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 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 #ifdef INET6
 157                 ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
 158 #else
 159                 ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
 160 #endif /* INET6 */
 161                 cp += 16;
 162                 sep = ", ";
 163         }
 164         return 0;
 165
 166 invalid:
 167         ND_PRINT((ndo, "%s", istr));
 168         ND_TCHECK2(*cp, ep - cp);
 169         return 0;
 170 trunc:
 171         ND_PRINT((ndo, "%s", tstr));
 172         return -1;
 173 }
 174
 175 static int
 176 ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 177 {
 178         const char *sep = ": ";
 179
 180         while (cp < ep) {
 181                 if (cp + 4 > ep)
 182                         goto invalid;
 183                 ND_TCHECK2(*cp, 4);
 184                 ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
 185                 cp += 4;
 186                 sep = ", ";
 187         }
 188         return 0;
 189
 190 invalid:
 191         ND_PRINT((ndo, "%s", istr));
 192         ND_TCHECK2(*cp, ep - cp);
 193         return 0;
 194 trunc:
 195         ND_PRINT((ndo, "%s", tstr));
 196         return -1;
 197 }
 198
 199 static int
 200 ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 201 {
 202         const char *sep = ": ";
 203
 204         while (cp < ep) {
 205                 if (cp + 17 > ep)
 206                         goto invalid;
 207                 ND_TCHECK2(*cp, 17);
 208 #ifdef INET6
 209                 ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
 210 #else
 211                 ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
 212 #endif /* INET6 */
 213                 cp += 17;
 214                 sep = ", ";
 215         }
 216         return 0;
 217
 218 invalid:
 219         ND_PRINT((ndo, "%s", istr));
 220         ND_TCHECK2(*cp, ep - cp);
 221         return 0;
 222 trunc:
 223         ND_PRINT((ndo, "%s", tstr));
 224         return -1;
 225 }
 226
 227 static int
 228 ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 229 {
 230         const char *sep = ": ";
 231
 232         while (cp < ep) {
 233                 if (cp + 5 > ep)
 234                         goto invalid;
 235                 ND_TCHECK2(*cp, 5);
 236                 ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
 237                 cp += 5;
 238                 sep = ", ";
 239         }
 240         return 0;
 241
 242 invalid:
 243         ND_PRINT((ndo, "%s", istr));
 244         ND_TCHECK2(*cp, ep - cp);
 245         return 0;
 246 trunc:
 247         ND_PRINT((ndo, "%s", tstr));
 248         return -1;
 249 }
 250
 251 /* Data decoders signal truncated data with -1. */
 252 static int
 253 (* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
 254         /* [AHCP1_OPT_PAD]                    = */  NULL,
 255         /* [AHCP1_OPT_MANDATORY]              = */  NULL,
 256         /* [AHCP1_OPT_ORIGIN_TIME]            = */  ahcp_time_print,
 257         /* [AHCP1_OPT_EXPIRES]                = */  ahcp_seconds_print,
 258         /* [AHCP1_OPT_MY_IPV6_ADDRESS]        = */  ahcp_ipv6_addresses_print,
 259         /* [AHCP1_OPT_MY_IPV4_ADDRESS]        = */  ahcp_ipv4_addresses_print,
 260         /* [AHCP1_OPT_IPV6_PREFIX]            = */  ahcp_ipv6_prefixes_print,
 261         /* [AHCP1_OPT_IPV4_PREFIX]            = */  NULL,
 262         /* [AHCP1_OPT_IPV6_ADDRESS]           = */  ahcp_ipv6_addresses_print,
 263         /* [AHCP1_OPT_IPV4_ADDRESS]           = */  ahcp_ipv4_addresses_print,
 264         /* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */  ahcp_ipv6_prefixes_print,
 265         /* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */  ahcp_ipv4_prefixes_print,
 266         /* [AHCP1_OPT_NAME_SERVER]            = */  ahcp_ipv6_addresses_print,
 267         /* [AHCP1_OPT_NTP_SERVER]             = */  ahcp_ipv6_addresses_print,
 268 };
 269
 270 static void
 271 ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 272 {
 273         uint8_t option_no, option_len;
 274
 275         while (cp < ep) {
 276                 /* Option no */
 277                 ND_TCHECK2(*cp, 1);
 278                 option_no = *cp;
 279                 cp += 1;
 280                 ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
 281                 if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
 282                         continue;
 283                 /* Length */
 284                 if (cp + 1 > ep)
 285                         goto invalid;
 286                 ND_TCHECK2(*cp, 1);
 287                 option_len = *cp;
 288                 cp += 1;
 289                 if (cp + option_len > ep)
 290                         goto invalid;
 291                 /* Value */
 292                 if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
 293                         if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
 294                                 break; /* truncated and already marked up */
 295                 } else {
 296                         ND_PRINT((ndo, " (Length %u)", option_len));
 297                         ND_TCHECK2(*cp, option_len);
 298                 }
 299                 cp += option_len;
 300         }
 301         return;
 302
 303 invalid:
 304         ND_PRINT((ndo, "%s", istr));
 305         ND_TCHECK2(*cp, ep - cp);
 306         return;
 307 trunc:
 308         ND_PRINT((ndo, "%s", tstr));
 309 }
 310
 311 static void
 312 ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
 313 {
 314         uint8_t type, mbz;
 315         uint16_t body_len;
 316
 317         if (cp + AHCP1_BODY_MIN_LEN > ep)
 318                 goto invalid;
 319         /* Type */
 320         ND_TCHECK2(*cp, 1);
 321         type = *cp;
 322         cp += 1;
 323         /* MBZ */
 324         ND_TCHECK2(*cp, 1);
 325         mbz = *cp;
 326         cp += 1;
 327         /* Length */
 328         ND_TCHECK2(*cp, 2);
 329         body_len = EXTRACT_16BITS(cp);
 330         cp += 2;
 331
 332         if (ndo->ndo_vflag) {
 333                 ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
 334                 if (mbz != 0)
 335                         ND_PRINT((ndo, ", MBZ %u", mbz));
 336                 ND_PRINT((ndo, ", Length %u", body_len));
 337         }
 338         if (cp + body_len > ep)
 339                 goto invalid;
 340
 341         /* Options */
 342         if (ndo->ndo_vflag >= 2)
 343                 ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
 344         else
 345                 ND_TCHECK2(*cp, body_len);
 346         return;
 347
 348 invalid:
 349         ND_PRINT((ndo, "%s", istr));
 350         ND_TCHECK2(*cp, ep - cp);
 351         return;
 352 trunc:
 353         ND_PRINT((ndo, "%s", tstr));
 354 }
 355
 356 void
 357 ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len)
 358 {
 359         const u_char *ep = cp + len;
 360         uint8_t version;
 361
 362         ND_PRINT((ndo, "AHCP"));
 363         if (len < 2)
 364                 goto invalid;
 365         /* Magic */
 366         ND_TCHECK2(*cp, 1);
 367         if (*cp != AHCP_MAGIC_NUMBER)
 368                 goto invalid;
 369         cp += 1;
 370         /* Version */
 371         ND_TCHECK2(*cp, 1);
 372         version = *cp;
 373         cp += 1;
 374         switch (version) {
 375                 case AHCP_VERSION_1: {
 376                         ND_PRINT((ndo, " Version 1"));
 377                         if (len < AHCP1_HEADER_FIX_LEN)
 378                                 goto invalid;
 379                         if (!ndo->ndo_vflag) {
 380                                 ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
 381                                 cp += AHCP1_HEADER_FIX_LEN - 2;
 382                         } else {
 383                                 /* Hopcount */
 384                                 ND_TCHECK2(*cp, 1);
 385                                 ND_PRINT((ndo, "\n\tHopcount %u", *cp));
 386                                 cp += 1;
 387                                 /* Original Hopcount */
 388                                 ND_TCHECK2(*cp, 1);
 389                                 ND_PRINT((ndo, ", Original Hopcount %u", *cp));
 390                                 cp += 1;
 391                                 /* Nonce */
 392                                 ND_TCHECK2(*cp, 4);
 393                                 ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
 394                                 cp += 4;
 395                                 /* Source Id */
 396                                 ND_TCHECK2(*cp, 8);
 397                                 ND_PRINT((ndo, ", Source Id %s", linkaddr_string(ndo, cp, 0, 8)));
 398                                 cp += 8;
 399                                 /* Destination Id */
 400                                 ND_TCHECK2(*cp, 8);
 401                                 ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, cp, 0, 8)));
 402                                 cp += 8;
 403                         }
 404                         /* Body */
 405                         ahcp1_body_print(ndo, cp, ep);
 406                         break;
 407                 }
 408                 default:
 409                         ND_PRINT((ndo, " Version %u (unknown)", version));
 410                         break;
 411         }
 412         return;
 413
 414 invalid:
 415         ND_PRINT((ndo, "%s", istr));
 416         ND_TCHECK2(*cp, ep - cp);
 417         return;
 418 trunc:
 419         ND_PRINT((ndo, "%s", tstr));
 420 }