Handle redirect on response status for apache

Author: joelwurtz

src/mod_redirectionio.c

@@ -13,9 +13,13 @@ static char errbuf[1024];
 
 static void redirectionio_register_hooks(apr_pool_t *p);
 
+static void ap_headers_insert_output_filter(request_rec *r);
+
 static int redirectionio_redirect_handler(request_rec *r);
 static int redirectionio_log_handler(request_rec *r);
 
+static apr_status_t redirectionio_filter_match_on_response(ap_filter_t *f, apr_bucket_brigade *b);
+
 static apr_status_t redirectionio_create_connection(redirectionio_connection *conn, redirectionio_config *config, apr_pool_t *pool);
 static redirectionio_connection* redirectionio_acquire_connection(redirectionio_config *config, apr_pool_t *pool);
 static apr_status_t redirectionio_release_connection(redirectionio_connection *conn, redirectionio_config *config, apr_pool_t *pool);
@@ -54,6 +58,29 @@ module AP_MODULE_DECLARE_DATA redirectionio_module = {
 static void redirectionio_register_hooks(apr_pool_t *p) {
     ap_hook_handler(redirectionio_redirect_handler, NULL, NULL, APR_HOOK_FIRST);
     ap_hook_log_transaction(redirectionio_log_handler, NULL, NULL, APR_HOOK_MIDDLE);
+
+    ap_hook_insert_filter(ap_headers_insert_output_filter, NULL, NULL, APR_HOOK_LAST);
+    ap_hook_insert_error_filter(ap_headers_insert_output_filter, NULL, NULL, APR_HOOK_LAST);
+    ap_register_output_filter("redirectionio_redirect_filter", redirectionio_filter_match_on_response, NULL, AP_FTYPE_CONTENT_SET);
+}
+
+static void ap_headers_insert_output_filter(request_rec *r) {
+    redirectionio_config    *config = (redirectionio_config*) ap_get_module_config(r->per_dir_config, &redirectionio_module);
+    redirectionio_context   *ctx = ap_get_module_config(r->request_config, &redirectionio_module);
+
+    if (config->enable != 1) {
+        return;
+    }
+
+    if (ctx == NULL || ctx->status == 0 || ctx->match_on_response_status == 0 || ctx->is_redirected) {
+        return;
+    }
+
+    if (r->status != ctx->match_on_response_status) {
+        return;
+    }
+
+    ap_add_output_filter("redirectionio_redirect_filter", ctx, r, r->connection);
 }
 
 static int redirectionio_redirect_handler(request_rec *r) {
@@ -72,6 +99,10 @@ static int redirectionio_redirect_handler(request_rec *r) {
         return DECLINED;
     }
 
+    context->status = 0;
+    context->match_on_response_status = 0;
+    context->is_redirected = 0;
+
     ap_set_module_config(r->request_config, &redirectionio_module, context);
     redirectionio_connection* conn = redirectionio_acquire_connection(config, r->pool);
 
@@ -86,10 +117,14 @@ static int redirectionio_redirect_handler(request_rec *r) {
         return DECLINED;
     }
 
-    // No match
+    redirectionio_release_connection(conn, config, r->pool);
+
+    // No match here
     if (context->status == 0) {
-        redirectionio_release_connection(conn, config, r->pool);
+        return DECLINED;
+    }
 
+    if (context->match_on_response_status > 0) {
         return DECLINED;
     }
 
@@ -98,12 +133,27 @@ static int redirectionio_redirect_handler(request_rec *r) {
     }
 
     r->status = context->status;
-
-    redirectionio_release_connection(conn, config, r->pool);
+    context->is_redirected = 1;
 
     return context->status;
 }
 
+static apr_status_t redirectionio_filter_match_on_response(ap_filter_t *f, apr_bucket_brigade *bb) {
+    redirectionio_context   *ctx = (redirectionio_context *)f->ctx;
+
+    if (ctx->status != 410) {
+        apr_table_setn(f->r->headers_out, "Location", ctx->target);
+    }
+
+    f->r->status = ctx->status;
+    ctx->is_redirected = 1;
+
+    /* remove ourselves from the filter chain */
+    ap_remove_output_filter(f);
+
+    return ap_pass_brigade(f->next, bb);
+}
+
 static int redirectionio_log_handler(request_rec *r) {
     redirectionio_config *config = (redirectionio_config*) ap_get_module_config(r->per_dir_config, &redirectionio_module);
 

src/mod_redirectionio.h

@@ -40,9 +40,11 @@ typedef struct {
 } redirectionio_connection;
 
 typedef struct {
-    char                        *matched_rule_id;
-    char                        *target;
-    int                         status;
+    char    *matched_rule_id;
+    char    *target;
+    int     status;
+    int     match_on_response_status;
+    int     is_redirected;
 } redirectionio_context;
 
 #endif

src/redirectionio_protocol.c

@@ -5,7 +5,7 @@
 
 static char errbuf[1024];
 
-const char COMMAND_MATCH_NAME[] = "MATCH";
+const char COMMAND_MATCH_NAME[] = "MATCH_WITH_RESPONSE";
 const char COMMAND_MATCH_QUERY[] = "{ \"project_id\": \"%s\", \"request_uri\": \"%s\", \"host\": \"%s\" }";
 const char COMMAND_LOG_NAME[] = "LOG";
 const char COMMAND_LOG_QUERY[] = "{ \"project_id\": \"%s\", \"request_uri\": \"%s\", \"host\": \"%s\", \"rule_id\": \"%s\", \"target\": \"%s\", \"status_code\": %d, \"user_agent\": \"%s\", \"referer\": \"%s\" }";
@@ -48,6 +48,7 @@ apr_status_t redirectionio_protocol_match(redirectionio_connection *conn, redire
     }
 
     cJSON *status = cJSON_GetObjectItem(result, "status_code");
+    cJSON *match_on_response_status = cJSON_GetObjectItem(result, "match_on_response_status");
     cJSON *location = cJSON_GetObjectItem(result, "location");
     cJSON *matched_rule = cJSON_GetObjectItem(result, "matched_rule");
     cJSON *rule_id = NULL;
@@ -59,13 +60,19 @@ apr_status_t redirectionio_protocol_match(redirectionio_connection *conn, redire
     if (matched_rule == NULL || matched_rule->type == cJSON_NULL) {
         ctx->matched_rule_id = "";
         ctx->status = 0;
+        ctx->match_on_response_status = 0;
 
         return APR_SUCCESS;
     }
 
     ctx->matched_rule_id = rule_id->valuestring;
     ctx->target = location->valuestring;
     ctx->status = status->valueint;
+    ctx->match_on_response_status = 0;
+
+    if (match_on_response_status != NULL && match_on_response_status->type != cJSON_NULL) {
+        ctx->match_on_response_status = match_on_response_status->valueint;
+    }
 
     return APR_SUCCESS;
 }