1/* 2 * Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC") 3 * Copyright (C) 2000, 2001 Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 * PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18/* $Id: lwresutil.c,v 1.34 2007/06/19 23:47:22 tbox Exp $ */ 19 20/*! \file */ 21 22/** 23 * lwres_string_parse() retrieves a DNS-encoded string starting the 24 * current pointer of lightweight resolver buffer b: i.e. b->current. 25 * When the function returns, the address of the first byte of the 26 * encoded string is returned via *c and the length of that string is 27 * given by *len. The buffer's current pointer is advanced to point at 28 * the character following the string length, the encoded string, and 29 * the trailing NULL character. 30 * 31 * lwres_addr_parse() extracts an address from the buffer b. The 32 * buffer's current pointer b->current is presumed to point at an 33 * encoded address: the address preceded by a 32-bit protocol family 34 * identifier and a 16-bit length field. The encoded address is copied 35 * to addr->address and addr->length indicates the size in bytes of 36 * the address that was copied. b->current is advanced to point at the 37 * next byte of available data in the buffer following the encoded 38 * address. 39 * 40 * lwres_getaddrsbyname() and lwres_getnamebyaddr() use the 41 * lwres_gnbaresponse_t structure defined below: 42 * 43 * \code 44 * typedef struct { 45 * lwres_uint32_t flags; 46 * lwres_uint16_t naliases; 47 * lwres_uint16_t naddrs; 48 * char *realname; 49 * char **aliases; 50 * lwres_uint16_t realnamelen; 51 * lwres_uint16_t *aliaslen; 52 * lwres_addrlist_t addrs; 53 * void *base; 54 * size_t baselen; 55 * } lwres_gabnresponse_t; 56 * \endcode 57 * 58 * The contents of this structure are not manipulated directly but 59 * they are controlled through the \link lwres_gabn.c lwres_gabn*\endlink functions. 60 * 61 * The lightweight resolver uses lwres_getaddrsbyname() to perform 62 * foward lookups. Hostname name is looked up using the resolver 63 * context ctx for memory allocation. addrtypes is a bitmask 64 * indicating which type of addresses are to be looked up. Current 65 * values for this bitmask are #LWRES_ADDRTYPE_V4 for IPv4 addresses 66 * and #LWRES_ADDRTYPE_V6 for IPv6 addresses. Results of the lookup are 67 * returned in *structp. 68 * 69 * lwres_getnamebyaddr() performs reverse lookups. Resolver context 70 * ctx is used for memory allocation. The address type is indicated by 71 * addrtype: #LWRES_ADDRTYPE_V4 or #LWRES_ADDRTYPE_V6. The address to be 72 * looked up is given by addr and its length is addrlen bytes. The 73 * result of the function call is made available through *structp. 74 * 75 * \section lwresutil_return Return Values 76 * 77 * Successful calls to lwres_string_parse() and lwres_addr_parse() 78 * return #LWRES_R_SUCCESS. Both functions return #LWRES_R_FAILURE if 79 * the buffer is corrupt or #LWRES_R_UNEXPECTEDEND if the buffer has 80 * less space than expected for the components of the encoded string 81 * or address. 82 * 83 * lwres_getaddrsbyname() returns #LWRES_R_SUCCESS on success and it 84 * returns #LWRES_R_NOTFOUND if the hostname name could not be found. 85 * 86 * #LWRES_R_SUCCESS is returned by a successful call to 87 * lwres_getnamebyaddr(). 88 * 89 * Both lwres_getaddrsbyname() and lwres_getnamebyaddr() return 90 * #LWRES_R_NOMEMORY when memory allocation requests fail and 91 * #LWRES_R_UNEXPECTEDEND if the buffers used for sending queries and 92 * receiving replies are too small. 93 * 94 * \section lwresutil_see See Also 95 * 96 * lwbuffer.c, lwres_gabn.c 97 */ 98 99#include <config.h> 100 101#include <assert.h> 102#include <stdlib.h> 103#include <string.h> 104#include <unistd.h> 105 106#include <lwres/lwbuffer.h> 107#include <lwres/lwres.h> 108#include <lwres/result.h> 109 110#include "assert_p.h" 111#include "context_p.h" 112 113/*% Parse data. */ 114/*! 115 * Requires: 116 * 117 * The "current" pointer in "b" points to encoded raw data. 118 * 119 * Ensures: 120 * 121 * The address of the first byte of the data is returned via "p", 122 * and the length is returned via "len". If NULL, they are not 123 * set. 124 * 125 * On return, the current pointer of "b" will point to the character 126 * following the data length and the data. 127 * 128 */ 129lwres_result_t 130lwres_data_parse(lwres_buffer_t *b, unsigned char **p, lwres_uint16_t *len) 131{ 132 lwres_uint16_t datalen; 133 unsigned char *data; 134 135 REQUIRE(b != NULL); 136 137 /* 138 * Pull off the length (2 bytes) 139 */ 140 if (!SPACE_REMAINING(b, 2)) 141 return (LWRES_R_UNEXPECTEDEND); 142 datalen = lwres_buffer_getuint16(b); 143 144 /* 145 * Set the pointer to this string to the right place, then 146 * advance the buffer pointer. 147 */ 148 if (!SPACE_REMAINING(b, datalen)) 149 return (LWRES_R_UNEXPECTEDEND); 150 data = b->base + b->current; 151 lwres_buffer_forward(b, datalen); 152 153 if (len != NULL) 154 *len = datalen; 155 if (p != NULL) 156 *p = data; 157 158 return (LWRES_R_SUCCESS); 159} 160 161/*% Retrieves a DNS-encoded string. */ 162/*! 163 * Requires: 164 * 165 * The "current" pointer in "b" point to an encoded string. 166 * 167 * Ensures: 168 * 169 * The address of the first byte of the string is returned via "c", 170 * and the length is returned via "len". If NULL, they are not 171 * set. 172 * 173 * On return, the current pointer of "b" will point to the character 174 * following the string length, the string, and the trailing NULL. 175 * 176 */ 177lwres_result_t 178lwres_string_parse(lwres_buffer_t *b, char **c, lwres_uint16_t *len) 179{ 180 lwres_uint16_t datalen; 181 char *string; 182 183 REQUIRE(b != NULL); 184 185 /* 186 * Pull off the length (2 bytes) 187 */ 188 if (!SPACE_REMAINING(b, 2)) 189 return (LWRES_R_UNEXPECTEDEND); 190 datalen = lwres_buffer_getuint16(b); 191 192 /* 193 * Set the pointer to this string to the right place, then 194 * advance the buffer pointer. 195 */ 196 if (!SPACE_REMAINING(b, datalen)) 197 return (LWRES_R_UNEXPECTEDEND); 198 string = (char *)b->base + b->current; 199 lwres_buffer_forward(b, datalen); 200 201 /* 202 * Skip the "must be zero" byte. 203 */ 204 if (!SPACE_REMAINING(b, 1)) 205 return (LWRES_R_UNEXPECTEDEND); 206 if (0 != lwres_buffer_getuint8(b)) 207 return (LWRES_R_FAILURE); 208 209 if (len != NULL) 210 *len = datalen; 211 if (c != NULL) 212 *c = string; 213 214 return (LWRES_R_SUCCESS); 215} 216 217/*% Extracts an address from the buffer b. */ 218lwres_result_t 219lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr) 220{ 221 REQUIRE(addr != NULL); 222 223 if (!SPACE_REMAINING(b, 6)) 224 return (LWRES_R_UNEXPECTEDEND); 225 226 addr->family = lwres_buffer_getuint32(b); 227 addr->length = lwres_buffer_getuint16(b); 228 229 if (!SPACE_REMAINING(b, addr->length)) 230 return (LWRES_R_UNEXPECTEDEND); 231 if (addr->length > LWRES_ADDR_MAXLEN) 232 return (LWRES_R_FAILURE); 233 234 lwres_buffer_getmem(b, addr->address, addr->length); 235 236 return (LWRES_R_SUCCESS); 237} 238 239/*% Used to perform forward lookups. */ 240lwres_result_t 241lwres_getaddrsbyname(lwres_context_t *ctx, const char *name, 242 lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp) 243{ 244 lwres_gabnrequest_t request; 245 lwres_gabnresponse_t *response; 246 int ret; 247 int recvlen; 248 lwres_buffer_t b_in, b_out; 249 lwres_lwpacket_t pkt; 250 lwres_uint32_t serial; 251 char *buffer; 252 char target_name[1024]; 253 unsigned int target_length; 254 255 REQUIRE(ctx != NULL); 256 REQUIRE(name != NULL); 257 REQUIRE(addrtypes != 0); 258 REQUIRE(structp != NULL && *structp == NULL); 259 260 b_in.base = NULL; 261 b_out.base = NULL; 262 response = NULL; 263 buffer = NULL; 264 serial = lwres_context_nextserial(ctx); 265 266 buffer = CTXMALLOC(LWRES_RECVLENGTH); 267 if (buffer == NULL) { 268 ret = LWRES_R_NOMEMORY; 269 goto out; 270 } 271 272 target_length = strlen(name); 273 if (target_length >= sizeof(target_name)) 274 return (LWRES_R_FAILURE); 275 strcpy(target_name, name); /* strcpy is safe */ 276 277 /* 278 * Set up our request and render it to a buffer. 279 */ 280 request.flags = 0; 281 request.addrtypes = addrtypes; 282 request.name = target_name; 283 request.namelen = target_length; 284 pkt.pktflags = 0; 285 pkt.serial = serial; 286 pkt.result = 0; 287 pkt.recvlength = LWRES_RECVLENGTH; 288 289 again: 290 ret = lwres_gabnrequest_render(ctx, &request, &pkt, &b_out); 291 if (ret != LWRES_R_SUCCESS) 292 goto out; 293 294 ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, 295 LWRES_RECVLENGTH, &recvlen); 296 if (ret != LWRES_R_SUCCESS) 297 goto out; 298 299 lwres_buffer_init(&b_in, buffer, recvlen); 300 b_in.used = recvlen; 301 302 /* 303 * Parse the packet header. 304 */ 305 ret = lwres_lwpacket_parseheader(&b_in, &pkt); 306 if (ret != LWRES_R_SUCCESS) 307 goto out; 308 309 /* 310 * Sanity check. 311 */ 312 if (pkt.serial != serial) 313 goto again; 314 if (pkt.opcode != LWRES_OPCODE_GETADDRSBYNAME) 315 goto again; 316 317 /* 318 * Free what we've transmitted 319 */ 320 CTXFREE(b_out.base, b_out.length); 321 b_out.base = NULL; 322 b_out.length = 0; 323 324 if (pkt.result != LWRES_R_SUCCESS) { 325 ret = pkt.result; 326 goto out; 327 } 328 329 /* 330 * Parse the response. 331 */ 332 ret = lwres_gabnresponse_parse(ctx, &b_in, &pkt, &response); 333 if (ret != LWRES_R_SUCCESS) 334 goto out; 335 response->base = buffer; 336 response->baselen = LWRES_RECVLENGTH; 337 buffer = NULL; /* don't free this below */ 338 339 *structp = response; 340 return (LWRES_R_SUCCESS); 341 342 out: 343 if (b_out.base != NULL) 344 CTXFREE(b_out.base, b_out.length); 345 if (buffer != NULL) 346 CTXFREE(buffer, LWRES_RECVLENGTH); 347 if (response != NULL) 348 lwres_gabnresponse_free(ctx, &response); 349 350 return (ret); 351} 352 353 354/*% Used to perform reverse lookups. */ 355lwres_result_t 356lwres_getnamebyaddr(lwres_context_t *ctx, lwres_uint32_t addrtype, 357 lwres_uint16_t addrlen, const unsigned char *addr, 358 lwres_gnbaresponse_t **structp) 359{ 360 lwres_gnbarequest_t request; 361 lwres_gnbaresponse_t *response; 362 int ret; 363 int recvlen; 364 lwres_buffer_t b_in, b_out; 365 lwres_lwpacket_t pkt; 366 lwres_uint32_t serial; 367 char *buffer; 368 369 REQUIRE(ctx != NULL); 370 REQUIRE(addrtype != 0); 371 REQUIRE(addrlen != 0); 372 REQUIRE(addr != NULL); 373 REQUIRE(structp != NULL && *structp == NULL); 374 375 b_in.base = NULL; 376 b_out.base = NULL; 377 response = NULL; 378 buffer = NULL; 379 serial = lwres_context_nextserial(ctx); 380 381 buffer = CTXMALLOC(LWRES_RECVLENGTH); 382 if (buffer == NULL) { 383 ret = LWRES_R_NOMEMORY; 384 goto out; 385 } 386 387 /* 388 * Set up our request and render it to a buffer. 389 */ 390 request.flags = 0; 391 request.addr.family = addrtype; 392 request.addr.length = addrlen; 393 memcpy(request.addr.address, addr, addrlen); 394 pkt.pktflags = 0; 395 pkt.serial = serial; 396 pkt.result = 0; 397 pkt.recvlength = LWRES_RECVLENGTH; 398 399 again: 400 ret = lwres_gnbarequest_render(ctx, &request, &pkt, &b_out); 401 if (ret != LWRES_R_SUCCESS) 402 goto out; 403 404 ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, 405 LWRES_RECVLENGTH, &recvlen); 406 if (ret != LWRES_R_SUCCESS) 407 goto out; 408 409 lwres_buffer_init(&b_in, buffer, recvlen); 410 b_in.used = recvlen; 411 412 /* 413 * Parse the packet header. 414 */ 415 ret = lwres_lwpacket_parseheader(&b_in, &pkt); 416 if (ret != LWRES_R_SUCCESS) 417 goto out; 418 419 /* 420 * Sanity check. 421 */ 422 if (pkt.serial != serial) 423 goto again; 424 if (pkt.opcode != LWRES_OPCODE_GETNAMEBYADDR) 425 goto again; 426 427 /* 428 * Free what we've transmitted 429 */ 430 CTXFREE(b_out.base, b_out.length); 431 b_out.base = NULL; 432 b_out.length = 0; 433 434 if (pkt.result != LWRES_R_SUCCESS) { 435 ret = pkt.result; 436 goto out; 437 } 438 439 /* 440 * Parse the response. 441 */ 442 ret = lwres_gnbaresponse_parse(ctx, &b_in, &pkt, &response); 443 if (ret != LWRES_R_SUCCESS) 444 goto out; 445 response->base = buffer; 446 response->baselen = LWRES_RECVLENGTH; 447 buffer = NULL; /* don't free this below */ 448 449 *structp = response; 450 return (LWRES_R_SUCCESS); 451 452 out: 453 if (b_out.base != NULL) 454 CTXFREE(b_out.base, b_out.length); 455 if (buffer != NULL) 456 CTXFREE(buffer, LWRES_RECVLENGTH); 457 if (response != NULL) 458 lwres_gnbaresponse_free(ctx, &response); 459 460 return (ret); 461} 462 463/*% Get rdata by name. */ 464lwres_result_t 465lwres_getrdatabyname(lwres_context_t *ctx, const char *name, 466 lwres_uint16_t rdclass, lwres_uint16_t rdtype, 467 lwres_uint32_t flags, lwres_grbnresponse_t **structp) 468{ 469 int ret; 470 int recvlen; 471 lwres_buffer_t b_in, b_out; 472 lwres_lwpacket_t pkt; 473 lwres_uint32_t serial; 474 char *buffer; 475 lwres_grbnrequest_t request; 476 lwres_grbnresponse_t *response; 477 char target_name[1024]; 478 unsigned int target_length; 479 480 REQUIRE(ctx != NULL); 481 REQUIRE(name != NULL); 482 REQUIRE(structp != NULL && *structp == NULL); 483 484 b_in.base = NULL; 485 b_out.base = NULL; 486 response = NULL; 487 buffer = NULL; 488 serial = lwres_context_nextserial(ctx); 489 490 buffer = CTXMALLOC(LWRES_RECVLENGTH); 491 if (buffer == NULL) { 492 ret = LWRES_R_NOMEMORY; 493 goto out; 494 } 495 496 target_length = strlen(name); 497 if (target_length >= sizeof(target_name)) 498 return (LWRES_R_FAILURE); 499 strcpy(target_name, name); /* strcpy is safe */ 500 501 /* 502 * Set up our request and render it to a buffer. 503 */ 504 request.rdclass = rdclass; 505 request.rdtype = rdtype; 506 request.flags = flags; 507 request.name = target_name; 508 request.namelen = target_length; 509 pkt.pktflags = 0; 510 pkt.serial = serial; 511 pkt.result = 0; 512 pkt.recvlength = LWRES_RECVLENGTH; 513 514 again: 515 ret = lwres_grbnrequest_render(ctx, &request, &pkt, &b_out); 516 if (ret != LWRES_R_SUCCESS) 517 goto out; 518 519 ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, 520 LWRES_RECVLENGTH, &recvlen); 521 if (ret != LWRES_R_SUCCESS) 522 goto out; 523 524 lwres_buffer_init(&b_in, buffer, recvlen); 525 b_in.used = recvlen; 526 527 /* 528 * Parse the packet header. 529 */ 530 ret = lwres_lwpacket_parseheader(&b_in, &pkt); 531 if (ret != LWRES_R_SUCCESS) 532 goto out; 533 534 /* 535 * Sanity check. 536 */ 537 if (pkt.serial != serial) 538 goto again; 539 if (pkt.opcode != LWRES_OPCODE_GETRDATABYNAME) 540 goto again; 541 542 /* 543 * Free what we've transmitted 544 */ 545 CTXFREE(b_out.base, b_out.length); 546 b_out.base = NULL; 547 b_out.length = 0; 548 549 if (pkt.result != LWRES_R_SUCCESS) { 550 ret = pkt.result; 551 goto out; 552 } 553 554 /* 555 * Parse the response. 556 */ 557 ret = lwres_grbnresponse_parse(ctx, &b_in, &pkt, &response); 558 if (ret != LWRES_R_SUCCESS) 559 goto out; 560 response->base = buffer; 561 response->baselen = LWRES_RECVLENGTH; 562 buffer = NULL; /* don't free this below */ 563 564 *structp = response; 565 return (LWRES_R_SUCCESS); 566 567 out: 568 if (b_out.base != NULL) 569 CTXFREE(b_out.base, b_out.length); 570 if (buffer != NULL) 571 CTXFREE(buffer, LWRES_RECVLENGTH); 572 if (response != NULL) 573 lwres_grbnresponse_free(ctx, &response); 574 575 return (ret); 576} 577