Cloak/internal/client/connector.go

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2020-04-06 12:07:16 +00:00
package client
import (
"encoding/binary"
"net"
"sync"
"sync/atomic"
"syscall"
"time"
mux "github.com/cbeuw/Cloak/internal/multiplex"
"github.com/cbeuw/Cloak/internal/util"
log "github.com/sirupsen/logrus"
)
type remoteConnConfig struct {
NumConn int
KeepAlive time.Duration
Protector func(string, string, syscall.RawConn) error
RemoteAddr string
Transport Transport
}
func MakeSession(connConfig *remoteConnConfig, authInfo *authInfo, isAdmin bool) *mux.Session {
log.Info("Attempting to start a new session")
if !isAdmin {
// sessionID is usergenerated. There shouldn't be a security concern because the scope of
// sessionID is limited to its UID.
quad := make([]byte, 4)
util.CryptoRandRead(quad)
authInfo.SessionId = binary.BigEndian.Uint32(quad)
} else {
authInfo.SessionId = 0
}
d := net.Dialer{Control: connConfig.Protector, KeepAlive: connConfig.KeepAlive}
connsCh := make(chan net.Conn, connConfig.NumConn)
var _sessionKey atomic.Value
var wg sync.WaitGroup
for i := 0; i < connConfig.NumConn; i++ {
wg.Add(1)
go func() {
makeconn:
remoteConn, err := d.Dial("tcp", connConfig.RemoteAddr)
if err != nil {
log.Errorf("Failed to establish new connections to remote: %v", err)
// TODO increase the interval if failed multiple times
time.Sleep(time.Second * 3)
goto makeconn
}
var sk []byte
remoteConn, sk, err = connConfig.Transport.PrepareConnection(authInfo, remoteConn)
if err != nil {
remoteConn.Close()
log.Errorf("Failed to prepare connection to remote: %v", err)
time.Sleep(time.Second * 3)
goto makeconn
}
_sessionKey.Store(sk)
connsCh <- remoteConn
wg.Done()
}()
}
wg.Wait()
log.Debug("All underlying connections established")
sessionKey := _sessionKey.Load().([]byte)
obfuscator, err := mux.GenerateObfs(authInfo.EncryptionMethod, sessionKey, connConfig.Transport.HasRecordLayer())
if err != nil {
log.Fatal(err)
}
seshConfig := &mux.SessionConfig{
Obfuscator: obfuscator,
Valve: nil,
UnitRead: connConfig.Transport.UnitReadFunc(),
Unordered: authInfo.Unordered,
}
sesh := mux.MakeSession(authInfo.SessionId, seshConfig)
for i := 0; i < connConfig.NumConn; i++ {
conn := <-connsCh
sesh.AddConnection(conn)
}
log.Infof("Session %v established", authInfo.SessionId)
return sesh
}