forked from eycorsican/go-tun2socks
-
Notifications
You must be signed in to change notification settings - Fork 0
/
udp.go
289 lines (255 loc) · 6.79 KB
/
udp.go
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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
package socks
import (
"errors"
"fmt"
"io"
"net"
"strconv"
"sync"
"time"
"github.com/eycorsican/go-tun2socks/common/dns"
"github.com/eycorsican/go-tun2socks/common/log"
"github.com/eycorsican/go-tun2socks/core"
)
type udpHandler struct {
sync.Mutex
proxyHost string
proxyPort uint16
udpConns map[core.UDPConn]net.PacketConn
tcpConns map[core.UDPConn]net.Conn
remoteAddrs map[core.UDPConn]*net.UDPAddr // UDP relay server addresses
dnsCache dns.DnsCache
fakeDns dns.FakeDns
timeout time.Duration
}
func NewUDPHandler(proxyHost string, proxyPort uint16, timeout time.Duration, dnsCache dns.DnsCache, fakeDns dns.FakeDns) core.UDPConnHandler {
return &udpHandler{
proxyHost: proxyHost,
proxyPort: proxyPort,
udpConns: make(map[core.UDPConn]net.PacketConn, 8),
tcpConns: make(map[core.UDPConn]net.Conn, 8),
remoteAddrs: make(map[core.UDPConn]*net.UDPAddr, 8),
dnsCache: dnsCache,
fakeDns: fakeDns,
timeout: timeout,
}
}
func (h *udpHandler) handleTCP(conn core.UDPConn, c net.Conn) {
buf := core.NewBytes(core.BufSize)
defer core.FreeBytes(buf)
for {
c.SetDeadline(time.Time{})
_, err := c.Read(buf)
if err == io.EOF {
log.Warnf("UDP associate to %v closed by remote", c.RemoteAddr())
h.Close(conn)
return
} else if err != nil {
h.Close(conn)
return
}
}
}
func (h *udpHandler) fetchUDPInput(conn core.UDPConn, input net.PacketConn) {
buf := core.NewBytes(core.BufSize)
defer func() {
h.Close(conn)
core.FreeBytes(buf)
}()
for {
input.SetDeadline(time.Now().Add(h.timeout))
n, _, err := input.ReadFrom(buf)
if err != nil {
// log.Printf("read remote failed: %v", err)
return
}
addr := SplitAddr(buf[3:])
resolvedAddr, err := net.ResolveUDPAddr("udp", addr.String())
if err != nil {
return
}
_, err = conn.WriteFrom(buf[int(3+len(addr)):n], resolvedAddr)
if err != nil {
log.Warnf("write local failed: %v", err)
return
}
if h.dnsCache != nil {
_, port, err := net.SplitHostPort(addr.String())
if err != nil {
panic("impossible error")
}
if port == strconv.Itoa(dns.COMMON_DNS_PORT) {
h.dnsCache.Store(buf[int(3+len(addr)):n])
return // DNS response
}
}
}
}
func (h *udpHandler) Connect(conn core.UDPConn, target net.Addr) error {
if target == nil {
return h.connectInternal(conn, "")
}
// Replace with a domain name if target address IP is a fake IP.
host, port, err := net.SplitHostPort(target.String())
if err != nil {
log.Errorf("error when split host port %v", err)
}
var targetHost string = host
if h.fakeDns != nil {
_, port, err := net.SplitHostPort(target.String())
if err != nil {
panic("impossible error")
}
if port == strconv.Itoa(dns.COMMON_DNS_PORT) {
return nil // skip dns
}
if ip := net.ParseIP(host); ip != nil {
if h.fakeDns.IsFakeIP(ip) {
targetHost = h.fakeDns.QueryDomain(ip)
}
}
}
dest := fmt.Sprintf("%s:%s", targetHost, port)
return h.connectInternal(conn, dest)
}
func (h *udpHandler) connectInternal(conn core.UDPConn, dest string) error {
c, err := net.DialTimeout("tcp", core.ParseTCPAddr(h.proxyHost, h.proxyPort).String(), 4*time.Second)
if err != nil {
return err
}
c.SetDeadline(time.Now().Add(4 * time.Second))
// send VER, NMETHODS, METHODS
c.Write([]byte{5, 1, 0})
buf := make([]byte, MaxAddrLen)
// read VER METHOD
if _, err := io.ReadFull(c, buf[:2]); err != nil {
return err
}
if len(dest) != 0 {
targetAddr := ParseAddr(dest)
// write VER CMD RSV ATYP DST.ADDR DST.PORT
c.Write(append([]byte{5, socks5UDPAssociate, 0}, targetAddr...))
} else {
c.Write(append([]byte{5, socks5UDPAssociate, 0}, []byte{1, 0, 0, 0, 0, 0, 0}...))
}
// read VER REP RSV ATYP BND.ADDR BND.PORT
if _, err := io.ReadFull(c, buf[:3]); err != nil {
return err
}
rep := buf[1]
if rep != 0 {
return errors.New("SOCKS handshake failed")
}
remoteAddr, err := readAddr(c, buf)
if err != nil {
return err
}
resolvedRemoteAddr, err := net.ResolveUDPAddr("udp", remoteAddr.String())
if err != nil {
return errors.New("failed to resolve remote address")
}
go h.handleTCP(conn, c)
pc, err := net.ListenPacket("udp", "")
if err != nil {
return err
}
h.Lock()
h.tcpConns[conn] = c
h.udpConns[conn] = pc
h.remoteAddrs[conn] = resolvedRemoteAddr
h.Unlock()
go h.fetchUDPInput(conn, pc)
if len(dest) != 0 {
log.Access("proxy", "udp", conn.LocalAddr().String(), dest)
}
return nil
}
func (h *udpHandler) ReceiveTo(conn core.UDPConn, data []byte, addr net.Addr) error {
h.Lock()
pc, ok1 := h.udpConns[conn]
remoteAddr, ok2 := h.remoteAddrs[conn]
h.Unlock()
if h.fakeDns != nil {
_, port, err := net.SplitHostPort(addr.String())
if err != nil {
panic("impossible error")
}
if port == strconv.Itoa(dns.COMMON_DNS_PORT) {
resp, err := h.fakeDns.GenerateFakeResponse(data)
if err != nil {
// FIXME This will block the lwip thread, need to optimize.
if err := h.connectInternal(conn, addr.String()); err != nil {
return fmt.Errorf("failed to connect to %v:%v", addr.Network(), addr.String())
}
h.Lock()
pc, ok1 = h.udpConns[conn]
remoteAddr, ok2 = h.remoteAddrs[conn]
h.Unlock()
} else {
_, err = conn.WriteFrom(resp, addr)
if err != nil {
return errors.New(fmt.Sprintf("write dns answer failed: %v", err))
}
h.Close(conn)
return nil
}
}
}
if h.dnsCache != nil {
_, port, err := net.SplitHostPort(addr.String())
if err != nil {
panic("impossible error")
}
if port == strconv.Itoa(dns.COMMON_DNS_PORT) {
if answer := h.dnsCache.Query(data); answer != nil {
_, err = conn.WriteFrom(answer, addr)
if err != nil {
return errors.New(fmt.Sprintf("write dns answer failed: %v", err))
}
h.Close(conn)
return nil
}
}
}
if ok1 && ok2 {
// Replace with a domain name if target address IP is a fake IP.
host, port, err := net.SplitHostPort(addr.String())
if err != nil {
log.Errorf("error when split host port %v", err)
}
var targetHost string = host
if h.fakeDns != nil {
if ip := net.ParseIP(host); ip != nil {
if h.fakeDns.IsFakeIP(ip) {
targetHost = h.fakeDns.QueryDomain(ip)
}
}
}
dest := fmt.Sprintf("%s:%s", targetHost, port)
buf := append([]byte{0, 0, 0}, ParseAddr(dest)...)
buf = append(buf, data[:]...)
_, err = pc.WriteTo(buf, remoteAddr)
if err != nil {
h.Close(conn)
return errors.New(fmt.Sprintf("write remote failed: %v", err))
}
return nil
} else {
h.Close(conn)
return errors.New(fmt.Sprintf("proxy connection %v->%v does not exists", conn.LocalAddr(), addr))
}
}
func (h *udpHandler) Close(conn core.UDPConn) {
conn.Close()
h.Lock()
defer h.Unlock()
if c, ok := h.tcpConns[conn]; ok {
c.Close()
delete(h.tcpConns, conn)
}
if pc, ok := h.udpConns[conn]; ok {
pc.Close()
delete(h.udpConns, conn)
}
delete(h.remoteAddrs, conn)
}