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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package socks
import (
"context"
"errors"
"io"
"net"
"strconv"
"time"
)
var (
noDeadline = time.Time{}
aLongTimeAgo = time.Unix(1, 0)
)
func (d *Dialer) connect(ctx context.Context, c net.Conn, address string) (_ net.Addr, ctxErr error) {
host, port, err := splitHostPort(address)
if err != nil {
return nil, err
}
if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() {
c.SetDeadline(deadline)
defer c.SetDeadline(noDeadline)
}
if ctx != context.Background() {
errCh := make(chan error, 1)
done := make(chan struct{})
defer func() {
close(done)
if ctxErr == nil {
ctxErr = <-errCh
}
}()
go func() {
select {
case <-ctx.Done():
c.SetDeadline(aLongTimeAgo)
errCh <- ctx.Err()
case <-done:
errCh <- nil
}
}()
}
b := make([]byte, 0, 6+len(host)) // the size here is just an estimate
b = append(b, Version5)
if len(d.AuthMethods) == 0 || d.Authenticate == nil {
b = append(b, 1, byte(AuthMethodNotRequired))
} else {
ams := d.AuthMethods
if len(ams) > 255 {
return nil, errors.New("too many authentication methods")
}
b = append(b, byte(len(ams)))
for _, am := range ams {
b = append(b, byte(am))
}
}
if _, ctxErr = c.Write(b); ctxErr != nil {
return
}
if _, ctxErr = io.ReadFull(c, b[:2]); ctxErr != nil {
return
}
if b[0] != Version5 {
return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0])))
}
am := AuthMethod(b[1])
if am == AuthMethodNoAcceptableMethods {
return nil, errors.New("no acceptable authentication methods")
}
if d.Authenticate != nil {
if ctxErr = d.Authenticate(ctx, c, am); ctxErr != nil {
return
}
}
b = b[:0]
b = append(b, Version5, byte(d.cmd), 0)
if ip := net.ParseIP(host); ip != nil {
if ip4 := ip.To4(); ip4 != nil {
b = append(b, AddrTypeIPv4)
b = append(b, ip4...)
} else if ip6 := ip.To16(); ip6 != nil {
b = append(b, AddrTypeIPv6)
b = append(b, ip6...)
} else {
return nil, errors.New("unknown address type")
}
} else {
if len(host) > 255 {
return nil, errors.New("FQDN too long")
}
b = append(b, AddrTypeFQDN)
b = append(b, byte(len(host)))
b = append(b, host...)
}
b = append(b, byte(port>>8), byte(port))
if _, ctxErr = c.Write(b); ctxErr != nil {
return
}
if _, ctxErr = io.ReadFull(c, b[:4]); ctxErr != nil {
return
}
if b[0] != Version5 {
return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0])))
}
if cmdErr := Reply(b[1]); cmdErr != StatusSucceeded {
return nil, errors.New("unknown error " + cmdErr.String())
}
if b[2] != 0 {
return nil, errors.New("non-zero reserved field")
}
l := 2
var a Addr
switch b[3] {
case AddrTypeIPv4:
l += net.IPv4len
a.IP = make(net.IP, net.IPv4len)
case AddrTypeIPv6:
l += net.IPv6len
a.IP = make(net.IP, net.IPv6len)
case AddrTypeFQDN:
if _, err := io.ReadFull(c, b[:1]); err != nil {
return nil, err
}
l += int(b[0])
default:
return nil, errors.New("unknown address type " + strconv.Itoa(int(b[3])))
}
if cap(b) < l {
b = make([]byte, l)
} else {
b = b[:l]
}
if _, ctxErr = io.ReadFull(c, b); ctxErr != nil {
return
}
if a.IP != nil {
copy(a.IP, b)
} else {
a.Name = string(b[:len(b)-2])
}
a.Port = int(b[len(b)-2])<<8 | int(b[len(b)-1])
return &a, nil
}
func splitHostPort(address string) (string, int, error) {
host, port, err := net.SplitHostPort(address)
if err != nil {
return "", 0, err
}
portnum, err := strconv.Atoi(port)
if err != nil {
return "", 0, err
}
if 1 > portnum || portnum > 0xffff {
return "", 0, errors.New("port number out of range " + port)
}
return host, portnum, nil
}
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