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transmission/libtransmission/tr-dht.c

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/*
* Copyright (c) 2009-2010 by Juliusz Chroboczek
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* $Id$
*
*/
/* ansi */
#include <errno.h>
#include <stdio.h>
#include <string.h> /* memcpy(), memset(), memchr(), strlen() */
#include <stdlib.h> /* atoi() */
/* posix */
#include <signal.h> /* sig_atomic_t */
#include <sys/time.h>
#include <unistd.h> /* close() */
#ifdef WIN32
#include <inttypes.h>
#define _WIN32_WINNT 0x0501 /* freeaddrinfo(),getaddrinfo(),getnameinfo() */
#include <ws2tcpip.h>
#else
#include <sys/types.h>
#include <sys/socket.h> /* socket(), bind() */
#include <netdb.h>
#include <netinet/in.h> /* sockaddr_in */
#endif
/* third party */
#include <event2/event.h>
#include <dht/dht.h>
/* libT */
#include "transmission.h"
#include "bencode.h"
#include "crypto.h"
#include "net.h"
#include "peer-mgr.h" /* tr_peerMgrCompactToPex() */
#include "platform.h" /* tr_threadNew() */
#include "session.h"
#include "torrent.h" /* tr_torrentFindFromHash() */
#include "tr-dht.h"
#include "trevent.h" /* tr_runInEventThread() */
#include "utils.h"
static struct event *dht_timer = NULL;
static unsigned char myid[20];
static tr_session *session = NULL;
static void timer_callback(int s, short type, void *ignore);
struct bootstrap_closure {
tr_session *session;
uint8_t *nodes;
uint8_t *nodes6;
size_t len, len6;
};
static int
bootstrap_done( tr_session *session, int af )
{
int status;
if(af == 0)
return
bootstrap_done(session, AF_INET) &&
bootstrap_done(session, AF_INET6);
status = tr_dhtStatus(session, af, NULL);
return status == TR_DHT_STOPPED || status >= TR_DHT_FIREWALLED;
}
static void
nap( int roughly_sec )
{
const int roughly_msec = roughly_sec * 1000;
const int msec = roughly_msec/2 + tr_cryptoWeakRandInt(roughly_msec);
tr_wait_msec( msec );
}
static int
bootstrap_af(tr_session *session)
{
if( bootstrap_done(session, AF_INET6) )
return AF_INET;
else if ( bootstrap_done(session, AF_INET) )
return AF_INET6;
else
return 0;
}
static void
bootstrap_from_name( const char *name, tr_port port, int af )
{
struct addrinfo hints, *info, *infop;
char pp[10];
int rc;
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_DGRAM;
hints.ai_family = af;
/* No, just passing p + 1 to gai won't work. */
tr_snprintf(pp, sizeof(pp), "%d", (int)port);
rc = getaddrinfo(name, pp, &hints, &info);
if(rc != 0) {
tr_nerr("DHT", "%s:%s: %s", name, pp, gai_strerror(rc));
return;
}
infop = info;
while(infop) {
dht_ping_node(infop->ai_addr, infop->ai_addrlen);
nap(15);
if(bootstrap_done(session, af))
break;
infop = infop->ai_next;
}
freeaddrinfo(info);
}
static void
dht_bootstrap(void *closure)
{
struct bootstrap_closure *cl = closure;
int i;
int num = cl->len / 6, num6 = cl->len6 / 18;
if(session != cl->session)
return;
if(cl->len > 0)
tr_ninf( "DHT", "Bootstrapping from %d nodes", num );
if(cl->len6 > 0)
tr_ninf( "DHT", "Bootstrapping from %d IPv6 nodes", num6 );
for(i = 0; i < MAX(num, num6); i++) {
if( i < num && !bootstrap_done(cl->session, AF_INET) ) {
tr_port port;
struct tr_address addr;
memset(&addr, 0, sizeof(addr));
addr.type = TR_AF_INET;
memcpy(&addr.addr.addr4, &cl->nodes[i * 6], 4);
memcpy(&port, &cl->nodes[i * 6 + 4], 2);
port = ntohs(port);
tr_dhtAddNode(cl->session, &addr, port, 1);
}
if( i < num6 && !bootstrap_done(cl->session, AF_INET6) ) {
tr_port port;
struct tr_address addr;
memset(&addr, 0, sizeof(addr));
addr.type = TR_AF_INET6;
memcpy(&addr.addr.addr6, &cl->nodes6[i * 18], 16);
memcpy(&port, &cl->nodes6[i * 18 + 16], 2);
port = ntohs(port);
tr_dhtAddNode(cl->session, &addr, port, 1);
}
/* Our DHT code is able to take up to 9 nodes in a row without
dropping any. After that, it takes some time to split buckets.
So ping the first 8 nodes quickly, then slow down. */
if(i < 8)
nap(2);
else
nap(15);
if(bootstrap_done( session, 0 ))
break;
}
if(!bootstrap_done(cl->session, 0)) {
char *bootstrap_file;
FILE *f = NULL;
bootstrap_file =
tr_buildPath(cl->session->configDir, "dht.bootstrap", NULL);
if(bootstrap_file)
f = fopen(bootstrap_file, "rb");
if(f != NULL) {
tr_ninf("DHT", "Attempting manual bootstrap");
for(;;) {
char buf[201];
char *p;
int port = 0;
p = fgets(buf, 200, f);
if( p == NULL )
break;
p = memchr(buf, ' ', strlen(buf));
if(p != NULL)
port = atoi(p + 1);
if(p == NULL || port <= 0 || port >= 0x10000) {
tr_nerr("DHT", "Couldn't parse %s", buf);
continue;
}
*p = '\0';
bootstrap_from_name( buf, port, bootstrap_af(session) );
if(bootstrap_done(cl->session, 0))
break;
}
}
tr_free( bootstrap_file );
}
if(!bootstrap_done(cl->session, 0)) {
for(i = 0; i < 6; i++) {
/* We don't want to abuse our bootstrap nodes, so be very
slow. The initial wait is to give other nodes a chance
to contact us before we attempt to contact a bootstrap
node, for example because we've just been restarted. */
nap(40);
if(bootstrap_done(cl->session, 0))
break;
if(i == 0)
tr_ninf("DHT",
"Attempting bootstrap from dht.transmissionbt.com");
bootstrap_from_name( "dht.transmissionbt.com", 6881,
bootstrap_af(session) );
}
}
if( cl->nodes )
tr_free( cl->nodes );
if( cl->nodes6 )
tr_free( cl->nodes6 );
tr_free( closure );
tr_ndbg( "DHT", "Finished bootstrapping" );
}
int
tr_dhtInit(tr_session *ss)
{
tr_benc benc;
int rc;
bool have_id = false;
char * dat_file;
uint8_t * nodes = NULL, * nodes6 = NULL;
const uint8_t * raw;
size_t len, len6;
struct bootstrap_closure * cl;
if( session ) /* already initialized */
return -1;
tr_ndbg( "DHT", "Initializing DHT" );
if( getenv( "TR_DHT_VERBOSE" ) != NULL )
dht_debug = stderr;
dat_file = tr_buildPath( ss->configDir, "dht.dat", NULL );
rc = tr_bencLoadFile( &benc, TR_FMT_BENC, dat_file );
tr_free( dat_file );
if(rc == 0) {
have_id = tr_bencDictFindRaw(&benc, "id", &raw, &len);
if( have_id && len==20 )
memcpy( myid, raw, len );
if( ss->udp_socket >= 0 &&
tr_bencDictFindRaw( &benc, "nodes", &raw, &len ) && !(len%6) ) {
nodes = tr_memdup( raw, len );
}
if( ss->udp6_socket > 0 &&
tr_bencDictFindRaw( &benc, "nodes6", &raw, &len6 ) && !(len6%18) ) {
nodes6 = tr_memdup( raw, len6 );
}
tr_bencFree( &benc );
}
if(nodes == NULL)
len = 0;
if(nodes6 == NULL)
len6 = 0;
if( have_id )
tr_ninf( "DHT", "Reusing old id" );
else {
/* Note that DHT ids need to be distributed uniformly,
* so it should be something truly random. */
tr_ninf( "DHT", "Generating new id" );
tr_cryptoRandBuf( myid, 20 );
}
rc = dht_init( ss->udp_socket, ss->udp6_socket, myid, NULL );
if( rc < 0 )
goto fail;
session = ss;
cl = tr_new( struct bootstrap_closure, 1 );
cl->session = session;
cl->nodes = nodes;
cl->nodes6 = nodes6;
cl->len = len;
cl->len6 = len6;
tr_threadNew( dht_bootstrap, cl );
dht_timer = evtimer_new( session->event_base, timer_callback, session );
tr_timerAdd( dht_timer, 0, tr_cryptoWeakRandInt( 1000000 ) );
tr_ndbg( "DHT", "DHT initialized" );
return 1;
fail:
tr_ndbg( "DHT", "DHT initialization failed (errno = %d)", errno );
session = NULL;
return -1;
}
void
tr_dhtUninit(tr_session *ss)
{
if(session != ss)
return;
tr_ndbg( "DHT", "Uninitializing DHT" );
event_free( dht_timer );
dht_timer = NULL;
/* Since we only save known good nodes, avoid erasing older data if we
don't know enough nodes. */
if(tr_dhtStatus(ss, AF_INET, NULL) < TR_DHT_FIREWALLED)
tr_ninf( "DHT", "Not saving nodes, DHT not ready" );
else {
tr_benc benc;
struct sockaddr_in sins[300];
struct sockaddr_in6 sins6[300];
char compact[300 * 6], compact6[300 * 18];
char *dat_file;
int i, j, num = 300, num6 = 300;
int n = dht_get_nodes(sins, &num, sins6, &num6);
tr_ninf( "DHT", "Saving %d (%d + %d) nodes", n, num, num6 );
j = 0;
for( i=0; i<num; ++i ) {
memcpy( compact + j, &sins[i].sin_addr, 4 );
memcpy( compact + j + 4, &sins[i].sin_port, 2 );
j += 6;
}
j = 0;
for( i=0; i<num6; ++i ) {
memcpy( compact6 + j, &sins6[i].sin6_addr, 16 );
memcpy( compact6 + j + 16, &sins6[i].sin6_port, 2 );
j += 18;
}
tr_bencInitDict( &benc, 3 );
tr_bencDictAddRaw( &benc, "id", myid, 20 );
if(num > 0)
tr_bencDictAddRaw( &benc, "nodes", compact, num * 6 );
if(num6 > 0)
tr_bencDictAddRaw( &benc, "nodes6", compact6, num6 * 18 );
dat_file = tr_buildPath( ss->configDir, "dht.dat", NULL );
tr_bencToFile( &benc, TR_FMT_BENC, dat_file );
tr_bencFree( &benc );
tr_free( dat_file );
}
dht_uninit();
tr_ndbg("DHT", "Done uninitializing DHT");
session = NULL;
}
bool
tr_dhtEnabled( const tr_session * ss )
{
return ss && ( ss == session );
}
struct getstatus_closure
{
int af;
sig_atomic_t status;
sig_atomic_t count;
};
static void
getstatus( void * cl )
{
struct getstatus_closure * closure = cl;
int good, dubious, incoming;
dht_nodes( closure->af, &good, &dubious, NULL, &incoming );
closure->count = good + dubious;
if( good < 4 || good + dubious <= 8 )
closure->status = TR_DHT_BROKEN;
else if( good < 40 )
closure->status = TR_DHT_POOR;
else if( incoming < 8 )
closure->status = TR_DHT_FIREWALLED;
else
closure->status = TR_DHT_GOOD;
}
int
tr_dhtStatus( tr_session * session, int af, int * nodes_return )
{
struct getstatus_closure closure = { af, -1, -1 };
if( !tr_dhtEnabled( session ) ||
(af == AF_INET && session->udp_socket < 0) ||
(af == AF_INET6 && session->udp6_socket < 0) ) {
if( nodes_return )
*nodes_return = 0;
return TR_DHT_STOPPED;
}
tr_runInEventThread( session, getstatus, &closure );
while( closure.status < 0 )
tr_wait_msec( 50 /*msec*/ );
if( nodes_return )
*nodes_return = closure.count;
return closure.status;
}
tr_port
tr_dhtPort( tr_session *ss )
{
return tr_dhtEnabled( ss ) ? ss->udp_port : 0;
}
int
tr_dhtAddNode( tr_session * ss,
const tr_address * address,
tr_port port,
bool bootstrap )
{
int af = address->type == TR_AF_INET ? AF_INET : AF_INET6;
if( !tr_dhtEnabled( ss ) )
return 0;
/* Since we don't want to abuse our bootstrap nodes,
* we don't ping them if the DHT is in a good state. */
if(bootstrap) {
if(tr_dhtStatus(ss, af, NULL) >= TR_DHT_FIREWALLED)
return 0;
}
if( address->type == TR_AF_INET ) {
struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
memcpy(&sin.sin_addr, &address->addr.addr4, 4);
sin.sin_port = htons(port);
dht_ping_node((struct sockaddr*)&sin, sizeof(sin));
return 1;
} else if( address->type == TR_AF_INET6 ) {
struct sockaddr_in6 sin6;
memset(&sin6, 0, sizeof(sin6));
sin6.sin6_family = AF_INET6;
memcpy(&sin6.sin6_addr, &address->addr.addr6, 16);
sin6.sin6_port = htons(port);
dht_ping_node((struct sockaddr*)&sin6, sizeof(sin6));
return 1;
}
return 0;
}
const char *
tr_dhtPrintableStatus(int status)
{
switch(status) {
case TR_DHT_STOPPED: return "stopped";
case TR_DHT_BROKEN: return "broken";
case TR_DHT_POOR: return "poor";
case TR_DHT_FIREWALLED: return "firewalled";
case TR_DHT_GOOD: return "good";
default: return "???";
}
}
static void
callback( void *ignore UNUSED, int event,
unsigned char *info_hash, void *data, size_t data_len )
{
if( event == DHT_EVENT_VALUES || event == DHT_EVENT_VALUES6 ) {
tr_torrent *tor;
tr_sessionLock( session );
tor = tr_torrentFindFromHash( session, info_hash );
if( tor && tr_torrentAllowsDHT( tor ))
{
size_t i, n;
tr_pex * pex;
if( event == DHT_EVENT_VALUES )
pex = tr_peerMgrCompactToPex(data, data_len, NULL, 0, &n);
else
pex = tr_peerMgrCompact6ToPex(data, data_len, NULL, 0, &n);
for( i=0; i<n; ++i )
tr_peerMgrAddPex( tor, TR_PEER_FROM_DHT, pex+i, -1 );
tr_free(pex);
tr_tordbg(tor, "Learned %d%s peers from DHT",
(int)n,
event == DHT_EVENT_VALUES6 ? " IPv6" : "");
}
tr_sessionUnlock( session );
} else if( event == DHT_EVENT_SEARCH_DONE ||
event == DHT_EVENT_SEARCH_DONE6) {
tr_torrent * tor = tr_torrentFindFromHash( session, info_hash );
if( tor ) {
if( event == DHT_EVENT_SEARCH_DONE ) {
tr_torinf(tor, "DHT announce done");
tor->dhtAnnounceInProgress = 0;
} else {
tr_torinf(tor, "IPv6 DHT announce done");
tor->dhtAnnounce6InProgress = 0;
}
}
}
}
static int
tr_dhtAnnounce(tr_torrent *tor, int af, bool announce)
{
int rc, status, numnodes, ret = 0;
if( !tr_torrentAllowsDHT( tor ) )
return -1;
status = tr_dhtStatus( tor->session, af, &numnodes );
if( status == TR_DHT_STOPPED ) {
/* Let the caller believe everything is all right. */
return 1;
}
if(status >= TR_DHT_POOR ) {
rc = dht_search( tor->info.hash,
announce ? tr_sessionGetPeerPort(session) : 0,
af, callback, NULL);
if( rc >= 1 ) {
tr_torinf(tor, "Starting%s DHT announce (%s, %d nodes)",
af == AF_INET6 ? " IPv6" : "",
tr_dhtPrintableStatus(status), numnodes);
if(af == AF_INET)
tor->dhtAnnounceInProgress = true;
else
tor->dhtAnnounce6InProgress = true;
ret = 1;
} else {
tr_torerr(tor, "%sDHT announce failed (%s, %d nodes): %s",
af == AF_INET6 ? "IPv6 " : "",
tr_dhtPrintableStatus(status), numnodes,
tr_strerror( errno ) );
}
} else {
tr_tordbg(tor, "%sDHT not ready (%s, %d nodes)",
af == AF_INET6 ? "IPv6 " : "",
tr_dhtPrintableStatus(status), numnodes);
}
return ret;
}
void
tr_dhtUpkeep( tr_session * session )
{
tr_torrent * tor = NULL;
const time_t now = tr_time( );
while(( tor = tr_torrentNext( session, tor )))
{
if( !tor->isRunning || !tr_torrentAllowsDHT( tor ) )
continue;
if( tor->dhtAnnounceAt <= now )
{
const int rc = tr_dhtAnnounce(tor, AF_INET, 1);
tor->dhtAnnounceAt = now + ((rc == 0)
? 5 + tr_cryptoWeakRandInt( 5 )
: 25 * 60 + tr_cryptoWeakRandInt( 3*60 ));
}
if( tor->dhtAnnounce6At <= now )
{
const int rc = tr_dhtAnnounce(tor, AF_INET6, 1);
tor->dhtAnnounce6At = now + ((rc == 0)
? 5 + tr_cryptoWeakRandInt( 5 )
: 25 * 60 + tr_cryptoWeakRandInt( 3*60 ));
}
}
}
void
tr_dhtCallback(unsigned char *buf, int buflen,
struct sockaddr *from, socklen_t fromlen,
void *sv )
{
time_t tosleep;
int rc;
assert(tr_isSession(sv));
if(sv != session)
return;
rc = dht_periodic( buf, buflen, from, fromlen,
&tosleep, callback, NULL);
if(rc < 0) {
if(errno == EINTR) {
tosleep = 0;
} else {
tr_nerr( "DHT", "dht_periodic failed: %s", tr_strerror( errno ) );
if(errno == EINVAL || errno == EFAULT)
abort();
tosleep = 1;
}
}
/* Being slightly late is fine,
and has the added benefit of adding some jitter. */
tr_timerAdd( dht_timer, tosleep, tr_cryptoWeakRandInt( 1000000 ) );
}
static void
timer_callback(int s UNUSED, short type UNUSED, void *session )
{
tr_dhtCallback(NULL, 0, NULL, 0, session);
}
void
dht_hash(void *hash_return, int hash_size,
const void *v1, int len1,
const void *v2, int len2,
const void *v3, int len3)
{
unsigned char sha1[SHA_DIGEST_LENGTH];
tr_sha1( sha1, v1, len1, v2, len2, v3, len3, NULL );
memset( hash_return, 0, hash_size );
memcpy( hash_return, sha1, MIN( hash_size, SHA_DIGEST_LENGTH ) );
}
int
dht_random_bytes( void * buf, size_t size )
{
tr_cryptoRandBuf( buf, size );
return size;
}
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