lib/liblwres/getaddrinfo.c

   1 /*
   2  * Copyright (C) 1999-2001  Internet Software Consortium.
   3  *
   4  * This code is derived from software contributed to Internet Software
   5  * Consortium by Berkeley Software Design, Inc.
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM AND
  12  * BERKELEY SOFTWARE DESIGN, INC DISCLAIM ALL WARRANTIES WITH REGARD TO
  13  * THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
  14  * FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE CONSORTIUM OR BERKELEY
  15  * SOFTWARE DESIGN, INC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
  16  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
  17  * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  18  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  19  * PERFORMANCE OF THIS SOFTWARE.
  20  */
  21
  22 /* $Id: getaddrinfo.c,v 1.1 2004/03/15 20:35:25 as Exp $ */
  23
  24 #include <config.h>
  25
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <stdlib.h>
  29
  30 #include <lwres/lwres.h>
  31 #include <lwres/net.h>
  32 #include <lwres/netdb.h>
  33
  34 #define SA(addr)        ((struct sockaddr *)(addr))
  35 #define SIN(addr)       ((struct sockaddr_in *)(addr))
  36 #define SIN6(addr)      ((struct sockaddr_in6 *)(addr))
  37 #define SUN(addr)       ((struct sockaddr_un *)(addr))
  38
  39 static struct addrinfo
  40         *ai_reverse(struct addrinfo *oai),
  41         *ai_clone(struct addrinfo *oai, int family),
  42         *ai_alloc(int family, int addrlen);
  43 #ifdef AF_LOCAL
  44 static int get_local(const char *name, int socktype, struct addrinfo **res);
  45 #endif
  46
  47 static int add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
  48     int socktype, int port);
  49 static int add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
  50     int socktype, int port);
  51 static void set_order(int, int (**)(const char *, int, struct addrinfo **,
  52          int, int));
  53
  54 #define FOUND_IPV4      0x1
  55 #define FOUND_IPV6      0x2
  56 #define FOUND_MAX       2
  57
  58 #define ISC_AI_MASK (AI_PASSIVE|AI_CANONNAME|AI_NUMERICHOST)
  59
  60 int
  61 lwres_getaddrinfo(const char *hostname, const char *servname,
  62         const struct addrinfo *hints, struct addrinfo **res)
  63 {
  64         struct servent *sp;
  65         const char *proto;
  66         int family, socktype, flags, protocol;
  67         struct addrinfo *ai, *ai_list;
  68         int port, err, i;
  69         int (*net_order[FOUND_MAX+1])(const char *, int, struct addrinfo **,
  70                  int, int);
  71
  72         if (hostname == NULL && servname == NULL)
  73                 return (EAI_NONAME);
  74
  75         proto = NULL;
  76         if (hints != NULL) {
  77                 if ((hints->ai_flags & ~(ISC_AI_MASK)) != 0)
  78                         return (EAI_BADFLAGS);
  79                 if (hints->ai_addrlen || hints->ai_canonname ||
  80                     hints->ai_addr || hints->ai_next) {
  81                         errno = EINVAL;
  82                         return (EAI_SYSTEM);
  83                 }
  84                 family = hints->ai_family;
  85                 socktype = hints->ai_socktype;
  86                 protocol = hints->ai_protocol;
  87                 flags = hints->ai_flags;
  88                 switch (family) {
  89                 case AF_UNSPEC:
  90                         switch (hints->ai_socktype) {
  91                         case SOCK_STREAM:
  92                                 proto = "tcp";
  93                                 break;
  94                         case SOCK_DGRAM:
  95                                 proto = "udp";
  96                                 break;
  97                         }
  98                         break;
  99                 case AF_INET:
 100                 case AF_INET6:
 101                         switch (hints->ai_socktype) {
 102                         case 0:
 103                                 break;
 104                         case SOCK_STREAM:
 105                                 proto = "tcp";
 106                                 break;
 107                         case SOCK_DGRAM:
 108                                 proto = "udp";
 109                                 break;
 110                         case SOCK_RAW:
 111                                 break;
 112                         default:
 113                                 return (EAI_SOCKTYPE);
 114                         }
 115                         break;
 116 #ifdef  AF_LOCAL
 117                 case AF_LOCAL:
 118                         switch (hints->ai_socktype) {
 119                         case 0:
 120                                 break;
 121                         case SOCK_STREAM:
 122                                 break;
 123                         case SOCK_DGRAM:
 124                                 break;
 125                         default:
 126                                 return (EAI_SOCKTYPE);
 127                         }
 128                         break;
 129 #endif
 130                 default:
 131                         return (EAI_FAMILY);
 132                 }
 133         } else {
 134                 protocol = 0;
 135                 family = 0;
 136                 socktype = 0;
 137                 flags = 0;
 138         }
 139
 140 #ifdef  AF_LOCAL
 141         /*
 142          * First, deal with AF_LOCAL.  If the family was not set,
 143          * then assume AF_LOCAL if the first character of the
 144          * hostname/servname is '/'.
 145          */
 146
 147         if (hostname != NULL &&
 148             (family == AF_LOCAL || (family == 0 && *hostname == '/')))
 149                 return (get_local(hostname, socktype, res));
 150
 151         if (servname != NULL &&
 152             (family == AF_LOCAL || (family == 0 && *servname == '/')))
 153                 return (get_local(servname, socktype, res));
 154 #endif
 155
 156         /*
 157          * Ok, only AF_INET and AF_INET6 left.
 158          */
 159         ai_list = NULL;
 160
 161         /*
 162          * First, look up the service name (port) if it was
 163          * requested.  If the socket type wasn't specified, then
 164          * try and figure it out.
 165          */
 166         if (servname != NULL) {
 167                 char *e;
 168
 169                 port = strtol(servname, &e, 10);
 170                 if (*e == '\0') {
 171                         if (socktype == 0)
 172                                 return (EAI_SOCKTYPE);
 173                         if (port < 0 || port > 65535)
 174                                 return (EAI_SERVICE);
 175                         port = htons((unsigned short) port);
 176                 } else {
 177                         sp = getservbyname(servname, proto);
 178                         if (sp == NULL)
 179                                 return (EAI_SERVICE);
 180                         port = sp->s_port;
 181                         if (socktype == 0) {
 182                                 if (strcmp(sp->s_proto, "tcp") == 0)
 183                                         socktype = SOCK_STREAM;
 184                                 else if (strcmp(sp->s_proto, "udp") == 0)
 185                                         socktype = SOCK_DGRAM;
 186                         }
 187                 }
 188         } else
 189                 port = 0;
 190
 191         /*
 192          * Next, deal with just a service name, and no hostname.
 193          * (we verified that one of them was non-null up above).
 194          */
 195         if (hostname == NULL && (flags & AI_PASSIVE) != 0) {
 196                 if (family == AF_INET || family == 0) {
 197                         ai = ai_alloc(AF_INET, sizeof(struct sockaddr_in));
 198                         if (ai == NULL)
 199                                 return (EAI_MEMORY);
 200                         ai->ai_socktype = socktype;
 201                         ai->ai_protocol = protocol;
 202                         SIN(ai->ai_addr)->sin_port = port;
 203                         ai->ai_next = ai_list;
 204                         ai_list = ai;
 205                 }
 206
 207                 if (family == AF_INET6 || family == 0) {
 208                         ai = ai_alloc(AF_INET6, sizeof(struct sockaddr_in6));
 209                         if (ai == NULL) {
 210                                 lwres_freeaddrinfo(ai_list);
 211                                 return (EAI_MEMORY);
 212                         }
 213                         ai->ai_socktype = socktype;
 214                         ai->ai_protocol = protocol;
 215                         SIN6(ai->ai_addr)->sin6_port = port;
 216                         ai->ai_next = ai_list;
 217                         ai_list = ai;
 218                 }
 219
 220                 *res = ai_list;
 221                 return (0);
 222         }
 223
 224         /*
 225          * If the family isn't specified or AI_NUMERICHOST specified,
 226          * check first to see if it is a numeric address.
 227          * Though the gethostbyname2() routine
 228          * will recognize numeric addresses, it will only recognize
 229          * the format that it is being called for.  Thus, a numeric
 230          * AF_INET address will be treated by the AF_INET6 call as
 231          * a domain name, and vice versa.  Checking for both numerics
 232          * here avoids that.
 233          */
 234         if (hostname != NULL &&
 235             (family == 0 || (flags & AI_NUMERICHOST) != 0)) {
 236                 char abuf[sizeof(struct in6_addr)];
 237                 char nbuf[NI_MAXHOST];
 238                 int addrsize, addroff;
 239 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 240                 char *p, *ep;
 241                 char ntmp[NI_MAXHOST];
 242                 lwres_uint32_t scopeid;
 243 #endif
 244
 245 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 246                 /*
 247                  * Scope identifier portion.
 248                  */
 249                 ntmp[0] = '\0';
 250                 if (strchr(hostname, '%') != NULL) {
 251                         strncpy(ntmp, hostname, sizeof(ntmp) - 1);
 252                         ntmp[sizeof(ntmp) - 1] = '\0';
 253                         p = strchr(ntmp, '%');
 254                         ep = NULL;
 255
 256                         /*
 257                          * Vendors may want to support non-numeric
 258                          * scopeid around here.
 259                          */
 260
 261                         if (p != NULL)
 262                                 scopeid = (lwres_uint32_t)strtoul(p + 1,
 263                                                                   &ep, 10);
 264                         if (p != NULL && ep != NULL && ep[0] == '\0')
 265                                 *p = '\0';
 266                         else {
 267                                 ntmp[0] = '\0';
 268                                 scopeid = 0;
 269                         }
 270                 } else
 271                         scopeid = 0;
 272 #endif
 273
 274                if (lwres_net_pton(AF_INET, hostname, (struct in_addr *)abuf)
 275                    == 1)
 276                {
 277                         if (family == AF_INET6) {
 278                                 /*
 279                                  * Convert to a V4 mapped address.
 280                                  */
 281                                 struct in6_addr *a6 = (struct in6_addr *)abuf;
 282                                 memcpy(&a6->s6_addr[12], &a6->s6_addr[0], 4);
 283                                 memset(&a6->s6_addr[10], 0xff, 2);
 284                                 memset(&a6->s6_addr[0], 0, 10);
 285                                 goto inet6_addr;
 286                         }
 287                         addrsize = sizeof(struct in_addr);
 288                         addroff = (char *)(&SIN(0)->sin_addr) - (char *)0;
 289                         family = AF_INET;
 290                         goto common;
 291 #ifdef LWRES_HAVE_SIN6_SCOPE_ID
 292                 } else if (ntmp[0] != '\0' &&
 293                            lwres_net_pton(AF_INET6, ntmp, abuf) == 1)
 294                 {
 295                         if (family && family != AF_INET6)
 296                                 return (EAI_NONAME);
 297                         addrsize = sizeof(struct in6_addr);
 298                         addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
 299                         family = AF_INET6;
 300                         goto common;
 301 #endif
 302                 } else if (lwres_net_pton(AF_INET6, hostname, abuf) == 1) {
 303                         if (family != 0 && family != AF_INET6)
 304                                 return (EAI_NONAME);
 305                 inet6_addr:
 306                         addrsize = sizeof(struct in6_addr);
 307                         addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
 308                         family = AF_INET6;
 309
 310                 common:
 311                         ai = ai_clone(ai_list, family);
 312                         if (ai == NULL)
 313                                 return (EAI_MEMORY);
 314                         ai_list = ai;
 315                         ai->ai_socktype = socktype;
 316                         SIN(ai->ai_addr)->sin_port = port;
 317                         memcpy((char *)ai->ai_addr + addroff, abuf, addrsize);
 318                         if (flags & AI_CANONNAME) {
 319 #if defined(LWRES_HAVE_SIN6_SCOPE_ID)
 320                                 if (ai->ai_family == AF_INET6)
 321                                         SIN6(ai->ai_addr)->sin6_scope_id =
 322                                                                         scopeid;
 323 #endif
 324                                 if (lwres_getnameinfo(ai->ai_addr,
 325                                     ai->ai_addrlen, nbuf, sizeof(nbuf),
 326                                                       NULL, 0,
 327                                                       NI_NUMERICHOST) == 0) {
 328                                         ai->ai_canonname = strdup(nbuf);
 329                                         if (ai->ai_canonname == NULL)
 330                                                 return (EAI_MEMORY);
 331                                 } else {
 332                                         /* XXX raise error? */
 333                                         ai->ai_canonname = NULL;
 334                                 }
 335                         }
 336                         goto done;
 337                 } else if ((flags & AI_NUMERICHOST) != 0) {
 338                         return (EAI_NONAME);
 339                 }
 340         }
 341
 342         set_order(family, net_order);
 343         for (i = 0; i < FOUND_MAX; i++) {
 344                 if (net_order[i] == NULL)
 345                         break;
 346                 err = (net_order[i])(hostname, flags, &ai_list,
 347                                      socktype, port);
 348                 if (err != 0)
 349                         return (err);
 350         }
 351
 352         if (ai_list == NULL)
 353                 return (EAI_NODATA);
 354
 355 done:
 356         ai_list = ai_reverse(ai_list);
 357
 358         *res = ai_list;
 359         return (0);
 360 }
 361
 362 static char *
 363 lwres_strsep(char **stringp, const char *delim) {
 364         char *string = *stringp;
 365         char *s;
 366         const char *d;
 367         char sc, dc;
 368
 369         if (string == NULL)
 370                 return (NULL);
 371
 372         for (s = string; *s != '\0'; s++) {
 373                 sc = *s;
 374                 for (d = delim; (dc = *d) != '\0'; d++)
 375                         if (sc == dc) {
 376                                 *s++ = '\0';
 377                                 *stringp = s;
 378                                 return (string);
 379                         }
 380         }
 381         *stringp = NULL;
 382         return (string);
 383 }
 384
 385 static void
 386 set_order(int family, int (**net_order)(const char *, int, struct addrinfo **,
 387                                         int, int))
 388 {
 389         char *order, *tok;
 390         int found;
 391
 392         if (family) {
 393                 switch (family) {
 394                 case AF_INET:
 395                         *net_order++ = add_ipv4;
 396                         break;
 397                 case AF_INET6:
 398                         *net_order++ = add_ipv6;
 399                         break;
 400                 }
 401         } else {
 402                 order = getenv("NET_ORDER");
 403                 found = 0;
 404                 while (order != NULL) {
 405                         /*
 406                          * We ignore any unknown names.
 407                          */
 408                         tok = lwres_strsep(&order, ":");
 409                         if (strcasecmp(tok, "inet6") == 0) {
 410                                 if ((found & FOUND_IPV6) == 0)
 411                                         *net_order++ = add_ipv6;
 412                                 found |= FOUND_IPV6;
 413                         } else if (strcasecmp(tok, "inet") == 0 ||
 414                             strcasecmp(tok, "inet4") == 0) {
 415                                 if ((found & FOUND_IPV4) == 0)
 416                                         *net_order++ = add_ipv4;
 417                                 found |= FOUND_IPV4;
 418                         }
 419                 }
 420
 421                 /*
 422                  * Add in anything that we didn't find.
 423                  */
 424                 if ((found & FOUND_IPV4) == 0)
 425                         *net_order++ = add_ipv4;
 426                 if ((found & FOUND_IPV6) == 0)
 427                         *net_order++ = add_ipv6;
 428         }
 429         *net_order = NULL;
 430         return;
 431 }
 432
 433 static char v4_loop[4] = { 127, 0, 0, 1 };
 434
 435 /*
 436  * The test against 0 is there to keep the Solaris compiler
 437  * from complaining about "end-of-loop code not reached".
 438  */
 439 #define ERR(code) \
 440         do { result = (code);                   \
 441                 if (result != 0) goto cleanup;  \
 442         } while (0)
 443
 444 static int
 445 add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
 446         int socktype, int port)
 447 {
 448         struct addrinfo *ai;
 449         lwres_context_t *lwrctx = NULL;
 450         lwres_gabnresponse_t *by = NULL;
 451         lwres_addr_t *addr;
 452         lwres_result_t lwres;
 453         int result = 0;
 454
 455         lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
 456         if (lwres != LWRES_R_SUCCESS)
 457                 ERR(EAI_FAIL);
 458         (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
 459         if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
 460                 ai = ai_clone(*aip, AF_INET);
 461                 if (ai == NULL) {
 462                         lwres_freeaddrinfo(*aip);
 463                         ERR(EAI_MEMORY);
 464                 }
 465
 466                 *aip = ai;
 467                 ai->ai_socktype = socktype;
 468                 SIN(ai->ai_addr)->sin_port = port;
 469                 memcpy(&SIN(ai->ai_addr)->sin_addr, v4_loop, 4);
 470         } else {
 471                 lwres = lwres_getaddrsbyname(lwrctx, hostname,
 472                                              LWRES_ADDRTYPE_V4, &by);
 473                 if (lwres != LWRES_R_SUCCESS) {
 474                         if (lwres == LWRES_R_NOTFOUND)
 475                                 goto cleanup;
 476                         else
 477                                 ERR(EAI_FAIL);
 478                 }
 479                 addr = LWRES_LIST_HEAD(by->addrs);
 480                 while (addr != NULL) {
 481                         ai = ai_clone(*aip, AF_INET);
 482                         if (ai == NULL) {
 483                                 lwres_freeaddrinfo(*aip);
 484                                 ERR(EAI_MEMORY);
 485                         }
 486                         *aip = ai;
 487                         ai->ai_socktype = socktype;
 488                         SIN(ai->ai_addr)->sin_port = port;
 489                         memcpy(&SIN(ai->ai_addr)->sin_addr,
 490                                addr->address, 4);
 491                         if (flags & AI_CANONNAME) {
 492                                 ai->ai_canonname = strdup(by->realname);
 493                                 if (ai->ai_canonname == NULL)
 494                                         ERR(EAI_MEMORY);
 495                         }
 496                         addr = LWRES_LIST_NEXT(addr, link);
 497                 }
 498         }
 499  cleanup:
 500         if (by != NULL)
 501                 lwres_gabnresponse_free(lwrctx, &by);
 502         if (lwrctx != NULL) {
 503                 lwres_conf_clear(lwrctx);
 504                 lwres_context_destroy(&lwrctx);
 505         }
 506         return (result);
 507 }
 508
 509 static char v6_loop[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 };
 510
 511 static int
 512 add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
 513          int socktype, int port)
 514 {
 515         struct addrinfo *ai;
 516         lwres_context_t *lwrctx = NULL;
 517         lwres_gabnresponse_t *by = NULL;
 518         lwres_addr_t *addr;
 519         lwres_result_t lwres;
 520         int result = 0;
 521
 522         lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
 523         if (lwres != LWRES_R_SUCCESS)
 524                 ERR(EAI_FAIL);
 525         (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
 526
 527         if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
 528                 ai = ai_clone(*aip, AF_INET6);
 529                 if (ai == NULL) {
 530                         lwres_freeaddrinfo(*aip);
 531                         ERR(EAI_MEMORY);
 532                 }
 533
 534                 *aip = ai;
 535                 ai->ai_socktype = socktype;
 536                 SIN6(ai->ai_addr)->sin6_port = port;
 537                 memcpy(&SIN6(ai->ai_addr)->sin6_addr, v6_loop, 16);
 538         } else {
 539                 lwres = lwres_getaddrsbyname(lwrctx, hostname,
 540                                              LWRES_ADDRTYPE_V6, &by);
 541                 if (lwres != LWRES_R_SUCCESS) {
 542                         if (lwres == LWRES_R_NOTFOUND)
 543                                 goto cleanup;
 544                         else
 545                                 ERR(EAI_FAIL);
 546                 }
 547                 addr = LWRES_LIST_HEAD(by->addrs);
 548                 while (addr != NULL) {
 549                         ai = ai_clone(*aip, AF_INET6);
 550                         if (ai == NULL) {
 551                                 lwres_freeaddrinfo(*aip);
 552                                 ERR(EAI_MEMORY);
 553                         }
 554                         *aip = ai;
 555                         ai->ai_socktype = socktype;
 556                         SIN6(ai->ai_addr)->sin6_port = port;
 557                         memcpy(&SIN6(ai->ai_addr)->sin6_addr,
 558                                addr->address, 16);
 559                         if (flags & AI_CANONNAME) {
 560                                 ai->ai_canonname = strdup(by->realname);
 561                                 if (ai->ai_canonname == NULL)
 562                                         ERR(EAI_MEMORY);
 563                         }
 564                         addr = LWRES_LIST_NEXT(addr, link);
 565                 }
 566         }
 567  cleanup:
 568         if (by != NULL)
 569                 lwres_gabnresponse_free(lwrctx, &by);
 570         if (lwrctx != NULL) {
 571                 lwres_conf_clear(lwrctx);
 572                 lwres_context_destroy(&lwrctx);
 573         }
 574         return (result);
 575 }
 576
 577 void
 578 lwres_freeaddrinfo(struct addrinfo *ai) {
 579         struct addrinfo *ai_next;
 580
 581         while (ai != NULL) {
 582                 ai_next = ai->ai_next;
 583                 if (ai->ai_addr != NULL)
 584                         free(ai->ai_addr);
 585                 if (ai->ai_canonname)
 586                         free(ai->ai_canonname);
 587                 free(ai);
 588                 ai = ai_next;
 589         }
 590 }
 591
 592 #ifdef AF_LOCAL
 593 static int
 594 get_local(const char *name, int socktype, struct addrinfo **res) {
 595         struct addrinfo *ai;
 596         struct sockaddr_un *sun;
 597
 598         if (socktype == 0)
 599                 return (EAI_SOCKTYPE);
 600
 601         ai = ai_alloc(AF_LOCAL, sizeof(*sun));
 602         if (ai == NULL)
 603                 return (EAI_MEMORY);
 604
 605         sun = SUN(ai->ai_addr);
 606         strncpy(sun->sun_path, name, sizeof(sun->sun_path));
 607
 608         ai->ai_socktype = socktype;
 609         /*
 610          * ai->ai_flags, ai->ai_protocol, ai->ai_canonname,
 611          * and ai->ai_next were initialized to zero.
 612          */
 613
 614         *res = ai;
 615         return (0);
 616 }
 617 #endif
 618
 619 /*
 620  * Allocate an addrinfo structure, and a sockaddr structure
 621  * of the specificed length.  We initialize:
 622  *      ai_addrlen
 623  *      ai_family
 624  *      ai_addr
 625  *      ai_addr->sa_family
 626  *      ai_addr->sa_len (LWRES_PLATFORM_HAVESALEN)
 627  * and everything else is initialized to zero.
 628  */
 629 static struct addrinfo *
 630 ai_alloc(int family, int addrlen) {
 631         struct addrinfo *ai;
 632
 633         ai = (struct addrinfo *)calloc(1, sizeof(*ai));
 634         if (ai == NULL)
 635                 return (NULL);
 636
 637         ai->ai_addr = SA(calloc(1, addrlen));
 638         if (ai->ai_addr == NULL) {
 639                 free(ai);
 640                 return (NULL);
 641         }
 642         ai->ai_addrlen = addrlen;
 643         ai->ai_family = family;
 644         ai->ai_addr->sa_family = family;
 645 #ifdef LWRES_PLATFORM_HAVESALEN
 646         ai->ai_addr->sa_len = addrlen;
 647 #endif
 648         return (ai);
 649 }
 650
 651 static struct addrinfo *
 652 ai_clone(struct addrinfo *oai, int family) {
 653         struct addrinfo *ai;
 654
 655         ai = ai_alloc(family, ((family == AF_INET6) ?
 656             sizeof(struct sockaddr_in6) : sizeof(struct sockaddr_in)));
 657
 658         if (ai == NULL) {
 659                 lwres_freeaddrinfo(oai);
 660                 return (NULL);
 661         }
 662         if (oai == NULL)
 663                 return (ai);
 664
 665         ai->ai_flags = oai->ai_flags;
 666         ai->ai_socktype = oai->ai_socktype;
 667         ai->ai_protocol = oai->ai_protocol;
 668         ai->ai_canonname = NULL;
 669         ai->ai_next = oai;
 670         return (ai);
 671 }
 672
 673 static struct addrinfo *
 674 ai_reverse(struct addrinfo *oai) {
 675         struct addrinfo *nai, *tai;
 676
 677         nai = NULL;
 678
 679         while (oai != NULL) {
 680                 /*
 681                  * Grab one off the old list.
 682                  */
 683                 tai = oai;
 684                 oai = oai->ai_next;
 685                 /*
 686                  * Put it on the front of the new list.
 687                  */
 688                 tai->ai_next = nai;
 689                 nai = tai;
 690         }
 691         return (nai);
 692 }