/
udpme.go
76 lines (65 loc) · 1.35 KB
/
udpme.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
package fastforward
import (
"context"
"net"
"time"
"github.com/IrineSistiana/mosdns/v3/dispatcher/pkg/dnsutils"
"github.com/miekg/dns"
)
type udpmeUpstream struct {
addr string
trusted bool
}
func newUDPME(addr string, trusted bool) *udpmeUpstream {
if _, _, err := net.SplitHostPort(addr); err != nil {
addr = net.JoinHostPort(addr, "53")
}
return &udpmeUpstream{addr: addr, trusted: trusted}
}
func (u *udpmeUpstream) Address() string {
return u.addr
}
func (u *udpmeUpstream) Trusted() bool {
return u.trusted
}
func (u *udpmeUpstream) Exchange(ctx context.Context, m *dns.Msg) (*dns.Msg, error) {
ddl, ok := ctx.Deadline()
if !ok {
ddl = time.Now().Add(time.Second * 3)
}
if m.IsEdns0() != nil {
return u.exchangeOPTM(m, ddl)
}
mc := m.Copy()
mc.SetEdns0(512, false)
r, err := u.exchangeOPTM(mc, ddl)
if err != nil {
return nil, err
}
dnsutils.RemoveEDNS0(r)
return r, nil
}
func (u *udpmeUpstream) exchangeOPTM(m *dns.Msg, ddl time.Time) (*dns.Msg, error) {
c, err := dns.Dial("udp", u.addr)
if err != nil {
return nil, err
}
defer c.Close()
c.SetDeadline(ddl)
if opt := m.IsEdns0(); opt != nil {
c.UDPSize = opt.UDPSize()
}
if err := c.WriteMsg(m); err != nil {
return nil, err
}
for {
r, err := c.ReadMsg()
if err != nil {
return nil, err
}
if r.IsEdns0() == nil {
continue
}
return r, nil
}
}