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[netbsd-mini2440.git] / external / bsd / bind / dist / lib / lwres / getaddrinfo.c

/*      $NetBSD$        */

/*
 * Copyright (C) 2004-2008  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * This code is derived from software contributed to ISC by
 * Berkeley Software Design, Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC AND BERKELEY SOFTWARE DESIGN, INC.
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE
 * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* Id: getaddrinfo.c,v 1.54 2008/11/25 23:47:23 tbox Exp */

/*! \file */

/**
 *    lwres_getaddrinfo() is used to get a list of IP addresses and port
 *    numbers for host hostname and service servname. The function is the
 *    lightweight resolver's implementation of getaddrinfo() as defined in
 *    RFC2133. hostname and servname are pointers to null-terminated strings
 *    or NULL. hostname is either a host name or a numeric host address
 *    string: a dotted decimal IPv4 address or an IPv6 address. servname is
 *    either a decimal port number or a service name as listed in
 *    /etc/services.
 *
 *    If the operating system does not provide a struct addrinfo, the
 *    following structure is used:
 *
 * \code
 * struct  addrinfo {
 *         int             ai_flags;       // AI_PASSIVE, AI_CANONNAME
 *         int             ai_family;      // PF_xxx
 *         int             ai_socktype;    // SOCK_xxx
 *         int             ai_protocol;    // 0 or IPPROTO_xxx for IPv4 and IPv6
 *         size_t          ai_addrlen;     // length of ai_addr
 *         char            *ai_canonname;  // canonical name for hostname
 *         struct sockaddr *ai_addr;       // binary address
 *         struct addrinfo *ai_next;       // next structure in linked list
 * };
 * \endcode
 *
 *
 *    hints is an optional pointer to a struct addrinfo. This structure can
 *    be used to provide hints concerning the type of socket that the caller
 *    supports or wishes to use. The caller can supply the following
 *    structure elements in *hints:
 *
 * <ul>
 *    <li>ai_family:
 *           The protocol family that should be used. When ai_family is set
 *           to PF_UNSPEC, it means the caller will accept any protocol
 *           family supported by the operating system.</li>
 *
 *    <li>ai_socktype:
 *           denotes the type of socket -- SOCK_STREAM, SOCK_DGRAM or
 *           SOCK_RAW -- that is wanted. When ai_socktype is zero the caller
 *           will accept any socket type.</li>
 *
 *    <li>ai_protocol:
 *           indicates which transport protocol is wanted: IPPROTO_UDP or
 *           IPPROTO_TCP. If ai_protocol is zero the caller will accept any
 *           protocol.</li>
 *
 *    <li>ai_flags:
 *           Flag bits. If the AI_CANONNAME bit is set, a successful call to
 *           lwres_getaddrinfo() will return a null-terminated string
 *           containing the canonical name of the specified hostname in
 *           ai_canonname of the first addrinfo structure returned. Setting
 *           the AI_PASSIVE bit indicates that the returned socket address
 *           structure is intended for used in a call to bind(2). In this
 *           case, if the hostname argument is a NULL pointer, then the IP
 *           address portion of the socket address structure will be set to
 *           INADDR_ANY for an IPv4 address or IN6ADDR_ANY_INIT for an IPv6
 *           address.<br /><br />
 *
 *           When ai_flags does not set the AI_PASSIVE bit, the returned
 *           socket address structure will be ready for use in a call to
 *           connect(2) for a connection-oriented protocol or connect(2),
 *           sendto(2), or sendmsg(2) if a connectionless protocol was
 *           chosen. The IP address portion of the socket address structure
 *           will be set to the loopback address if hostname is a NULL
 *           pointer and AI_PASSIVE is not set in ai_flags.<br /><br />
 *
 *           If ai_flags is set to AI_NUMERICHOST it indicates that hostname
 *           should be treated as a numeric string defining an IPv4 or IPv6
 *           address and no name resolution should be attempted.
 * </li></ul>
 *
 *    All other elements of the struct addrinfo passed via hints must be
 *    zero.
 *
 *    A hints of NULL is treated as if the caller provided a struct addrinfo
 *    initialized to zero with ai_familyset to PF_UNSPEC.
 *
 *    After a successful call to lwres_getaddrinfo(), *res is a pointer to a
 *    linked list of one or more addrinfo structures. Each struct addrinfo
 *    in this list cn be processed by following the ai_next pointer, until a
 *    NULL pointer is encountered. The three members ai_family, ai_socktype,
 *    and ai_protocol in each returned addrinfo structure contain the
 *    corresponding arguments for a call to socket(2). For each addrinfo
 *    structure in the list, the ai_addr member points to a filled-in socket
 *    address structure of length ai_addrlen.
 *
 *    All of the information returned by lwres_getaddrinfo() is dynamically
 *    allocated: the addrinfo structures, and the socket address structures
 *    and canonical host name strings pointed to by the addrinfostructures.
 *    Memory allocated for the dynamically allocated structures created by a
 *    successful call to lwres_getaddrinfo() is released by
 *    lwres_freeaddrinfo(). ai is a pointer to a struct addrinfo created by
 *    a call to lwres_getaddrinfo().
 *
 * \section lwresreturn RETURN VALUES
 *
 *    lwres_getaddrinfo() returns zero on success or one of the error codes
 *    listed in gai_strerror() if an error occurs. If both hostname and
 *    servname are NULL lwres_getaddrinfo() returns #EAI_NONAME.
 *
 * \section lwressee SEE ALSO
 *
 *    lwres(3), lwres_getaddrinfo(), lwres_freeaddrinfo(),
 *    lwres_gai_strerror(), RFC2133, getservbyname(3), connect(2),
 *    sendto(2), sendmsg(2), socket(2).
 */

#include <config.h>

#include <errno.h>

#include <isc/string.h>

#include <lwres/lwres.h>
#include <lwres/net.h>
#include <lwres/netdb.h>
#include <lwres/stdlib.h>

#define SA(addr)        ((struct sockaddr *)(addr))
#define SIN(addr)       ((struct sockaddr_in *)(addr))
#define SIN6(addr)      ((struct sockaddr_in6 *)(addr))
#define SLOCAL(addr)    ((struct sockaddr_un *)(addr))

/*! \struct addrinfo
 */
static struct addrinfo
        *ai_reverse(struct addrinfo *oai),
        *ai_clone(struct addrinfo *oai, int family),
        *ai_alloc(int family, int addrlen);
#ifdef AF_LOCAL
static int get_local(const char *name, int socktype, struct addrinfo **res);
#endif

static int add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
    int socktype, int port);
static int add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
    int socktype, int port);
static void set_order(int, int (**)(const char *, int, struct addrinfo **,
         int, int));

#define FOUND_IPV4      0x1
#define FOUND_IPV6      0x2
#define FOUND_MAX       2

#define ISC_AI_MASK (AI_PASSIVE|AI_CANONNAME|AI_NUMERICHOST)
/*% Get a list of IP addresses and port numbers for host hostname and service servname. */
int
lwres_getaddrinfo(const char *hostname, const char *servname,
        const struct addrinfo *hints, struct addrinfo **res)
{
        struct servent *sp;
        const char *proto;
        int family, socktype, flags, protocol;
        struct addrinfo *ai, *ai_list;
        int port, err, i;
        int (*net_order[FOUND_MAX+1])(const char *, int, struct addrinfo **,
                 int, int);

        if (hostname == NULL && servname == NULL)
                return (EAI_NONAME);

        proto = NULL;
        if (hints != NULL) {
                if ((hints->ai_flags & ~(ISC_AI_MASK)) != 0)
                        return (EAI_BADFLAGS);
                if (hints->ai_addrlen || hints->ai_canonname ||
                    hints->ai_addr || hints->ai_next) {
                        errno = EINVAL;
                        return (EAI_SYSTEM);
                }
                family = hints->ai_family;
                socktype = hints->ai_socktype;
                protocol = hints->ai_protocol;
                flags = hints->ai_flags;
                switch (family) {
                case AF_UNSPEC:
                        switch (hints->ai_socktype) {
                        case SOCK_STREAM:
                                proto = "tcp";
                                break;
                        case SOCK_DGRAM:
                                proto = "udp";
                                break;
                        }
                        break;
                case AF_INET:
                case AF_INET6:
                        switch (hints->ai_socktype) {
                        case 0:
                                break;
                        case SOCK_STREAM:
                                proto = "tcp";
                                break;
                        case SOCK_DGRAM:
                                proto = "udp";
                                break;
                        case SOCK_RAW:
                                break;
                        default:
                                return (EAI_SOCKTYPE);
                        }
                        break;
#ifdef  AF_LOCAL
                case AF_LOCAL:
                        switch (hints->ai_socktype) {
                        case 0:
                                break;
                        case SOCK_STREAM:
                                break;
                        case SOCK_DGRAM:
                                break;
                        default:
                                return (EAI_SOCKTYPE);
                        }
                        break;
#endif
                default:
                        return (EAI_FAMILY);
                }
        } else {
                protocol = 0;
                family = 0;
                socktype = 0;
                flags = 0;
        }

#ifdef  AF_LOCAL
        /*!
         * First, deal with AF_LOCAL.  If the family was not set,
         * then assume AF_LOCAL if the first character of the
         * hostname/servname is '/'.
         */

        if (hostname != NULL &&
            (family == AF_LOCAL || (family == 0 && *hostname == '/')))
                return (get_local(hostname, socktype, res));

        if (servname != NULL &&
            (family == AF_LOCAL || (family == 0 && *servname == '/')))
                return (get_local(servname, socktype, res));
#endif

        /*
         * Ok, only AF_INET and AF_INET6 left.
         */
        ai_list = NULL;

        /*
         * First, look up the service name (port) if it was
         * requested.  If the socket type wasn't specified, then
         * try and figure it out.
         */
        if (servname != NULL) {
                char *e;

                port = strtol(servname, &e, 10);
                if (*e == '\0') {
                        if (socktype == 0)
                                return (EAI_SOCKTYPE);
                        if (port < 0 || port > 65535)
                                return (EAI_SERVICE);
                        port = htons((unsigned short) port);
                } else {
                        sp = getservbyname(servname, proto);
                        if (sp == NULL)
                                return (EAI_SERVICE);
                        port = sp->s_port;
                        if (socktype == 0) {
                                if (strcmp(sp->s_proto, "tcp") == 0)
                                        socktype = SOCK_STREAM;
                                else if (strcmp(sp->s_proto, "udp") == 0)
                                        socktype = SOCK_DGRAM;
                        }
                }
        } else
                port = 0;

        /*
         * Next, deal with just a service name, and no hostname.
         * (we verified that one of them was non-null up above).
         */
        if (hostname == NULL && (flags & AI_PASSIVE) != 0) {
                if (family == AF_INET || family == 0) {
                        ai = ai_alloc(AF_INET, sizeof(struct sockaddr_in));
                        if (ai == NULL)
                                return (EAI_MEMORY);
                        ai->ai_socktype = socktype;
                        ai->ai_protocol = protocol;
                        SIN(ai->ai_addr)->sin_port = port;
                        ai->ai_next = ai_list;
                        ai_list = ai;
                }

                if (family == AF_INET6 || family == 0) {
                        ai = ai_alloc(AF_INET6, sizeof(struct sockaddr_in6));
                        if (ai == NULL) {
                                lwres_freeaddrinfo(ai_list);
                                return (EAI_MEMORY);
                        }
                        ai->ai_socktype = socktype;
                        ai->ai_protocol = protocol;
                        SIN6(ai->ai_addr)->sin6_port = port;
                        ai->ai_next = ai_list;
                        ai_list = ai;
                }

                *res = ai_list;
                return (0);
        }

        /*
         * If the family isn't specified or AI_NUMERICHOST specified,
         * check first to see if it is a numeric address.
         * Though the gethostbyname2() routine
         * will recognize numeric addresses, it will only recognize
         * the format that it is being called for.  Thus, a numeric
         * AF_INET address will be treated by the AF_INET6 call as
         * a domain name, and vice versa.  Checking for both numerics
         * here avoids that.
         */
        if (hostname != NULL &&
            (family == 0 || (flags & AI_NUMERICHOST) != 0)) {
                char abuf[sizeof(struct in6_addr)];
                char nbuf[NI_MAXHOST];
                int addrsize, addroff;
#ifdef LWRES_HAVE_SIN6_SCOPE_ID
                char *p, *ep;
                char ntmp[NI_MAXHOST];
                lwres_uint32_t scopeid;
#endif

#ifdef LWRES_HAVE_SIN6_SCOPE_ID
                /*
                 * Scope identifier portion.
                 */
                ntmp[0] = '\0';
                if (strchr(hostname, '%') != NULL) {
                        strncpy(ntmp, hostname, sizeof(ntmp) - 1);
                        ntmp[sizeof(ntmp) - 1] = '\0';
                        p = strchr(ntmp, '%');
                        ep = NULL;

                        /*
                         * Vendors may want to support non-numeric
                         * scopeid around here.
                         */

                        if (p != NULL)
                                scopeid = (lwres_uint32_t)strtoul(p + 1,
                                                                  &ep, 10);
                        if (p != NULL && ep != NULL && ep[0] == '\0')
                                *p = '\0';
                        else {
                                ntmp[0] = '\0';
                                scopeid = 0;
                        }
                } else
                        scopeid = 0;
#endif

               if (lwres_net_pton(AF_INET, hostname, (struct in_addr *)abuf)
                   == 1)
               {
                        if (family == AF_INET6) {
                                /*
                                 * Convert to a V4 mapped address.
                                 */
                                struct in6_addr *a6 = (struct in6_addr *)abuf;
                                memcpy(&a6->s6_addr[12], &a6->s6_addr[0], 4);
                                memset(&a6->s6_addr[10], 0xff, 2);
                                memset(&a6->s6_addr[0], 0, 10);
                                goto inet6_addr;
                        }
                        addrsize = sizeof(struct in_addr);
                        addroff = (char *)(&SIN(0)->sin_addr) - (char *)0;
                        family = AF_INET;
                        goto common;
#ifdef LWRES_HAVE_SIN6_SCOPE_ID
                } else if (ntmp[0] != '\0' &&
                           lwres_net_pton(AF_INET6, ntmp, abuf) == 1)
                {
                        if (family && family != AF_INET6)
                                return (EAI_NONAME);
                        addrsize = sizeof(struct in6_addr);
                        addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
                        family = AF_INET6;
                        goto common;
#endif
                } else if (lwres_net_pton(AF_INET6, hostname, abuf) == 1) {
                        if (family != 0 && family != AF_INET6)
                                return (EAI_NONAME);
                inet6_addr:
                        addrsize = sizeof(struct in6_addr);
                        addroff = (char *)(&SIN6(0)->sin6_addr) - (char *)0;
                        family = AF_INET6;

                common:
                        ai = ai_clone(ai_list, family);
                        if (ai == NULL)
                                return (EAI_MEMORY);
                        ai_list = ai;
                        ai->ai_socktype = socktype;
                        SIN(ai->ai_addr)->sin_port = port;
                        memcpy((char *)ai->ai_addr + addroff, abuf, addrsize);
                        if (flags & AI_CANONNAME) {
#if defined(LWRES_HAVE_SIN6_SCOPE_ID)
                                if (ai->ai_family == AF_INET6)
                                        SIN6(ai->ai_addr)->sin6_scope_id =
                                                                        scopeid;
#endif
                                if (lwres_getnameinfo(ai->ai_addr,
                                    ai->ai_addrlen, nbuf, sizeof(nbuf),
                                                      NULL, 0,
                                                      NI_NUMERICHOST) == 0) {
                                        ai->ai_canonname = strdup(nbuf);
                                        if (ai->ai_canonname == NULL) {
                                                lwres_freeaddrinfo(ai_list);
                                                return (EAI_MEMORY);
                                        }
                                } else {
                                        /* XXX raise error? */
                                        ai->ai_canonname = NULL;
                                }
                        }
                        goto done;
                } else if ((flags & AI_NUMERICHOST) != 0) {
                        return (EAI_NONAME);
                }
        }

        set_order(family, net_order);
        for (i = 0; i < FOUND_MAX; i++) {
                if (net_order[i] == NULL)
                        break;
                err = (net_order[i])(hostname, flags, &ai_list,
                                     socktype, port);
                if (err != 0)
                        return (err);
        }

        if (ai_list == NULL)
                return (EAI_NODATA);

done:
        ai_list = ai_reverse(ai_list);

        *res = ai_list;
        return (0);
}

static char *
lwres_strsep(char **stringp, const char *delim) {
        char *string = *stringp;
        char *s;
        const char *d;
        char sc, dc;

        if (string == NULL)
                return (NULL);

        for (s = string; *s != '\0'; s++) {
                sc = *s;
                for (d = delim; (dc = *d) != '\0'; d++)
                        if (sc == dc) {
                                *s++ = '\0';
                                *stringp = s;
                                return (string);
                        }
        }
        *stringp = NULL;
        return (string);
}

static void
set_order(int family, int (**net_order)(const char *, int, struct addrinfo **,
                                        int, int))
{
        char *order, *tok;
        int found;

        if (family) {
                switch (family) {
                case AF_INET:
                        *net_order++ = add_ipv4;
                        break;
                case AF_INET6:
                        *net_order++ = add_ipv6;
                        break;
                }
        } else {
                order = getenv("NET_ORDER");
                found = 0;
                while (order != NULL) {
                        /*
                         * We ignore any unknown names.
                         */
                        tok = lwres_strsep(&order, ":");
                        if (strcasecmp(tok, "inet6") == 0) {
                                if ((found & FOUND_IPV6) == 0)
                                        *net_order++ = add_ipv6;
                                found |= FOUND_IPV6;
                        } else if (strcasecmp(tok, "inet") == 0 ||
                            strcasecmp(tok, "inet4") == 0) {
                                if ((found & FOUND_IPV4) == 0)
                                        *net_order++ = add_ipv4;
                                found |= FOUND_IPV4;
                        }
                }

                /*
                 * Add in anything that we didn't find.
                 */
                if ((found & FOUND_IPV4) == 0)
                        *net_order++ = add_ipv4;
                if ((found & FOUND_IPV6) == 0)
                        *net_order++ = add_ipv6;
        }
        *net_order = NULL;
        return;
}

static char v4_loop[4] = { 127, 0, 0, 1 };

/*
 * The test against 0 is there to keep the Solaris compiler
 * from complaining about "end-of-loop code not reached".
 */
#define SETERROR(code) \
        do { result = (code);                   \
                if (result != 0) goto cleanup;  \
        } while (0)

static int
add_ipv4(const char *hostname, int flags, struct addrinfo **aip,
        int socktype, int port)
{
        struct addrinfo *ai;
        lwres_context_t *lwrctx = NULL;
        lwres_gabnresponse_t *by = NULL;
        lwres_addr_t *addr;
        lwres_result_t lwres;
        int result = 0;

        lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
        if (lwres != LWRES_R_SUCCESS)
                SETERROR(EAI_FAIL);
        (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
        if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
                ai = ai_clone(*aip, AF_INET);
                if (ai == NULL) {
                        lwres_freeaddrinfo(*aip);
                        SETERROR(EAI_MEMORY);
                }

                *aip = ai;
                ai->ai_socktype = socktype;
                SIN(ai->ai_addr)->sin_port = port;
                memcpy(&SIN(ai->ai_addr)->sin_addr, v4_loop, 4);
        } else {
                lwres = lwres_getaddrsbyname(lwrctx, hostname,
                                             LWRES_ADDRTYPE_V4, &by);
                if (lwres != LWRES_R_SUCCESS) {
                        if (lwres == LWRES_R_NOTFOUND)
                                goto cleanup;
                        else
                                SETERROR(EAI_FAIL);
                }
                addr = LWRES_LIST_HEAD(by->addrs);
                while (addr != NULL) {
                        ai = ai_clone(*aip, AF_INET);
                        if (ai == NULL) {
                                lwres_freeaddrinfo(*aip);
                                SETERROR(EAI_MEMORY);
                        }
                        *aip = ai;
                        ai->ai_socktype = socktype;
                        SIN(ai->ai_addr)->sin_port = port;
                        memcpy(&SIN(ai->ai_addr)->sin_addr,
                               addr->address, 4);
                        if (flags & AI_CANONNAME) {
                                ai->ai_canonname = strdup(by->realname);
                                if (ai->ai_canonname == NULL)
                                        SETERROR(EAI_MEMORY);
                        }
                        addr = LWRES_LIST_NEXT(addr, link);
                }
        }
 cleanup:
        if (by != NULL)
                lwres_gabnresponse_free(lwrctx, &by);
        if (lwrctx != NULL) {
                lwres_conf_clear(lwrctx);
                lwres_context_destroy(&lwrctx);
        }
        return (result);
}

static char v6_loop[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 };

static int
add_ipv6(const char *hostname, int flags, struct addrinfo **aip,
         int socktype, int port)
{
        struct addrinfo *ai;
        lwres_context_t *lwrctx = NULL;
        lwres_gabnresponse_t *by = NULL;
        lwres_addr_t *addr;
        lwres_result_t lwres;
        int result = 0;

        lwres = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
        if (lwres != LWRES_R_SUCCESS)
                SETERROR(EAI_FAIL);
        (void) lwres_conf_parse(lwrctx, lwres_resolv_conf);

        if (hostname == NULL && (flags & AI_PASSIVE) == 0) {
                ai = ai_clone(*aip, AF_INET6);
                if (ai == NULL) {
                        lwres_freeaddrinfo(*aip);
                        SETERROR(EAI_MEMORY);
                }

                *aip = ai;
                ai->ai_socktype = socktype;
                SIN6(ai->ai_addr)->sin6_port = port;
                memcpy(&SIN6(ai->ai_addr)->sin6_addr, v6_loop, 16);
        } else {
                lwres = lwres_getaddrsbyname(lwrctx, hostname,
                                             LWRES_ADDRTYPE_V6, &by);
                if (lwres != LWRES_R_SUCCESS) {
                        if (lwres == LWRES_R_NOTFOUND)
                                goto cleanup;
                        else
                                SETERROR(EAI_FAIL);
                }
                addr = LWRES_LIST_HEAD(by->addrs);
                while (addr != NULL) {
                        ai = ai_clone(*aip, AF_INET6);
                        if (ai == NULL) {
                                lwres_freeaddrinfo(*aip);
                                SETERROR(EAI_MEMORY);
                        }
                        *aip = ai;
                        ai->ai_socktype = socktype;
                        SIN6(ai->ai_addr)->sin6_port = port;
                        memcpy(&SIN6(ai->ai_addr)->sin6_addr,
                               addr->address, 16);
                        if (flags & AI_CANONNAME) {
                                ai->ai_canonname = strdup(by->realname);
                                if (ai->ai_canonname == NULL)
                                        SETERROR(EAI_MEMORY);
                        }
                        addr = LWRES_LIST_NEXT(addr, link);
                }
        }
 cleanup:
        if (by != NULL)
                lwres_gabnresponse_free(lwrctx, &by);
        if (lwrctx != NULL) {
                lwres_conf_clear(lwrctx);
                lwres_context_destroy(&lwrctx);
        }
        return (result);
}

/*% Free address info. */
void
lwres_freeaddrinfo(struct addrinfo *ai) {
        struct addrinfo *ai_next;

        while (ai != NULL) {
                ai_next = ai->ai_next;
                if (ai->ai_addr != NULL)
                        free(ai->ai_addr);
                if (ai->ai_canonname)
                        free(ai->ai_canonname);
                free(ai);
                ai = ai_next;
        }
}

#ifdef AF_LOCAL
static int
get_local(const char *name, int socktype, struct addrinfo **res) {
        struct addrinfo *ai;
        struct sockaddr_un *slocal;

        if (socktype == 0)
                return (EAI_SOCKTYPE);

        ai = ai_alloc(AF_LOCAL, sizeof(*slocal));
        if (ai == NULL)
                return (EAI_MEMORY);

        slocal = SLOCAL(ai->ai_addr);
        strncpy(slocal->sun_path, name, sizeof(slocal->sun_path));

        ai->ai_socktype = socktype;
        /*
         * ai->ai_flags, ai->ai_protocol, ai->ai_canonname,
         * and ai->ai_next were initialized to zero.
         */

        *res = ai;
        return (0);
}
#endif

/*!
 * Allocate an addrinfo structure, and a sockaddr structure
 * of the specificed length.  We initialize:
 *      ai_addrlen
 *      ai_family
 *      ai_addr
 *      ai_addr->sa_family
 *      ai_addr->sa_len (LWRES_PLATFORM_HAVESALEN)
 * and everything else is initialized to zero.
 */
static struct addrinfo *
ai_alloc(int family, int addrlen) {
        struct addrinfo *ai;

        ai = (struct addrinfo *)calloc(1, sizeof(*ai));
        if (ai == NULL)
                return (NULL);

        ai->ai_addr = SA(calloc(1, addrlen));
        if (ai->ai_addr == NULL) {
                free(ai);
                return (NULL);
        }
        ai->ai_addrlen = addrlen;
        ai->ai_family = family;
        ai->ai_addr->sa_family = family;
#ifdef LWRES_PLATFORM_HAVESALEN
        ai->ai_addr->sa_len = addrlen;
#endif
        return (ai);
}

static struct addrinfo *
ai_clone(struct addrinfo *oai, int family) {
        struct addrinfo *ai;

        ai = ai_alloc(family, ((family == AF_INET6) ?
            sizeof(struct sockaddr_in6) : sizeof(struct sockaddr_in)));

        if (ai == NULL) {
                lwres_freeaddrinfo(oai);
                return (NULL);
        }
        if (oai == NULL)
                return (ai);

        ai->ai_flags = oai->ai_flags;
        ai->ai_socktype = oai->ai_socktype;
        ai->ai_protocol = oai->ai_protocol;
        ai->ai_canonname = NULL;
        ai->ai_next = oai;
        return (ai);
}

static struct addrinfo *
ai_reverse(struct addrinfo *oai) {
        struct addrinfo *nai, *tai;

        nai = NULL;

        while (oai != NULL) {
                /*
                 * Grab one off the old list.
                 */
                tai = oai;
                oai = oai->ai_next;
                /*
                 * Put it on the front of the new list.
                 */
                tai->ai_next = nai;
                nai = tai;
        }
        return (nai);
}