ext/sockets/multicast.c

/*
   +----------------------------------------------------------------------+
   | PHP Version 7                                                        |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997-2018 The PHP Group                                |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.php.net/license/3_01.txt                                  |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Gustavo Lopes    <cataphract@php.net>                       |
   +----------------------------------------------------------------------+
 */

/* $Id$ */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "php.h"

#include "php_network.h"
#ifdef PHP_WIN32
# include "windows_common.h"
#else
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#endif

#include "php_sockets.h"
#include "multicast.h"
#include "sockaddr_conv.h"
#include "main/php_network.h"


enum source_op {
	JOIN_SOURCE,
	LEAVE_SOURCE,
	BLOCK_SOURCE,
	UNBLOCK_SOURCE
};

static int _php_mcast_join_leave(php_socket *sock, int level, struct sockaddr *group, socklen_t group_len, unsigned int if_index, int join);
#ifdef HAS_MCAST_EXT
static int _php_mcast_source_op(php_socket *sock, int level, struct sockaddr *group, socklen_t group_len, struct sockaddr *source, socklen_t source_len, unsigned int if_index, enum source_op sop);
#endif

#ifdef RFC3678_API
static int _php_source_op_to_rfc3678_op(enum source_op sop);
#elif HAS_MCAST_EXT
static const char *_php_source_op_to_string(enum source_op sop);
static int _php_source_op_to_ipv4_op(enum source_op sop);
#endif

int php_string_to_if_index(const char *val, unsigned *out)
{
#if HAVE_IF_NAMETOINDEX
	unsigned int ind;

	ind = if_nametoindex(val);
	if (ind == 0) {
		php_error_docref(NULL, E_WARNING,
			"no interface with name \"%s\" could be found", val);
		return FAILURE;
	} else {
		*out = ind;
		return SUCCESS;
	}
#else
	php_error_docref(NULL, E_WARNING,
			"this platform does not support looking up an interface by "
			"name, an integer interface index must be supplied instead");
	return FAILURE;
#endif
}

static int php_get_if_index_from_zval(zval *val, unsigned *out)
{
	int ret;

	if (Z_TYPE_P(val) == IS_LONG) {
		if (Z_LVAL_P(val) < 0 || (zend_ulong)Z_LVAL_P(val) > UINT_MAX) {
			php_error_docref(NULL, E_WARNING,
				"the interface index cannot be negative or larger than %u;"
				" given " ZEND_LONG_FMT, UINT_MAX, Z_LVAL_P(val));
			ret = FAILURE;
		} else {
			*out = Z_LVAL_P(val);
			ret = SUCCESS;
		}
	} else {
		if (Z_REFCOUNTED_P(val)) {
			Z_ADDREF_P(val);
		}
		convert_to_string_ex(val);
		ret = php_string_to_if_index(Z_STRVAL_P(val), out);
		zval_ptr_dtor(val);
	}

	return ret;
}


static int php_get_if_index_from_array(const HashTable *ht, const char *key,
	php_socket *sock, unsigned int *if_index)
{
	zval *val;

	if ((val = zend_hash_str_find(ht, key, strlen(key))) == NULL) {
		*if_index = 0; /* default: 0 */
		return SUCCESS;
	}

	return php_get_if_index_from_zval(val, if_index);
}

static int php_get_address_from_array(const HashTable *ht, const char *key,
	php_socket *sock, php_sockaddr_storage *ss, socklen_t *ss_len)
{
	zval *val;

	if ((val = zend_hash_str_find(ht, key, strlen(key))) == NULL) {
		php_error_docref(NULL, E_WARNING, "no key \"%s\" passed in optval", key);
		return FAILURE;
	}
	if (Z_REFCOUNTED_P(val)) {
		Z_ADDREF_P(val);
	}
	convert_to_string_ex(val);
	if (!php_set_inet46_addr(ss, ss_len, Z_STRVAL_P(val), sock)) {
		zval_ptr_dtor(val);
		return FAILURE;
	}
	zval_ptr_dtor(val);
	return SUCCESS;
}

static int php_do_mcast_opt(php_socket *php_sock, int level, int optname, zval *arg4)
{
	HashTable		 		*opt_ht;
	unsigned int			if_index;
	int						retval;
	int (*mcast_req_fun)(php_socket *, int, struct sockaddr *, socklen_t,
		unsigned);
#ifdef HAS_MCAST_EXT
	int (*mcast_sreq_fun)(php_socket *, int, struct sockaddr *, socklen_t,
		struct sockaddr *, socklen_t, unsigned);
#endif

	switch (optname) {
	case PHP_MCAST_JOIN_GROUP:
		mcast_req_fun = &php_mcast_join;
		goto mcast_req_fun;
	case PHP_MCAST_LEAVE_GROUP:
		{
			php_sockaddr_storage	group = {0};
			socklen_t				glen;

			mcast_req_fun = &php_mcast_leave;
mcast_req_fun:
			convert_to_array_ex(arg4);
			opt_ht = Z_ARRVAL_P(arg4);

			if (php_get_address_from_array(opt_ht, "group", php_sock, &group,
				&glen) == FAILURE) {
					return FAILURE;
			}
			if (php_get_if_index_from_array(opt_ht, "interface", php_sock,
				&if_index) == FAILURE) {
					return FAILURE;
			}

			retval = mcast_req_fun(php_sock, level, (struct sockaddr*)&group,
				glen, if_index);
			break;
		}

#ifdef HAS_MCAST_EXT
	case PHP_MCAST_BLOCK_SOURCE:
		mcast_sreq_fun = &php_mcast_block_source;
		goto mcast_sreq_fun;
	case PHP_MCAST_UNBLOCK_SOURCE:
		mcast_sreq_fun = &php_mcast_unblock_source;
		goto mcast_sreq_fun;
	case PHP_MCAST_JOIN_SOURCE_GROUP:
		mcast_sreq_fun = &php_mcast_join_source;
		goto mcast_sreq_fun;
	case PHP_MCAST_LEAVE_SOURCE_GROUP:
		{
			php_sockaddr_storage	group = {0},
									source = {0};
			socklen_t				glen,
									slen;

			mcast_sreq_fun = &php_mcast_leave_source;
		mcast_sreq_fun:
			convert_to_array_ex(arg4);
			opt_ht = Z_ARRVAL_P(arg4);

			if (php_get_address_from_array(opt_ht, "group", php_sock, &group,
					&glen) == FAILURE) {
				return FAILURE;
			}
			if (php_get_address_from_array(opt_ht, "source", php_sock, &source,
					&slen) == FAILURE) {
				return FAILURE;
			}
			if (php_get_if_index_from_array(opt_ht, "interface", php_sock,
					&if_index) == FAILURE) {
				return FAILURE;
			}

			retval = mcast_sreq_fun(php_sock, level, (struct sockaddr*)&group,
					glen, (struct sockaddr*)&source, slen, if_index);
			break;
		}
#endif
	default:
		php_error_docref(NULL, E_WARNING,
			"unexpected option in php_do_mcast_opt (level %d, option %d). "
			"This is a bug.", level, optname);
		return FAILURE;
	}

	if (retval != 0) {
		if (retval != -2) { /* error, but message already emitted */
			PHP_SOCKET_ERROR(php_sock, "unable to set socket option", errno);
		}
		return FAILURE;
	}
	return SUCCESS;
}

int php_do_setsockopt_ip_mcast(php_socket *php_sock,
							   int level,
							   int optname,
							   zval *arg4)
{
	unsigned int	if_index;
	struct in_addr	if_addr;
	void 			*opt_ptr;
	socklen_t		optlen;
	unsigned char	ipv4_mcast_ttl_lback;
	int				retval;

	switch (optname) {
	case PHP_MCAST_JOIN_GROUP:
	case PHP_MCAST_LEAVE_GROUP:
#ifdef HAS_MCAST_EXT
	case PHP_MCAST_BLOCK_SOURCE:
	case PHP_MCAST_UNBLOCK_SOURCE:
	case PHP_MCAST_JOIN_SOURCE_GROUP:
	case PHP_MCAST_LEAVE_SOURCE_GROUP:
#endif
		if (php_do_mcast_opt(php_sock, level, optname, arg4) == FAILURE) {
			return FAILURE;
		} else {
			return SUCCESS;
		}

	case IP_MULTICAST_IF:
		if (php_get_if_index_from_zval(arg4, &if_index) == FAILURE) {
			return FAILURE;
		}

		if (php_if_index_to_addr4(if_index, php_sock, &if_addr) == FAILURE) {
			return FAILURE;
		}
		opt_ptr = &if_addr;
		optlen	= sizeof(if_addr);
		goto dosockopt;

	case IP_MULTICAST_LOOP:
		convert_to_boolean_ex(arg4);
		ipv4_mcast_ttl_lback = (unsigned char) (Z_TYPE_P(arg4) == IS_TRUE);
		goto ipv4_loop_ttl;

	case IP_MULTICAST_TTL:
		convert_to_long_ex(arg4);
		if (Z_LVAL_P(arg4) < 0L || Z_LVAL_P(arg4) > 255L) {
			php_error_docref(NULL, E_WARNING,
					"Expected a value between 0 and 255");
			return FAILURE;
		}
		ipv4_mcast_ttl_lback = (unsigned char) Z_LVAL_P(arg4);
ipv4_loop_ttl:
		opt_ptr = &ipv4_mcast_ttl_lback;
		optlen	= sizeof(ipv4_mcast_ttl_lback);
		goto dosockopt;
	}

	return 1;

dosockopt:
	retval = setsockopt(php_sock->bsd_socket, level, optname, opt_ptr, optlen);
	if (retval != 0) {
		PHP_SOCKET_ERROR(php_sock, "unable to set socket option", errno);
		return FAILURE;
	}

	return SUCCESS;
}

int php_do_setsockopt_ipv6_mcast(php_socket *php_sock,
								 int level,
								 int optname,
								 zval *arg4)
{
	unsigned int	if_index;
	void			*opt_ptr;
	socklen_t		optlen;
	int				ov;
	int				retval;

	switch (optname) {
	case PHP_MCAST_JOIN_GROUP:
	case PHP_MCAST_LEAVE_GROUP:
#ifdef HAS_MCAST_EXT
	case PHP_MCAST_BLOCK_SOURCE:
	case PHP_MCAST_UNBLOCK_SOURCE:
	case PHP_MCAST_JOIN_SOURCE_GROUP:
	case PHP_MCAST_LEAVE_SOURCE_GROUP:
#endif
		if (php_do_mcast_opt(php_sock, level, optname, arg4) == FAILURE) {
			return FAILURE;
		} else {
			return SUCCESS;
		}

	case IPV6_MULTICAST_IF:
		if (php_get_if_index_from_zval(arg4, &if_index) == FAILURE) {
			return FAILURE;
		}

		opt_ptr = &if_index;
		optlen	= sizeof(if_index);
		goto dosockopt;

	case IPV6_MULTICAST_LOOP:
		convert_to_boolean_ex(arg4);
		ov = (int) Z_TYPE_P(arg4) == IS_TRUE;
		goto ipv6_loop_hops;
	case IPV6_MULTICAST_HOPS:
		convert_to_long_ex(arg4);
		if (Z_LVAL_P(arg4) < -1L || Z_LVAL_P(arg4) > 255L) {
			php_error_docref(NULL, E_WARNING,
					"Expected a value between -1 and 255");
			return FAILURE;
		}
		ov = (int) Z_LVAL_P(arg4);
ipv6_loop_hops:
		opt_ptr = &ov;
		optlen	= sizeof(ov);
		goto dosockopt;
	}

	return 1; /* not handled */

dosockopt:
	retval = setsockopt(php_sock->bsd_socket, level, optname, opt_ptr, optlen);
	if (retval != 0) {
		PHP_SOCKET_ERROR(php_sock, "unable to set socket option", errno);
		return FAILURE;
	}

	return SUCCESS;
}

int php_mcast_join(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	unsigned int if_index)
{
	return _php_mcast_join_leave(sock, level, group, group_len, if_index, 1);
}

int php_mcast_leave(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	unsigned int if_index)
{
	return _php_mcast_join_leave(sock, level, group, group_len, if_index, 0);
}

#ifdef HAS_MCAST_EXT
int php_mcast_join_source(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	struct sockaddr *source,
	socklen_t source_len,
	unsigned int if_index)
{
	return _php_mcast_source_op(sock, level, group, group_len, source, source_len, if_index, JOIN_SOURCE);
}

int php_mcast_leave_source(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	struct sockaddr *source,
	socklen_t source_len,
	unsigned int if_index)
{
	return _php_mcast_source_op(sock, level, group, group_len, source, source_len, if_index, LEAVE_SOURCE);
}

int php_mcast_block_source(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	struct sockaddr *source,
	socklen_t source_len,
	unsigned int if_index)
{
	return _php_mcast_source_op(sock, level, group, group_len, source, source_len, if_index, BLOCK_SOURCE);
}

int php_mcast_unblock_source(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	struct sockaddr *source,
	socklen_t source_len,
	unsigned int if_index)
{
	return _php_mcast_source_op(sock, level, group, group_len, source, source_len, if_index, UNBLOCK_SOURCE);
}
#endif /* HAS_MCAST_EXT */


static int _php_mcast_join_leave(
	php_socket *sock,
	int level,
	struct sockaddr *group, /* struct sockaddr_in/sockaddr_in6 */
	socklen_t group_len,
	unsigned int if_index,
	int join)
{
#ifdef RFC3678_API
	struct group_req greq = {0};

	memcpy(&greq.gr_group, group, group_len);
	assert(greq.gr_group.ss_family != 0); /* the caller has set this */
	greq.gr_interface = if_index;

	return setsockopt(sock->bsd_socket, level,
			join ? MCAST_JOIN_GROUP : MCAST_LEAVE_GROUP, (char*)&greq,
			sizeof(greq));
#else
	if (sock->type == AF_INET) {
		struct ip_mreq mreq = {0};
		struct in_addr addr;

		assert(group_len == sizeof(struct sockaddr_in));

		if (if_index != 0) {
			if (php_if_index_to_addr4(if_index, sock, &addr) ==
					FAILURE)
				return -2; /* failure, but notice already emitted */
			mreq.imr_interface = addr;
		} else {
			mreq.imr_interface.s_addr = htonl(INADDR_ANY);
		}
		mreq.imr_multiaddr = ((struct sockaddr_in*)group)->sin_addr;
		return setsockopt(sock->bsd_socket, level,
				join ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, (char*)&mreq,
				sizeof(mreq));
	}
#if HAVE_IPV6
	else if (sock->type == AF_INET6) {
		struct ipv6_mreq mreq = {0};

		assert(group_len == sizeof(struct sockaddr_in6));

		mreq.ipv6mr_multiaddr = ((struct sockaddr_in6*)group)->sin6_addr;
		mreq.ipv6mr_interface = if_index;

		return setsockopt(sock->bsd_socket, level,
				join ? IPV6_JOIN_GROUP : IPV6_LEAVE_GROUP, (char*)&mreq,
				sizeof(mreq));
	}
#endif
	else {
		php_error_docref(NULL, E_WARNING,
			"Option %s is inapplicable to this socket type",
			join ? "MCAST_JOIN_GROUP" : "MCAST_LEAVE_GROUP");
		return -2;
	}
#endif
}

#ifdef HAS_MCAST_EXT
static int _php_mcast_source_op(
	php_socket *sock,
	int level,
	struct sockaddr *group,
	socklen_t group_len,
	struct sockaddr *source,
	socklen_t source_len,
	unsigned int if_index,
	enum source_op sop)
{
#ifdef RFC3678_API
	struct group_source_req gsreq = {0};

	memcpy(&gsreq.gsr_group, group, group_len);
	assert(gsreq.gsr_group.ss_family != 0);
	memcpy(&gsreq.gsr_source, source, source_len);
	assert(gsreq.gsr_source.ss_family != 0);
	gsreq.gsr_interface = if_index;

	return setsockopt(sock->bsd_socket, level,
			_php_source_op_to_rfc3678_op(sop), (char*)&gsreq, sizeof(gsreq));
#else
	if (sock->type == AF_INET) {
		struct ip_mreq_source mreqs = {0};
		struct in_addr addr;

		mreqs.imr_multiaddr = ((struct sockaddr_in*)group)->sin_addr;
		mreqs.imr_sourceaddr =  ((struct sockaddr_in*)source)->sin_addr;

		assert(group_len == sizeof(struct sockaddr_in));
		assert(source_len == sizeof(struct sockaddr_in));

		if (if_index != 0) {
			if (php_if_index_to_addr4(if_index, sock, &addr) ==
					FAILURE)
				return -2; /* failure, but notice already emitted */
			mreqs.imr_interface = addr;
		} else {
			mreqs.imr_interface.s_addr = htonl(INADDR_ANY);
		}

		return setsockopt(sock->bsd_socket, level,
				_php_source_op_to_ipv4_op(sop), (char*)&mreqs, sizeof(mreqs));
	}
#if HAVE_IPV6
	else if (sock->type == AF_INET6) {
		php_error_docref(NULL, E_WARNING,
			"This platform does not support %s for IPv6 sockets",
			_php_source_op_to_string(sop));
		return -2;
	}
#endif
	else {
		php_error_docref(NULL, E_WARNING,
			"Option %s is inapplicable to this socket type",
			_php_source_op_to_string(sop));
		return -2;
	}
#endif
}

#if RFC3678_API
static int _php_source_op_to_rfc3678_op(enum source_op sop)
{
	switch (sop) {
	case JOIN_SOURCE:
		return MCAST_JOIN_SOURCE_GROUP;
	case LEAVE_SOURCE:
		return MCAST_LEAVE_SOURCE_GROUP;
	case BLOCK_SOURCE:
		return MCAST_BLOCK_SOURCE;
	case UNBLOCK_SOURCE:
		return MCAST_UNBLOCK_SOURCE;
	}

	assert(0);
	return 0;
}
#else
static const char *_php_source_op_to_string(enum source_op sop)
{
	switch (sop) {
	case JOIN_SOURCE:
		return "MCAST_JOIN_SOURCE_GROUP";
	case LEAVE_SOURCE:
		return "MCAST_LEAVE_SOURCE_GROUP";
	case BLOCK_SOURCE:
		return "MCAST_BLOCK_SOURCE";
	case UNBLOCK_SOURCE:
		return "MCAST_UNBLOCK_SOURCE";
	}

	assert(0);
	return "";
}

static int _php_source_op_to_ipv4_op(enum source_op sop)
{
	switch (sop) {
	case JOIN_SOURCE:
		return IP_ADD_SOURCE_MEMBERSHIP;
	case LEAVE_SOURCE:
		return IP_DROP_SOURCE_MEMBERSHIP;
	case BLOCK_SOURCE:
		return IP_BLOCK_SOURCE;
	case UNBLOCK_SOURCE:
		return IP_UNBLOCK_SOURCE;
	}

	assert(0);
	return 0;
}
#endif

#endif /* HAS_MCAST_EXT */

#ifdef PHP_WIN32
int php_if_index_to_addr4(unsigned if_index, php_socket *php_sock, struct in_addr *out_addr)
{
	MIB_IPADDRTABLE *addr_table;
    ULONG size;
    DWORD retval;
	DWORD i;

	(void) php_sock; /* not necessary */

	if (if_index == 0) {
		out_addr->s_addr = INADDR_ANY;
		return SUCCESS;
	}

	size = 4 * (sizeof *addr_table);
	addr_table = emalloc(size);
retry:
	retval = GetIpAddrTable(addr_table, &size, 0);
	if (retval == ERROR_INSUFFICIENT_BUFFER) {
		efree(addr_table);
		addr_table = emalloc(size);
		goto retry;
	}
	if (retval != NO_ERROR) {
		efree(addr_table);
		php_error_docref(NULL, E_WARNING,
			"GetIpAddrTable failed with error %lu", retval);
		return FAILURE;
	}
	for (i = 0; i < addr_table->dwNumEntries; i++) {
		MIB_IPADDRROW r = addr_table->table[i];
		if (r.dwIndex == if_index) {
			out_addr->s_addr = r.dwAddr;
			efree(addr_table);
			return SUCCESS;
		}
	}
	efree(addr_table);
	php_error_docref(NULL, E_WARNING,
		"No interface with index %u was found", if_index);
	return FAILURE;
}

int php_add4_to_if_index(struct in_addr *addr, php_socket *php_sock, unsigned *if_index)
{
	MIB_IPADDRTABLE *addr_table;
    ULONG size;
    DWORD retval;
	DWORD i;

	(void) php_sock; /* not necessary */

	if (addr->s_addr == INADDR_ANY) {
		*if_index = 0;
		return SUCCESS;
	}

	size = 4 * (sizeof *addr_table);
	addr_table = emalloc(size);
retry:
	retval = GetIpAddrTable(addr_table, &size, 0);
	if (retval == ERROR_INSUFFICIENT_BUFFER) {
		efree(addr_table);
		addr_table = emalloc(size);
		goto retry;
	}
	if (retval != NO_ERROR) {
		efree(addr_table);
		php_error_docref(NULL, E_WARNING,
			"GetIpAddrTable failed with error %lu", retval);
		return FAILURE;
	}
	for (i = 0; i < addr_table->dwNumEntries; i++) {
		MIB_IPADDRROW r = addr_table->table[i];
		if (r.dwAddr == addr->s_addr) {
			*if_index = r.dwIndex;
			efree(addr_table);
			return SUCCESS;
		}
	}
	efree(addr_table);

	{
		char addr_str[17] = {0};
		inet_ntop(AF_INET, addr, addr_str, sizeof(addr_str));
		php_error_docref(NULL, E_WARNING,
			"The interface with IP address %s was not found", addr_str);
	}
	return FAILURE;
}

#else

int php_if_index_to_addr4(unsigned if_index, php_socket *php_sock, struct in_addr *out_addr)
{
	struct ifreq if_req;

	if (if_index == 0) {
		out_addr->s_addr = INADDR_ANY;
		return SUCCESS;
	}

#if !defined(ifr_ifindex) && defined(ifr_index)
#define ifr_ifindex ifr_index
#endif

#if defined(SIOCGIFNAME)
	if_req.ifr_ifindex = if_index;
	if (ioctl(php_sock->bsd_socket, SIOCGIFNAME, &if_req) == -1) {
#elif defined(HAVE_IF_INDEXTONAME)
	if (if_indextoname(if_index, if_req.ifr_name) == NULL) {
#else
#error Neither SIOCGIFNAME nor if_indextoname are available
#endif
		php_error_docref(NULL, E_WARNING,
			"Failed obtaining address for interface %u: error %d", if_index, errno);
		return FAILURE;
	}

	if (ioctl(php_sock->bsd_socket, SIOCGIFADDR, &if_req) == -1) {
		php_error_docref(NULL, E_WARNING,
			"Failed obtaining address for interface %u: error %d", if_index, errno);
		return FAILURE;
	}

	memcpy(out_addr, &((struct sockaddr_in *) &if_req.ifr_addr)->sin_addr,
		sizeof *out_addr);
	return SUCCESS;
}

int php_add4_to_if_index(struct in_addr *addr, php_socket *php_sock, unsigned *if_index)
{
	struct ifconf	if_conf = {0};
	char			*buf = NULL,
					*p;
	int				size = 0,
					lastsize = 0;
	size_t			entry_len;

	if (addr->s_addr == INADDR_ANY) {
		*if_index = 0;
		return SUCCESS;
	}

	for(;;) {
		size += 5 * sizeof(struct ifreq);
		buf = ecalloc(size, 1);
		if_conf.ifc_len = size;
		if_conf.ifc_buf = buf;

		if (ioctl(php_sock->bsd_socket, SIOCGIFCONF, (char*)&if_conf) == -1 &&
				(errno != EINVAL || lastsize != 0)) {
			php_error_docref(NULL, E_WARNING,
				"Failed obtaining interfaces list: error %d", errno);
			goto err;
		}

		if (if_conf.ifc_len == lastsize)
			/* not increasing anymore */
			break;
		else {
			lastsize = if_conf.ifc_len;
			efree(buf);
			buf = NULL;
		}
	}

	for (p = if_conf.ifc_buf;
		 p < if_conf.ifc_buf + if_conf.ifc_len;
		 p += entry_len) {
		struct ifreq *cur_req;

		/* let's hope the pointer is aligned */
		cur_req = (struct ifreq*) p;

#ifdef HAVE_SOCKADDR_SA_LEN
		entry_len = cur_req->ifr_addr.sa_len + sizeof(cur_req->ifr_name);
#else
		/* if there's no sa_len, assume the ifr_addr field is a sockaddr */
		entry_len = sizeof(struct sockaddr) + sizeof(cur_req->ifr_name);
#endif
		entry_len = MAX(entry_len, sizeof(*cur_req));

		if ((((struct sockaddr*)&cur_req->ifr_addr)->sa_family == AF_INET) &&
				(((struct sockaddr_in*)&cur_req->ifr_addr)->sin_addr.s_addr ==
					addr->s_addr)) {
#if defined(SIOCGIFINDEX)
			if (ioctl(php_sock->bsd_socket, SIOCGIFINDEX, (char*)cur_req)
					== -1) {
#elif defined(HAVE_IF_NAMETOINDEX)
			unsigned index_tmp;
			if ((index_tmp = if_nametoindex(cur_req->ifr_name)) == 0) {
#else
#error Neither SIOCGIFINDEX nor if_nametoindex are available
#endif
				php_error_docref(NULL, E_WARNING,
					"Error converting interface name to index: error %d",
					errno);
				goto err;
			} else {
#if defined(SIOCGIFINDEX)
				*if_index = cur_req->ifr_ifindex;
#else
				*if_index = index_tmp;
#endif
				efree(buf);
				return SUCCESS;
			}
		}
	}

	{
		char addr_str[17] = {0};
		inet_ntop(AF_INET, addr, addr_str, sizeof(addr_str));
		php_error_docref(NULL, E_WARNING,
			"The interface with IP address %s was not found", addr_str);
	}

err:
	if (buf != NULL)
		efree(buf);
	return FAILURE;
}
#endif