X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/21480b97d89d0edebe1cb706503a9bee117bd9db..HEAD:/print-mpls.c diff --git a/print-mpls.c b/print-mpls.c index c56f2643..a80b722f 100644 --- a/print-mpls.c +++ b/print-mpls.c @@ -26,38 +26,16 @@ * SUCH DAMAGE. */ -#ifndef lint -static const char rcsid[] _U_ = - "@(#) $Header: /tcpdump/master/tcpdump/print-mpls.c,v 1.11 2004-06-06 19:20:04 hannes Exp $ (LBL)"; -#endif - -#ifdef HAVE_CONFIG_H -#include "config.h" -#endif - -#include - -#include -#include -#include - -#include "addrtoname.h" -#include "interface.h" -#include "extract.h" /* must come after interface.h */ - -#define LABEL_MASK 0xfffff000 -#define LABEL_SHIFT 12 -#define EXP_MASK 0x00000e00 -#define EXP_SHIFT 9 -#define STACK_MASK 0x00000100 -#define STACK_SHIFT 8 -#define TTL_MASK 0x000000ff -#define TTL_SHIFT 0 - -#define MPLS_LABEL(x) (((x) & LABEL_MASK) >> LABEL_SHIFT) -#define MPLS_EXP(x) (((x) & EXP_MASK) >> EXP_SHIFT) -#define MPLS_STACK(x) (((x) & STACK_MASK) >> STACK_SHIFT) -#define MPLS_TTL(x) (((x) & TTL_MASK) >> TTL_SHIFT) +/* \summary: Multi-Protocol Label Switching (MPLS) printer */ + +#include + +#include "netdissect-stdinc.h" + +#define ND_LONGJMP_FROM_TCHECK +#include "netdissect.h" +#include "extract.h" +#include "mpls.h" static const char *mpls_labelname[] = { /*0*/ "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL", @@ -67,119 +45,128 @@ static const char *mpls_labelname[] = { /*15*/ "rsvd", }; +enum mpls_packet_type { + PT_UNKNOWN, + PT_IPV4, + PT_IPV6, + PT_OSI +}; + /* * 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; - u_int32_t v; + uint32_t label_entry; + uint16_t label_stack_depth = 0; + uint8_t first; + enum mpls_packet_type pt = PT_UNKNOWN; + ndo->ndo_protocol = "mpls"; p = bp; - printf("MPLS"); + nd_print_protocol_caps(ndo); do { - TCHECK2(*p, sizeof(v)); - v = EXTRACT_32BITS(p); - printf(" ("); /*)*/ - printf("label %u", MPLS_LABEL(v)); - if (vflag && - MPLS_LABEL(v) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0])) - printf(" (%s)", mpls_labelname[MPLS_LABEL(v)]); - printf(", exp %u", MPLS_EXP(v)); - if (MPLS_STACK(v)) - printf(", [S]"); - printf(", ttl %u", MPLS_TTL(v)); - /*(*/ - printf(")"); - - p += sizeof(v); - } while (!MPLS_STACK(v)); - - switch (MPLS_LABEL(v)) { + if (length < sizeof(label_entry)) + goto invalid; + label_entry = GET_BE_U_4(p); + ND_PRINT("%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])) + ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]); + ND_PRINT(", tc %u", MPLS_TC(label_entry)); + if (MPLS_STACK(label_entry)) + ND_PRINT(", [S]"); + ND_PRINT(", ttl %u)", MPLS_TTL(label_entry)); + + p += sizeof(label_entry); + length -= 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 */ - ip_print(p, length - (p - bp)); + case 3: /* IPv4 implicit NULL label */ + pt = PT_IPV4; break; -#ifdef INET6 + case 2: /* IPv6 explicit NULL label */ - ip6_print(p, length - (p - bp)); + 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. */ + if (length < 1) { + /* nothing to print */ + return; + } + first = GET_U_1(p); + pt = + (first >= 0x45 && first <= 0x4f) ? PT_IPV4 : + (first >= 0x60 && first <= 0x6f) ? PT_IPV6 : + (first >= 0x81 && first <= 0x83) ? PT_OSI : + /* ok bail out - we did not figure out what it is*/ + PT_UNKNOWN; + } - if (MPLS_STACK(v)) { /* 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(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; + /* + * Print the payload. + */ + switch (pt) { + case PT_UNKNOWN: + if (!ndo->ndo_suppress_default_print) + ND_DEFAULTPRINT(p, length); + break; + + case PT_IPV4: + ND_PRINT(ndo->ndo_vflag ? "\n\t" : " "); + ip_print(ndo, p, length); + break; + + case PT_IPV6: + ND_PRINT(ndo->ndo_vflag ? "\n\t" : " "); + ip6_print(ndo, p, length); + break; + + case PT_OSI: + ND_PRINT(ndo->ndo_vflag ? "\n\t" : " "); + isoclns_print(ndo, p, length); + break; } + return; -trunc: - printf("[|MPLS]"); +invalid: + nd_print_invalid(ndo); + ND_TCHECK_LEN(p, length); }