[master] Merge branch 'master' of ssh://git.kea.isc.org/git/kea

13 files changed, 924 insertions, 100 deletions

diff --git a/ChangeLog b/ChangeLog
index c08bd4d4b4..cddda3fbbd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+1269.	[func]		marcin
+	Command manager can now handle large responses to control
+	commands. Prior to this change the size of the response
+	was limited to 64k. The server now also signals timeout
+	after 10s if the connection lasts too long.
+	(Trac #5318, git 8531a65521ea42f01f3bed444b054e92f7bd1a46)
+
 1268.	[func]		fdupont
 	Kea now re-detects network interfaces every time configuration is
 	changed. 're-detect' parameter added to restore old behavior, if
diff --git a/doc/guide/ctrl-channel.xml b/doc/guide/ctrl-channel.xml
index 5a9ce5bc73..8a0e7ad3b1 100644
--- a/doc/guide/ctrl-channel.xml
+++ b/doc/guide/ctrl-channel.xml
@@ -60,6 +60,20 @@
     it on its own.
     </para>
 
+    <para>Control connections over both HTTP and unix domain sockets are
+    guarded with timeouts. The default timeout value is set to 10s
+    and is not configurable. The timeout configuration will be
+    implemented in the future.
+    </para>
+
+    <note>
+      <simpara>Kea 1.2.0 release and earlier had a limitation of 64kB
+      on the maximum size of a command and a response sent over the unix
+      domain socket. This limitation has been removed in Kea 1.3.0
+      release.
+      </simpara>
+    </note>
+
     <section id="ctrl-channel-syntax">
     <title>Data Syntax</title>
     <para>Communication over the control channel is conducted using JSON
diff --git a/src/bin/dhcp4/tests/ctrl_dhcp4_srv_unittest.cc b/src/bin/dhcp4/tests/ctrl_dhcp4_srv_unittest.cc
index c831f4e038..78418fdaff 100644
--- a/src/bin/dhcp4/tests/ctrl_dhcp4_srv_unittest.cc
+++ b/src/bin/dhcp4/tests/ctrl_dhcp4_srv_unittest.cc
@@ -6,6 +6,7 @@
 
 #include <config.h>
 
+#include <asiolink/interval_timer.h>
 #include <asiolink/io_service.h>
 #include <cc/command_interpreter.h>
 #include <config/command_mgr.h>
@@ -27,9 +28,12 @@
 #include <boost/scoped_ptr.hpp>
 #include <gtest/gtest.h>
 
+#include <cstdlib>
 #include <fstream>
+#include <iomanip>
 #include <iostream>
 #include <sstream>
+#include <thread>
 
 #include <arpa/inet.h>
 #include <unistd.h>
@@ -47,6 +51,32 @@ using namespace isc::test;
 
 namespace {
 
+/// @brief Simple RAII class which stops IO service upon destruction
+/// of the object.
+class IOServiceWork {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// @param io_service Pointer to the IO service to be stopped.
+    IOServiceWork(const IOServicePtr& io_service)
+        : io_service_(io_service) {
+    }
+
+    /// @brief Destructor.
+    ///
+    /// Stops IO service.
+    ~IOServiceWork() {
+        io_service_->stop();
+    }
+
+private:
+
+    /// @brief Pointer to the IO service to be stopped upon destruction.
+    IOServicePtr io_service_;
+
+};
+
 class NakedControlledDhcpv4Srv: public ControlledDhcpv4Srv {
     // "Naked" DHCPv4 server, exposes internal fields
 public:
@@ -58,6 +88,9 @@ public:
     using Dhcpv4Srv::receivePacket;
 };
 
+/// @brief Default control connection timeout.
+const size_t DEFAULT_CONNECTION_TIMEOUT = 10;
+
 /// @brief Fixture class intended for testin control channel in the DHCPv4Srv
 class CtrlChannelDhcpv4SrvTest : public ::testing::Test {
 public:
@@ -87,6 +120,8 @@ public:
         StatsMgr::instance().removeAll();
 
         CommandMgr::instance().closeCommandSocket();
+        CommandMgr::instance().deregisterAll();
+        CommandMgr::instance().setConnectionTimeout(DEFAULT_CONNECTION_TIMEOUT);
 
         server_.reset();
     };
@@ -298,6 +333,54 @@ public:
             ADD_FAILURE() << "Invalid expected status: " << exp_status;
         }
     }
+
+    /// @brief Handler for long command.
+    ///
+    /// It checks whether the received command is equal to the one specified
+    /// as an argument.
+    ///
+    /// @param expected_command String representing an expected command.
+    /// @param command_name Command name received by the handler.
+    /// @param arguments Command arguments received by the handler.
+    ///
+    /// @returns Success answer.
+    static ConstElementPtr
+    longCommandHandler(const std::string& expected_command,
+                       const std::string& command_name,
+                       const ConstElementPtr& arguments) {
+        // The handler is called with a command name and the structure holding
+        // command arguments. We have to rebuild the command from those
+        // two arguments so as it can be compared against expected_command.
+        ElementPtr entire_command = Element::createMap();
+        entire_command->set("command", Element::create(command_name));
+        entire_command->set("arguments", (arguments));
+
+        // The rebuilt command will have a different order of parameters so
+        // let's parse expected_command back to JSON to guarantee that
+        // both structures are built using the same order.
+        EXPECT_EQ(Element::fromJSON(expected_command)->str(),
+                  entire_command->str());
+        return (createAnswer(0, "long command received ok"));
+    }
+
+    /// @brief Command handler which generates long response
+    ///
+    /// This handler generates a large response (over 400kB). It includes
+    /// a list of randomly generated strings to make sure that the test
+    /// can catch out of order delivery.
+    static ConstElementPtr longResponseHandler(const std::string&,
+                                               const ConstElementPtr&) {
+        // By seeding the generator with the constant value we will always
+        // get the same sequence of generated strings.
+        std::srand(1);
+        ElementPtr arguments = Element::createList();
+        for (unsigned i = 0; i < 40000; ++i) {
+            std::ostringstream s;
+            s << std::setw(10) << std::rand();
+            arguments->add(Element::create(s.str()));
+        }
+        return (createAnswer(0, arguments));
+    }
 };
 
 TEST_F(CtrlChannelDhcpv4SrvTest, commands) {
@@ -433,7 +516,7 @@ TEST_F(CtrlChannelDhcpv4SrvTest, controlChannelNegative) {
 
     sendUnixCommand("utter nonsense", response);
     EXPECT_EQ("{ \"result\": 1, "
-              "\"text\": \"error: unexpected character u in <string>:1:2\" }",
+              "\"text\": \"invalid first character u\" }",
               response);
 }
 
@@ -712,7 +795,7 @@ TEST_F(CtrlChannelDhcpv4SrvTest, configSet) {
     // Should fail with a syntax error
     EXPECT_EQ("{ \"result\": 1, "
               "\"text\": \"subnet configuration failed: mandatory 'subnet' "
-              "parameter is missing for a subnet being configured (<string>:20:17)\" }",
+              "parameter is missing for a subnet being configured (<wire>:19:17)\" }",
               response);
 
     // Check that the config was not lost
@@ -911,7 +994,7 @@ TEST_F(CtrlChannelDhcpv4SrvTest, configTest) {
     // Should fail with a syntax error
     EXPECT_EQ("{ \"result\": 1, "
               "\"text\": \"subnet configuration failed: mandatory 'subnet' "
-              "parameter is missing for a subnet being configured (<string>:20:17)\" }",
+              "parameter is missing for a subnet being configured (<wire>:19:17)\" }",
               response);
 
     // Check that the config was not lost
@@ -952,7 +1035,7 @@ TEST_F(CtrlChannelDhcpv4SrvTest, configTest) {
     // Clean up after the test.
     CfgMgr::instance().clear();
 }
-                    
+
 // Tests if config-write can be called without any parameters.
 TEST_F(CtrlChannelDhcpv4SrvTest, writeConfigNoFilename) {
     createUnixChannelServer();
@@ -1110,4 +1193,213 @@ TEST_F(CtrlChannelDhcpv4SrvTest, concurrentConnections) {
     ASSERT_NO_THROW(getIOService()->poll());
 }
 
+// This test verifies that the server can receive and process a large command.
+TEST_F(CtrlChannelDhcpv4SrvTest, longCommand) {
+
+    std::ostringstream command;
+
+    // This is the desired size of the command sent to the server (1MB). The
+    // actual size sent will be slightly greater than that.
+    const size_t command_size = 1024 * 1000;
+
+    while (command.tellp() < command_size) {
+
+        // We're sending command 'foo' with arguments being a list of
+        // strings. If this is the first transmission, send command name
+        // and open the arguments list. Also insert the first argument
+        // so as all subsequent arguments can be prefixed with a comma.
+        if (command.tellp() == 0) {
+            command << "{ \"command\": \"foo\", \"arguments\": [ \"begin\"";
+
+        } else {
+            // Generate a random number and insert it into the stream as
+            // 10 digits long string.
+            std::ostringstream arg;
+            arg << setw(10) << std::rand();
+            // Append the argument in the command.
+            command << ", \"" << arg.str() << "\"\n";
+
+            // If we have hit the limit of the command size, close braces to
+            // get appropriate JSON.
+            if (command.tellp() > command_size) {
+                command << "] }";
+            }
+        }
+    }
+
+    ASSERT_NO_THROW(
+        CommandMgr::instance().registerCommand("foo",
+             boost::bind(&CtrlChannelDhcpv4SrvTest::longCommandHandler,
+                         command.str(), _1, _2));
+    );
+
+    createUnixChannelServer();
+
+    std::string response;
+    std::thread th([this, &response, &command]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Create client which we will use to send command to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+
+        // Connect to the server. This will trigger acceptor handler on the
+        // server side and create a new connection.
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Initially the remaining_string holds the entire command and we
+        // will be erasing the portions that we have sent.
+        std::string remaining_data = command.str();
+        while (!remaining_data.empty()) {
+            // Send the command in chunks of 1024 bytes.
+            const size_t l = remaining_data.size() < 1024 ? remaining_data.size() : 1024;
+            ASSERT_TRUE(client->sendCommand(remaining_data.substr(0, l)));
+            remaining_data.erase(0, l);
+        }
+
+        // Set timeout to 5 seconds to allow the time for the server to send
+        // a response.
+        const unsigned int timeout = 5;
+        ASSERT_TRUE(client->getResponse(response, timeout));
+
+        // We're done. Close the connection to the server.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until the command has been processed and response
+    // received.
+    getIOService()->run();
+
+    // Wait for the thread to complete.
+    th.join();
+
+    EXPECT_EQ("{ \"result\": 0, \"text\": \"long command received ok\" }",
+              response);
+}
+
+// This test verifies that the server can send long response to the client.
+TEST_F(CtrlChannelDhcpv4SrvTest, longResponse) {
+    // We need to generate large response. The simplest way is to create
+    // a command and a handler which will generate some static response
+    // of a desired size.
+    ASSERT_NO_THROW(
+        CommandMgr::instance().registerCommand("foo",
+             boost::bind(&CtrlChannelDhcpv4SrvTest::longResponseHandler, _1, _2));
+    );
+
+    createUnixChannelServer();
+
+    // The UnixControlClient doesn't have any means to check that the entire
+    // response has been received. What we want to do is to generate a
+    // reference response using our command handler and then compare
+    // what we have received over the unix domain socket with this reference
+    // response to figure out when to stop receiving.
+    std::string reference_response = longResponseHandler("foo", ConstElementPtr())->str();
+
+    // In this stream we're going to collect out partial responses.
+    std::ostringstream response;
+
+    // The client is synchronous so it is useful to run it in a thread.
+    std::thread th([this, &response, reference_response]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Remember the response size so as we know when we should stop
+        // receiving.
+        const size_t long_response_size = reference_response.size();
+
+        // Create the client and connect it to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Send the stub command.
+        std::string command = "{ \"command\": \"foo\", \"arguments\": { }  }";
+        ASSERT_TRUE(client->sendCommand(command));
+
+        // Keep receiving response data until we have received the full answer.
+        while (response.tellp() < long_response_size) {
+            std::string partial;
+            const unsigned int timeout = 5;
+            ASSERT_TRUE(client->getResponse(partial, 5));
+            response << partial;
+        }
+
+        // We have received the entire response, so close the connection and
+        // stop the IO service.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until the entire response has been received.
+    getIOService()->run();
+
+    // Wait for the thread to complete.
+    th.join();
+
+    // Make sure we have received correct response.
+    EXPECT_EQ(reference_response, response.str());
+}
+
+// This test verifies that the server signals timeout if the transmission
+// takes too long.
+TEST_F(CtrlChannelDhcpv4SrvTest, connectionTimeout) {
+    createUnixChannelServer();
+
+    // Set connection timeout to 2s to prevent long waiting time for the
+    // timeout during this test.
+    const unsigned short timeout = 2;
+    CommandMgr::instance().setConnectionTimeout(timeout);
+
+    // Server's response will be assigned to this variable.
+    std::string response;
+
+    // It is useful to create a thread and run the server and the client
+    // at the same time and independently.
+    std::thread th([this, &response]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Create the client and connect it to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Send partial command. The server will be waiting for the remaining
+        // part to be sent and will eventually signal a timeout.
+        std::string command = "{ \"command\": \"foo\" ";
+        ASSERT_TRUE(client->sendCommand(command));
+
+        // Let's wait up to 15s for the server's response. The response
+        // should arrive sooner assuming that the timeout mechanism for
+        // the server is working properly.
+        const unsigned int timeout = 15;
+        ASSERT_TRUE(client->getResponse(response, timeout));
+
+        // Explicitly close the client's connection.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until stopped.
+    getIOService()->run();
+
+    // Wait for the thread to return.
+    th.join();
+
+    // Check that the server has signalled a timeout.
+    EXPECT_EQ("{ \"result\": 1, \"text\": \"Connection over control channel"
+              " timed out\" }", response);
+}
+
+
+
 } // End of anonymous namespace
diff --git a/src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc b/src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc
index b16ae7826e..2214ebe5c4 100644
--- a/src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc
+++ b/src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc
@@ -26,11 +26,16 @@
 #include <boost/scoped_ptr.hpp>
 #include <gtest/gtest.h>
 
+#include <iomanip>
+#include <sstream>
+
 #include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <cstdlib>
 
+#include <thread>
+
 using namespace std;
 using namespace isc::asiolink;
 using namespace isc::config;
@@ -43,7 +48,31 @@ using namespace isc::test;
 
 namespace {
 
+/// @brief Simple RAII class which stops IO service upon destruction
+/// of the object.
+class IOServiceWork {
+public:
 
+    /// @brief Constructor.
+    ///
+    /// @param io_service Pointer to the IO service to be stopped.
+    IOServiceWork(const IOServicePtr& io_service)
+        : io_service_(io_service) {
+    }
+
+    /// @brief Destructor.
+    ///
+    /// Stops IO service.
+    ~IOServiceWork() {
+        io_service_->stop();
+    }
+
+private:
+
+    /// @brief Pointer to the IO service to be stopped upon destruction.
+    IOServicePtr io_service_;
+
+};
 
 class NakedControlledDhcpv6Srv: public ControlledDhcpv6Srv {
     // "Naked" DHCPv6 server, exposes internal fields
@@ -56,6 +85,9 @@ public:
     using Dhcpv6Srv::receivePacket;
 };
 
+/// @brief Default control connection timeout.
+const size_t DEFAULT_CONNECTION_TIMEOUT = 10;
+
 class CtrlDhcpv6SrvTest : public BaseServerTest {
 public:
     CtrlDhcpv6SrvTest()
@@ -66,6 +98,9 @@ public:
     virtual ~CtrlDhcpv6SrvTest() {
         LeaseMgrFactory::destroy();
         StatsMgr::instance().removeAll();
+        CommandMgr::instance().deregisterAll();
+        CommandMgr::instance().setConnectionTimeout(DEFAULT_CONNECTION_TIMEOUT);
+
         reset();
     };
 
@@ -307,6 +342,54 @@ public:
             ADD_FAILURE() << "Invalid expected status: " << exp_status;
         }
     }
+
+    /// @brief Handler for long command.
+    ///
+    /// It checks whether the received command is equal to the one specified
+    /// as an argument.
+    ///
+    /// @param expected_command String representing an expected command.
+    /// @param command_name Command name received by the handler.
+    /// @param arguments Command arguments received by the handler.
+    ///
+    /// @returns Success answer.
+    static ConstElementPtr
+    longCommandHandler(const std::string& expected_command,
+                       const std::string& command_name,
+                       const ConstElementPtr& arguments) {
+        // The handler is called with a command name and the structure holding
+        // command arguments. We have to rebuild the command from those
+        // two arguments so as it can be compared against expected_command.
+        ElementPtr entire_command = Element::createMap();
+        entire_command->set("command", Element::create(command_name));
+        entire_command->set("arguments", (arguments));
+
+        // The rebuilt command will have a different order of parameters so
+        // let's parse expected_command back to JSON to guarantee that
+        // both structures are built using the same order.
+        EXPECT_EQ(Element::fromJSON(expected_command)->str(),
+                  entire_command->str());
+        return (createAnswer(0, "long command received ok"));
+    }
+
+    /// @brief Command handler which generates long response
+    ///
+    /// This handler generates a large response (over 400kB). It includes
+    /// a list of randomly generated strings to make sure that the test
+    /// can catch out of order delivery.
+    static ConstElementPtr longResponseHandler(const std::string&,
+                                               const ConstElementPtr&) {
+        // By seeding the generator with the constant value we will always
+        // get the same sequence of generated strings.
+        std::srand(1);
+        ElementPtr arguments = Element::createList();
+        for (unsigned i = 0; i < 40000; ++i) {
+            std::ostringstream s;
+            s << std::setw(10) << std::rand();
+            arguments->add(Element::create(s.str()));
+        }
+        return (createAnswer(0, arguments));
+    }
 };
 
 
@@ -485,7 +568,7 @@ TEST_F(CtrlChannelDhcpv6SrvTest, configSet) {
 
     // Should fail with a syntax error
     EXPECT_EQ("{ \"result\": 1, "
-              "\"text\": \"subnet configuration failed: mandatory 'subnet' parameter is missing for a subnet being configured (<string>:21:17)\" }",
+              "\"text\": \"subnet configuration failed: mandatory 'subnet' parameter is missing for a subnet being configured (<wire>:20:17)\" }",
               response);
 
     // Check that the config was not lost
@@ -631,7 +714,7 @@ TEST_F(CtrlChannelDhcpv6SrvTest, configTest) {
     // Should fail with a syntax error
     EXPECT_EQ("{ \"result\": 1, "
               "\"text\": \"subnet configuration failed: mandatory 'subnet' parameter "
-              "is missing for a subnet being configured (<string>:21:17)\" }",
+              "is missing for a subnet being configured (<wire>:20:17)\" }",
               response);
 
     // Check that the config was not lost
@@ -738,7 +821,7 @@ TEST_F(CtrlChannelDhcpv6SrvTest, controlChannelNegative) {
 
     sendUnixCommand("utter nonsense", response);
     EXPECT_EQ("{ \"result\": 1, "
-              "\"text\": \"error: unexpected character u in <string>:1:2\" }",
+              "\"text\": \"invalid first character u\" }",
               response);
 }
 
@@ -1131,5 +1214,212 @@ TEST_F(CtrlChannelDhcpv6SrvTest, concurrentConnections) {
     ASSERT_NO_THROW(getIOService()->poll());
 }
 
+// This test verifies that the server can receive and process a large command.
+TEST_F(CtrlChannelDhcpv6SrvTest, longCommand) {
+
+    std::ostringstream command;
+
+    // This is the desired size of the command sent to the server (1MB). The
+    // actual size sent will be slightly greater than that.
+    const size_t command_size = 1024 * 1000;
+
+    while (command.tellp() < command_size) {
+
+        // We're sending command 'foo' with arguments being a list of
+        // strings. If this is the first transmission, send command name
+        // and open the arguments list. Also insert the first argument
+        // so as all subsequent arguments can be prefixed with a comma.
+        if (command.tellp() == 0) {
+            command << "{ \"command\": \"foo\", \"arguments\": [ \"begin\"";
+
+        } else {
+            // Generate a random number and insert it into the stream as
+            // 10 digits long string.
+            std::ostringstream arg;
+            arg << setw(10) << std::rand();
+            // Append the argument in the command.
+            command << ", \"" << arg.str() << "\"\n";
+
+            // If we have hit the limit of the command size, close braces to
+            // get appropriate JSON.
+            if (command.tellp() > command_size) {
+                command << "] }";
+            }
+        }
+    }
+
+    ASSERT_NO_THROW(
+        CommandMgr::instance().registerCommand("foo",
+             boost::bind(&CtrlChannelDhcpv6SrvTest::longCommandHandler,
+                         command.str(), _1, _2));
+    );
+
+    createUnixChannelServer();
+
+    std::string response;
+    std::thread th([this, &response, &command]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Create client which we will use to send command to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+
+        // Connect to the server. This will trigger acceptor handler on the
+        // server side and create a new connection.
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Initially the remaining_string holds the entire command and we
+        // will be erasing the portions that we have sent.
+        std::string remaining_data = command.str();
+        while (!remaining_data.empty()) {
+            // Send the command in chunks of 1024 bytes.
+            const size_t l = remaining_data.size() < 1024 ? remaining_data.size() : 1024;
+            ASSERT_TRUE(client->sendCommand(remaining_data.substr(0, l)));
+            remaining_data.erase(0, l);
+        }
+
+        // Set timeout to 5 seconds to allow the time for the server to send
+        // a response.
+        const unsigned int timeout = 5;
+        ASSERT_TRUE(client->getResponse(response, timeout));
+
+        // We're done. Close the connection to the server.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until the command has been processed and response
+    // received.
+    getIOService()->run();
+
+    // Wait for the thread to complete.
+    th.join();
+
+    EXPECT_EQ("{ \"result\": 0, \"text\": \"long command received ok\" }",
+              response);
+}
+
+// This test verifies that the server can send long response to the client.
+TEST_F(CtrlChannelDhcpv6SrvTest, longResponse) {
+    // We need to generate large response. The simplest way is to create
+    // a command and a handler which will generate some static response
+    // of a desired size.
+    ASSERT_NO_THROW(
+        CommandMgr::instance().registerCommand("foo",
+             boost::bind(&CtrlChannelDhcpv6SrvTest::longResponseHandler, _1, _2));
+    );
+
+    createUnixChannelServer();
+
+    // The UnixControlClient doesn't have any means to check that the entire
+    // response has been received. What we want to do is to generate a
+    // reference response using our command handler and then compare
+    // what we have received over the unix domain socket with this reference
+    // response to figure out when to stop receiving.
+    std::string reference_response = longResponseHandler("foo", ConstElementPtr())->str();
+
+    // In this stream we're going to collect out partial responses.
+    std::ostringstream response;
+
+    // The client is synchronous so it is useful to run it in a thread.
+    std::thread th([this, &response, reference_response]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Remember the response size so as we know when we should stop
+        // receiving.
+        const size_t long_response_size = reference_response.size();
+
+        // Create the client and connect it to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Send the stub command.
+        std::string command = "{ \"command\": \"foo\", \"arguments\": { }  }";
+        ASSERT_TRUE(client->sendCommand(command));
+
+        // Keep receiving response data until we have received the full answer.
+        while (response.tellp() < long_response_size) {
+            std::string partial;
+            const unsigned int timeout = 5;
+            ASSERT_TRUE(client->getResponse(partial, 5));
+            response << partial;
+        }
+
+        // We have received the entire response, so close the connection and
+        // stop the IO service.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until the entire response has been received.
+    getIOService()->run();
+
+    // Wait for the thread to complete.
+    th.join();
+
+    // Make sure we have received correct response.
+    EXPECT_EQ(reference_response, response.str());
+}
+
+// This test verifies that the server signals timeout if the transmission
+// takes too long.
+TEST_F(CtrlChannelDhcpv6SrvTest, connectionTimeout) {
+    createUnixChannelServer();
+
+    // Set connection timeout to 2s to prevent long waiting time for the
+    // timeout during this test.
+    const unsigned short timeout = 2;
+    CommandMgr::instance().setConnectionTimeout(timeout);
+
+    // Server's response will be assigned to this variable.
+    std::string response;
+
+    // It is useful to create a thread and run the server and the client
+    // at the same time and independently.
+    std::thread th([this, &response]() {
+
+        // IO service will be stopped automatically when this object goes
+        // out of scope and is destroyed. This is useful because we use
+        // asserts which may break the thread in various exit points.
+        IOServiceWork work(getIOService());
+
+        // Create the client and connect it to the server.
+        boost::scoped_ptr<UnixControlClient> client(new UnixControlClient());
+        ASSERT_TRUE(client);
+        ASSERT_TRUE(client->connectToServer(socket_path_));
+
+        // Send partial command. The server will be waiting for the remaining
+        // part to be sent and will eventually signal a timeout.
+        std::string command = "{ \"command\": \"foo\" ";
+        ASSERT_TRUE(client->sendCommand(command));
+
+        // Let's wait up to 15s for the server's response. The response
+        // should arrive sooner assuming that the timeout mechanism for
+        // the server is working properly.
+        const unsigned int timeout = 15;
+        ASSERT_TRUE(client->getResponse(response, timeout));
+
+        // Explicitly close the client's connection.
+        client->disconnectFromServer();
+    });
+
+    // Run the server until stopped.
+    getIOService()->run();
+
+    // Wait for the thread to return.
+    th.join();
+
+    // Check that the server has signalled a timeout.
+    EXPECT_EQ("{ \"result\": 1, \"text\": \"Connection over control channel"
+              " timed out\" }", response);
+}
+
 
 } // End of anonymous namespace
diff --git a/src/lib/asiolink/unix_domain_socket.cc b/src/lib/asiolink/unix_domain_socket.cc
index ae639df138..44accc3854 100644
--- a/src/lib/asiolink/unix_domain_socket.cc
+++ b/src/lib/asiolink/unix_domain_socket.cc
@@ -145,6 +145,12 @@ public:
                         const boost::system::error_code& ec,
                         size_t length);
 
+    /// @brief Disables read and write operations on the socket.
+    void shutdown();
+
+    /// @brief Cancels asynchronous operations on the socket.
+    void cancel();
+
     /// @brief Closes the socket.
     void close();
 
@@ -245,8 +251,30 @@ UnixDomainSocketImpl::receiveHandler(const UnixDomainSocket::Handler& remote_han
 }
 
 void
+UnixDomainSocketImpl::shutdown() {
+    boost::system::error_code ec;
+    static_cast<void>(socket_.shutdown(stream_protocol::socket::shutdown_both, ec));
+    if (ec) {
+        isc_throw(UnixDomainSocketError, ec.message());
+    }
+}
+
+void
+UnixDomainSocketImpl::cancel() {
+    boost::system::error_code ec;
+    static_cast<void>(socket_.cancel(ec));
+    if (ec) {
+        isc_throw(UnixDomainSocketError, ec.message());
+    }
+}
+
+void
 UnixDomainSocketImpl::close() {
-    static_cast<void>(socket_.close());
+    boost::system::error_code ec;
+    static_cast<void>(socket_.close(ec));
+    if (ec) {
+        isc_throw(UnixDomainSocketError, ec.message());
+    }
 }
 
 UnixDomainSocket::UnixDomainSocket(IOService& io_service)
@@ -313,6 +341,16 @@ UnixDomainSocket::asyncReceive(void* data, const size_t length,
 }
 
 void
+UnixDomainSocket::shutdown() {
+    impl_->shutdown();
+}
+
+void
+UnixDomainSocket::cancel() {
+    impl_->cancel();
+}
+
+void
 UnixDomainSocket::close() {
     impl_->close();
 }
diff --git a/src/lib/asiolink/unix_domain_socket.h b/src/lib/asiolink/unix_domain_socket.h
index ed8cfdd0ed..e7efe6b1f3 100644
--- a/src/lib/asiolink/unix_domain_socket.h
+++ b/src/lib/asiolink/unix_domain_socket.h
@@ -104,7 +104,19 @@ public:
     /// error is signalled.
     void asyncReceive(void* data, const size_t length, const Handler& handler);
 
+    /// @brief Disables read and write operations on the socket.
+    ///
+    /// @throw UnixDomainSocketError if an error occurs during shutdown.
+    void shutdown();
+
+    /// @brief Cancels scheduled asynchronous operations on the socket.
+    ///
+    /// @throw UnixDomainSocketError if an error occurs during cancel operation.
+    void cancel();
+
     /// @brief Closes the socket.
+    ///
+    /// @throw UnixDomainSocketError if an error occurs during closure.
     void close();
 
     /// @brief Returns reference to the underlying ASIO socket.
diff --git a/src/lib/cc/json_feed.cc b/src/lib/cc/json_feed.cc
index b2491f0d2f..6a039490c4 100644
--- a/src/lib/cc/json_feed.cc
+++ b/src/lib/cc/json_feed.cc
@@ -141,7 +141,7 @@ JSONFeed::defineStates() {
 
 void
 JSONFeed::feedFailure(const std::string& error_msg) {
-    error_message_ = error_msg + " : " + getContextStr();
+    error_message_ = error_msg;
     transition(FEED_FAILED_ST, FEED_FAILED_EVT);
 }
 
diff --git a/src/lib/config/command-socket.dox b/src/lib/config/command-socket.dox
index 1bb5f7e548..798c525980 100644
--- a/src/lib/config/command-socket.dox
+++ b/src/lib/config/command-socket.dox
@@ -163,9 +163,9 @@ or HTTPS connection):
 The @ref isc::config::CommandMgr is implemented using boost ASIO and uses
 asynchronous calls to accept new connections and receive commands from the
 controlling clients. ASIO uses IO service object to run asynchronous calls.
-Thus, before the server can use the @ref isc::dhcp::CommandMgr it must
+Thus, before the server can use the @ref isc::config::CommandMgr it must
 provide it with a common instance of the @ref isc::asiolink::IOService
-object using @ref isc::dhcp::CommandMgr::setIOService. The server's
+object using @ref isc::config::CommandMgr::setIOService. The server's
 main loop must contain calls to @ref isc::asiolink::IOService::run or
 @ref isc::asiolink::IOService::poll or their variants to invoke Command
 Manager's handlers as required for processing control requests.
diff --git a/src/lib/config/command_mgr.cc b/src/lib/config/command_mgr.cc
index 2be8124e94..5c1d2b6ef3 100644
--- a/src/lib/config/command_mgr.cc
+++ b/src/lib/config/command_mgr.cc
@@ -5,6 +5,7 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 #include <asiolink/asio_wrapper.h>
+#include <asiolink/interval_timer.h>
 #include <asiolink/io_service.h>
 #include <asiolink/unix_domain_socket.h>
 #include <asiolink/unix_domain_socket_acceptor.h>
@@ -12,6 +13,7 @@
 #include <config/command_mgr.h>
 #include <cc/data.h>
 #include <cc/command_interpreter.h>
+#include <cc/json_feed.h>
 #include <dhcp/iface_mgr.h>
 #include <config/config_log.h>
 #include <boost/bind.hpp>
@@ -26,6 +28,12 @@ using namespace isc::data;
 
 namespace {
 
+/// @brief Maximum size of the data chunk sent/received over the socket.
+const size_t BUF_SIZE = 8192;
+
+/// @brief Default connection timeout in seconds.
+const unsigned short DEFAULT_CONNECTION_TIMEOUT = 10;
+
 class ConnectionPool;
 
 /// @brief Represents a single connection over control socket.
@@ -40,26 +48,40 @@ public:
     /// This constructor registers a socket of this connection in the Interface
     /// Manager to cause the blocking call to @c select() to return as soon as
     /// a transmission over the control socket is received.
-    Connection(const boost::shared_ptr<UnixDomainSocket>& socket,
-               ConnectionPool& connection_pool)
-        : socket_(socket), connection_pool_(connection_pool),
+    ///
+    /// @param io_service IOService object used to handle the asio operations
+    /// @param socket Pointer to the object representing a socket which is used
+    /// for data transmission.
+    /// @param connection_pool Reference to the connection pool to which this
+    /// connection belongs.
+    /// @param timeout Connection timeout (in seconds).
+    Connection(const IOServicePtr& io_service,
+               const boost::shared_ptr<UnixDomainSocket>& socket,
+               ConnectionPool& connection_pool,
+               const unsigned short timeout)
+        : socket_(socket), timeout_timer_(*io_service), timeout_(timeout),
+          buf_(), response_(), connection_pool_(connection_pool), feed_(),
           response_in_progress_(false) {
+
+        LOG_INFO(command_logger, COMMAND_SOCKET_CONNECTION_OPENED)
+            .arg(socket_->getNative());
+
         // Callback value of 0 is used to indicate that callback function is
         // not installed.
         isc::dhcp::IfaceMgr::instance().addExternalSocket(socket_->getNative(), 0);
+        // Initialize state model for receiving and preparsing commands.
+        feed_.initModel();
+
+        // Start timer for detecting timeouts.
+        timeout_timer_.setup(boost::bind(&Connection::timeoutHandler, this),
+                             timeout_ * 1000, IntervalTimer::ONE_SHOT);
     }
 
-    /// @brief Start asynchronous read over the unix domain socket.
+    /// @brief Destructor.
     ///
-    /// This method doesn't block. Once the transmission is received over the
-    /// socket, the @c Connection::receiveHandler callback is invoked to
-    /// process received data.
-    void start() {
-        socket_->asyncReceive(&buf_[0], sizeof(buf_),
-                              boost::bind(&Connection::receiveHandler,
-                                          shared_from_this(), _1, _2));
-
-
+    /// Cancels timeout timer if one is scheduled.
+    ~Connection() {
+        timeout_timer_.cancel();
     }
 
     /// @brief Close current connection.
@@ -75,28 +97,99 @@ public:
 
             isc::dhcp::IfaceMgr::instance().deleteExternalSocket(socket_->getNative());
             socket_->close();
+            timeout_timer_.cancel();
         }
     }
 
+    /// @brief Gracefully terminates current connection.
+    ///
+    /// This method should be called prior to closing the socket to initiate
+    /// graceful shutdown.
+    void terminate();
+
+    /// @brief Start asynchronous read over the unix domain socket.
+    ///
+    /// This method doesn't block. Once the transmission is received over the
+    /// socket, the @c Connection::receiveHandler callback is invoked to
+    /// process received data.
+    void doReceive() {
+        socket_->asyncReceive(&buf_[0], sizeof(buf_),
+                              boost::bind(&Connection::receiveHandler,
+                                          shared_from_this(), _1, _2));
+
+
+    }
+
+    /// @brief Starts asynchronous send over the unix domain socket.
+    ///
+    /// This method doesn't block. Once the send operation (that covers the whole
+    /// data if it's small or first BUF_SIZE bytes if its large) is completed, the
+    /// @c Connection::sendHandler callback is invoked. That handler will either
+    /// close the connection gracefully if all data has been sent, or will
+    /// call @ref doSend() again to send the next chunk of data.
+    void doSend() {
+        size_t chunk_size = (response_.size() < BUF_SIZE) ? response_.size() : BUF_SIZE;
+        socket_->asyncSend(&response_[0], chunk_size,
+           boost::bind(&Connection::sendHandler, shared_from_this(), _1, _2));
+    }
+
     /// @brief Handler invoked when the data is received over the control
     /// socket.
     ///
+    /// It collects received data into the @c isc::config::JSONFeed object and
+    /// schedules additional asynchronous read of data if this object signals
+    /// that command is incomplete. When the entire command is received, the
+    /// handler processes this command and asynchronously responds to the
+    /// controlling client.
+    //
+    ///
     /// @param ec Error code.
     /// @param bytes_transferred Number of bytes received.
     void receiveHandler(const boost::system::error_code& ec,
                         size_t bytes_transferred);
 
+
+    /// @brief Handler invoked when the data is sent over the control socket.
+    ///
+    /// If there are still data to be sent, another asynchronous send is
+    /// scheduled. When the entire command is sent, the connection is shutdown
+    /// and closed.
+    ///
+    /// @param ec Error code.
+    /// @param bytes_transferred Number of bytes sent.
+    void sendHandler(const boost::system::error_code& ec,
+                     size_t bytes_trasferred);
+
+    /// @brief Handler invoked when timeout has occurred.
+    ///
+    /// Asynchronously sends a response to the client indicating that the
+    /// timeout has occurred.
+    void timeoutHandler();
+
 private:
 
     /// @brief Pointer to the socket used for transmission.
     boost::shared_ptr<UnixDomainSocket> socket_;
 
+    /// @brief Interval timer used to detect connection timeouts.
+    IntervalTimer timeout_timer_;
+
+    /// @brief Connection timeout (in seconds)
+    unsigned short timeout_;
+
     /// @brief Buffer used for received data.
-    std::array<char, 65535> buf_;
+    std::array<char, BUF_SIZE> buf_;
+
+    /// @brief Response created by the server.
+    std::string response_;
 
     /// @brief Reference to the pool of connections.
     ConnectionPool& connection_pool_;
 
+    /// @brief State model used to receive data over the connection and detect
+    /// when the command ends.
+    JSONFeed feed_;
+
     /// @brief Boolean flag indicating if the request to stop connection is a
     /// result of server reconfiguration.
     bool response_in_progress_;
@@ -114,7 +207,7 @@ public:
     ///
     /// @param connection Pointer to the new connection object.
     void start(const ConnectionPtr& connection) {
-        connection->start();
+        connection->doReceive();
         connections_.insert(connection);
     }
 
@@ -122,8 +215,13 @@ public:
     ///
     /// @param connection Pointer to the new connection object.
     void stop(const ConnectionPtr& connection) {
-        connection->stop();
-        connections_.erase(connection);
+        try {
+            connection->stop();
+            connections_.erase(connection);
+        } catch (const std::exception& ex) {
+            LOG_ERROR(command_logger, COMMAND_SOCKET_CONNECTION_CLOSE_FAIL)
+                .arg(ex.what());
+        }
     }
 
     /// @brief Stops all connections which are allowed to stop.
@@ -135,10 +233,6 @@ public:
         connections_.clear();
     }
 
-    size_t getConnectionsNum() const {
-        return (connections_.size());
-    }
-
 private:
 
     /// @brief Pool of connections.
@@ -146,6 +240,16 @@ private:
 
 };
 
+void
+Connection::terminate() {
+    try {
+        socket_->shutdown();
+
+    } catch (const std::exception& ex) {
+        LOG_ERROR(command_logger, COMMAND_SOCKET_CONNECTION_SHUTDOWN_FAIL)
+            .arg(ex.what());
+    }
+}
 
 void
 Connection::receiveHandler(const boost::system::error_code& ec,
@@ -156,15 +260,13 @@ Connection::receiveHandler(const boost::system::error_code& ec,
             // connection pool.
             LOG_INFO(command_logger, COMMAND_SOCKET_CLOSED_BY_FOREIGN_HOST)
                 .arg(socket_->getNative());
-            connection_pool_.stop(shared_from_this());
 
         } else if (ec.value() != boost::asio::error::operation_aborted) {
             LOG_ERROR(command_logger, COMMAND_SOCKET_READ_FAIL)
                 .arg(ec.value()).arg(socket_->getNative());
         }
 
-        /// @todo: Should we close the connection, similar to what is already
-        /// being done for bytes_transferred == 0.
+        connection_pool_.stop(shared_from_this());
         return;
 
     } else if (bytes_transferred == 0) {
@@ -176,21 +278,35 @@ Connection::receiveHandler(const boost::system::error_code& ec,
     LOG_DEBUG(command_logger, DBG_COMMAND, COMMAND_SOCKET_READ)
         .arg(bytes_transferred).arg(socket_->getNative());
 
-    ConstElementPtr cmd, rsp;
+    ConstElementPtr rsp;
 
     try {
+        // Received some data over the socket. Append them to the JSON feed
+        // to see if we have reached the end of command.
+        feed_.postBuffer(&buf_[0], bytes_transferred);
+        feed_.poll();
+        // If we haven't yet received the full command, continue receiving.
+        if (feed_.needData()) {
+            doReceive();
+            return;
+        }
 
-        // Try to interpret it as JSON.
-        std::string sbuf(&buf_[0], bytes_transferred);
-        cmd = Element::fromJSON(sbuf, true);
-
-        response_in_progress_ = true;
+        // Received entire command. Parse the command into JSON.
+        if (feed_.feedOk()) {
+            ConstElementPtr cmd = feed_.toElement();
+            response_in_progress_ = true;
 
-        // If successful, then process it as a command.
-        rsp = CommandMgr::instance().processCommand(cmd);
+            // If successful, then process it as a command.
+            rsp = CommandMgr::instance().processCommand(cmd);
 
-        response_in_progress_ = false;
+            response_in_progress_ = false;
 
+        } else {
+            // Failed to parse command as JSON or process the received command.
+            // This exception will be caught below and the error response will
+            // be sent.
+            isc_throw(BadValue, feed_.getErrorMessage());
+        }
 
     } catch (const Exception& ex) {
         LOG_WARN(command_logger, COMMAND_PROCESS_ERROR1).arg(ex.what());
@@ -203,35 +319,76 @@ Connection::receiveHandler(const boost::system::error_code& ec,
         rsp = createAnswer(CONTROL_RESULT_ERROR,
                            "internal server error: no response generated");
 
+    } else {
+
+        // Let's convert JSON response to text. Note that at this stage
+        // the rsp pointer is always set.
+        response_ = rsp->str();
+
+        doSend();
+        return;
     }
 
-    // Let's convert JSON response to text. Note that at this stage
-    // the rsp pointer is always set.
-    std::string txt = rsp->str();
-    size_t len = txt.length();
-    if (len > 65535) {
-        // Hmm, our response is too large. Let's send the first
-        // 64KB and hope for the best.
-        LOG_ERROR(command_logger, COMMAND_SOCKET_RESPONSE_TOOLARGE).arg(len);
+    // Close the connection if we have sent the entire response.
+    connection_pool_.stop(shared_from_this());
+}
+
+void
+Connection::sendHandler(const boost::system::error_code& ec,
+                        size_t bytes_transferred) {
+    if (ec) {
+        // If an error occurred, log this error and stop the connection.
+        if (ec.value() != boost::asio::error::operation_aborted) {
+            LOG_ERROR(command_logger, COMMAND_SOCKET_WRITE_FAIL)
+                .arg(socket_->getNative()).arg(ec.message());
+        }
+
+    } else {
+        // No error. We are in a process of sending a response. Need to
+        // remove the chunk that we have managed to sent with the previous
+        // attempt.
+        response_.erase(0, bytes_transferred);
+
+        LOG_DEBUG(command_logger, DBG_COMMAND, COMMAND_SOCKET_WRITE)
+            .arg(bytes_transferred).arg(response_.size())
+            .arg(socket_->getNative());
 
-        len = 65535;
+        // Check if there is any data left to be sent and sent it.
+        if (!response_.empty()) {
+            doSend();
+            return;
+        }
+
+        // Gracefully shutdown the connection and close the socket if
+        // we have sent the whole response.
+        terminate();
     }
 
+    // All data sent or an error has occurred. Close the connection.
+    connection_pool_.stop(shared_from_this());
+}
+
+void
+Connection::timeoutHandler() {
+    LOG_INFO(command_logger, COMMAND_SOCKET_CONNECTION_TIMEOUT)
+        .arg(socket_->getNative());
+
     try {
-        // Send the data back over socket.
-        socket_->write(txt.c_str(), len);
+        socket_->cancel();
 
     } catch (const std::exception& ex) {
-        // Response transmission failed. Since the response failed, it doesn't
-        // make sense to send any status codes. Let's log it and be done with
-        // it.
-        LOG_ERROR(command_logger, COMMAND_SOCKET_WRITE_FAIL)
-            .arg(len).arg(socket_->getNative()).arg(ex.what());
+        LOG_ERROR(command_logger, COMMAND_SOCKET_CONNECTION_CANCEL_FAIL)
+            .arg(socket_->getNative())
+            .arg(ex.what());
     }
 
-    connection_pool_.stop(shared_from_this());
+    ConstElementPtr rsp = createAnswer(CONTROL_RESULT_ERROR, "Connection over"
+                                       " control channel timed out");
+    response_ = rsp->str();
+    doSend();
 }
 
+
 }
 
 namespace isc {
@@ -244,7 +401,7 @@ public:
     /// @brief Constructor.
     CommandMgrImpl()
         : io_service_(), acceptor_(), socket_(), socket_name_(),
-          connection_pool_() {
+          connection_pool_(), timeout_(DEFAULT_CONNECTION_TIMEOUT) {
     }
 
     /// @brief Opens acceptor service allowing the control clients to connect.
@@ -274,6 +431,9 @@ public:
 
     /// @brief Pool of connections.
     ConnectionPool connection_pool_;
+
+    /// @brief Connection timeout
+    unsigned short timeout_;
 };
 
 void
@@ -333,8 +493,14 @@ CommandMgrImpl::doAccept() {
     acceptor_->asyncAccept(*socket_, [this](const boost::system::error_code& ec) {
         if (!ec) {
             // New connection is arriving. Start asynchronous transmission.
-            ConnectionPtr connection(new Connection(socket_, connection_pool_));
+            ConnectionPtr connection(new Connection(io_service_, socket_,
+                                                    connection_pool_,
+                                                    timeout_));
             connection_pool_.start(connection);
+
+        } else if (ec.value() != boost::asio::error::operation_aborted) {
+            LOG_ERROR(command_logger, COMMAND_SOCKET_ACCEPT_FAIL)
+                .arg(acceptor_->getNative()).arg(ec.message());
         }
 
         // Unless we're stopping the service, start accepting connections again.
@@ -385,5 +551,11 @@ CommandMgr::setIOService(const IOServicePtr& io_service) {
     impl_->io_service_ = io_service;
 }
 
+void
+CommandMgr::setConnectionTimeout(const unsigned short timeout) {
+    impl_->timeout_ = timeout;
+}
+
+
 }; // end of isc::config
 }; // end of isc
diff --git a/src/lib/config/command_mgr.h b/src/lib/config/command_mgr.h
index 95055ac03d..5eb23015fb 100644
--- a/src/lib/config/command_mgr.h
+++ b/src/lib/config/command_mgr.h
@@ -54,6 +54,11 @@ public:
     /// @param io_service Pointer to the IO service.
     void setIOService(const asiolink::IOServicePtr& io_service);
 
+    /// @brief Override default connection timeout.
+    ///
+    /// @param timeout New connection timeout in seconds.
+    void setConnectionTimeout(const unsigned short timeout);
+
     /// @brief Opens control socket with parameters specified in socket_info
     ///
     /// Currently supported types are:
diff --git a/src/lib/config/config_messages.mes b/src/lib/config/config_messages.mes
index 891248013f..4262f64673 100644
--- a/src/lib/config/config_messages.mes
+++ b/src/lib/config/config_messages.mes
@@ -59,26 +59,34 @@ information may be provided by the system as second parameter.
 This is an information message indicating that the command connection has been
 closed by a command control client.
 
+% COMMAND_SOCKET_CONNECTION_CANCEL_FAIL Failed to cancel read operation on socket %1: %2
+This error message is issued to indicate an error to cancel asynchronous read
+of the control command over the control socket. The cancel operation is performed
+when the timeout occurs during communication with a client. The error message
+includes details about the reason for failure.
+
 % COMMAND_SOCKET_CONNECTION_CLOSED Closed socket %1 for existing command connection
 This is an informational message that the socket created for handling
 client's connection is closed. This usually means that the client disconnected,
 but may also mean a timeout.
 
-% COMMAND_SOCKET_CONNECTION_OPENED Opened socket %1 for incoming command connection on socket %2
+% COMMAND_SOCKET_CONNECTION_CLOSE_FAIL Failed to close command connection: %1
+This error message is issued when an error occurred when closing a
+command connection and/or removing it from the connections pool. The
+detailed error is provided as an argument.
+
+% COMMAND_SOCKET_CONNECTION_OPENED Opened socket %1 for incoming command connection
 This is an informational message that a new incoming command connection was
 detected and a dedicated socket was opened for that connection.
 
-% COMMAND_SOCKET_DUP_WARN Failed to duplicate socket for response: %1
-This debug message indicates that the commandReader was unable to duplicate
-the connection socket prior to executing the command. This is most likely a
-system resource issue.  The command should still be processed and the response
-sent, unless the command caused the command channel to be closed (e.g. a
-reconfiguration command).
+% COMMAND_SOCKET_CONNECTION_SHUTDOWN_FAIL Encountered error %1 while trying to gracefully shutdown socket
+This message indicates an error while trying to gracefully shutdown command
+connection. The type of the error is included in the message.
 
-% COMMAND_SOCKET_FAIL_NONBLOCK Failed to set non-blocking mode for socket %1 created for incoming connection on socket %2: %3
-This error message indicates that the server failed to set non-blocking mode
-on just created socket. That socket was created for accepting specific
-incoming connection. Additional information may be provided as third parameter.
+% COMMAND_SOCKET_CONNECTION_TIMEOUT Timeout occurred for connection over socket %1
+This is an informational message that indicates that the timeout has
+occurred for one of the command channel connections. The response
+sent by the server indicates a timeout and is then closed.
 
 % COMMAND_SOCKET_READ Received %1 bytes over command socket %2
 This debug message indicates that specified number of bytes was received
@@ -88,27 +96,10 @@ over command socket identified by specified file descriptor.
 This error message indicates that an error was encountered while
 reading from command socket.
 
-% COMMAND_SOCKET_RESPONSE_TOOLARGE Server's response was larger (%1) than supported 64KB
-This error message indicates that the server received a command and generated
-an answer for it, but that response was larger than supported 64KB. Server
-will attempt to send the first 64KB of the response. Depending on the nature
-of this response, this may indicate a software or configuration error. Future
-Kea versions are expected to have better support for large responses.
-
-% COMMAND_SOCKET_UNIX_CLOSE Command socket closed: UNIX, fd=%1, path=%2
-This informational message indicates that the daemon closed a command
-processing socket. This was a UNIX socket. It was opened with the file
-descriptor and path specified.
-
-% COMMAND_SOCKET_UNIX_OPEN Command socket opened: UNIX, fd=%1, path=%2
-This informational message indicates that the daemon opened a command
-processing socket. This is a UNIX socket. It was opened with the file
-descriptor and path specified.
-
-% COMMAND_SOCKET_WRITE Sent response of %1 bytes over command socket %2
+% COMMAND_SOCKET_WRITE Sent response of %1 bytes (%2 bytes left to send) over command socket %3
 This debug message indicates that the specified number of bytes was sent
 over command socket identifier by the specified file descriptor.
 
-% COMMAND_SOCKET_WRITE_FAIL Error while writing %1 bytes to command socket %2 : %3
+% COMMAND_SOCKET_WRITE_FAIL Error while writing to command socket %1 : %2
 This error message indicates that an error was encountered while
 attempting to send a response to the command socket.
diff --git a/src/lib/testutils/unix_control_client.cc b/src/lib/testutils/unix_control_client.cc
index 8057258b6b..a60a130498 100644
--- a/src/lib/testutils/unix_control_client.cc
+++ b/src/lib/testutils/unix_control_client.cc
@@ -84,18 +84,18 @@ bool UnixControlClient::sendCommand(const std::string& command) {
     return (true);
 }
 
-bool UnixControlClient::getResponse(std::string& response) {
+bool UnixControlClient::getResponse(std::string& response,
+                                    const unsigned int timeout_sec) {
     // Receive response
     char buf[65536];
     memset(buf, 0, sizeof(buf));
-    switch (selectCheck()) {
+    switch (selectCheck(timeout_sec)) {
     case -1: {
         const char* errmsg = strerror(errno);
         ADD_FAILURE() << "getResponse - select failed: " << errmsg;
         return (false);
     }
     case 0:
-        ADD_FAILURE() << "No response data sent";
         return (false);
 
     default:
@@ -120,7 +120,7 @@ bool UnixControlClient::getResponse(std::string& response) {
     return (true);
 }
 
-int UnixControlClient::selectCheck() {
+int UnixControlClient::selectCheck(const unsigned int timeout_sec) {
     int maxfd = 0;
 
     fd_set read_fds;
@@ -131,7 +131,7 @@ int UnixControlClient::selectCheck() {
     maxfd = socket_fd_;
 
     struct timeval select_timeout;
-    select_timeout.tv_sec = 0;
+    select_timeout.tv_sec = static_cast<time_t>(timeout_sec);
     select_timeout.tv_usec = 0;
 
     return (select(maxfd + 1, &read_fds, NULL, NULL, &select_timeout));
diff --git a/src/lib/testutils/unix_control_client.h b/src/lib/testutils/unix_control_client.h
index d76772ec7f..8060d975c8 100644
--- a/src/lib/testutils/unix_control_client.h
+++ b/src/lib/testutils/unix_control_client.h
@@ -44,13 +44,16 @@ public:
     /// @brief Reads the response text from the open Control Channel
     /// @param response variable into which the received response should be
     /// placed.
+    /// @param timeout_sec Timeout for receiving response in seconds.
     /// @return true if data was successfully read from the socket,
     /// false otherwise
-    bool getResponse(std::string& response);
+    bool getResponse(std::string& response, const unsigned int timeout_sec = 0);
 
     /// @brief Uses select to poll the Control Channel for data waiting
+    ///
+    /// @param timeout_sec Select timeout in seconds
     /// @return -1 on error, 0 if no data is available,  1 if data is ready
-    int selectCheck();
+    int selectCheck(const unsigned int timeout_sec);
 
     /// @brief Retains the fd of the open socket
     int socket_fd_;