59 lines
1.4 KiB
Go
59 lines
1.4 KiB
Go
package main
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import (
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"fmt"
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"log"
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"net"
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"os/exec"
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"strings"
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)
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func requiresRRUpdate(entry *RRConfig, addr net.IP) bool {
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// TODO: use custom resolver to query authoritive nameserver instead of
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// local resolver
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addrs, err := net.LookupIP(entry.Hostname)
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if err != nil {
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log.Printf("dns lookup failed: %s", err)
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// enforce update, it's better than not trying at all
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return true
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}
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// check if the current ip matches
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for _, ip := range addrs {
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if ip.Equal(addr) {
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// the ip seems to be still up-to-date -> no update required
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return false
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}
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}
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return true
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}
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func updateRR(entry *RRConfig, addr net.IP) error {
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query := generateQuery(entry, addr)
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return executeQuery(query)
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}
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func generateQuery(entry *RRConfig, addr net.IP) string {
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var q strings.Builder
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fmt.Fprintf(&q, "key %s\n", entry.Tsigkey)
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fmt.Fprintf(&q, "server %s\n", entry.Nameserver)
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fmt.Fprintf(&q, "zone %s\n", entry.Zonename)
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// TODO: check if addr is ipv4 or ipv6 (-> update A or AAAA)
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fmt.Fprintf(&q, "add %s. %d A %s\n", entry.Hostname, entry.Ttl, addr.String())
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fmt.Fprintf(&q, "send\n")
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return q.String()
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}
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func executeQuery(query string) error {
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cmd := exec.Command("knsupdate", "-v")
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cmd.Stdin = strings.NewReader(query)
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output, err := cmd.CombinedOutput()
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// TODO: is outputting stdout+stderr on failure even necessary?
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if err != nil {
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log.Printf("executeQuery failed: %s", output)
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}
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return err
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}
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