Set a default MSS when establishing tcb if unset

While the caller to tle_tcp_stream_establish, should provide a complete
connection info to include mss, if it is not provided it will trigger a
divide by zero in tle_tcp_stream_writev. RFCs have defined a default
value for IPv4 and IPv6, which is leveraged if left unspecified.

Signed-off-by: Ben Magistro <[email protected]>
Change-Id: Ic29f4398b22a601eddf2a501e9cc185106457303

diff --git a/lib/libtle_l4p/tcp_rxtx.c b/lib/libtle_l4p/tcp_rxtx.c
index a702177..3d1c550 100644 (file)
--- a/lib/libtle_l4p/tcp_rxtx.c
+++ b/lib/libtle_l4p/tcp_rxtx.c
@@ -2277,7 +2277,17 @@ tcb_establish(struct tle_tcp_stream *s, const struct tle_tcp_conn_info *ci)
        uint32_t mss, tms;
 
        tms = tcp_get_tms(s->s.ctx->cycles_ms_shift);
-       mss = calc_smss(ci->so.mss, &s->tx.dst);
+
+       /* set a default MSS if it is unset (0) */
+       if ((ci->so.mss == 0) && (s->s.type == TLE_V4)) {
+               mss = calc_smss(TCP4_MIN_MSS, &s->tx.dst);
+       }
+       else if ((ci->so.mss == 0) && (s->s.type == TLE_V6)) {
+               mss = calc_smss(TCP6_MIN_MSS, &s->tx.dst);
+       }
+       else {
+               mss = calc_smss(ci->so.mss, &s->tx.dst);
+       }
 
        s->tcb.so = ci->so;
        fill_tcb_snd(&s->tcb, ci->ack, ci->seq, mss,