library/net.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  TCP networking functions
  *
  *  Copyright (C) 2006-2014, Brainspark B.V.
  *
  *  This file is part of PolarSSL (http://www.polarssl.org)
  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
  *
  *  All rights reserved.
  *
  *  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.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */

 #if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
 #else
 #include POLARSSL_CONFIG_FILE
 #endif

 #if defined(POLARSSL_NET_C)

 #include "polarssl/net.h"

 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
     !defined(EFI32)

 #if defined(POLARSSL_HAVE_IPV6)
 #ifdef _WIN32_WINNT
 #undef _WIN32_WINNT
 #endif
 /* Enables getaddrinfo() & Co */
 #define _WIN32_WINNT 0x0501
 #include <ws2tcpip.h>
 #endif

 #include <winsock2.h>
 #include <windows.h>

 #if defined(_MSC_VER)
 #if defined(_WIN32_WCE)
 #pragma comment( lib, "ws2.lib" )
 #else
 #pragma comment( lib, "ws2_32.lib" )
 #endif
 #endif /* _MSC_VER */

 #define read(fd,buf,len)        recv(fd,(char*)buf,(int) len,0)
 #define write(fd,buf,len)       send(fd,(char*)buf,(int) len,0)
 #define close(fd)               closesocket(fd)

 static int wsa_init_done = 0;

 #else /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */

 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #if defined(POLARSSL_HAVE_TIME)
 #include <sys/time.h>
 #endif
 #include <unistd.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <netdb.h>
 #include <errno.h>

 #if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) ||  \
     defined(__DragonFly__)
 #include <sys/endian.h>
 #elif defined(__APPLE__) || defined(HAVE_MACHINE_ENDIAN_H) ||   \
       defined(EFIX64) || defined(EFI32)
 #include <machine/endian.h>
 #elif defined(sun)
 #include <sys/isa_defs.h>
 #elif defined(_AIX) || defined(HAVE_ARPA_NAMESER_COMPAT_H)
 #include <arpa/nameser_compat.h>
 #else
 #include <endian.h>
 #endif

 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */

 #include <stdlib.h>
 #include <stdio.h>

 #if defined(_MSC_VER) && !defined  snprintf && !defined(EFIX64) && \
     !defined(EFI32)
 #define  snprintf  _snprintf
 #endif

 #if defined(POLARSSL_HAVE_TIME)
 #include <time.h>
 #endif

 #if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
 #include <basetsd.h>
 typedef UINT32 uint32_t;
 #else
 #include <inttypes.h>
 #endif

 /*
  * htons() is not always available.
  * By default go for LITTLE_ENDIAN variant. Otherwise hope for _BYTE_ORDER and
  * __BIG_ENDIAN to help determine endianness.
  */
 #if defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) &&                   \
     __BYTE_ORDER == __BIG_ENDIAN
 #define POLARSSL_HTONS(n) (n)
 #define POLARSSL_HTONL(n) (n)
 #else
 #define POLARSSL_HTONS(n) ((((unsigned short)(n) & 0xFF      ) << 8 ) | \
                            (((unsigned short)(n) & 0xFF00    ) >> 8 ))
 #define POLARSSL_HTONL(n) ((((unsigned long )(n) & 0xFF      ) << 24) | \
                            (((unsigned long )(n) & 0xFF00    ) << 8 ) | \
                            (((unsigned long )(n) & 0xFF0000  ) >> 8 ) | \
                            (((unsigned long )(n) & 0xFF000000) >> 24))
 #endif

 unsigned short net_htons( unsigned short n );
 unsigned long  net_htonl( unsigned long  n );
 #define net_htons(n) POLARSSL_HTONS(n)
 #define net_htonl(n) POLARSSL_HTONL(n)

 /*
  * Prepare for using the sockets interface
  */
 static int net_prepare( void )
 {
 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
     WSADATA wsaData;

     if( wsa_init_done == 0 )
     {
         if( WSAStartup( MAKEWORD(2,0), &wsaData ) != 0 )
             return( POLARSSL_ERR_NET_SOCKET_FAILED );

         wsa_init_done = 1;
     }
 #else
 #if !defined(EFIX64) && !defined(EFI32)
     signal( SIGPIPE, SIG_IGN );
 #endif
 #endif
     return( 0 );
 }

 /*
  * Initiate a TCP connection with host:port
  */
 int net_connect( int *fd, const char *host, int port )
 {
 #if defined(POLARSSL_HAVE_IPV6)
     int ret;
     struct addrinfo hints, *addr_list, *cur;
     char port_str[6];

     if( ( ret = net_prepare() ) != 0 )
         return( ret );

     /* getaddrinfo expects port as a string */
     memset( port_str, 0, sizeof( port_str ) );
     snprintf( port_str, sizeof( port_str ), "%d", port );

     /* Do name resolution with both IPv6 and IPv4, but only TCP */
     memset( &hints, 0, sizeof( hints ) );
     hints.ai_family = AF_UNSPEC;
     hints.ai_socktype = SOCK_STREAM;
     hints.ai_protocol = IPPROTO_TCP;

     if( getaddrinfo( host, port_str, &hints, &addr_list ) != 0 )
         return( POLARSSL_ERR_NET_UNKNOWN_HOST );

     /* Try the sockaddrs until a connection succeeds */
     ret = POLARSSL_ERR_NET_UNKNOWN_HOST;
     for( cur = addr_list; cur != NULL; cur = cur->ai_next )
     {
         *fd = (int) socket( cur->ai_family, cur->ai_socktype,
                             cur->ai_protocol );
         if( *fd < 0 )
         {
             ret = POLARSSL_ERR_NET_SOCKET_FAILED;
             continue;
         }

         if( connect( *fd, cur->ai_addr, cur->ai_addrlen ) == 0 )
         {
             ret = 0;
             break;
         }

         close( *fd );
         ret = POLARSSL_ERR_NET_CONNECT_FAILED;
     }

     freeaddrinfo( addr_list );

     return( ret );

 #else
     /* Legacy IPv4-only version */

     int ret;
     struct sockaddr_in server_addr;
     struct hostent *server_host;

     if( ( ret = net_prepare() ) != 0 )
         return( ret );

     if( ( server_host = gethostbyname( host ) ) == NULL )
         return( POLARSSL_ERR_NET_UNKNOWN_HOST );

     if( ( *fd = (int) socket( AF_INET, SOCK_STREAM, IPPROTO_IP ) ) < 0 )
         return( POLARSSL_ERR_NET_SOCKET_FAILED );

     memcpy( (void *) &server_addr.sin_addr,
             (void *) server_host->h_addr,
                      server_host->h_length );

     server_addr.sin_family = AF_INET;
     server_addr.sin_port   = net_htons( port );

     if( connect( *fd, (struct sockaddr *) &server_addr,
                  sizeof( server_addr ) ) < 0 )
     {
         close( *fd );
         return( POLARSSL_ERR_NET_CONNECT_FAILED );
     }

     return( 0 );
 #endif /* POLARSSL_HAVE_IPV6 */
 }

 /*
  * Create a listening socket on bind_ip:port
  */
 int net_bind( int *fd, const char *bind_ip, int port )
 {
 #if defined(POLARSSL_HAVE_IPV6)
     int n, ret;
     struct addrinfo hints, *addr_list, *cur;
     char port_str[6];

     if( ( ret = net_prepare() ) != 0 )
         return( ret );

     /* getaddrinfo expects port as a string */
     memset( port_str, 0, sizeof( port_str ) );
     snprintf( port_str, sizeof( port_str ), "%d", port );

     /* Bind to IPv6 and/or IPv4, but only in TCP */
     memset( &hints, 0, sizeof( hints ) );
     hints.ai_family = AF_UNSPEC;
     hints.ai_socktype = SOCK_STREAM;
     hints.ai_protocol = IPPROTO_TCP;
     if( bind_ip == NULL )
         hints.ai_flags = AI_PASSIVE;

     if( getaddrinfo( bind_ip, port_str, &hints, &addr_list ) != 0 )
         return( POLARSSL_ERR_NET_UNKNOWN_HOST );

     /* Try the sockaddrs until a binding succeeds */
     ret = POLARSSL_ERR_NET_UNKNOWN_HOST;
     for( cur = addr_list; cur != NULL; cur = cur->ai_next )
     {
         *fd = (int) socket( cur->ai_family, cur->ai_socktype,
                             cur->ai_protocol );
         if( *fd < 0 )
         {
             ret = POLARSSL_ERR_NET_SOCKET_FAILED;
             continue;
         }

         n = 1;
         if( setsockopt( *fd, SOL_SOCKET, SO_REUSEADDR,
                         (const char *) &n, sizeof( n ) ) != 0 )
         {
             close( *fd );
             ret = POLARSSL_ERR_NET_SOCKET_FAILED;
             continue;
         }

         if( bind( *fd, cur->ai_addr, cur->ai_addrlen ) != 0 )
         {
             close( *fd );
             ret = POLARSSL_ERR_NET_BIND_FAILED;
             continue;
         }

         if( listen( *fd, POLARSSL_NET_LISTEN_BACKLOG ) != 0 )
         {
             close( *fd );
             ret = POLARSSL_ERR_NET_LISTEN_FAILED;
             continue;
         }

         /* I we ever get there, it's a success */
         ret = 0;
         break;
     }

     freeaddrinfo( addr_list );

     return( ret );

 #else
     /* Legacy IPv4-only version */

     int ret, n, c[4];
     struct sockaddr_in server_addr;

     if( ( ret = net_prepare() ) != 0 )
         return( ret );

     if( ( *fd = (int) socket( AF_INET, SOCK_STREAM, IPPROTO_IP ) ) < 0 )
         return( POLARSSL_ERR_NET_SOCKET_FAILED );

     n = 1;
     setsockopt( *fd, SOL_SOCKET, SO_REUSEADDR,
                 (const char *) &n, sizeof( n ) );

     server_addr.sin_addr.s_addr = net_htonl( INADDR_ANY );
     server_addr.sin_family      = AF_INET;
     server_addr.sin_port        = net_htons( port );

     if( bind_ip != NULL )
     {
         memset( c, 0, sizeof( c ) );
         sscanf( bind_ip, "%d.%d.%d.%d", &c[0], &c[1], &c[2], &c[3] );

         for( n = 0; n < 4; n++ )
             if( c[n] < 0 || c[n] > 255 )
                 break;

         if( n == 4 )
             server_addr.sin_addr.s_addr = net_htonl(
                 ( (uint32_t) c[0] << 24 ) |
                 ( (uint32_t) c[1] << 16 ) |
                 ( (uint32_t) c[2] <<  8 ) |
                 ( (uint32_t) c[3]       ) );
     }

     if( bind( *fd, (struct sockaddr *) &server_addr,
               sizeof( server_addr ) ) < 0 )
     {
         close( *fd );
         return( POLARSSL_ERR_NET_BIND_FAILED );
     }

     if( listen( *fd, POLARSSL_NET_LISTEN_BACKLOG ) != 0 )
     {
         close( *fd );
         return( POLARSSL_ERR_NET_LISTEN_FAILED );
     }

     return( 0 );
 #endif /* POLARSSL_HAVE_IPV6 */
 }

 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
 /*
  * Check if the requested operation would be blocking on a non-blocking socket
  * and thus 'failed' with a negative return value.
  */
 static int net_would_block( int fd )
 {
     ((void) fd);
     return( WSAGetLastError() == WSAEWOULDBLOCK );
 }
 #else
 /*
  * Check if the requested operation would be blocking on a non-blocking socket
  * and thus 'failed' with a negative return value.
  *
  * Note: on a blocking socket this function always returns 0!
  */
 static int net_would_block( int fd )
 {
     /*
      * Never return 'WOULD BLOCK' on a non-blocking socket
      */
     if( ( fcntl( fd, F_GETFL ) & O_NONBLOCK ) != O_NONBLOCK )
         return( 0 );

     switch( errno )
     {
 #if defined EAGAIN
         case EAGAIN:
 #endif
 #if defined EWOULDBLOCK && EWOULDBLOCK != EAGAIN
         case EWOULDBLOCK:
 #endif
             return( 1 );
     }
     return( 0 );
 }
 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */

 /*
  * Accept a connection from a remote client
  */
 int net_accept( int bind_fd, int *client_fd, void *client_ip )
 {
 #if defined(POLARSSL_HAVE_IPV6)
     struct sockaddr_storage client_addr;
 #else
     struct sockaddr_in client_addr;
 #endif

 #if defined(__socklen_t_defined) || defined(_SOCKLEN_T) ||  \
     defined(_SOCKLEN_T_DECLARED)
     socklen_t n = (socklen_t) sizeof( client_addr );
 #else
     int n = (int) sizeof( client_addr );
 #endif

     *client_fd = (int) accept( bind_fd, (struct sockaddr *)
                                &client_addr, &n );

     if( *client_fd < 0 )
     {
         if( net_would_block( *client_fd ) != 0 )
             return( POLARSSL_ERR_NET_WANT_READ );

         return( POLARSSL_ERR_NET_ACCEPT_FAILED );
     }

     if( client_ip != NULL )
     {
 #if defined(POLARSSL_HAVE_IPV6)
         if( client_addr.ss_family == AF_INET )
         {
             struct sockaddr_in *addr4 = (struct sockaddr_in *) &client_addr;
             memcpy( client_ip, &addr4->sin_addr.s_addr,
                         sizeof( addr4->sin_addr.s_addr ) );
         }
         else
         {
             struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *) &client_addr;
             memcpy( client_ip, &addr6->sin6_addr.s6_addr,
                         sizeof( addr6->sin6_addr.s6_addr ) );
         }
 #else
         memcpy( client_ip, &client_addr.sin_addr.s_addr,
                     sizeof( client_addr.sin_addr.s_addr ) );
 #endif /* POLARSSL_HAVE_IPV6 */
     }

     return( 0 );
 }

 /*
  * Set the socket blocking or non-blocking
  */
 int net_set_block( int fd )
 {
 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
     u_long n = 0;
     return( ioctlsocket( fd, FIONBIO, &n ) );
 #else
     return( fcntl( fd, F_SETFL, fcntl( fd, F_GETFL ) & ~O_NONBLOCK ) );
 #endif
 }

 int net_set_nonblock( int fd )
 {
 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
     u_long n = 1;
     return( ioctlsocket( fd, FIONBIO, &n ) );
 #else
     return( fcntl( fd, F_SETFL, fcntl( fd, F_GETFL ) | O_NONBLOCK ) );
 #endif
 }

 #if defined(POLARSSL_HAVE_TIME)
 /*
  * Portable usleep helper
  */
 void net_usleep( unsigned long usec )
 {
     struct timeval tv;
     tv.tv_sec  = 0;
     tv.tv_usec = usec;
     select( 0, NULL, NULL, NULL, &tv );
 }
 #endif /* POLARSSL_HAVE_TIME */

 /*
  * Read at most 'len' characters
  */
 int net_recv( void *ctx, unsigned char *buf, size_t len )
 {
     int fd = *((int *) ctx);
     int ret = read( fd, buf, len );

     if( ret < 0 )
     {
         if( net_would_block( fd ) != 0 )
             return( POLARSSL_ERR_NET_WANT_READ );

 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
         if( WSAGetLastError() == WSAECONNRESET )
             return( POLARSSL_ERR_NET_CONN_RESET );
 #else
         if( errno == EPIPE || errno == ECONNRESET )
             return( POLARSSL_ERR_NET_CONN_RESET );

         if( errno == EINTR )
             return( POLARSSL_ERR_NET_WANT_READ );
 #endif

         return( POLARSSL_ERR_NET_RECV_FAILED );
     }

     return( ret );
 }

 /*
  * Write at most 'len' characters
  */
 int net_send( void *ctx, const unsigned char *buf, size_t len )
 {
     int fd = *((int *) ctx);
     int ret = write( fd, buf, len );

     if( ret < 0 )
     {
         if( net_would_block( fd ) != 0 )
             return( POLARSSL_ERR_NET_WANT_WRITE );

 #if ( defined(_WIN32) || defined(_WIN32_WCE) ) && !defined(EFIX64) && \
     !defined(EFI32)
         if( WSAGetLastError() == WSAECONNRESET )
             return( POLARSSL_ERR_NET_CONN_RESET );
 #else
         if( errno == EPIPE || errno == ECONNRESET )
             return( POLARSSL_ERR_NET_CONN_RESET );

         if( errno == EINTR )
             return( POLARSSL_ERR_NET_WANT_WRITE );
 #endif

         return( POLARSSL_ERR_NET_SEND_FAILED );
     }

     return( ret );
 }

 /*
  * Gracefully close the connection
  */
 void net_close( int fd )
 {
     shutdown( fd, 2 );
     close( fd );
 }

 #endif /* POLARSSL_NET_C */
	/*
	* TCP networking functions
	*
	* Copyright (C) 2006-2014, Brainspark B.V.
	*
	* This file is part of PolarSSL (http://www.polarssl.org)
	* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
	*
	* All rights reserved.
	*
	* 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.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	#if !defined(POLARSSL_CONFIG_FILE)
	#include "polarssl/config.h"
	#else
	#include POLARSSL_CONFIG_FILE
	#endif

	#if defined(POLARSSL_NET_C)

	#include "polarssl/net.h"

	#if (defined(_WIN32) \|\| defined(_WIN32_WCE)) && !defined(EFIX64) && \
	!defined(EFI32)

	#if defined(POLARSSL_HAVE_IPV6)
	#ifdef _WIN32_WINNT
	#undef _WIN32_WINNT
	#endif
	/* Enables getaddrinfo() & Co */
	#define _WIN32_WINNT 0x0501
	#include <ws2tcpip.h>
	#endif

	#include <winsock2.h>
	#include <windows.h>

	#if defined(_MSC_VER)
	#if defined(_WIN32_WCE)
	#pragma comment( lib, "ws2.lib" )
	#else
	#pragma comment( lib, "ws2_32.lib" )
	#endif
	#endif /* _MSC_VER */

	#define read(fd,buf,len) recv(fd,(char*)buf,(int) len,0)
	#define write(fd,buf,len) send(fd,(char*)buf,(int) len,0)
	#define close(fd) closesocket(fd)

	static int wsa_init_done = 0;

	#else /* ( _WIN32 \|\| _WIN32_WCE ) && !EFIX64 && !EFI32 */

	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#if defined(POLARSSL_HAVE_TIME)
	#include <sys/time.h>
	#endif
	#include <unistd.h>
	#include <signal.h>
	#include <fcntl.h>
	#include <netdb.h>
	#include <errno.h>

	#if defined(__FreeBSD__) \|\| defined(__OpenBSD__) \|\| defined(__NetBSD__) \|\| \
	defined(__DragonFly__)
	#include <sys/endian.h>
	#elif defined(__APPLE__) \|\| defined(HAVE_MACHINE_ENDIAN_H) \|\| \
	defined(EFIX64) \|\| defined(EFI32)
	#include <machine/endian.h>
	#elif defined(sun)
	#include <sys/isa_defs.h>
	#elif defined(_AIX) \|\| defined(HAVE_ARPA_NAMESER_COMPAT_H)
	#include <arpa/nameser_compat.h>
	#else
	#include <endian.h>
	#endif

	#endif /* ( _WIN32 \|\| _WIN32_WCE ) && !EFIX64 && !EFI32 */

	#include <stdlib.h>
	#include <stdio.h>

	#if defined(_MSC_VER) && !defined snprintf && !defined(EFIX64) && \
	!defined(EFI32)
	#define snprintf _snprintf
	#endif

	#if defined(POLARSSL_HAVE_TIME)
	#include <time.h>
	#endif

	#if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
	#include <basetsd.h>
	typedef UINT32 uint32_t;
	#else
	#include <inttypes.h>
	#endif

	/*
	* htons() is not always available.
	* By default go for LITTLE_ENDIAN variant. Otherwise hope for _BYTE_ORDER and
	* __BIG_ENDIAN to help determine endianness.
	*/
	#if defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \
	__BYTE_ORDER == __BIG_ENDIAN
	#define POLARSSL_HTONS(n) (n)
	#define POLARSSL_HTONL(n) (n)
	#else
	#define POLARSSL_HTONS(n) ((((unsigned short)(n) & 0xFF ) << 8 ) \| \
	(((unsigned short)(n) & 0xFF00 ) >> 8 ))
	#define POLARSSL_HTONL(n) ((((unsigned long )(n) & 0xFF ) << 24) \| \
	(((unsigned long )(n) & 0xFF00 ) << 8 ) \| \
	(((unsigned long )(n) & 0xFF0000 ) >> 8 ) \| \
	(((unsigned long )(n) & 0xFF000000) >> 24))
	#endif

	unsigned short net_htons( unsigned short n );
	unsigned long net_htonl( unsigned long n );
	#define net_htons(n) POLARSSL_HTONS(n)
	#define net_htonl(n) POLARSSL_HTONL(n)

	/*
	* Prepare for using the sockets interface
	*/
	static int net_prepare( void )
	{
	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	WSADATA wsaData;

	if( wsa_init_done == 0 )
	{
	if( WSAStartup( MAKEWORD(2,0), &wsaData ) != 0 )
	return( POLARSSL_ERR_NET_SOCKET_FAILED );

	wsa_init_done = 1;
	}
	#else
	#if !defined(EFIX64) && !defined(EFI32)
	signal( SIGPIPE, SIG_IGN );
	#endif
	#endif
	return( 0 );
	}

	/*
	* Initiate a TCP connection with host:port
	*/
	int net_connect( int fd, const char host, int port )
	{
	#if defined(POLARSSL_HAVE_IPV6)
	int ret;
	struct addrinfo hints, addr_list, cur;
	char port_str[6];

	if( ( ret = net_prepare() ) != 0 )
	return( ret );

	/* getaddrinfo expects port as a string */
	memset( port_str, 0, sizeof( port_str ) );
	snprintf( port_str, sizeof( port_str ), "%d", port );

	/* Do name resolution with both IPv6 and IPv4, but only TCP */
	memset( &hints, 0, sizeof( hints ) );
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;

	if( getaddrinfo( host, port_str, &hints, &addr_list ) != 0 )
	return( POLARSSL_ERR_NET_UNKNOWN_HOST );

	/* Try the sockaddrs until a connection succeeds */
	ret = POLARSSL_ERR_NET_UNKNOWN_HOST;
	for( cur = addr_list; cur != NULL; cur = cur->ai_next )
	{
	*fd = (int) socket( cur->ai_family, cur->ai_socktype,
	cur->ai_protocol );
	if( *fd < 0 )
	{
	ret = POLARSSL_ERR_NET_SOCKET_FAILED;
	continue;
	}

	if( connect( *fd, cur->ai_addr, cur->ai_addrlen ) == 0 )
	{
	ret = 0;
	break;
	}

	close( *fd );
	ret = POLARSSL_ERR_NET_CONNECT_FAILED;
	}

	freeaddrinfo( addr_list );

	return( ret );

	#else
	/* Legacy IPv4-only version */

	int ret;
	struct sockaddr_in server_addr;
	struct hostent *server_host;

	if( ( ret = net_prepare() ) != 0 )
	return( ret );

	if( ( server_host = gethostbyname( host ) ) == NULL )
	return( POLARSSL_ERR_NET_UNKNOWN_HOST );

	if( ( *fd = (int) socket( AF_INET, SOCK_STREAM, IPPROTO_IP ) ) < 0 )
	return( POLARSSL_ERR_NET_SOCKET_FAILED );

	memcpy( (void *) &server_addr.sin_addr,
	(void *) server_host->h_addr,
	server_host->h_length );

	server_addr.sin_family = AF_INET;
	server_addr.sin_port = net_htons( port );

	if( connect( fd, (struct sockaddr ) &server_addr,
	sizeof( server_addr ) ) < 0 )
	{
	close( *fd );
	return( POLARSSL_ERR_NET_CONNECT_FAILED );
	}

	return( 0 );
	#endif /* POLARSSL_HAVE_IPV6 */
	}

	/*
	* Create a listening socket on bind_ip:port
	*/
	int net_bind( int fd, const char bind_ip, int port )
	{
	#if defined(POLARSSL_HAVE_IPV6)
	int n, ret;
	struct addrinfo hints, addr_list, cur;
	char port_str[6];

	if( ( ret = net_prepare() ) != 0 )
	return( ret );

	/* getaddrinfo expects port as a string */
	memset( port_str, 0, sizeof( port_str ) );
	snprintf( port_str, sizeof( port_str ), "%d", port );

	/* Bind to IPv6 and/or IPv4, but only in TCP */
	memset( &hints, 0, sizeof( hints ) );
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	if( bind_ip == NULL )
	hints.ai_flags = AI_PASSIVE;

	if( getaddrinfo( bind_ip, port_str, &hints, &addr_list ) != 0 )
	return( POLARSSL_ERR_NET_UNKNOWN_HOST );

	/* Try the sockaddrs until a binding succeeds */
	ret = POLARSSL_ERR_NET_UNKNOWN_HOST;
	for( cur = addr_list; cur != NULL; cur = cur->ai_next )
	{
	*fd = (int) socket( cur->ai_family, cur->ai_socktype,
	cur->ai_protocol );
	if( *fd < 0 )
	{
	ret = POLARSSL_ERR_NET_SOCKET_FAILED;
	continue;
	}

	n = 1;
	if( setsockopt( *fd, SOL_SOCKET, SO_REUSEADDR,
	(const char *) &n, sizeof( n ) ) != 0 )
	{
	close( *fd );
	ret = POLARSSL_ERR_NET_SOCKET_FAILED;
	continue;
	}

	if( bind( *fd, cur->ai_addr, cur->ai_addrlen ) != 0 )
	{
	close( *fd );
	ret = POLARSSL_ERR_NET_BIND_FAILED;
	continue;
	}

	if( listen( *fd, POLARSSL_NET_LISTEN_BACKLOG ) != 0 )
	{
	close( *fd );
	ret = POLARSSL_ERR_NET_LISTEN_FAILED;
	continue;
	}

	/* I we ever get there, it's a success */
	ret = 0;
	break;
	}

	freeaddrinfo( addr_list );

	return( ret );

	#else
	/* Legacy IPv4-only version */

	int ret, n, c[4];
	struct sockaddr_in server_addr;

	if( ( ret = net_prepare() ) != 0 )
	return( ret );

	if( ( *fd = (int) socket( AF_INET, SOCK_STREAM, IPPROTO_IP ) ) < 0 )
	return( POLARSSL_ERR_NET_SOCKET_FAILED );

	n = 1;
	setsockopt( *fd, SOL_SOCKET, SO_REUSEADDR,
	(const char *) &n, sizeof( n ) );

	server_addr.sin_addr.s_addr = net_htonl( INADDR_ANY );
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = net_htons( port );

	if( bind_ip != NULL )
	{
	memset( c, 0, sizeof( c ) );
	sscanf( bind_ip, "%d.%d.%d.%d", &c[0], &c[1], &c[2], &c[3] );

	for( n = 0; n < 4; n++ )
	if( c[n] < 0 \|\| c[n] > 255 )
	break;

	if( n == 4 )
	server_addr.sin_addr.s_addr = net_htonl(
	( (uint32_t) c[0] << 24 ) \|
	( (uint32_t) c[1] << 16 ) \|
	( (uint32_t) c[2] << 8 ) \|
	( (uint32_t) c[3] ) );
	}

	if( bind( fd, (struct sockaddr ) &server_addr,
	sizeof( server_addr ) ) < 0 )
	{
	close( *fd );
	return( POLARSSL_ERR_NET_BIND_FAILED );
	}

	if( listen( *fd, POLARSSL_NET_LISTEN_BACKLOG ) != 0 )
	{
	close( *fd );
	return( POLARSSL_ERR_NET_LISTEN_FAILED );
	}

	return( 0 );
	#endif /* POLARSSL_HAVE_IPV6 */
	}

	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	/*
	* Check if the requested operation would be blocking on a non-blocking socket
	* and thus 'failed' with a negative return value.
	*/
	static int net_would_block( int fd )
	{
	((void) fd);
	return( WSAGetLastError() == WSAEWOULDBLOCK );
	}
	#else
	/*
	* Check if the requested operation would be blocking on a non-blocking socket
	* and thus 'failed' with a negative return value.
	*
	* Note: on a blocking socket this function always returns 0!
	*/
	static int net_would_block( int fd )
	{
	/*
	* Never return 'WOULD BLOCK' on a non-blocking socket
	*/
	if( ( fcntl( fd, F_GETFL ) & O_NONBLOCK ) != O_NONBLOCK )
	return( 0 );

	switch( errno )
	{
	#if defined EAGAIN
	case EAGAIN:
	#endif
	#if defined EWOULDBLOCK && EWOULDBLOCK != EAGAIN
	case EWOULDBLOCK:
	#endif
	return( 1 );
	}
	return( 0 );
	}
	#endif /* ( _WIN32 \|\| _WIN32_WCE ) && !EFIX64 && !EFI32 */

	/*
	* Accept a connection from a remote client
	*/
	int net_accept( int bind_fd, int client_fd, void client_ip )
	{
	#if defined(POLARSSL_HAVE_IPV6)
	struct sockaddr_storage client_addr;
	#else
	struct sockaddr_in client_addr;
	#endif

	#if defined(__socklen_t_defined) \|\| defined(_SOCKLEN_T) \|\| \
	defined(_SOCKLEN_T_DECLARED)
	socklen_t n = (socklen_t) sizeof( client_addr );
	#else
	int n = (int) sizeof( client_addr );
	#endif

	client_fd = (int) accept( bind_fd, (struct sockaddr )
	&client_addr, &n );

	if( *client_fd < 0 )
	{
	if( net_would_block( *client_fd ) != 0 )
	return( POLARSSL_ERR_NET_WANT_READ );

	return( POLARSSL_ERR_NET_ACCEPT_FAILED );
	}

	if( client_ip != NULL )
	{
	#if defined(POLARSSL_HAVE_IPV6)
	if( client_addr.ss_family == AF_INET )
	{
	struct sockaddr_in addr4 = (struct sockaddr_in ) &client_addr;
	memcpy( client_ip, &addr4->sin_addr.s_addr,
	sizeof( addr4->sin_addr.s_addr ) );
	}
	else
	{
	struct sockaddr_in6 addr6 = (struct sockaddr_in6 ) &client_addr;
	memcpy( client_ip, &addr6->sin6_addr.s6_addr,
	sizeof( addr6->sin6_addr.s6_addr ) );
	}
	#else
	memcpy( client_ip, &client_addr.sin_addr.s_addr,
	sizeof( client_addr.sin_addr.s_addr ) );
	#endif /* POLARSSL_HAVE_IPV6 */
	}

	return( 0 );
	}

	/*
	* Set the socket blocking or non-blocking
	*/
	int net_set_block( int fd )
	{
	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	u_long n = 0;
	return( ioctlsocket( fd, FIONBIO, &n ) );
	#else
	return( fcntl( fd, F_SETFL, fcntl( fd, F_GETFL ) & ~O_NONBLOCK ) );
	#endif
	}

	int net_set_nonblock( int fd )
	{
	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	u_long n = 1;
	return( ioctlsocket( fd, FIONBIO, &n ) );
	#else
	return( fcntl( fd, F_SETFL, fcntl( fd, F_GETFL ) \| O_NONBLOCK ) );
	#endif
	}

	#if defined(POLARSSL_HAVE_TIME)
	/*
	* Portable usleep helper
	*/
	void net_usleep( unsigned long usec )
	{
	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = usec;
	select( 0, NULL, NULL, NULL, &tv );
	}
	#endif /* POLARSSL_HAVE_TIME */

	/*
	* Read at most 'len' characters
	*/
	int net_recv( void ctx, unsigned char buf, size_t len )
	{
	int fd = ((int ) ctx);
	int ret = read( fd, buf, len );

	if( ret < 0 )
	{
	if( net_would_block( fd ) != 0 )
	return( POLARSSL_ERR_NET_WANT_READ );

	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	if( WSAGetLastError() == WSAECONNRESET )
	return( POLARSSL_ERR_NET_CONN_RESET );
	#else
	if( errno == EPIPE \|\| errno == ECONNRESET )
	return( POLARSSL_ERR_NET_CONN_RESET );

	if( errno == EINTR )
	return( POLARSSL_ERR_NET_WANT_READ );
	#endif

	return( POLARSSL_ERR_NET_RECV_FAILED );
	}

	return( ret );
	}

	/*
	* Write at most 'len' characters
	*/
	int net_send( void ctx, const unsigned char buf, size_t len )
	{
	int fd = ((int ) ctx);
	int ret = write( fd, buf, len );

	if( ret < 0 )
	{
	if( net_would_block( fd ) != 0 )
	return( POLARSSL_ERR_NET_WANT_WRITE );

	#if ( defined(_WIN32) \|\| defined(_WIN32_WCE) ) && !defined(EFIX64) && \
	!defined(EFI32)
	if( WSAGetLastError() == WSAECONNRESET )
	return( POLARSSL_ERR_NET_CONN_RESET );
	#else
	if( errno == EPIPE \|\| errno == ECONNRESET )
	return( POLARSSL_ERR_NET_CONN_RESET );

	if( errno == EINTR )
	return( POLARSSL_ERR_NET_WANT_WRITE );
	#endif

	return( POLARSSL_ERR_NET_SEND_FAILED );
	}

	return( ret );
	}

	/*
	* Gracefully close the connection
	*/
	void net_close( int fd )
	{
	shutdown( fd, 2 );
	close( fd );
	}

	#endif /* POLARSSL_NET_C */