BUG/MEDIUM: spoe/mux-spop: Introduce an NOOP action to deal with empty ACK

In the SPOP protocol, ACK frame with empty payload are allowed. However, in
that case, because only the payload is transferred, there is no data to
return to the SPOE applet. Only the end of input is reported. Thus the
applet is never woken up. It means that the SPOE filter will be blocked
during the processing timeout and will finally return an error.

To workaournd this issue, a NOOP action is introduced with the value 0. It
is only an internal action for now. It does not exist in the SPOP
protocol. When an ACK frame with an empy payload is received, this noop
action is transferred to the SPOE applet, instead of nothing. Thanks to this
trick, the applet is properly notified. This works because unknown actions
are ignored by the SPOE filter.

This patch must be backported to 3.1.

(cherry picked from commit 851e52b551f80f319b0de1817fc91b7f3949fc67)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

diff --git a/include/haproxy/spoe-t.h b/include/haproxy/spoe-t.h
index e2db8a1..2b91d14 100644 (file)
--- a/include/haproxy/spoe-t.h
+++ b/include/haproxy/spoe-t.h
@@ -52,6 +52,7 @@
 
 /* All supported SPOP actions */
 enum spoe_action_type {
+       SPOP_ACT_T_NOOP = 0, /* internal action for ampty ACK */
        SPOP_ACT_T_SET_VAR = 1,
        SPOP_ACT_T_UNSET_VAR,
        SPOP_ACT_TYPES,

diff --git a/src/mux_spop.c b/src/mux_spop.c
index 251efab..7edc3b7 100644 (file)
--- a/src/mux_spop.c
+++ b/src/mux_spop.c
@@ -1884,8 +1884,16 @@ static int spop_conn_handle_ack(struct spop_conn *spop_conn, struct spop_strm *s
        }
 
        flen = spop_conn->dfl;
-       if (!flen)
+       if (!flen) {
+               if (!b_room(rxbuf)) {
+                       spop_conn->flags |= SPOP_CF_DEM_SFULL;
+                       TRACE_STATE("spop_strm rxbuf is full", SPOP_EV_RX_FRAME|SPOP_EV_RX_ACK|SPOP_EV_SPOP_STRM_BLK, spop_conn->conn, spop_strm);
+                       goto fail;
+               }
+               b_putchr(rxbuf, SPOP_ACT_T_NOOP);
+               sent = 1;
                goto end;
+       }
 
        // TODO: For now we know all data were received
        /* if (flen > b_data(&h2c->dbuf)) { */
@@ -1914,12 +1922,13 @@ static int spop_conn_handle_ack(struct spop_conn *spop_conn, struct spop_strm *s
        /*      /\* The upper layer has already closed *\/ */
 
        /* } */
+
+  end:
        if (spop_strm->state == SPOP_SS_OPEN)
                spop_strm->state = SPOP_SS_HREM;
        else
                spop_strm_close(spop_strm);
 
-  end:
        spop_strm->flags |= SPOP_SF_ACK_RCVD;
        TRACE_PROTO("SPOP AGENT ACK frame rcvd", SPOP_EV_RX_FRAME|SPOP_EV_RX_ACK, spop_conn->conn, spop_strm, 0, (size_t[]){sent});
        spop_conn->state = SPOP_CS_FRAME_H;