path: root/e-util/e-host-utils.c

/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/* e-host-utils.c
 *
 * Copyright (C) 2001  Helix Code, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * 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>

G_LOCK_DEFINE_STATIC (gethost_mutex);

/**
 * 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
}