res_ari.c: Prefer exact handler match over wildcard

Given the following request path and 2 handler paths...
Request: /channels/externalMedia
Handler: /channels/{channelId}      "wildcard"
Handler: /channels/externalmedia    "non-wildcard"

...if /channels/externalMedia was registered as a handler after
/channels/{channelId} as shown above, the request would automatically
match the wildcard handler and attempt to parse "externalMedia" into
the channelId variable which isn't what was intended.  It'd work
if the non-wildard entry was defined in rest-api/api-docs/channels.json
before the wildcard entry but that makes the json files
order-dependent which isn't a good thing.

To combat this issue, the search loop saves any wildcard match but
continues looking for exact matches at the same level.  If it finds
one, it's used.  If it hasn't found an exact match at the end of
the current level, the wildcard is used.  Regardless, after
searching the current level, the wildcard is cleared so it won't
accidentally match for a different object or a higher level.

BTW, it's currently not possible for more than 1 wildcard entry
to be defined for a level.  For instance, there couldn't be:
Handler: /channels/{channelId}
Handler: /channels/{channelName}
We wouldn't know which one to match.

Change-Id: I574aa3cbe4249c92c30f74b9b40e750e9002f925

diff --git a/res/res_ari.c b/res/res_ari.c
index ee4a00ed7df49cd267a34b93bf9d6447a6ece3b7..682d3e931beba33c8fded440b25708c119832dd5 100644 (file)
--- a/res/res_ari.c
+++ b/res/res_ari.c
@@ -495,6 +495,7 @@ void ast_ari_invoke(struct ast_tcptls_session_instance *ser,
 {
        RAII_VAR(struct stasis_rest_handlers *, root, NULL, ao2_cleanup);
        struct stasis_rest_handlers *handler;
+       struct stasis_rest_handlers *wildcard_handler = NULL;
        RAII_VAR(struct ast_variable *, path_vars, NULL, ast_variables_destroy);
        char *path = ast_strdupa(uri);
        char *path_segment;
@@ -503,37 +504,49 @@ void ast_ari_invoke(struct ast_tcptls_session_instance *ser,
        root = handler = get_root_handler();
        ast_assert(root != NULL);
 
+       ast_debug(3, "Finding handler for %s\n", path);
+
        while ((path_segment = strsep(&path, "/")) && (strlen(path_segment) > 0)) {
                struct stasis_rest_handlers *found_handler = NULL;
                int i;
 
                ast_uri_decode(path_segment, ast_uri_http_legacy);
-               ast_debug(3, "Finding handler for %s\n", path_segment);
+               ast_debug(3, "  Finding handler for %s\n", path_segment);
 
                for (i = 0; found_handler == NULL && i < handler->num_children; ++i) {
                        struct stasis_rest_handlers *child = handler->children[i];
 
-                       ast_debug(3, "  Checking %s\n", child->path_segment);
                        if (child->is_wildcard) {
                                /* Record the path variable */
                                struct ast_variable *path_var = ast_variable_new(child->path_segment, path_segment, __FILE__);
                                path_var->next = path_vars;
                                path_vars = path_var;
-                               found_handler = child;
+                               wildcard_handler = child;
+                               ast_debug(3, "        Checking %s %s:  Matched wildcard.\n", handler->path_segment, child->path_segment);
+
                        } else if (strcmp(child->path_segment, path_segment) == 0) {
                                found_handler = child;
+                               ast_debug(3, "        Checking %s %s:  Explicit match with %s\n", handler->path_segment, child->path_segment, path_segment);
+                       } else {
+                               ast_debug(3, "        Checking %s %s:  Didn't match %s\n", handler->path_segment, child->path_segment, path_segment);
                        }
                }
 
+               if (!found_handler && wildcard_handler) {
+                       ast_debug(3, "  No explicit handler found for %s.  Using wildcard %s.\n",
+                               path_segment, wildcard_handler->path_segment);
+                       found_handler = wildcard_handler;
+                       wildcard_handler = NULL;
+               }
+
                if (found_handler == NULL) {
                        /* resource not found */
-                       ast_debug(3, "  Handler not found\n");
+                       ast_debug(3, "  Handler not found for %s\n", path_segment);
                        ast_ari_response_error(
                                response, 404, "Not Found",
                                "Resource not found");
                        return;
                } else {
-                       ast_debug(3, "  Got it!\n");
                        handler = found_handler;
                }
        }