Initial commit

updater/updater.go

@@ -0,0 +1,173 @@
+package updater
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/cloudflare/cloudflare-go"
+)
+
+// DefaultIPCheckURL is the default URL used to figure out the public IP.
+const DefaultIPCheckURL = "http://whatismyip.akamai.com/"
+
+// DefaultInterval is the default number of seconds to wait before each update.
+const DefaultInterval = 30
+
+// New creates a new DynDNS instance.
+func New(email string, apiKey string) *Updater {
+	api, err := cloudflare.New(apiKey, email)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	return &Updater{
+		API:        api,
+		IPCheckURL: DefaultIPCheckURL,
+		Interval:   DefaultInterval,
+	}
+}
+
+// Updater deals with updating the IP address for a DNS record
+type Updater struct {
+	API        *cloudflare.API
+	IPCheckURL string
+	Interval   int
+}
+
+// Update performs a the full update sequence.
+func (u *Updater) Update(host string) error {
+	fmt.Printf("Looking up record for %s...\n", host)
+	record, err := u.RecordByHost(host)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Found %s (%s)\n", record.Name, record.ID)
+
+	fmt.Printf("Starting IP check (repeats every %d seconds)\n", u.Interval)
+	for {
+		record, err = u.UpdateRecord(record)
+		if err != nil {
+			fmt.Printf("ERROR: %s\n", err.Error())
+			fmt.Printf("Retrying in %d seconds...", u.Interval)
+		}
+
+		time.Sleep(time.Duration(u.Interval) * time.Second)
+	}
+}
+
+// UpdateRecord updates a cloudflare.DNSRecord.
+func (u *Updater) UpdateRecord(record *cloudflare.DNSRecord) (*cloudflare.DNSRecord, error) {
+	currentIP, err := u.WhatIsMyIP()
+	if err != nil {
+		return nil, err
+	}
+
+	record, err = u.Record(record.ZoneID, record.ID)
+	if err != nil {
+		return nil, err
+	}
+
+	if currentIP != record.Content {
+		fmt.Printf(
+			"Updating %s to %s (was %s)\n",
+			record.Name, currentIP, record.Content,
+		)
+		record.Content = currentIP
+		err = u.API.UpdateDNSRecord(record.ZoneID, record.ID, *record)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return record, nil
+}
+
+// Record fetches a cloudflare.DNSRecord from the given Zone and Record IDs.
+func (u *Updater) Record(zoneID string, recordID string) (*cloudflare.DNSRecord, error) {
+	record, err := u.API.DNSRecord(zoneID, recordID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &record, nil
+}
+
+// RecordByHost fetches a cloudflare.DNSRecord from the host given.
+func (u *Updater) RecordByHost(host string) (*cloudflare.DNSRecord, error) {
+	zoneID, err := u.ZoneID(host)
+	if err != nil {
+		return nil, err
+	}
+
+	recordID, err := u.RecordID(host, zoneID)
+	if err != nil {
+		return nil, err
+	}
+
+	record, err := u.Record(zoneID, recordID)
+	if err != nil {
+		return nil, err
+	}
+
+	return record, nil
+}
+
+// WhatIsMyIP fetches the public IP via http://whatismyip.akamai.com/
+func (u *Updater) WhatIsMyIP() (string, error) {
+	client := &http.Client{Timeout: time.Second * 10}
+	resp, err := client.Get(u.IPCheckURL)
+	if err != nil {
+		return "", err
+	}
+
+	if resp.StatusCode != 200 {
+		return "", fmt.Errorf(
+			"Got a %d response from %s",
+			resp.StatusCode, u.IPCheckURL,
+		)
+	}
+
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	return string(body), nil
+}
+
+// ZoneID finds the zone ID for the relevant Host.
+func (u *Updater) ZoneID(host string) (string, error) {
+	zones, err := u.API.ListZones()
+	if err != nil {
+		return "", err
+	}
+
+	for _, zone := range zones {
+		if strings.HasSuffix(host, zone.Name) {
+			return zone.ID, nil
+		}
+	}
+
+	return "", fmt.Errorf("No zone found for \"%s\"", host)
+}
+
+// RecordID finds the host's DNS record ID.
+func (u *Updater) RecordID(host string, zoneID string) (string, error) {
+	records, err := u.API.DNSRecords(zoneID, cloudflare.DNSRecord{})
+	if err != nil {
+		return "", err
+	}
+
+	for _, r := range records {
+		if r.Type == "A" && r.Name == host {
+			return r.ID, nil
+		}
+	}
+
+	return "", fmt.Errorf("No A type record found for \"%s\"", host)
+}