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 
37 static const char tstr[] = " [|NSH]";
38 static 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 
48 void
nsh_print(netdissect_options * ndo,const u_char * bp,u_int len)49 nsh_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 
182 trunc:
183     ND_PRINT((ndo, "%s", tstr));
184 }
185 
186