evolution/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  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
}