From: Amaury Denoyelle <adenoyelle@haproxy.com>
Date: Tue, 10 Jun 2025 15:45:27 +0000 (+0200)
Subject: MINOR: h3: convert HTTP/3 response into HTX for backend side support
X-Git-Tag: v3.3-dev2~42
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f79effa30665edef5e7617797936e794b8309d13;p=thirdparty%2Fhaproxy.git

MINOR: h3: convert HTTP/3 response into HTX for backend side support

Implement basic support for HTTP/3 request response transcoding into
HTX. This is done via a new dedicated function h3_resp_headers_to_htx().
A valid HTX status-line is allocated and stored. Status code is
hardcoded to 200 for now.

Following patches will be added to remove hardcoded status value and
also handle response headers provided by the server.
---

diff --git a/src/h3.c b/src/h3.c
index 8373edc14..d1c798cd0 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -1087,6 +1087,81 @@ static ssize_t h3_req_headers_to_htx(struct qcs *qcs, const struct buffer *buf,
 	return len;
 }
 
+/* Parse from <buf> a H3 response HEADERS frame of length <len>. Data is
+ * transcoded into HTX buffer of <qcs> stream. <fin> must be set if this is the
+ * last data to transfer for this stream.
+ *
+ * Returns the number of consumed bytes or a negative error code.
+ */
+static ssize_t h3_resp_headers_to_htx(struct qcs *qcs, const struct buffer *buf,
+                                      uint64_t len, char fin)
+{
+	struct h3s *h3s = qcs->ctx;
+	struct buffer *appbuf = NULL;
+	struct htx *htx = NULL;
+	struct htx_sl *sl;
+	unsigned int flags = HTX_SL_F_NONE;
+	struct ist status = ist("200");
+
+	/* RFC 9114 4.1.2. Malformed Requests and Responses
+	 *
+	 * A malformed request or response is one that is an otherwise valid
+	 * sequence of frames but is invalid due to:
+	 * - the presence of prohibited fields or pseudo-header fields,
+	 * - the absence of mandatory pseudo-header fields,
+	 * - invalid values for pseudo-header fields,
+	 * - pseudo-header fields after fields,
+	 * - an invalid sequence of HTTP messages,
+	 * - the inclusion of uppercase field names, or
+	 * - the inclusion of invalid characters in field names or values.
+	 *
+	 * [...]
+	 *
+	 * Intermediaries that process HTTP requests or responses (i.e., any
+	 * intermediary not acting as a tunnel) MUST NOT forward a malformed
+	 * request or response. Malformed requests or responses that are
+	 * detected MUST be treated as a stream error of type H3_MESSAGE_ERROR.
+	 */
+
+	TRACE_ENTER(H3_EV_RX_FRAME|H3_EV_RX_HDR, qcs->qcc->conn, qcs);
+
+	appbuf = qcc_get_stream_rxbuf(qcs);
+	BUG_ON(!appbuf || b_data(appbuf)); /* TODO */
+	BUG_ON(!b_size(appbuf)); /* TODO */
+	htx = htx_from_buf(appbuf);
+
+	flags |= HTX_SL_F_VER_11;
+	flags |= HTX_SL_F_XFER_LEN;
+
+	sl = htx_add_stline(htx, HTX_BLK_RES_SL, flags, ist("HTTP/3.0"), status, ist(""));
+	if (!sl) {
+		TRACE_ERROR("cannot allocate HTX start-line", H3_EV_RX_FRAME|H3_EV_RX_HDR, qcs->qcc->conn, qcs);
+		h3s->err = H3_ERR_MESSAGE_ERROR;
+		len = -1;
+		goto out;
+	}
+
+	if (fin)
+		sl->flags |= HTX_SL_F_BODYLESS;
+
+	sl->info.res.status = 200;
+
+	if (!htx_add_endof(htx, HTX_BLK_EOH)) {
+		len = -1;
+		goto out;
+	}
+
+	if (fin)
+		htx->flags |= HTX_FL_EOM;
+
+ out:
+	if (appbuf)
+		htx_to_buf(htx, appbuf);
+
+	TRACE_LEAVE(H3_EV_RX_FRAME|H3_EV_RX_HDR, qcs->qcc->conn, qcs);
+	return len;
+}
+
 /* Parse from buffer <buf> a H3 HEADERS frame of length <len> used as trailers.
  * Data are copied in a local HTX buffer and transfer to the stream connector
  * layer. <fin> must be set if this is the last data to transfer from this
@@ -1554,7 +1629,9 @@ static ssize_t h3_rcv_buf(struct qcs *qcs, struct buffer *b, int fin)
 			break;
 		case H3_FT_HEADERS:
 			if (h3s->st_req == H3S_ST_REQ_BEFORE) {
-				ret = h3_req_headers_to_htx(qcs, b, flen, last_stream_frame);
+				ret = !conn_is_back(qcs->qcc->conn) ?
+				  h3_req_headers_to_htx(qcs, b, flen, last_stream_frame) :
+				  h3_resp_headers_to_htx(qcs, b, flen, last_stream_frame);
 				h3s->st_req = H3S_ST_REQ_HEADERS;
 			}
 			else {
@@ -2392,9 +2469,6 @@ static size_t h3_snd_buf(struct qcs *qcs, struct buffer *buf, size_t count)
 		btype = htx_get_blk_type(blk);
 		bsize = htx_get_blksz(blk);
 
-		/* Not implemented : QUIC on backend side */
-		BUG_ON(btype == HTX_BLK_REQ_SL);
-
 		switch (btype) {
 		case HTX_BLK_REQ_SL:
 			ret = h3_req_headers_send(qcs, htx);