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29 /* \summary: Multi-Protocol Label Switching (MPLS) printer */
35 #include <netdissect-stdinc.h>
37 #include "netdissect.h"
41 static const char *mpls_labelname[] = {
42 /*0*/ "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
43 "implicit NULL", "rsvd",
44 /*5*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
45 /*10*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
49 enum mpls_packet_type {
57 * RFC3032: MPLS label stack encoding
60 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
64 uint16_t label_stack_depth = 0;
65 enum mpls_packet_type pt = PT_UNKNOWN;
68 ND_PRINT((ndo, "MPLS"));
70 ND_TCHECK2(*p, sizeof(label_entry));
71 if (length < sizeof(label_entry)) {
72 ND_PRINT((ndo, "[|MPLS], length %u", length));
75 label_entry = EXTRACT_32BITS(p);
76 ND_PRINT((ndo, "%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((ndo, " (%s)", mpls_labelname[MPLS_LABEL(label_entry)]));
83 ND_PRINT((ndo, ", exp %u", MPLS_EXP(label_entry)));
84 if (MPLS_STACK(label_entry))
85 ND_PRINT((ndo, ", [S]"));
86 ND_PRINT((ndo, ", 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
134 /* nothing to print */
179 /* ok bail out - we did not figure out what it is*/
187 if (pt == PT_UNKNOWN) {
188 if (!ndo->ndo_suppress_default_print)
189 ND_DEFAULTPRINT(p, length);
192 ND_PRINT((ndo, ndo->ndo_vflag ? "\n\t" : " "));
196 ip_print(ndo, p, length);
200 ip6_print(ndo, p, length);
204 isoclns_print(ndo, p, length);
213 ND_PRINT((ndo, "[|MPLS]"));
219 * c-style: whitesmith