/*      $KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $    */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * Copyright (c) 2000 Ben Harris.
 * 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.
 */

/*
 * Issues to be discussed:
 * - Thread safe-ness must be checked
 * - RFC2553 says that we should raise error on short buffer.  X/Open says
 *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
 *   modified).  ipngwg rough consensus seems to follow RFC2553.
 * - What is "local" in NI_FQDN?
 * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
 * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
 *   sin6_scope_id is filled - standardization status?
 *   XXX breaks backward compat for code that expects no scopeid.
 *   beware on merge.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/firewire.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stddef.h>
#include <errno.h>

static const struct afd *find_afd(int);
static int getnameinfo_inet(const struct afd *,
    const struct sockaddr *, socklen_t, char *,
    size_t, char *, size_t, int);
#ifdef INET6
static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
    size_t, int);
static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
#endif
static int getnameinfo_link(const struct afd *,
    const struct sockaddr *, socklen_t, char *,
    size_t, char *, size_t, int);
static int hexname(const u_int8_t *, size_t, char *, size_t);
static int getnameinfo_un(const struct afd *,
    const struct sockaddr *, socklen_t, char *,
    size_t, char *, size_t, int);

static const struct afd {
        int a_af;
        size_t a_addrlen;
        socklen_t a_socklen;
        int a_off;
        int (*a_func)(const struct afd *,
            const struct sockaddr *, socklen_t, char *,
            size_t, char *, size_t, int);
} afdl [] = {
#ifdef INET6
        {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
            offsetof(struct sockaddr_in6, sin6_addr),
            getnameinfo_inet},
#endif
        {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
            offsetof(struct sockaddr_in, sin_addr),
            getnameinfo_inet},
#define sizeofmember(type, member)      (sizeof(((type *)0)->member))
        {PF_LOCAL, sizeofmember(struct sockaddr_un, sun_path),
            sizeof(struct sockaddr_un),
            offsetof(struct sockaddr_un, sun_path),
            getnameinfo_un},
        {PF_LINK, sizeofmember(struct sockaddr_dl, sdl_data),
            sizeof(struct sockaddr_dl),
            offsetof(struct sockaddr_dl, sdl_data),
            getnameinfo_link},
        {0, 0, 0},
};

int
getnameinfo(const struct sockaddr *sa, socklen_t salen,
    char *host, size_t hostlen, char *serv, size_t servlen,
    int flags)
{
        const struct afd *afd;

        if (sa == NULL)
                return (EAI_FAIL);

        afd = find_afd(sa->sa_family);
        if (afd == NULL)
                return (EAI_FAMILY);
        /*
         * getnameinfo() accepts an salen of sizeof(struct sockaddr_storage)
         * at maximum as shown in RFC 4038 Sec.6.2.3.
         */
        if (salen > sizeof(struct sockaddr_storage))
                return (EAI_FAMILY);

        switch (sa->sa_family) {
        case PF_LOCAL:
                /*
                 * PF_LOCAL uses variable salen depending on the
                 * content length of sun_path.  Require 1 byte in
                 * sun_path at least.
                 */
                if (salen <= afd->a_socklen -
                        sizeofmember(struct sockaddr_un, sun_path))
                        return (EAI_FAMILY);
                else if (salen > afd->a_socklen)
                        salen = afd->a_socklen;
                break;
        case PF_LINK:
                if (salen <= afd->a_socklen -
                        sizeofmember(struct sockaddr_dl, sdl_data))
                        return (EAI_FAMILY);
                break;
        default:
                if (salen < afd->a_socklen)
                        return (EAI_FAMILY);
                else
                        salen = afd->a_socklen;
                break;
        }

        return ((*afd->a_func)(afd, sa, salen, host, hostlen,
            serv, servlen, flags));
}

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

        if (af == PF_UNSPEC)
                return (NULL);
        for (afd = &afdl[0]; afd->a_af > 0; afd++) {
                if (afd->a_af == af)
                        return (afd);
        }
        return (NULL);
}

static int
getnameinfo_inet(const struct afd *afd,
    const struct sockaddr *sa, socklen_t salen,
    char *host, size_t hostlen, char *serv, size_t servlen,
    int flags)
{
        struct servent *sp;
        struct hostent *hp;
        u_short port;
        const char *addr;
        u_int32_t v4a;
        int h_error;
        char numserv[512];
        char numaddr[512];

        /* network byte order */
        port = ((const struct sockaddr_in *)sa)->sin_port;
        addr = (const char *)sa + afd->a_off;

        if (serv == NULL || servlen == 0) {
                /*
                 * do nothing in this case.
                 * in case you are wondering if "&&" is more correct than
                 * "||" here: rfc2553bis-03 says that serv == NULL OR
                 * servlen == 0 means that the caller does not want the result.
                 */
        } else {
                if (flags & NI_NUMERICSERV)
                        sp = NULL;
                else {
                        sp = getservbyport(port,
                                (flags & NI_DGRAM) ? "udp" : "tcp");
                }
                if (sp) {
                        if (strlen(sp->s_name) + 1 > servlen)
                                return EAI_MEMORY;
                        strlcpy(serv, sp->s_name, servlen);
                } else {
                        snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
                        if (strlen(numserv) + 1 > servlen)
                                return EAI_MEMORY;
                        strlcpy(serv, numserv, servlen);
                }
        }

        switch (sa->sa_family) {
        case AF_INET:
                v4a = (u_int32_t)
                    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
                if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a) ||
                    IN_ZERONET(v4a))
                        flags |= NI_NUMERICHOST;
                break;
#ifdef INET6
        case AF_INET6:
            {
                const struct sockaddr_in6 *sin6;

                sin6 = (const struct sockaddr_in6 *)sa;

                /*
                 * https://pubs.opengroup.org/onlinepubs/9699919799/functions/getnameinfo.html
                 * "[IP6] [Option Start] If the socket address structure
                 * contains an IPv4-mapped IPv6 address or an IPv4-compatible
                 * IPv6 address, the implementation shall extract the embedded
                 * IPv4 address and lookup the node name for that IPv4 address.
                 * [Option End]"
                 * => getipnodebyaddr() handles this case for us.
                 * => in case of NI_NUMERICHOST being set, inet_ntop[6] will
                 *    handle it too.
                 *
                 * "If the address is the IPv6 unspecified address ( "::" ),
                 * a lookup shall not be performed and the behavior shall be
                 * the same as when the node's name cannot be located."
                 * => getipnodebyaddr() handles this case for us.
                 * => in case of NI_NUMERICHOST being set,
                 *    ip6_parsenumeric() -> inet_ntop[6] will handle it too.
                 */

                /*
                 * We used to exclude link-local from lookups.
                 * Even though calles in the resolver chain may not (yet)
                 * properly deal with them, we no longer do as for link-local
                 * there is a path to resolve these. See:
                 * RFC 6303 4.5.  IPv6 Link-Local Addresses
                 * RFC 6762 4.  Reverse Address Mapping
                 *
                 * XXX For IPv6 MC the only reference found was
                 * https://www.ietf.org/archive/id/draft-michaelson-as112-ipv6-02.html
                 * but there are also no "empty zone"s for x.0.f.f.ip6.arpa
                 * in DNS servers.  Keep catching it here for now and
                 * do not attempt name resolution but return the address string.
                 */
                if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
                        flags |= NI_NUMERICHOST;
            }
                break;
#endif
        }
        if (host == NULL || hostlen == 0) {
                /*
                 * do nothing in this case.
                 * in case you are wondering if "&&" is more correct than
                 * "||" here: rfc2553bis-03 says that host == NULL or
                 * hostlen == 0 means that the caller does not want the result.
                 */
        } else if (flags & NI_NUMERICHOST) {
                size_t numaddrlen;

                /* NUMERICHOST and NAMEREQD conflicts with each other */
                if (flags & NI_NAMEREQD)
                        return EAI_NONAME;

                switch(afd->a_af) {
#ifdef INET6
                case AF_INET6:
                {
                        int error;

                        if ((error = ip6_parsenumeric(sa, addr, host,
                                                      hostlen, flags)) != 0)
                                return(error);
                        break;
                }
#endif
                default:
                        if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
                            == NULL)
                                return EAI_SYSTEM;
                        numaddrlen = strlen(numaddr);
                        if (numaddrlen + 1 > hostlen) /* don't forget terminator */
                                return EAI_MEMORY;
                        strlcpy(host, numaddr, hostlen);
                        break;
                }
        } else {
                hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);

                if (hp) {
#if 0
                        /*
                         * commented out, since "for local host" is not
                         * implemented here - see RFC2553 p30
                         */
                        if (flags & NI_NOFQDN) {
                                char *p;
                                p = strchr(hp->h_name, '.');
                                if (p)
                                        *p = '\0';
                        }
#endif
                        if (strlen(hp->h_name) + 1 > hostlen) {
                                freehostent(hp);
                                return EAI_MEMORY;
                        }
                        strlcpy(host, hp->h_name, hostlen);
                        freehostent(hp);
                } else {
                        if (flags & NI_NAMEREQD)
                                return EAI_NONAME;
                        switch(afd->a_af) {
#ifdef INET6
                        case AF_INET6:
                        {
                                int error;

                                if ((error = ip6_parsenumeric(sa, addr, host,
                                                              hostlen,
                                                              flags)) != 0)
                                        return(error);
                                break;
                        }
#endif
                        default:
                                if (inet_ntop(afd->a_af, addr, host,
                                    hostlen) == NULL)
                                        return EAI_SYSTEM;
                                break;
                        }
                }
        }
        return(0);
}

#ifdef INET6
static int
ip6_parsenumeric(const struct sockaddr *sa, const char *addr,
    char *host, size_t hostlen, int flags)
{
        size_t numaddrlen;
        char numaddr[512];

        if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
                return EAI_SYSTEM;

        numaddrlen = strlen(numaddr);
        if (numaddrlen + 1 > hostlen) /* don't forget terminator */
                return EAI_OVERFLOW;
        strlcpy(host, numaddr, hostlen);

        if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
                char zonebuf[MAXHOSTNAMELEN];
                int zonelen;

                zonelen = ip6_sa2str(
                    (const struct sockaddr_in6 *)(const void *)sa,
                    zonebuf, sizeof(zonebuf), flags);
                if (zonelen < 0)
                        return EAI_OVERFLOW;
                if (zonelen + 1 + numaddrlen + 1 > hostlen)
                        return EAI_OVERFLOW;

                /* construct <numeric-addr><delim><zoneid> */
                memcpy(host + numaddrlen + 1, zonebuf,
                    (size_t)zonelen);
                host[numaddrlen] = SCOPE_DELIMITER;
                host[numaddrlen + 1 + zonelen] = '\0';
        }

        return 0;
}

/* ARGSUSED */
static int
ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
{
        unsigned int ifindex;
        const struct in6_addr *a6;
        int n;

        ifindex = (unsigned int)sa6->sin6_scope_id;
        a6 = &sa6->sin6_addr;

        if ((flags & NI_NUMERICSCOPE) != 0) {
                n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
                if (n < 0 || n >= bufsiz)
                        return -1;
                else
                        return n;
        }

        /* if_indextoname() does not take buffer size.  not a good api... */
        if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
             IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
                char *p = if_indextoname(ifindex, buf);
                if (p) {
                        return(strlen(p));
                }
        }

        /* last resort */
        n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
        if (n < 0 || (size_t)n >= bufsiz)
                return -1;
        else
                return n;
}
#endif /* INET6 */

/*
 * getnameinfo_link():
 * Format a link-layer address into a printable format, paying attention to
 * the interface type.
 */
/* ARGSUSED */
static int
getnameinfo_link(const struct afd *afd,
    const struct sockaddr *sa, socklen_t salen,
    char *host, size_t hostlen, char *serv, size_t servlen, int flags)
{
        const struct sockaddr_dl *sdl =
            (const struct sockaddr_dl *)(const void *)sa;
        const struct fw_hwaddr *iha;
        int n;

        if (serv != NULL && servlen > 0)
                *serv = '\0';

        if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
                n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
                if (n >= hostlen) {
                        *host = '\0';
                        return (EAI_MEMORY);
                }
                return (0);
        }

        if (sdl->sdl_nlen > 0 && sdl->sdl_alen == 0) {
                n = sdl->sdl_nlen;
                if (n >= hostlen) {
                        *host = '\0';
                        return (EAI_MEMORY);
                }
                memcpy(host, sdl->sdl_data, sdl->sdl_nlen);
                host[n] = '\0';
                return (0);
        }

        switch (sdl->sdl_type) {
        case IFT_IEEE1394:
                if (sdl->sdl_alen < sizeof(iha->sender_unique_ID_hi) +
                    sizeof(iha->sender_unique_ID_lo))
                        return EAI_FAMILY;
                iha = (const struct fw_hwaddr *)(const void *)LLADDR(sdl);
                return hexname((const u_int8_t *)&iha->sender_unique_ID_hi,
                    sizeof(iha->sender_unique_ID_hi) +
                    sizeof(iha->sender_unique_ID_lo),
                    host, hostlen);
        /*
         * The following have zero-length addresses.
         * IFT_GIF      (net/if_gif.c)
         * IFT_LOOP     (net/if_loop.c)
         * IFT_PPP      (net/if_tuntap.c)
         * IFT_SLIP     (net/if_sl.c, net/if_strip.c)
         * IFT_STF      (net/if_stf.c)
         * IFT_L2VLAN   (net/if_vlan.c)
         * IFT_BRIDGE (net/if_bridge.h>
         */
        /*
         * The following use IPv4 addresses as link-layer addresses:
         * IFT_OTHER    (net/if_gre.c)
         * IFT_OTHER    (netinet/ip_ipip.c)
         */
        /* default below is believed correct for all these. */
        case IFT_ETHER:
        case IFT_FDDI:
        case IFT_HIPPI:
        case IFT_ISO88025:
        default:
                return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
                    host, hostlen);
        }
}

static int
hexname(const u_int8_t *cp, size_t len, char *host, size_t hostlen)
{
        int i, n;
        char *outp = host;

        *outp = '\0';
        for (i = 0; i < len; i++) {
                n = snprintf(outp, hostlen, "%s%02x",
                    i ? ":" : "", cp[i]);
                if (n < 0 || n >= hostlen) {
                        *host = '\0';
                        return EAI_MEMORY;
                }
                outp += n;
                hostlen -= n;
        }
        return 0;
}

/*
 * getnameinfo_un():
 * Format a UNIX IPC domain address (pathname).
 */
/* ARGSUSED */
static int
getnameinfo_un(const struct afd *afd,
    const struct sockaddr *sa, socklen_t salen,
    char *host, size_t hostlen, char *serv, size_t servlen, int flags)
{
        size_t pathlen;

        if (serv != NULL && servlen > 0)
                *serv = '\0';
        if (host != NULL && hostlen > 0) {
                pathlen = salen - afd->a_off;

                if (pathlen + 1 > hostlen) {
                        *host = '\0';
                        return (EAI_MEMORY);
                }
                strlcpy(host, (const char *)sa + afd->a_off, pathlen + 1);
        }

        return (0);
}