add support for AS-PIC cookies

[tcpdump] / print-chdlc.c

diff --git a/print-chdlc.c b/print-chdlc.c
index 65437d1c7245a37781c18e5800f3733c41380cba..ea1a197af81328e87d608c561049583dfed71859 100644 (file)
--- a/print-chdlc.c
+++ b/print-chdlc.c
@@ -21,7 +21,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-chdlc.c,v 1.32.2.2 2005-04-09 09:42:25 hannes Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-chdlc.c,v 1.32.2.7 2005-04-27 14:35:56 hannes Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -112,6 +112,9 @@ chdlc_if_print(const struct pcap_pkthdr *h, register const u_char *p)
        return (CHDLC_HDRLEN);
 }
 
+/*
+ * The fixed-length portion of a SLARP packet.
+ */
 struct cisco_slarp {
        u_int8_t code[4];
 #define SLARP_REQUEST  0
@@ -126,12 +129,12 @@ struct cisco_slarp {
                        u_int8_t myseq[4];
                        u_int8_t yourseq[4];
                        u_int8_t rel[2];
-                        u_int8_t time[0];
                } keep;
        } un;
 };
 
-#define SLARP_LEN      18
+#define SLARP_MIN_LEN  14
+#define SLARP_MAX_LEN  18
 
 static void
 chdlc_slarp_print(const u_char *cp, u_int length)
@@ -140,16 +143,23 @@ chdlc_slarp_print(const u_char *cp, u_int length)
         u_int sec,min,hrs,days;
 
         printf("SLARP (length: %u), ",length);
-       if (length < SLARP_LEN)
+       if (length < SLARP_MIN_LEN)
                goto trunc;
 
        slarp = (const struct cisco_slarp *)cp;
-       TCHECK(*slarp);
+       TCHECK2(*slarp, SLARP_MIN_LEN);
        switch (EXTRACT_32BITS(&slarp->code)) {
        case SLARP_REQUEST:
                printf("request");
-                /* ok we do not know it - but lets at least dump it */
-                print_unknown_data(cp+4,"\n\t",length-4);
+               /*
+                * At least according to William "Chops" Westfield's
+                * message in
+                *
+                *      http://www.nethelp.no/net/cisco-hdlc.txt
+                *
+                * the address and mask aren't used in requests -
+                * they're just zero.
+                */
                break;
        case SLARP_REPLY:
                printf("reply %s/%s",
@@ -162,8 +172,11 @@ chdlc_slarp_print(const u_char *cp, u_int length)
                        EXTRACT_32BITS(&slarp->un.keep.yourseq),
                        EXTRACT_16BITS(&slarp->un.keep.rel));
 
-                if (length >= SLARP_LEN) { /* uptime-stamp is optional */
-                        sec = EXTRACT_32BITS(&slarp->un.keep.time) / 1000;
+                if (length >= SLARP_MAX_LEN) { /* uptime-stamp is optional */
+                        cp += SLARP_MIN_LEN;
+                        if (!TTEST2(*cp, 4))
+                                goto trunc;
+                        sec = EXTRACT_32BITS(cp) / 1000;
                         min = sec / 60; sec -= min * 60;
                         hrs = min / 60; min -= hrs * 60;
                         days = hrs / 24; hrs -= days * 24;
@@ -177,8 +190,8 @@ chdlc_slarp_print(const u_char *cp, u_int length)
                break;
        }
 
-       if (SLARP_LEN < length && vflag)
-               printf(", (trailing junk: %d bytes)", length - SLARP_LEN);
+       if (SLARP_MAX_LEN < length && vflag)
+               printf(", (trailing junk: %d bytes)", length - SLARP_MAX_LEN);
         if (vflag > 1)
             print_unknown_data(cp+4,"\n\t",length-4);
        return;