[#129] Added -DEVHTP_SORT_CALLBACKS option for sorting callbacks

Added a compile-time flag -DEVHTP_SORT_CALLBACKS which will auto-sort
globs and non-regex callbacks to search from longest to shortest.

This is optional since we do not want to potentially mess up any code
currently running in production that does this sort of thing manually
(ie ordering code).

CMakeLists.txt

@@ -123,6 +123,10 @@ if(EVHTP_THR_SHARED_PIPE)
     target_compile_definitions(evhtp PUBLIC EVTHR_SHARED_PIPE)
 endif()
 
+if (EVHTP_SORT_CALLBACKS)
+    target_compile_definitions(evhtp PUBLIC EVHTP_SORT_CALLBACKS)
+endif()
+
 if(has_c99)
     target_compile_definitions(evhtp PUBLIC EVHTP_HAS_C99)
 endif()

cmake/options.cmake

@@ -11,6 +11,9 @@ option (EVHTP_DISABLE_REGEX "Disable regex support"        OFF)
 # -DEVHTP_DEBUG=ON
 option (EVHTP_DEBUG         "Enable verbose debug logging"     OFF)
 
+# -DEVHTP_SORT_CALLBACKS=ON
+option (EVHTP_SORT_CALLBACKS "Sort callback strings by length" OFF)
+
 # can be overwritten by new set_alloc functions
 set(EVHTP_ALLOCATOR CACHE STRING "Allocator library")
 set_property(CACHE EVHTP_ALLOCATOR PROPERTY STRINGS "jemalloc;tcmalloc")

evhtp.c

@@ -4290,10 +4290,58 @@ evhtp_callback_free(evhtp_callback_t * callback)
 int
 evhtp_callbacks_add_callback(evhtp_callbacks_t * cbs, evhtp_callback_t * cb)
 {
+#ifdef EVHTP_SORT_CALLBACKS
+    evhtp_callback_t * callback;
+    size_t             cblen;
+
+    if (TAILQ_FIRST(cbs) == NULL) {
+        TAILQ_INSERT_TAIL(cbs, cb, next);
+
+        return 0;
+    }
+
+    switch (cb->type) {
+        case evhtp_callback_type_hash:
+            cblen = cb->len;
+            break;
+        case evhtp_callback_type_glob:
+            cblen = strlen(cb->val.glob);
+            break;
+        case evhtp_callback_type_regex:
+            cblen = 0;
+            break;
+        default:
+            cblen = 0;
+            break;
+    }
+
+    TAILQ_FOREACH(callback, cbs, next) {
+        size_t len = 0;
+
+        switch (callback->type) {
+            case evhtp_callback_type_hash:
+                len = callback->len;
+                break;
+            case evhtp_callback_type_regex:
+                len = 0;
+                break;
+            case evhtp_callback_type_glob:
+                len = strlen(callback->val.glob);
+                break;
+        }
+
+        if (cblen >= len) {
+            TAILQ_INSERT_BEFORE(callback, cb, next);
+
+            return 0;
+        }
+    }
+#endif
+
     TAILQ_INSERT_TAIL(cbs, cb, next);
 
     return 0;
-}
+} /* evhtp_callbacks_add_callback */
 
 static int
 htp__set_hook_(evhtp_hooks_t ** hooks, evhtp_hook_type type, evhtp_hook cb, void * arg)