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 <sys/cdefs.h> 26 #ifndef lint 27 __RCSID("$NetBSD: netdissect.c,v 1.4 2024/09/02 16:15:30 christos Exp $"); 28 #endif 29 30 #include <config.h> 31 32 #include "netdissect-stdinc.h" 33 #include "netdissect.h" 34 #include <string.h> 35 #include <stdio.h> 36 #include <stdlib.h> 37 38 #ifdef USE_LIBSMI 39 #include <smi.h> 40 #endif 41 42 /* 43 * Initialize anything that must be initialized before dissecting 44 * packets. 45 * 46 * This should be called at the beginning of the program; it does 47 * not need to be called, and should not be called, for every 48 * netdissect_options structure. 49 */ 50 int 51 nd_init(char *errbuf, size_t errbuf_size) 52 { 53 #ifdef _WIN32 54 WORD wVersionRequested; 55 WSADATA wsaData; 56 int err; 57 58 /* 59 * Request Winsock 2.2; we expect Winsock 2. 60 */ 61 wVersionRequested = MAKEWORD(2, 2); 62 err = WSAStartup(wVersionRequested, &wsaData); 63 if (err != 0) { 64 strlcpy(errbuf, "Attempting to initialize Winsock failed", 65 errbuf_size); 66 return (-1); 67 } 68 #endif /* _WIN32 */ 69 70 #ifdef USE_LIBSMI 71 /* 72 * XXX - should we just fail if this fails? Some of the 73 * libsmi calls may fail. 74 */ 75 smiInit("tcpdump"); 76 #endif 77 78 /* 79 * Clears the error buffer, and uses it so we don't get 80 * "unused argument" warnings at compile time. 81 */ 82 strlcpy(errbuf, "", errbuf_size); 83 return (0); 84 } 85 86 /* 87 * Clean up anything that ndo_init() did. 88 */ 89 void 90 nd_cleanup(void) 91 { 92 #ifdef USE_LIBSMI 93 /* 94 * This appears, in libsmi 0.4.8, to do nothing if smiInit() 95 * wasn't done or failed, so we call it unconditionally. 96 */ 97 smiExit(); 98 #endif 99 100 #ifdef _WIN32 101 /* 102 * Undo the WSAStartup() call above. 103 */ 104 WSACleanup(); 105 #endif 106 } 107 108 int 109 nd_have_smi_support(void) 110 { 111 #ifdef USE_LIBSMI 112 return (1); 113 #else 114 return (0); 115 #endif 116 } 117 118 /* 119 * Indicates whether an SMI module has been loaded, so that we can use 120 * libsmi to translate OIDs. 121 */ 122 int nd_smi_module_loaded; 123 124 int 125 nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size) 126 { 127 #ifdef USE_LIBSMI 128 if (smiLoadModule(module) == 0) { 129 snprintf(errbuf, errbuf_size, "could not load MIB module %s", 130 module); 131 return (-1); 132 } 133 nd_smi_module_loaded = 1; 134 return (0); 135 #else 136 snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support", 137 module); 138 return (-1); 139 #endif 140 } 141 142 const char * 143 nd_smi_version_string(void) 144 { 145 #ifdef USE_LIBSMI 146 return (smi_version_string); 147 #else 148 return (NULL); 149 #endif 150 } 151 152 153 int 154 nd_push_buffer(netdissect_options *ndo, u_char *new_buffer, 155 const u_char *new_packetp, const u_int newlen) 156 { 157 struct netdissect_saved_packet_info *ndspi; 158 159 ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info)); 160 if (ndspi == NULL) 161 return (0); /* fail */ 162 ndspi->ndspi_buffer = new_buffer; 163 ndspi->ndspi_packetp = ndo->ndo_packetp; 164 ndspi->ndspi_snapend = ndo->ndo_snapend; 165 ndspi->ndspi_prev = ndo->ndo_packet_info_stack; 166 167 ndo->ndo_packetp = new_packetp; 168 ndo->ndo_snapend = new_packetp + newlen; 169 ndo->ndo_packet_info_stack = ndspi; 170 171 return (1); /* success */ 172 } 173 174 175 /* 176 * In a given netdissect_options structure: 177 * 178 * push the current packet information onto the packet information 179 * stack; 180 * 181 * given a pointer into the packet and a length past that point in 182 * the packet, calculate a new snapshot end that's at the lower 183 * of the current snapshot end and that point in the packet; 184 * 185 * set the snapshot end to that new value. 186 */ 187 int 188 nd_push_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen) 189 { 190 struct netdissect_saved_packet_info *ndspi; 191 u_int snaplen_remaining; 192 193 ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info)); 194 if (ndspi == NULL) 195 return (0); /* fail */ 196 ndspi->ndspi_buffer = NULL; /* no new buffer */ 197 ndspi->ndspi_packetp = ndo->ndo_packetp; 198 ndspi->ndspi_snapend = ndo->ndo_snapend; 199 ndspi->ndspi_prev = ndo->ndo_packet_info_stack; 200 201 /* 202 * Push the saved previous data onto the stack. 203 */ 204 ndo->ndo_packet_info_stack = ndspi; 205 206 /* 207 * Find out how many bytes remain after the current snapend. 208 * 209 * We're restricted to packets with at most UINT_MAX bytes; 210 * cast the result to u_int, so that we don't get truncation 211 * warnings on LP64 and LLP64 platforms. (ptrdiff_t is 212 * signed and we want an unsigned difference; the pointer 213 * should at most be equal to snapend, and must *never* 214 * be past snapend.) 215 */ 216 snaplen_remaining = (u_int)(ndo->ndo_snapend - bp); 217 218 /* 219 * If the new snapend is smaller than the one calculated 220 * above, set the snapend to that value, otherwise leave 221 * it unchanged. 222 */ 223 if (newlen <= snaplen_remaining) { 224 /* Snapend isn't past the previous snapend */ 225 ndo->ndo_snapend = bp + newlen; 226 } 227 228 return (1); /* success */ 229 } 230 231 /* 232 * In a given netdissect_options structure: 233 * 234 * given a pointer into the packet and a length past that point in 235 * the packet, calculate a new snapshot end that's at the lower 236 * of the previous snapshot end - or, if there is no previous 237 * snapshot end, the current snapshot end - and that point in the 238 * packet; 239 * 240 * set the snapshot end to that new value. 241 * 242 * This is to change the current snapshot end. This may increase the 243 * snapshot end, as it may be used, for example, for a Jumbo Payload 244 * option in IPv6. It must not increase it past the snapshot length 245 * atop which the current one was pushed, however. 246 */ 247 void 248 nd_change_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen) 249 { 250 struct netdissect_saved_packet_info *ndspi; 251 const u_char *previous_snapend; 252 u_int snaplen_remaining; 253 254 ndspi = ndo->ndo_packet_info_stack; 255 if (ndspi->ndspi_prev != NULL) 256 previous_snapend = ndspi->ndspi_prev->ndspi_snapend; 257 else 258 previous_snapend = ndo->ndo_snapend; 259 260 /* 261 * Find out how many bytes remain after the previous 262 * snapend - or, if there is no previous snapend, after 263 * the current snapend. 264 * 265 * We're restricted to packets with at most UINT_MAX bytes; 266 * cast the result to u_int, so that we don't get truncation 267 * warnings on LP64 and LLP64 platforms. (ptrdiff_t is 268 * signed and we want an unsigned difference; the pointer 269 * should at most be equal to snapend, and must *never* 270 * be past snapend.) 271 */ 272 snaplen_remaining = (u_int)(previous_snapend - bp); 273 274 /* 275 * If the new snapend is smaller than the one calculated 276 * above, set the snapend to that value, otherwise leave 277 * it unchanged. 278 */ 279 if (newlen <= snaplen_remaining) { 280 /* Snapend isn't past the previous snapend */ 281 ndo->ndo_snapend = bp + newlen; 282 } 283 } 284 285 void 286 nd_pop_packet_info(netdissect_options *ndo) 287 { 288 struct netdissect_saved_packet_info *ndspi; 289 290 ndspi = ndo->ndo_packet_info_stack; 291 ndo->ndo_packetp = ndspi->ndspi_packetp; 292 ndo->ndo_snapend = ndspi->ndspi_snapend; 293 ndo->ndo_packet_info_stack = ndspi->ndspi_prev; 294 295 free(ndspi->ndspi_buffer); 296 free(ndspi); 297 } 298 299 void 300 nd_pop_all_packet_info(netdissect_options *ndo) 301 { 302 while (ndo->ndo_packet_info_stack != NULL) 303 nd_pop_packet_info(ndo); 304 } 305 306 NORETURN void 307 nd_trunc_longjmp(netdissect_options *ndo) 308 { 309 longjmp(ndo->ndo_early_end, ND_TRUNCATED); 310 #ifdef _AIX 311 /* 312 * In AIX <setjmp.h> decorates longjmp() with "#pragma leaves", which tells 313 * XL C that the function is noreturn, but GCC remains unaware of that and 314 * yields a "'noreturn' function does return" warning. 315 */ 316 ND_UNREACHABLE 317 #endif /* _AIX */ 318 } 319