1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
// Copyright 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"flag"
"fmt"
"io"
"log"
"net"
"sync"
"time"
)
var (
cfgFile = flag.String("conf", "", "configuration file")
listen = flag.String("listen", ":443", "listening port")
helloTimeout = flag.Duration("hello-timeout", 3*time.Second, "how long to wait for the TLS ClientHello")
)
func main() {
flag.Parse()
p := &Proxy{}
if err := p.Config.ReadFile(*cfgFile); err != nil {
log.Fatalf("Failed to read config %q: %s", *cfgFile, err)
}
log.Fatalf("%s", p.ListenAndServe(*listen))
}
// Proxy routes connections to backends based on a Config.
type Proxy struct {
Config Config
l net.Listener
}
// Serve accepts connections from l and routes them according to TLS SNI.
func (p *Proxy) Serve(l net.Listener) error {
for {
c, err := l.Accept()
if err != nil {
return fmt.Errorf("accept new conn: %s", err)
}
conn := &Conn{
TCPConn: c.(*net.TCPConn),
config: &p.Config,
}
go conn.proxy()
}
}
// ListenAndServe creates a listener on addr calls Serve on it.
func (p *Proxy) ListenAndServe(addr string) error {
l, err := net.Listen("tcp", addr)
if err != nil {
return fmt.Errorf("create listener: %s", err)
}
return p.Serve(l)
}
// A Conn handles the TLS proxying of one user connection.
type Conn struct {
*net.TCPConn
config *Config
tlsMinor int
hostname string
backend string
backendConn *net.TCPConn
}
func (c *Conn) logf(msg string, args ...interface{}) {
msg = fmt.Sprintf(msg, args...)
log.Printf("%s <> %s: %s", c.RemoteAddr(), c.LocalAddr(), msg)
}
func (c *Conn) abort(alert byte, msg string, args ...interface{}) {
c.logf(msg, args...)
alertMsg := []byte{21, 3, byte(c.tlsMinor), 0, 2, 2, alert}
if err := c.SetWriteDeadline(time.Now().Add(*helloTimeout)); err != nil {
c.logf("error while setting write deadline during abort: %s", err)
// Do NOT send the alert if we can't set a write deadline,
// that could result in leaking a connection for an extended
// period.
return
}
if _, err := c.Write(alertMsg); err != nil {
c.logf("error while sending alert: %s", err)
}
}
func (c *Conn) internalError(msg string, args ...interface{}) { c.abort(80, msg, args...) }
func (c *Conn) sniFailed(msg string, args ...interface{}) { c.abort(112, msg, args...) }
func (c *Conn) proxy() {
defer c.Close()
if err := c.SetReadDeadline(time.Now().Add(*helloTimeout)); err != nil {
c.internalError("Setting read deadline for ClientHello: %s", err)
return
}
var (
err error
handshakeBuf bytes.Buffer
)
c.hostname, c.tlsMinor, err = extractSNI(io.TeeReader(c, &handshakeBuf))
if err != nil {
c.internalError("Extracting SNI: %s", err)
return
}
c.logf("extracted SNI %s", c.hostname)
if err = c.SetReadDeadline(time.Time{}); err != nil {
c.internalError("Clearing read deadline for ClientHello: %s", err)
return
}
c.backend = c.config.Match(c.hostname)
if c.backend == "" {
c.sniFailed("no backend found for %q", c.hostname)
return
}
c.logf("routing %q to %q", c.hostname, c.backend)
backend, err := net.DialTimeout("tcp", c.backend, 10*time.Second)
if err != nil {
c.internalError("failed to dial backend %q for %q: %s", c.backend, c.hostname, err)
return
}
defer backend.Close()
c.backendConn = backend.(*net.TCPConn)
// Replay the piece of the handshake we had to read to do the
// routing, then blindly proxy any other bytes.
if _, err = io.Copy(c.backendConn, &handshakeBuf); err != nil {
c.internalError("failed to replay handshake to %q: %s", c.backend, err)
return
}
var wg sync.WaitGroup
wg.Add(2)
go proxy(&wg, c.TCPConn, c.backendConn)
go proxy(&wg, c.backendConn, c.TCPConn)
wg.Wait()
}
func proxy(wg *sync.WaitGroup, a, b net.Conn) {
defer wg.Done()
atcp, btcp := a.(*net.TCPConn), b.(*net.TCPConn)
if _, err := io.Copy(atcp, btcp); err != nil {
log.Printf("%s<>%s -> %s<>%s: %s", atcp.RemoteAddr(), atcp.LocalAddr(), btcp.LocalAddr(), btcp.RemoteAddr(), err)
}
btcp.CloseWrite()
atcp.CloseRead()
}
|
