tcpdump  4.99.1
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netdissect.c
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1 /*
2  * Copyright (c) 1988-1997
3  * The Regents of the University of California. All rights reserved.
4  *
5  * Copyright (c) 1998-2012 Michael Richardson <mcr@tcpdump.org>
6  * The TCPDUMP project
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that: (1) source code distributions
10  * retain the above copyright notice and this paragraph in its entirety, (2)
11  * distributions including binary code include the above copyright notice and
12  * this paragraph in its entirety in the documentation or other materials
13  * provided with the distribution, and (3) all advertising materials mentioning
14  * features or use of this software display the following acknowledgement:
15  * ``This product includes software developed by the University of California,
16  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
17  * the University nor the names of its contributors may be used to endorse
18  * or promote products derived from this software without specific prior
19  * written permission.
20  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
21  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
22  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
23  */
24 
25 #ifdef HAVE_CONFIG_H
26 #include <config.h>
27 #endif
28 
29 #include "netdissect-stdinc.h"
30 #include "netdissect.h"
31 #include <string.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 
35 #ifdef USE_LIBSMI
36 #include <smi.h>
37 #endif
38 
39 /*
40  * Initialize anything that must be initialized before dissecting
41  * packets.
42  *
43  * This should be called at the beginning of the program; it does
44  * not need to be called, and should not be called, for every
45  * netdissect_options structure.
46  */
47 int
48 nd_init(char *errbuf, size_t errbuf_size)
49 {
50 #ifdef _WIN32
51  WORD wVersionRequested;
52  WSADATA wsaData;
53  int err;
54 
55  /*
56  * Request Winsock 2.2; we expect Winsock 2.
57  */
58  wVersionRequested = MAKEWORD(2, 2);
59  err = WSAStartup(wVersionRequested, &wsaData);
60  if (err != 0) {
61  strlcpy(errbuf, "Attempting to initialize Winsock failed",
62  errbuf_size);
63  return (-1);
64  }
65 #endif /* _WIN32 */
66 
67 #ifdef USE_LIBSMI
68  /*
69  * XXX - should we just fail if this fails? Some of the
70  * libsmi calls may fail.
71  */
72  smiInit("tcpdump");
73 #endif
74 
75  /*
76  * Clears the error buffer, and uses it so we don't get
77  * "unused argument" warnings at compile time.
78  */
79  strlcpy(errbuf, "", errbuf_size);
80  return (0);
81 }
82 
83 /*
84  * Clean up anything that ndo_init() did.
85  */
86 void
88 {
89 #ifdef USE_LIBSMI
90  /*
91  * This appears, in libsmi 0.4.8, to do nothing if smiInit()
92  * wasn't done or failed, so we call it unconditionally.
93  */
94  smiExit();
95 #endif
96 
97 #ifdef _WIN32
98  /*
99  * Undo the WSAStartup() call above.
100  */
101  WSACleanup();
102 #endif
103 }
104 
105 int
107 {
108 #ifdef USE_LIBSMI
109  return (1);
110 #else
111  return (0);
112 #endif
113 }
114 
115 /*
116  * Indicates whether an SMI module has been loaded, so that we can use
117  * libsmi to translate OIDs.
118  */
120 
121 int
122 nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size)
123 {
124 #ifdef USE_LIBSMI
125  if (smiLoadModule(module) == 0) {
126  snprintf(errbuf, errbuf_size, "could not load MIB module %s",
127  module);
128  return (-1);
129  }
131  return (0);
132 #else
133  snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support",
134  module);
135  return (-1);
136 #endif
137 }
138 
139 const char *
141 {
142 #ifdef USE_LIBSMI
143  return (smi_version_string);
144 #else
145  return (NULL);
146 #endif
147 }
148 
149 
150 int
151 nd_push_buffer(netdissect_options *ndo, u_char *new_buffer,
152  const u_char *new_packetp, const u_char *new_snapend)
153 {
154  struct netdissect_saved_packet_info *ndspi;
155 
156  ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
157  if (ndspi == NULL)
158  return (0); /* fail */
159  ndspi->ndspi_buffer = new_buffer;
160  ndspi->ndspi_packetp = ndo->ndo_packetp;
161  ndspi->ndspi_snapend = ndo->ndo_snapend;
162  ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
163 
164  ndo->ndo_packetp = new_packetp;
165  ndo->ndo_snapend = new_snapend;
166  ndo->ndo_packet_info_stack = ndspi;
167 
168  return (1); /* success */
169 }
170 
171 /*
172  * Set a new snapshot end to the minimum of the existing snapshot end
173  * and the new snapshot end.
174  */
175 int
176 nd_push_snapend(netdissect_options *ndo, const u_char *new_snapend)
177 {
178  struct netdissect_saved_packet_info *ndspi;
179 
180  ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
181  if (ndspi == NULL)
182  return (0); /* fail */
183  ndspi->ndspi_buffer = NULL; /* no new buffer */
184  ndspi->ndspi_packetp = ndo->ndo_packetp;
185  ndspi->ndspi_snapend = ndo->ndo_snapend;
186  ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
187 
188  /* No new packet pointer, either */
189  if (new_snapend < ndo->ndo_snapend)
190  ndo->ndo_snapend = new_snapend;
191  ndo->ndo_packet_info_stack = ndspi;
192 
193  return (1); /* success */
194 }
195 
196 /*
197  * Change an already-pushed snapshot end. This may increase the
198  * snapshot end, as it may be used, for example, for a Jumbo Payload
199  * option in IPv6. It must not increase it past the snapshot length
200  * atop which the current one was pushed, however.
201  */
202 void
203 nd_change_snapend(netdissect_options *ndo, const u_char *new_snapend)
204 {
205  struct netdissect_saved_packet_info *ndspi;
206 
207  ndspi = ndo->ndo_packet_info_stack;
208  if (ndspi->ndspi_prev != NULL) {
209  if (new_snapend <= ndspi->ndspi_prev->ndspi_snapend)
210  ndo->ndo_snapend = new_snapend;
211  } else {
212  if (new_snapend < ndo->ndo_snapend)
213  ndo->ndo_snapend = new_snapend;
214  }
215 }
216 
217 void
219 {
220  struct netdissect_saved_packet_info *ndspi;
221 
222  ndspi = ndo->ndo_packet_info_stack;
223  ndo->ndo_packetp = ndspi->ndspi_packetp;
224  ndo->ndo_snapend = ndspi->ndspi_snapend;
225  ndo->ndo_packet_info_stack = ndspi->ndspi_prev;
226 
227  free(ndspi->ndspi_buffer);
228  free(ndspi);
229 }
230 
231 void
233 {
234  while (ndo->ndo_packet_info_stack != NULL)
235  nd_pop_packet_info(ndo);
236 }
size_t strlcpy(char *, const char *, size_t)
Definition: strlcpy.c:47
int nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size)
Definition: netdissect.c:122
int nd_push_snapend(netdissect_options *ndo, const u_char *new_snapend)
Definition: netdissect.c:176
void nd_change_snapend(netdissect_options *ndo, const u_char *new_snapend)
Definition: netdissect.c:203
const char * nd_smi_version_string(void)
Definition: netdissect.c:140
void nd_cleanup(void)
Definition: netdissect.c:87
int nd_push_buffer(netdissect_options *ndo, u_char *new_buffer, const u_char *new_packetp, const u_char *new_snapend)
Definition: netdissect.c:151
int nd_smi_module_loaded
Definition: netdissect.c:119
void nd_pop_all_packet_info(netdissect_options *ndo)
Definition: netdissect.c:232
void nd_pop_packet_info(netdissect_options *ndo)
Definition: netdissect.c:218
int nd_have_smi_support(void)
Definition: netdissect.c:106
int nd_init(char *errbuf, size_t errbuf_size)
Definition: netdissect.c:48
int snprintf(char *, size_t, const char *,...)
struct netdissect_saved_packet_info * ndo_packet_info_stack
Definition: netdissect.h:242
const u_char * ndo_snapend
Definition: netdissect.h:239
const u_char * ndo_packetp
Definition: netdissect.h:238
const u_char * ndspi_snapend
Definition: netdissect.h:193
const u_char * ndspi_packetp
Definition: netdissect.h:192
struct netdissect_saved_packet_info * ndspi_prev
Definition: netdissect.h:194