feat: check for malformed requests

Author: lcsmuller

Diff for: core/error.h

@@ -8,6 +8,8 @@
  *  @{ */
 
 typedef enum CCORDcode {
+    /** failure when creating request's payload */
+    CCORD_MALFORMED_PAYLOAD = -12,
     /** couldn't enqueue worker thread (queue is full) */
     CCORD_FULL_WORKER = -11,
     /** couldn't perform action because resource is unavailable */

Diff for: src/discord-rest.c

@@ -120,6 +120,11 @@ discord_rest_run(struct discord_rest *rest,
         static struct ccord_szbuf blank = { 0 };
         body = ␣
     }
+    else if (body->start && !body->size) {
+        logconf_error(&rest->conf, "(Internal error) Request body couldn't "
+                                   "be formed, please report it.");
+        return CCORD_MALFORMED_PAYLOAD;
+    }
 
     /* build the endpoint string */
     va_start(args, endpoint_fmt);