BUG/MEDIUM: mux-fcgi: Handle cases where the HTX EOM block cannot be inserted

During the HTTP response parsing, if there is not enough space in the channel's
buffer, it is possible to fail to add the HTX EOM block while all data in the
rxbuf were consumed. As for the h1 mux, we must notify the conn-stream the
buffer is full to have a chance to add the HTX EOM block later. In this case, we
must also be carefull to not report a server abort by setting too early the
CS_FL_EOS flag on the conn-stream.

To do so, the FCGI_SF_APPEND_EOM flag must be set on the FCGI stream to know the
HTX EOM block is missing.

This patch must be backported to 2.1.

diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index c502670df87724e2b58b7048146aad8ccba1721a..f8ee0b7e4b3e01061c5853670e94fa830ebfd6ca 100644 (file)
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -146,6 +146,7 @@ enum fcgi_strm_st {
 
 /* Other flags */
 #define FCGI_SF_HAVE_I_TLR     0x00010000 /* Set during input process to know the trailers were processed */
+#define FCGI_SF_APPEND_EOM     0x00020000 /* Send EOM to the HTX buffer */
 
 /* FCGI stream descriptor */
 struct fcgi_strm {
@@ -3178,6 +3179,14 @@ static size_t fcgi_strm_parse_data(struct fcgi_strm *fstrm, struct h1m *h1m, str
        }
        *ofs += ret;
   end:
+       if (h1m->state == H1_MSG_DONE) {
+               fstrm->flags &= ~FCGI_SF_APPEND_EOM;
+               TRACE_STATE("end of message", FCGI_EV_RSP_DATA|FCGI_EV_RSP_EOM, fstrm->fconn->conn);
+       }
+       else if (h1m->state == H1_MSG_DATA && (h1m->flags & H1_MF_XFER_LEN) && h1m->curr_len == 0) {
+               fstrm->flags |= FCGI_SF_APPEND_EOM;
+               TRACE_STATE("add append_eom", FCGI_EV_RSP_DATA, fstrm->fconn->conn);
+       }
        TRACE_LEAVE(FCGI_EV_RSP_DATA|FCGI_EV_RSP_BODY, fstrm->fconn->conn, fstrm,, (size_t[]){ret});
        return ret;
 }
@@ -3209,10 +3218,14 @@ static size_t fcgi_strm_add_eom(struct fcgi_strm *fstrm, struct h1m *h1m, struct
                                size_t max)
 {
        TRACE_ENTER(FCGI_EV_RSP_DATA, fstrm->fconn->conn, fstrm,, (size_t[]){max});
-       if (max < sizeof(struct htx_blk) + 1 || !htx_add_endof(htx, HTX_BLK_EOM))
+       if (max < sizeof(struct htx_blk) + 1 || !htx_add_endof(htx, HTX_BLK_EOM)) {
+               fstrm->flags |= FCGI_SF_APPEND_EOM;
+               TRACE_STATE("leaving on append_eom", FCGI_EV_RSP_DATA, fstrm->fconn->conn);
                return 0;
+       }
 
        h1m->state = H1_MSG_DONE;
+       fstrm->flags &= ~FCGI_SF_APPEND_EOM;
        TRACE_STATE("end of response", FCGI_EV_RSP_DATA|FCGI_EV_RSP_EOM, fstrm->fconn->conn, fstrm);
        TRACE_LEAVE(FCGI_EV_RSP_DATA, fstrm->fconn->conn, fstrm);
        return (sizeof(struct htx_blk) + 1);
@@ -3780,7 +3793,7 @@ static size_t fcgi_rcv_buf(struct conn_stream *cs, struct buffer *buf, size_t co
        else
                TRACE_STATE("fstrm rxbuf not allocated", FCGI_EV_STRM_RECV|FCGI_EV_FSTRM_BLK, fconn->conn, fstrm);
 
-       if (b_data(&fstrm->rxbuf))
+       if (b_data(&fstrm->rxbuf) || (fstrm->flags & FCGI_SF_APPEND_EOM))
                cs->flags |= (CS_FL_RCV_MORE | CS_FL_WANT_ROOM);
        else {
                cs->flags &= ~(CS_FL_RCV_MORE | CS_FL_WANT_ROOM);