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CVE-2016-7931/Add bounds and length checks.
[tcpdump] / print-mpls.c
diff --git a/print-mpls.c b/print-mpls.c
index c6b0814ffefcac2f5c848584849cc9f70748b161..f6ee434e96d5a8cca81e6a92363a9e6333075e5a 100644 (file)
--- a/print-mpls.c
+++ b/print-mpls.c
@@ -26,24 +26,16 @@
  * SUCH DAMAGE.
  */
 
  * SUCH DAMAGE.
  */
 
-#ifndef lint
-static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-mpls.c,v 1.14 2005-07-05 09:38:19 hannes Exp $ (LBL)";
-#endif
+/* \summary: Multi-Protocol Label Switching (MPLS) printer */
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
-#include <tcpdump-stdinc.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <netdissect-stdinc.h>
 
 
-#include "addrtoname.h"
-#include "interface.h"
-#include "extract.h"                   /* must come after interface.h */
+#include "netdissect.h"
+#include "extract.h"
 #include "mpls.h"
 
 static const char *mpls_labelname[] = {
 #include "mpls.h"
 
 static const char *mpls_labelname[] = {
@@ -54,130 +46,171 @@ static const char *mpls_labelname[] = {
 /*15*/ "rsvd",
 };
 
 /*15*/ "rsvd",
 };
 
+enum mpls_packet_type {
+       PT_UNKNOWN,
+       PT_IPV4,
+       PT_IPV6,
+       PT_OSI
+};
+
 /*
  * RFC3032: MPLS label stack encoding
  */
 void
 /*
  * RFC3032: MPLS label stack encoding
  */
 void
-mpls_print(const u_char *bp, u_int length)
+mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
 {
        const u_char *p;
 {
        const u_char *p;
-       u_int32_t label_entry;
-        u_int16_t label_stack_depth = 0;
+       uint32_t label_entry;
+       uint16_t label_stack_depth = 0;
+       enum mpls_packet_type pt = PT_UNKNOWN;
 
        p = bp;
 
        p = bp;
-       printf("MPLS");
+       ND_PRINT((ndo, "MPLS"));
        do {
        do {
-               TCHECK2(*p, sizeof(label_entry));
+               ND_TCHECK2(*p, sizeof(label_entry));
+               if (length < sizeof(label_entry)) {
+                       ND_PRINT((ndo, "[|MPLS], length %u", length));
+                       return;
+               }
                label_entry = EXTRACT_32BITS(p);
                label_entry = EXTRACT_32BITS(p);
-               printf("%s(label %u",
-                       label_stack_depth ? "\n\t" : " ",
-                       MPLS_LABEL(label_entry));
-                label_stack_depth++;
-               if (vflag &&
+               ND_PRINT((ndo, "%s(label %u",
+                      (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
+                              MPLS_LABEL(label_entry)));
+               label_stack_depth++;
+               if (ndo->ndo_vflag &&
                    MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
                    MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
-                       printf(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
-               printf(", exp %u", MPLS_EXP(label_entry));
+                       ND_PRINT((ndo, " (%s)", mpls_labelname[MPLS_LABEL(label_entry)]));
+               ND_PRINT((ndo, ", exp %u", MPLS_EXP(label_entry)));
                if (MPLS_STACK(label_entry))
                if (MPLS_STACK(label_entry))
-                       printf(", [S]");
-               printf(", ttl %u)", MPLS_TTL(label_entry));
+                       ND_PRINT((ndo, ", [S]"));
+               ND_PRINT((ndo, ", ttl %u)", MPLS_TTL(label_entry)));
 
                p += sizeof(label_entry);
 
                p += sizeof(label_entry);
+               length -= sizeof(label_entry);
        } while (!MPLS_STACK(label_entry));
 
        } while (!MPLS_STACK(label_entry));
 
+       /*
+        * Try to figure out the packet type.
+        */
        switch (MPLS_LABEL(label_entry)) {
        switch (MPLS_LABEL(label_entry)) {
+
        case 0: /* IPv4 explicit NULL label */
        case 0: /* IPv4 explicit NULL label */
-        case 3:        /* IPv4 implicit NULL label */
-                if (vflag>0) {
-                        printf("\n\t");
-                        ip_print(gndo, p, length - (p - bp));
-                }
-                else printf(", IP, length: %u",length);
+       case 3: /* IPv4 implicit NULL label */
+               pt = PT_IPV4;
                break;
                break;
-#ifdef INET6
+
        case 2: /* IPv6 explicit NULL label */
        case 2: /* IPv6 explicit NULL label */
-                if (vflag>0) {
-                        printf("\n\t");
-                        ip6_print(p, length - (p - bp));
-                }
-                else printf(", IPv6, length: %u",length);
+               pt = PT_IPV6;
                break;
                break;
-#endif
+
        default:
                /*
                 * Generally there's no indication of protocol in MPLS label
        default:
                /*
                 * Generally there's no indication of protocol in MPLS label
-                * encoding, however draft-hsmit-isis-aal5mux-00.txt describes
-                 * a technique that looks at the first payload byte if the BOS (bottom of stack)
-                 * bit is set and tries to determine the network layer protocol
-                 * 0x45-0x4f is IPv4
-                 * 0x60-0x6f is IPv6
-                 * 0x81-0x83 is OSI (CLNP,ES-IS,IS-IS)
-                 * this technique is sometimes known as NULL encapsulation
-                 * and decoding is particularly useful for control-plane traffic [BGP]
-                 * which cisco by default sends MPLS encapsulated
+                * encoding.
+                *
+                * However, draft-hsmit-isis-aal5mux-00.txt describes a
+                * technique for encapsulating IS-IS and IP traffic on the
+                * same ATM virtual circuit; you look at the first payload
+                * byte to determine the network layer protocol, based on
+                * the fact that
+                *
+                *      1) the first byte of an IP header is 0x45-0x4f
+                *         for IPv4 and 0x60-0x6f for IPv6;
+                *
+                *      2) the first byte of an OSI CLNP packet is 0x81,
+                *         the first byte of an OSI ES-IS packet is 0x82,
+                *         and the first byte of an OSI IS-IS packet is
+                *         0x83;
+                *
+                * so the network layer protocol can be inferred from the
+                * first byte of the packet, if the protocol is one of the
+                * ones listed above.
+                *
+                * Cisco sends control-plane traffic MPLS-encapsulated in
+                * this fashion.
                 */
                 */
+               ND_TCHECK(*p);
+               if (length < 1) {
+                       /* nothing to print */
+                       return;
+               }
+               switch(*p) {
 
 
-                if (MPLS_STACK(label_entry)) { /* only do this if the stack bit is set */
-                    switch(*p) {
-                    case 0x45:
-                    case 0x46:
-                    case 0x47:
-                    case 0x48:
-                    case 0x49:
-                    case 0x4a:
-                    case 0x4b:
-                    case 0x4c:
-                    case 0x4d:
-                    case 0x4e:
-                    case 0x4f:
-                       if (vflag>0) {
-                            printf("\n\t");
-                            ip_print(gndo, p, length - (p - bp));
-                           }
-                        else printf(", IP, length: %u",length);
-                        break;
-#ifdef INET6
-                    case 0x60:
-                    case 0x61:
-                    case 0x62:
-                    case 0x63:
-                    case 0x64:
-                    case 0x65:
-                    case 0x66:
-                    case 0x67:
-                    case 0x68:
-                    case 0x69:
-                    case 0x6a:
-                    case 0x6b:
-                    case 0x6c:
-                    case 0x6d:
-                    case 0x6e:
-                    case 0x6f:
-                       if (vflag>0) {
-                            printf("\n\t");
-                            ip6_print(p, length - (p - bp));
-                            }
-                       else printf(", IPv6, length: %u",length);
-                        break;
-#endif
-                    case 0x81:
-                    case 0x82:
-                    case 0x83:
-                       if (vflag>0) {
-                            printf("\n\t");
-                            isoclns_print(p, length - (p - bp), length - (p - bp));
-                           }
-                       else printf(", OSI, length: %u",length);
-                        break;
-                    default:
-                        /* ok bail out - we did not figure out what it is*/
-                        break;
-                    }
-                }
-                return;
+               case 0x45:
+               case 0x46:
+               case 0x47:
+               case 0x48:
+               case 0x49:
+               case 0x4a:
+               case 0x4b:
+               case 0x4c:
+               case 0x4d:
+               case 0x4e:
+               case 0x4f:
+                       pt = PT_IPV4;
+                       break;
+
+               case 0x60:
+               case 0x61:
+               case 0x62:
+               case 0x63:
+               case 0x64:
+               case 0x65:
+               case 0x66:
+               case 0x67:
+               case 0x68:
+               case 0x69:
+               case 0x6a:
+               case 0x6b:
+               case 0x6c:
+               case 0x6d:
+               case 0x6e:
+               case 0x6f:
+                       pt = PT_IPV6;
+                       break;
+
+               case 0x81:
+               case 0x82:
+               case 0x83:
+                       pt = PT_OSI;
+                       break;
+
+               default:
+                       /* ok bail out - we did not figure out what it is*/
+                       break;
+               }
+       }
+
+       /*
+        * Print the payload.
+        */
+       if (pt == PT_UNKNOWN) {
+               if (!ndo->ndo_suppress_default_print)
+                       ND_DEFAULTPRINT(p, length - (p - bp));
+               return;
+       }
+       ND_PRINT((ndo, ndo->ndo_vflag ? "\n\t" : " "));
+       switch (pt) {
+
+       case PT_IPV4:
+               ip_print(ndo, p, length - (p - bp));
+               break;
+
+       case PT_IPV6:
+               ip6_print(ndo, p, length - (p - bp));
+               break;
+
+       case PT_OSI:
+               isoclns_print(ndo, p, length - (p - bp), length - (p - bp));
+               break;
+
+       default:
+               break;
        }
        }
+       return;
 
 trunc:
 
 trunc:
-       printf("[|MPLS]");
+       ND_PRINT((ndo, "[|MPLS]"));
 }
 
 
 }
 
 
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