-
Notifications
You must be signed in to change notification settings - Fork 0
/
dns.go
305 lines (258 loc) · 6.2 KB
/
dns.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
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
// +build !confonly
package dns
import (
"context"
"io"
"sync"
"golang.org/x/net/dns/dnsmessage"
"v2ray.com/core"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/net"
dns_proto "v2ray.com/core/common/protocol/dns"
"v2ray.com/core/common/session"
"v2ray.com/core/common/task"
"v2ray.com/core/features/dns"
"v2ray.com/core/transport"
"v2ray.com/core/transport/internet"
)
func init() {
common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
h := new(Handler)
if err := core.RequireFeatures(ctx, func(dnsClient dns.Client) error {
return h.Init(config.(*Config), dnsClient)
}); err != nil {
return nil, err
}
return h, nil
}))
}
type ownLinkVerifier interface {
IsOwnLink(ctx context.Context) bool
}
type Handler struct {
ipv4Lookup dns.IPv4Lookup
ipv6Lookup dns.IPv6Lookup
ownLinkVerifier ownLinkVerifier
}
func (h *Handler) Init(config *Config, dnsClient dns.Client) error {
ipv4lookup, ok := dnsClient.(dns.IPv4Lookup)
if !ok {
return newError("dns.Client doesn't implement IPv4Lookup")
}
h.ipv4Lookup = ipv4lookup
ipv6lookup, ok := dnsClient.(dns.IPv6Lookup)
if !ok {
return newError("dns.Client doesn't implement IPv6Lookup")
}
h.ipv6Lookup = ipv6lookup
if v, ok := dnsClient.(ownLinkVerifier); ok {
h.ownLinkVerifier = v
}
return nil
}
func (h *Handler) isOwnLink(ctx context.Context) bool {
return h.ownLinkVerifier != nil && h.ownLinkVerifier.IsOwnLink(ctx)
}
func parseIPQuery(b []byte) (r bool, domain string, id uint16, qType dnsmessage.Type) {
var parser dnsmessage.Parser
header, err := parser.Start(b)
if err != nil {
newError("parser start").Base(err).WriteToLog()
return
}
id = header.ID
q, err := parser.Question()
if err != nil {
newError("question").Base(err).WriteToLog()
return
}
qType = q.Type
if qType != dnsmessage.TypeA && qType != dnsmessage.TypeAAAA {
return
}
domain = q.Name.String()
r = true
return
}
// Process implements proxy.Outbound.
func (h *Handler) Process(ctx context.Context, link *transport.Link, d internet.Dialer) error {
outbound := session.OutboundFromContext(ctx)
if outbound == nil || !outbound.Target.IsValid() {
return newError("invalid outbound")
}
dest := outbound.Target
conn := &outboundConn{
dialer: func() (internet.Connection, error) {
return d.Dial(ctx, dest)
},
connReady: make(chan struct{}, 1),
}
var reader dns_proto.MessageReader
var writer dns_proto.MessageWriter
if dest.Network == net.Network_TCP {
reader = dns_proto.NewTCPReader(link.Reader)
writer = &dns_proto.TCPWriter{
Writer: link.Writer,
}
} else {
reader = &dns_proto.UDPReader{
Reader: link.Reader,
}
writer = &dns_proto.UDPWriter{
Writer: link.Writer,
}
}
var connReader dns_proto.MessageReader
var connWriter dns_proto.MessageWriter
if dest.Network == net.Network_TCP {
connReader = dns_proto.NewTCPReader(buf.NewReader(conn))
connWriter = &dns_proto.TCPWriter{
Writer: buf.NewWriter(conn),
}
} else {
connReader = &dns_proto.UDPReader{
Reader: buf.NewPacketReader(conn),
}
connWriter = &dns_proto.UDPWriter{
Writer: buf.NewWriter(conn),
}
}
request := func() error {
defer conn.Close()
for {
b, err := reader.ReadMessage()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if !h.isOwnLink(ctx) {
isIPQuery, domain, id, qType := parseIPQuery(b.Bytes())
if isIPQuery {
go h.handleIPQuery(id, qType, domain, writer)
continue
}
}
if err := connWriter.WriteMessage(b); err != nil {
return err
}
}
}
response := func() error {
for {
b, err := connReader.ReadMessage()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if err := writer.WriteMessage(b); err != nil {
return err
}
}
}
if err := task.Run(ctx, request, response); err != nil {
return newError("connection ends").Base(err)
}
return nil
}
func (h *Handler) handleIPQuery(id uint16, qType dnsmessage.Type, domain string, writer dns_proto.MessageWriter) {
var ips []net.IP
var err error
switch qType {
case dnsmessage.TypeA:
ips, err = h.ipv4Lookup.LookupIPv4(domain)
case dnsmessage.TypeAAAA:
ips, err = h.ipv6Lookup.LookupIPv6(domain)
}
if err != nil {
newError("ip query").Base(err).WriteToLog()
return
}
if len(ips) == 0 {
return
}
b := buf.New()
rawBytes := b.Extend(buf.Size)
builder := dnsmessage.NewBuilder(rawBytes[:0], dnsmessage.Header{
ID: id,
RCode: dnsmessage.RCodeSuccess,
Response: true,
})
common.Must(builder.StartAnswers())
rHeader := dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName(domain), Class: dnsmessage.ClassINET, TTL: 600}
for _, ip := range ips {
if len(ip) == net.IPv4len {
var r dnsmessage.AResource
copy(r.A[:], ip)
common.Must(builder.AResource(rHeader, r))
} else {
var r dnsmessage.AAAAResource
copy(r.AAAA[:], ip)
common.Must(builder.AAAAResource(rHeader, r))
}
}
msgBytes, err := builder.Finish()
if err != nil {
newError("pack message").Base(err).WriteToLog()
b.Release()
return
}
b.Resize(0, int32(len(msgBytes)))
if err := writer.WriteMessage(b); err != nil {
newError("write IP answer").Base(err).WriteToLog()
}
}
type outboundConn struct {
access sync.Mutex
dialer func() (internet.Connection, error)
conn net.Conn
connReady chan struct{}
}
func (c *outboundConn) dial() error {
conn, err := c.dialer()
if err != nil {
return err
}
c.conn = conn
c.connReady <- struct{}{}
return nil
}
func (c *outboundConn) Write(b []byte) (int, error) {
c.access.Lock()
if c.conn == nil {
if err := c.dial(); err != nil {
c.access.Unlock()
newError("failed to dial outbound connection").Base(err).AtWarning().WriteToLog()
return len(b), nil
}
}
c.access.Unlock()
return c.conn.Write(b)
}
func (c *outboundConn) Read(b []byte) (int, error) {
var conn net.Conn
c.access.Lock()
conn = c.conn
c.access.Unlock()
if conn == nil {
_, open := <-c.connReady
if !open {
return 0, io.EOF
}
conn = c.conn
}
return conn.Read(b)
}
func (c *outboundConn) Close() error {
c.access.Lock()
close(c.connReady)
if c.conn != nil {
c.conn.Close()
}
c.access.Unlock()
return nil
}