diff options
| author | Lawrence Teo <lteo@cvs.openbsd.org> | 2014-01-11 04:40:46 +0000 |
|---|---|---|
| committer | Lawrence Teo <lteo@cvs.openbsd.org> | 2014-01-11 04:40:46 +0000 |
| commit | c6333c11ef5db00078e7f93f8f6278d16a576753 (patch) | |
| tree | 4c884f0c1b91fd21f2abfb313d6bc7ea8cab89b2 | |
| parent | 17a396dd4e2d5d4a1387a44bc71c59d327388ef4 (diff) | |
Let tcpdump detect bad ICMP checksums with the -v flag.
Tested on amd64, i386, loongson, and macppc.
OK florian@
| -rw-r--r-- | usr.sbin/tcpdump/print-icmp.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/usr.sbin/tcpdump/print-icmp.c b/usr.sbin/tcpdump/print-icmp.c index a554c0a434f..fcb51f4478a 100644 --- a/usr.sbin/tcpdump/print-icmp.c +++ b/usr.sbin/tcpdump/print-icmp.c @@ -1,4 +1,4 @@ -/* $OpenBSD: print-icmp.c,v 1.21 2014/01/11 04:35:52 lteo Exp $ */ +/* $OpenBSD: print-icmp.c,v 1.22 2014/01/11 04:40:45 lteo Exp $ */ /* * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994, 1995, 1996 @@ -373,7 +373,17 @@ icmp_print(const u_char *bp, u_int length, const u_char *bp2) str = tok2str(icmp2str, "type-#%u", dp->icmp_type); break; } - (void)printf("icmp: %s", str); + (void)printf("icmp: %s", str); + if (vflag) { + u_int16_t sum; + if (TTEST2(dp->icmp_type, length)) { + sum = in_cksum((const u_short *)dp, length, 0); + if (sum != 0) + (void)printf(" [bad icmp cksum %x!]", sum); + else + (void)printf(" [icmp cksum ok]"); + } + } if (vflag > 1 && !ICMP_INFOTYPE(dp->icmp_type) && TTEST(dp->icmp_ip)) { (void)printf(" for "); |