The Tcpdump Group git mirrors - tcpdump/blob - print-ahcp.c

   1 /*
   2  * This module implements decoding of AHCP (Ad Hoc Configuration Protocol) based
   3  * on draft-chroboczek-ahcp-00 and source code of ahcpd-0.53.
   4  *
   5  *
   6  * Copyright (c) 2013 The TCPDUMP project
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  22  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  26  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  28  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #define NETDISSECT_REWORKED
  33 #ifdef HAVE_CONFIG_H
  34 #include "config.h"
  35 #endif
  36
  37 #include <tcpdump-stdinc.h>
  38
  39 #include "interface.h"
  40 #include "extract.h"
  41 #include "addrtoname.h"
  42
  43 static const char tstr[] = " [|ahcp]";
  44 static const char cstr[] = "(corrupt)";
  45
  46 #define AHCP_MAGIC_NUMBER 43
  47 #define AHCP_VERSION_1 1
  48 #define AHCP1_HEADER_FIX_LEN 24
  49 #define AHCP1_BODY_MIN_LEN 4
  50
  51 #define AHCP1_MSG_DISCOVER 0
  52 #define AHCP1_MSG_OFFER    1
  53 #define AHCP1_MSG_REQUEST  2
  54 #define AHCP1_MSG_ACK      3
  55 #define AHCP1_MSG_NACK     4
  56 #define AHCP1_MSG_RELEASE  5
  57
  58 static const struct tok ahcp1_msg_str[] = {
  59         { AHCP1_MSG_DISCOVER, "Discover" },
  60         { AHCP1_MSG_OFFER,    "Offer"    },
  61         { AHCP1_MSG_REQUEST,  "Request"  },
  62         { AHCP1_MSG_ACK,      "Ack"      },
  63         { AHCP1_MSG_NACK,     "Nack"     },
  64         { AHCP1_MSG_RELEASE,  "Release"  },
  65         { 0, NULL }
  66 };
  67
  68 #define AHCP1_OPT_PAD                     0
  69 #define AHCP1_OPT_MANDATORY               1
  70 #define AHCP1_OPT_ORIGIN_TIME             2
  71 #define AHCP1_OPT_EXPIRES                 3
  72 #define AHCP1_OPT_MY_IPV6_ADDRESS         4
  73 #define AHCP1_OPT_MY_IPV4_ADDRESS         5
  74 #define AHCP1_OPT_IPV6_PREFIX             6
  75 #define AHCP1_OPT_IPV4_PREFIX             7
  76 #define AHCP1_OPT_IPV6_ADDRESS            8
  77 #define AHCP1_OPT_IPV4_ADDRESS            9
  78 #define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
  79 #define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
  80 #define AHCP1_OPT_NAME_SERVER            12
  81 #define AHCP1_OPT_NTP_SERVER             13
  82 #define AHCP1_OPT_MAX                    13
  83
  84 static const struct tok ahcp1_opt_str[] = {
  85         { AHCP1_OPT_PAD,                    "Pad"                    },
  86         { AHCP1_OPT_MANDATORY,              "Mandatory"              },
  87         { AHCP1_OPT_ORIGIN_TIME,            "Origin Time"            },
  88         { AHCP1_OPT_EXPIRES,                "Expires"                },
  89         { AHCP1_OPT_MY_IPV6_ADDRESS,        "My-IPv6-Address"        },
  90         { AHCP1_OPT_MY_IPV4_ADDRESS,        "My-IPv4-Address"        },
  91         { AHCP1_OPT_IPV6_PREFIX,            "IPv6 Prefix"            },
  92         { AHCP1_OPT_IPV4_PREFIX,            "IPv4 Prefix"            },
  93         { AHCP1_OPT_IPV6_ADDRESS,           "IPv6 Address"           },
  94         { AHCP1_OPT_IPV4_ADDRESS,           "IPv4 Address"           },
  95         { AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
  96         { AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
  97         { AHCP1_OPT_NAME_SERVER,            "Name Server"            },
  98         { AHCP1_OPT_NTP_SERVER,             "NTP Server"             },
  99         { 0, NULL }
 100 };
 101
 102 static int
 103 ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 104         time_t t;
 105         struct tm *tm;
 106         char buf[BUFSIZE];
 107
 108         if (cp + 4 != ep)
 109                 goto corrupt;
 110         ND_TCHECK2(*cp, 4);
 111         t = EXTRACT_32BITS(cp);
 112         if (NULL == (tm = gmtime(&t)))
 113                 ND_PRINT((ndo, ": gmtime() error"));
 114         else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
 115                 ND_PRINT((ndo, ": strftime() error"));
 116         else
 117                 ND_PRINT((ndo, ": %s UTC", buf));
 118         return 0;
 119
 120 corrupt:
 121         ND_PRINT((ndo, ": %s", cstr));
 122         ND_TCHECK2(*cp, ep - cp);
 123         return 0;
 124 trunc:
 125         ND_PRINT((ndo, "%s", tstr));
 126         return -1;
 127 }
 128
 129 static int
 130 ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 131         if (cp + 4 != ep)
 132                 goto corrupt;
 133         ND_TCHECK2(*cp, 4);
 134         ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
 135         return 0;
 136
 137 corrupt:
 138         ND_PRINT((ndo, ": %s", cstr));
 139         ND_TCHECK2(*cp, ep - cp);
 140         return 0;
 141 trunc:
 142         ND_PRINT((ndo, "%s", tstr));
 143         return -1;
 144 }
 145
 146 static int
 147 ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 148         const char *sep = ": ";
 149
 150         while (cp < ep) {
 151                 if (cp + 16 > ep)
 152                         goto corrupt;
 153                 ND_TCHECK2(*cp, 16);
 154 #ifdef INET6
 155                 ND_PRINT((ndo, "%s%s", sep, ip6addr_string(cp)));
 156 #else
 157                 ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
 158 #endif /* INET6 */
 159                 cp += 16;
 160                 sep = ", ";
 161         }
 162         return 0;
 163
 164 corrupt:
 165         ND_PRINT((ndo, ": %s", cstr));
 166         ND_TCHECK2(*cp, ep - cp);
 167         return 0;
 168 trunc:
 169         ND_PRINT((ndo, "%s", tstr));
 170         return -1;
 171 }
 172
 173 static int
 174 ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 175         const char *sep = ": ";
 176
 177         while (cp < ep) {
 178                 if (cp + 4 > ep)
 179                         goto corrupt;
 180                 ND_TCHECK2(*cp, 4);
 181                 ND_PRINT((ndo, "%s%s", sep, ipaddr_string(cp)));
 182                 cp += 4;
 183                 sep = ", ";
 184         }
 185         return 0;
 186
 187 corrupt:
 188         ND_PRINT((ndo, ": %s", cstr));
 189         ND_TCHECK2(*cp, ep - cp);
 190         return 0;
 191 trunc:
 192         ND_PRINT((ndo, "%s", tstr));
 193         return -1;
 194 }
 195
 196 static int
 197 ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 198         const char *sep = ": ";
 199
 200         while (cp < ep) {
 201                 if (cp + 17 > ep)
 202                         goto corrupt;
 203                 ND_TCHECK2(*cp, 17);
 204 #ifdef INET6
 205                 ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(cp), *(cp + 16)));
 206 #else
 207                 ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
 208 #endif /* INET6 */
 209                 cp += 17;
 210                 sep = ", ";
 211         }
 212         return 0;
 213
 214 corrupt:
 215         ND_PRINT((ndo, ": %s", cstr));
 216         ND_TCHECK2(*cp, ep - cp);
 217         return 0;
 218 trunc:
 219         ND_PRINT((ndo, "%s", tstr));
 220         return -1;
 221 }
 222
 223 static int
 224 ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 225         const char *sep = ": ";
 226
 227         while (cp < ep) {
 228                 if (cp + 5 > ep)
 229                         goto corrupt;
 230                 ND_TCHECK2(*cp, 5);
 231                 ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(cp), *(cp + 4)));
 232                 cp += 5;
 233                 sep = ", ";
 234         }
 235         return 0;
 236
 237 corrupt:
 238         ND_PRINT((ndo, ": %s", cstr));
 239         ND_TCHECK2(*cp, ep - cp);
 240         return 0;
 241 trunc:
 242         ND_PRINT((ndo, "%s", tstr));
 243         return -1;
 244 }
 245
 246 /* Data decoders signal truncated data with -1. */
 247 static int
 248 (* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
 249         /* [AHCP1_OPT_PAD]                    = */  NULL,
 250         /* [AHCP1_OPT_MANDATORY]              = */  NULL,
 251         /* [AHCP1_OPT_ORIGIN_TIME]            = */  ahcp_time_print,
 252         /* [AHCP1_OPT_EXPIRES]                = */  ahcp_seconds_print,
 253         /* [AHCP1_OPT_MY_IPV6_ADDRESS]        = */  ahcp_ipv6_addresses_print,
 254         /* [AHCP1_OPT_MY_IPV4_ADDRESS]        = */  ahcp_ipv4_addresses_print,
 255         /* [AHCP1_OPT_IPV6_PREFIX]            = */  ahcp_ipv6_prefixes_print,
 256         /* [AHCP1_OPT_IPV4_PREFIX]            = */  NULL,
 257         /* [AHCP1_OPT_IPV6_ADDRESS]           = */  ahcp_ipv6_addresses_print,
 258         /* [AHCP1_OPT_IPV4_ADDRESS]           = */  ahcp_ipv4_addresses_print,
 259         /* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */  ahcp_ipv6_prefixes_print,
 260         /* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */  ahcp_ipv4_prefixes_print,
 261         /* [AHCP1_OPT_NAME_SERVER]            = */  ahcp_ipv6_addresses_print,
 262         /* [AHCP1_OPT_NTP_SERVER]             = */  ahcp_ipv6_addresses_print,
 263 };
 264
 265 static void
 266 ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 267         uint8_t option_no, option_len;
 268
 269         while (cp < ep) {
 270                 /* Option no */
 271                 ND_TCHECK2(*cp, 1);
 272                 option_no = *cp;
 273                 cp += 1;
 274                 ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
 275                 if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
 276                         continue;
 277                 /* Length */
 278                 if (cp + 1 > ep)
 279                         goto corrupt;
 280                 ND_TCHECK2(*cp, 1);
 281                 option_len = *cp;
 282                 cp += 1;
 283                 if (cp + option_len > ep)
 284                         goto corrupt;
 285                 /* Value */
 286                 if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
 287                         if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
 288                                 break; /* truncated and already marked up */
 289                 } else {
 290                         ND_PRINT((ndo, " (Length %u)", option_len));
 291                         ND_TCHECK2(*cp, option_len);
 292                 }
 293                 cp += option_len;
 294         }
 295         return;
 296
 297 corrupt:
 298         ND_PRINT((ndo, " %s", cstr));
 299         ND_TCHECK2(*cp, ep - cp);
 300         return;
 301 trunc:
 302         ND_PRINT((ndo, "%s", tstr));
 303 }
 304
 305 static void
 306 ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 307         uint8_t type, mbz;
 308         uint16_t body_len;
 309
 310         if (cp + AHCP1_BODY_MIN_LEN > ep)
 311                 goto corrupt;
 312         /* Type */
 313         ND_TCHECK2(*cp, 1);
 314         type = *cp;
 315         cp += 1;
 316         /* MBZ */
 317         ND_TCHECK2(*cp, 1);
 318         mbz = *cp;
 319         cp += 1;
 320         /* Length */
 321         ND_TCHECK2(*cp, 2);
 322         body_len = EXTRACT_16BITS(cp);
 323         cp += 2;
 324
 325         if (ndo->ndo_vflag) {
 326                 ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
 327                 if (mbz != 0)
 328                         ND_PRINT((ndo, ", MBZ %u", mbz));
 329                 ND_PRINT((ndo, ", Length %u", body_len));
 330         }
 331         if (cp + body_len > ep)
 332                 goto corrupt;
 333
 334         /* Options */
 335         if (ndo->ndo_vflag >= 2)
 336                 ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
 337         else
 338                 ND_TCHECK2(*cp, body_len);
 339         return;
 340
 341 corrupt:
 342         ND_PRINT((ndo, " %s", cstr));
 343         ND_TCHECK2(*cp, ep - cp);
 344         return;
 345 trunc:
 346         ND_PRINT((ndo, "%s", tstr));
 347 }
 348
 349 void
 350 ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len) {
 351         const u_char *ep = cp + len;
 352         uint8_t version;
 353
 354         ND_PRINT((ndo, "AHCP"));
 355         if (len < 2)
 356                 goto corrupt;
 357         /* Magic */
 358         ND_TCHECK2(*cp, 1);
 359         if (*cp != AHCP_MAGIC_NUMBER)
 360                 goto corrupt;
 361         cp += 1;
 362         /* Version */
 363         ND_TCHECK2(*cp, 1);
 364         version = *cp;
 365         cp += 1;
 366         switch (version) {
 367                 case AHCP_VERSION_1: {
 368                         ND_PRINT((ndo, " Version 1"));
 369                         if (len < AHCP1_HEADER_FIX_LEN)
 370                                 goto corrupt;
 371                         if (!ndo->ndo_vflag) {
 372                                 ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
 373                                 cp += AHCP1_HEADER_FIX_LEN - 2;
 374                         } else {
 375                                 /* Hopcount */
 376                                 ND_TCHECK2(*cp, 1);
 377                                 ND_PRINT((ndo, "\n\tHopcount %u", *cp));
 378                                 cp += 1;
 379                                 /* Original Hopcount */
 380                                 ND_TCHECK2(*cp, 1);
 381                                 ND_PRINT((ndo, ", Original Hopcount %u", *cp));
 382                                 cp += 1;
 383                                 /* Nonce */
 384                                 ND_TCHECK2(*cp, 4);
 385                                 ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
 386                                 cp += 4;
 387                                 /* Source Id */
 388                                 ND_TCHECK2(*cp, 8);
 389                                 ND_PRINT((ndo, ", Source Id %s", linkaddr_string(cp, 0, 8)));
 390                                 cp += 8;
 391                                 /* Destination Id */
 392                                 ND_TCHECK2(*cp, 8);
 393                                 ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(cp, 0, 8)));
 394                                 cp += 8;
 395                         }
 396                         /* Body */
 397                         ahcp1_body_print(ndo, cp, ep);
 398                         break;
 399                 }
 400                 default:
 401                         ND_PRINT((ndo, " Version %u (unknown)", version));
 402                         break;
 403         }
 404         return;
 405
 406 corrupt:
 407         ND_PRINT((ndo, " %s", cstr));
 408         ND_TCHECK2(*cp, ep - cp);
 409         return;
 410 trunc:
 411         ND_PRINT((ndo, "%s", tstr));
 412 }
 413