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
|
// Copyright 2017 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 tcpproxy
import (
"bufio"
"bytes"
"context"
"crypto/tls"
"io"
"net"
)
// AddSNIRoute appends a route to the ipPort listener that routes to
// dest if the incoming TLS SNI server name is sni. If it doesn't
// match, rule processing continues for any additional routes on
// ipPort.
//
// The ipPort is any valid net.Listen TCP address.
func (p *Proxy) AddSNIRoute(ipPort, sni string, dest Target) {
p.AddSNIMatchRoute(ipPort, equals(sni), dest)
}
// AddSNIMatchRoute appends a route to the ipPort listener that routes
// to dest if the incoming TLS SNI server name is accepted by
// matcher. If it doesn't match, rule processing continues for any
// additional routes on ipPort.
//
// The ipPort is any valid net.Listen TCP address.
func (p *Proxy) AddSNIMatchRoute(ipPort string, matcher Matcher, dest Target) {
p.addRoute(ipPort, sniMatch{matcher: matcher, target: dest})
}
// SNITargetFunc is the func callback used by Proxy.AddSNIRouteFunc.
type SNITargetFunc func(ctx context.Context, sniName string) (t Target, ok bool)
// AddSNIRouteFunc adds a route to ipPort that matches an SNI request and calls
// fn to map its nap to a target.
func (p *Proxy) AddSNIRouteFunc(ipPort string, fn SNITargetFunc) {
p.addRoute(ipPort, sniMatch{targetFunc: fn})
}
type sniMatch struct {
matcher Matcher
target Target
// Alternatively, if targetFunc is non-nil, it's used instead:
targetFunc SNITargetFunc
}
func (m sniMatch) match(br *bufio.Reader) (Target, string) {
sni := clientHelloServerName(br)
if sni == "" {
return nil, ""
}
if m.targetFunc != nil {
if t, ok := m.targetFunc(context.TODO(), sni); ok {
return t, sni
}
return nil, ""
}
if m.matcher(context.TODO(), sni) {
return m.target, sni
}
return nil, ""
}
// clientHelloServerName returns the SNI server name inside the TLS ClientHello,
// without consuming any bytes from br.
// On any error, the empty string is returned.
func clientHelloServerName(br *bufio.Reader) (sni string) {
const recordHeaderLen = 5
hdr, err := br.Peek(recordHeaderLen)
if err != nil {
return ""
}
const recordTypeHandshake = 0x16
if hdr[0] != recordTypeHandshake {
return "" // Not TLS.
}
recLen := int(hdr[3])<<8 | int(hdr[4]) // ignoring version in hdr[1:3]
helloBytes, err := br.Peek(recordHeaderLen + recLen)
if err != nil {
return ""
}
tls.Server(sniSniffConn{r: bytes.NewReader(helloBytes)}, &tls.Config{
GetConfigForClient: func(hello *tls.ClientHelloInfo) (*tls.Config, error) {
sni = hello.ServerName
return nil, nil
},
}).Handshake()
return
}
// sniSniffConn is a net.Conn that reads from r, fails on Writes,
// and crashes otherwise.
type sniSniffConn struct {
r io.Reader
net.Conn // nil; crash on any unexpected use
}
func (c sniSniffConn) Read(p []byte) (int, error) { return c.r.Read(p) }
func (sniSniffConn) Write(p []byte) (int, error) { return 0, io.EOF }
|
