contrib/bind-9.2.4rc7/lib/lwres/getaddrinfo.c

   1 /*
   2  * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001  Internet Software Consortium.
   4  *
   5  * This code is derived from software contributed to ISC by
   6  * Berkeley Software Design, Inc.
   7  *
   8  * Permission to use, copy, modify, and distribute this software for any
   9  * purpose with or without fee is hereby granted, provided that the above
  10  * copyright notice and this permission notice appear in all copies.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC AND BERKELEY SOFTWARE DESIGN, INC.
  13  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
  14  * WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE
  15  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  16  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  17  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
  18  * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  19  */
  20
  21 /* $Id: getaddrinfo.c,v 1.41.2.1 2004/03/09 06:12:33 marka Exp $ */
  22
  23 #include <config.h>
  24
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <stdlib.h>
  28
  29 #include <lwres/lwres.h>
  30 #include <lwres/net.h>
  31 #include <lwres/netdb.h>
  32
  33 #define SA(addr)        ((struct sockaddr *)(addr))
  34 #define SIN(addr)       ((struct sockaddr_in *)(addr))
  35 #define SIN6(addr)      ((struct sockaddr_in6 *)(addr))
  36 #define SUN(addr)       ((struct sockaddr_un *)(addr))
  37
  38 static struct addrinfo
  39         *ai_reverse(struct addrinfo *oai),
  40         *ai_clone(struct addrinfo *oai, int family),
  41         *ai_alloc(int family, int addrlen);
  42 #ifdef AF_LOCAL
  43 static int get_local(const char *name, int socktype, struct addrinfo **res);
  44 #endif
  45
  46 static int add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
  47     int socktype, int port);
  48 static int add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
  49     int socktype, int port);
  50 static void set_order(int, int (**)(const char *, int, struct addrinfo **,
  51          int, int));
  52
  53 #define FOUND_IPV4      0x1
  54 #define FOUND_IPV6      0x2
  55 #define FOUND_MAX       2
  56
  57 #define ISC_AI_MASK (AI_PASSIVE|AI_CANONNAME|AI_NUMERICHOST)
  58
  59 int
  60 lwres_getaddrinfo(const char *hostname, const char *servname,
  61         const struct addrinfo *hints, struct addrinfo **res)
  62 {
  63         struct servent *sp;
  64         const char *proto;
  65         int family, socktype, flags, protocol;
  66         struct addrinfo *ai, *ai_list;
  67         int port, err, i;
  68         int (*net_order[FOUND_MAX+1])(const char *, int, struct addrinfo **,
  69                  int, int);
  70
  71         if (hostname == NULL && servname == NULL)
  72                 return (EAI_NONAME);
  73
  74         proto = NULL;
  75         if (hints != NULL) {
  76                 if ((hints->ai_flags & ~(ISC_AI_MASK)) != 0)
  77                         return (EAI_BADFLAGS);
  78                 if (hints->ai_addrlen || hints->ai_canonname ||
  79                     hints->ai_addr || hints->ai_next) {
  80                         errno = EINVAL;
  81                         return (EAI_SYSTEM);
  82                 }
  83                 family = hints->ai_family;
  84                 socktype = hints->ai_socktype;
  85                 protocol = hints->ai_protocol;
  86                 flags = hints->ai_flags;
  87                 switch (family) {
  88                 case AF_UNSPEC:
  89                         switch (hints->ai_socktype) {
  90                         case SOCK_STREAM:
  91                                 proto = "tcp";
  92                                 break;
  93                         case SOCK_DGRAM:
  94                                 proto = "udp";
  95                                 break;
  96                         }
  97                         break;
  98                 case AF_INET:
  99                 case AF_INET6:
 100                         switch (hints->ai_socktype) {
 101                         case 0:
 102                                 break;
 103                         case SOCK_STREAM:
 104                                 proto = "tcp";
 105                                 break;
 106                         case SOCK_DGRAM:
 107                                 proto = "udp";
 108                                 break;
 109                         case SOCK_RAW:
 110                                 break;
 111                         default:
 112                                 return (EAI_SOCKTYPE);
 113                         }
 114                         break;
 115 #ifdef  AF_LOCAL
 116                 case AF_LOCAL:
 117                         switch (hints->ai_socktype) {
 118                         case 0:
 119                                 break;
 120                         case SOCK_STREAM:
 121                                 break;
 122                         case SOCK_DGRAM:
 123                                 break;
 124                         default:
 125                                 return (EAI_SOCKTYPE);
 126                         }
 127                         break;
 128 #endif
 129                 default:
 130                         return (EAI_FAMILY);
 131                 }
 132         } else {
 133                 protocol = 0;
 134                 family = 0;
 135                 socktype = 0;
 136                 flags = 0;
 137         }
 138
 139 #ifdef  AF_LOCAL
 140         /*
 141          * First, deal with AF_LOCAL.  If the family was not set,
 142          * then assume AF_LOCAL if the first character of the
 143          * hostname/servname is '/'.
 144          */
 145
 146         if (hostname != NULL &&
 147             (family == AF_LOCAL || (family == 0 && *hostname == '/')))
 148                 return (get_local(hostname, socktype, res));
 149
 150         if (servname != NULL &&
 151             (family == AF_LOCAL || (family == 0 && *servname == '/')))
 152                 return (get_local(servname, socktype, res));
 153 #endif
 154
 155         /*
 156          * Ok, only AF_INET and AF_INET6 left.
 157          */
 158         ai_list = NULL;
 159
 160         /*
 161          * First, look up the service name (port) if it was
 162          * requested.  If the socket type wasn't specified, then
 163          * try and figure it out.
 164          */
 165         if (servname != NULL) {
 166                 char *e;
 167
 168                 port = strtol(servname, &e, 10);
 169                 if (*e == '\0') {
 170                         if (socktype == 0)
 171                                 return (EAI_SOCKTYPE);
 172                         if (port < 0 || port > 65535)
 173                                 return (EAI_SERVICE);
 174                         port = htons((unsigned short) port);
 175                 } else {
 176                         sp = getservbyname(servname, proto);
 177                         if (sp == NULL)
 178                                 return (EAI_SERVICE);
 179                         port = sp->s_port;
 180                         if (socktype == 0) {
 181                                 if (strcmp(sp->s_proto, "tcp") == 0)
 182                                         socktype = SOCK_STREAM;
 183                                 else if (strcmp(sp->s_proto, "udp") == 0)
 184                                         socktype = SOCK_DGRAM;
 185                         }
 186                 }
 187         } else
 188                 port = 0;
 189
 190         /*
 191          * Next, deal with just a service name, and no hostname.
 192          * (we verified that one of them was non-null up above).
 193          */
 194         if (hostname == NULL && (flags & AI_PASSIVE) != 0) {
 195                 if (family == AF_INET || family == 0) {
 196                         ai = ai_alloc(AF_INET, sizeof(struct sockaddr_in));
 197                         if (ai == NULL)
 198                                 return (EAI_MEMORY);
 199                         ai->ai_socktype = socktype;
 200                         ai->ai_protocol = protocol;
 201                         SIN(ai->ai_addr)->sin_port = port;
 202                         ai->ai_next = ai_list;
 203                         ai_list = ai;
 204                 }
 205
 206                 if (family == AF_INET6 || family == 0) {
 207                         ai = ai_alloc(AF_INET6, sizeof(struct sockaddr_in6));
 208                         if (ai == NULL) {
 209                                 lwres_freeaddrinfo(ai_list);
 210                                 return (EAI_MEMORY);
 211                         }
 212                         ai->ai_socktype = socktype;
 213                         ai->ai_protocol = protocol;
 214                         SIN6(ai->ai_addr)->sin6_port = port;
 215                         ai->ai_next = ai_list;
 216                         ai_list = ai;
 217                 }
 218
 219                 *res = ai_list;
 220                 return (0);
 221         }
 222
 223         /*
 224          * If the family isn't specified or AI_NUMERICHOST specified,
 225          * check first to see if it is a numeric address.
 226          * Though the gethostbyname2() routine
 227          * will recognize numeric addresses, it will only recognize
 228          * the format that it is being called for.  Thus, a numeric
 229          * AF_INET address will be treated by the AF_INET6 call as
 230          * a domain name, and vice versa.  Checking for both numerics
 231          * here avoids that.
 232          */
 233         if (hostname != NULL &&
 234             (family == 0 || (flags & AI_NUMERICHOST) != 0)) {
 235                 char abuf[sizeof(struct in6_addr)];
 236                 char nbuf[NI_MAXHOST];
 237                 int addrsize, addroff;
 238 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 239                 char *p, *ep;
 240                 char ntmp[NI_MAXHOST];
 241                 lwres_uint32_t scopeid;
 242 #endif
 243
 244 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 245                 /*
 246                  * Scope identifier portion.
 247                  */
 248                 ntmp[0] = '\0';
 249                 if (strchr(hostname, '%') != NULL) {
 250                         strncpy(ntmp, hostname, sizeof(ntmp) - 1);
 251                         ntmp[sizeof(ntmp) - 1] = '\0';
 252                         p = strchr(ntmp, '%');
 253                         ep = NULL;
 254
 255                         /*
 256                          * Vendors may want to support non-numeric
 257                          * scopeid around here.
 258                          */
 259
 260                         if (p != NULL)
 261                                 scopeid = (lwres_uint32_t)strtoul(p + 1,
 262                                                                   &ep, 10);
 263                         if (p != NULL && ep != NULL && ep[0] == '\0')
 264                                 *p = '\0';
 265                         else {
 266                                 ntmp[0] = '\0';
 267                                 scopeid = 0;
 268                         }
 269                 } else
 270                         scopeid = 0;
 271 #endif
 272
 273                if (lwres_net_pton(AF_INET, hostname, (struct in_addr *)abuf)
 274                    == 1)
 275                {
 276                         if (family == AF_INET6) {
 277                                 /*
 278                                  * Convert to a V4 mapped address.
 279                                  */
 280                                 struct in6_addr *a6 = (struct in6_addr *)abuf;
 281                                 memcpy(&a6->s6_addr[12], &a6->s6_addr[0], 4);
 282                                 memset(&a6->s6_addr[10], 0xff, 2);
 283                                 memset(&a6->s6_addr[0], 0, 10);
 284                                 goto inet6_addr;
 285                         }
 286                         addrsize = sizeof(struct in_addr);
 287                         addroff = (char *)(&SIN(0)->sin_addr) - (char *)0;
 288                         family = AF_INET;
 289                         goto common;
 290 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 291                 } else if (ntmp[0] != '\0' &&
 292                            lwres_net_pton(AF_INET6, ntmp, abuf) == 1)
 293                 {
 294                         if (family && family != AF_INET6)
 295                                 return (EAI_NONAME);
 296                         addrsize = sizeof(struct in6_addr);
 297                         addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
 298                         family = AF_INET6;
 299                         goto common;
 300 #endif
 301                 } else if (lwres_net_pton(AF_INET6, hostname, abuf) == 1) {
 302                         if (family != 0 && family != AF_INET6)
 303                                 return (EAI_NONAME);
 304                 inet6_addr:
 305                         addrsize = sizeof(struct in6_addr);
 306                         addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
 307                         family = AF_INET6;
 308
 309                 common:
 310                         ai = ai_clone(ai_list, family);
 311                         if (ai == NULL)
 312                                 return (EAI_MEMORY);
 313                         ai_list = ai;
 314                         ai->ai_socktype = socktype;
 315                         SIN(ai->ai_addr)->sin_port = port;
 316                         memcpy((char *)ai->ai_addr + addroff, abuf, addrsize);
 317                         if (flags & AI_CANONNAME) {
 318 #if defined(LWRES_HAVE_SIN6_SCOPE_ID)
 319                                 if (ai->ai_family == AF_INET6)
 320                                         SIN6(ai->ai_addr)->sin6_scope_id =
 321                                                                         scopeid;
 322 #endif
 323                                 if (lwres_getnameinfo(ai->ai_addr,
 324                                     ai->ai_addrlen, nbuf, sizeof(nbuf),
 325                                                       NULL, 0,
 326                                                       NI_NUMERICHOST) == 0) {
 327                                         ai->ai_canonname = strdup(nbuf);
 328                                         if (ai->ai_canonname == NULL)
 329                                                 return (EAI_MEMORY);
 330                                 } else {
 331                                         /* XXX raise error? */
 332                                         ai->ai_canonname = NULL;
 333                                 }
 334                         }
 335                         goto done;
 336                 } else if ((flags & AI_NUMERICHOST) != 0) {
 337                         return (EAI_NONAME);
 338                 }
 339         }
 340
 341         set_order(family, net_order);
 342         for (i = 0; i < FOUND_MAX; i++) {
 343                 if (net_order[i] == NULL)
 344                         break;
 345                 err = (net_order[i])(hostname, flags, &ai_list,
 346                                      socktype, port);
 347                 if (err != 0)
 348                         return (err);
 349         }
 350
 351         if (ai_list == NULL)
 352                 return (EAI_NODATA);
 353
 354 done:
 355         ai_list = ai_reverse(ai_list);
 356
 357         *res = ai_list;
 358         return (0);
 359 }
 360
 361 static char *
 362 lwres_strsep(char **stringp, const char *delim) {
 363         char *string = *stringp;
 364         char *s;
 365         const char *d;
 366         char sc, dc;
 367
 368         if (string == NULL)
 369                 return (NULL);
 370
 371         for (s = string; *s != '\0'; s++) {
 372                 sc = *s;
 373                 for (d = delim; (dc = *d) != '\0'; d++)
 374                         if (sc == dc) {
 375                                 *s++ = '\0';
 376                                 *stringp = s;
 377                                 return (string);
 378                         }
 379         }
 380         *stringp = NULL;
 381         return (string);
 382 }
 383
 384 static void
 385 set_order(int family, int (**net_order)(const char *, int, struct addrinfo **,
 386                                         int, int))
 387 {
 388         char *order, *tok;
 389         int found;
 390
 391         if (family) {
 392                 switch (family) {
 393                 case AF_INET:
 394                         *net_order++ = add_ipv4;
 395                         break;
 396                 case AF_INET6:
 397                         *net_order++ = add_ipv6;
 398                         break;
 399                 }
 400         } else {
 401                 order = getenv("NET_ORDER");
 402                 found = 0;
 403                 while (order != NULL) {
 404                         /*
 405                          * We ignore any unknown names.
 406                          */
 407                         tok = lwres_strsep(&order, ":");
 408                         if (strcasecmp(tok, "inet6") == 0) {
 409                                 if ((found & FOUND_IPV6) == 0)
 410                                         *net_order++ = add_ipv6;
 411                                 found |= FOUND_IPV6;
 412                         } else if (strcasecmp(tok, "inet") == 0 ||
 413                             strcasecmp(tok, "inet4") == 0) {
 414                                 if ((found & FOUND_IPV4) == 0)
 415                                         *net_order++ = add_ipv4;
 416                                 found |= FOUND_IPV4;
 417                         }
 418                 }
 419
 420                 /*
 421                  * Add in anything that we didn't find.
 422                  */
 423                 if ((found & FOUND_IPV4) == 0)
 424                         *net_order++ = add_ipv4;
 425                 if ((found & FOUND_IPV6) == 0)
 426                         *net_order++ = add_ipv6;
 427         }
 428         *net_order = NULL;
 429         return;
 430 }
 431
 432 static char v4_loop[4] = { 127, 0, 0, 1 };
 433
 434 /*
 435  * The test against 0 is there to keep the Solaris compiler
 436  * from complaining about "end-of-loop code not reached".
 437  */
 438 #define ERR(code) \
 439         do { result = (code);                   \
 440                 if (result != 0) goto cleanup;  \
 441         } while (0)
 442
 443 static int
 444 add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
 445         int socktype, int port)
 446 {
 447         struct addrinfo *ai;
 448         lwres_context_t *lwrctx = NULL;
 449         lwres_gabnresponse_t *by = NULL;
 450         lwres_addr_t *addr;
 451         lwres_result_t lwres;
 452         int result = 0;
 453
 454         lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
 455         if (lwres != LWRES_R_SUCCESS)
 456                 ERR(EAI_FAIL);
 457         (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
 458         if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
 459                 ai = ai_clone(*aip, AF_INET);
 460                 if (ai == NULL) {
 461                         lwres_freeaddrinfo(*aip);
 462                         ERR(EAI_MEMORY);
 463                 }
 464
 465                 *aip = ai;
 466                 ai->ai_socktype = socktype;
 467                 SIN(ai->ai_addr)->sin_port = port;
 468                 memcpy(&SIN(ai->ai_addr)->sin_addr, v4_loop, 4);
 469         } else {
 470                 lwres = lwres_getaddrsbyname(lwrctx, hostname,
 471                                              LWRES_ADDRTYPE_V4, &by);
 472                 if (lwres != LWRES_R_SUCCESS) {
 473                         if (lwres == LWRES_R_NOTFOUND)
 474                                 goto cleanup;
 475                         else
 476                                 ERR(EAI_FAIL);
 477                 }
 478                 addr = LWRES_LIST_HEAD(by->addrs);
 479                 while (addr != NULL) {
 480                         ai = ai_clone(*aip, AF_INET);
 481                         if (ai == NULL) {
 482                                 lwres_freeaddrinfo(*aip);
 483                                 ERR(EAI_MEMORY);
 484                         }
 485                         *aip = ai;
 486                         ai->ai_socktype = socktype;
 487                         SIN(ai->ai_addr)->sin_port = port;
 488                         memcpy(&SIN(ai->ai_addr)->sin_addr,
 489                                addr->address, 4);
 490                         if (flags & AI_CANONNAME) {
 491                                 ai->ai_canonname = strdup(by->realname);
 492                                 if (ai->ai_canonname == NULL)
 493                                         ERR(EAI_MEMORY);
 494                         }
 495                         addr = LWRES_LIST_NEXT(addr, link);
 496                 }
 497         }
 498  cleanup:
 499         if (by != NULL)
 500                 lwres_gabnresponse_free(lwrctx, &by);
 501         if (lwrctx != NULL) {
 502                 lwres_conf_clear(lwrctx);
 503                 lwres_context_destroy(&lwrctx);
 504         }
 505         return (result);
 506 }
 507
 508 static char v6_loop[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 };
 509
 510 static int
 511 add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
 512          int socktype, int port)
 513 {
 514         struct addrinfo *ai;
 515         lwres_context_t *lwrctx = NULL;
 516         lwres_gabnresponse_t *by = NULL;
 517         lwres_addr_t *addr;
 518         lwres_result_t lwres;
 519         int result = 0;
 520
 521         lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
 522         if (lwres != LWRES_R_SUCCESS)
 523                 ERR(EAI_FAIL);
 524         (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
 525
 526         if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
 527                 ai = ai_clone(*aip, AF_INET6);
 528                 if (ai == NULL) {
 529                         lwres_freeaddrinfo(*aip);
 530                         ERR(EAI_MEMORY);
 531                 }
 532
 533                 *aip = ai;
 534                 ai->ai_socktype = socktype;
 535                 SIN6(ai->ai_addr)->sin6_port = port;
 536                 memcpy(&SIN6(ai->ai_addr)->sin6_addr, v6_loop, 16);
 537         } else {
 538                 lwres = lwres_getaddrsbyname(lwrctx, hostname,
 539                                              LWRES_ADDRTYPE_V6, &by);
 540                 if (lwres != LWRES_R_SUCCESS) {
 541                         if (lwres == LWRES_R_NOTFOUND)
 542                                 goto cleanup;
 543                         else
 544                                 ERR(EAI_FAIL);
 545                 }
 546                 addr = LWRES_LIST_HEAD(by->addrs);
 547                 while (addr != NULL) {
 548                         ai = ai_clone(*aip, AF_INET6);
 549                         if (ai == NULL) {
 550                                 lwres_freeaddrinfo(*aip);
 551                                 ERR(EAI_MEMORY);
 552                         }
 553                         *aip = ai;
 554                         ai->ai_socktype = socktype;
 555                         SIN6(ai->ai_addr)->sin6_port = port;
 556                         memcpy(&SIN6(ai->ai_addr)->sin6_addr,
 557                                addr->address, 16);
 558                         if (flags & AI_CANONNAME) {
 559                                 ai->ai_canonname = strdup(by->realname);
 560                                 if (ai->ai_canonname == NULL)
 561                                         ERR(EAI_MEMORY);
 562                         }
 563                         addr = LWRES_LIST_NEXT(addr, link);
 564                 }
 565         }
 566  cleanup:
 567         if (by != NULL)
 568                 lwres_gabnresponse_free(lwrctx, &by);
 569         if (lwrctx != NULL) {
 570                 lwres_conf_clear(lwrctx);
 571                 lwres_context_destroy(&lwrctx);
 572         }
 573         return (result);
 574 }
 575
 576 void
 577 lwres_freeaddrinfo(struct addrinfo *ai) {
 578         struct addrinfo *ai_next;
 579
 580         while (ai != NULL) {
 581                 ai_next = ai->ai_next;
 582                 if (ai->ai_addr != NULL)
 583                         free(ai->ai_addr);
 584                 if (ai->ai_canonname)
 585                         free(ai->ai_canonname);
 586                 free(ai);
 587                 ai = ai_next;
 588         }
 589 }
 590
 591 #ifdef AF_LOCAL
 592 static int
 593 get_local(const char *name, int socktype, struct addrinfo **res) {
 594         struct addrinfo *ai;
 595         struct sockaddr_un *sun;
 596
 597         if (socktype == 0)
 598                 return (EAI_SOCKTYPE);
 599
 600         ai = ai_alloc(AF_LOCAL, sizeof(*sun));
 601         if (ai == NULL)
 602                 return (EAI_MEMORY);
 603
 604         sun = SUN(ai->ai_addr);
 605         strncpy(sun->sun_path, name, sizeof(sun->sun_path));
 606
 607         ai->ai_socktype = socktype;
 608         /*
 609          * ai->ai_flags, ai->ai_protocol, ai->ai_canonname,
 610          * and ai->ai_next were initialized to zero.
 611          */
 612
 613         *res = ai;
 614         return (0);
 615 }
 616 #endif
 617
 618 /*
 619  * Allocate an addrinfo structure, and a sockaddr structure
 620  * of the specificed length.  We initialize:
 621  *      ai_addrlen
 622  *      ai_family
 623  *      ai_addr
 624  *      ai_addr->sa_family
 625  *      ai_addr->sa_len (LWRES_PLATFORM_HAVESALEN)
 626  * and everything else is initialized to zero.
 627  */
 628 static struct addrinfo *
 629 ai_alloc(int family, int addrlen) {
 630         struct addrinfo *ai;
 631
 632         ai = (struct addrinfo *)calloc(1, sizeof(*ai));
 633         if (ai == NULL)
 634                 return (NULL);
 635
 636         ai->ai_addr = SA(calloc(1, addrlen));
 637         if (ai->ai_addr == NULL) {
 638                 free(ai);
 639                 return (NULL);
 640         }
 641         ai->ai_addrlen = addrlen;
 642         ai->ai_family = family;
 643         ai->ai_addr->sa_family = family;
 644 #ifdef LWRES_PLATFORM_HAVESALEN
 645         ai->ai_addr->sa_len = addrlen;
 646 #endif
 647         return (ai);
 648 }
 649
 650 static struct addrinfo *
 651 ai_clone(struct addrinfo *oai, int family) {
 652         struct addrinfo *ai;
 653
 654         ai = ai_alloc(family, ((family == AF_INET6) ?
 655             sizeof(struct sockaddr_in6) : sizeof(struct sockaddr_in)));
 656
 657         if (ai == NULL) {
 658                 lwres_freeaddrinfo(oai);
 659                 return (NULL);
 660         }
 661         if (oai == NULL)
 662                 return (ai);
 663
 664         ai->ai_flags = oai->ai_flags;
 665         ai->ai_socktype = oai->ai_socktype;
 666         ai->ai_protocol = oai->ai_protocol;
 667         ai->ai_canonname = NULL;
 668         ai->ai_next = oai;
 669         return (ai);
 670 }
 671
 672 static struct addrinfo *
 673 ai_reverse(struct addrinfo *oai) {
 674         struct addrinfo *nai, *tai;
 675
 676         nai = NULL;
 677
 678         while (oai != NULL) {
 679                 /*
 680                  * Grab one off the old list.
 681                  */
 682                 tai = oai;
 683                 oai = oai->ai_next;
 684                 /*
 685                  * Put it on the front of the new list.
 686                  */
 687                 tai->ai_next = nai;
 688                 nai = tai;
 689         }
 690         return (nai);
 691 }