forked from flanksource/karina
/
dns.go
178 lines (150 loc) · 4.54 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
package dns
import (
"fmt"
"strings"
"time"
"github.com/flanksource/commons/logger"
"github.com/miekg/dns"
)
var tsigAlgs = map[string]string{
"hmac-md5": dns.HmacMD5,
"hmac-sha1": dns.HmacSHA1,
"hmac-sha256": dns.HmacSHA256,
"hmac-sha512": dns.HmacSHA512,
}
type Client interface {
Append(domain string, records ...string) error
Get(domain string) ([]string, error)
Update(domain string, records ...string) error
Delete(domain string, records ...string) error
}
type DynamicDNSClient struct {
logger.Logger
KeyName string
Zone string
Nameserver string
Key string
Algorithm string
Insecure bool
}
func (client DynamicDNSClient) Append(domain string, records ...string) error {
domain = subdomain(domain, client.Zone)
client.Debugf("Appending %s.%s %s", domain, client.Zone, records)
m := new(dns.Msg)
m.SetUpdate(client.Zone + ".")
for _, record := range records {
rr, err := newRR(domain, client.Zone, 60, "A", record)
if err != nil {
return fmt.Errorf("append: failed to get new RR: %v", err)
}
m.Insert([]dns.RR{*rr})
}
return client.sendMessage(client.Zone, m)
}
func (client DynamicDNSClient) Get(domain string) ([]string, error) {
m := new(dns.Msg)
m.SetAxfr(domain)
if !client.Insecure {
m.SetTsig(client.KeyName, tsigAlgs[client.Algorithm], 300, time.Now().Unix())
}
t := new(dns.Transfer)
if !client.Insecure {
t.TsigSecret = map[string]string{client.KeyName: client.Key}
}
env, err := t.In(m, client.Nameserver)
if err != nil {
return nil, fmt.Errorf("failed to fetch records via AXFR: %v", err)
}
var records []string
for e := range env {
if e.Error != nil {
if e.Error == dns.ErrSoa {
return nil, fmt.Errorf("AXFR error: unexpected response received from the server")
}
return nil, fmt.Errorf("AXFR error: %v", e.Error)
}
for _, rr := range e.RR {
switch rr.Header().Rrtype {
case dns.TypeCNAME:
records = append(records, rr.(*dns.CNAME).Target)
case dns.TypeA:
records = append(records, rr.(*dns.A).A.String())
case dns.TypeAAAA:
records = append(records, rr.(*dns.AAAA).AAAA.String())
case dns.TypeTXT:
records = append(records, rr.(*dns.TXT).String())
default:
continue // Unhandled record type
}
}
}
return records, nil
}
func (client DynamicDNSClient) Update(domain string, records ...string) error {
domain = subdomain(domain, client.Zone)
client.Debugf("Updating %s.%s %s", domain, client.Zone, records)
m := new(dns.Msg)
m.SetUpdate(client.Zone + ".")
rr, err := newRR(domain, client.Zone, 0, "ANY", "")
if err != nil {
return fmt.Errorf("update: failed to get new RR: %v", err)
}
m.RemoveRRset([]dns.RR{*rr})
for _, record := range records {
rr, err := newRR(domain, client.Zone, 60, "A", record)
if err != nil {
return fmt.Errorf("update: failed to get new RR: %v", err)
}
m.Insert([]dns.RR{*rr})
}
return client.sendMessage(client.Zone, m)
}
func (client DynamicDNSClient) Delete(domain string, records ...string) error {
domain = subdomain(domain, client.Zone)
client.Debugf("Removing %s.%s %s", domain, client.Zone, records)
m := new(dns.Msg)
m.SetUpdate(client.Zone + ".")
for _, record := range records {
if record == "*" {
rr, err := newRR(domain, client.Zone, 0, "ANY", "")
if err != nil {
return fmt.Errorf("delete: failed to get new RR: %v", err)
}
m.RemoveRRset([]dns.RR{*rr})
} else {
rr, err := newRR(domain, client.Zone, 0, "A", record)
if err != nil {
return fmt.Errorf("delete: failed to get new RR: %v", err)
}
m.Remove([]dns.RR{*rr})
}
}
return client.sendMessage(client.Zone, m)
}
// nolint: unparam
func (client DynamicDNSClient) sendMessage(zone string, msg *dns.Msg) error {
c := new(dns.Client)
c.SingleInflight = true
c.Net = "tcp"
c.TsigSecret = map[string]string{client.KeyName: client.Key}
msg.SetTsig(client.KeyName, tsigAlgs[client.Algorithm], 300, time.Now().Unix())
resp, _, err := c.Exchange(msg, client.Nameserver)
if err != nil {
return fmt.Errorf("error in dns.Client.Exchange: %s", err)
}
if resp != nil && resp.Rcode != dns.RcodeSuccess {
return fmt.Errorf("bad return code: %s", dns.RcodeToString[resp.Rcode])
}
return nil
}
func newRR(domain string, zone string, ttl int, resourceType string, record string) (*dns.RR, error) {
RR := strings.Trim(fmt.Sprintf("%s.%s %d %s %s", domain, zone, ttl, resourceType, record), " ")
rr, err := dns.NewRR(RR)
if err != nil {
return nil, fmt.Errorf("newRR failed: %v", err)
}
return &rr, nil
}
func subdomain(domain, zone string) string {
return strings.ReplaceAll(domain, "."+zone, "")
}