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proxy: avoid always dropping the same packet

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Manuel Pégourié-Gonnard 2014-09-26 12:08:36 +02:00 committed by Paul Bakker
parent 08a1d4bce1
commit ae666c5092
1 changed files with 45 additions and 1 deletions
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46
programs/test/udp_proxy.c
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@ -351,10 +351,49 @@ void clear_pending( void )
memset( &prev, 0, sizeof( packet ) );
}
/*
* Avoid dropping or delaying a packet that was already dropped 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).
*/
static unsigned char dropped[2048] = { 0 };
#define DROP_MAX 2
/*
* OpenSSL groups packets in a datagram the first time it sends them, but not
* when it resends them. Count every record as seen the first time.
*/
void update_dropped( const packet *p )
{
size_t id = p->len % sizeof( dropped );
++dropped[id];
const unsigned char *end = p->buf + p->len;
const unsigned char *cur = p->buf;
size_t len = ( ( cur[11] << 8 ) | cur[12] ) + 13;
/* Avoid counting single record twice */
if( len == p->len )
return;
while( cur < end )
{
size_t len = ( ( cur[11] << 8 ) | cur[12] ) + 13;
id = len % sizeof( dropped );
++dropped[id];
cur += len;
}
}
int handle_message( const char *way, int dst, int src )
{
int ret;
packet cur;
size_t id;
/* receive packet */
if( ( ret = net_recv( &src, cur.buf, sizeof( cur.buf ) ) ) <= 0 )
@ -369,6 +408,8 @@ int handle_message( const char *way, int dst, int src )
cur.dst = dst;
print_packet( &cur, NULL );
id = cur.len % sizeof( dropped );
/* do we want to drop, delay, or forward it? */
if( ( opt.mtu != 0 &&
cur.len > (unsigned) opt.mtu ) ||
@ -376,9 +417,10 @@ int handle_message( const char *way, int dst, int src )
strcmp( cur.type, "ApplicationData" ) != 0 &&
! ( opt.protect_hvr &&
strcmp( cur.type, "HelloVerifyRequest" ) == 0 ) &&
dropped[id] < DROP_MAX &&
rand() % opt.drop == 0 ) )
{
; /* Nothing to do */
update_dropped( &cur );
}
else if( ( opt.delay_ccs == 1 &&
strcmp( cur.type, "ChangeCipherSpec" ) == 0 ) ||
@ -387,6 +429,7 @@ int handle_message( const char *way, int dst, int src )
! ( opt.protect_hvr &&
strcmp( cur.type, "HelloVerifyRequest" ) == 0 ) &&
prev.dst == 0 &&
dropped[id] < DROP_MAX &&
rand() % opt.delay == 0 ) )
{
memcpy( &prev, &cur, sizeof( packet ) );
@ -526,6 +569,7 @@ accept:
if( FD_ISSET( listen_fd, &read_fds ) )
{
clear_pending();
memset( dropped, 0, sizeof( dropped ) );
goto accept;
}