static void
gotError( tr_peerIo * io,
short what,
void * vhandshake )
{
int errcode = errno;
tr_handshake * handshake = vhandshake;
if( io->utp_socket && !io->isIncoming && handshake->state == AWAITING_YB ) {
/* This peer probably doesn't speak uTP. */
tr_torrent *tor =
tr_peerIoHasTorrentHash( io ) ?
tr_torrentFindFromHash( handshake->session,
tr_peerIoGetTorrentHash( io ) ) :
NULL;
/* Don't mark a peer as non-uTP unless it's really a connect failure. */
if( tor && ( errcode == ETIMEDOUT || errcode == ECONNREFUSED ) ) {
tr_torrentLock( tor );
tr_peerMgrSetUtpFailed( tor,
tr_peerIoGetAddress( io, NULL ),
TRUE );
tr_torrentUnlock( tor );
}
if( !tr_peerIoReconnect( handshake->io ) ) {
uint8_t msg[HANDSHAKE_SIZE];
buildHandshakeMessage( handshake, msg );
handshake->haveSentBitTorrentHandshake = 1;
setReadState( handshake, AWAITING_HANDSHAKE );
tr_peerIoWriteBytes( handshake->io, msg, sizeof( msg ), FALSE );
}
}
/* if the error happened while we were sending a public key, we might
* have encountered a peer that doesn't do encryption... reconnect and
* try a plaintext handshake */
if( ( ( handshake->state == AWAITING_YB )
|| ( handshake->state == AWAITING_VC ) )
&& ( handshake->encryptionMode != TR_ENCRYPTION_REQUIRED )
&& ( !tr_peerIoReconnect( handshake->io ) ) )
{
uint8_t msg[HANDSHAKE_SIZE];
dbgmsg( handshake, "handshake failed, trying plaintext..." );
buildHandshakeMessage( handshake, msg );
handshake->haveSentBitTorrentHandshake = 1;
setReadState( handshake, AWAITING_HANDSHAKE );
tr_peerIoWriteBytes( handshake->io, msg, sizeof( msg ), FALSE );
}
else
{
dbgmsg( handshake, "libevent got an error what==%d, errno=%d (%s)",
(int)what, errno, tr_strerror( errno ) );
tr_handshakeDone( handshake, FALSE );
}
}
static int
readYa( tr_handshake * handshake,
struct evbuffer * inbuf )
{
uint8_t ya[KEY_LEN];
uint8_t * walk, outbuf[KEY_LEN + PadB_MAXLEN];
const uint8_t *myKey, *secret;
int len;
dbgmsg( handshake, "in readYa... need %d, have %zu",
KEY_LEN, evbuffer_get_length( inbuf ) );
if( evbuffer_get_length( inbuf ) < KEY_LEN )
return READ_LATER;
/* read the incoming peer's public key */
evbuffer_remove( inbuf, ya, KEY_LEN );
secret = tr_cryptoComputeSecret( handshake->crypto, ya );
memcpy( handshake->mySecret, secret, KEY_LEN );
tr_sha1( handshake->myReq1, "req1", 4, secret, KEY_LEN, NULL );
dbgmsg( handshake, "sending B->A: Diffie Hellman Yb, PadB" );
/* send our public key to the peer */
walk = outbuf;
myKey = tr_cryptoGetMyPublicKey( handshake->crypto, &len );
memcpy( walk, myKey, len );
walk += len;
len = tr_cryptoRandInt( PadB_MAXLEN );
tr_cryptoRandBuf( walk, len );
walk += len;
setReadState( handshake, AWAITING_PAD_A );
tr_peerIoWriteBytes( handshake->io, outbuf, walk - outbuf, FALSE );
return READ_NOW;
}
void
tr_peerIoWriteUint32( tr_peerIo * io,
struct evbuffer * outbuf,
uint32_t writeme )
{
const uint32_t tmp = htonl( writeme );
tr_peerIoWriteBytes( io, outbuf, &tmp, sizeof( uint32_t ) );
}
tr_handshake*
tr_handshakeNew (tr_peerIo * io,
tr_encryption_mode encryptionMode,
handshakeDoneCB doneCB,
void * doneUserData)
{
tr_handshake * handshake;
tr_session * session = tr_peerIoGetSession (io);
handshake = tr_new0 (tr_handshake, 1);
handshake->io = io;
handshake->crypto = tr_peerIoGetCrypto (io);
handshake->encryptionMode = encryptionMode;
handshake->doneCB = doneCB;
handshake->doneUserData = doneUserData;
handshake->session = session;
handshake->timeout_timer = evtimer_new (session->event_base, handshakeTimeout, handshake);
tr_timerAdd (handshake->timeout_timer, HANDSHAKE_TIMEOUT_SEC, 0);
tr_peerIoRef (io); /* balanced by the unref in tr_handshakeFree */
tr_peerIoSetIOFuncs (handshake->io, canRead, NULL, gotError, handshake);
tr_peerIoSetEncryption (io, PEER_ENCRYPTION_NONE);
if (tr_peerIoIsIncoming (handshake->io))
{
setReadState (handshake, AWAITING_HANDSHAKE);
}
else if (encryptionMode != TR_CLEAR_PREFERRED)
{
sendYa (handshake);
}
else
{
uint8_t msg[HANDSHAKE_SIZE];
buildHandshakeMessage (handshake, msg);
handshake->haveSentBitTorrentHandshake = 1;
setReadState (handshake, AWAITING_HANDSHAKE);
tr_peerIoWriteBytes (handshake->io, msg, sizeof (msg), false);
}
return handshake;
}
/* 1 A->B: Diffie Hellman Ya, PadA */
static void
sendYa( tr_handshake * handshake )
{
int len;
const uint8_t * public_key;
char outbuf[ KEY_LEN + PadA_MAXLEN ], *walk=outbuf;
/* add our public key (Ya) */
public_key = tr_cryptoGetMyPublicKey( handshake->crypto, &len );
assert( len == KEY_LEN );
assert( public_key );
memcpy( walk, public_key, len );
walk += len;
/* add some bullshit padding */
len = tr_cryptoRandInt( PadA_MAXLEN );
tr_cryptoRandBuf( walk, len );
walk += len;
/* send it */
setReadState( handshake, AWAITING_YB );
tr_peerIoWriteBytes( handshake->io, outbuf, walk - outbuf, FALSE );
}
static int
readHandshake( tr_handshake * handshake,
struct evbuffer * inbuf )
{
uint8_t pstrlen;
uint8_t * pstr;
uint8_t reserved[HANDSHAKE_FLAGS_LEN];
uint8_t hash[SHA_DIGEST_LENGTH];
dbgmsg( handshake, "payload: need %d, got %zu",
INCOMING_HANDSHAKE_LEN, evbuffer_get_length( inbuf ) );
if( evbuffer_get_length( inbuf ) < INCOMING_HANDSHAKE_LEN )
return READ_LATER;
handshake->haveReadAnythingFromPeer = TRUE;
pstrlen = evbuffer_pullup( inbuf, 1 )[0]; /* peek, don't read. We may be
handing inbuf to AWAITING_YA */
if( pstrlen == 19 ) /* unencrypted */
{
tr_peerIoSetEncryption( handshake->io, PEER_ENCRYPTION_NONE );
if( handshake->encryptionMode == TR_ENCRYPTION_REQUIRED )
{
dbgmsg( handshake,
"peer is unencrypted, and we're disallowing that" );
return tr_handshakeDone( handshake, FALSE );
}
}
else /* encrypted or corrupt */
{
tr_peerIoSetEncryption( handshake->io, PEER_ENCRYPTION_RC4 );
if( tr_peerIoIsIncoming( handshake->io ) )
{
dbgmsg( handshake,
"I think peer is sending us an encrypted handshake..." );
setState( handshake, AWAITING_YA );
return READ_NOW;
}
tr_cryptoDecrypt( handshake->crypto, 1, &pstrlen, &pstrlen );
if( pstrlen != 19 )
{
dbgmsg( handshake,
"I think peer has sent us a corrupt handshake..." );
return tr_handshakeDone( handshake, FALSE );
}
}
evbuffer_drain( inbuf, 1 );
/* pstr (BitTorrent) */
pstr = tr_new( uint8_t, pstrlen + 1 );
tr_peerIoReadBytes( handshake->io, inbuf, pstr, pstrlen );
pstr[pstrlen] = '\0';
if( strcmp( (char*)pstr, "BitTorrent protocol" ) )
{
tr_free( pstr );
return tr_handshakeDone( handshake, FALSE );
}
tr_free( pstr );
/* reserved bytes */
tr_peerIoReadBytes( handshake->io, inbuf, reserved, sizeof( reserved ) );
/**
*** Extensions
**/
tr_peerIoEnableLTEP( handshake->io, HANDSHAKE_HAS_LTEP( reserved ) );
tr_peerIoEnableFEXT( handshake->io, HANDSHAKE_HAS_FASTEXT( reserved ) );
tr_peerIoEnableDHT( handshake->io, HANDSHAKE_HAS_DHT( reserved ) );
/* torrent hash */
tr_peerIoReadBytes( handshake->io, inbuf, hash, sizeof( hash ) );
if( tr_peerIoIsIncoming( handshake->io ) )
{
if( !tr_torrentExists( handshake->session, hash ) )
{
dbgmsg( handshake, "peer is trying to connect to us for a torrent we don't have." );
return tr_handshakeDone( handshake, FALSE );
}
else
{
assert( !tr_peerIoHasTorrentHash( handshake->io ) );
tr_peerIoSetTorrentHash( handshake->io, hash );
}
}
else /* outgoing */
{
assert( tr_peerIoHasTorrentHash( handshake->io ) );
if( memcmp( hash, tr_peerIoGetTorrentHash( handshake->io ),
SHA_DIGEST_LENGTH ) )
{
dbgmsg( handshake, "peer returned the wrong hash. wtf?" );
return tr_handshakeDone( handshake, FALSE );
}
}
/**
*** If it's an incoming message, we need to send a response handshake
**/
if( !handshake->haveSentBitTorrentHandshake )
{
uint8_t msg[HANDSHAKE_SIZE];
buildHandshakeMessage( handshake, msg );
tr_peerIoWriteBytes( handshake->io, msg, sizeof( msg ), FALSE );
handshake->haveSentBitTorrentHandshake = 1;
}
setReadState( handshake, AWAITING_PEER_ID );
return READ_NOW;
}
