print-bootp.c: enhancement to print END, PAD options

[Kevin Steves <stevesk () pobox com>]

The following patch does the following:

0) use TTEST/TCHECK macros vs. snapend comparisons
1) when -vvv display PAD and END options
   (multiple PAD options are summarized)
2) change a trunc string from bootp to rfc1048 because I think that is
   what is intended (matches trunc label)

It may make sense to split these into separate diffs and I would
be glad to do that.

Example output:

11:34:18.663078 IP (tos 0x0, ttl 128, id 1362, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 
255.255.255.255.67: [udp sum ok]
 BOOTP/DHCP, Request from 00:01:6c:eb:20:b9, length 300, xid 0x599292b3, Flags [ none ] (0x0000)
          Client-Ethernet-Address 00:01:6c:eb:20:b9
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            NOAUTO Option 116, length 1: Y
            Client-ID Option 61, length 7: ether 00:01:6c:eb:20:b9
            Hostname Option 12, length 10: "ksteves-xp"
            Vendor-Class Option 60, length 8: "MSFT 5.0"
            Parameter-Request Option 55, length 11: 
              Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
              Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
              Static-Route, Option 249, Vendor-Option
            END Option 255, length 0
            PAD Option 0, length 0, occurs 9

Index: print-bootp.c
===================================================================
RCS file: /tcpdump/master/tcpdump/print-bootp.c,v
retrieving revision 1.81
diff -u -r1.81 print-bootp.c
--- print-bootp.c       13 Feb 2006 18:59:29 -0000      1.81
+++ print-bootp.c       10 Jan 2007 20:52:22 -0000
@@ -374,11 +374,11 @@
        bp += sizeof(int32_t);
 
        /* Loop while we there is a tag left in the buffer */
-       while (bp + 1 < snapend) {
+       while (TTEST2(*bp, 1)) {
                tag = *bp++;
-               if (tag == TAG_PAD)
+               if (tag == TAG_PAD && vflag < 3)
                        continue;
-               if (tag == TAG_END)
+               if (tag == TAG_END && vflag < 3)
                        return;
                if (tag == TAG_EXTENDED_OPTION) {
                        TCHECK2(*(bp + 1), 2);
@@ -392,17 +392,29 @@
                        cp = tok2str(tag2str, "?T%u", tag);
                c = *cp++;
 
-               /* Get the length; check for truncation */
-               if (bp + 1 >= snapend) {
-                       fputs(tstr, stdout);
-                       return;
+               if (tag == TAG_PAD || tag == TAG_END)
+                       len = 0;
+               else {
+                       /* Get the length; check for truncation */
+                       TCHECK2(*bp, 1);
+                       len = *bp++;
                }
-               len = *bp++;
 
-               printf("\n\t    %s Option %u, length %u: ", cp, tag, len);
+               printf("\n\t    %s Option %u, length %u%s", cp, tag, len,
+                   len > 0 ? ": " : "");
+
+               if (tag == TAG_PAD && vflag > 2) {
+                       u_int ntag = 1;
+                       while (TTEST2(*bp, 1) && *bp == TAG_PAD) {
+                               bp++;
+                               ntag++;
+                       }
+                       if (ntag > 1)
+                               printf(", occurs %u", ntag);
+               }
 
-               if (bp + len >= snapend) {
-                       printf("[|bootp %u]", len);
+               if (!TTEST2(*bp, len)) {
+                       printf("[|rfc1048 %u]", len);
                        return;
                }
 
-
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