BUG/MINOR: h3: fix TRAILERS encoding

HTTP/3 trailers encoding was never working as intended. It's because
h3_trailers_to_htx() manipulate a newly allocated buffer instead of the
already existing channel one. Thus, HTX message handled by the stream
was incomplete as it lacked trailers and EOM.

Fix this by reusing the already allocated channel buffer in
h3_trailers_to_htx().

This bug was detected by simulating TRAILERS emission which generate
CL--- state due to missing request side termination signal. Its impact
is deemed as minimal as trailers are pretty infrequent for now in
HTTP/3.

This must be backported up to 2.7.

diff --git a/src/h3.c b/src/h3.c
index 793388df0f8455270a8c16b014fc2d446006315d..a6953c33627df313fd0e504fc8a2b0ec10824ebe 100644 (file)
--- a/src/h3.c
+++ b/src/h3.c
@@ -846,8 +846,8 @@ static ssize_t h3_trailers_to_htx(struct qcs *qcs, const struct buffer *buf,
 {
        struct h3s *h3s = qcs->ctx;
        struct h3c *h3c = h3s->h3c;
-       struct buffer htx_buf = BUF_NULL;
        struct buffer *tmp = get_trash_chunk();
+       struct buffer *appbuf = NULL;
        struct htx *htx = NULL;
        struct htx_sl *sl;
        struct http_hdr list[global.tune.max_http_hdr];
@@ -868,14 +868,14 @@ static ssize_t h3_trailers_to_htx(struct qcs *qcs, const struct buffer *buf,
                goto out;
        }
 
-       if (!qcs_get_buf(qcs, &htx_buf)) {
+       if (!(appbuf = qcs_get_buf(qcs, &qcs->rx.app_buf))) {
                TRACE_ERROR("HTX buffer alloc failure", H3_EV_RX_FRAME|H3_EV_RX_HDR, qcs->qcc->conn, qcs);
                h3c->err = H3_INTERNAL_ERROR;
                len = -1;
                goto out;
        }
-       BUG_ON(!b_size(&htx_buf)); /* TODO */
-       htx = htx_from_buf(&htx_buf);
+       BUG_ON(!b_size(appbuf)); /* TODO */
+       htx = htx_from_buf(appbuf);
 
        if (!h3s->data_len) {
                /* Notify that no body is present. This can only happens if
@@ -972,13 +972,10 @@ static ssize_t h3_trailers_to_htx(struct qcs *qcs, const struct buffer *buf,
        if (fin)
                htx->flags |= HTX_FL_EOM;
 
-       htx_to_buf(htx, &htx_buf);
-       htx = NULL;
-
  out:
        /* HTX may be non NULL if error before previous htx_to_buf(). */
-       if (htx)
-               htx_to_buf(htx, &htx_buf);
+       if (appbuf)
+               htx_to_buf(htx, appbuf);
 
        TRACE_LEAVE(H3_EV_RX_FRAME|H3_EV_RX_HDR, qcs->qcc->conn, qcs);
        return len;