programs/test/udp_proxy.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  UDP proxy: emulate an unreliable UDP connexion for DTLS testing
  *
  *  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 <stdio.h>
 int main( void )
 {
     printf( "POLARSSL_NET_C not defined.\n" );
     return( 0 );
 }
 #else

 #include "polarssl/net.h"
 #include "polarssl/error.h"
 #include "polarssl/ssl.h"

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

 /* For select() */
 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
     !defined(EFI32)
 #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 */
 #else /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */

 /* For gettimeofday() */
 #if !defined(_WIN32)
 #include <sys/time.h>
 #endif

 #define MAX_MSG_SIZE            16384 + 2048 /* max record/datagram size */

 #define DFL_SERVER_ADDR         "localhost"
 #define DFL_SERVER_PORT         4433
 #define DFL_LISTEN_ADDR         "localhost"
 #define DFL_LISTEN_PORT         5556

 #define USAGE                                                               \
     "\n usage: udp_proxy param=<>...\n"                                     \
     "\n acceptable parameters:\n"                                           \
     "    server_addr=%%d      default: localhost\n"                         \
     "    server_port=%%d      default: 4433\n"                              \
     "    listen_addr=%%d      default: localhost\n"                         \
     "    listen_port=%%d      default: 4433\n"                              \
     "\n"                                                                    \
     "    duplicate=%%d        default: 0 (no duplication)\n"                \
     "                        duplicate about 1:N packets randomly\n"        \
     "    delay=%%d            default: 0 (no delayed packets)\n"            \
     "                        delay about 1:N packets randomly\n"            \
     "    delay_ccs=%%d        default: 0 (don't delay ChangeCipherSpec)\n" \
     "    drop=%%d             default: 0 (no dropped packets)\n"            \
     "                        drop about 1:N packets randomly\n"             \
     "    mtu=%%d              default: 0 (unlimited)\n"                     \
     "                        drop packets larger than N bytes\n"            \
     "    bad_ad=%%d           default: 0 (don't add bad ApplicationData)\n" \
     "\n"                                                                    \
     "    seed=%%d             default: (use current time)\n"                \
     "\n"

 /*
  * global options
  */
 static struct options
 {
     const char *server_addr;    /* address to forward packets to            */
     int server_port;            /* port to forward packets to               */
     const char *listen_addr;    /* address for accepting client connections */
     int listen_port;            /* port for accepting client connections    */

     int duplicate;              /* duplicate 1 in N packets (none if 0)     */
     int delay;                  /* delay 1 packet in N (none if 0)          */
     int delay_ccs;              /* delay ChangeCipherSpec                   */
     int drop;                   /* drop 1 packet in N (none if 0)           */
     int mtu;                    /* drop packets larger than this            */
     int bad_ad;                 /* inject corrupted ApplicationData record  */

     unsigned int seed;          /* seed for "random" events                 */
 } opt;

 static void exit_usage( const char *name, const char *value )
 {
     if( value == NULL )
         printf( " unknown option or missing value: %s\n", name );
     else
         printf( " option %s: illegal value: %s\n", name, value );

     printf( USAGE );
     exit( 1 );
 }

 static void get_options( int argc, char *argv[] )
 {
     int i;
     char *p, *q;

     opt.server_addr    = DFL_SERVER_ADDR;
     opt.server_port    = DFL_SERVER_PORT;
     opt.listen_addr    = DFL_LISTEN_ADDR;
     opt.listen_port    = DFL_LISTEN_PORT;
     /* Other members default to 0 */

     for( i = 1; i < argc; i++ )
     {
         p = argv[i];
         if( ( q = strchr( p, '=' ) ) == NULL )
             exit_usage( p, NULL );
         *q++ = '\0';

         if( strcmp( p, "server_addr" ) == 0 )
             opt.server_addr = q;
         else if( strcmp( p, "server_port" ) == 0 )
         {
             opt.server_port = atoi( q );
             if( opt.server_port < 1 || opt.server_port > 65535 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "listen_addr" ) == 0 )
             opt.listen_addr = q;
         else if( strcmp( p, "listen_port" ) == 0 )
         {
             opt.listen_port = atoi( q );
             if( opt.listen_port < 1 || opt.listen_port > 65535 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "duplicate" ) == 0 )
         {
             opt.duplicate = atoi( q );
             if( opt.duplicate < 0 || opt.duplicate > 20 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "delay" ) == 0 )
         {
             opt.delay = atoi( q );
             if( opt.delay < 0 || opt.delay > 20 || opt.delay == 1 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "delay_ccs" ) == 0 )
         {
             opt.delay_ccs = atoi( q );
             if( opt.delay_ccs < 0 || opt.delay_ccs > 1 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "drop" ) == 0 )
         {
             opt.drop = atoi( q );
             if( opt.drop < 0 || opt.drop > 20 || opt.drop == 1 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "mtu" ) == 0 )
         {
             opt.mtu = atoi( q );
             if( opt.mtu < 0 || opt.mtu > MAX_MSG_SIZE )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "bad_ad" ) == 0 )
         {
             opt.bad_ad = atoi( q );
             if( opt.bad_ad < 0 || opt.bad_ad > 1 )
                 exit_usage( p, q );
         }
         else if( strcmp( p, "seed" ) == 0 )
         {
             opt.seed = atoi( q );
             if( opt.seed == 0 )
                 exit_usage( p, q );
         }
         else
             exit_usage( p, NULL );
     }
 }

 static const char *msg_type( unsigned char *msg, size_t len )
 {
     if( len < 1 )                           return( "Invalid" );
     switch( msg[0] )
     {
         case SSL_MSG_CHANGE_CIPHER_SPEC:    return( "ChangeCipherSpec" );
         case SSL_MSG_ALERT:                 return( "Alert" );
         case SSL_MSG_APPLICATION_DATA:      return( "ApplicationData" );
         case SSL_MSG_HANDSHAKE:             break; /* See below */
         default:                            return( "Unknown" );
     }

     if( len < 13 + 12 )                     return( "Invalid handshake" );

     /*
      * Our handshake message are less than 2^16 bytes long, so they should
      * have 0 as the first byte of length, frag_offset and frag_length.
      * Otherwise, assume they are encrypted.
      */
     if( msg[14] || msg[19] || msg[22] )     return( "Encrypted handshake" );

     switch( msg[13] )
     {
         case SSL_HS_HELLO_REQUEST:          return( "HelloRequest" );
         case SSL_HS_CLIENT_HELLO:           return( "ClientHello" );
         case SSL_HS_SERVER_HELLO:           return( "ServerHello" );
         case SSL_HS_HELLO_VERIFY_REQUEST:   return( "HelloVerifyRequest" );
         case SSL_HS_NEW_SESSION_TICKET:     return( "NewSessionTicket" );
         case SSL_HS_CERTIFICATE:            return( "Certificate" );
         case SSL_HS_SERVER_KEY_EXCHANGE:    return( "ServerKeyExchange" );
         case SSL_HS_CERTIFICATE_REQUEST:    return( "CertificateRequest" );
         case SSL_HS_SERVER_HELLO_DONE:      return( "ServerHelloDone" );
         case SSL_HS_CERTIFICATE_VERIFY:     return( "CertificateVerify" );
         case SSL_HS_CLIENT_KEY_EXCHANGE:    return( "ClientKeyExchange" );
         case SSL_HS_FINISHED:               return( "Finished" );
         default:                            return( "Unknown handshake" );
     }
 }

 /* Return elapsed time in milliseconds since the first call */
 static unsigned long ellapsed_time( void )
 {
 #if defined(_WIN32)
     return( 0 );
 #else
     static struct timeval ref = { 0, 0 };
     struct timeval now;

     if( ref.tv_sec == 0 && ref.tv_usec == 0 )
     {
         gettimeofday( &ref, NULL );
         return( 0 );
     }

     gettimeofday( &now, NULL );
     return( 1000 * ( now.tv_sec  - ref.tv_sec )
                  + ( now.tv_usec - ref.tv_usec ) / 1000 );
 #endif
 }

 typedef struct
 {
     int dst;
     const char *way;
     const char *type;
     unsigned len;
     unsigned char buf[MAX_MSG_SIZE];
 } packet;

 /* Print packet. Outgoing packets come with a reason (forward, dupl, etc.) */
 void print_packet( const packet *p, const char *why )
 {
     if( why == NULL )
         printf( "  %05lu %s %s (%u bytes)\n",
                 ellapsed_time(), p->way, p->type, p->len );
     else
         printf( "        %s %s (%u bytes): %s\n",
                 p->way, p->type, p->len, why );
     fflush( stdout );
 }

 int send_packet( const packet *p, const char *why )
 {
     int ret;
     int dst = p->dst;

     /* insert corrupted ApplicationData record? */
     if( opt.bad_ad &&
         strcmp( p->type, "ApplicationData" ) == 0 )
     {
         unsigned char buf[MAX_MSG_SIZE];
         memcpy( buf, p->buf, p->len );
         ++buf[p->len - 1];

         print_packet( p, "corrupted" );
         if( ( ret = net_send( &dst, buf, p->len ) ) <= 0 )
         {
             printf( "  ! net_send returned %d\n", ret );
             return( ret );
         }
     }

     print_packet( p, why );
     if( ( ret = net_send( &dst, p->buf, p->len ) ) <= 0 )
     {
         printf( "  ! net_send returned %d\n", ret );
         return( ret );
     }

     /* Don't duplicate Application Data, only handshake covered */
     if( opt.duplicate != 0 &&
         strcmp( p->type, "ApplicationData" ) != 0 &&
         rand() % opt.duplicate == 0 )
     {
         print_packet( p, "duplicated" );

         if( ( ret = net_send( &dst, p->buf, p->len ) ) <= 0 )
         {
             printf( "  ! net_send returned %d\n", ret );
             return( ret );
         }
     }

     return( 0 );
 }

 static packet prev;

 void clear_pending( void )
 {
     memset( &prev, 0, sizeof( packet ) );
 }

 int handle_message( const char *way, int dst, int src )
 {
     int ret;
     packet cur;

     /* receive packet */
     if( ( ret = net_recv( &src, cur.buf, sizeof( cur.buf ) ) ) <= 0 )
     {
         printf( "  ! net_recv returned %d\n", ret );
         return( ret );
     }

     cur.len  = ret;
     cur.type = msg_type( cur.buf, cur.len );
     cur.way  = way;
     cur.dst  = dst;
     print_packet( &cur, NULL );

     /* do we want to drop, delay, or forward it? */
     if( ( opt.mtu != 0 &&
           cur.len > (unsigned) opt.mtu ) ||
         ( opt.drop != 0 &&
           strcmp( cur.type, "ApplicationData" ) != 0 &&
           rand() % opt.drop == 0 ) )
     {
         ; /* Nothing to do */
     }
     else if( ( opt.delay_ccs == 1 &&
                strcmp( cur.type, "ChangeCipherSpec" ) == 0 ) ||
              ( opt.delay != 0 &&
                strcmp( cur.type, "ApplicationData" ) != 0 &&
                prev.dst == 0 &&
                rand() % opt.delay == 0 ) )
     {
         memcpy( &prev, &cur, sizeof( packet ) );
     }
     else
     {
         /* forward and possibly duplicate */
         if( ( ret = send_packet( &cur, "forwarded" ) ) != 0 )
             return( ret );

         /* send previously delayed message if any */
         if( prev.dst != 0 )
         {
             ret = send_packet( &prev, "delayed" );
             memset( &prev, 0, sizeof( packet ) );
             if( ret != 0 )
                 return( ret );
         }
     }

     return( 0 );
 }

 int main( int argc, char *argv[] )
 {
     int ret;

     int listen_fd = -1;
     int client_fd = -1;
     int server_fd = -1;

     int nb_fds;
     fd_set read_fds;

     get_options( argc, argv );

     /*
      * Decisions to drop/delay/duplicate packets are pseudo-random: dropping
      * exactly 1 in N packets would lead to problems when a flight has exactly
      * N packets: the same packet would be dropped on every resend.
      *
      * In order to be able to reproduce problems reliably, the seed may be
      * specified explicitly.
      */
     if( opt.seed == 0 )
     {
         opt.seed = time( NULL );
         printf( "  . Pseudo-random seed: %u\n", opt.seed );
     }

     srand( opt.seed );

     /*
      * 0. "Connect" to the server
      */
     printf( "  . Connect to server on UDP/%s/%d ...",
             opt.server_addr, opt.server_port );
     fflush( stdout );

     if( ( ret = net_connect( &server_fd, opt.server_addr, opt.server_port,
                              NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! net_connect returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 1. Setup the "listening" UDP socket
      */
     printf( "  . Bind on UDP/%s/%d ...",
             opt.listen_addr, opt.listen_port );
     fflush( stdout );

     if( ( ret = net_bind( &listen_fd, opt.listen_addr, opt.listen_port,
                           NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! net_bind returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 2. Wait until a client connects
      */
 accept:
     printf( "  . Waiting for a remote connection ..." );
     fflush( stdout );

     if( ( ret = net_accept( listen_fd, &client_fd, NULL ) ) != 0 )
     {
         printf( " failed\n  ! net_accept returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );
     fflush( stdout );

     printf( "  . Re-bind on UDP/%s/%d ...",
             opt.listen_addr, opt.listen_port );
     fflush( stdout );

     if( ( ret = net_bind( &listen_fd, opt.listen_addr, opt.listen_port,
                           NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! net_bind returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 3. Forward packets forever (kill the process to terminate it)
      */
     nb_fds = client_fd;
     if( nb_fds < server_fd )
         nb_fds = server_fd;
     if( nb_fds < listen_fd )
         nb_fds = listen_fd;
     ++nb_fds;

     while( 1 )
     {
         FD_ZERO( &read_fds );
         FD_SET( server_fd, &read_fds );
         FD_SET( client_fd, &read_fds );
         FD_SET( listen_fd, &read_fds );

         if( ( ret = select( nb_fds, &read_fds, NULL, NULL, NULL ) ) <= 0 )
         {
             perror( "select" );
             goto exit;
         }

         if( FD_ISSET( listen_fd, &read_fds ) )
         {
             clear_pending();
             goto accept;
         }

         if( FD_ISSET( client_fd, &read_fds ) )
         {
             if( ( ret = handle_message( "S <- C",
                                         server_fd, client_fd ) ) != 0 )
                 goto exit;
         }

         if( FD_ISSET( server_fd, &read_fds ) )
         {
             if( ( ret = handle_message( "S -> C",
                                         client_fd, server_fd ) ) != 0 )
                 goto exit;
         }
     }

 exit:

 #ifdef POLARSSL_ERROR_C
     if( ret != 0 )
     {
         char error_buf[100];
         polarssl_strerror( ret, error_buf, 100 );
         printf( "Last error was: -0x%04X - %s\n\n", - ret, error_buf );
         fflush( stdout );
     }
 #endif

     if( client_fd != -1 )
         net_close( client_fd );

     if( listen_fd != -1 )
         net_close( listen_fd );

 #if defined(_WIN32)
     printf( "  Press Enter to exit this program.\n" );
     fflush( stdout ); getchar();
 #endif

     return( ret != 0 );
 }

 #endif /* POLARSSL_NET_C */
	/*
	* UDP proxy: emulate an unreliable UDP connexion for DTLS testing
	*
	* 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 <stdio.h>
	int main( void )
	{
	printf( "POLARSSL_NET_C not defined.\n" );
	return( 0 );
	}
	#else

	#include "polarssl/net.h"
	#include "polarssl/error.h"
	#include "polarssl/ssl.h"

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

	/* For select() */
	#if (defined(_WIN32) \|\| defined(_WIN32_WCE)) && !defined(EFIX64) && \
	!defined(EFI32)
	#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 */
	#else /* ( _WIN32 \|\| _WIN32_WCE ) && !EFIX64 && !EFI32 */
	#include <sys/time.h>
	#include <sys/types.h>
	#include <unistd.h>
	#endif /* ( _WIN32 \|\| _WIN32_WCE ) && !EFIX64 && !EFI32 */

	/* For gettimeofday() */
	#if !defined(_WIN32)
	#include <sys/time.h>
	#endif

	#define MAX_MSG_SIZE 16384 + 2048 /* max record/datagram size */

	#define DFL_SERVER_ADDR "localhost"
	#define DFL_SERVER_PORT 4433
	#define DFL_LISTEN_ADDR "localhost"
	#define DFL_LISTEN_PORT 5556

	#define USAGE \
	"\n usage: udp_proxy param=<>...\n" \
	"\n acceptable parameters:\n" \
	" server_addr=%%d default: localhost\n" \
	" server_port=%%d default: 4433\n" \
	" listen_addr=%%d default: localhost\n" \
	" listen_port=%%d default: 4433\n" \
	"\n" \
	" duplicate=%%d default: 0 (no duplication)\n" \
	" duplicate about 1:N packets randomly\n" \
	" delay=%%d default: 0 (no delayed packets)\n" \
	" delay about 1:N packets randomly\n" \
	" delay_ccs=%%d default: 0 (don't delay ChangeCipherSpec)\n" \
	" drop=%%d default: 0 (no dropped packets)\n" \
	" drop about 1:N packets randomly\n" \
	" mtu=%%d default: 0 (unlimited)\n" \
	" drop packets larger than N bytes\n" \
	" bad_ad=%%d default: 0 (don't add bad ApplicationData)\n" \
	"\n" \
	" seed=%%d default: (use current time)\n" \
	"\n"

	/*
	* global options
	*/
	static struct options
	{
	const char server_addr; / address to forward packets to */
	int server_port; /* port to forward packets to */
	const char listen_addr; / address for accepting client connections */
	int listen_port; /* port for accepting client connections */

	int duplicate; /* duplicate 1 in N packets (none if 0) */
	int delay; /* delay 1 packet in N (none if 0) */
	int delay_ccs; /* delay ChangeCipherSpec */
	int drop; /* drop 1 packet in N (none if 0) */
	int mtu; /* drop packets larger than this */
	int bad_ad; /* inject corrupted ApplicationData record */

	unsigned int seed; /* seed for "random" events */
	} opt;

	static void exit_usage( const char name, const char value )
	{
	if( value == NULL )
	printf( " unknown option or missing value: %s\n", name );
	else
	printf( " option %s: illegal value: %s\n", name, value );

	printf( USAGE );
	exit( 1 );
	}

	static void get_options( int argc, char *argv[] )
	{
	int i;
	char p, q;

	opt.server_addr = DFL_SERVER_ADDR;
	opt.server_port = DFL_SERVER_PORT;
	opt.listen_addr = DFL_LISTEN_ADDR;
	opt.listen_port = DFL_LISTEN_PORT;
	/* Other members default to 0 */

	for( i = 1; i < argc; i++ )
	{
	p = argv[i];
	if( ( q = strchr( p, '=' ) ) == NULL )
	exit_usage( p, NULL );
	*q++ = '\0';

	if( strcmp( p, "server_addr" ) == 0 )
	opt.server_addr = q;
	else if( strcmp( p, "server_port" ) == 0 )
	{
	opt.server_port = atoi( q );
	if( opt.server_port < 1 \|\| opt.server_port > 65535 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "listen_addr" ) == 0 )
	opt.listen_addr = q;
	else if( strcmp( p, "listen_port" ) == 0 )
	{
	opt.listen_port = atoi( q );
	if( opt.listen_port < 1 \|\| opt.listen_port > 65535 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "duplicate" ) == 0 )
	{
	opt.duplicate = atoi( q );
	if( opt.duplicate < 0 \|\| opt.duplicate > 20 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "delay" ) == 0 )
	{
	opt.delay = atoi( q );
	if( opt.delay < 0 \|\| opt.delay > 20 \|\| opt.delay == 1 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "delay_ccs" ) == 0 )
	{
	opt.delay_ccs = atoi( q );
	if( opt.delay_ccs < 0 \|\| opt.delay_ccs > 1 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "drop" ) == 0 )
	{
	opt.drop = atoi( q );
	if( opt.drop < 0 \|\| opt.drop > 20 \|\| opt.drop == 1 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "mtu" ) == 0 )
	{
	opt.mtu = atoi( q );
	if( opt.mtu < 0 \|\| opt.mtu > MAX_MSG_SIZE )
	exit_usage( p, q );
	}
	else if( strcmp( p, "bad_ad" ) == 0 )
	{
	opt.bad_ad = atoi( q );
	if( opt.bad_ad < 0 \|\| opt.bad_ad > 1 )
	exit_usage( p, q );
	}
	else if( strcmp( p, "seed" ) == 0 )
	{
	opt.seed = atoi( q );
	if( opt.seed == 0 )
	exit_usage( p, q );
	}
	else
	exit_usage( p, NULL );
	}
	}

	static const char msg_type( unsigned char msg, size_t len )
	{
	if( len < 1 ) return( "Invalid" );
	switch( msg[0] )
	{
	case SSL_MSG_CHANGE_CIPHER_SPEC: return( "ChangeCipherSpec" );
	case SSL_MSG_ALERT: return( "Alert" );
	case SSL_MSG_APPLICATION_DATA: return( "ApplicationData" );
	case SSL_MSG_HANDSHAKE: break; /* See below */
	default: return( "Unknown" );
	}

	if( len < 13 + 12 ) return( "Invalid handshake" );

	/*
	* Our handshake message are less than 2^16 bytes long, so they should
	* have 0 as the first byte of length, frag_offset and frag_length.
	* Otherwise, assume they are encrypted.
	*/
	if( msg[14] \|\| msg[19] \|\| msg[22] ) return( "Encrypted handshake" );

	switch( msg[13] )
	{
	case SSL_HS_HELLO_REQUEST: return( "HelloRequest" );
	case SSL_HS_CLIENT_HELLO: return( "ClientHello" );
	case SSL_HS_SERVER_HELLO: return( "ServerHello" );
	case SSL_HS_HELLO_VERIFY_REQUEST: return( "HelloVerifyRequest" );
	case SSL_HS_NEW_SESSION_TICKET: return( "NewSessionTicket" );
	case SSL_HS_CERTIFICATE: return( "Certificate" );
	case SSL_HS_SERVER_KEY_EXCHANGE: return( "ServerKeyExchange" );
	case SSL_HS_CERTIFICATE_REQUEST: return( "CertificateRequest" );
	case SSL_HS_SERVER_HELLO_DONE: return( "ServerHelloDone" );
	case SSL_HS_CERTIFICATE_VERIFY: return( "CertificateVerify" );
	case SSL_HS_CLIENT_KEY_EXCHANGE: return( "ClientKeyExchange" );
	case SSL_HS_FINISHED: return( "Finished" );
	default: return( "Unknown handshake" );
	}
	}

	/* Return elapsed time in milliseconds since the first call */
	static unsigned long ellapsed_time( void )
	{
	#if defined(_WIN32)
	return( 0 );
	#else
	static struct timeval ref = { 0, 0 };
	struct timeval now;

	if( ref.tv_sec == 0 && ref.tv_usec == 0 )
	{
	gettimeofday( &ref, NULL );
	return( 0 );
	}

	gettimeofday( &now, NULL );
	return( 1000 * ( now.tv_sec - ref.tv_sec )
	+ ( now.tv_usec - ref.tv_usec ) / 1000 );
	#endif
	}

	typedef struct
	{
	int dst;
	const char *way;
	const char *type;
	unsigned len;
	unsigned char buf[MAX_MSG_SIZE];
	} packet;

	/* Print packet. Outgoing packets come with a reason (forward, dupl, etc.) */
	void print_packet( const packet p, const char why )
	{
	if( why == NULL )
	printf( " %05lu %s %s (%u bytes)\n",
	ellapsed_time(), p->way, p->type, p->len );
	else
	printf( " %s %s (%u bytes): %s\n",
	p->way, p->type, p->len, why );
	fflush( stdout );
	}

	int send_packet( const packet p, const char why )
	{
	int ret;
	int dst = p->dst;

	/* insert corrupted ApplicationData record? */
	if( opt.bad_ad &&
	strcmp( p->type, "ApplicationData" ) == 0 )
	{
	unsigned char buf[MAX_MSG_SIZE];
	memcpy( buf, p->buf, p->len );
	++buf[p->len - 1];

	print_packet( p, "corrupted" );
	if( ( ret = net_send( &dst, buf, p->len ) ) <= 0 )
	{
	printf( " ! net_send returned %d\n", ret );
	return( ret );
	}
	}

	print_packet( p, why );
	if( ( ret = net_send( &dst, p->buf, p->len ) ) <= 0 )
	{
	printf( " ! net_send returned %d\n", ret );
	return( ret );
	}

	/* Don't duplicate Application Data, only handshake covered */
	if( opt.duplicate != 0 &&
	strcmp( p->type, "ApplicationData" ) != 0 &&
	rand() % opt.duplicate == 0 )
	{
	print_packet( p, "duplicated" );

	if( ( ret = net_send( &dst, p->buf, p->len ) ) <= 0 )
	{
	printf( " ! net_send returned %d\n", ret );
	return( ret );
	}
	}

	return( 0 );
	}

	static packet prev;

	void clear_pending( void )
	{
	memset( &prev, 0, sizeof( packet ) );
	}

	int handle_message( const char *way, int dst, int src )
	{
	int ret;
	packet cur;

	/* receive packet */
	if( ( ret = net_recv( &src, cur.buf, sizeof( cur.buf ) ) ) <= 0 )
	{
	printf( " ! net_recv returned %d\n", ret );
	return( ret );
	}

	cur.len = ret;
	cur.type = msg_type( cur.buf, cur.len );
	cur.way = way;
	cur.dst = dst;
	print_packet( &cur, NULL );

	/* do we want to drop, delay, or forward it? */
	if( ( opt.mtu != 0 &&
	cur.len > (unsigned) opt.mtu ) \|\|
	( opt.drop != 0 &&
	strcmp( cur.type, "ApplicationData" ) != 0 &&
	rand() % opt.drop == 0 ) )
	{
	; /* Nothing to do */
	}
	else if( ( opt.delay_ccs == 1 &&
	strcmp( cur.type, "ChangeCipherSpec" ) == 0 ) \|\|
	( opt.delay != 0 &&
	strcmp( cur.type, "ApplicationData" ) != 0 &&
	prev.dst == 0 &&
	rand() % opt.delay == 0 ) )
	{
	memcpy( &prev, &cur, sizeof( packet ) );
	}
	else
	{
	/* forward and possibly duplicate */
	if( ( ret = send_packet( &cur, "forwarded" ) ) != 0 )
	return( ret );

	/* send previously delayed message if any */
	if( prev.dst != 0 )
	{
	ret = send_packet( &prev, "delayed" );
	memset( &prev, 0, sizeof( packet ) );
	if( ret != 0 )
	return( ret );
	}
	}

	return( 0 );
	}

	int main( int argc, char *argv[] )
	{
	int ret;

	int listen_fd = -1;
	int client_fd = -1;
	int server_fd = -1;

	int nb_fds;
	fd_set read_fds;

	get_options( argc, argv );

	/*
	* Decisions to drop/delay/duplicate packets are pseudo-random: dropping
	* exactly 1 in N packets would lead to problems when a flight has exactly
	* N packets: the same packet would be dropped on every resend.
	*
	* In order to be able to reproduce problems reliably, the seed may be
	* specified explicitly.
	*/
	if( opt.seed == 0 )
	{
	opt.seed = time( NULL );
	printf( " . Pseudo-random seed: %u\n", opt.seed );
	}

	srand( opt.seed );

	/*
	* 0. "Connect" to the server
	*/
	printf( " . Connect to server on UDP/%s/%d ...",
	opt.server_addr, opt.server_port );
	fflush( stdout );

	if( ( ret = net_connect( &server_fd, opt.server_addr, opt.server_port,
	NET_PROTO_UDP ) ) != 0 )
	{
	printf( " failed\n ! net_connect returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 1. Setup the "listening" UDP socket
	*/
	printf( " . Bind on UDP/%s/%d ...",
	opt.listen_addr, opt.listen_port );
	fflush( stdout );

	if( ( ret = net_bind( &listen_fd, opt.listen_addr, opt.listen_port,
	NET_PROTO_UDP ) ) != 0 )
	{
	printf( " failed\n ! net_bind returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 2. Wait until a client connects
	*/
	accept:
	printf( " . Waiting for a remote connection ..." );
	fflush( stdout );

	if( ( ret = net_accept( listen_fd, &client_fd, NULL ) ) != 0 )
	{
	printf( " failed\n ! net_accept returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );
	fflush( stdout );

	printf( " . Re-bind on UDP/%s/%d ...",
	opt.listen_addr, opt.listen_port );
	fflush( stdout );

	if( ( ret = net_bind( &listen_fd, opt.listen_addr, opt.listen_port,
	NET_PROTO_UDP ) ) != 0 )
	{
	printf( " failed\n ! net_bind returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 3. Forward packets forever (kill the process to terminate it)
	*/
	nb_fds = client_fd;
	if( nb_fds < server_fd )
	nb_fds = server_fd;
	if( nb_fds < listen_fd )
	nb_fds = listen_fd;
	++nb_fds;

	while( 1 )
	{
	FD_ZERO( &read_fds );
	FD_SET( server_fd, &read_fds );
	FD_SET( client_fd, &read_fds );
	FD_SET( listen_fd, &read_fds );

	if( ( ret = select( nb_fds, &read_fds, NULL, NULL, NULL ) ) <= 0 )
	{
	perror( "select" );
	goto exit;
	}

	if( FD_ISSET( listen_fd, &read_fds ) )
	{
	clear_pending();
	goto accept;
	}

	if( FD_ISSET( client_fd, &read_fds ) )
	{
	if( ( ret = handle_message( "S <- C",
	server_fd, client_fd ) ) != 0 )
	goto exit;
	}

	if( FD_ISSET( server_fd, &read_fds ) )
	{
	if( ( ret = handle_message( "S -> C",
	client_fd, server_fd ) ) != 0 )
	goto exit;
	}
	}

	exit:

	#ifdef POLARSSL_ERROR_C
	if( ret != 0 )
	{
	char error_buf[100];
	polarssl_strerror( ret, error_buf, 100 );
	printf( "Last error was: -0x%04X - %s\n\n", - ret, error_buf );
	fflush( stdout );
	}
	#endif

	if( client_fd != -1 )
	net_close( client_fd );

	if( listen_fd != -1 )
	net_close( listen_fd );

	#if defined(_WIN32)
	printf( " Press Enter to exit this program.\n" );
	fflush( stdout ); getchar();
	#endif

	return( ret != 0 );
	}

	#endif /* POLARSSL_NET_C */