From: Tomas Krizek <tomas.krizek@nic.cz>
Date: Thu, 1 Apr 2021 15:04:10 +0000 (+0200)
Subject: daemon/http: improve handling of stream errors
X-Git-Tag: v5.3.2~9^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2cdec753ca46248cea97eb65d33e812ea68f919c;p=thirdparty%2Fknot-resolver.git

daemon/http: improve handling of stream errors

The on_frame_recv() callback ins't guaranteed to be called by nghttp2.
This can happen e.g. in a case when nghttp2 issues a PROTOCOL_ERROR
RST_STREAM frame. Previously, it would leave the connection in a
stream-processing state, making it completely useless.

While this guarantees a cleanup will be called eventually, some streams
may still get ignored due to the order of various callbacks and data
processing procedures. Still, it's better than the previous
implementation.
---

diff --git a/daemon/http.c b/daemon/http.c
index f72465f65..5782941e6 100644
--- a/daemon/http.c
+++ b/daemon/http.c
@@ -243,6 +243,15 @@ static void refuse_stream(nghttp2_session *h2, int32_t stream_id)
 		h2, NGHTTP2_FLAG_NONE, stream_id, NGHTTP2_REFUSED_STREAM);
 }
 
+/* Return the http ctx into a pristine state in which no stream is being processed. */
+static void http_cleanup_stream(struct http_ctx *ctx)
+{
+	ctx->incomplete_stream = -1;
+	ctx->current_method = HTTP_METHOD_NONE;
+	free(ctx->uri_path);
+	ctx->uri_path = NULL;
+}
+
 /*
  * Save stream id from first header's frame.
  *
@@ -388,10 +397,7 @@ static int on_frame_recv_callback(nghttp2_session *h2, const nghttp2_frame *fram
 				refuse_stream(h2, stream_id);
 			}
 		}
-		ctx->incomplete_stream = -1;
-		ctx->current_method = HTTP_METHOD_NONE;
-		free(ctx->uri_path);
-		ctx->uri_path = NULL;
+		http_cleanup_stream(ctx);
 
 		len = ctx->buf_pos - sizeof(uint16_t);
 		if (len <= 0 || len > KNOT_WIRE_MAX_PKTSIZE) {
@@ -431,6 +437,12 @@ static int on_stream_close_callback(nghttp2_session *h2, int32_t stream_id,
 				    uint32_t error_code, void *user_data)
 {
 	struct http_data *data;
+	struct http_ctx *ctx = (struct http_ctx *)user_data;
+
+	/* Ensure connection state is cleaned up in case the stream gets
+	 * unexpectedly closed, e.g. by PROTOCOL_ERROR issued from nghttp2. */
+	if (ctx->incomplete_stream == stream_id)
+		http_cleanup_stream(ctx);
 
 	data = nghttp2_session_get_stream_user_data(h2, stream_id);
 	if (data)