/*
 * Copyright (c) 1985, 1988, 1993
 *    The Regents of the University of California.  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 the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 */

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and 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 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.
 */

/* from gethostnamadr.c 8.1 (Berkeley) 6/4/93 */
/* BIND Id: gethnamaddr.c,v 8.15 1996/05/22 04:56:30 vixie Exp $ */

/* Imports. */

#include "port_before.h"

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

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

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <irs.h>
#include <isc/memcluster.h>

#include "port_after.h"

#include "irs_p.h"
#include "dns_p.h"
#include "lcl_p.h"

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) sprintf x
#endif

/* Definitions. */

#define MAXALIASES      35
#define MAXADDRS        35
#define Max(a,b)        ((a) > (b) ? (a) : (b))

#if PACKETSZ > 1024
#define MAXPACKET       PACKETSZ
#else
#define MAXPACKET       1024
#endif

struct pvt {
        FILE *          fp;
        struct hostent  host;
        char *          h_addr_ptrs[MAXADDRS + 1];
        char *          host_aliases[MAXALIASES];
        char            hostbuf[8*1024];
        u_char          host_addr[16];  /*%< IPv4 or IPv6 */
        struct __res_state  *res;
        void            (*free_res)(void *);
};

typedef union {
        int32_t al;
        char ac;
} align;

static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };

/* Forward. */

static void             ho_close(struct irs_ho *this);
static struct hostent * ho_byname(struct irs_ho *this, const char *name);
static struct hostent * ho_byname2(struct irs_ho *this, const char *name,
                                   int af);
static struct hostent * ho_byaddr(struct irs_ho *this, const void *addr,
                                  int len, int af);
static struct hostent * ho_next(struct irs_ho *this);
static void             ho_rewind(struct irs_ho *this);
static void             ho_minimize(struct irs_ho *this);
static struct __res_state * ho_res_get(struct irs_ho *this);
static void             ho_res_set(struct irs_ho *this,
                                   struct __res_state *res,
                                   void (*free_res)(void *));
static struct addrinfo * ho_addrinfo(struct irs_ho *this, const char *name,
                                     const struct addrinfo *pai);

static size_t           ns_namelen(const char *);
static int              init(struct irs_ho *this);

/* Portability. */

#ifndef SEEK_SET
# define SEEK_SET 0
#endif

/* Public. */

struct irs_ho *
irs_lcl_ho(struct irs_acc *this) {
        struct irs_ho *ho;
        struct pvt *pvt;

        UNUSED(this);

        if (!(pvt = memget(sizeof *pvt))) {
                errno = ENOMEM;
                return (NULL);
        }
        memset(pvt, 0, sizeof *pvt);
        if (!(ho = memget(sizeof *ho))) {
                memput(pvt, sizeof *pvt);
                errno = ENOMEM;
                return (NULL);
        }
        memset(ho, 0x5e, sizeof *ho);
        ho->private = pvt;
        ho->close = ho_close;
        ho->byname = ho_byname;
        ho->byname2 = ho_byname2;
        ho->byaddr = ho_byaddr;
        ho->next = ho_next;
        ho->rewind = ho_rewind;
        ho->minimize = ho_minimize;
        ho->res_get = ho_res_get;
        ho->res_set = ho_res_set;
        ho->addrinfo = ho_addrinfo;
        return (ho);
}

/* Methods. */

static void
ho_close(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        ho_minimize(this);
        if (pvt->fp)
                (void) fclose(pvt->fp);
        if (pvt->res && pvt->free_res)
                (*pvt->free_res)(pvt->res);
        memput(pvt, sizeof *pvt);
        memput(this, sizeof *this);
}

static struct hostent *
ho_byname(struct irs_ho *this, const char *name) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct hostent *hp;

        if (init(this) == -1)
                return (NULL);

        if (pvt->res->options & RES_USE_INET6) {
                hp = ho_byname2(this, name, AF_INET6);
                if (hp)
                        return (hp);
        }
        return (ho_byname2(this, name, AF_INET));
}

static struct hostent *
ho_byname2(struct irs_ho *this, const char *name, int af) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct hostent *hp;
        char **hap;
        size_t n;

        if (init(this) == -1)
                return (NULL);

        ho_rewind(this);
        n = ns_namelen(name);
        while ((hp = ho_next(this)) != NULL) {
                size_t nn;

                if (hp->h_addrtype != af)
                        continue;
                nn = ns_namelen(hp->h_name);
                if (strncasecmp(hp->h_name, name, Max(n, nn)) == 0)
                        goto found;
                for (hap = hp->h_aliases; *hap; hap++) {
                        nn = ns_namelen(*hap);
                        if (strncasecmp(*hap, name, Max(n, nn)) == 0)
                                goto found;
                }
        }
 found:
        if (!hp) {
                RES_SET_H_ERRNO(pvt->res, HOST_NOT_FOUND);
                return (NULL);
        }
        RES_SET_H_ERRNO(pvt->res, NETDB_SUCCESS);
        return (hp);
}

static struct hostent *
ho_byaddr(struct irs_ho *this, const void *addr, int len, int af) {
        struct pvt *pvt = (struct pvt *)this->private;
        const u_char *uaddr = addr;
        struct hostent *hp;
        int size;

        if (init(this) == -1)
                return (NULL);

        if (af == AF_INET6 && len == IN6ADDRSZ &&
            (!memcmp(uaddr, mapped, sizeof mapped) ||
             !memcmp(uaddr, tunnelled, sizeof tunnelled))) {
                /* Unmap. */
                addr = (const u_char *)addr + sizeof mapped;
                uaddr += sizeof mapped;
                af = AF_INET;
                len = INADDRSZ;
        }
        switch (af) {
        case AF_INET:
                size = INADDRSZ;
                break;
        case AF_INET6:
                size = IN6ADDRSZ;
                break;
        default:
                errno = EAFNOSUPPORT;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                return (NULL);
        }
        if (size > len) {
                errno = EINVAL;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                return (NULL);
        }

        /*
         * Do the search.
         */
        ho_rewind(this);
        while ((hp = ho_next(this)) != NULL) {
                char **hap;

                for (hap = hp->h_addr_list; *hap; hap++) {
                        const u_char *taddr = (const u_char *)*hap;
                        int taf = hp->h_addrtype;
                        int tlen = hp->h_length;

                        if (taf == AF_INET6 && tlen == IN6ADDRSZ &&
                            (!memcmp(taddr, mapped, sizeof mapped) ||
                             !memcmp(taddr, tunnelled, sizeof tunnelled))) {
                                /* Unmap. */
                                taddr += sizeof mapped;
                                taf = AF_INET;
                                tlen = INADDRSZ;
                        }
                        if (taf == af && tlen == len &&
                            !memcmp(taddr, uaddr, tlen))
                                goto found;
                }
        }
 found:
        if (!hp) {
                RES_SET_H_ERRNO(pvt->res, HOST_NOT_FOUND);
                return (NULL);
        }
        RES_SET_H_ERRNO(pvt->res, NETDB_SUCCESS);
        return (hp);
}

static struct hostent *
ho_next(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;
        char *cp, **q, *p;
        char *bufp, *ndbuf, *dbuf = NULL;
        int c, af, len, bufsiz, offset;

        if (init(this) == -1)
                return (NULL);

        if (!pvt->fp)
                ho_rewind(this);
        if (!pvt->fp) {
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                return (NULL);
        }
        bufp = pvt->hostbuf;
        bufsiz = sizeof pvt->hostbuf;
        offset = 0;
 again:
        if (!(p = fgets(bufp + offset, bufsiz - offset, pvt->fp))) {
                RES_SET_H_ERRNO(pvt->res, HOST_NOT_FOUND);
                if (dbuf)
                        free(dbuf);
                return (NULL);
        }
        if (!strchr(p, '\n') && !feof(pvt->fp)) {
#define GROWBUF 1024
                /* allocate space for longer line */
                if (dbuf == NULL) {
                        if ((ndbuf = malloc(bufsiz + GROWBUF)) != NULL)
                                strcpy(ndbuf, bufp);
                } else
                        ndbuf = realloc(dbuf, bufsiz + GROWBUF);
                if (ndbuf) {
                        dbuf = ndbuf;
                        bufp = dbuf;
                        bufsiz += GROWBUF;
                        offset = strlen(dbuf);
                } else {
                        /* allocation failed; skip this long line */
                        while ((c = getc(pvt->fp)) != EOF)
                                if (c == '\n')
                                        break;
                        if (c != EOF)
                                ungetc(c, pvt->fp);
                }
                goto again;
        }

        p -= offset;
        offset = 0;

        if (*p == '#')
                goto again;
        if ((cp = strpbrk(p, "#\n")) != NULL)
                *cp = '\0';
        if (!(cp = strpbrk(p, " \t")))
                goto again;
        *cp++ = '\0';
        if (inet_pton(AF_INET6, p, pvt->host_addr) > 0) {
                af = AF_INET6;
                len = IN6ADDRSZ;
        } else if (inet_aton(p, (struct in_addr *)pvt->host_addr) > 0) {
                if (pvt->res->options & RES_USE_INET6) {
                        map_v4v6_address((char*)pvt->host_addr,
                                         (char*)pvt->host_addr);
                        af = AF_INET6;
                        len = IN6ADDRSZ;
                } else {
                        af = AF_INET;
                        len = INADDRSZ;
                }
        } else {
                goto again;
        }
        pvt->h_addr_ptrs[0] = (char *)pvt->host_addr;
        pvt->h_addr_ptrs[1] = NULL;
        pvt->host.h_addr_list = pvt->h_addr_ptrs;
        pvt->host.h_length = len;
        pvt->host.h_addrtype = af;
        while (*cp == ' ' || *cp == '\t')
                cp++;
        pvt->host.h_name = cp;
        q = pvt->host.h_aliases = pvt->host_aliases;
        if ((cp = strpbrk(cp, " \t")) != NULL)
                *cp++ = '\0';
        while (cp && *cp) {
                if (*cp == ' ' || *cp == '\t') {
                        cp++;
                        continue;
                }
                if (q < &pvt->host_aliases[MAXALIASES - 1])
                        *q++ = cp;
                if ((cp = strpbrk(cp, " \t")) != NULL)
                        *cp++ = '\0';
        }
        *q = NULL;
        if (dbuf)
                free(dbuf);
        RES_SET_H_ERRNO(pvt->res, NETDB_SUCCESS);
        return (&pvt->host);
}

static void
ho_rewind(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (pvt->fp) {
                if (fseek(pvt->fp, 0L, SEEK_SET) == 0)
                        return;
                (void)fclose(pvt->fp);
        }
        if (!(pvt->fp = fopen(_PATH_HOSTS, "r")))
                return;
        if (fcntl(fileno(pvt->fp), F_SETFD, 1) < 0) {
                (void)fclose(pvt->fp);
                pvt->fp = NULL;
        }
}

static void
ho_minimize(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (pvt->fp != NULL) {
                (void)fclose(pvt->fp);
                pvt->fp = NULL;
        }
        if (pvt->res)
                res_nclose(pvt->res);
}

static struct __res_state *
ho_res_get(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (!pvt->res) {
                struct __res_state *res;
                res = (struct __res_state *)malloc(sizeof *res);
                if (!res) {
                        errno = ENOMEM;
                        return (NULL);
                }
                memset(res, 0, sizeof *res);
                ho_res_set(this, res, free);
        }

        return (pvt->res);
}

static void
ho_res_set(struct irs_ho *this, struct __res_state *res,
                void (*free_res)(void *)) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (pvt->res && pvt->free_res) {
                res_nclose(pvt->res);
                (*pvt->free_res)(pvt->res);
        }

        pvt->res = res;
        pvt->free_res = free_res;
}

struct lcl_res_target {
        struct lcl_res_target *next;
        int family;
};

/* XXX */
extern struct addrinfo *hostent2addrinfo __P((struct hostent *,
                                              const struct addrinfo *pai));

static struct addrinfo *
ho_addrinfo(struct irs_ho *this, const char *name, const struct addrinfo *pai)
{
        struct pvt *pvt = (struct pvt *)this->private;
        struct hostent *hp;
        struct lcl_res_target q, q2, *p;
        struct addrinfo sentinel, *cur;

        memset(&q, 0, sizeof(q2));
        memset(&q2, 0, sizeof(q2));
        memset(&sentinel, 0, sizeof(sentinel));
        cur = &sentinel;

        switch(pai->ai_family) {
        case AF_UNSPEC:         /*%< INET6 then INET4 */
                q.family = AF_INET6;
                q.next = &q2;
                q2.family = AF_INET;
                break;
        case AF_INET6:
                q.family = AF_INET6;
                break;
        case AF_INET:
                q.family = AF_INET;
                break;
        default:
                RES_SET_H_ERRNO(pvt->res, NO_RECOVERY); /*%< ??? */
                return(NULL);
        }

        for (p = &q; p; p = p->next) {
                struct addrinfo *ai;

                hp = (*this->byname2)(this, name, p->family);
                if (hp == NULL) {
                        /* byname2 should've set an appropriate error */
                        continue;
                }
                if ((hp->h_name == NULL) || (hp->h_name[0] == 0) ||
                    (hp->h_addr_list[0] == NULL)) {
                        RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
                        continue;
                }

                ai = hostent2addrinfo(hp, pai);
                if (ai) {
                        cur->ai_next = ai;
                        while (cur->ai_next)
                                cur = cur->ai_next;
                }
        }

        if (sentinel.ai_next == NULL)
                RES_SET_H_ERRNO(pvt->res, HOST_NOT_FOUND);

        return(sentinel.ai_next);
}

/* Private. */

static size_t
ns_namelen(const char *s) {
        int i;

        for (i = strlen(s); i > 0 && s[i-1] == '.'; i--)
                (void)NULL;
        return ((size_t) i);
}

static int
init(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (!pvt->res && !ho_res_get(this))
                return (-1);
        if (((pvt->res->options & RES_INIT) == 0U) &&
            res_ninit(pvt->res) == -1)
                return (-1);
        return (0);
}

/*! \file */