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 <netdissect-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 istr[] = " (invalid)";
  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 {
 104         time_t t;
 105         struct tm *tm;
 106         char buf[BUFSIZE];
 107
 108         if (cp + 4 != ep)
 109                 goto invalid;
 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 invalid:
 121         ND_PRINT((ndo, "%s", istr));
 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 {
 132         if (cp + 4 != ep)
 133                 goto invalid;
 134         ND_TCHECK2(*cp, 4);
 135         ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
 136         return 0;
 137
 138 invalid:
 139         ND_PRINT((ndo, "%s", istr));
 140         ND_TCHECK2(*cp, ep - cp);
 141         return 0;
 142 trunc:
 143         ND_PRINT((ndo, "%s", tstr));
 144         return -1;
 145 }
 146
 147 static int
 148 ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 149 {
 150         const char *sep = ": ";
 151
 152         while (cp < ep) {
 153                 if (cp + 16 > ep)
 154                         goto invalid;
 155                 ND_TCHECK2(*cp, 16);
 156                 ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
 157                 cp += 16;
 158                 sep = ", ";
 159         }
 160         return 0;
 161
 162 invalid:
 163         ND_PRINT((ndo, "%s", istr));
 164         ND_TCHECK2(*cp, ep - cp);
 165         return 0;
 166 trunc:
 167         ND_PRINT((ndo, "%s", tstr));
 168         return -1;
 169 }
 170
 171 static int
 172 ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 173 {
 174         const char *sep = ": ";
 175
 176         while (cp < ep) {
 177                 if (cp + 4 > ep)
 178                         goto invalid;
 179                 ND_TCHECK2(*cp, 4);
 180                 ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
 181                 cp += 4;
 182                 sep = ", ";
 183         }
 184         return 0;
 185
 186 invalid:
 187         ND_PRINT((ndo, "%s", istr));
 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 {
 198         const char *sep = ": ";
 199
 200         while (cp < ep) {
 201                 if (cp + 17 > ep)
 202                         goto invalid;
 203                 ND_TCHECK2(*cp, 17);
 204                 ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
 205                 cp += 17;
 206                 sep = ", ";
 207         }
 208         return 0;
 209
 210 invalid:
 211         ND_PRINT((ndo, "%s", istr));
 212         ND_TCHECK2(*cp, ep - cp);
 213         return 0;
 214 trunc:
 215         ND_PRINT((ndo, "%s", tstr));
 216         return -1;
 217 }
 218
 219 static int
 220 ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 221 {
 222         const char *sep = ": ";
 223
 224         while (cp < ep) {
 225                 if (cp + 5 > ep)
 226                         goto invalid;
 227                 ND_TCHECK2(*cp, 5);
 228                 ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
 229                 cp += 5;
 230                 sep = ", ";
 231         }
 232         return 0;
 233
 234 invalid:
 235         ND_PRINT((ndo, "%s", istr));
 236         ND_TCHECK2(*cp, ep - cp);
 237         return 0;
 238 trunc:
 239         ND_PRINT((ndo, "%s", tstr));
 240         return -1;
 241 }
 242
 243 /* Data decoders signal truncated data with -1. */
 244 static int
 245 (* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
 246         /* [AHCP1_OPT_PAD]                    = */  NULL,
 247         /* [AHCP1_OPT_MANDATORY]              = */  NULL,
 248         /* [AHCP1_OPT_ORIGIN_TIME]            = */  ahcp_time_print,
 249         /* [AHCP1_OPT_EXPIRES]                = */  ahcp_seconds_print,
 250         /* [AHCP1_OPT_MY_IPV6_ADDRESS]        = */  ahcp_ipv6_addresses_print,
 251         /* [AHCP1_OPT_MY_IPV4_ADDRESS]        = */  ahcp_ipv4_addresses_print,
 252         /* [AHCP1_OPT_IPV6_PREFIX]            = */  ahcp_ipv6_prefixes_print,
 253         /* [AHCP1_OPT_IPV4_PREFIX]            = */  NULL,
 254         /* [AHCP1_OPT_IPV6_ADDRESS]           = */  ahcp_ipv6_addresses_print,
 255         /* [AHCP1_OPT_IPV4_ADDRESS]           = */  ahcp_ipv4_addresses_print,
 256         /* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */  ahcp_ipv6_prefixes_print,
 257         /* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */  ahcp_ipv4_prefixes_print,
 258         /* [AHCP1_OPT_NAME_SERVER]            = */  ahcp_ipv6_addresses_print,
 259         /* [AHCP1_OPT_NTP_SERVER]             = */  ahcp_ipv6_addresses_print,
 260 };
 261
 262 static void
 263 ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 264 {
 265         uint8_t option_no, option_len;
 266
 267         while (cp < ep) {
 268                 /* Option no */
 269                 ND_TCHECK2(*cp, 1);
 270                 option_no = *cp;
 271                 cp += 1;
 272                 ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
 273                 if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
 274                         continue;
 275                 /* Length */
 276                 if (cp + 1 > ep)
 277                         goto invalid;
 278                 ND_TCHECK2(*cp, 1);
 279                 option_len = *cp;
 280                 cp += 1;
 281                 if (cp + option_len > ep)
 282                         goto invalid;
 283                 /* Value */
 284                 if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
 285                         if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
 286                                 break; /* truncated and already marked up */
 287                 } else {
 288                         ND_PRINT((ndo, " (Length %u)", option_len));
 289                         ND_TCHECK2(*cp, option_len);
 290                 }
 291                 cp += option_len;
 292         }
 293         return;
 294
 295 invalid:
 296         ND_PRINT((ndo, "%s", istr));
 297         ND_TCHECK2(*cp, ep - cp);
 298         return;
 299 trunc:
 300         ND_PRINT((ndo, "%s", tstr));
 301 }
 302
 303 static void
 304 ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 305 {
 306         uint8_t type, mbz;
 307         uint16_t body_len;
 308
 309         if (cp + AHCP1_BODY_MIN_LEN > ep)
 310                 goto invalid;
 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 invalid;
 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 invalid:
 341         ND_PRINT((ndo, "%s", istr));
 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 {
 351         const u_char *ep = cp + len;
 352         uint8_t version;
 353
 354         ND_PRINT((ndo, "AHCP"));
 355         if (len < 2)
 356                 goto invalid;
 357         /* Magic */
 358         ND_TCHECK2(*cp, 1);
 359         if (*cp != AHCP_MAGIC_NUMBER)
 360                 goto invalid;
 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 invalid;
 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(ndo, cp, 0, 8)));
 390                                 cp += 8;
 391                                 /* Destination Id */
 392                                 ND_TCHECK2(*cp, 8);
 393                                 ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, 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 invalid:
 407         ND_PRINT((ndo, "%s", istr));
 408         ND_TCHECK2(*cp, ep - cp);
 409         return;
 410 trunc:
 411         ND_PRINT((ndo, "%s", tstr));
 412 }