source: trunk/third/evolution/e-util/e-host-utils.c @ 16787

/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/* e-host-utils.c
 *
 * Copyright (C) 2001  Ximian, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Author: Chris Toshok
 */

#include <config.h>
#include <glib.h>
#include "e-host-utils.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#ifndef HAVE_GETHOSTBYNAME_R
G_LOCK_DEFINE_STATIC (gethost_mutex);
#endif

/**
 * e_gethostbyname_r:
 * @name: the host to resolve
 * @host: a buffer pointing to a struct hostent to use for storage
 * @buf: a buffer to use for hostname storage
 * @buflen: the size of @buf
 * @herr: a pointer to a variable to store an error code in
 *
 * Resolves the hostname @name, in a hopefully-reentrant fashion.
 *
 * Return value: 0 on success, ERANGE if @buflen is too small,
 * "something else" otherwise (in which case *@herr will be set to
 * one of the gethostbyname() error codes).
 **/
int
e_gethostbyname_r (const char *name, struct hostent *host,
                   char *buf, int buflen, int *herr)
{
#ifdef HAVE_GETHOSTBYNAME_R
#ifdef GETHOSTBYNAME_R_FIVE_ARGS
        if (gethostbyname_r(name, host, buf, buflen, herr))
                return 0;
        else
                return errno;
#else
        struct hostent *hp;
        int retval;

        retval = gethostbyname_r(name, host, buf, buflen, &hp, herr);
        if (hp != NULL)
                *herr = 0;
        return retval;
#endif
#else
        int i;
        char *p;
        struct hostent *h;
        int req_length;
        int num_aliases = 0, num_addrs = 0;

        G_LOCK (gethost_mutex);

        h = gethostbyname (name);

        if (!h) {
                *herr = h_errno;
                G_UNLOCK (gethost_mutex);
                return -1;
        }

        /* check to make sure we have enough room in our buffer */
        req_length = 0;
        if (h->h_aliases) {
                for (i = 0; h->h_aliases[i]; i ++)
                        req_length += strlen (h->h_aliases[i]) + 1;
                num_aliases = i;
        }
        if (h->h_addr_list) {
                for (i = 0; h->h_addr_list[i]; i ++)
                        req_length += h->h_length;
                num_addrs = i;
        }

        req_length += sizeof (char*) * (num_aliases + 1);
        req_length += sizeof (char*) * (num_addrs + 1);
        req_length += strlen (h->h_name) + 1;

        if (buflen < req_length) {
                *herr = ERANGE;
                G_UNLOCK (gethost_mutex);
                return ERANGE;
        }

        /* we store the alias/addr pointers in the buffer - figure out
           their addresses here. */
        p = buf;
        if (num_aliases) {
                host->h_aliases = (char**)p;
                p += sizeof (char*) * (num_aliases + 1);
        }
        else
                host->h_aliases = NULL;
        if (num_addrs) {
                host->h_addr_list = (char**)p;
                p += sizeof(char*) * (num_addrs + 1);
        }
        else
                host->h_addr_list = NULL;

        /* copy the host name into the buffer */
        host->h_name = p;
        strcpy (p, h->h_name);
        p += strlen (h->h_name) + 1;
        host->h_addrtype = h->h_addrtype;
        host->h_length = h->h_length;

        /* copy the aliases/addresses into the buffer, and assign the
           pointers into the hostent */
        *p = 0;
        if (num_aliases) {
                for (i = 0; i < num_aliases; i ++) {
                        strcpy (p, h->h_aliases[i]);
                        host->h_aliases[i] = p;
                        p += strlen (h->h_aliases[i]);
                }
                host->h_aliases[num_aliases] = NULL;
        }

        if (num_addrs) {
                for (i = 0; i < num_addrs; i ++) {
                        memcpy (p, h->h_addr_list[i], h->h_length);
                        host->h_addr_list[i] = p;
                        p += h->h_length;
                }
                host->h_addr_list[num_addrs] = NULL;
        }

        G_UNLOCK (gethost_mutex);

        return 0;
#endif
}