archives/snowflake
2
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git synced 2025-10-13 11:11:30 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Create new smux session for each SOCKS connection

Browse source 
Each SOCKS connection has its own set of snowflakes and broker poll
loop. Since the session manager was tied to a single set of snowflakes,
this resulted in a bug where RedialPacketConn would sometimes try to
pull snowflakes from a previously melted pool. The fix is to maintain
separate smux sessions for each SOCKS connection, tied to its own
snowflake pool.
This commit is contained in:
Cecylia Bocovich 2020-11-23 14:02:54 -05:00
parent 5efcde5187
commit 114df695ce
1 changed files with 6 additions and 51 deletions
Download patch file Download diff file Expand all files Collapse all files

57
client/lib/snowflake.go
View file

@ -6,7 +6,6 @@ import (
"io"
"log"
"net"
"sync"
"time"
"git.torproject.org/pluggable-transports/snowflake.git/common/turbotunnel"
@ -92,54 +91,6 @@ func newSession(snowflakes SnowflakeCollector) (net.PacketConn, *smux.Session, e
return pconn, sess, err
}
// sessionManager_ maintains a single global smux.Session that is shared among
// incoming SOCKS connections.
type sessionManager_ struct {
mutex sync.Mutex
sess *smux.Session
}
// Get creates and returns a new global smux.Session if none exists yet. If one
// already exists, it returns the existing one. It monitors the returned session
// and if it ever fails, sets things up so the next call to Get will create a
// new session.
func (manager *sessionManager_) Get(snowflakes SnowflakeCollector) (*smux.Session, error) {
manager.mutex.Lock()
defer manager.mutex.Unlock()
if manager.sess == nil {
log.Printf("starting a new session")
pconn, sess, err := newSession(snowflakes)
if err != nil {
return nil, err
}
manager.sess = sess
go func() {
// If the session dies, set it to be recreated.
for {
<-time.After(5 * time.Second)
if sess.IsClosed() {
break
}
}
log.Printf("discarding finished session")
// Close the underlying to force any ongoing WebRTC
// connection to close as well, and relinquish the
// SnowflakeCollector.
pconn.Close()
manager.mutex.Lock()
manager.sess = nil
manager.mutex.Unlock()
}()
} else {
log.Printf("reusing the existing session")
}
return manager.sess, nil
}
var sessionManager = sessionManager_{}
// Given an accepted SOCKS connection, establish a WebRTC connection to the
// remote peer and exchange traffic.
func Handler(socks net.Conn, tongue Tongue) error {
@ -155,8 +106,9 @@ func Handler(socks net.Conn, tongue Tongue) error {
log.Printf("---- Handler: begin collecting snowflakes ---")
go connectLoop(snowflakes)
// Return the global smux.Session.
sess, err := sessionManager.Get(snowflakes)
// Create a new smux session
log.Printf("---- Handler: starting a new session ---")
pconn, sess, err := newSession(snowflakes)
if err != nil {
return err
}
@ -174,6 +126,9 @@ func Handler(socks net.Conn, tongue Tongue) error {
log.Printf("---- Handler: closed stream %v ---", stream.ID())
snowflakes.End()
log.Printf("---- Handler: end collecting snowflakes ---")
pconn.Close()
sess.Close()
log.Printf("---- Handler: discarding finished session ---")
return nil
}