[src/trunk]: src/sys/netinet Several changes in syn_cache_respond:

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

details:   https://anonhg.NetBSD.org/src/rev/e5fa14eba0cf
branches:  trunk
changeset: 321618:e5fa14eba0cf
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Mar 28 14:43:55 2018 +0000

description:
Several changes in syn_cache_respond:

 * Replace idiotic diagnostic check by KASSERT. max_linkhdr+tlen<=MCLBYTES
   is a widespread assumption.

 * Improve initialization of 'tp'.

 * Put panics in dead branches.

 * Merge two switches.

diffstat:

 sys/netinet/tcp_input.c |  51 ++++++++++++++++++------------------------------
 1 files changed, 19 insertions(+), 32 deletions(-)

diffs (126 lines):

diff -r 1403e1809c17 -r e5fa14eba0cf sys/netinet/tcp_input.c
--- a/sys/netinet/tcp_input.c   Wed Mar 28 14:30:42 2018 +0000
+++ b/sys/netinet/tcp_input.c   Wed Mar 28 14:43:55 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_input.c,v 1.392 2018/03/28 14:30:42 maxv Exp $     */
+/*     $NetBSD: tcp_input.c,v 1.393 2018/03/28 14:43:55 maxv Exp $     */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.392 2018/03/28 14:30:42 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.393 2018/03/28 14:43:55 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -4370,7 +4370,7 @@
 #ifdef INET6
        struct ip6_hdr *ip6 = NULL;
 #endif
-       struct tcpcb *tp = NULL;
+       struct tcpcb *tp;
        struct tcphdr *th;
        struct mbuf *m;
        u_int hlen;
@@ -4393,17 +4393,13 @@
                return EAFNOSUPPORT;
        }
 
-       /* worst case scanario, since we don't know the option size yet  */
+       /* Worst case scanario, since we don't know the option size yet. */
        tlen = hlen + sizeof(struct tcphdr) + MAX_TCPOPTLEN;
+       KASSERT(max_linkhdr + tlen <= MCLBYTES);
 
        /*
         * Create the IP+TCP header from scratch.
         */
-#ifdef DIAGNOSTIC
-       if (max_linkhdr + tlen > MCLBYTES)
-               return ENOBUFS;
-#endif  
-
        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m && (max_linkhdr + tlen) > MHLEN) {
                MCLGET(m, M_DONTWAIT);
@@ -4416,12 +4412,12 @@
                return ENOBUFS;
        MCLAIM(m, &tcp_tx_mowner);
 
+       tp = sc->sc_tp;
+
        /* Fixup the mbuf. */
        m->m_data += max_linkhdr;
-       if (sc->sc_tp)
-               tp = sc->sc_tp;
        m_reset_rcvif(m);
-       memset(mtod(m, u_char *), 0, tlen);
+       memset(mtod(m, void *), 0, tlen);
 
        switch (sc->sc_src.sa.sa_family) {
        case AF_INET:
@@ -4448,7 +4444,7 @@
                break;
 #endif
        default:
-               return ENOBUFS;
+               panic("%s: impossible (1)", __func__);
        }
 
        th->th_seq = htonl(sc->sc_iss);
@@ -4590,34 +4586,26 @@
        }
 
 
-       /* Compute the packet's checksum. */
+       /*
+        * Compute the packet's checksum.
+        *
+        * Fill in some straggling IP bits.  Note the stack expects
+        * ip_len to be in host order, for convenience.
+        */
        switch (sc->sc_src.sa.sa_family) {
        case AF_INET:
                ip->ip_len = htons(tlen - hlen);
                th->th_sum = 0;
                th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
+               ip->ip_len = htons(tlen);
+               ip->ip_ttl = ip_defttl;
+               /* XXX tos? */
                break;
 #ifdef INET6
        case AF_INET6:
                ip6->ip6_plen = htons(tlen - hlen);
                th->th_sum = 0;
                th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
-               break;
-#endif
-       }
-
-       /*
-        * Fill in some straggling IP bits.  Note the stack expects
-        * ip_len to be in host order, for convenience.
-        */
-       switch (sc->sc_src.sa.sa_family) {
-       case AF_INET:
-               ip->ip_len = htons(tlen);
-               ip->ip_ttl = ip_defttl;
-               /* XXX tos? */
-               break;
-#ifdef INET6
-       case AF_INET6:
                ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
                ip6->ip6_vfc |= IPV6_VERSION;
                ip6->ip6_plen = htons(tlen - hlen);
@@ -4647,8 +4635,7 @@
                break;
 #endif
        default:
-               error = EAFNOSUPPORT;
-               break;
+               panic("%s: impossible (2)", __func__);
        }
 
        return error;