mod_include: Add the onerror attribute to the include element, allowing

an URL to be specified to include on error.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1037335 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 66 insertions, 13 deletions

diff --git a/CHANGES b/CHANGES
index 1c736e6c2c..23cc717545 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,10 @@ Changes with Apache 2.3.9
      Fix a denial of service attack against mod_reqtimeout.
      [Stefan Fritsch]
 
+  *) mod_include: Add the onerror attribute to the include element,
+     allowing an URL to be specified to include on error. [Graham
+     Leggett]
+
   *) mod_cache_disk: mod_disk_cache renamed to mod_cache_disk, to be
      consistent with the naming of other modules. [Graham Leggett]
 
diff --git a/docs/manual/mod/mod_include.xml b/docs/manual/mod/mod_include.xml
index 9c479f4460..f843718a77 100644
--- a/docs/manual/mod/mod_include.xml
+++ b/docs/manual/mod/mod_include.xml
@@ -331,9 +331,10 @@
       scripts are invoked as normal using the complete URL given in
       the command, including any query string.</p>
 
-      <p>An attribute defines the location of the document; the
-      inclusion is done for each attribute given to the include
-      command. The valid attributes are:</p>
+      <p>An attribute defines the location of the document, and may
+      appear more than once in an include element; an inclusion is
+      done for each attribute given to the include command in turn.
+      The valid attributes are:</p>
 
       <dl>
       <dt><code>file</code></dt>
@@ -359,11 +360,11 @@
       <p>If the specified URL is a CGI program, the program will be
       executed and its output inserted in place of the directive in the
       parsed file. You may include a query string in a CGI url:</p>
- 
+
       <example>
         &lt;!--#include virtual="/cgi-bin/example.cgi?argument=value" --&gt;
       </example>
- 
+
       <p><code>include virtual</code> should be used in preference
       to <code>exec cgi</code> to include the output of CGI programs
       into an HTML document.</p>
@@ -376,6 +377,26 @@
       requests.</p>
 
       </dd>
+
+      <dt><code>onerror</code></dt>
+      <dd><p>The value is a (%-encoded) URL-path which is shown should a
+      previous attempt to include a file or virtual attribute failed.
+      To be effective, this attribute must be specified after the
+      file or virtual attributes being covered. If the attempt to
+      include the onerror path fails, or if onerror is not specified, the
+      default error message will be included.</p>
+
+      <example>
+        # Simple example<br />
+        &lt;!--#include virtual="/not-exist.html" onerror="/error.html" --&gt;
+      </example>
+
+      <example>
+        # Dedicated onerror paths<br />
+        &lt;!--#include virtual="/path-a.html" onerror="/error-a.html" virtual="/path-b.html" onerror="/error-b.html" --&gt;
+      </example>
+
+      </dd>
       </dl>
     </section> <!-- /include -->
 
diff --git a/docs/manual/new_features_2_4.xml b/docs/manual/new_features_2_4.xml
index b4a9aa74b6..94539bd5d9 100644
--- a/docs/manual/new_features_2_4.xml
+++ b/docs/manual/new_features_2_4.xml
@@ -107,6 +107,13 @@
       <dt><module>mod_allowmethods</module></dt>
       <dd>New module to restrict certain HTTP methods without interfering with
       authentication or authorization.</dd>
+
+      <dt><module>mod_include</module></dt>
+
+      <dd>Support for the 'onerror' attribute within an 'include' element,
+      allowing an error document to be served on error instead of the default
+      error string.</dd>
+
     </dl>
   </section>
 
diff --git a/modules/filters/mod_include.c b/modules/filters/mod_include.c
index 45ea141116..c8d90fd055 100644
--- a/modules/filters/mod_include.c
+++ b/modules/filters/mod_include.c
@@ -1648,12 +1648,19 @@ static int find_file(request_rec *r, const char *directive, const char *tag,
 }
 
 /*
- * <!--#include virtual|file="..." [virtual|file="..."] ... -->
+ * <!--#include virtual|file="..." [onerror|virtual|file="..."] ... -->
+ *
+ * Output each file/virtual in turn until one of them returns an error.
+ * On error, ignore all further file/virtual attributes until we reach
+ * an onerror attribute, where we make an attempt to serve the onerror
+ * virtual url. If onerror fails, or no onerror is present, the default
+ * error string is inserted into the stream.
  */
 static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
                                    apr_bucket_brigade *bb)
 {
     request_rec *r = f->r;
+    char *last_error;
 
     if (!ctx->argc) {
         ap_log_rerror(APLOG_MARK,
@@ -1672,6 +1679,7 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
         return APR_SUCCESS;
     }
 
+    last_error = NULL;
     while (1) {
         char *tag     = NULL;
         char *tag_val = NULL;
@@ -1684,7 +1692,8 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
             break;
         }
 
-        if (strcmp(tag, "virtual") && strcmp(tag, "file")) {
+        if (strcmp(tag, "virtual") && strcmp(tag, "file") && strcmp(tag,
+                "onerror")) {
             ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "unknown parameter "
                           "\"%s\" to tag include in %s", tag, r->filename);
             SSI_CREATE_ERROR_BUCKET(ctx, f, bb);
@@ -1709,7 +1718,8 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
                 rr = ap_sub_req_lookup_file(newpath, r, f->next);
             }
         }
-        else {
+        else if ((tag[0] == 'v' && !last_error)
+                || (tag[0] == 'o' && last_error)) {
             if (r->kept_body) {
                 rr = ap_sub_req_method_uri(r->method, parsed_string, r, f->next);
             }
@@ -1717,6 +1727,9 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
                 rr = ap_sub_req_lookup_uri(parsed_string, r, f->next);
             }
         }
+        else {
+            continue;
+        }
 
         if (!error_fmt && rr->status != HTTP_OK) {
             error_fmt = "unable to include \"%s\" in parsed file %s";
@@ -1743,8 +1756,15 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
 
         if (error_fmt) {
             ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, error_fmt, tag_val,
-                          r->filename);
-            SSI_CREATE_ERROR_BUCKET(ctx, f, bb);
+                    r->filename);
+            if (last_error) {
+                /* onerror threw an error, give up completely */
+                break;
+            }
+            last_error = error_fmt;
+        }
+        else {
+            last_error = NULL;
         }
 
         /* Do *not* destroy the subrequest here; it may have allocated
@@ -1752,9 +1772,10 @@ static apr_status_t handle_include(include_ctx_t *ctx, ap_filter_t *f,
          * r->pool, so that pool must survive as long as this request.
          * Yes, this is a memory leak. */
 
-        if (error_fmt) {
-            break;
-        }
+    }
+
+    if (last_error) {
+        SSI_CREATE_ERROR_BUCKET(ctx, f, bb);
     }
 
     return APR_SUCCESS;