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transmission/libtransmission/peer-io.c

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/*
* This file Copyright (C) 2007-2008 Charles Kerr <charles@transmissionbt.com>
*
* This file is licensed by the GPL version 2. Works owned by the
* Transmission project are granted a special exemption to clause 2(b)
* so that the bulk of its code can remain under the MIT license.
* This exemption does not extend to derived works not owned by
* the Transmission project.
*
* $Id$
*/
#include <assert.h>
#include <limits.h> /* INT_MAX */
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#ifdef WIN32
#include <winsock2.h>
#else
#include <arpa/inet.h> /* inet_ntoa */
#endif
#include <event.h>
#include "transmission.h"
#include "session.h"
#include "bandwidth.h"
#include "crypto.h"
#include "list.h"
#include "net.h"
#include "peer-io.h"
#include "platform.h" /* MAX_STACK_ARRAY_SIZE */
#include "trevent.h"
#include "utils.h"
#define MAGIC_NUMBER 206745
static size_t
getPacketOverhead( size_t d )
{
/**
* http://sd.wareonearth.com/~phil/net/overhead/
*
* TCP over Ethernet:
* Assuming no header compression (e.g. not PPP)
* Add 20 IPv4 header or 40 IPv6 header (no options)
* Add 20 TCP header
* Add 12 bytes optional TCP timestamps
* Max TCP Payload data rates over ethernet are thus:
* (1500-40)/(38+1500) = 94.9285 % IPv4, minimal headers
* (1500-52)/(38+1500) = 94.1482 % IPv4, TCP timestamps
* (1500-52)/(42+1500) = 93.9040 % 802.1q, IPv4, TCP timestamps
* (1500-60)/(38+1500) = 93.6281 % IPv6, minimal headers
* (1500-72)/(38+1500) = 92.8479 % IPv6, TCP timestamps
* (1500-72)/(42+1500) = 92.6070 % 802.1q, IPv6, ICP timestamps
*/
static const double assumed_payload_data_rate = 94.0;
return (size_t)( d * ( 100.0 / assumed_payload_data_rate ) - d );
}
/**
***
**/
#define dbgmsg( io, ... ) \
do { \
if( tr_deepLoggingIsActive( ) ) \
tr_deepLog( __FILE__, __LINE__, tr_peerIoGetAddrStr( io ), __VA_ARGS__ ); \
} while( 0 )
struct tr_datatype
{
tr_bool isPieceData;
size_t length;
struct __tr_list head;
};
/***
****
***/
static void
didWriteWrapper( tr_peerIo * io, size_t bytes_transferred )
{
while( bytes_transferred )
{
struct tr_datatype * next = __tr_list_entry( io->outbuf_datatypes.next,
struct tr_datatype, head );
const size_t payload = MIN( next->length, bytes_transferred );
const size_t overhead = getPacketOverhead( payload );
tr_bandwidthUsed( &io->bandwidth, TR_UP, payload, next->isPieceData );
if( overhead > 0 )
tr_bandwidthUsed( &io->bandwidth, TR_UP, overhead, FALSE );
if( io->didWrite )
io->didWrite( io, payload, next->isPieceData, io->userData );
bytes_transferred -= payload;
next->length -= payload;
if( !next->length ) {
__tr_list_remove( io->outbuf_datatypes.next );
tr_free( next );
}
}
}
static void
canReadWrapper( tr_peerIo * io )
{
tr_bool done = 0;
tr_bool err = 0;
tr_session * session = io->session;
dbgmsg( io, "canRead" );
tr_peerIoRef( io );
/* try to consume the input buffer */
if( io->canRead )
{
tr_globalLock( session );
while( !done && !err )
{
size_t piece = 0;
const size_t oldLen = EVBUFFER_LENGTH( io->inbuf );
const int ret = io->canRead( io, io->userData, &piece );
const size_t used = oldLen - EVBUFFER_LENGTH( io->inbuf );
assert( tr_isPeerIo( io ) );
if( piece )
tr_bandwidthUsed( &io->bandwidth, TR_DOWN, piece, TRUE );
if( used != piece )
tr_bandwidthUsed( &io->bandwidth, TR_DOWN, used - piece, FALSE );
switch( ret )
{
case READ_NOW:
if( EVBUFFER_LENGTH( io->inbuf ) )
continue;
done = 1;
break;
case READ_LATER:
done = 1;
break;
case READ_ERR:
err = 1;
break;
}
}
tr_globalUnlock( session );
}
tr_peerIoUnref( io );
}
tr_bool
tr_isPeerIo( const tr_peerIo * io )
{
return ( io != NULL )
&& ( io->magicNumber == MAGIC_NUMBER )
&& ( io->refCount > 0 )
&& ( tr_isBandwidth( &io->bandwidth ) )
&& ( tr_isAddress( &io->addr ) )
&& ( tr_isBool( io->isEncrypted ) )
&& ( tr_isBool( io->isIncoming ) )
&& ( tr_isBool( io->peerIdIsSet ) )
&& ( tr_isBool( io->extendedProtocolSupported ) )
&& ( tr_isBool( io->fastExtensionSupported ) );
}
static void
event_read_cb( int fd, short event UNUSED, void * vio )
{
int res;
int e;
tr_peerIo * io = vio;
/* Limit the input buffer to 256K, so it doesn't grow too large */
size_t howmuch;
const tr_direction dir = TR_DOWN;
const size_t max = 256 * 1024;
size_t curlen;
assert( tr_isPeerIo( io ) );
curlen = EVBUFFER_LENGTH( io->inbuf );
howmuch = curlen >= max ? 0 : max - curlen;
howmuch = tr_bandwidthClamp( &io->bandwidth, TR_DOWN, howmuch );
dbgmsg( io, "libevent says this peer is ready to read" );
/* if we don't have any bandwidth left, stop reading */
if( howmuch < 1 ) {
tr_peerIoSetEnabled( io, dir, FALSE );
return;
}
errno = 0;
res = evbuffer_read( io->inbuf, fd, howmuch );
e = errno;
if( res > 0 )
{
tr_peerIoSetEnabled( io, dir, TRUE );
/* Invoke the user callback - must always be called last */
canReadWrapper( io );
}
else
{
short what = EVBUFFER_READ;
if( res == 0 ) /* EOF */
what |= EVBUFFER_EOF;
else if( res == -1 ) {
if( e == EAGAIN || e == EINTR ) {
tr_peerIoSetEnabled( io, dir, TRUE );
return;
}
what |= EVBUFFER_ERROR;
}
dbgmsg( io, "event_read_cb got an error. res is %d, what is %hd, errno is %d (%s)", res, what, e, strerror( e ) );
if( io->gotError != NULL )
io->gotError( io, what, io->userData );
}
}
static ssize_t
tr_evbuffer_write( tr_peerIo * io, int fd, size_t howmuch )
{
int e;
ssize_t n;
struct evbuffer * buffer = io->outbuf;
howmuch = MIN( EVBUFFER_LENGTH( buffer ), howmuch );
errno = 0;
#ifdef WIN32
n = send(fd, buffer->buffer, howmuch, 0 );
#else
n = write(fd, buffer->buffer, howmuch );
#endif
e = errno;
dbgmsg( io, "wrote %zd to peer (%s)", n, (n==-1?strerror(e):"") );
if( n > 0 )
evbuffer_drain( buffer, n );
return n;
}
static void
event_write_cb( int fd, short event UNUSED, void * vio )
{
int res = 0;
int e;
short what = EVBUFFER_WRITE;
tr_peerIo * io = vio;
size_t howmuch;
const tr_direction dir = TR_UP;
assert( tr_isPeerIo( io ) );
dbgmsg( io, "libevent says this peer is ready to write" );
/* Write as much as possible, since the socket is non-blocking, write() will
* return if it can't write any more data without blocking */
howmuch = tr_bandwidthClamp( &io->bandwidth, dir, EVBUFFER_LENGTH( io->outbuf ) );
/* if we don't have any bandwidth left, stop writing */
if( howmuch < 1 ) {
tr_peerIoSetEnabled( io, dir, FALSE );
return;
}
errno = 0;
res = tr_evbuffer_write( io, fd, howmuch );
e = errno;
if (res == -1) {
#ifndef WIN32
/*todo. evbuffer uses WriteFile when WIN32 is set. WIN32 system calls do not
* *set errno. thus this error checking is not portable*/
if (e == EAGAIN || e == EINTR || e == EINPROGRESS)
goto reschedule;
/* error case */
what |= EVBUFFER_ERROR;
#else
goto reschedule;
#endif
} else if (res == 0) {
/* eof case */
what |= EVBUFFER_EOF;
}
if (res <= 0)
goto error;
if( EVBUFFER_LENGTH( io->outbuf ) )
tr_peerIoSetEnabled( io, dir, TRUE );
didWriteWrapper( io, res );
return;
reschedule:
if( EVBUFFER_LENGTH( io->outbuf ) )
tr_peerIoSetEnabled( io, dir, TRUE );
return;
error:
dbgmsg( io, "event_write_cb got an error. res is %d, what is %hd, errno is %d (%s)", res, what, e, strerror( e ) );
if( io->gotError != NULL )
io->gotError( io, what, io->userData );
}
/**
***
**/
static tr_peerIo*
tr_peerIoNew( tr_session * session,
tr_bandwidth * parent,
const tr_address * addr,
tr_port port,
const uint8_t * torrentHash,
int isIncoming,
int socket )
{
tr_peerIo * io;
if( socket >= 0 )
tr_netSetTOS( socket, session->peerSocketTOS );
io = tr_new0( tr_peerIo, 1 );
io->magicNumber = MAGIC_NUMBER;
io->refCount = 1;
io->crypto = tr_cryptoNew( torrentHash, isIncoming );
io->session = session;
io->addr = *addr;
io->port = port;
io->socket = socket;
io->isIncoming = isIncoming != 0;
io->timeCreated = time( NULL );
io->inbuf = evbuffer_new( );
io->outbuf = evbuffer_new( );
tr_bandwidthConstruct( &io->bandwidth, session, parent );
tr_bandwidthSetPeer( &io->bandwidth, io );
dbgmsg( io, "bandwidth is %p; its parent is %p", &io->bandwidth, parent );
event_set( &io->event_read, io->socket, EV_READ, event_read_cb, io );
event_set( &io->event_write, io->socket, EV_WRITE, event_write_cb, io );
__tr_list_init( &io->outbuf_datatypes );
return io;
}
tr_peerIo*
tr_peerIoNewIncoming( tr_session * session,
tr_bandwidth * parent,
const tr_address * addr,
tr_port port,
int socket )
{
assert( session );
assert( tr_isAddress( addr ) );
assert( socket >= 0 );
return tr_peerIoNew( session, parent, addr, port, NULL, 1, socket );
}
tr_peerIo*
tr_peerIoNewOutgoing( tr_session * session,
tr_bandwidth * parent,
const tr_address * addr,
tr_port port,
const uint8_t * torrentHash )
{
int socket;
assert( session );
assert( tr_isAddress( addr ) );
assert( torrentHash );
socket = tr_netOpenTCP( session, addr, port );
return socket < 0
? NULL
: tr_peerIoNew( session, parent, addr, port, torrentHash, 0, socket );
}
static void
trDatatypeFree( void * data )
{
struct tr_datatype * dt = __tr_list_entry( data, struct tr_datatype, head );
tr_free(dt);
}
static void
io_dtor( void * vio )
{
tr_peerIo * io = vio;
event_del( &io->event_read );
event_del( &io->event_write );
tr_bandwidthDestruct( &io->bandwidth );
evbuffer_free( io->outbuf );
evbuffer_free( io->inbuf );
tr_netClose( io->socket );
tr_cryptoFree( io->crypto );
__tr_list_destroy( &io->outbuf_datatypes, trDatatypeFree );
io->magicNumber = 0xDEAD;
tr_free( io );
}
static void
tr_peerIoFree( tr_peerIo * io )
{
if( io )
{
io->canRead = NULL;
io->didWrite = NULL;
io->gotError = NULL;
tr_runInEventThread( io->session, io_dtor, io );
}
}
void
tr_peerIoRef( tr_peerIo * io )
{
assert( tr_isPeerIo( io ) );
++io->refCount;
}
void
tr_peerIoUnref( tr_peerIo * io )
{
assert( tr_isPeerIo( io ) );
if( !--io->refCount )
tr_peerIoFree( io );
}
const tr_address*
tr_peerIoGetAddress( const tr_peerIo * io,
tr_port * port )
{
assert( tr_isPeerIo( io ) );
if( port )
*port = io->port;
return &io->addr;
}
const char*
tr_peerIoAddrStr( const tr_address * addr, tr_port port )
{
static char buf[512];
if( addr->type == TR_AF_INET )
tr_snprintf( buf, sizeof( buf ), "%s:%u", tr_ntop_non_ts( addr ), ntohs( port ) );
else
tr_snprintf( buf, sizeof( buf ), "[%s]:%u", tr_ntop_non_ts( addr ), ntohs( port ) );
return buf;
}
void
tr_peerIoSetIOFuncs( tr_peerIo * io,
tr_can_read_cb readcb,
tr_did_write_cb writecb,
tr_net_error_cb errcb,
void * userData )
{
io->canRead = readcb;
io->didWrite = writecb;
io->gotError = errcb;
io->userData = userData;
}
void
tr_peerIoClear( tr_peerIo * io )
{
tr_peerIoSetIOFuncs( io, NULL, NULL, NULL, NULL );
tr_peerIoSetEnabled( io, TR_UP, FALSE );
tr_peerIoSetEnabled( io, TR_DOWN, FALSE );
}
int
tr_peerIoReconnect( tr_peerIo * io )
{
assert( !tr_peerIoIsIncoming( io ) );
if( io->socket >= 0 )
tr_netClose( io->socket );
io->socket = tr_netOpenTCP( io->session, &io->addr, io->port );
if( io->socket >= 0 )
{
tr_netSetTOS( io->socket, io->session->peerSocketTOS );
return 0;
}
return -1;
}
/**
***
**/
void
tr_peerIoSetTorrentHash( tr_peerIo * io,
const uint8_t * hash )
{
assert( tr_isPeerIo( io ) );
tr_cryptoSetTorrentHash( io->crypto, hash );
}
const uint8_t*
tr_peerIoGetTorrentHash( tr_peerIo * io )
{
assert( tr_isPeerIo( io ) );
assert( io->crypto );
return tr_cryptoGetTorrentHash( io->crypto );
}
int
tr_peerIoHasTorrentHash( const tr_peerIo * io )
{
assert( tr_isPeerIo( io ) );
assert( io->crypto );
return tr_cryptoHasTorrentHash( io->crypto );
}
/**
***
**/
void
tr_peerIoSetPeersId( tr_peerIo * io,
const uint8_t * peer_id )
{
assert( tr_isPeerIo( io ) );
if( ( io->peerIdIsSet = peer_id != NULL ) )
memcpy( io->peerId, peer_id, 20 );
else
memset( io->peerId, 0, 20 );
}
/**
***
**/
void
tr_peerIoEnableFEXT( tr_peerIo * io,
tr_bool flag )
{
assert( tr_isPeerIo( io ) );
assert( tr_isBool( flag ) );
dbgmsg( io, "setting FEXT support flag to %d", (flag!=0) );
io->fastExtensionSupported = flag;
}
void
tr_peerIoEnableLTEP( tr_peerIo * io,
tr_bool flag )
{
assert( tr_isPeerIo( io ) );
assert( tr_isBool( flag ) );
dbgmsg( io, "setting LTEP support flag to %d", (flag!=0) );
io->extendedProtocolSupported = flag;
}
/**
***
**/
static size_t
getDesiredOutputBufferSize( const tr_peerIo * io, uint64_t now )
{
/* this is all kind of arbitrary, but what seems to work well is
* being large enough to hold the next 20 seconds' worth of input,
* or a few blocks, whichever is bigger.
* It's okay to tweak this as needed */
const double maxBlockSize = 16 * 1024; /* 16 KiB is from BT spec */
const double currentSpeed = tr_bandwidthGetPieceSpeed( &io->bandwidth, now, TR_UP );
const double period = 20; /* arbitrary */
const double numBlocks = 5.5; /* the 5 is arbitrary; the .5 is to leave room for messages */
return MAX( maxBlockSize*numBlocks, currentSpeed*1024*period );
}
size_t
tr_peerIoGetWriteBufferSpace( const tr_peerIo * io, uint64_t now )
{
const size_t desiredLen = getDesiredOutputBufferSize( io, now );
const size_t currentLen = EVBUFFER_LENGTH( io->outbuf );
size_t freeSpace = 0;
if( desiredLen > currentLen )
freeSpace = desiredLen - currentLen;
return freeSpace;
}
/**
***
**/
void
tr_peerIoSetEncryption( tr_peerIo * io,
int encryptionMode )
{
assert( tr_isPeerIo( io ) );
assert( encryptionMode == PEER_ENCRYPTION_NONE
|| encryptionMode == PEER_ENCRYPTION_RC4 );
io->encryptionMode = encryptionMode;
}
/**
***
**/
void
tr_peerIoWrite( tr_peerIo * io,
const void * writeme,
size_t writemeLen,
int isPieceData )
{
struct tr_datatype * datatype;
assert( tr_amInEventThread( io->session ) );
dbgmsg( io, "adding %zu bytes into io->output", writemeLen );
datatype = tr_new( struct tr_datatype, 1 );
datatype->isPieceData = isPieceData != 0;
datatype->length = writemeLen;
__tr_list_init( &datatype->head );
__tr_list_append( &io->outbuf_datatypes, &datatype->head );
evbuffer_add( io->outbuf, writeme, writemeLen );
}
void
tr_peerIoWriteBuf( tr_peerIo * io,
struct evbuffer * buf,
int isPieceData )
{
const size_t n = EVBUFFER_LENGTH( buf );
tr_peerIoWrite( io, EVBUFFER_DATA( buf ), n, isPieceData );
evbuffer_drain( buf, n );
}
/**
***
**/
void
tr_peerIoWriteBytes( tr_peerIo * io,
struct evbuffer * outbuf,
const void * bytes,
size_t byteCount )
{
uint8_t tmp[MAX_STACK_ARRAY_SIZE];
switch( io->encryptionMode )
{
case PEER_ENCRYPTION_NONE:
evbuffer_add( outbuf, bytes, byteCount );
break;
case PEER_ENCRYPTION_RC4: {
const uint8_t * walk = bytes;
evbuffer_expand( outbuf, byteCount );
while( byteCount > 0 ) {
const size_t thisPass = MIN( byteCount, sizeof( tmp ) );
tr_cryptoEncrypt( io->crypto, thisPass, walk, tmp );
evbuffer_add( outbuf, tmp, thisPass );
walk += thisPass;
byteCount -= thisPass;
}
break;
}
default:
assert( 0 );
}
}
/***
****
***/
void
tr_peerIoReadBytes( tr_peerIo * io,
struct evbuffer * inbuf,
void * bytes,
size_t byteCount )
{
assert( tr_isPeerIo( io ) );
assert( EVBUFFER_LENGTH( inbuf ) >= byteCount );
switch( io->encryptionMode )
{
case PEER_ENCRYPTION_NONE:
evbuffer_remove( inbuf, bytes, byteCount );
break;
case PEER_ENCRYPTION_RC4:
evbuffer_remove( inbuf, bytes, byteCount );
tr_cryptoDecrypt( io->crypto, byteCount, bytes, bytes );
break;
default:
assert( 0 );
}
}
void
tr_peerIoDrain( tr_peerIo * io,
struct evbuffer * inbuf,
size_t byteCount )
{
uint8_t tmp[MAX_STACK_ARRAY_SIZE];
while( byteCount > 0 )
{
const size_t thisPass = MIN( byteCount, sizeof( tmp ) );
tr_peerIoReadBytes( io, inbuf, tmp, thisPass );
byteCount -= thisPass;
}
}
/***
****
***/
static ssize_t
tr_peerIoTryRead( tr_peerIo * io, size_t howmuch )
{
ssize_t res = 0;
if(( howmuch = tr_bandwidthClamp( &io->bandwidth, TR_DOWN, howmuch )))
{
int e;
errno = 0;
res = evbuffer_read( io->inbuf, io->socket, howmuch );
e = errno;
dbgmsg( io, "read %zd from peer (%s)", res, (res==-1?strerror(e):"") );
if( EVBUFFER_LENGTH( io->inbuf ) )
canReadWrapper( io );
if( ( res <= 0 ) && ( io->gotError ) && ( e != EAGAIN ) && ( e != EINTR ) && ( e != EINPROGRESS ) )
{
short what = EVBUFFER_READ | EVBUFFER_ERROR;
if( res == 0 )
what |= EVBUFFER_EOF;
dbgmsg( io, "tr_peerIoTryRead got an error. res is %zd, what is %hd, errno is %d (%s)", res, what, e, strerror( e ) );
io->gotError( io, what, io->userData );
}
}
return res;
}
static ssize_t
tr_peerIoTryWrite( tr_peerIo * io, size_t howmuch )
{
ssize_t n = 0;
if(( howmuch = tr_bandwidthClamp( &io->bandwidth, TR_UP, howmuch )))
{
int e;
errno = 0;
n = tr_evbuffer_write( io, io->socket, howmuch );
e = errno;
if( n > 0 )
didWriteWrapper( io, n );
if( ( n < 0 ) && ( io->gotError ) && ( e != EPIPE ) && ( e != EAGAIN ) && ( e != EINTR ) && ( e != EINPROGRESS ) )
{
const short what = EVBUFFER_WRITE | EVBUFFER_ERROR;
dbgmsg( io, "tr_peerIoTryWrite got an error. res is %zd, what is %hd, errno is %d (%s)", n, what, e, strerror( e ) );
io->gotError( io, what, io->userData );
}
}
return n;
}
ssize_t
tr_peerIoFlush( tr_peerIo * io, tr_direction dir, size_t limit )
{
ssize_t bytesUsed;
assert( tr_isPeerIo( io ) );
assert( tr_isDirection( dir ) );
if( dir == TR_DOWN )
bytesUsed = tr_peerIoTryRead( io, limit );
else
bytesUsed = tr_peerIoTryWrite( io, limit );
dbgmsg( io, "flushing peer-io, direction %d, limit %zu, bytesUsed %zd", (int)dir, limit, bytesUsed );
return bytesUsed;
}
/***
****
****/
static void
event_enable( tr_peerIo * io, short event )
{
assert( tr_isPeerIo( io ) );
if( event & EV_READ )
event_add( &io->event_read, NULL );
if( event & EV_WRITE )
event_add( &io->event_write, NULL );
}
static void
event_disable( struct tr_peerIo * io, short event )
{
assert( tr_isPeerIo( io ) );
if( event & EV_READ )
event_del( &io->event_read );
if( event & EV_WRITE )
event_del( &io->event_write );
}
void
tr_peerIoSetEnabled( tr_peerIo * io,
tr_direction dir,
tr_bool isEnabled )
{
short event;
assert( tr_isPeerIo( io ) );
assert( tr_isDirection( dir ) );
event = dir == TR_UP ? EV_WRITE : EV_READ;
if( isEnabled )
event_enable( io, event );
else
event_disable( io, event );
}
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