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getaddrinfo.c

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * "#ifdef FAITH" part is local hack for supporting IPv4-v6 translator.
 *
 * Issues to be discussed:
 * - Thread safe-ness must be checked.
 * - Return values.  There are nonstandard return values defined and used
 *   in the source code.  This is because RFC2553 is silent about which error
 *   code must be returned for which situation.
 * Note:
 * - We use getipnodebyname() just for thread-safeness.  There's no intent
 *   to let it do PF_UNSPEC (actually we never pass PF_UNSPEC to
 *   getipnodebyname().
 * - The code filters out AFs that are not supported by the kernel,
 *   when globbing NULL hostname (to loopback, or wildcard).  Is it the right
 *   thing to do?  What is the relationship with post-RFC2553 AI_ADDRCONFIG
 *   in ai_flags?
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif 

#ifndef lint
static const char rcsid[] _U_ =
     "@(#) $Header$";
#endif

#include <pcap-stdinc.h>
#if 0
#include <sys/sysctl.h>
#endif
#ifndef __MINGW32__
#include <arpa/nameser.h>
#endif
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <ctype.h>
#include <stdio.h>
#include <errno.h>

#ifndef HAVE_PORTABLE_PROTOTYPE
#include "cdecl_ext.h"
#endif 

#ifndef HAVE_U_INT32_T
#include "bittypes.h"
#endif 

#ifndef HAVE_SOCKADDR_STORAGE
#ifndef __MINGW32__
#include "sockstorage.h"
#endif
#endif 

#ifdef NEED_ADDRINFO_H
#include "addrinfo.h"
#ifdef WIN32
#include "IP6_misc.h"
#endif
#endif


#if defined(__KAME__) && defined(INET6)
# define FAITH
#endif

#define SUCCESS 0
#define ANY 0
#define YES 1
#define NO  0

#ifdef FAITH
static int translate = NO;
static struct in6_addr faith_prefix = IN6ADDR_ANY_INIT;
#endif

static const char in_addrany[] = { 0, 0, 0, 0 };
static const char in6_addrany[] = {
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
static const char in_loopback[] = { 127, 0, 0, 1 }; 
static const char in6_loopback[] = {
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
};

struct sockinet {
      u_char      si_len;
      u_char      si_family;
      u_short     si_port;
      u_int32_t si_scope_id;
};

static const struct afd {
      int a_af;
      int a_addrlen;
      int a_socklen;
      int a_off;
      const char *a_addrany;
      const char *a_loopback; 
      int a_scoped;
} afdl [] = {
#ifdef INET6
      {PF_INET6, sizeof(struct in6_addr),
       sizeof(struct sockaddr_in6),
       offsetof(struct sockaddr_in6, sin6_addr),
       in6_addrany, in6_loopback, 1},
#endif
      {PF_INET, sizeof(struct in_addr),
       sizeof(struct sockaddr_in),
       offsetof(struct sockaddr_in, sin_addr),
       in_addrany, in_loopback, 0},
      {0, 0, 0, 0, NULL, NULL, 0},
};

struct explore {
      int e_af;
      int e_socktype;
      int e_protocol;
      const char *e_protostr;
      int e_wild;
#define WILD_AF(ex)           ((ex)->e_wild & 0x01)
#define WILD_SOCKTYPE(ex)     ((ex)->e_wild & 0x02)
#define WILD_PROTOCOL(ex)     ((ex)->e_wild & 0x04)
};

static const struct explore explore[] = {
#if 0
      { PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
#endif
#ifdef INET6
      { PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
      { PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
      { PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
#endif
      { PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
      { PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
      { PF_INET, SOCK_RAW, ANY, NULL, 0x05 },
      { -1, 0, 0, NULL, 0 },
};

#ifdef INET6
#define PTON_MAX  16
#else
#define PTON_MAX  4
#endif


static int str_isnumber __P((const char *));
static int explore_fqdn __P((const struct addrinfo *, const char *,
      const char *, struct addrinfo **));
static int explore_null __P((const struct addrinfo *, const char *,
      const char *, struct addrinfo **));
static int explore_numeric __P((const struct addrinfo *, const char *,
      const char *, struct addrinfo **));
static int explore_numeric_scope __P((const struct addrinfo *, const char *,
      const char *, struct addrinfo **));
static int get_name __P((const char *, const struct afd *, struct addrinfo **,
      char *, const struct addrinfo *, const char *));
static int get_canonname __P((const struct addrinfo *,
      struct addrinfo *, const char *));
static struct addrinfo *get_ai __P((const struct addrinfo *,
      const struct afd *, const char *));
static int get_portmatch __P((const struct addrinfo *, const char *));
static int get_port __P((struct addrinfo *, const char *, int));
static const struct afd *find_afd __P((int));

static char *ai_errlist[] = {
      "Success",
      "Address family for hostname not supported",    /* EAI_ADDRFAMILY */
      "Temporary failure in name resolution",         /* EAI_AGAIN      */
      "Invalid value for ai_flags",                   /* EAI_BADFLAGS   */
      "Non-recoverable failure in name resolution",   /* EAI_FAIL       */
      "ai_family not supported",                /* EAI_FAMILY     */
      "Memory allocation failure",              /* EAI_MEMORY     */
      "No address associated with hostname",          /* EAI_NODATA     */
      "hostname nor servname provided, or not known", /* EAI_NONAME     */
      "servname not supported for ai_socktype", /* EAI_SERVICE    */
      "ai_socktype not supported",              /* EAI_SOCKTYPE   */
      "System error returned in errno",         /* EAI_SYSTEM     */
      "Invalid value for hints",                /* EAI_BADHINTS     */
      "Resolved protocol is unknown",                 /* EAI_PROTOCOL   */
      "Unknown error",                    /* EAI_MAX        */
};

/* XXX macros that make external reference is BAD. */

#define GET_AI(ai, afd, addr) \
do { \
      /* external reference: pai, error, and label free */ \
      (ai) = get_ai(pai, (afd), (addr)); \
      if ((ai) == NULL) { \
            error = EAI_MEMORY; \
            goto free; \
      } \
} while (0)

#define GET_PORT(ai, serv) \
do { \
      /* external reference: error and label free */ \
      error = get_port((ai), (serv), 0); \
      if (error != 0) \
            goto free; \
} while (0)

#define GET_CANONNAME(ai, str) \
do { \
      /* external reference: pai, error and label free */ \
      error = get_canonname(pai, (ai), (str)); \
      if (error != 0) \
            goto free; \
} while (0)

#define ERR(err) \
do { \
      /* external reference: error, and label bad */ \
      error = (err); \
      goto bad; \
} while (0)

#define MATCH_FAMILY(x, y, w) \
      ((x) == (y) || ((w) && ((x) == PF_UNSPEC || (y) == PF_UNSPEC)))
#define MATCH(x, y, w) \
      ((x) == (y) || ((w) && ((x) == ANY || (y) == ANY)))

char *
gai_strerror(ecode)
      int ecode;
{
      if (ecode < 0 || ecode > EAI_MAX)
            ecode = EAI_MAX;
      return ai_errlist[ecode];
}

void
freeaddrinfo(ai)
      struct addrinfo *ai;
{
      struct addrinfo *next;

      do {
            next = ai->ai_next;
            if (ai->ai_canonname)
                  free(ai->ai_canonname);
            /* no need to free(ai->ai_addr) */
            free(ai);
      } while ((ai = next) != NULL);
}

static int
str_isnumber(p)
      const char *p;
{
      char *q = (char *)p;
      while (*q) {
            if (! isdigit(*q))
                  return NO;
            q++;
      }
      return YES;
}

int
getaddrinfo(hostname, servname, hints, res)
      const char *hostname, *servname;
      const struct addrinfo *hints;
      struct addrinfo **res;
{
      struct addrinfo sentinel;
      struct addrinfo *cur;
      int error = 0;
      struct addrinfo ai;
      struct addrinfo ai0;
      struct addrinfo *pai;
      const struct afd *afd;
      const struct explore *ex;

#ifdef FAITH
      static int firsttime = 1;

      if (firsttime) {
            /* translator hack */
            char *q = getenv("GAI");
            if (q && inet_pton(AF_INET6, q, &faith_prefix) == 1)
                  translate = YES;
            firsttime = 0;
      }
#endif

      sentinel.ai_next = NULL;
      cur = &sentinel;
      pai = &ai;
      pai->ai_flags = 0;
      pai->ai_family = PF_UNSPEC;
      pai->ai_socktype = ANY;
      pai->ai_protocol = ANY;
      pai->ai_addrlen = 0;
      pai->ai_canonname = NULL;
      pai->ai_addr = NULL;
      pai->ai_next = NULL;
      
      if (hostname == NULL && servname == NULL)
            return EAI_NONAME;
      if (hints) {
            /* error check for hints */
            if (hints->ai_addrlen || hints->ai_canonname ||
                hints->ai_addr || hints->ai_next)
                  ERR(EAI_BADHINTS); /* xxx */
            if (hints->ai_flags & ~AI_MASK)
                  ERR(EAI_BADFLAGS);
            switch (hints->ai_family) {
            case PF_UNSPEC:
            case PF_INET:
#ifdef INET6
            case PF_INET6:
#endif
                  break;
            default:
                  ERR(EAI_FAMILY);
            }
            memcpy(pai, hints, sizeof(*pai));

            /*
             * if both socktype/protocol are specified, check if they
             * are meaningful combination.
             */
            if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
                  for (ex = explore; ex->e_af >= 0; ex++) {
                        if (pai->ai_family != ex->e_af)
                              continue;
                        if (ex->e_socktype == ANY)
                              continue;
                        if (ex->e_protocol == ANY)
                              continue;
                        if (pai->ai_socktype == ex->e_socktype
                         && pai->ai_protocol != ex->e_protocol) {
                              ERR(EAI_BADHINTS);
                        }
                  }
            }
      }

      /*
       * check for special cases.  (1) numeric servname is disallowed if
       * socktype/protocol are left unspecified. (2) servname is disallowed
       * for raw and other inet{,6} sockets.
       */
      if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
#ifdef PF_INET6
       || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
#endif
          ) {
            ai0 = *pai;

            if (pai->ai_family == PF_UNSPEC) {
#ifdef PF_INET6
                  pai->ai_family = PF_INET6;
#else
                  pai->ai_family = PF_INET;
#endif
            }
            error = get_portmatch(pai, servname);
            if (error)
                  ERR(error);

            *pai = ai0;
      }

      ai0 = *pai;

      /* NULL hostname, or numeric hostname */
      for (ex = explore; ex->e_af >= 0; ex++) {
            *pai = ai0;

            if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
                  continue;
            if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex)))
                  continue;
            if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex)))
                  continue;

            if (pai->ai_family == PF_UNSPEC)
                  pai->ai_family = ex->e_af;
            if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
                  pai->ai_socktype = ex->e_socktype;
            if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
                  pai->ai_protocol = ex->e_protocol;

            if (hostname == NULL)
                  error = explore_null(pai, hostname, servname, &cur->ai_next);
            else
                  error = explore_numeric_scope(pai, hostname, servname, &cur->ai_next);

            if (error)
                  goto free;

            while (cur && cur->ai_next)
                  cur = cur->ai_next;
      }

      /*
       * XXX
       * If numreic representation of AF1 can be interpreted as FQDN
       * representation of AF2, we need to think again about the code below.
       */
      if (sentinel.ai_next)
            goto good;

      if (pai->ai_flags & AI_NUMERICHOST)
            ERR(EAI_NONAME);
      if (hostname == NULL)
            ERR(EAI_NONAME);

      /*
       * hostname as alphabetical name.
       * we would like to prefer AF_INET6 than AF_INET, so we'll make a
       * outer loop by AFs.
       */
      for (afd = afdl; afd->a_af; afd++) {
            *pai = ai0;

            if (!MATCH_FAMILY(pai->ai_family, afd->a_af, 1))
                  continue;

            for (ex = explore; ex->e_af >= 0; ex++) {
                  *pai = ai0;

                  if (pai->ai_family == PF_UNSPEC)
                        pai->ai_family = afd->a_af;

                  if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
                        continue;
                  if (!MATCH(pai->ai_socktype, ex->e_socktype,
                              WILD_SOCKTYPE(ex))) {
                        continue;
                  }
                  if (!MATCH(pai->ai_protocol, ex->e_protocol,
                              WILD_PROTOCOL(ex))) {
                        continue;
                  }

                  if (pai->ai_family == PF_UNSPEC)
                        pai->ai_family = ex->e_af;
                  if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
                        pai->ai_socktype = ex->e_socktype;
                  if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
                        pai->ai_protocol = ex->e_protocol;

                  error = explore_fqdn(pai, hostname, servname,
                        &cur->ai_next);

                  while (cur && cur->ai_next)
                        cur = cur->ai_next;
            }
      }

      /* XXX */
      if (sentinel.ai_next)
            error = 0;

      if (error)
            goto free;
      if (error == 0) {
            if (sentinel.ai_next) {
 good:
                  *res = sentinel.ai_next;
                  return SUCCESS;
            } else
                  error = EAI_FAIL;
      }
 free:
 bad:
      if (sentinel.ai_next)
            freeaddrinfo(sentinel.ai_next);
      *res = NULL;
      return error;
}

/*
 * FQDN hostname, DNS lookup
 */
static int
explore_fqdn(pai, hostname, servname, res)
      const struct addrinfo *pai;
      const char *hostname;
      const char *servname;
      struct addrinfo **res;
{
      struct hostent *hp;
      int h_error;
      int af;
      char **aplist = NULL, *apbuf = NULL;
      char *ap;
      struct addrinfo sentinel, *cur;
      int i;
#ifndef USE_GETIPNODEBY
      int naddrs;
#endif
      const struct afd *afd;
      int error;

      *res = NULL;
      sentinel.ai_next = NULL;
      cur = &sentinel;

      /*
       * Do not filter unsupported AFs here.  We need to honor content of
       * databases (/etc/hosts, DNS and others).  Otherwise we cannot
       * replace gethostbyname() by getaddrinfo().
       */

      /*
       * if the servname does not match socktype/protocol, ignore it.
       */
      if (get_portmatch(pai, servname) != 0)
            return 0;

      afd = find_afd(pai->ai_family);

      /*
       * post-RFC2553: should look at (pai->ai_flags & AI_ADDRCONFIG)
       * rather than hardcoding it.  we may need to add AI_ADDRCONFIG
       * handling code by ourselves in case we don't have getipnodebyname().
       */
#ifdef USE_GETIPNODEBY
      hp = getipnodebyname(hostname, pai->ai_family, AI_ADDRCONFIG, &h_error);
#else
#ifdef HAVE_GETHOSTBYNAME2
      hp = gethostbyname2(hostname, pai->ai_family);
#else
      if (pai->ai_family != AF_INET)
            return 0;
      hp = gethostbyname(hostname);
#ifdef HAVE_H_ERRNO
      h_error = h_errno;
#else
      h_error = EINVAL;
#endif
#endif /*HAVE_GETHOSTBYNAME2*/
#endif /*USE_GETIPNODEBY*/

      if (hp == NULL) {
            switch (h_error) {
            case HOST_NOT_FOUND:
            case NO_DATA:
                  error = EAI_NODATA;
                  break;
            case TRY_AGAIN:
                  error = EAI_AGAIN;
                  break;
            case NO_RECOVERY:
            case NETDB_INTERNAL:
            default:
                  error = EAI_FAIL;
                  break;
            }
      } else if ((hp->h_name == NULL) || (hp->h_name[0] == 0)
                  || (hp->h_addr_list[0] == NULL)) {
#ifdef USE_GETIPNODEBY
            freehostent(hp);
#endif
            hp = NULL;
            error = EAI_FAIL;
      }

      if (hp == NULL)
            goto free;

#ifdef USE_GETIPNODEBY
      aplist = hp->h_addr_list;
#else
      /*
       * hp will be overwritten if we use gethostbyname2().
       * always deep copy for simplification.
       */
      for (naddrs = 0; hp->h_addr_list[naddrs] != NULL; naddrs++)
            ;
      naddrs++;
      aplist = (char **)malloc(sizeof(aplist[0]) * naddrs);
      apbuf = (char *)malloc(hp->h_length * naddrs);
      if (aplist == NULL || apbuf == NULL) {
            error = EAI_MEMORY;
            goto free;
      }
      memset(aplist, 0, sizeof(aplist[0]) * naddrs);
      for (i = 0; i < naddrs; i++) {
            if (hp->h_addr_list[i] == NULL) {
                  aplist[i] = NULL;
                  continue;
            }
            memcpy(&apbuf[i * hp->h_length], hp->h_addr_list[i],
                  hp->h_length);
            aplist[i] = &apbuf[i * hp->h_length];
      }
#endif

      for (i = 0; aplist[i] != NULL; i++) {
            af = hp->h_addrtype;
            ap = aplist[i];
#ifdef AF_INET6
            if (af == AF_INET6
             && IN6_IS_ADDR_V4MAPPED((struct in6_addr *)ap)) {
                  af = AF_INET;
                  ap = ap + sizeof(struct in6_addr)
                        - sizeof(struct in_addr);
            }
#endif

            if (af != pai->ai_family)
                  continue;

            if ((pai->ai_flags & AI_CANONNAME) == 0) {
                  GET_AI(cur->ai_next, afd, ap);
                  GET_PORT(cur->ai_next, servname);
            } else {
                  /*
                   * if AI_CANONNAME and if reverse lookup
                   * fail, return ai anyway to pacify
                   * calling application.
                   *
                   * XXX getaddrinfo() is a name->address
                   * translation function, and it looks
                   * strange that we do addr->name
                   * translation here.
                   */
                  get_name(ap, afd, &cur->ai_next,
                        ap, pai, servname);
            }

            while (cur && cur->ai_next)
                  cur = cur->ai_next;
      }

      *res = sentinel.ai_next;
      return 0;

free:
#ifdef USE_GETIPNODEBY
      if (hp)
            freehostent(hp);
#endif
      if (aplist)
            free(aplist);
      if (apbuf)
            free(apbuf);
      if (sentinel.ai_next)
            freeaddrinfo(sentinel.ai_next);
      return error;
}

/*
 * hostname == NULL.
 * passive socket -> anyaddr (0.0.0.0 or ::)
 * non-passive socket -> localhost (127.0.0.1 or ::1)
 */
static int
explore_null(pai, hostname, servname, res)
      const struct addrinfo *pai;
      const char *hostname;
      const char *servname;
      struct addrinfo **res;
{
      int s;
      const struct afd *afd;
      struct addrinfo *cur;
      struct addrinfo sentinel;
      int error;

      *res = NULL;
      sentinel.ai_next = NULL;
      cur = &sentinel;

      /*
       * filter out AFs that are not supported by the kernel
       * XXX errno?
       */
      s = socket(pai->ai_family, SOCK_DGRAM, 0);
      if (s < 0) {
            if (errno != EMFILE)
                  return 0;
      } else
            close(s);

      /*
       * if the servname does not match socktype/protocol, ignore it.
       */
      if (get_portmatch(pai, servname) != 0)
            return 0;

      afd = find_afd(pai->ai_family);

      if (pai->ai_flags & AI_PASSIVE) {
            GET_AI(cur->ai_next, afd, afd->a_addrany);
            /* xxx meaningless?
             * GET_CANONNAME(cur->ai_next, "anyaddr");
             */
            GET_PORT(cur->ai_next, servname);
      } else {
            GET_AI(cur->ai_next, afd, afd->a_loopback);
            /* xxx meaningless?
             * GET_CANONNAME(cur->ai_next, "localhost");
             */
            GET_PORT(cur->ai_next, servname);
      }
      cur = cur->ai_next;

      *res = sentinel.ai_next;
      return 0;

free:
      if (sentinel.ai_next)
            freeaddrinfo(sentinel.ai_next);
      return error;
}

/*
 * numeric hostname
 */
static int
explore_numeric(pai, hostname, servname, res)
      const struct addrinfo *pai;
      const char *hostname;
      const char *servname;
      struct addrinfo **res;
{
      const struct afd *afd;
      struct addrinfo *cur;
      struct addrinfo sentinel;
      int error;
      char pton[PTON_MAX];
      int flags;

      *res = NULL;
      sentinel.ai_next = NULL;
      cur = &sentinel;

      /*
       * if the servname does not match socktype/protocol, ignore it.
       */
      if (get_portmatch(pai, servname) != 0)
            return 0;

      afd = find_afd(pai->ai_family);
      flags = pai->ai_flags;

      if (inet_pton(afd->a_af, hostname, pton) == 1) {
            u_int32_t v4a;
#ifdef INET6
            u_char pfx;
#endif

            switch (afd->a_af) {
            case AF_INET:
                  v4a = (u_int32_t)ntohl(((struct in_addr *)pton)->s_addr);
                  if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
                        flags &= ~AI_CANONNAME;
                  v4a >>= IN_CLASSA_NSHIFT;
                  if (v4a == 0 || v4a == IN_LOOPBACKNET)
                        flags &= ~AI_CANONNAME;
                  break;
#ifdef INET6
            case AF_INET6:
                  pfx = ((struct in6_addr *)pton)->s6_addr[0];
                  if (pfx == 0 || pfx == 0xfe || pfx == 0xff)
                        flags &= ~AI_CANONNAME;
                  break;
#endif
            }

            if (pai->ai_family == afd->a_af ||
                pai->ai_family == PF_UNSPEC /*?*/) {
                  if ((flags & AI_CANONNAME) == 0) {
                        GET_AI(cur->ai_next, afd, pton);
                        GET_PORT(cur->ai_next, servname);
                  } else {
                        /*
                         * if AI_CANONNAME and if reverse lookup
                         * fail, return ai anyway to pacify
                         * calling application.
                         *
                         * XXX getaddrinfo() is a name->address
                         * translation function, and it looks
                         * strange that we do addr->name
                         * translation here.
                         */
                        get_name(pton, afd, &cur->ai_next,
                              pton, pai, servname);
                  }
                  while (cur && cur->ai_next)
                        cur = cur->ai_next;
            } else 
                  ERR(EAI_FAMILY);  /*xxx*/
      }

      *res = sentinel.ai_next;
      return 0;

free:
bad:
      if (sentinel.ai_next)
            freeaddrinfo(sentinel.ai_next);
      return error;
}

/*
 * numeric hostname with scope
 */
static int
explore_numeric_scope(pai, hostname, servname, res)
      const struct addrinfo *pai;
      const char *hostname;
      const char *servname;
      struct addrinfo **res;
{
#ifndef SCOPE_DELIMITER
      return explore_numeric(pai, hostname, servname, res);
#else
      const struct afd *afd;
      struct addrinfo *cur;
      int error;
      char *cp, *hostname2 = NULL;
      int scope;
      struct sockaddr_in6 *sin6;

      /*
       * if the servname does not match socktype/protocol, ignore it.
       */
      if (get_portmatch(pai, servname) != 0)
            return 0;

      afd = find_afd(pai->ai_family);
      if (!afd->a_scoped)
            return explore_numeric(pai, hostname, servname, res);

      cp = strchr(hostname, SCOPE_DELIMITER);
      if (cp == NULL)
            return explore_numeric(pai, hostname, servname, res);

      /*
       * Handle special case of <scoped_address><delimiter><scope id>
       */
      hostname2 = strdup(hostname);
      if (hostname2 == NULL)
            return EAI_MEMORY;
      /* terminate at the delimiter */
      hostname2[cp - hostname] = '\0';

      cp++;
      switch (pai->ai_family) {
#ifdef INET6
      case AF_INET6:
            scope = if_nametoindex(cp);
            if (scope == 0) {
                  free(hostname2);
                  return (EAI_NONAME);
            }
            break;
#endif
      }

      error = explore_numeric(pai, hostname2, servname, res);
      if (error == 0) {
            for (cur = *res; cur; cur = cur->ai_next) {
                  if (cur->ai_family != AF_INET6)
                        continue;
                  sin6 = (struct sockaddr_in6 *)cur->ai_addr;
                  if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
                      IN6_IS_ADDR_MC_LINKLOCAL(&sin6->sin6_addr))
                        sin6->sin6_scope_id = scope;
            }
      }

      free(hostname2);

      return error;
#endif
}

static int
get_name(addr, afd, res, numaddr, pai, servname)
      const char *addr;
      const struct afd *afd;
      struct addrinfo **res;
      char *numaddr;
      const struct addrinfo *pai;
      const char *servname;
{
      struct hostent *hp = NULL;
      struct addrinfo *cur = NULL;
      int error = 0;
      char *ap = NULL, *cn = NULL;
#ifdef USE_GETIPNODEBY
      int h_error;

      hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
#else
      hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);
#endif
      if (hp && hp->h_name && hp->h_name[0] && hp->h_addr_list[0]) {
#ifdef USE_GETIPNODEBY
            GET_AI(cur, afd, hp->h_addr_list[0]);
            GET_PORT(cur, servname);
            GET_CANONNAME(cur, hp->h_name);
#else
            /* hp will be damaged if we use gethostbyaddr() */
            if ((ap = (char *)malloc(hp->h_length)) == NULL) {
                  error = EAI_MEMORY;
                  goto free;
            }
            memcpy(ap, hp->h_addr_list[0], hp->h_length);
            if ((cn = strdup(hp->h_name)) == NULL) {
                  error = EAI_MEMORY;
                  goto free;
            }

            GET_AI(cur, afd, ap);
            GET_PORT(cur, servname);
            GET_CANONNAME(cur, cn);
            free(ap); ap = NULL;
            free(cn); cn = NULL;
#endif
      } else {
            GET_AI(cur, afd, numaddr);
            GET_PORT(cur, servname);
      }
      
#ifdef USE_GETIPNODEBY
      if (hp)
            freehostent(hp);
#endif
      *res = cur;
      return SUCCESS;
 free:
      if (cur)
            freeaddrinfo(cur);
      if (ap)
            free(ap);
      if (cn)
            free(cn);
#ifdef USE_GETIPNODEBY
      if (hp)
            freehostent(hp);
#endif
      *res = NULL;
      return error;
}

static int
get_canonname(pai, ai, str)
      const struct addrinfo *pai;
      struct addrinfo *ai;
      const char *str;
{
      if ((pai->ai_flags & AI_CANONNAME) != 0) {
            ai->ai_canonname = (char *)malloc(strlen(str) + 1);
            if (ai->ai_canonname == NULL)
                  return EAI_MEMORY;
            strcpy(ai->ai_canonname, str);
      }
      return 0;
}

static struct addrinfo *
get_ai(pai, afd, addr)
      const struct addrinfo *pai;
      const struct afd *afd;
      const char *addr;
{
      char *p;
      struct addrinfo *ai;

      ai = (struct addrinfo *)malloc(sizeof(struct addrinfo)
            + (afd->a_socklen));
      if (ai == NULL)
            return NULL;

      memcpy(ai, pai, sizeof(struct addrinfo));
      ai->ai_addr = (struct sockaddr *)(ai + 1);
      memset(ai->ai_addr, 0, afd->a_socklen);
#ifdef HAVE_SOCKADDR_SA_LEN
      ai->ai_addr->sa_len = afd->a_socklen;
#endif
      ai->ai_addrlen = afd->a_socklen;
      ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
      p = (char *)(ai->ai_addr);
      memcpy(p + afd->a_off, addr, afd->a_addrlen);
      return ai;
}

static int
get_portmatch(ai, servname)
      const struct addrinfo *ai;
      const char *servname;
{

      /* get_port does not touch first argument. when matchonly == 1. */
      return get_port((struct addrinfo *)ai, servname, 1);
}

static int
get_port(ai, servname, matchonly)
      struct addrinfo *ai;
      const char *servname;
      int matchonly;
{
      const char *proto;
      struct servent *sp;
      int port;
      int allownumeric;

      if (servname == NULL)
            return 0;
      switch (ai->ai_family) {
      case AF_INET:
#ifdef AF_INET6
      case AF_INET6:
#endif
            break;
      default:
            return 0;
      }

      switch (ai->ai_socktype) {
      case SOCK_RAW:
            return EAI_SERVICE;
      case SOCK_DGRAM:
      case SOCK_STREAM:
            allownumeric = 1;
            break;
      case ANY:
            allownumeric = 0;
            break;
      default:
            return EAI_SOCKTYPE;
      }

      if (str_isnumber(servname)) {
            if (!allownumeric)
                  return EAI_SERVICE;
            port = htons(atoi(servname));
            if (port < 0 || port > 65535)
                  return EAI_SERVICE;
      } else {
            switch (ai->ai_socktype) {
            case SOCK_DGRAM:
                  proto = "udp";
                  break;
            case SOCK_STREAM:
                  proto = "tcp";
                  break;
            default:
                  proto = NULL;
                  break;
            }

            if ((sp = getservbyname(servname, proto)) == NULL)
                  return EAI_SERVICE;
            port = sp->s_port;
      }

      if (!matchonly) {
            switch (ai->ai_family) {
            case AF_INET:
                  ((struct sockaddr_in *)ai->ai_addr)->sin_port = port;
                  break;
#ifdef INET6
            case AF_INET6:
                  ((struct sockaddr_in6 *)ai->ai_addr)->sin6_port = port;
                  break;
#endif
            }
      }

      return 0;
}

static const struct afd *
find_afd(af)
      int af;
{
      const struct afd *afd;

      if (af == PF_UNSPEC)
            return NULL;
      for (afd = afdl; afd->a_af; afd++) {
            if (afd->a_af == af)
                  return afd;
      }
      return NULL;
}

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