forked from TrueCloudLab/lego
85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
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package acme
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import (
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"fmt"
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"github.com/miekg/dns"
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"time"
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)
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// DNSProviderRFC2136 is an implementation of the DNSProvider interface that
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// uses dynamic DNS updates (RFC 2136) to create TXT records on a nameserver.
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type DNSProviderRFC2136 struct {
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nameserver string
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zone string
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tsigKey string
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tsigSecret string
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}
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// NewDNSProviderRFC2136 returns a new DNSProviderRFC2136 instance.
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// To disable TSIG authentication 'tsigKey' and 'tsigSecret' must be set to the empty string.
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// 'nameserver' must be a network address in the the form "host:port". 'zone' must be the fully
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// qualified name of the zone.
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func NewDNSProviderRFC2136(nameserver, zone, tsigKey, tsigSecret string) (*DNSProviderRFC2136, error) {
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d := &DNSProviderRFC2136{
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nameserver: nameserver,
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zone: zone,
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}
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if len(tsigKey) > 0 && len(tsigSecret) > 0 {
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d.tsigKey = tsigKey
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d.tsigSecret = tsigSecret
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}
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return d, nil
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}
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// CreateTXTRecord creates a TXT record using the specified parameters
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func (r *DNSProviderRFC2136) CreateTXTRecord(fqdn, value string, ttl int) error {
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return r.changeRecord("INSERT", fqdn, value, ttl)
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}
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// RemoveTXTRecord removes the TXT record matching the specified parameters
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func (r *DNSProviderRFC2136) RemoveTXTRecord(fqdn, value string, ttl int) error {
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return r.changeRecord("REMOVE", fqdn, value, ttl)
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}
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func (r *DNSProviderRFC2136) changeRecord(action, fqdn, value string, ttl int) error {
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// Create RR
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rr := new(dns.TXT)
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rr.Hdr = dns.RR_Header{Name: fqdn, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: uint32(ttl)}
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rr.Txt = []string{value}
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rrs := make([]dns.RR, 1)
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rrs[0] = rr
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// Create dynamic update packet
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m := new(dns.Msg)
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m.SetUpdate(dns.Fqdn(r.zone))
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switch action {
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case "INSERT":
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m.Insert(rrs)
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case "REMOVE":
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m.Remove(rrs)
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default:
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return fmt.Errorf("Unexpected action: %s", action)
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}
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// Setup client
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c := new(dns.Client)
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c.SingleInflight = true
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// TSIG authentication / msg signing
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if len(r.tsigKey) > 0 && len(r.tsigSecret) > 0 {
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m.SetTsig(dns.Fqdn(r.tsigKey), dns.HmacMD5, 300, time.Now().Unix())
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c.TsigSecret = map[string]string{dns.Fqdn(r.tsigKey): r.tsigSecret}
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}
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// Send the query
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reply, _, err := c.Exchange(m, r.nameserver)
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if err != nil {
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return fmt.Errorf("DNS update failed: %v", err)
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}
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if reply != nil && reply.Rcode != dns.RcodeSuccess {
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return fmt.Errorf("DNS update failed. Server replied: %s", dns.RcodeToString[reply.Rcode])
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}
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return nil
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}
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