uhttpd: add support for adding arbitrary headers via handler scripts

Signed-off-by: Felix Fietkau <nbd@nbd.name>

client.c

@@ -45,8 +45,10 @@ const char * const http_methods[] = {
 void uh_http_header(struct client *cl, int code, const char *summary)
 {
 	struct http_request *r = &cl->request;
+	struct blob_attr *cur;
 	const char *enc = "Transfer-Encoding: chunked\r\n";
 	const char *conn;
+	int rem;
 
 	cl->http_code = code;
 
@@ -64,6 +66,10 @@ void uh_http_header(struct client *cl, int code, const char *summary)
 
 	if (!r->connection_close)
 		ustream_printf(cl->us, "Keep-Alive: timeout=%d\r\n", conf.http_keepalive);
+
+	blobmsg_for_each_attr(cur, cl->hdr_response.head, rem)
+		ustream_printf(cl->us, "%s: %s\r\n", blobmsg_name(cur),
+			       blobmsg_get_string(cur));
 }
 
 static void uh_connection_close(struct client *cl)
@@ -114,6 +120,7 @@ void uh_request_done(struct client *cl)
 {
 	uh_chunk_eof(cl);
 	uh_dispatch_done(cl);
+	blob_buf_init(&cl->hdr_response, 0);
 	memset(&cl->dispatch, 0, sizeof(cl->dispatch));
 
 	if (!conf.http_keepalive || cl->request.connection_close)
@@ -530,6 +537,7 @@ static void client_close(struct client *cl)
 	close(cl->sfd.fd.fd);
 	list_del(&cl->list);
 	blob_buf_free(&cl->hdr);
+	blob_buf_free(&cl->hdr_response);
 	free(cl);
 
 	uh_unblock_listeners();

file.c

@@ -863,6 +863,7 @@ void uh_handle_request(struct client *cl)
 	char *url = blobmsg_data(blob_data(cl->hdr.head));
 	char *error_handler;
 
+	blob_buf_init(&cl->hdr_response, 0);
 	url = uh_handle_alias(url);
 
 	uh_handler_run(cl, &url, false);

handler.c

@@ -102,6 +102,24 @@ handle_set_uri(struct json_script_ctx *ctx, struct blob_attr *data)
 	json_script_abort(ctx);
 }
 
+static void
+handle_add_header(struct json_script_ctx *ctx, struct blob_attr *data)
+{
+	struct client *cl = cur_client;
+	static struct blobmsg_policy policy[2] = {
+		 { .type = BLOBMSG_TYPE_STRING },
+		 { .type = BLOBMSG_TYPE_STRING },
+	};
+	struct blob_attr *tb[2];
+
+	blobmsg_parse_array(policy, ARRAY_SIZE(tb), tb, blobmsg_data(data), blobmsg_data_len(data));
+	if (!tb[0] || !tb[1])
+		return;
+
+	blobmsg_add_string(&cl->hdr_response, blobmsg_get_string(tb[0]),
+			   blobmsg_get_string(tb[1]));
+}
+
 static void
 handle_command(struct json_script_ctx *ctx, const char *name,
 	       struct blob_attr *data, struct blob_attr *vars)
@@ -111,7 +129,8 @@ handle_command(struct json_script_ctx *ctx, const char *name,
 		void (*func)(struct json_script_ctx *ctx, struct blob_attr *data);
 	} cmds[] = {
 		{ "redirect", handle_redirect },
-		{ "rewrite", handle_set_uri }
+		{ "rewrite", handle_set_uri },
+		{ "add-header", handle_add_header },
 	};
 	int i;
 

uhttpd.h

@@ -258,6 +258,7 @@ struct client {
 	struct uh_addr srv_addr, peer_addr;
 
 	struct blob_buf hdr;
+	struct blob_buf hdr_response;
 	struct dispatch dispatch;
 };