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mbedtls/programs/test/udp_proxy.c
Manuel Pégourié-Gonnard 14134281df Fix bug with UDP proxy not forwarding enough 
We previously introduced a safety check ensuring that if a datagram had
already been dropped twice, it would no longer be dropped or delayed
after that.

This missed an edge case: if a datagram is dropped once, it can be
delayed any number of times. Since "delay" is not defined in terms of
time (x seconds) but in terms of ordering with respect to other messages
(will be forwarded after the next message is forwarded), depending on
the RNG results this could result in an endless loop where all messages
are delayed until the next, which is itself delayed, etc. and no message
is ever forwarded.

The probability of this happening n times in a row is (1/d)^n, where d
is the value passed as delay=d, so for delay=5 and n=5 it's around 0.03%
which seems small but we still happened on such an occurrence in real
life:

    tests/ssl-opt.sh --seed 1625061502 -f 'DTLS proxy: 3d, min handshake, resumption$'

results (according to debug statements added for the investigation) in
the ClientHello of the second handshake being dropped once then delayed
5 times, after which the client stops re-trying and the test fails for
no interesting reason.

Make sure this doesn't happen again by putting a cap on the number of
times we fail to forward a given datagram immediately.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
2021-07-08 12:42:59 +02:00

1021 lines
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/*
* UDP proxy: emulate an unreliable UDP connexion for DTLS testing
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Warning: this is an internal utility program we use for tests.
* It does break some abstractions from the NET layer, and is thus NOT an
* example of good general usage.
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define mbedtls_time time
#define mbedtls_time_t time_t
#define mbedtls_printf printf
#define mbedtls_calloc calloc
#define mbedtls_free free
#define mbedtls_exit exit
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif /* MBEDTLS_PLATFORM_C */
#if !defined(MBEDTLS_NET_C)
int main( void )
{
mbedtls_printf( "MBEDTLS_NET_C not defined.\n" );
mbedtls_exit( 0 );
}
#else
#include "mbedtls/net_sockets.h"
#include "mbedtls/error.h"
#include "mbedtls/ssl.h"
#include "mbedtls/timing.h"
#include <string.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 */
#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 DFL_PACK 0
#if defined(MBEDTLS_TIMING_C)
#define USAGE_PACK \
" pack=%%d default: 0 (don't pack)\n" \
" options: t > 0 (pack for t milliseconds)\n"
#else
#define USAGE_PACK
#endif
#define USAGE \
"\n usage: udp_proxy param=<>...\n" \
"\n acceptable parameters:\n" \
" server_addr=%%s default: localhost\n" \
" server_port=%%d default: 4433\n" \
" listen_addr=%%s 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=0/1 default: 0 (don't delay ChangeCipherSpec)\n" \
" delay_cli=%%s Handshake message from client that should be\n"\
" delayed. Possible values are 'ClientHello',\n" \
" 'Certificate', 'CertificateVerify', and\n" \
" 'ClientKeyExchange'.\n" \
" May be used multiple times, even for the same\n"\
" message, in which case the respective message\n"\
" gets delayed multiple times.\n" \
" delay_srv=%%s Handshake message from server that should be\n"\
" delayed. Possible values are 'HelloRequest',\n"\
" 'ServerHello', 'ServerHelloDone', 'Certificate'\n"\
" 'ServerKeyExchange', 'NewSessionTicket',\n"\
" 'HelloVerifyRequest' and ''CertificateRequest'.\n"\
" May be used multiple times, even for the same\n"\
" message, in which case the respective message\n"\
" gets delayed multiple times.\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=0/1 default: 0 (don't add bad ApplicationData)\n" \
" bad_cid=%%d default: 0 (don't corrupt Connection IDs)\n" \
" duplicate 1:N packets containing a CID,\n" \
" modifying CID in first instance of the packet.\n" \
" protect_hvr=0/1 default: 0 (don't protect HelloVerifyRequest)\n" \
" protect_len=%%d default: (don't protect packets of this size)\n" \
" inject_clihlo=0/1 default: 0 (don't inject fake ClientHello)\n" \
"\n" \
" seed=%%d default: (use current time)\n" \
USAGE_PACK \
"\n"
/*
* global options
*/
#define MAX_DELAYED_HS 10
static struct options
{
const char *server_addr; /* address to forward packets to */
const char *server_port; /* port to forward packets to */
const char *listen_addr; /* address for accepting client connections */
const char *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 */
char* delay_cli[MAX_DELAYED_HS]; /* handshake types of messages from
* client that should be delayed. */
uint8_t delay_cli_cnt; /* Number of entries in delay_cli. */
char* delay_srv[MAX_DELAYED_HS]; /* handshake types of messages from
* server that should be delayed. */
uint8_t delay_srv_cnt; /* Number of entries in delay_srv. */
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 bad_cid; /* inject corrupted CID record */
int protect_hvr; /* never drop or delay HelloVerifyRequest */
int protect_len; /* never drop/delay packet of the given size*/
int inject_clihlo; /* inject fake ClientHello after handshake */
unsigned pack; /* merge packets into single datagram for
* at most \c merge milliseconds if > 0 */
unsigned int seed; /* seed for "random" events */
} opt;
static void exit_usage( const char *name, const char *value )
{
if( value == NULL )
mbedtls_printf( " unknown option or missing value: %s\n", name );
else
mbedtls_printf( " option %s: illegal value: %s\n", name, value );
mbedtls_printf( USAGE );
mbedtls_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;
opt.pack = DFL_PACK;
/* Other members default to 0 */
opt.delay_cli_cnt = 0;
opt.delay_srv_cnt = 0;
memset( opt.delay_cli, 0, sizeof( opt.delay_cli ) );
memset( opt.delay_srv, 0, sizeof( opt.delay_srv ) );
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 = q;
else if( strcmp( p, "listen_addr" ) == 0 )
opt.listen_addr = q;
else if( strcmp( p, "listen_port" ) == 0 )
opt.listen_port = 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, "delay_cli" ) == 0 ||
strcmp( p, "delay_srv" ) == 0 )
{
uint8_t *delay_cnt;
char **delay_list;
size_t len;
char *buf;
if( strcmp( p, "delay_cli" ) == 0 )
{
delay_cnt = &opt.delay_cli_cnt;
delay_list = opt.delay_cli;
}
else
{
delay_cnt = &opt.delay_srv_cnt;
delay_list = opt.delay_srv;
}
if( *delay_cnt == MAX_DELAYED_HS )
{
mbedtls_printf( " too many uses of %s: only %d allowed\n",
p, MAX_DELAYED_HS );
exit_usage( p, NULL );
}
len = strlen( q );
buf = mbedtls_calloc( 1, len + 1 );
if( buf == NULL )
{
mbedtls_printf( " Allocation failure\n" );
exit( 1 );
}
memcpy( buf, q, len + 1 );
delay_list[ (*delay_cnt)++ ] = buf;
}
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, "pack" ) == 0 )
{
#if defined(MBEDTLS_TIMING_C)
opt.pack = (unsigned) atoi( q );
#else
mbedtls_printf( " option pack only defined if MBEDTLS_TIMING_C is enabled\n" );
exit( 1 );
#endif
}
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 );
}
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
else if( strcmp( p, "bad_cid" ) == 0 )
{
opt.bad_cid = (unsigned) atoi( q );
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
else if( strcmp( p, "protect_hvr" ) == 0 )
{
opt.protect_hvr = atoi( q );
if( opt.protect_hvr < 0 || opt.protect_hvr > 1 )
exit_usage( p, q );
}
else if( strcmp( p, "protect_len" ) == 0 )
{
opt.protect_len = atoi( q );
if( opt.protect_len < 0 )
exit_usage( p, q );
}
else if( strcmp( p, "inject_clihlo" ) == 0 )
{
opt.inject_clihlo = atoi( q );
if( opt.inject_clihlo < 0 || opt.inject_clihlo > 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 MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC: return( "ChangeCipherSpec" );
case MBEDTLS_SSL_MSG_ALERT: return( "Alert" );
case MBEDTLS_SSL_MSG_APPLICATION_DATA: return( "ApplicationData" );
case MBEDTLS_SSL_MSG_CID: return( "CID" );
case MBEDTLS_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 MBEDTLS_SSL_HS_HELLO_REQUEST: return( "HelloRequest" );
case MBEDTLS_SSL_HS_CLIENT_HELLO: return( "ClientHello" );
case MBEDTLS_SSL_HS_SERVER_HELLO: return( "ServerHello" );
case MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST: return( "HelloVerifyRequest" );
case MBEDTLS_SSL_HS_NEW_SESSION_TICKET: return( "NewSessionTicket" );
case MBEDTLS_SSL_HS_CERTIFICATE: return( "Certificate" );
case MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE: return( "ServerKeyExchange" );
case MBEDTLS_SSL_HS_CERTIFICATE_REQUEST: return( "CertificateRequest" );
case MBEDTLS_SSL_HS_SERVER_HELLO_DONE: return( "ServerHelloDone" );
case MBEDTLS_SSL_HS_CERTIFICATE_VERIFY: return( "CertificateVerify" );
case MBEDTLS_SSL_HS_CLIENT_KEY_EXCHANGE: return( "ClientKeyExchange" );
case MBEDTLS_SSL_HS_FINISHED: return( "Finished" );
default: return( "Unknown handshake" );
}
}
#if defined(MBEDTLS_TIMING_C)
/* Return elapsed time in milliseconds since the first call */
static unsigned ellapsed_time( void )
{
static int initialized = 0;
static struct mbedtls_timing_hr_time hires;
if( initialized == 0 )
{
(void) mbedtls_timing_get_timer( &hires, 1 );
initialized = 1;
return( 0 );
}
return( mbedtls_timing_get_timer( &hires, 0 ) );
}
typedef struct
{
mbedtls_net_context *ctx;
const char *description;
unsigned packet_lifetime;
unsigned num_datagrams;
unsigned char data[MAX_MSG_SIZE];
size_t len;
} ctx_buffer;
static ctx_buffer outbuf[2];
static int ctx_buffer_flush( ctx_buffer *buf )
{
int ret;
mbedtls_printf( " %05u flush %s: %u bytes, %u datagrams, last %u ms\n",
ellapsed_time(), buf->description,
(unsigned) buf->len, buf->num_datagrams,
ellapsed_time() - buf->packet_lifetime );
ret = mbedtls_net_send( buf->ctx, buf->data, buf->len );
buf->len = 0;
buf->num_datagrams = 0;
return( ret );
}
static unsigned ctx_buffer_time_remaining( ctx_buffer *buf )
{
unsigned const cur_time = ellapsed_time();
if( buf->num_datagrams == 0 )
return( (unsigned) -1 );
if( cur_time - buf->packet_lifetime >= opt.pack )
return( 0 );
return( opt.pack - ( cur_time - buf->packet_lifetime ) );
}
static int ctx_buffer_append( ctx_buffer *buf,
const unsigned char * data,
size_t len )
{
int ret;
if( len > (size_t) INT_MAX )
return( -1 );
if( len > sizeof( buf->data ) )
{
mbedtls_printf( " ! buffer size %u too large (max %u)\n",
(unsigned) len, (unsigned) sizeof( buf->data ) );
return( -1 );
}
if( sizeof( buf->data ) - buf->len < len )
{
if( ( ret = ctx_buffer_flush( buf ) ) <= 0 )
{
mbedtls_printf( "ctx_buffer_flush failed with -%#04x", (unsigned int) -ret );
return( ret );
}
}
memcpy( buf->data + buf->len, data, len );
buf->len += len;
if( ++buf->num_datagrams == 1 )
buf->packet_lifetime = ellapsed_time();
return( (int) len );
}
#endif /* MBEDTLS_TIMING_C */
static int dispatch_data( mbedtls_net_context *ctx,
const unsigned char * data,
size_t len )
{
int ret;
#if defined(MBEDTLS_TIMING_C)
ctx_buffer *buf = NULL;
if( opt.pack > 0 )
{
if( outbuf[0].ctx == ctx )
buf = &outbuf[0];
else if( outbuf[1].ctx == ctx )
buf = &outbuf[1];
if( buf == NULL )
return( -1 );
return( ctx_buffer_append( buf, data, len ) );
}
#endif /* MBEDTLS_TIMING_C */
ret = mbedtls_net_send( ctx, data, len );
if( ret < 0 )
{
mbedtls_printf( "net_send returned -%#04x\n", (unsigned int) -ret );
}
return( ret );
}
typedef struct
{
mbedtls_net_context *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 defined(MBEDTLS_TIMING_C)
if( why == NULL )
mbedtls_printf( " %05u dispatch %s %s (%u bytes)\n",
ellapsed_time(), p->way, p->type, p->len );
else
mbedtls_printf( " %05u dispatch %s %s (%u bytes): %s\n",
ellapsed_time(), p->way, p->type, p->len, why );
#else
if( why == NULL )
mbedtls_printf( " dispatch %s %s (%u bytes)\n",
p->way, p->type, p->len );
else
mbedtls_printf( " dispatch %s %s (%u bytes): %s\n",
p->way, p->type, p->len, why );
#endif
fflush( stdout );
}
/*
* In order to test the server's behaviour when receiving a ClientHello after
* the connection is established (this could be a hard reset from the client,
* but the server must not drop the existing connection before establishing
* client reachability, see RFC 6347 Section 4.2.8), we memorize the first
* ClientHello we see (which can't have a cookie), then replay it after the
* first ApplicationData record - then we're done.
*
* This is controlled by the inject_clihlo option.
*
* We want an explicit state and a place to store the packet.
*/
typedef enum {
ICH_INIT, /* haven't seen the first ClientHello yet */
ICH_CACHED, /* cached the initial ClientHello */
ICH_INJECTED, /* ClientHello already injected, done */
} inject_clihlo_state_t;
static inject_clihlo_state_t inject_clihlo_state;
static packet initial_clihlo;
int send_packet( const packet *p, const char *why )
{
int ret;
mbedtls_net_context *dst = p->dst;
/* save initial ClientHello? */
if( opt.inject_clihlo != 0 &&
inject_clihlo_state == ICH_INIT &&
strcmp( p->type, "ClientHello" ) == 0 )
{
memcpy( &initial_clihlo, p, sizeof( packet ) );
inject_clihlo_state = ICH_CACHED;
}
/* insert corrupted CID record? */
if( opt.bad_cid != 0 &&
strcmp( p->type, "CID" ) == 0 &&
( rand() % opt.bad_cid ) == 0 )
{
unsigned char buf[MAX_MSG_SIZE];
memcpy( buf, p->buf, p->len );
/* The CID resides at offset 11 in the DTLS record header. */
buf[11] ^= 1;
print_packet( p, "modified CID" );
if( ( ret = dispatch_data( dst, buf, p->len ) ) <= 0 )
{
mbedtls_printf( " ! dispatch returned %d\n", ret );
return( ret );
}
}
/* 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 );
if( p->len <= 13 )
{
mbedtls_printf( " ! can't corrupt empty AD record" );
}
else
{
++buf[13];
print_packet( p, "corrupted" );
}
if( ( ret = dispatch_data( dst, buf, p->len ) ) <= 0 )
{
mbedtls_printf( " ! dispatch returned %d\n", ret );
return( ret );
}
}
print_packet( p, why );
if( ( ret = dispatch_data( dst, p->buf, p->len ) ) <= 0 )
{
mbedtls_printf( " ! dispatch 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 = dispatch_data( dst, p->buf, p->len ) ) <= 0 )
{
mbedtls_printf( " ! dispatch returned %d\n", ret );
return( ret );
}
}
/* Inject ClientHello after first ApplicationData */
if( opt.inject_clihlo != 0 &&
inject_clihlo_state == ICH_CACHED &&
strcmp( p->type, "ApplicationData" ) == 0 )
{
print_packet( &initial_clihlo, "injected" );
if( ( ret = dispatch_data( dst, initial_clihlo.buf,
initial_clihlo.len ) ) <= 0 )
{
mbedtls_printf( " ! dispatch returned %d\n", ret );
return( ret );
}
inject_clihlo_state = ICH_INJECTED;
}
return( 0 );
}
#define MAX_DELAYED_MSG 5
static size_t prev_len;
static packet prev[MAX_DELAYED_MSG];
void clear_pending( void )
{
memset( &prev, 0, sizeof( prev ) );
prev_len = 0;
}
void delay_packet( packet *delay )
{
if( prev_len == MAX_DELAYED_MSG )
return;
memcpy( &prev[prev_len++], delay, sizeof( packet ) );
}
int send_delayed()
{
uint8_t offset;
int ret;
for( offset = 0; offset < prev_len; offset++ )
{
ret = send_packet( &prev[offset], "delayed" );
if( ret != 0 )
return( ret );
}
clear_pending();
return( 0 );
}
/*
* Avoid dropping or delaying a packet that was already dropped or delayed
* ("held") twice: this only results in uninteresting timeouts. We can't rely
* on type to identify packets, since during renegotiation they're all
* encrypted. So, rely on size mod 2048 (which is usually just size).
*
* We only hold packets at the level of entire datagrams, not at the level
* of records. In particular, if the peer changes the way it packs multiple
* records into a single datagram, we don't necessarily count the number of
* times a record has been held correctly. However, the only known reason
* why a peer would change datagram packing is disabling the latter on
* retransmission, in which case we'd hold involved records at most
* HOLD_MAX + 1 times.
*/
static unsigned char held[2048] = { 0 };
#define HOLD_MAX 2
int handle_message( const char *way,
mbedtls_net_context *dst,
mbedtls_net_context *src )
{
int ret;
packet cur;
size_t id;
uint8_t delay_idx;
char ** delay_list;
uint8_t delay_list_len;
/* receive packet */
if( ( ret = mbedtls_net_recv( src, cur.buf, sizeof( cur.buf ) ) ) <= 0 )
{
mbedtls_printf( " ! mbedtls_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 );
id = cur.len % sizeof( held );
if( strcmp( way, "S <- C" ) == 0 )
{
delay_list = opt.delay_cli;
delay_list_len = opt.delay_cli_cnt;
}
else
{
delay_list = opt.delay_srv;
delay_list_len = opt.delay_srv_cnt;
}
/* Check if message type is in the list of messages
* that should be delayed */
for( delay_idx = 0; delay_idx < delay_list_len; delay_idx++ )
{
if( delay_list[ delay_idx ] == NULL )
continue;
if( strcmp( delay_list[ delay_idx ], cur.type ) == 0 )
{
/* Delay message */
delay_packet( &cur );
/* Remove entry from list */
mbedtls_free( delay_list[delay_idx] );
delay_list[delay_idx] = NULL;
return( 0 );
}
}
/* do we want to drop, delay, or forward it? */
if( ( opt.mtu != 0 &&
cur.len > (unsigned) opt.mtu ) ||
( opt.drop != 0 &&
strcmp( cur.type, "CID" ) != 0 &&
strcmp( cur.type, "ApplicationData" ) != 0 &&
! ( opt.protect_hvr &&
strcmp( cur.type, "HelloVerifyRequest" ) == 0 ) &&
cur.len != (size_t) opt.protect_len &&
held[id] < HOLD_MAX &&
rand() % opt.drop == 0 ) )
{
++held[id];
}
else if( ( opt.delay_ccs == 1 &&
strcmp( cur.type, "ChangeCipherSpec" ) == 0 ) ||
( opt.delay != 0 &&
strcmp( cur.type, "CID" ) != 0 &&
strcmp( cur.type, "ApplicationData" ) != 0 &&
! ( opt.protect_hvr &&
strcmp( cur.type, "HelloVerifyRequest" ) == 0 ) &&
cur.len != (size_t) opt.protect_len &&
held[id] < HOLD_MAX &&
rand() % opt.delay == 0 ) )
{
++held[id];
delay_packet( &cur );
}
else
{
/* forward and possibly duplicate */
if( ( ret = send_packet( &cur, "forwarded" ) ) != 0 )
return( ret );
/* send previously delayed messages if any */
ret = send_delayed();
if( ret != 0 )
return( ret );
}
return( 0 );
}
int main( int argc, char *argv[] )
{
int ret = 1;
int exit_code = MBEDTLS_EXIT_FAILURE;
uint8_t delay_idx;
mbedtls_net_context listen_fd, client_fd, server_fd;
#if defined( MBEDTLS_TIMING_C )
struct timeval tm;
#endif
struct timeval *tm_ptr = NULL;
int nb_fds;
fd_set read_fds;
mbedtls_net_init( &listen_fd );
mbedtls_net_init( &client_fd );
mbedtls_net_init( &server_fd );
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 = (unsigned int) time( NULL );
mbedtls_printf( " . Pseudo-random seed: %u\n", opt.seed );
}
srand( opt.seed );
/*
* 0. "Connect" to the server
*/
mbedtls_printf( " . Connect to server on UDP/%s/%s ...",
opt.server_addr, opt.server_port );
fflush( stdout );
if( ( ret = mbedtls_net_connect( &server_fd, opt.server_addr, opt.server_port,
MBEDTLS_NET_PROTO_UDP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_connect returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* 1. Setup the "listening" UDP socket
*/
mbedtls_printf( " . Bind on UDP/%s/%s ...",
opt.listen_addr, opt.listen_port );
fflush( stdout );
if( ( ret = mbedtls_net_bind( &listen_fd, opt.listen_addr, opt.listen_port,
MBEDTLS_NET_PROTO_UDP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_bind returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* 2. Wait until a client connects
*/
accept:
mbedtls_net_free( &client_fd );
mbedtls_printf( " . Waiting for a remote connection ..." );
fflush( stdout );
if( ( ret = mbedtls_net_accept( &listen_fd, &client_fd,
NULL, 0, NULL ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_accept returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* 3. Forward packets forever (kill the process to terminate it)
*/
clear_pending();
memset( held, 0, sizeof( held ) );
nb_fds = client_fd.fd;
if( nb_fds < server_fd.fd )
nb_fds = server_fd.fd;
if( nb_fds < listen_fd.fd )
nb_fds = listen_fd.fd;
++nb_fds;
#if defined(MBEDTLS_TIMING_C)
if( opt.pack > 0 )
{
outbuf[0].ctx = &server_fd;
outbuf[0].description = "S <- C";
outbuf[0].num_datagrams = 0;
outbuf[0].len = 0;
outbuf[1].ctx = &client_fd;
outbuf[1].description = "S -> C";
outbuf[1].num_datagrams = 0;
outbuf[1].len = 0;
}
#endif /* MBEDTLS_TIMING_C */
while( 1 )
{
#if defined(MBEDTLS_TIMING_C)
if( opt.pack > 0 )
{
unsigned max_wait_server, max_wait_client, max_wait;
max_wait_server = ctx_buffer_time_remaining( &outbuf[0] );
max_wait_client = ctx_buffer_time_remaining( &outbuf[1] );
max_wait = (unsigned) -1;
if( max_wait_server == 0 )
ctx_buffer_flush( &outbuf[0] );
else
max_wait = max_wait_server;
if( max_wait_client == 0 )
ctx_buffer_flush( &outbuf[1] );
else
{
if( max_wait_client < max_wait )
max_wait = max_wait_client;
}
if( max_wait != (unsigned) -1 )
{
tm.tv_sec = max_wait / 1000;
tm.tv_usec = ( max_wait % 1000 ) * 1000;
tm_ptr = &tm;
}
else
{
tm_ptr = NULL;
}
}
#endif /* MBEDTLS_TIMING_C */
FD_ZERO( &read_fds );
FD_SET( server_fd.fd, &read_fds );
FD_SET( client_fd.fd, &read_fds );
FD_SET( listen_fd.fd, &read_fds );
if( ( ret = select( nb_fds, &read_fds, NULL, NULL, tm_ptr ) ) < 0 )
{
perror( "select" );
goto exit;
}
if( FD_ISSET( listen_fd.fd, &read_fds ) )
goto accept;
if( FD_ISSET( client_fd.fd, &read_fds ) )
{
if( ( ret = handle_message( "S <- C",
&server_fd, &client_fd ) ) != 0 )
goto accept;
}
if( FD_ISSET( server_fd.fd, &read_fds ) )
{
if( ( ret = handle_message( "S -> C",
&client_fd, &server_fd ) ) != 0 )
goto accept;
}
}
exit_code = MBEDTLS_EXIT_SUCCESS;
exit:
#ifdef MBEDTLS_ERROR_C
if( exit_code != MBEDTLS_EXIT_SUCCESS )
{
char error_buf[100];
mbedtls_strerror( ret, error_buf, 100 );
mbedtls_printf( "Last error was: -0x%04X - %s\n\n", (unsigned int) -ret, error_buf );
fflush( stdout );
}
#endif
for( delay_idx = 0; delay_idx < MAX_DELAYED_HS; delay_idx++ )
{
mbedtls_free( opt.delay_cli[delay_idx] );
mbedtls_free( opt.delay_srv[delay_idx] );
}
mbedtls_net_free( &client_fd );
mbedtls_net_free( &server_fd );
mbedtls_net_free( &listen_fd );
#if defined(_WIN32)
mbedtls_printf( " Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
mbedtls_exit( exit_code );
}
#endif /* MBEDTLS_NET_C */
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