fix to keep alive segments

SCCS-vsn: sys/netinet/tcp_timer.c 4.17

diff --git a/usr/src/sys/netinet/tcp_timer.c b/usr/src/sys/netinet/tcp_timer.c
index ce8c3db..f038b4e 100644 (file)
--- a/usr/src/sys/netinet/tcp_timer.c
+++ b/usr/src/sys/netinet/tcp_timer.c
@@ -1,4 +1,4 @@
-/* tcp_timer.c 4.16 82/03/15 */
+/* tcp_timer.c 4.17 82/03/19 */

 
 #include "../h/param.h"
 #include "../h/systm.h"
 
 #include "../h/param.h"
 #include "../h/systm.h"


@@ -167,10 +167,20 @@ printf("rexmt set to %d\n", tp->t_timer[TCPT_REXMT]);
                        tcp_drop(tp, ETIMEDOUT);
                        return;
                }
                        tcp_drop(tp, ETIMEDOUT);
                        return;
                }

-               if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE)
+               if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) {
+                       /*
+                        * Saying tp->rcv_nxt-1 lies about what
+                        * we have received, and by the protocol spec
+                        * requires the correspondent TCP to respond.
+                        * Saying tp->snd_una-1 causes the transmitted
+                        * byte to lie outside the receive window; this
+                        * is important because we don't necessarily
+                        * have a byte in the window to send (consider
+                        * a one-way stream!)
+                        */

                        tcp_respond(tp,
                        tcp_respond(tp,

-                           tp->t_template, tp->rcv_nxt, tp->snd_una-1, 0);
-               else
+                           tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0);
+               } else

                        tp->t_idle = 0;
                tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
                return;
                        tp->t_idle = 0;
                tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
                return;