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 #ifdef HAVE_CONFIG_H
  33 #include "config.h"
  34 #endif
  35
  36 #include <tcpdump-stdinc.h>
  37
  38 #include "netdissect.h"
  39 #include "extract.h"
  40 #include "addrtoname.h"
  41
  42 static const char tstr[] = " [|ahcp]";
  43 static const char cstr[] = "(corrupt)";
  44
  45 #define AHCP_MAGIC_NUMBER 43
  46 #define AHCP_VERSION_1 1
  47 #define AHCP1_HEADER_FIX_LEN 24
  48 #define AHCP1_BODY_MIN_LEN 4
  49
  50 #define AHCP1_MSG_DISCOVER 0
  51 #define AHCP1_MSG_OFFER    1
  52 #define AHCP1_MSG_REQUEST  2
  53 #define AHCP1_MSG_ACK      3
  54 #define AHCP1_MSG_NACK     4
  55 #define AHCP1_MSG_RELEASE  5
  56
  57 static const struct tok ahcp1_msg_str[] = {
  58         { AHCP1_MSG_DISCOVER, "Discover" },
  59         { AHCP1_MSG_OFFER,    "Offer"    },
  60         { AHCP1_MSG_REQUEST,  "Request"  },
  61         { AHCP1_MSG_ACK,      "Ack"      },
  62         { AHCP1_MSG_NACK,     "Nack"     },
  63         { AHCP1_MSG_RELEASE,  "Release"  },
  64         { 0, NULL }
  65 };
  66
  67 #define AHCP1_OPT_PAD                     0
  68 #define AHCP1_OPT_MANDATORY               1
  69 #define AHCP1_OPT_ORIGIN_TIME             2
  70 #define AHCP1_OPT_EXPIRES                 3
  71 #define AHCP1_OPT_MY_IPV6_ADDRESS         4
  72 #define AHCP1_OPT_MY_IPV4_ADDRESS         5
  73 #define AHCP1_OPT_IPV6_PREFIX             6
  74 #define AHCP1_OPT_IPV4_PREFIX             7
  75 #define AHCP1_OPT_IPV6_ADDRESS            8
  76 #define AHCP1_OPT_IPV4_ADDRESS            9
  77 #define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
  78 #define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
  79 #define AHCP1_OPT_NAME_SERVER            12
  80 #define AHCP1_OPT_NTP_SERVER             13
  81 #define AHCP1_OPT_MAX                    13
  82
  83 static const struct tok ahcp1_opt_str[] = {
  84         { AHCP1_OPT_PAD,                    "Pad"                    },
  85         { AHCP1_OPT_MANDATORY,              "Mandatory"              },
  86         { AHCP1_OPT_ORIGIN_TIME,            "Origin Time"            },
  87         { AHCP1_OPT_EXPIRES,                "Expires"                },
  88         { AHCP1_OPT_MY_IPV6_ADDRESS,        "My-IPv6-Address"        },
  89         { AHCP1_OPT_MY_IPV4_ADDRESS,        "My-IPv4-Address"        },
  90         { AHCP1_OPT_IPV6_PREFIX,            "IPv6 Prefix"            },
  91         { AHCP1_OPT_IPV4_PREFIX,            "IPv4 Prefix"            },
  92         { AHCP1_OPT_IPV6_ADDRESS,           "IPv6 Address"           },
  93         { AHCP1_OPT_IPV4_ADDRESS,           "IPv4 Address"           },
  94         { AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
  95         { AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
  96         { AHCP1_OPT_NAME_SERVER,            "Name Server"            },
  97         { AHCP1_OPT_NTP_SERVER,             "NTP Server"             },
  98         { 0, NULL }
  99 };
 100
 101 static int
 102 ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 103         time_t t;
 104         struct tm *tm;
 105         char buf[BUFSIZE];
 106
 107         if (cp + 4 != ep)
 108                 goto corrupt;
 109         ND_TCHECK2(*cp, 4);
 110         t = EXTRACT_32BITS(cp);
 111         if (NULL == (tm = gmtime(&t)))
 112                 ND_PRINT((ndo, ": gmtime() error"));
 113         else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
 114                 ND_PRINT((ndo, ": strftime() error"));
 115         else
 116                 ND_PRINT((ndo, ": %s UTC", buf));
 117         return 0;
 118
 119 corrupt:
 120         ND_PRINT((ndo, ": %s", cstr));
 121         ND_TCHECK2(*cp, ep - cp);
 122         return 0;
 123 trunc:
 124         ND_PRINT((ndo, "%s", tstr));
 125         return -1;
 126 }
 127
 128 static int
 129 ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 130         if (cp + 4 != ep)
 131                 goto corrupt;
 132         ND_TCHECK2(*cp, 4);
 133         ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
 134         return 0;
 135
 136 corrupt:
 137         ND_PRINT((ndo, ": %s", cstr));
 138         ND_TCHECK2(*cp, ep - cp);
 139         return 0;
 140 trunc:
 141         ND_PRINT((ndo, "%s", tstr));
 142         return -1;
 143 }
 144
 145 static int
 146 ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 147         const char *sep = ": ";
 148
 149         while (cp < ep) {
 150                 if (cp + 16 > ep)
 151                         goto corrupt;
 152                 ND_TCHECK2(*cp, 16);
 153 #ifdef INET6
 154                 ND_PRINT((ndo, "%s%s", sep, ip6addr_string(cp)));
 155 #else
 156                 ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
 157 #endif /* INET6 */
 158                 cp += 16;
 159                 sep = ", ";
 160         }
 161         return 0;
 162
 163 corrupt:
 164         ND_PRINT((ndo, ": %s", cstr));
 165         ND_TCHECK2(*cp, ep - cp);
 166         return 0;
 167 trunc:
 168         ND_PRINT((ndo, "%s", tstr));
 169         return -1;
 170 }
 171
 172 static int
 173 ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 174         const char *sep = ": ";
 175
 176         while (cp < ep) {
 177                 if (cp + 4 > ep)
 178                         goto corrupt;
 179                 ND_TCHECK2(*cp, 4);
 180                 ND_PRINT((ndo, "%s%s", sep, ipaddr_string(cp)));
 181                 cp += 4;
 182                 sep = ", ";
 183         }
 184         return 0;
 185
 186 corrupt:
 187         ND_PRINT((ndo, ": %s", cstr));
 188         ND_TCHECK2(*cp, ep - cp);
 189         return 0;
 190 trunc:
 191         ND_PRINT((ndo, "%s", tstr));
 192         return -1;
 193 }
 194
 195 static int
 196 ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 197         const char *sep = ": ";
 198
 199         while (cp < ep) {
 200                 if (cp + 17 > ep)
 201                         goto corrupt;
 202                 ND_TCHECK2(*cp, 17);
 203 #ifdef INET6
 204                 ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(cp), *(cp + 16)));
 205 #else
 206                 ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
 207 #endif /* INET6 */
 208                 cp += 17;
 209                 sep = ", ";
 210         }
 211         return 0;
 212
 213 corrupt:
 214         ND_PRINT((ndo, ": %s", cstr));
 215         ND_TCHECK2(*cp, ep - cp);
 216         return 0;
 217 trunc:
 218         ND_PRINT((ndo, "%s", tstr));
 219         return -1;
 220 }
 221
 222 static int
 223 ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 224         const char *sep = ": ";
 225
 226         while (cp < ep) {
 227                 if (cp + 5 > ep)
 228                         goto corrupt;
 229                 ND_TCHECK2(*cp, 5);
 230                 ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(cp), *(cp + 4)));
 231                 cp += 5;
 232                 sep = ", ";
 233         }
 234         return 0;
 235
 236 corrupt:
 237         ND_PRINT((ndo, ": %s", cstr));
 238         ND_TCHECK2(*cp, ep - cp);
 239         return 0;
 240 trunc:
 241         ND_PRINT((ndo, "%s", tstr));
 242         return -1;
 243 }
 244
 245 /* Data decoders signal truncated data with -1. */
 246 static int
 247 (* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
 248         /* [AHCP1_OPT_PAD]                    = */  NULL,
 249         /* [AHCP1_OPT_MANDATORY]              = */  NULL,
 250         /* [AHCP1_OPT_ORIGIN_TIME]            = */  ahcp_time_print,
 251         /* [AHCP1_OPT_EXPIRES]                = */  ahcp_seconds_print,
 252         /* [AHCP1_OPT_MY_IPV6_ADDRESS]        = */  ahcp_ipv6_addresses_print,
 253         /* [AHCP1_OPT_MY_IPV4_ADDRESS]        = */  ahcp_ipv4_addresses_print,
 254         /* [AHCP1_OPT_IPV6_PREFIX]            = */  ahcp_ipv6_prefixes_print,
 255         /* [AHCP1_OPT_IPV4_PREFIX]            = */  NULL,
 256         /* [AHCP1_OPT_IPV6_ADDRESS]           = */  ahcp_ipv6_addresses_print,
 257         /* [AHCP1_OPT_IPV4_ADDRESS]           = */  ahcp_ipv4_addresses_print,
 258         /* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */  ahcp_ipv6_prefixes_print,
 259         /* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */  ahcp_ipv4_prefixes_print,
 260         /* [AHCP1_OPT_NAME_SERVER]            = */  ahcp_ipv6_addresses_print,
 261         /* [AHCP1_OPT_NTP_SERVER]             = */  ahcp_ipv6_addresses_print,
 262 };
 263
 264 static void
 265 ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 266         uint8_t option_no, option_len;
 267
 268         while (cp < ep) {
 269                 /* Option no */
 270                 ND_TCHECK2(*cp, 1);
 271                 option_no = *cp;
 272                 cp += 1;
 273                 ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
 274                 if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
 275                         continue;
 276                 /* Length */
 277                 if (cp + 1 > ep)
 278                         goto corrupt;
 279                 ND_TCHECK2(*cp, 1);
 280                 option_len = *cp;
 281                 cp += 1;
 282                 if (cp + option_len > ep)
 283                         goto corrupt;
 284                 /* Value */
 285                 if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
 286                         if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
 287                                 break; /* truncated and already marked up */
 288                 } else {
 289                         ND_PRINT((ndo, " (Length %u)", option_len));
 290                         ND_TCHECK2(*cp, option_len);
 291                 }
 292                 cp += option_len;
 293         }
 294         return;
 295
 296 corrupt:
 297         ND_PRINT((ndo, " %s", cstr));
 298         ND_TCHECK2(*cp, ep - cp);
 299         return;
 300 trunc:
 301         ND_PRINT((ndo, "%s", tstr));
 302 }
 303
 304 static void
 305 ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
 306         uint8_t type, mbz;
 307         uint16_t body_len;
 308
 309         if (cp + AHCP1_BODY_MIN_LEN > ep)
 310                 goto corrupt;
 311         /* Type */
 312         ND_TCHECK2(*cp, 1);
 313         type = *cp;
 314         cp += 1;
 315         /* MBZ */
 316         ND_TCHECK2(*cp, 1);
 317         mbz = *cp;
 318         cp += 1;
 319         /* Length */
 320         ND_TCHECK2(*cp, 2);
 321         body_len = EXTRACT_16BITS(cp);
 322         cp += 2;
 323
 324         if (ndo->ndo_vflag) {
 325                 ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
 326                 if (mbz != 0)
 327                         ND_PRINT((ndo, ", MBZ %u", mbz));
 328                 ND_PRINT((ndo, ", Length %u", body_len));
 329         }
 330         if (cp + body_len > ep)
 331                 goto corrupt;
 332
 333         /* Options */
 334         if (ndo->ndo_vflag >= 2)
 335                 ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
 336         else
 337                 ND_TCHECK2(*cp, body_len);
 338         return;
 339
 340 corrupt:
 341         ND_PRINT((ndo, " %s", cstr));
 342         ND_TCHECK2(*cp, ep - cp);
 343         return;
 344 trunc:
 345         ND_PRINT((ndo, "%s", tstr));
 346 }
 347
 348 void
 349 ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len) {
 350         const u_char *ep = cp + len;
 351         uint8_t version;
 352
 353         ND_PRINT((ndo, "AHCP"));
 354         if (len < 2)
 355                 goto corrupt;
 356         /* Magic */
 357         ND_TCHECK2(*cp, 1);
 358         if (*cp != AHCP_MAGIC_NUMBER)
 359                 goto corrupt;
 360         cp += 1;
 361         /* Version */
 362         ND_TCHECK2(*cp, 1);
 363         version = *cp;
 364         cp += 1;
 365         switch (version) {
 366                 case AHCP_VERSION_1: {
 367                         ND_PRINT((ndo, " Version 1"));
 368                         if (len < AHCP1_HEADER_FIX_LEN)
 369                                 goto corrupt;
 370                         if (!ndo->ndo_vflag) {
 371                                 ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
 372                                 cp += AHCP1_HEADER_FIX_LEN - 2;
 373                         } else {
 374                                 /* Hopcount */
 375                                 ND_TCHECK2(*cp, 1);
 376                                 ND_PRINT((ndo, "\n\tHopcount %u", *cp));
 377                                 cp += 1;
 378                                 /* Original Hopcount */
 379                                 ND_TCHECK2(*cp, 1);
 380                                 ND_PRINT((ndo, ", Original Hopcount %u", *cp));
 381                                 cp += 1;
 382                                 /* Nonce */
 383                                 ND_TCHECK2(*cp, 4);
 384                                 ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
 385                                 cp += 4;
 386                                 /* Source Id */
 387                                 ND_TCHECK2(*cp, 8);
 388                                 ND_PRINT((ndo, ", Source Id %s", linkaddr_string(cp, 0, 8)));
 389                                 cp += 8;
 390                                 /* Destination Id */
 391                                 ND_TCHECK2(*cp, 8);
 392                                 ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(cp, 0, 8)));
 393                                 cp += 8;
 394                         }
 395                         /* Body */
 396                         ahcp1_body_print(ndo, cp, ep);
 397                         break;
 398                 }
 399                 default:
 400                         ND_PRINT((ndo, " Version %u (unknown)", version));
 401                         break;
 402         }
 403         return;
 404
 405 corrupt:
 406         ND_PRINT((ndo, " %s", cstr));
 407         ND_TCHECK2(*cp, ep - cp);
 408         return;
 409 trunc:
 410         ND_PRINT((ndo, "%s", tstr));
 411 }
 412