[libgrss] src: Fix binding between mode and parameters in publisher

[Philip Withnall <pwithnall src gnome org>]

commit 79842ad8f207238346e3af985cf2e93c6319bf10
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Dec 21 16:51:33 2016 +0000

    src: Fix binding between mode and parameters in publisher
    
    Previously, the code assumed that the correct parameters were provided
    for each mode, but that’s not necessarily the case. If incorrect
    parameters were provided (specifically, if the ones pertaining to the
    given mode were missing), some NULL pointer dereferences would happen
    and hence the code would crash.
    
    Fix that by checking for the parameters and returning error 400 if they
    are not present.
    
    Coverity IDs: 1388546, 1388547
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776115

 src/feeds-publisher.c |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/src/feeds-publisher.c b/src/feeds-publisher.c
index 772d73b..2c919c6 100644
--- a/src/feeds-publisher.c
+++ b/src/feeds-publisher.c
@@ -840,12 +840,17 @@ handle_incoming_requests_cb (SoupServer *server, SoupMessage *msg, const char *p
                        }
                }
                else if (strcmp (mode, "unsubscribe") == 0) {
-                       client = search_subscriber_by_topic_and_callback (pub, topic, callback);
-                       if (client != NULL)
-                               client->status = REMOTE_UNSUBSCRIBING;
+                       if (callback == NULL) {
+                               soup_message_set_status (msg, 400);
+                       }
+                       else {
+                               client = search_subscriber_by_topic_and_callback (pub, topic, callback);
+                               if (client != NULL)
+                                       client->status = REMOTE_UNSUBSCRIBING;
+                       }
                }
 
-               if (client != NULL) {
+               if (client != NULL && verify != NULL) {
                        verify_msg = verification_message_for_client (client);
 
                        if (strcmp (verify, "sync") == 0) {
@@ -859,6 +864,9 @@ handle_incoming_requests_cb (SoupServer *server, SoupMessage *msg, const char *p
                                soup_message_set_status (msg, 202);
                        }
                }
+               else if (client != NULL) {
+                       soup_message_set_status (msg, 400);
+               }
        }
 
        g_strfreev (contents);