BUG/MINOR: mux-h1: Don't delay send if message with c-l was fully sent

In the H1 multiplexer, if a message was fully sent considering the specified
content-length, the MSG_MORE flag must be unset, regardless the upper layer
said. This should avoid a extra latency of 200ms when this happens while the
HTX EOM flag is not set on the message. This may happen for H2/H3 messages
with trailers or if the END_OF_STREAM was not reported yet on H2/H3 side. In
both cases, on H1 side, no more data will be sent (trailers will be
dropped). So we must never delay the send.

This patch should fix the issue #3447. It must be backported to all
supported versions.

diff --git a/src/mux_h1.c b/src/mux_h1.c
index 264cddd280fc833432e7044f6a29ca6a46b04154..854460f902840b906520ca71dc2b5518690f504a 100644 (file)
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -4899,6 +4899,7 @@ static size_t h1_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
 {
        struct h1s *h1s = __sc_mux_strm(sc);
        struct h1c *h1c;
+       struct h1m *h1m;
        size_t total = 0;
 
        if (!h1s)
@@ -4935,6 +4936,7 @@ static size_t h1_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
        if (flags & CO_SFL_STREAMER)
                h1c->flags |= H1C_F_CO_STREAMER;
 
+       h1m = (!(h1c->flags & H1C_F_IS_BACK) ? &h1s->res : &h1s->req);
        while (count) {
                size_t ret = 0;
 
@@ -4948,6 +4950,13 @@ static size_t h1_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
 
                if ((count - ret) > 0)
                        h1c->flags |= H1C_F_CO_MSG_MORE;
+               else {
+                       /* Remove H1C_F_CO_MSG_MORE if a content-length was set and all the payload was sent.
+                        * At worst, it remains trailers from H2/QUIC messages that will be dropped.
+                        */
+                       if ((h1m->flags & H1_MF_CLEN) && !h1m->curr_len)
+                               h1c->flags &= ~H1C_F_CO_MSG_MORE;
+               }
 
                total += ret;
                count -= ret;
@@ -5195,8 +5204,13 @@ static size_t h1_done_ff(struct stconn *sc)
        if (h1m->curr_len)
                h1m->curr_len -= total;
 
-       if (!h1m->curr_len && (h1m->flags & H1_MF_CLEN))
+       if (!h1m->curr_len && (h1m->flags & H1_MF_CLEN)) {
                h1m->state = ((sd->iobuf.flags & IOBUF_FL_EOI) ? H1_MSG_DONE : H1_MSG_TRAILERS);
+               /* Remove H1C_F_CO_MSG_MORE if a content-length was set and all the payload was sent.
+                * At worst, it remains trailers from H2/QUIC messages that will be dropped.
+                */
+               h1c->flags &= ~H1C_F_CO_MSG_MORE;
+       }
        else if (!h1m->curr_len && (h1m->flags & H1_MF_CHNK)) {
                if (h1m->state == H1_MSG_DATA)
                        h1m->state = H1_MSG_CHUNK_CRLF;