Changeset f398c61

Timestamp:

04/21/17 14:40:32 (4 years ago)

Author:

Shane Alcock <salcock@…>

Branches:

cachetimestamps, develop, dpdk-ndag, etsilive, master, ndag_format, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance

Children:

633339d, b606855, d47ca18, e9c089a

Parents:

ed3a238

Message:

Libpacketdump now recognises truncated IPv6 headers

This should fix #48, as well as avoid displaying bogus IPv6
header fields when the captured packet is too short to actually
contain useful values for them.

File:

• libpacketdump/eth_34525.c (modified) (1 diff)

libpacketdump/eth_34525.c

@@ -38 +38 @@
 {
         libtrace_ip6_t *ip = (libtrace_ip6_t*)packet;
-        
         uint32_t tmp = ntohl(*(uint32_t*)ip);
 
-        printf(" IPv6: Version %u\n", (tmp >> 28) & 0x000000f);
-        printf(" IPv6: Class %u\n", (tmp >> 20) & 0x000000ff);
-        printf(" IPv6: Flow Label %u\n", tmp & 0x000fffff);
-        printf(" IPv6: Payload Length %u\n", ntohs(ip->plen));
-        printf(" IPv6: Next Header %u\n", ip->nxt);
-        printf(" IPv6: Hop Limit %u\n", ip->hlim);
+        int truncated = 0;
+        char ipstr[INET6_ADDRSTRLEN];
 
+        do {
+                if (len < 4) {
+                        truncated = 1;
+                        break;
+                }
 
-        char ipstr[INET6_ADDRSTRLEN];                             
-        inet_ntop(AF_INET6, &(ip->ip_src), ipstr, INET6_ADDRSTRLEN);
+                printf(" IPv6: Version %u\n", (tmp >> 28) & 0x000000f);
+                printf(" IPv6: Class %u\n", (tmp >> 20) & 0x000000ff);
+                printf(" IPv6: Flow Label %u\n", tmp & 0x000fffff);
 
-        printf(" IPv6: Source IP %s\n", ipstr);
-        inet_ntop(AF_INET6, &(ip->ip_dst), ipstr, INET6_ADDRSTRLEN);
-        printf(" IPv6: Destination IP %s\n", ipstr);
+                if (len < 6) {
+                        truncated = 1;
+                        break;
+                }
+                printf(" IPv6: Payload Length %u\n", ntohs(ip->plen));
+
+                if (len < 7) {
+                        truncated = 1;
+                        break;
+                }
+                printf(" IPv6: Next Header %u\n", ip->nxt);
+                if (len < 8) {
+                        truncated = 1;
+                        break;
+                }
+                printf(" IPv6: Hop Limit %u\n", ip->hlim);
+
+                if (len < 24) {
+                        truncated = 1;
+                        break;
+                }
+
+                inet_ntop(AF_INET6, &(ip->ip_src), ipstr, INET6_ADDRSTRLEN);
+                printf(" IPv6: Source IP %s\n", ipstr);
+
+                if (len < 40) {
+                        truncated = 1;
+                        break;
+                }
+
+                inet_ntop(AF_INET6, &(ip->ip_dst), ipstr, INET6_ADDRSTRLEN);
+                printf(" IPv6: Destination IP %s\n", ipstr);
+        } while (0);
+
+        if (truncated) {
+                printf(" IPv6: [Truncated]\n");
+                return;
+        }
 
         decode_next(packet+sizeof(libtrace_ip6_t),len-sizeof(libtrace_ip6_t),"ip",ip->nxt);