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 #include <config.h> 26 27 #include "netdissect-stdinc.h" 28 #include "netdissect.h" 29 #include <string.h> 30 #include <stdio.h> 31 #include <stdlib.h> 32 33 #ifdef USE_LIBSMI 34 #include <smi.h> 35 #endif 36 37 /* 38 * Initialize anything that must be initialized before dissecting 39 * packets. 40 * 41 * This should be called at the beginning of the program; it does 42 * not need to be called, and should not be called, for every 43 * netdissect_options structure. 44 */ 45 int 46 nd_init(char *errbuf, size_t errbuf_size) 47 { 48 #ifdef _WIN32 49 WORD wVersionRequested; 50 WSADATA wsaData; 51 int err; 52 53 /* 54 * Request Winsock 2.2; we expect Winsock 2. 55 */ 56 wVersionRequested = MAKEWORD(2, 2); 57 err = WSAStartup(wVersionRequested, &wsaData); 58 if (err != 0) { 59 strlcpy(errbuf, "Attempting to initialize Winsock failed", 60 errbuf_size); 61 return (-1); 62 } 63 #endif /* _WIN32 */ 64 65 #ifdef USE_LIBSMI 66 /* 67 * XXX - should we just fail if this fails? Some of the 68 * libsmi calls may fail. 69 */ 70 smiInit("tcpdump"); 71 #endif 72 73 /* 74 * Clears the error buffer, and uses it so we don't get 75 * "unused argument" warnings at compile time. 76 */ 77 strlcpy(errbuf, "", errbuf_size); 78 return (0); 79 } 80 81 /* 82 * Clean up anything that ndo_init() did. 83 */ 84 void 85 nd_cleanup(void) 86 { 87 #ifdef USE_LIBSMI 88 /* 89 * This appears, in libsmi 0.4.8, to do nothing if smiInit() 90 * wasn't done or failed, so we call it unconditionally. 91 */ 92 smiExit(); 93 #endif 94 95 #ifdef _WIN32 96 /* 97 * Undo the WSAStartup() call above. 98 */ 99 WSACleanup(); 100 #endif 101 } 102 103 int 104 nd_have_smi_support(void) 105 { 106 #ifdef USE_LIBSMI 107 return (1); 108 #else 109 return (0); 110 #endif 111 } 112 113 /* 114 * Indicates whether an SMI module has been loaded, so that we can use 115 * libsmi to translate OIDs. 116 */ 117 int nd_smi_module_loaded; 118 119 int 120 nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size) 121 { 122 #ifdef USE_LIBSMI 123 if (smiLoadModule(module) == 0) { 124 snprintf(errbuf, errbuf_size, "could not load MIB module %s", 125 module); 126 return (-1); 127 } 128 nd_smi_module_loaded = 1; 129 return (0); 130 #else 131 snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support", 132 module); 133 return (-1); 134 #endif 135 } 136 137 const char * 138 nd_smi_version_string(void) 139 { 140 #ifdef USE_LIBSMI 141 return (smi_version_string); 142 #else 143 return (NULL); 144 #endif 145 } 146 147 148 int 149 nd_push_buffer(netdissect_options *ndo, u_char *new_buffer, 150 const u_char *new_packetp, const u_int newlen) 151 { 152 struct netdissect_saved_packet_info *ndspi; 153 154 ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info)); 155 if (ndspi == NULL) 156 return (0); /* fail */ 157 ndspi->ndspi_buffer = new_buffer; 158 ndspi->ndspi_packetp = ndo->ndo_packetp; 159 ndspi->ndspi_snapend = ndo->ndo_snapend; 160 ndspi->ndspi_prev = ndo->ndo_packet_info_stack; 161 162 ndo->ndo_packetp = new_packetp; 163 ndo->ndo_snapend = new_packetp + newlen; 164 ndo->ndo_packet_info_stack = ndspi; 165 166 return (1); /* success */ 167 } 168 169 170 /* 171 * In a given netdissect_options structure: 172 * 173 * push the current packet information onto the packet information 174 * stack; 175 * 176 * given a pointer into the packet and a length past that point in 177 * the packet, calculate a new snapshot end that's at the lower 178 * of the current snapshot end and that point in the packet; 179 * 180 * set the snapshot end to that new value. 181 */ 182 int 183 nd_push_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen) 184 { 185 struct netdissect_saved_packet_info *ndspi; 186 u_int snaplen_remaining; 187 188 ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info)); 189 if (ndspi == NULL) 190 return (0); /* fail */ 191 ndspi->ndspi_buffer = NULL; /* no new buffer */ 192 ndspi->ndspi_packetp = ndo->ndo_packetp; 193 ndspi->ndspi_snapend = ndo->ndo_snapend; 194 ndspi->ndspi_prev = ndo->ndo_packet_info_stack; 195 196 /* 197 * Push the saved previous data onto the stack. 198 */ 199 ndo->ndo_packet_info_stack = ndspi; 200 201 /* 202 * Find out how many bytes remain after the current snapend. 203 * 204 * We're restricted to packets with at most UINT_MAX bytes; 205 * cast the result to u_int, so that we don't get truncation 206 * warnings on LP64 and LLP64 platforms. (ptrdiff_t is 207 * signed and we want an unsigned difference; the pointer 208 * should at most be equal to snapend, and must *never* 209 * be past snapend.) 210 */ 211 snaplen_remaining = (u_int)(ndo->ndo_snapend - bp); 212 213 /* 214 * If the new snapend is smaller than the one calculated 215 * above, set the snapend to that value, otherwise leave 216 * it unchanged. 217 */ 218 if (newlen <= snaplen_remaining) { 219 /* Snapend isn't past the previous snapend */ 220 ndo->ndo_snapend = bp + newlen; 221 } 222 223 return (1); /* success */ 224 } 225 226 /* 227 * In a given netdissect_options structure: 228 * 229 * given a pointer into the packet and a length past that point in 230 * the packet, calculate a new snapshot end that's at the lower 231 * of the previous snapshot end - or, if there is no previous 232 * snapshot end, the current snapshot end - and that point in the 233 * packet; 234 * 235 * set the snapshot end to that new value. 236 * 237 * This is to change the current snapshot end. This may increase the 238 * snapshot end, as it may be used, for example, for a Jumbo Payload 239 * option in IPv6. It must not increase it past the snapshot length 240 * atop which the current one was pushed, however. 241 */ 242 void 243 nd_change_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen) 244 { 245 struct netdissect_saved_packet_info *ndspi; 246 const u_char *previous_snapend; 247 u_int snaplen_remaining; 248 249 ndspi = ndo->ndo_packet_info_stack; 250 if (ndspi->ndspi_prev != NULL) 251 previous_snapend = ndspi->ndspi_prev->ndspi_snapend; 252 else 253 previous_snapend = ndo->ndo_snapend; 254 255 /* 256 * Find out how many bytes remain after the previous 257 * snapend - or, if there is no previous snapend, after 258 * the current snapend. 259 * 260 * We're restricted to packets with at most UINT_MAX bytes; 261 * cast the result to u_int, so that we don't get truncation 262 * warnings on LP64 and LLP64 platforms. (ptrdiff_t is 263 * signed and we want an unsigned difference; the pointer 264 * should at most be equal to snapend, and must *never* 265 * be past snapend.) 266 */ 267 snaplen_remaining = (u_int)(previous_snapend - bp); 268 269 /* 270 * If the new snapend is smaller than the one calculated 271 * above, set the snapend to that value, otherwise leave 272 * it unchanged. 273 */ 274 if (newlen <= snaplen_remaining) { 275 /* Snapend isn't past the previous snapend */ 276 ndo->ndo_snapend = bp + newlen; 277 } 278 } 279 280 void 281 nd_pop_packet_info(netdissect_options *ndo) 282 { 283 struct netdissect_saved_packet_info *ndspi; 284 285 ndspi = ndo->ndo_packet_info_stack; 286 ndo->ndo_packetp = ndspi->ndspi_packetp; 287 ndo->ndo_snapend = ndspi->ndspi_snapend; 288 ndo->ndo_packet_info_stack = ndspi->ndspi_prev; 289 290 free(ndspi->ndspi_buffer); 291 free(ndspi); 292 } 293 294 void 295 nd_pop_all_packet_info(netdissect_options *ndo) 296 { 297 while (ndo->ndo_packet_info_stack != NULL) 298 nd_pop_packet_info(ndo); 299 } 300 301 NORETURN void 302 nd_trunc_longjmp(netdissect_options *ndo) 303 { 304 longjmp(ndo->ndo_early_end, ND_TRUNCATED); 305 #ifdef _AIX 306 /* 307 * In AIX <setjmp.h> decorates longjmp() with "#pragma leaves", which tells 308 * XL C that the function is noreturn, but GCC remains unaware of that and 309 * yields a "'noreturn' function does return" warning. 310 */ 311 ND_UNREACHABLE 312 #endif /* _AIX */ 313 } 314