::string SERVER_ADDRESS = "127.0.0.1";
+
+/// @brief IPv6 address to whch HTTP service is bound.
+const std::string IPV6_SERVER_ADDRESS = "::1";
+
+/// @brief Port number to which HTTP service is bound.
+const unsigned short SERVER_PORT = 18123;
+
+/// @brief Request Timeout used in most of the tests (ms).
+const long REQUEST_TIMEOUT = 10000;
+
+/// @brief Persistent connection idle timeout used in most of the tests (ms).
+const long IDLE_TIMEOUT = 10000;
+
+/// @brief Persistent connection idle timeout used in tests where idle connections
+/// are tested (ms).
+const long SHORT_IDLE_TIMEOUT = 200;
+
+/// @brief Test timeout (ms).
+const long TEST_TIMEOUT = 10000;
+
+/// @brief Test HTTP response.
+typedef TestHttpResponseBase<HttpResponseJson> Response;
+
+/// @brief Pointer to test HTTP response.
+typedef boost::shared_ptr<Response> ResponsePtr;
+
+/// @brief Generic test HTTP response.
+typedef TestHttpResponseBase<HttpResponse> GenericResponse;
+
+/// @brief Pointer to generic test HTTP response.
+typedef boost::shared_ptr<GenericResponse> GenericResponsePtr;
+
+/// @brief Implementation of the @ref HttpResponseCreator.
+class TestHttpResponseCreator : public HttpResponseCreator {
+public:
+
+    /// @brief Create a new request.
+    ///
+    /// @return Pointer to the new instance of the @ref HttpRequest.
+    virtual HttpRequestPtr
+    createNewHttpRequest() const {
+        return (HttpRequestPtr(new PostHttpRequestJson()));
+    }
+
+private:
+
+    /// @brief Creates HTTP response.
+    ///
+    /// @param request Pointer to the HTTP request.
+    /// @return Pointer to the generated HTTP response.
+    virtual HttpResponsePtr
+    createStockHttpResponse(const HttpRequestPtr& request,
+                            const HttpStatusCode& status_code) const {
+        // The request hasn't been finalized so the request object
+        // doesn't contain any information about the HTTP version number
+        // used. But, the context should have this data (assuming the
+        // HTTP version is parsed ok).
+        HttpVersion http_version(request->context()->http_version_major_,
+                                 request->context()->http_version_minor_);
+        // This will generate the response holding JSON content.
+        ResponsePtr response(new Response(http_version, status_code));
+        response->finalize();
+        return (response);
+    }
+
+    /// @brief Creates HTTP response.
+    ///
+    /// This method generates 3 types of responses:
+    /// - response with a requested content type,
+    /// - partial response with incomplete JSON body,
+    /// - response with JSON body copied from the request.
+    ///
+    /// The first one is useful to test situations when received response can't
+    /// be parsed because of the content type mismatch. The second one is useful
+    /// to test request timeouts. The third type is used by most of the unit tests
+    /// to test successful transactions.
+    ///
+    /// @param request Pointer to the HTTP request.
+    /// @return Pointer to the generated HTTP OK response with no content.
+    virtual HttpResponsePtr
+    createDynamicHttpResponse(HttpRequestPtr request) {
+        // Request must always be JSON.
+        PostHttpRequestJsonPtr request_json =
+            boost::dynamic_pointer_cast<PostHttpRequestJson>(request);
+        ConstElementPtr body;
+        if (request_json) {
+            body = request_json->getBodyAsJson();
+            if (body) {
+                // Check if the client requested one of the two first response
+                // types.
+                GenericResponsePtr response;
+                ConstElementPtr content_type = body->get("requested-content-type");
+                ConstElementPtr partial_response = body->get("partial-response");
+                if (content_type || partial_response) {
+                    // The first two response types can only be generated using the
+                    // generic response as we have to explicitly modify some of the
+                    // values.
+                    response.reset(new GenericResponse(request->getHttpVersion(),
+                                                       HttpStatusCode::OK));
+                    HttpResponseContextPtr ctx = response->context();
+
+                    if (content_type) {
+                        // Provide requested content type.
+                        ctx->headers_.push_back(HttpHeaderContext("Content-Type",
+                                                                  content_type->stringValue()));
+                        // It doesn't matter what body is there.
+                        ctx->body_ = "abcd";
+                        response->finalize();
+
+                    } else {
+                        // Generate JSON response.
+                        ctx->headers_.push_back(HttpHeaderContext("Content-Type",
+                                                                  "application/json"));
+                        // The body lacks '}' so the client will be waiting for it and
+                        // eventually should time out.
+                        ctx->body_ = "{";
+                        response->finalize();
+                        // The auto generated Content-Length header would be based on the
+                        // body size (so set to 1 byte). We have to override it to
+                        // account for the missing '}' character.
+                        response->setContentLength(2);
+                    }
+                    return (response);
+                }
+            }
+        }
+
+        // Third type of response is requested.
+        ResponsePtr response(new Response(request->getHttpVersion(),
+                                          HttpStatusCode::OK));
+        // If body was included in the request. Let's copy it.
+        if (body) {
+            response->setBodyAsJson(body);
+        }
+
+        response->finalize();
+        return (response);
+    }
+};
+
+/// @brief Implementation of the test @ref HttpResponseCreatorFactory.
+///
+/// This factory class creates @ref TestHttpResponseCreator instances.
+class TestHttpResponseCreatorFactory : public HttpResponseCreatorFactory {
+public:
+
+    /// @brief Creates @ref TestHttpResponseCreator instance.
+    virtual HttpResponseCreatorPtr create() const {
+        HttpResponseCreatorPtr response_creator(new TestHttpResponseCreator());
+        return (response_creator);
+    }
+};
+
+/// @brief Implementation of the HTTP listener used in tests.
+///
+/// This implementation replaces the @c HttpConnection type with a custom
+/// implementation.
+///
+/// @tparam HttpConnectionType Type of the connection object to be used by
+/// the listener implementation.
+template<typename HttpConnectionType>
+class HttpListenerImplCustom : public HttpListenerImpl {
+public:
+
+    HttpListenerImplCustom(IOService& io_service,
+                           const IOAddress& server_address,
+                           const unsigned short server_port,
+                           const TlsContextPtr& context,
+                           const HttpResponseCreatorFactoryPtr& creator_factory,
+                           const long request_timeout,
+                           const long idle_timeout)
+        : HttpListenerImpl(io_service, server_address, server_port,
+                           context, creator_factory, request_timeout,
+                           idle_timeout) {
+    }
+
+protected:
+
+    /// @brief Creates an instance of the @c HttpConnection.
+    ///
+    /// This method is virtual so as it can be overridden when customized
+    /// connections are to be used, e.g. in case of unit testing.
+    ///
+    /// @param io_service IO service to be used by the connection.
+    /// @param acceptor Pointer to the TCP acceptor object used to listen for
+    /// new HTTP connections.
+    /// @param context TLS context.
+    /// @param connection_pool Connection pool in which this connection is
+    /// stored.
+    /// @param response_creator Pointer to the response creator object used to
+    /// create HTTP response from the HTTP request received.
+    /// @param acceptor_callback Callback invoked when new connection is accepted.
+    /// @param handshake_callback Callback invoked when TLS handshake is performed.
+    /// @param request_timeout Configured timeout for a HTTP request.
+    /// @param idle_timeout Timeout after which persistent HTTP connection is
+    /// closed by the server.
+    ///
+    /// @return Pointer to the created connection.
+    virtual HttpConnectionPtr createConnection(const HttpResponseCreatorPtr& response_creator,
+                                               const HttpAcceptorCallback& acceptor_callback,
+                                               const HttpAcceptorCallback& handshake_callback) {
+        HttpConnectionPtr
+            conn(new HttpConnectionType(io_service_, acceptor_,
+                                        context_, connections_,
+                                        response_creator,
+                                        acceptor_callback, handshake_callback,
+                                        request_timeout_, idle_timeout_));
+        return (conn);
+    }
+};
+
+/// @brief Derivation of the @c HttpListener used in tests.
+///
+/// This class replaces the default implementation instance with the
+/// @c HttpListenerImplCustom using the customized connection type.
+///
+/// @tparam HttpConnectionType Type of the connection object to be used by
+/// the listener implementation.
+template<typename HttpConnectionType>
+class HttpListenerCustom : public HttpListener {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// @param io_service IO service to be used by the listener.
+    /// @param server_address Address on which the HTTP service should run.
+    /// @param server_port Port number on which the HTTP service should run.
+    /// @param context TLS context.
+    /// @param creator_factory Pointer to the caller-defined
+    /// @ref HttpResponseCreatorFactory derivation which should be used to
+    /// create @ref HttpResponseCreator instances.
+    /// @param request_timeout Timeout after which the HTTP Request Timeout
+    /// is generated.
+    /// @param idle_timeout Timeout after which an idle persistent HTTP
+    /// connection is closed by the server.
+    ///
+    /// @throw HttpListenerError when any of the specified parameters is
+    /// invalid.
+    HttpListenerCustom(IOService& io_service,
+                       const IOAddress& server_address,
+                       const unsigned short server_port,
+                       const TlsContextPtr& context,
+                       const HttpResponseCreatorFactoryPtr& creator_factory,
+                       const HttpListener::RequestTimeout& request_timeout,
+                       const HttpListener::IdleTimeout& idle_timeout)
+        : HttpListener(io_service, server_address, server_port,
+                       context, creator_factory,
+                       request_timeout, idle_timeout) {
+        // Replace the default implementation with the customized version
+        // using the custom derivation of the HttpConnection.
+        impl_.reset(new HttpListenerImplCustom<HttpConnectionType>
+                    (io_service, server_address, server_port,
+                     context, creator_factory, request_timeout.value_,
+                     idle_timeout.value_));
+    }
+};
+
+/// @brief Implementation of the @c HttpConnection which injects greater
+/// length value than the buffer size into the write socket callback.
+class HttpConnectionLongWriteBuffer : public HttpConnection {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// @param io_service IO service to be used by the connection.
+    /// @param acceptor Pointer to the TCP acceptor object used to listen for
+    /// new HTTP connections.
+    /// @param context TLS context.
+    /// @param connection_pool Connection pool in which this connection is
+    /// stored.
+    /// @param response_creator Pointer to the response creator object used to
+    /// create HTTP response from the HTTP request received.
+    /// @param acceptor_callback Callback invoked when new connection is accepted.
+    /// @param handshake_callback Callback invoked when TLS handshake is performed.
+    /// @param request_timeout Configured timeout for a HTTP request.
+    /// @param idle_timeout Timeout after which persistent HTTP connection is
+    /// closed by the server.
+    HttpConnectionLongWriteBuffer(IOService& io_service,
+                                  const HttpAcceptorPtr& acceptor,
+                                  const TlsContextPtr& context,
+                                  HttpConnectionPool& connection_pool,
+                                  const HttpResponseCreatorPtr& response_creator,
+                                  const HttpAcceptorCallback& acceptor_callback,
+                                  const HttpAcceptorCallback& handshake_callback,
+                                  const long request_timeout,
+                                  const long idle_timeout)
+        : HttpConnection(io_service, acceptor, context, connection_pool,
+                         response_creator, acceptor_callback,
+                         handshake_callback, request_timeout,
+                         idle_timeout) {
+    }
+
+    /// @brief Callback invoked when data is sent over the socket.
+    ///
+    /// @param transaction Pointer to the transaction for which the callback
+    /// is invoked.
+    /// @param ec Error code.
+    /// @param length Length of the data sent.
+    virtual void socketWriteCallback(HttpConnection::TransactionPtr transaction,
+                                     boost::system::error_code ec,
+                                     size_t length) {
+        // Pass greater length of the data written. The callback should deal
+        // with this and adjust the data length.
+        HttpConnection::socketWriteCallback(transaction, ec, length + 1);
+    }
+};
+
+/// @brief Implementation of the @c HttpConnection which replaces
+/// transaction instance prior to calling write socket callback.
+class HttpConnectionTransactionChange : public HttpConnection {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// @param io_service IO service to be used by the connection.
+    /// @param acceptor Pointer to the TCP acceptor object used to listen for
+    /// new HTTP connections.
+    /// @param context TLS context.
+    /// @param connection_pool Connection pool in which this connection is
+    /// stored.
+    /// @param response_creator Pointer to the response creator object used to
+    /// create HTTP response from the HTTP request received.
+    /// @param acceptor_callback Callback invoked when new connection is accepted.
+    /// @param handshake_callback Callback invoked when TLS handshake is performed.
+    /// @param request_timeout Configured timeout for a HTTP request.
+    /// @param idle_timeout Timeout after which persistent HTTP connection is
+    /// closed by the server.
+    HttpConnectionTransactionChange(IOService& io_service,
+                                    const HttpAcceptorPtr& acceptor,
+                                    const TlsContextPtr& context,
+                                    HttpConnectionPool& connection_pool,
+                                    const HttpResponseCreatorPtr& response_creator,
+                                    const HttpAcceptorCallback& acceptor_callback,
+                                    const HttpAcceptorCallback& handshake_callback,
+                                    const long request_timeout,
+                                    const long idle_timeout)
+        : HttpConnection(io_service, acceptor, context, connection_pool,
+                         response_creator, acceptor_callback,
+                         handshake_callback, request_timeout,
+                         idle_timeout) {
+    }
+
+    /// @brief Callback invoked when data is sent over the socket.
+    ///
+    /// @param transaction Pointer to the transaction for which the callback
+    /// is invoked.
+    /// @param ec Error code.
+    /// @param length Length of the data sent.
+    virtual void socketWriteCallback(HttpConnection::TransactionPtr transaction,
+                                     boost::system::error_code ec,
+                                     size_t length) {
+        // Replace the transaction. The socket callback should deal with this
+        // gracefully. It should detect that the output buffer is empty. Then
+        // try to see if the connection is persistent. This check should fail,
+        // because the request hasn't been created/finalized. The exception
+        // thrown upon checking the persistence should be caught and the
+        // connection closed.
+        transaction = HttpConnection::Transaction::create(response_creator_);
+        HttpConnection::socketWriteCallback(transaction, ec, length);
+    }
+};
+
+
+/// @brief Entity which can connect to the HTTP server endpoint.
+class TestHttpClient : public boost::noncopyable {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// This constructor creates new socket instance. It doesn't connect. Call
+    /// connect() to connect to the server.
+    ///
+    /// @param io_service IO service to be stopped on error.
+    explicit TestHttpClient(IOService& io_service)
+        : io_service_(io_service.get_io_service()), socket_(io_service_),
+          buf_(), response_() {
+    }
+
+    /// @brief Destructor.
+    ///
+    /// Closes the underlying socket if it is open.
+    ~TestHttpClient() {
+        close();
+    }
+
+    /// @brief Send HTTP request specified in textual format.
+    ///
+    /// @param request HTTP request in the textual format.
+    void startRequest(const std::string& request) {
+        tcp::endpoint endpoint(address::from_string(SERVER_ADDRESS),
+                               SERVER_PORT);
+        socket_.async_connect(endpoint,
+        [this, request](const boost::system::error_code& ec) {
+            if (ec) {
+                // One would expect that async_connect wouldn't return
+                // EINPROGRESS error code, but simply wait for the connection
+                // to get established before the handler is invoked. It turns out,
+                // however, that on some OSes the connect handler may receive this
+                // error code which doesn't necessarily indicate a problem.
+                // Making an attempt to write and read from this socket will
+                // typically succeed. So, we ignore this error.
+                if (ec.value() != boost::asio::error::in_progress) {
+                    ADD_FAILURE() << "error occurred while connecting: "
+                                  << ec.message();
+                    io_service_.stop();
+                    return;
+                }
+            }
+            sendRequest(request);
+        });
+    }
+
+    /// @brief Send HTTP request.
+    ///
+    /// @param request HTTP request in the textual format.
+    void sendRequest(const std::string& request) {
+        sendPartialRequest(request);
+    }
+
+    /// @brief Send part of the HTTP request.
+    ///
+    /// @param request part of the HTTP request to be sent.
+    void sendPartialRequest(std::string request) {
+        socket_.async_send(boost::asio::buffer(request.data(), request.size()),
+                           [this, request](const boost::system::error_code& ec,
+                                           std::size_t bytes_transferred) mutable {
+            if (ec) {
+                if (ec.value() == boost::asio::error::operation_aborted) {
+                    return;
+
+                } else if ((ec.value() == boost::asio::error::try_again) ||
+                           (ec.value() == boost::asio::error::would_block)) {
+                    // If we should try again make sure there is no garbage in the
+                    // bytes_transferred.
+                    bytes_transferred = 0;
+
+                } else {
+                    ADD_FAILURE() << "error occurred while connecting: "
+                                  << ec.message();
+                    io_service_.stop();
+                    return;
+                }
+            }
+
+            // Remove the part of the request which has been sent.
+            if (bytes_transferred > 0 && (request.size() <= bytes_transferred)) {
+                request.erase(0, bytes_transferred);
+            }
+
+            // Continue sending request data if there are still some data to be
+            // sent.
+            if (!request.empty()) {
+                sendPartialRequest(request);
+
+            } else {
+                // Request has been sent. Start receiving response.
+                response_.clear();
+                receivePartialResponse();
+            }
+       });
+    }
+
+    /// @brief Receive response from the server.
+    void receivePartialResponse() {
+        socket_.async_read_some(boost::asio::buffer(buf_.data(), buf_.size()),
+                                [this](const boost::system::error_code& ec,
+                                       std::size_t bytes_transferred) {
+            if (ec) {
+                // IO service stopped so simply return.
+                if (ec.value() == boost::asio::error::operation_aborted) {
+                    return;
+
+                } else if ((ec.value() == boost::asio::error::try_again) ||
+                           (ec.value() == boost::asio::error::would_block)) {
+                    // If we should try again, make sure that there is no garbage
+                    // in the bytes_transferred.
+                    bytes_transferred = 0;
+
+                } else {
+                    // Error occurred, bail...
+                    ADD_FAILURE() << "error occurred while receiving HTTP"
+                        " response from the server: " << ec.message();
+                    io_service_.stop();
+                }
+            }
+
+            if (bytes_transferred > 0) {
+                response_.insert(response_.end(), buf_.data(),
+                                 buf_.data() + bytes_transferred);
+            }
+
+            // Two consecutive new lines end the part of the response we're
+            // expecting.
+            if (response_.find("\r\n\r\n", 0) != std::string::npos) {
+                io_service_.stop();
+
+            } else {
+                receivePartialResponse();
+            }
+
+        });
+    }
+
+    /// @brief Checks if the TCP connection is still open.
+    ///
+    /// Tests the TCP connection by trying to read from the socket.
+    /// Unfortunately expected failure depends on a race between the read
+    /// and the other side close so to check if the connection is closed
+    /// please use @c isConnectionClosed instead.
+    ///
+    /// @return true if the TCP connection is open.
+    bool isConnectionAlive() {
+        // Remember the current non blocking setting.
+        const bool non_blocking_orig = socket_.non_blocking();
+        // Set the socket to non blocking mode. We're going to test if the socket
+        // returns would_block status on the attempt to read from it.
+        socket_.non_blocking(true);
+
+        // We need to provide a buffer for a call to read.
+        char data[2];
+        boost::system::error_code ec;
+        boost::asio::read(socket_, boost::asio::buffer(data, sizeof(data)), ec);
+
+        // Revert the original non_blocking flag on the socket.
+        socket_.non_blocking(non_blocking_orig);
+
+        // If the connection is alive we'd typically get would_block status code.
+        // If there are any data that haven't been read we may also get success
+        // status. We're guessing that try_again may also be returned by some
+        // implementations in some situations. Any other error code indicates a
+        // problem with the connection so we assume that the connection has been
+        // closed.
+        return (!ec || (ec.value() == boost::asio::error::try_again) ||
+                (ec.value() == boost::asio::error::would_block));
+    }
+
+    /// @brief Checks if the TCP connection is already closed.
+    ///
+    /// Tests the TCP connection by trying to read from the socket.
+    /// The read can block so this must be used to check if a connection
+    /// is alive so to check if the connection is alive please always
+    /// use @c isConnectionAlive.
+    ///
+    /// @return true if the TCP connection is closed.
+    bool isConnectionClosed() {
+        // Remember the current non blocking setting.
+        const bool non_blocking_orig = socket_.non_blocking();
+        // Set the socket to blocking mode. We're going to test if the socket
+        // returns eof status on the attempt to read from it.
+        socket_.non_blocking(false);
+
+        // We need to provide a buffer for a call to read.
+        char data[2];
+        boost::system::error_code ec;
+        boost::asio::read(socket_, boost::asio::buffer(data, sizeof(data)), ec);
+
+        // Revert the original non_blocking flag on the socket.
+        socket_.non_blocking(non_blocking_orig);
+
+        // If the connection is closed we'd typically get eof status code.
+        return (ec.value() == boost::asio::error::eof);
+    }
+
+    /// @brief Close connection.
+    void close() {
+        socket_.close();
+    }
+
+    std::string getResponse() const {
+        return (response_);
+    }
+
+private:
+
+    /// @brief Holds reference to the IO service.
+    boost::asio::io_service& io_service_;
+
+    /// @brief A socket used for the connection.
+    boost::asio::ip::tcp::socket socket_;
+
+    /// @brief Buffer into which response is written.
+    std::array<char, 8192> buf_;
+
+    /// @brief Response in the textual format.
+    std::string response_;
+};
+
+/// @brief Pointer to the TestHttpClient.
+typedef boost::shared_ptr<TestHttpClient> TestHttpClientPtr;
+
+/// @brief Test fixture class for @ref HttpListener.
+class HttpsListenerTest : public ::testing::Test {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// Starts test timer which detects timeouts.
+    HttpsListenerTest()
+        : io_service_(), factory_(new TestHttpResponseCreatorFactory()),
+          test_timer_(io_service_), run_io_service_timer_(io_service_), clients_() {
+        test_timer_.setup(std::bind(&HttpsListenerTest::timeoutHandler, this, true),
+                          TEST_TIMEOUT, IntervalTimer::ONE_SHOT);
+    }
+
+    /// @brief Destructor.
+    ///
+    /// Removes active HTTP clients.
+    virtual ~HttpsListenerTest() {
+        for (auto client = clients_.begin(); client != clients_.end();
+             ++client) {
+            (*client)->close();
+        }
+    }
+
+    /// @brief Connect to the endpoint.
+    ///
+    /// This method creates TestHttpClient instance and retains it in the clients_
+    /// list.
+    ///
+    /// @param request String containing the HTTP request to be sent.
+    void startRequest(const std::string& request) {
+        TestHttpClientPtr client(new TestHttpClient(io_service_));
+        clients_.push_back(client);
+        clients_.back()->startRequest(request);
+    }
+
+    /// @brief Callback function invoke upon test timeout.
+    ///
+    /// It stops the IO service and reports test timeout.
+    ///
+    /// @param fail_on_timeout Specifies if test failure should be reported.
+    void timeoutHandler(const bool fail_on_timeout) {
+        if (fail_on_timeout) {
+            ADD_FAILURE() << "Timeout occurred while running the test!";
+        }
+        io_service_.stop();
+    }
+
+    /// @brief Runs IO service with optional timeout.
+    ///
+    /// @param timeout Optional value specifying for how long the io service
+    /// should be ran.
+    void runIOService(long timeout = 0) {
+        io_service_.get_io_service().reset();
+
+        if (timeout > 0) {
+            run_io_service_timer_.setup(std::bind(&HttpsListenerTest::timeoutHandler,
+                                                  this, false),
+                                        timeout, IntervalTimer::ONE_SHOT);
+        }
+        io_service_.run();
+        io_service_.get_io_service().reset();
+        io_service_.poll();
+    }
+
+    /// @brief Returns HTTP OK response expected by unit tests.
+    ///
+    /// @param http_version HTTP version.
+    ///
+    /// @return HTTP OK response expected by unit tests.
+    std::string httpOk(const HttpVersion& http_version) {
+        std::ostringstream s;
+        s << "HTTP/" << http_version.major_ << "." << http_version.minor_ << " 200 OK\r\n"
+            "Content-Length: 4\r\n"
+            "Content-Type: application/json\r\n"
+            "Date: Tue, 19 Dec 2016 18:53:35 GMT\r\n"
+            "\r\n"
+            "{  }";
+        return (s.str());
+    }
+
+    /// @brief Tests that HTTP request timeout status is returned when the
+    /// server does not receive the entire request.
+    ///
+    /// @param request Partial request for which the parser will be waiting for
+    /// the next chunks of data.
+    /// @param expected_version HTTP version expected in the response.
+    void testRequestTimeout(const std::string& request,
+                            const HttpVersion& expected_version) {
+        // Open the listener with the Request Timeout of 1 sec and post the
+        // partial request.
+        TlsContextPtr context;
+        HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS),
+                              SERVER_PORT, context,
+                              factory_, HttpListener::RequestTimeout(1000),
+                              HttpListener::IdleTimeout(IDLE_TIMEOUT));
+        ASSERT_NO_THROW(listener.start());
+        ASSERT_NO_THROW(startRequest(request));
+        ASSERT_NO_THROW(runIOService());
+        ASSERT_EQ(1, clients_.size());
+        TestHttpClientPtr client = *clients_.begin();
+        ASSERT_TRUE(client);
+
+        // Build the reference response.
+        std::ostringstream expected_response;
+        expected_response
+            << "HTTP/" << expected_version.major_ << "." << expected_version.minor_
+            << " 408 Request Timeout\r\n"
+            "Content-Length: 44\r\n"
+            "Content-Type: application/json\r\n"
+            "Date: Tue, 19 Dec 2016 18:53:35 GMT\r\n"
+            "\r\n"
+            "{ \"result\": 408, \"text\": \"Request Timeout\" }";
+
+        // The server should wait for the missing part of the request for 1 second.
+        // The missing part never arrives so the server should respond with the
+        // HTTP Request Timeout status.
+        EXPECT_EQ(expected_response.str(), client->getResponse());
+    }
+
+    /// @brief Tests various cases when unexpected data is passed to the
+    /// socket write handler.
+    ///
+    /// This test uses the custom listener and the test specific derivations of
+    /// the @c HttpConnection class to enforce injection of the unexpected
+    /// data to the socket write callback. The two example applications of
+    /// this test are:
+    /// - injecting greater length value than the output buffer size,
+    /// - replacing the transaction with another transaction.
+    ///
+    /// It is expected that the socket write callback deals gracefully with
+    /// those situations.
+    ///
+    /// @tparam HttpConnectionType Test specific derivation of the
+    /// @c HttpConnection class.
+    template<typename HttpConnectionType>
+    void testWriteBufferIssues() {
+        // The HTTP/1.1 requests are by default persistent.
+        std::string request = "POST /foo/bar HTTP/1.1\r\n"
+            "Content-Type: application/json\r\n"
+            "Content-Length: 3\r\n\r\n"
+            "{ }";
+
+        // Use custom listener and the specialized connection object.
+        TlsContextPtr context;
+        HttpListenerCustom<HttpConnectionType>
+            listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                     context, factory_,
+                     HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                     HttpListener::IdleTimeout(IDLE_TIMEOUT));
+
+        ASSERT_NO_THROW(listener.start());
+
+        // Send the request.
+        ASSERT_NO_THROW(startRequest(request));
+
+        // Injecting unexpected data should not result in an exception.
+        ASSERT_NO_THROW(runIOService());
+
+        ASSERT_EQ(1, clients_.size());
+        TestHttpClientPtr client = *clients_.begin();
+        ASSERT_TRUE(client);
+        EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+    }
+
+    /// @brief IO service used in the tests.
+    IOService io_service_;
+
+    /// @brief Pointer to the response creator factory.
+    HttpResponseCreatorFactoryPtr factory_;
+
+    /// @brief Asynchronous timer service to detect timeouts.
+    IntervalTimer test_timer_;
+
+    /// @brief Asynchronous timer for running IO service for a specified amount
+    /// of time.
+    IntervalTimer run_io_service_timer_;
+
+    /// @brief List of client connections.
+    std::list<TestHttpClientPtr> clients_;
+};
+
+// This test verifies that HTTP connection can be established and used to
+// transmit HTTP request and receive a response.
+TEST_F(HttpsListenerTest, listen) {
+    const std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+    ASSERT_NO_THROW(listener.start());
+    ASSERT_EQ(SERVER_ADDRESS, listener.getLocalAddress().toText());
+    ASSERT_EQ(SERVER_PORT, listener.getLocalPort());
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+
+// This test verifies that persistent HTTP connection can be established when
+// "Connection: Keep-Alive" header value is specified.
+TEST_F(HttpsListenerTest, keepAlive) {
+
+    // The first request contains the keep-alive header which instructs the server
+    // to maintain the TCP connection after sending a response.
+    std::string request = "POST /foo/bar HTTP/1.0\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n"
+        "Connection: Keep-Alive\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+
+    ASSERT_NO_THROW(listener.start());
+
+    // Send the request with the keep-alive header.
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_10()), client->getResponse());
+
+    // We have sent keep-alive header so we expect that the connection with
+    // the server remains active.
+    ASSERT_TRUE(client->isConnectionAlive());
+
+    // Test that we can send another request via the same connection. This time
+    // it lacks the keep-alive header, so the server should close the connection
+    // after sending the response.
+    request = "POST /foo/bar HTTP/1.0\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    // Send request reusing the existing connection.
+    ASSERT_NO_THROW(client->sendRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_10()), client->getResponse());
+
+    // Connection should have been closed by the server.
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+// This test verifies that persistent HTTP connection is established by default
+// when HTTP/1.1 is in use.
+TEST_F(HttpsListenerTest, persistentConnection) {
+
+    // The HTTP/1.1 requests are by default persistent.
+    std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+
+    ASSERT_NO_THROW(listener.start());
+
+    // Send the first request.
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    // HTTP/1.1 connection is persistent by default.
+    ASSERT_TRUE(client->isConnectionAlive());
+
+    // Test that we can send another request via the same connection. This time
+    // it includes the "Connection: close" header which instructs the server to
+    // close the connection after responding.
+    request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n"
+        "Connection: close\r\n\r\n"
+        "{ }";
+
+    // Send request reusing the existing connection.
+    ASSERT_NO_THROW(client->sendRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    // Connection should have been closed by the server.
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+// This test verifies that "keep-alive" connection is closed by the server after
+// an idle time.
+TEST_F(HttpsListenerTest, keepAliveTimeout) {
+
+    // The first request contains the keep-alive header which instructs the server
+    // to maintain the TCP connection after sending a response.
+    std::string request = "POST /foo/bar HTTP/1.0\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n"
+        "Connection: Keep-Alive\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    // Specify the idle timeout of 500ms.
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(500));
+
+    ASSERT_NO_THROW(listener.start());
+
+    // Send the request with the keep-alive header.
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_10()), client->getResponse());
+
+    // We have sent keep-alive header so we expect that the connection with
+    // the server remains active.
+    ASSERT_TRUE(client->isConnectionAlive());
+
+    // Run IO service for 1000ms. The idle time is set to 500ms, so the connection
+    // should be closed by the server while we wait here.
+    runIOService(1000);
+
+    // Make sure the connection has been closed.
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    // Check if we can re-establish the connection and send another request.
+    clients_.clear();
+    request = "POST /foo/bar HTTP/1.0\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_10()), client->getResponse());
+
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+// This test verifies that persistent connection is closed by the server after
+// an idle time.
+TEST_F(HttpsListenerTest, persistentConnectionTimeout) {
+
+    // The HTTP/1.1 requests are by default persistent.
+    std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    // Specify the idle timeout of 500ms.
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(500));
+
+    ASSERT_NO_THROW(listener.start());
+
+    // Send the request.
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    // The connection should remain active.
+    ASSERT_TRUE(client->isConnectionAlive());
+
+    // Run IO service for 1000ms. The idle time is set to 500ms, so the connection
+    // should be closed by the server while we wait here.
+    runIOService(1000);
+
+    // Make sure the connection has been closed.
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    // Check if we can re-establish the connection and send another request.
+    clients_.clear();
+    request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n"
+        "Connection: close\r\n\r\n"
+        "{ }";
+
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+// This test verifies that HTTP/1.1 connection remains open even if there is an
+// error in the message body.
+TEST_F(HttpsListenerTest, persistentConnectionBadBody) {
+
+    // The HTTP/1.1 requests are by default persistent.
+    std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 12\r\n\r\n"
+        "{ \"a\": abc }";
+
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+
+    ASSERT_NO_THROW(listener.start());
+
+    // Send the request.
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ("HTTP/1.1 400 Bad Request\r\n"
+              "Content-Length: 40\r\n"
+              "Content-Type: application/json\r\n"
+              "Date: Tue, 19 Dec 2016 18:53:35 GMT\r\n"
+              "\r\n"
+              "{ \"result\": 400, \"text\": \"Bad Request\" }",
+              client->getResponse());
+
+    // The connection should remain active.
+    ASSERT_TRUE(client->isConnectionAlive());
+
+    // Make sure that we can send another request. This time we specify the
+    // "close" connection-token to force the connection to close.
+    request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length: 3\r\n"
+        "Connection: close\r\n\r\n"
+        "{ }";
+
+    // Send request reusing the existing connection.
+    ASSERT_NO_THROW(client->sendRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    EXPECT_EQ(httpOk(HttpVersion::HTTP_11()), client->getResponse());
+
+    EXPECT_TRUE(client->isConnectionClosed());
+
+    listener.stop();
+    io_service_.poll();
+}
+
+// This test verifies that the HTTP listener can't be started twice.
+TEST_F(HttpsListenerTest, startTwice) {
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+    ASSERT_NO_THROW(listener.start());
+    EXPECT_THROW(listener.start(), HttpListenerError);
+}
+
+// This test verifies that Bad Request status is returned when the request
+// is malformed.
+TEST_F(HttpsListenerTest, badRequest) {
+    // Content-Type is wrong. This should result in Bad Request status.
+    const std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: foo\r\n"
+        "Content-Length: 3\r\n\r\n"
+        "{ }";
+
+    TlsContextPtr context;
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS), SERVER_PORT,
+                          context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+    ASSERT_NO_THROW(listener.start());
+    ASSERT_NO_THROW(startRequest(request));
+    ASSERT_NO_THROW(runIOService());
+    ASSERT_EQ(1, clients_.size());
+    TestHttpClientPtr client = *clients_.begin();
+    ASSERT_TRUE(client);
+    EXPECT_EQ("HTTP/1.1 400 Bad Request\r\n"
+              "Content-Length: 40\r\n"
+              "Content-Type: application/json\r\n"
+              "Date: Tue, 19 Dec 2016 18:53:35 GMT\r\n"
+              "\r\n"
+              "{ \"result\": 400, \"text\": \"Bad Request\" }",
+              client->getResponse());
+}
+
+// This test verifies that NULL pointer can't be specified for the
+// HttpResponseCreatorFactory.
+TEST_F(HttpsListenerTest, invalidFactory) {
+    TlsContextPtr context;
+    EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
+                              SERVER_PORT, context,
+                              HttpResponseCreatorFactoryPtr(),
+                              HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                              HttpListener::IdleTimeout(IDLE_TIMEOUT)),
+                 HttpListenerError);
+}
+
+// This test verifies that the timeout of 0 can't be specified for the
+// Request Timeout.
+TEST_F(HttpsListenerTest, invalidRequestTimeout) {
+    TlsContextPtr context;
+    EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
+                              SERVER_PORT, context, factory_,
+                              HttpListener::RequestTimeout(0),
+                              HttpListener::IdleTimeout(IDLE_TIMEOUT)),
+                 HttpListenerError);
+}
+
+// This test verifies that the timeout of 0 can't be specified for the
+// idle persistent connection timeout.
+TEST_F(HttpsListenerTest, invalidIdleTimeout) {
+    TlsContextPtr context;
+    EXPECT_THROW(HttpListener(io_service_, IOAddress(SERVER_ADDRESS),
+                              SERVER_PORT, context, factory_,
+                              HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                              HttpListener::IdleTimeout(0)),
+                 HttpListenerError);
+}
+
+// This test verifies that listener can't be bound to the port to which
+// other server is bound.
+TEST_F(HttpsListenerTest, addressInUse) {
+    tcp::acceptor acceptor(io_service_.get_io_service());
+    // Use other port than SERVER_PORT to make sure that this TCP connection
+    // doesn't affect subsequent tests.
+    tcp::endpoint endpoint(address::from_string(SERVER_ADDRESS),
+                           SERVER_PORT + 1);
+    acceptor.open(endpoint.protocol());
+    acceptor.bind(endpoint);
+
+    TlsContextPtr context;
+    // Listener should report an error when we try to start it because another
+    // acceptor is bound to that port and address.
+    HttpListener listener(io_service_, IOAddress(SERVER_ADDRESS),
+                          SERVER_PORT + 1, context, factory_,
+                          HttpListener::RequestTimeout(REQUEST_TIMEOUT),
+                          HttpListener::IdleTimeout(IDLE_TIMEOUT));
+    EXPECT_THROW(listener.start(), HttpListenerError);
+}
+
+// This test verifies that HTTP Request Timeout status is returned as
+// expected when the read part of the request contains the HTTP
+// version number. The timeout response should contain the same
+// HTTP version number as the partial request.
+TEST_F(HttpsListenerTest, requestTimeoutHttpVersionFound) {
+    // The part of the request specified here is correct but it is not
+    // a complete request.
+    const std::string request = "POST /foo/bar HTTP/1.1\r\n"
+        "Content-Type: application/json\r\n"
+        "Content-Length:";
+
+    testRequestTimeout(request, HttpVersion::HTTP_11());
+}
+
+// This test verifies that HTTP Request Timeout status is returned as
+// expected when the read part of the request does not contain
+// the HTTP version number. The timeout response should by default
+// contain HTTP/1.0 version number.
+TEST_F(HttpsListenerTest, requestTimeoutHttpVersionNotFound) {
+    // The part of the request specified here is correct but it is not
+    // a complete request.
+    const std::string request = "POST /foo/bar HTTP";
+
+    testRequestTimeout(request, HttpVersion::HTTP_10());
+}
+
+// This test verifies that injecting length value greater than the
+// output buffer length to the socket write callback does not cause
+// an exception.
+TEST_F(HttpsListenerTest, tooLongWriteBuffer) {
+    testWriteBufferIssues<HttpConnectionLongWriteBuffer>();
+}
+
+// This test verifies that changing the transaction before calling
+// the socket write callback does not cause an exception.
+TEST_F(HttpsListenerTest, transactionChangeDuringWrite) {
+    testWriteBufferIssues<HttpConnectionTransactionChange>();
+}
+
+}