1 /* Copyright (c) 2015, bugyo
2 * All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 * 1. Redistributions of source code must retain the above copyright notice,
7 * this list of conditions and the following disclaimer.
8 * 2. Redistributions in binary form must reproduce the above copyright notice,
9 * this list of conditions and the following disclaimer in the documentation
10 * and/or other materials provided with the distribution.
11 *
12 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
13 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
14 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
15 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
16 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
17 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
18 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
19 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
20 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
21 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
22 */
23
24 /* \summary: Network Service Header (NSH) printer */
25
26 /* specification: RFC 8300 */
27
28 #ifdef HAVE_CONFIG_H
29 #include <config.h>
30 #endif
31
32 #include "netdissect-stdinc.h"
33
34 #define ND_LONGJMP_FROM_TCHECK
35 #include "netdissect.h"
36 #include "extract.h"
37
38 static const struct tok nsh_flags [] = {
39 { 0x2, "O" },
40 { 0, NULL }
41 };
42
43 /*
44 * 0 1 2 3
45 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
46 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
47 * |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol |
48 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
49 */
50 #define NSH_BASE_HDR_LEN 4
51 #define NSH_VER(x) (((x) & 0xc0000000) >> 30)
52 #define NSH_FLAGS(x) (((x) & 0x30000000) >> 28)
53 #define NSH_TTL(x) (((x) & 0x0fc00000) >> 22)
54 #define NSH_LENGTH(x) (((x) & 0x003f0000) >> 16)
55 #define NSH_MD_TYPE(x) (((x) & 0x00000f00) >> 8)
56 #define NSH_NEXT_PROT(x) (((x) & 0x000000ff) >> 0)
57
58 #define NSH_SERVICE_PATH_HDR_LEN 4
59 #define NSH_HDR_WORD_SIZE 4U
60
61 #define MD_RSV 0x00
62 #define MD_TYPE1 0x01
63 #define MD_TYPE2 0x02
64 #define MD_EXP 0x0F
65 static const struct tok md_str[] = {
66 { MD_RSV, "reserved" },
67 { MD_TYPE1, "1" },
68 { MD_TYPE2, "2" },
69 { MD_EXP, "experimental" },
70 { 0, NULL }
71 };
72
73 #define NP_IPV4 0x01
74 #define NP_IPV6 0x02
75 #define NP_ETH 0x03
76 #define NP_NSH 0x04
77 #define NP_MPLS 0x05
78 #define NP_EXP1 0xFE
79 #define NP_EXP2 0xFF
80 static const struct tok np_str[] = {
81 { NP_IPV4, "IPv4" },
82 { NP_IPV6, "IPv6" },
83 { NP_ETH, "Ethernet" },
84 { NP_NSH, "NSH" },
85 { NP_MPLS, "MPLS" },
86 { NP_EXP1, "Experiment 1" },
87 { NP_EXP2, "Experiment 2" },
88 { 0, NULL }
89 };
90
91 void
nsh_print(netdissect_options * ndo,const u_char * bp,u_int len)92 nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
93 {
94 uint32_t basehdr;
95 u_int ver, length, md_type;
96 uint8_t next_protocol;
97 u_char past_headers = 0;
98 u_int next_len;
99
100 ndo->ndo_protocol = "nsh";
101 /*
102 * 0 1 2 3
103 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
104 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105 * | Base Header |
106 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107 * | Service Path Header |
108 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109 * | |
110 * ~ Context Header(s) ~
111 * | |
112 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113 */
114
115 /* print Base Header and Service Path Header */
116 if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN) {
117 ND_PRINT(" (packet length %u < %u)",
118 len, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
119 goto invalid;
120 }
121
122 basehdr = GET_BE_U_4(bp);
123 bp += 4;
124 ver = NSH_VER(basehdr);
125 length = NSH_LENGTH(basehdr);
126 md_type = NSH_MD_TYPE(basehdr);
127 next_protocol = NSH_NEXT_PROT(basehdr);
128
129 ND_PRINT("NSH, ");
130 if (ndo->ndo_vflag > 1) {
131 ND_PRINT("ver %u, ", ver);
132 }
133 if (ver != 0)
134 return;
135 ND_PRINT("flags [%s], ",
136 bittok2str_nosep(nsh_flags, "none", NSH_FLAGS(basehdr)));
137 if (ndo->ndo_vflag > 2) {
138 ND_PRINT("TTL %u, ", NSH_TTL(basehdr));
139 ND_PRINT("length %u, ", length);
140 ND_PRINT("md type %s, ", tok2str(md_str, "unknown (0x%02x)", md_type));
141 }
142 if (ndo->ndo_vflag > 1) {
143 ND_PRINT("next-protocol %s, ",
144 tok2str(np_str, "unknown (0x%02x)", next_protocol));
145 }
146
147 /* Make sure we have all the headers */
148 if (len < length * NSH_HDR_WORD_SIZE) {
149 ND_PRINT(" (too many headers for packet length %u)", len);
150 goto invalid;
151 }
152
153 /*
154 * 0 1 2 3
155 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
156 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
157 * | Service Path Identifier (SPI) | Service Index |
158 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
159 *
160 */
161 ND_PRINT("service-path-id 0x%06x, ", GET_BE_U_3(bp));
162 bp += 3;
163 ND_PRINT("service-index 0x%x", GET_U_1(bp));
164 bp += 1;
165
166 /*
167 * length includes the lengths of the Base and Service Path headers.
168 * That means it must be at least 2.
169 */
170 if (length < 2) {
171 ND_PRINT(" (less than two headers)");
172 goto invalid;
173 }
174
175 /*
176 * Print, or skip, the Context Headers.
177 * (length - 2) is the length of those headers.
178 */
179 if (ndo->ndo_vflag > 2) {
180 u_int n;
181
182 if (md_type == MD_TYPE1) {
183 if (length != 6) {
184 ND_PRINT(" (invalid length for the MD type)");
185 goto invalid;
186 }
187 for (n = 0; n < length - 2; n++) {
188 ND_PRINT("\n Context[%02u]: 0x%08x", n, GET_BE_U_4(bp));
189 bp += NSH_HDR_WORD_SIZE;
190 }
191 past_headers = 1;
192 }
193 else if (md_type == MD_TYPE2) {
194 n = 0;
195 while (n < length - 2) {
196 uint16_t tlv_class;
197 uint8_t tlv_type, tlv_len, tlv_len_padded;
198
199 tlv_class = GET_BE_U_2(bp);
200 bp += 2;
201 tlv_type = GET_U_1(bp);
202 bp += 1;
203 tlv_len = GET_U_1(bp) & 0x7f;
204 bp += 1;
205 tlv_len_padded = roundup2(tlv_len, NSH_HDR_WORD_SIZE);
206
207 ND_PRINT("\n TLV Class %u, Type %u, Len %u",
208 tlv_class, tlv_type, tlv_len);
209
210 n += 1;
211
212 if (length - 2 < n + tlv_len_padded / NSH_HDR_WORD_SIZE) {
213 ND_PRINT(" (length too big)");
214 goto invalid;
215 }
216
217 if (tlv_len) {
218 const char *sep = "0x";
219 u_int vn;
220
221 ND_PRINT("\n Value: ");
222 for (vn = 0; vn < tlv_len; vn++) {
223 ND_PRINT("%s%02x", sep, GET_U_1(bp));
224 bp += 1;
225 sep = ":";
226 }
227 /* Cover any TLV padding. */
228 ND_TCHECK_LEN(bp, tlv_len_padded - tlv_len);
229 bp += tlv_len_padded - tlv_len;
230 n += tlv_len_padded / NSH_HDR_WORD_SIZE;
231 }
232 }
233 past_headers = 1;
234 }
235 }
236 if (! past_headers) {
237 ND_TCHECK_LEN(bp, (length - 2) * NSH_HDR_WORD_SIZE);
238 bp += (length - 2) * NSH_HDR_WORD_SIZE;
239 }
240 ND_PRINT(ndo->ndo_vflag ? "\n " : ": ");
241
242 /* print Next Protocol */
243 next_len = len - length * NSH_HDR_WORD_SIZE;
244 switch (next_protocol) {
245 case NP_IPV4:
246 ip_print(ndo, bp, next_len);
247 break;
248 case NP_IPV6:
249 ip6_print(ndo, bp, next_len);
250 break;
251 case NP_ETH:
252 ether_print(ndo, bp, next_len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
253 break;
254 default:
255 ND_PRINT("ERROR: unknown-next-protocol");
256 return;
257 }
258
259 return;
260
261 invalid:
262 nd_print_invalid(ndo);
263 }
264
265