add request_handler hook

This creates a handler `request_handler' in the same vein as
scheme_handler, download_handler, etc., which is called whenever the
page requests a URI.  (Possible applications include Adblock and SSL
enforcement.)  The handler should get the URI from $1 and print the URI
of the resource that should be loaded instead, or print nothing to allow
the request unmodified.

5 files changed, 37 insertions, 2 deletions

diff --git a/README b/README
index 925392c..ab58ab2 100644
--- a/README
+++ b/README
@@ -313,6 +313,9 @@ file).
   - `data`: The cookie data. Only included for "PUT" requests.
 * `scheme_handler`: handler to execute for each URI navigated to - the
   navigation request will be ignored if handler prints "USED\n"
+* `request_handler`: Executed whenever any request is made.  The handler can
+  print a URI to redirect the request (or `about:blank` to effectively cancel it).
+  If the handler does nothing, the request will continue unchanged.
 * `download_handler`: executed when a download is started. the handler script
   should print a path that the download should be saved to, or print nothing
   to cancel the download.
@@ -507,8 +510,9 @@ access to the following environment variables:
 * `$UZBL_URI`: The URI of the current page.
 * `$UZBL_TITLE`: The current page title.
 
-Handler scripts (`download_handler`, `cookie_handler`, `scheme_handler` and
-`authentication_handler`) are called with special arguments:
+Handler scripts (`download_handler`, `cookie_handler`, `scheme_handler`,
+`request_handler`, and `authentication_handler`) are called with special
+arguments:
 
 * download handler
 
@@ -537,6 +541,10 @@ Handler scripts (`download_handler`, `cookie_handler`, `scheme_handler` and
 
   - `$1 URI` of the page to be navigated to
 
+* request handler
+
+  - `$1 URI` of the resource which is being requested
+
 * authentication handler:
 
   - `$1`: authentication zone unique identifier
diff --git a/examples/config/config b/examples/config/config
index e061e12..92606a2 100644
--- a/examples/config/config
+++ b/examples/config/config
@@ -42,6 +42,7 @@ set scripts_dir      = @data_home/uzbl:@prefix/share/uzbl/examples/data:scripts
 # These handlers can't be moved to the new event system yet as we don't
 # support events that can wait for a response from a script.
 set scheme_handler      = sync_spawn @scripts_dir/scheme.py
+#set request_handler     = sync_spawn @scripts_dir/request.py
 set authentication_handler = sync_spawn @scripts_dir/auth.py
 set download_handler    = sync_spawn @scripts_dir/download.sh
 
diff --git a/src/callbacks.c b/src/callbacks.c
index f939454..23b8d55 100644
--- a/src/callbacks.c
+++ b/src/callbacks.c
@@ -358,7 +358,31 @@ request_starting_cb(WebKitWebView *web_view, WebKitWebFrame *frame, WebKitWebRes
     (void) response;
     (void) user_data;
 
+    const gchar* uri = webkit_network_request_get_uri (request);
+
+    if (uzbl.state.verbose)
+        printf("Request starting -> %s\n", uri);
     send_event (REQUEST_STARTING, NULL, TYPE_STR, webkit_network_request_get_uri(request), NULL);
+
+    if (uzbl.behave.request_handler) {
+        GString *result = g_string_new ("");
+        GArray *a = g_array_new (TRUE, FALSE, sizeof(gchar*));
+        const CommandInfo *c = parse_command_parts(uzbl.behave.request_handler, a);
+
+        if(c) {
+            g_array_append_val(a, uri);
+            run_parsed_command(c, a, result);
+        }
+        g_array_free(a, TRUE);
+
+        if(result->len > 0) {
+            char *p = strchr(result->str, '\n' );
+            if ( p != NULL ) *p = '\0';
+            webkit_network_request_set_uri(request, result->str);
+        }
+
+        g_string_free(result, TRUE);
+    }
 }
 
 void
diff --git a/src/uzbl-core.h b/src/uzbl-core.h
index 35533f7..aa88feb 100644
--- a/src/uzbl-core.h
+++ b/src/uzbl-core.h
@@ -150,6 +150,7 @@ typedef struct {
     /* Handlers */
     gchar*   authentication_handler;
     gchar*   scheme_handler;
+    gchar*   request_handler;
     gchar*   download_handler;
 
     gboolean forward_keys;
diff --git a/src/variables.c b/src/variables.c
index 3bd941b..e414dac 100644
--- a/src/variables.c
+++ b/src/variables.c
@@ -711,6 +711,7 @@ const struct var_name_to_ptr_t {
 
     { "authentication_handler", PTR_V_STR(uzbl.behave.authentication_handler,   1,   set_authentication_handler)},
     { "scheme_handler",         PTR_V_STR(uzbl.behave.scheme_handler,           1,   NULL)},
+    { "request_handler",        PTR_V_STR(uzbl.behave.request_handler,          1,   NULL)},
     { "download_handler",       PTR_V_STR(uzbl.behave.download_handler,         1,   NULL)},
 
     { "fifo_dir",               PTR_V_STR(uzbl.behave.fifo_dir,                 1,   set_fifo_dir)},