print-nsh.c revision 313537 
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: draft-ietf-sfc-nsh-01 */
27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include <netdissect-stdinc.h>
33
34#include "netdissect.h"
35#include "extract.h"
36
37static const char tstr[] = " [|NSH]";
38static const struct tok nsh_flags [] = {
39    { 0x20, "O" },
40    { 0x10, "C" },
41    { 0, NULL }
42};
43
44#define NSH_BASE_HDR_LEN 4
45#define NSH_SERVICE_PATH_HDR_LEN 4
46#define NSH_HDR_WORD_SIZE 4U
47
48void
49nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
50{
51    int n, vn;
52    uint8_t ver;
53    uint8_t flags;
54    uint8_t length;
55    uint8_t md_type;
56    uint8_t next_protocol;
57    uint32_t service_path_id;
58    uint8_t service_index;
59    uint32_t ctx;
60    uint16_t tlv_class;
61    uint8_t tlv_type;
62    uint8_t tlv_len;
63    u_int next_len;
64
65    /* print Base Header and Service Path Header */
66    if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN)
67        goto trunc;
68
69    ND_TCHECK2(*bp, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
70
71    ver = (uint8_t)(*bp >> 6);
72    flags = *bp;
73    bp += 1;
74    length = *bp;
75    bp += 1;
76    md_type = *bp;
77    bp += 1;
78    next_protocol = *bp;
79    bp += 1;
80    service_path_id = EXTRACT_24BITS(bp);
81    bp += 3;
82    service_index = *bp;
83    bp += 1;
84
85    ND_PRINT((ndo, "NSH, "));
86    if (ndo->ndo_vflag > 1) {
87        ND_PRINT((ndo, "ver %d, ", ver));
88    }
89    ND_PRINT((ndo, "flags [%s], ", bittok2str_nosep(nsh_flags, "none", flags)));
90    if (ndo->ndo_vflag > 2) {
91        ND_PRINT((ndo, "length %d, ", length));
92        ND_PRINT((ndo, "md type 0x%x, ", md_type));
93    }
94    if (ndo->ndo_vflag > 1) {
95        ND_PRINT((ndo, "next-protocol 0x%x, ", next_protocol));
96    }
97    ND_PRINT((ndo, "service-path-id 0x%06x, ", service_path_id));
98    ND_PRINT((ndo, "service-index 0x%x", service_index));
99
100    /* Make sure we have all the headers */
101    if (len < length * NSH_HDR_WORD_SIZE)
102        goto trunc;
103
104    ND_TCHECK2(*bp, length * NSH_HDR_WORD_SIZE);
105
106    /*
107     * length includes the lengths of the Base and Service Path headers.
108     * That means it must be at least 2.
109     */
110    if (length < 2)
111        goto trunc;
112
113    /*
114     * Print, or skip, the Context Headers.
115     * (length - 2) is the length of those headers.
116     */
117    if (ndo->ndo_vflag > 2) {
118        if (md_type == 0x01) {
119            for (n = 0; n < length - 2; n++) {
120                ctx = EXTRACT_32BITS(bp);
121                bp += NSH_HDR_WORD_SIZE;
122                ND_PRINT((ndo, "\n        Context[%02d]: 0x%08x", n, ctx));
123            }
124        }
125        else if (md_type == 0x02) {
126            n = 0;
127            while (n < length - 2) {
128                tlv_class = EXTRACT_16BITS(bp);
129                bp += 2;
130                tlv_type  = *bp;
131                bp += 1;
132                tlv_len   = *bp;
133                bp += 1;
134
135                ND_PRINT((ndo, "\n        TLV Class %d, Type %d, Len %d",
136                          tlv_class, tlv_type, tlv_len));
137
138                n += 1;
139
140                if (length - 2 < n + tlv_len) {
141                    ND_PRINT((ndo, " ERROR: invalid-tlv-length"));
142                    return;
143                }
144
145                for (vn = 0; vn < tlv_len; vn++) {
146                    ctx = EXTRACT_32BITS(bp);
147                    bp += NSH_HDR_WORD_SIZE;
148                    ND_PRINT((ndo, "\n            Value[%02d]: 0x%08x", vn, ctx));
149                }
150                n += tlv_len;
151            }
152        }
153        else {
154            ND_PRINT((ndo, "ERROR: unknown-next-protocol"));
155            return;
156        }
157    }
158    else {
159        bp += (length - 2) * NSH_HDR_WORD_SIZE;
160    }
161    ND_PRINT((ndo, ndo->ndo_vflag ? "\n    " : ": "));
162
163    /* print Next Protocol */
164    next_len = len - length * NSH_HDR_WORD_SIZE;
165    switch (next_protocol) {
166    case 0x1:
167        ip_print(ndo, bp, next_len);
168        break;
169    case 0x2:
170        ip6_print(ndo, bp, next_len);
171        break;
172    case 0x3:
173        ether_print(ndo, bp, next_len, ndo->ndo_snapend - bp, NULL, NULL);
174        break;
175    default:
176        ND_PRINT((ndo, "ERROR: unknown-next-protocol"));
177        return;
178    }
179
180    return;
181
182trunc:
183    ND_PRINT((ndo, "%s", tstr));
184}
185
186