[Patch] Add fragment summary info

[guyharris]

Converted from SourceForge issue 1257271, submitted by rayharris

This patch adds the fragment summary information to the
end of fragmented packets and adds DF and rsvd flag
information to the end of all packets. An example would be:

(frag 1282:1126@1480+) (DF, RES)

This information is suppressed by the -q flag.

The college I teach at has tcpdump labs based on this
information being present. We just switched to Fedora
Core 4 and noticed this info was now missing from
tcpdump output. It was easier to patch tcpdump than to
rewrite the labs.

Ray

[guyharris]

Submitted by guy_harris

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user_id=541179

See the thread starting at

http://www.tcpdump.org/lists/workers/2003/04/msg00334.html

for the discussion that led up to the change. You might want to raise this issue
on tcpdump-workers.

[infrastation]

The suggested change:

*** tcpdump-3.9.3/print-ip.c    2005-08-11 22:41:36.000000000 -0400
--- tcpdump-3.9.3-frag/print-ip.c   2005-08-11 23:17:22.000000000 -0400
***************
*** 347,353 ****
--- 347,355 ----
  #ifndef IP_DF
  #define IP_DF 0x4000
  #endif /* IP_DF */
+ #ifndef IP_RES
  #define IP_RES 0x8000
+ #endif /* IP_RES */

  static struct tok ip_frag_values[] = {
          { IP_MF,        "+" },
***************
*** 689,694 ****
--- 691,726 ----
            (void)printf(" ip-proto-%d", ipds->ip->ip_p);
        } 
    }
+ 
+         /*
+          * For fragmented datagrams, print id:size@offset. On all
+          * but the last fragment add a "+".
+          */
+ 
+   if (qflag) return; /* if quiet, don't print frag info */
+ 
+         if(ipds->off & 0x3fff) { /* MF is set or offset is non-zero */
+             (void)printf(" (frag %u:%u@%d",
+                 EXTRACT_16BITS(&ipds->ip->ip_id),
+                 EXTRACT_16BITS(&ipds->ip->ip_len),
+                 (ipds->off & 0x1fff) * 8);
+             if(ipds->off & IP_MF) { /* MF flag is set */
+                 (void)printf("+");
+             }
+             (void)printf(")");
+         }
+ 
+   /* For all packets, note if the DF or rsvd flag is set */
+ 
+         if(ipds->off & (IP_DF | IP_RES) == (IP_DF | IP_RES) ) {
+             /* rsvd and DF flag is set */
+             (void)printf(" (DF, RES)");
+         } else if(ipds->off & IP_DF) { /* DF flag is set */
+             (void)printf(" (DF)");
+         } else if(ipds->off * IP_RES) { /* rsvd flag is set */
+             (void)printf(" (RES)");
+         }
+ 
  }

  void