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fw-daemon/socks_server_chain.go

132 lines
3.0 KiB

package main
import (
"io"
"net"
"os"
"sync"
"github.com/subgraph/fw-daemon/socks5"
)
type SocksChainConfig struct {
TargetSocksNet string
TargetSocksAddr string
ListenSocksNet string
ListenSocksAddr string
}
type session struct {
cfg *SocksChainConfig
clientConn net.Conn
upstreamConn net.Conn
req *socks5.Request
bndAddr *socks5.Address
optData []byte
}
// InitSocksListener initializes the SOCKS 5 server and starts
// accepting connections.
func InitSocksListener(cfg *SocksChainConfig, wg *sync.WaitGroup) {
ln, err := net.Listen(cfg.ListenSocksNet, cfg.ListenSocksAddr)
if err != nil {
log.Error("ERR/socks: Failed to listen on the socks address: %v", err)
os.Exit(1)
}
wg.Add(1)
go socksAcceptLoop(cfg, ln, wg)
}
func socksAcceptLoop(cfg *SocksChainConfig, ln net.Listener, wg *sync.WaitGroup) error {
defer wg.Done()
defer ln.Close()
for {
conn, err := ln.Accept()
if err != nil {
if e, ok := err.(net.Error); ok && !e.Temporary() {
log.Info("ERR/socks: Failed to Accept(): %v", err)
return err
}
continue
}
s := &session{cfg: cfg, clientConn: conn}
go s.sessionWorker()
}
}
func (s *session) sessionWorker() {
defer s.clientConn.Close()
clientAddr := s.clientConn.RemoteAddr()
log.Info("INFO/socks: New connection from: %v", clientAddr)
// Do the SOCKS handshake with the client, and read the command.
var err error
if s.req, err = socks5.Handshake(s.clientConn); err != nil {
log.Info("ERR/socks: Failed SOCKS5 handshake: %v", err)
return
}
switch s.req.Cmd {
case socks5.CommandTorResolve, socks5.CommandTorResolvePTR:
err = s.dispatchTorSOCKS()
// If we reach here, the request has been dispatched and completed.
if err == nil {
// Successfully even, send the response back with the address.
s.req.ReplyAddr(socks5.ReplySucceeded, s.bndAddr)
}
return
case socks5.CommandConnect:
default:
// Should *NEVER* happen, validated as part of handshake.
log.Info("BUG/socks: Unsupported SOCKS command: 0x%02x", s.req.Cmd)
s.req.Reply(socks5.ReplyCommandNotSupported)
return
}
err = s.dispatchTorSOCKS()
if err != nil {
return
}
s.req.Reply(socks5.ReplySucceeded)
defer s.upstreamConn.Close()
if s.optData != nil {
if _, err = s.upstreamConn.Write(s.optData); err != nil {
log.Info("ERR/socks: Failed writing OptData: %v", err)
return
}
s.optData = nil
}
// A upstream connection has been established, push data back and forth
// till the session is done.
var wg sync.WaitGroup
wg.Add(2)
copyLoop := func(dst, src net.Conn) {
defer wg.Done()
defer dst.Close()
io.Copy(dst, src)
}
go copyLoop(s.upstreamConn, s.clientConn)
go copyLoop(s.clientConn, s.upstreamConn)
wg.Wait()
log.Info("INFO/socks: Closed SOCKS connection from: %v", clientAddr)
}
func (s *session) dispatchTorSOCKS() (err error) {
s.upstreamConn, s.bndAddr, err = socks5.Redispatch(s.cfg.TargetSocksNet, s.cfg.TargetSocksAddr, s.req)
if err != nil {
s.req.Reply(socks5.ErrorToReplyCode(err))
}
return
}