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29 /* \summary: Multi-Protocol Label Switching (MPLS) printer */
35 #include "netdissect-stdinc.h"
37 #define ND_LONGJMP_FROM_TCHECK
38 #include "netdissect.h"
42 static const char *mpls_labelname[] = {
43 /*0*/ "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
44 "implicit NULL", "rsvd",
45 /*5*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
46 /*10*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
50 enum mpls_packet_type {
58 * RFC3032: MPLS label stack encoding
61 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
65 uint16_t label_stack_depth = 0;
67 enum mpls_packet_type pt = PT_UNKNOWN;
69 ndo->ndo_protocol = "mpls";
71 nd_print_protocol_caps(ndo);
73 if (length < sizeof(label_entry))
75 label_entry = GET_BE_U_4(p);
76 ND_PRINT("%s(label %u",
77 (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
78 MPLS_LABEL(label_entry));
81 MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
82 ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
83 ND_PRINT(", exp %u", MPLS_EXP(label_entry));
84 if (MPLS_STACK(label_entry))
86 ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));
88 p += sizeof(label_entry);
89 length -= sizeof(label_entry);
90 } while (!MPLS_STACK(label_entry));
93 * Try to figure out the packet type.
95 switch (MPLS_LABEL(label_entry)) {
97 case 0: /* IPv4 explicit NULL label */
98 case 3: /* IPv4 implicit NULL label */
102 case 2: /* IPv6 explicit NULL label */
108 * Generally there's no indication of protocol in MPLS label
111 * However, draft-hsmit-isis-aal5mux-00.txt describes a
112 * technique for encapsulating IS-IS and IP traffic on the
113 * same ATM virtual circuit; you look at the first payload
114 * byte to determine the network layer protocol, based on
117 * 1) the first byte of an IP header is 0x45-0x4f
118 * for IPv4 and 0x60-0x6f for IPv6;
120 * 2) the first byte of an OSI CLNP packet is 0x81,
121 * the first byte of an OSI ES-IS packet is 0x82,
122 * and the first byte of an OSI IS-IS packet is
125 * so the network layer protocol can be inferred from the
126 * first byte of the packet, if the protocol is one of the
129 * Cisco sends control-plane traffic MPLS-encapsulated in
133 /* nothing to print */
138 (first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
139 (first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
140 (first >= 0x81 && first <= 0x83) ? PT_OSI :
141 /* ok bail out - we did not figure out what it is*/
150 if (!ndo->ndo_suppress_default_print)
151 ND_DEFAULTPRINT(p, length);
155 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
156 ip_print(ndo, p, length);
160 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
161 ip6_print(ndo, p, length);
165 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
166 isoclns_print(ndo, p, length);
172 nd_print_invalid(ndo);
173 ND_TCHECK_LEN(p, length);