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
38static 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
65static 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
80static 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
91void
92nsh_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
261invalid:
262    nd_print_invalid(ndo);
263}
264
265