Get rid of zero-length arrays in structures - they're not standard C89

and not all C compilers support them.

The minimum length of a SLARP packet is 14 bytes, not 18 bytes.  SLARP
requests don't have any data, apparently.

diff --git a/print-chdlc.c b/print-chdlc.c
index 295dab3e6b21daf0f1f386aab55dd3ef954d3982..8d272620dfc5bcf0179edf16a5ca8bd3be8a4d35 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 1.32.2.3 2005-04-10 06:42:54 hannes Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-chdlc.c,v 1.32.2.4 2005-04-19 08:07:03 guy 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 +129,11 @@ 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_LEN      14
 
 static void
 chdlc_slarp_print(const u_char *cp, u_int length)
@@ -144,12 +146,19 @@ chdlc_slarp_print(const u_char *cp, u_int length)
                goto trunc;
 
        slarp = (const struct cisco_slarp *)cp;
-       TCHECK(*slarp);
+       TCHECK2(*slarp, SLARP_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",
@@ -163,9 +172,10 @@ chdlc_slarp_print(const u_char *cp, u_int length)
                        EXTRACT_16BITS(&slarp->un.keep.rel));
 
                 if (length >= SLARP_LEN) { /* uptime-stamp is optional */
-                        if (!TTEST2(slarp->un.keep.time, 4))
+                        cp += SLARP_LEN;
+                        if (!TTEST2(*cp, 4))
                                 goto trunc;
-                        sec = EXTRACT_32BITS(&slarp->un.keep.time) / 1000;
+                        sec = EXTRACT_32BITS(cp) / 1000;
                         min = sec / 60; sec -= min * 60;
                         hrs = min / 60; min -= hrs * 60;
                         days = hrs / 24; hrs -= days * 24;