contrib/bind-9.5.2/lib/lwres/context.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007-2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 2000, 2001, 2003  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: context.c,v 1.50.128.5 2009/09/01 23:46:36 tbox Exp $ */
  19
  20 /*! \file context.c
  21    lwres_context_create() creates a #lwres_context_t structure for use in
  22    lightweight resolver operations. It holds a socket and other data
  23    needed for communicating with a resolver daemon. The new
  24    lwres_context_t is returned through contextp, a pointer to a
  25    lwres_context_t pointer. This lwres_context_t pointer must initially
  26    be NULL, and is modified to point to the newly created
  27    lwres_context_t.
  28
  29    When the lightweight resolver needs to perform dynamic memory
  30    allocation, it will call malloc_function to allocate memory and
  31    free_function to free it. If malloc_function and free_function are
  32    NULL, memory is allocated using malloc and free. It is not
  33    permitted to have a NULL malloc_function and a non-NULL free_function
  34    or vice versa. arg is passed as the first parameter to the memory
  35    allocation functions. If malloc_function and free_function are NULL,
  36    arg is unused and should be passed as NULL.
  37
  38    Once memory for the structure has been allocated, it is initialized
  39    using lwres_conf_init() and returned via *contextp.
  40
  41    lwres_context_destroy() destroys a #lwres_context_t, closing its
  42    socket. contextp is a pointer to a pointer to the context that is to
  43    be destroyed. The pointer will be set to NULL when the context has
  44    been destroyed.
  45
  46    The context holds a serial number that is used to identify resolver
  47    request packets and associate responses with the corresponding
  48    requests. This serial number is controlled using
  49    lwres_context_initserial() and lwres_context_nextserial().
  50    lwres_context_initserial() sets the serial number for context *ctx to
  51    serial. lwres_context_nextserial() increments the serial number and
  52    returns the previous value.
  53
  54    Memory for a lightweight resolver context is allocated and freed using
  55    lwres_context_allocmem() and lwres_context_freemem(). These use
  56    whatever allocations were defined when the context was created with
  57    lwres_context_create(). lwres_context_allocmem() allocates len bytes
  58    of memory and if successful returns a pointer to the allocated
  59    storage. lwres_context_freemem() frees len bytes of space starting at
  60    location mem.
  61
  62    lwres_context_sendrecv() performs I/O for the context ctx. Data are
  63    read and written from the context's socket. It writes data from
  64    sendbase -- typically a lightweight resolver query packet -- and waits
  65    for a reply which is copied to the receive buffer at recvbase. The
  66    number of bytes that were written to this receive buffer is returned
  67    in *recvd_len.
  68
  69 \section context_return Return Values
  70
  71    lwres_context_create() returns #LWRES_R_NOMEMORY if memory for the
  72    struct lwres_context could not be allocated, #LWRES_R_SUCCESS
  73    otherwise.
  74
  75    Successful calls to the memory allocator lwres_context_allocmem()
  76    return a pointer to the start of the allocated space. It returns NULL
  77    if memory could not be allocated.
  78
  79    #LWRES_R_SUCCESS is returned when lwres_context_sendrecv() completes
  80    successfully. #LWRES_R_IOERROR is returned if an I/O error occurs and
  81    #LWRES_R_TIMEOUT is returned if lwres_context_sendrecv() times out
  82    waiting for a response.
  83
  84 \section context_see See Also
  85
  86    lwres_conf_init(), malloc, free.
  87  */
  88 #include <config.h>
  89
  90 #include <fcntl.h>
  91 #include <limits.h>
  92 #include <stdlib.h>
  93 #include <string.h>
  94 #include <time.h>
  95 #include <unistd.h>
  96
  97 #include <lwres/lwres.h>
  98 #include <lwres/net.h>
  99 #include <lwres/platform.h>
 100
 101 #ifdef LWRES_PLATFORM_NEEDSYSSELECTH
 102 #include <sys/select.h>
 103 #endif
 104
 105 #include "context_p.h"
 106 #include "assert_p.h"
 107
 108 /*!
 109  * Some systems define the socket length argument as an int, some as size_t,
 110  * some as socklen_t.  The last is what the current POSIX standard mandates.
 111  * This definition is here so it can be portable but easily changed if needed.
 112  */
 113 #ifndef LWRES_SOCKADDR_LEN_T
 114 #define LWRES_SOCKADDR_LEN_T unsigned int
 115 #endif
 116
 117 /*!
 118  * Make a socket nonblocking.
 119  */
 120 #ifndef MAKE_NONBLOCKING
 121 #define MAKE_NONBLOCKING(sd, retval) \
 122 do { \
 123         retval = fcntl(sd, F_GETFL, 0); \
 124         if (retval != -1) { \
 125                 retval |= O_NONBLOCK; \
 126                 retval = fcntl(sd, F_SETFL, retval); \
 127         } \
 128 } while (0)
 129 #endif
 130
 131 LIBLWRES_EXTERNAL_DATA lwres_uint16_t lwres_udp_port = LWRES_UDP_PORT;
 132 LIBLWRES_EXTERNAL_DATA const char *lwres_resolv_conf = LWRES_RESOLV_CONF;
 133
 134 static void *
 135 lwres_malloc(void *, size_t);
 136
 137 static void
 138 lwres_free(void *, void *, size_t);
 139
 140 /*!
 141  * lwres_result_t
 142  */
 143 static lwres_result_t
 144 context_connect(lwres_context_t *);
 145
 146 /*%
 147  * Creates a #lwres_context_t structure for use in
 148  *  lightweight resolver operations.
 149  */
 150 lwres_result_t
 151 lwres_context_create(lwres_context_t **contextp, void *arg,
 152                      lwres_malloc_t malloc_function,
 153                      lwres_free_t free_function,
 154                      unsigned int flags)
 155 {
 156         lwres_context_t *ctx;
 157
 158         REQUIRE(contextp != NULL && *contextp == NULL);
 159
 160         /*
 161          * If we were not given anything special to use, use our own
 162          * functions.  These are just wrappers around malloc() and free().
 163          */
 164         if (malloc_function == NULL || free_function == NULL) {
 165                 REQUIRE(malloc_function == NULL);
 166                 REQUIRE(free_function == NULL);
 167                 malloc_function = lwres_malloc;
 168                 free_function = lwres_free;
 169         }
 170
 171         ctx = malloc_function(arg, sizeof(lwres_context_t));
 172         if (ctx == NULL)
 173                 return (LWRES_R_NOMEMORY);
 174
 175         /*
 176          * Set up the context.
 177          */
 178         ctx->malloc = malloc_function;
 179         ctx->free = free_function;
 180         ctx->arg = arg;
 181         ctx->sock = -1;
 182
 183         ctx->timeout = LWRES_DEFAULT_TIMEOUT;
 184         ctx->serial = time(NULL); /* XXXMLG or BEW */
 185
 186         ctx->use_ipv4 = 1;
 187         ctx->use_ipv6 = 1;
 188         if ((flags & (LWRES_CONTEXT_USEIPV4 | LWRES_CONTEXT_USEIPV6)) ==
 189             LWRES_CONTEXT_USEIPV6) {
 190                 ctx->use_ipv4 = 0;
 191         }
 192         if ((flags & (LWRES_CONTEXT_USEIPV4 | LWRES_CONTEXT_USEIPV6)) ==
 193             LWRES_CONTEXT_USEIPV4) {
 194                 ctx->use_ipv6 = 0;
 195         }
 196
 197         /*
 198          * Init resolv.conf bits.
 199          */
 200         lwres_conf_init(ctx);
 201
 202         *contextp = ctx;
 203         return (LWRES_R_SUCCESS);
 204 }
 205
 206 /*%
 207 Destroys a #lwres_context_t, closing its socket.
 208 contextp is a pointer to a pointer to the context that is
 209 to be destroyed. The pointer will be set to NULL
 210 when the context has been destroyed.
 211  */
 212 void
 213 lwres_context_destroy(lwres_context_t **contextp) {
 214         lwres_context_t *ctx;
 215
 216         REQUIRE(contextp != NULL && *contextp != NULL);
 217
 218         ctx = *contextp;
 219         *contextp = NULL;
 220
 221         if (ctx->sock != -1) {
 222 #ifdef WIN32
 223                 DestroySockets();
 224 #endif
 225                 (void)close(ctx->sock);
 226                 ctx->sock = -1;
 227         }
 228
 229         CTXFREE(ctx, sizeof(lwres_context_t));
 230 }
 231 /*% Increments the serial number and returns the previous value. */
 232 lwres_uint32_t
 233 lwres_context_nextserial(lwres_context_t *ctx) {
 234         REQUIRE(ctx != NULL);
 235
 236         return (ctx->serial++);
 237 }
 238
 239 /*% Sets the serial number for context *ctx to serial. */
 240 void
 241 lwres_context_initserial(lwres_context_t *ctx, lwres_uint32_t serial) {
 242         REQUIRE(ctx != NULL);
 243
 244         ctx->serial = serial;
 245 }
 246
 247 /*% Frees len bytes of space starting at location mem. */
 248 void
 249 lwres_context_freemem(lwres_context_t *ctx, void *mem, size_t len) {
 250         REQUIRE(mem != NULL);
 251         REQUIRE(len != 0U);
 252
 253         CTXFREE(mem, len);
 254 }
 255
 256 /*% Allocates len bytes of memory and if successful returns a pointer to the allocated storage. */
 257 void *
 258 lwres_context_allocmem(lwres_context_t *ctx, size_t len) {
 259         REQUIRE(len != 0U);
 260
 261         return (CTXMALLOC(len));
 262 }
 263
 264 static void *
 265 lwres_malloc(void *arg, size_t len) {
 266         void *mem;
 267
 268         UNUSED(arg);
 269
 270         mem = malloc(len);
 271         if (mem == NULL)
 272                 return (NULL);
 273
 274         memset(mem, 0xe5, len);
 275
 276         return (mem);
 277 }
 278
 279 static void
 280 lwres_free(void *arg, void *mem, size_t len) {
 281         UNUSED(arg);
 282
 283         memset(mem, 0xa9, len);
 284         free(mem);
 285 }
 286
 287 static lwres_result_t
 288 context_connect(lwres_context_t *ctx) {
 289         int s;
 290         int ret;
 291         struct sockaddr_in sin;
 292         struct sockaddr_in6 sin6;
 293         struct sockaddr *sa;
 294         LWRES_SOCKADDR_LEN_T salen;
 295         int domain;
 296
 297         if (ctx->confdata.lwnext != 0) {
 298                 memcpy(&ctx->address, &ctx->confdata.lwservers[0],
 299                        sizeof(lwres_addr_t));
 300                 LWRES_LINK_INIT(&ctx->address, link);
 301         } else {
 302                 /* The default is the IPv4 loopback address 127.0.0.1. */
 303                 memset(&ctx->address, 0, sizeof(ctx->address));
 304                 ctx->address.family = LWRES_ADDRTYPE_V4;
 305                 ctx->address.length = 4;
 306                 ctx->address.address[0] = 127;
 307                 ctx->address.address[1] = 0;
 308                 ctx->address.address[2] = 0;
 309                 ctx->address.address[3] = 1;
 310         }
 311
 312         if (ctx->address.family == LWRES_ADDRTYPE_V4) {
 313                 memcpy(&sin.sin_addr, ctx->address.address,
 314                        sizeof(sin.sin_addr));
 315                 sin.sin_port = htons(lwres_udp_port);
 316                 sin.sin_family = AF_INET;
 317                 sa = (struct sockaddr *)&sin;
 318                 salen = sizeof(sin);
 319                 domain = PF_INET;
 320         } else if (ctx->address.family == LWRES_ADDRTYPE_V6) {
 321                 memcpy(&sin6.sin6_addr, ctx->address.address,
 322                        sizeof(sin6.sin6_addr));
 323                 sin6.sin6_port = htons(lwres_udp_port);
 324                 sin6.sin6_family = AF_INET6;
 325                 sa = (struct sockaddr *)&sin6;
 326                 salen = sizeof(sin6);
 327                 domain = PF_INET6;
 328         } else
 329                 return (LWRES_R_IOERROR);
 330
 331 #ifdef WIN32
 332         InitSockets();
 333 #endif
 334         s = socket(domain, SOCK_DGRAM, IPPROTO_UDP);
 335         if (s < 0) {
 336 #ifdef WIN32
 337                 DestroySockets();
 338 #endif
 339                 return (LWRES_R_IOERROR);
 340         }
 341
 342         ret = connect(s, sa, salen);
 343         if (ret != 0) {
 344 #ifdef WIN32
 345                 DestroySockets();
 346 #endif
 347                 (void)close(s);
 348                 return (LWRES_R_IOERROR);
 349         }
 350
 351         MAKE_NONBLOCKING(s, ret);
 352         if (ret < 0) {
 353 #ifdef WIN32
 354                 DestroySockets();
 355 #endif
 356                 (void)close(s);
 357                 return (LWRES_R_IOERROR);
 358         }
 359
 360         ctx->sock = s;
 361
 362         return (LWRES_R_SUCCESS);
 363 }
 364
 365 int
 366 lwres_context_getsocket(lwres_context_t *ctx) {
 367         return (ctx->sock);
 368 }
 369
 370 lwres_result_t
 371 lwres_context_send(lwres_context_t *ctx,
 372                    void *sendbase, int sendlen) {
 373         int ret;
 374         lwres_result_t lwresult;
 375
 376         if (ctx->sock == -1) {
 377                 lwresult = context_connect(ctx);
 378                 if (lwresult != LWRES_R_SUCCESS)
 379                         return (lwresult);
 380         }
 381
 382         ret = sendto(ctx->sock, sendbase, sendlen, 0, NULL, 0);
 383         if (ret < 0)
 384                 return (LWRES_R_IOERROR);
 385         if (ret != sendlen)
 386                 return (LWRES_R_IOERROR);
 387
 388         return (LWRES_R_SUCCESS);
 389 }
 390
 391 lwres_result_t
 392 lwres_context_recv(lwres_context_t *ctx,
 393                    void *recvbase, int recvlen,
 394                    int *recvd_len)
 395 {
 396         LWRES_SOCKADDR_LEN_T fromlen;
 397         struct sockaddr_in sin;
 398         struct sockaddr_in6 sin6;
 399         struct sockaddr *sa;
 400         int ret;
 401
 402         if (ctx->address.family == LWRES_ADDRTYPE_V4) {
 403                 sa = (struct sockaddr *)&sin;
 404                 fromlen = sizeof(sin);
 405         } else {
 406                 sa = (struct sockaddr *)&sin6;
 407                 fromlen = sizeof(sin6);
 408         }
 409
 410         /*
 411          * The address of fromlen is cast to void * to shut up compiler
 412          * warnings, namely on systems that have the sixth parameter
 413          * prototyped as a signed int when LWRES_SOCKADDR_LEN_T is
 414          * defined as unsigned.
 415          */
 416         ret = recvfrom(ctx->sock, recvbase, recvlen, 0, sa, (void *)&fromlen);
 417
 418         if (ret < 0)
 419                 return (LWRES_R_IOERROR);
 420
 421         if (ret == recvlen)
 422                 return (LWRES_R_TOOLARGE);
 423
 424         /*
 425          * If we got something other than what we expect, have the caller
 426          * wait for another packet.  This can happen if an old result
 427          * comes in, or if someone is sending us random stuff.
 428          */
 429         if (ctx->address.family == LWRES_ADDRTYPE_V4) {
 430                 if (fromlen != sizeof(sin)
 431                     || memcmp(&sin.sin_addr, ctx->address.address,
 432                               sizeof(sin.sin_addr)) != 0
 433                     || sin.sin_port != htons(lwres_udp_port))
 434                         return (LWRES_R_RETRY);
 435         } else {
 436                 if (fromlen != sizeof(sin6)
 437                     || memcmp(&sin6.sin6_addr, ctx->address.address,
 438                               sizeof(sin6.sin6_addr)) != 0
 439                     || sin6.sin6_port != htons(lwres_udp_port))
 440                         return (LWRES_R_RETRY);
 441         }
 442
 443         if (recvd_len != NULL)
 444                 *recvd_len = ret;
 445
 446         return (LWRES_R_SUCCESS);
 447 }
 448
 449 /*% performs I/O for the context ctx. */
 450 lwres_result_t
 451 lwres_context_sendrecv(lwres_context_t *ctx,
 452                        void *sendbase, int sendlen,
 453                        void *recvbase, int recvlen,
 454                        int *recvd_len)
 455 {
 456         lwres_result_t result;
 457         int ret2;
 458         fd_set readfds;
 459         struct timeval timeout;
 460
 461         /*
 462          * Type of tv_sec is 32 bits long.
 463          */
 464         if (ctx->timeout <= 0x7FFFFFFFU)
 465                 timeout.tv_sec = (int)ctx->timeout;
 466         else
 467                 timeout.tv_sec = 0x7FFFFFFF;
 468
 469         timeout.tv_usec = 0;
 470
 471         result = lwres_context_send(ctx, sendbase, sendlen);
 472         if (result != LWRES_R_SUCCESS)
 473                 return (result);
 474  again:
 475         FD_ZERO(&readfds);
 476         FD_SET(ctx->sock, &readfds);
 477         ret2 = select(ctx->sock + 1, &readfds, NULL, NULL, &timeout);
 478
 479         /*
 480          * What happened with select?
 481          */
 482         if (ret2 < 0)
 483                 return (LWRES_R_IOERROR);
 484         if (ret2 == 0)
 485                 return (LWRES_R_TIMEOUT);
 486
 487         result = lwres_context_recv(ctx, recvbase, recvlen, recvd_len);
 488         if (result == LWRES_R_RETRY)
 489                 goto again;
 490
 491         return (result);
 492 }