diff options
Diffstat (limited to 'contrib/tcpdump/print-mpls.c')
-rw-r--r-- | contrib/tcpdump/print-mpls.c | 202 |
1 files changed, 120 insertions, 82 deletions
diff --git a/contrib/tcpdump/print-mpls.c b/contrib/tcpdump/print-mpls.c index c6b0814..d97cce5 100644 --- a/contrib/tcpdump/print-mpls.c +++ b/contrib/tcpdump/print-mpls.c @@ -54,6 +54,13 @@ static const char *mpls_labelname[] = { /*15*/ "rsvd", }; +enum mpls_packet_type { + PT_UNKNOWN, + PT_IPV4, + PT_IPV6, + PT_OSI +}; + /* * RFC3032: MPLS label stack encoding */ @@ -62,7 +69,8 @@ mpls_print(const u_char *bp, u_int length) { const u_char *p; u_int32_t label_entry; - u_int16_t label_stack_depth = 0; + u_int16_t label_stack_depth = 0; + enum mpls_packet_type pt = PT_UNKNOWN; p = bp; printf("MPLS"); @@ -70,9 +78,9 @@ mpls_print(const u_char *bp, u_int length) TCHECK2(*p, sizeof(label_entry)); label_entry = EXTRACT_32BITS(p); printf("%s(label %u", - label_stack_depth ? "\n\t" : " ", - MPLS_LABEL(label_entry)); - label_stack_depth++; + (label_stack_depth && vflag) ? "\n\t" : " ", + MPLS_LABEL(label_entry)); + label_stack_depth++; if (vflag && MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0])) printf(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]); @@ -84,97 +92,127 @@ mpls_print(const u_char *bp, u_int length) p += sizeof(label_entry); } while (!MPLS_STACK(label_entry)); + /* + * Try to figure out the packet type. + */ switch (MPLS_LABEL(label_entry)) { + 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; -#ifdef INET6 + 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; -#endif + 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. */ + switch(*p) { + + 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; + } + } - 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; + /* + * Print the payload. + */ + if (pt == PT_UNKNOWN) { + if (!suppress_default_print) + default_print(p, length - (p - bp)); + return; + } + if (vflag) + printf("\n\t"); + else + printf(" "); + switch (pt) { + + case PT_IPV4: + ip_print(gndo, p, length - (p - bp)); + break; + + case PT_IPV6: #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; + ip6_print(gndo, p, length - (p - bp)); +#else + printf("IPv6, length: %u", length); #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; + break; + + case PT_OSI: + isoclns_print(p, length - (p - bp), length - (p - bp)); + break; + + default: + break; } + return; trunc: printf("[|MPLS]"); |