[src/trunk]: src/sys/net/npf npf_state_tcp: add an assert; fix some comments ...

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/9b009b7ef2ac
branches:  trunk
changeset: 779622:9b009b7ef2ac
user:      rmind <rmind%NetBSD.org@localhost>
date:      Tue Jun 05 22:46:54 2012 +0000

description:
npf_state_tcp: add an assert; fix some comments while here.

diffstat:

 sys/net/npf/npf_state_tcp.c |  19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diffs (82 lines):

diff -r 8438c652382d -r 9b009b7ef2ac sys/net/npf/npf_state_tcp.c
--- a/sys/net/npf/npf_state_tcp.c       Tue Jun 05 22:28:11 2012 +0000
+++ b/sys/net/npf/npf_state_tcp.c       Tue Jun 05 22:46:54 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: npf_state_tcp.c,v 1.5 2012/05/30 21:38:03 rmind Exp $  */
+/*     $NetBSD: npf_state_tcp.c,v 1.6 2012/06/05 22:46:54 rmind Exp $  */
 
 /*-
  * Copyright (c) 2010-2011 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: npf_state_tcp.c,v 1.5 2012/05/30 21:38:03 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: npf_state_tcp.c,v 1.6 2012/06/05 22:46:54 rmind Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -54,7 +54,7 @@
  * NPF TCP states.  Note: these states are different from the TCP FSM
  * states of RFC 793.  The packet filter is a man-in-the-middle.
  */
-#define NPF_TCPS_OK            (-1)
+#define        NPF_TCPS_OK             (-1)
 #define        NPF_TCPS_CLOSED         0
 #define        NPF_TCPS_SYN_SENT       1
 #define        NPF_TCPS_SIMSYN_SENT    2
@@ -330,8 +330,9 @@
         */
        if (__predict_false(fstate->nst_maxwin == 0)) {
                /*
-                * Should be first SYN or re-transmission of SYN.  State of
-                * other side will get set with a SYN-ACK reply (see below).
+                * Normally, it should be the first SYN or a re-transmission
+                * of SYN.  The state of the other side will get set with a
+                * SYN-ACK reply (see below).
                 */
                fstate->nst_end = end;
                fstate->nst_maxend = end;
@@ -370,6 +371,7 @@
                            wscale : 0;
                }
        }
+
        if ((tcpfl & TH_ACK) == 0) {
                /* Pretend that an ACK was sent. */
                ack = tstate->nst_end;
@@ -384,7 +386,7 @@
        }
 #if 0
        /* Strict in-order sequence for RST packets. */
-       if (((tcpfl & TH_RST) != 0) && (fstate->nst_end - seq) > 1) {
+       if ((tcpfl & TH_RST) != 0 && (fstate->nst_end - seq) > 1) {
                return false;
        }
 #endif
@@ -404,7 +406,7 @@
        }
 
        /*
-        * Boundaries for valid acknowledgments (III, IV) - on predicted
+        * Boundaries for valid acknowledgments (III, IV) - one predicted
         * window up or down, since packets may be fragmented.
         */
        ackskew = tstate->nst_end - ack;
@@ -420,6 +422,7 @@
         * Negative ackskew might be due to fragmented packets.  Since the
         * total length of the packet is unknown - bump the boundary.
         */
+
        if (ackskew < 0) {
                tstate->nst_end = ack;
        }
@@ -444,6 +447,8 @@
        const int tcpfl = th->th_flags, state = nst->nst_state;
        int nstate;
 
+       KASSERT(mutex_owned(&nst->nst_lock));
+
        /* Look for a transition to a new state. */
        if (__predict_true((tcpfl & TH_RST) == 0)) {
                const int flagcase = npf_tcpfl2case(tcpfl);