/*
 * Issues to be discussed:
 * - Thread safe-ness must be checked
 */

#if ( defined(__linux__) || defined(__linux) || defined(LINUX) )
#ifndef IF_NAMESIZE
# ifdef IFNAMSIZ
#  define IF_NAMESIZE  IFNAMSIZ
# else
#  define IF_NAMESIZE 16
# endif
#endif
#endif

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by WIDE Project and
 *    its contributors.
 * 4. 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.
 */

#include <port_before.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <net/if.h>

#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stddef.h>

#include <port_after.h>

/*%
 * Note that a_off will be dynamically adjusted so that to be consistent
 * with the definition of sockaddr_in{,6}.
 * The value presented below is just a guess.
 */
static struct afd {
        int a_af;
        int a_addrlen;
        size_t a_socklen;
        int a_off;
} afdl [] = {
        /* first entry is linked last... */
        {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
         offsetof(struct sockaddr_in, sin_addr)},
        {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
         offsetof(struct sockaddr_in6, sin6_addr)},
        {0, 0, 0, 0},
};

struct sockinet {
#ifdef HAVE_SA_LEN
        u_char  si_len;
#endif
        u_char  si_family;
        u_short si_port;
};

static int ip6_parsenumeric __P((const struct sockaddr *, const char *, char *,
                                 size_t, int));
#ifdef HAVE_SIN6_SCOPE_ID
static int ip6_sa2str __P((const struct sockaddr_in6 *, char *, size_t, int));
#endif

int
getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
        const struct sockaddr *sa;
        size_t salen;
        char *host;
        size_t hostlen;
        char *serv;
        size_t servlen;
        int flags;
{
        struct afd *afd;
        struct servent *sp;
        struct hostent *hp;
        u_short port;
#ifdef HAVE_SA_LEN
        size_t len;
#endif
        int family, i;
        const char *addr;
        char *p;
        char numserv[512];
        char numaddr[512];
        const struct sockaddr_in6 *sin6;

        if (sa == NULL)
                return EAI_FAIL;

#ifdef HAVE_SA_LEN
        len = sa->sa_len;
        if (len != salen) return EAI_FAIL;
#endif

        family = sa->sa_family;
        for (i = 0; afdl[i].a_af; i++)
                if (afdl[i].a_af == family) {
                        afd = &afdl[i];
                        goto found;
                }
        return EAI_FAMILY;

 found:
        if (salen != afd->a_socklen) return EAI_FAIL;

        port = ((const struct sockinet *)sa)->si_port; /*%< network byte order */
        addr = (const char *)sa + afd->a_off;

        if (serv == NULL || servlen == 0U) {
                /*
                 * rfc2553bis says that serv == NULL or servlen == 0 means that
                 * the caller does not want the result.
                 */
        } else if (flags & NI_NUMERICSERV) {
                sprintf(numserv, "%d", ntohs(port));
                if (strlen(numserv) > servlen)
                        return EAI_MEMORY;
                strcpy(serv, numserv);
        } else {
                sp = getservbyport(port, (flags & NI_DGRAM) ? "udp" : "tcp");
                if (sp) {
                        if (strlen(sp->s_name) + 1 > servlen)
                                return EAI_MEMORY;
                        strcpy(serv, sp->s_name);
                } else
                        return EAI_NONAME;
        }

        switch (sa->sa_family) {
        case AF_INET:
                if (ntohl(*(const u_int32_t *)addr) >> IN_CLASSA_NSHIFT == 0)
                        flags |= NI_NUMERICHOST;
                break;
        case AF_INET6:
                sin6 = (const struct sockaddr_in6 *)sa;
                switch (sin6->sin6_addr.s6_addr[0]) {
                case 0x00:
                        if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
                                ;
                        else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
                                ;
                        else
                                flags |= NI_NUMERICHOST;
                        break;
                default:
                        if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr))
                                flags |= NI_NUMERICHOST;
                        else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
                                flags |= NI_NUMERICHOST;
                        break;
                }
                break;
        }
        if (host == NULL || hostlen == 0U) {
                /*
                 * rfc2553bis says that host == NULL or hostlen == 0 means that
                 * the caller does not want the result.
                 */
        } else if (flags & NI_NUMERICHOST) {
                goto numeric;
        } else {
                hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);

                if (hp) {
                        if (flags & NI_NOFQDN) {
                                p = strchr(hp->h_name, '.');
                                if (p) *p = '\0';
                        }
                        if (strlen(hp->h_name) + 1 > hostlen)
                                return EAI_MEMORY;
                        strcpy(host, hp->h_name);
                } else {
                        if (flags & NI_NAMEREQD)
                                return EAI_NONAME;
                  numeric:
                        switch(afd->a_af) {
                        case AF_INET6:
                        {
                                int error;

                                if ((error = ip6_parsenumeric(sa, addr, host,
                                                              hostlen,
                                                              flags)) != 0)
                                        return(error);
                                break;
                        }

                        default:
                                if (inet_ntop(afd->a_af, addr, numaddr,
                                              sizeof(numaddr)) == NULL)
                                        return EAI_NONAME;
                                if (strlen(numaddr) + 1 > hostlen)
                                        return EAI_MEMORY;
                                strcpy(host, numaddr);
                        }
                }
        }
        return(0);
}

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

#ifndef HAVE_SIN6_SCOPE_ID
        UNUSED(sa);
        UNUSED(flags);
#endif

        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_MEMORY;
        strcpy(host, numaddr);

#ifdef HAVE_SIN6_SCOPE_ID
        if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
                char scopebuf[MAXHOSTNAMELEN]; /*%< XXX */
                int scopelen;

                /* ip6_sa2str never fails */
                scopelen = ip6_sa2str((const struct sockaddr_in6 *)sa,
                                      scopebuf, sizeof(scopebuf), flags);

                if (scopelen + 1 + numaddrlen + 1 > hostlen)
                        return EAI_MEMORY;

                /* construct <numeric-addr><delim><scopeid> */
                memcpy(host + numaddrlen + 1, scopebuf,
                       scopelen);
                host[numaddrlen] = SCOPE_DELIMITER;
                host[numaddrlen + 1 + scopelen] = '\0';
        }
#endif

        return 0;
}

#ifdef HAVE_SIN6_SCOPE_ID
/* ARGSUSED */
static int
ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf,
           size_t bufsiz, int flags)
{
#ifdef USE_IFNAMELINKID
        unsigned int ifindex = (unsigned int)sa6->sin6_scope_id;
        const struct in6_addr *a6 = &sa6->sin6_addr;
#endif
        char tmp[64];

#ifdef NI_NUMERICSCOPE
        if (flags & NI_NUMERICSCOPE) {
                sprintf(tmp, "%u", sa6->sin6_scope_id);
                if (bufsiz != 0U) {
                        strncpy(buf, tmp, bufsiz - 1);
                        buf[bufsiz - 1] = '\0';
                }
                return(strlen(tmp));
        }
#endif

#ifdef USE_IFNAMELINKID
        /*
         * For a link-local address, convert the index to an interface
         * name, assuming a one-to-one mapping between links and interfaces.
         * Note, however, that this assumption is stronger than the
         * specification of the scoped address architecture;  the
         * specficication says that more than one interfaces can belong to
         * a single link.
         */

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

        /* last resort */
        sprintf(tmp, "%u", sa6->sin6_scope_id);
        if (bufsiz != 0U) {
                strncpy(buf, tmp, bufsiz - 1);
                buf[bufsiz - 1] = '\0';
        }
        return(strlen(tmp));
}
#endif

/*! \file */