From 10cf806b73bfce40ef013e609474e0e79ac0adf1 Mon Sep 17 00:00:00 2001
From: David Lick <david@dvdt.dev>
Date: Sun, 12 Sep 2021 20:09:08 -0400
Subject: [PATCH] Initial commit

---
 digitalocean/client.go | 90 ++++++++++++++++++++++++++++++++++++++++++
 digitalocean/errors.go |  9 +++++
 digitalocean/models.go | 12 ++++++
 go.mod                 |  3 ++
 main.go                | 54 +++++++++++++++++++++++++
 5 files changed, 168 insertions(+)
 create mode 100644 digitalocean/client.go
 create mode 100644 digitalocean/errors.go
 create mode 100644 digitalocean/models.go
 create mode 100644 go.mod
 create mode 100644 main.go

diff --git a/digitalocean/client.go b/digitalocean/client.go
new file mode 100644
index 0000000..0699dae
--- /dev/null
+++ b/digitalocean/client.go
@@ -0,0 +1,90 @@
+package digitalocean
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type client struct {
+	baseUrl    string
+	domain     string
+	token      string
+	httpClient *http.Client
+}
+
+func NewClient(baseUrl, token, domain string) *client {
+	return &client{
+		baseUrl: baseUrl,
+		domain:  domain,
+		token:   token,
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+func (c *client) GetARecordID() (string, error) {
+	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("%s/v2/domains/%s/records", c.baseUrl, c.domain), nil)
+	if err != nil {
+		return "", err
+	}
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.token))
+
+	var records RecordsResponse
+	err = c.doRequest(req, &records)
+	if err != nil {
+		return "", err
+	}
+
+	for _, record := range records.DomainRecords {
+		if record.Name == "vpn" && record.Type == "A" {
+			return strconv.Itoa(int(record.Id)), nil
+		}
+	}
+
+	return "", ErrNotFound
+}
+
+func (c *client) SetARecord(id, ip string) error {
+	body := fmt.Sprintf(`{"data":%q}`, strings.ReplaceAll(ip, "\n", ""))
+	req, err := http.NewRequest(http.MethodPatch, fmt.Sprintf("%s/v2/domains/%s/records/%s", c.baseUrl, c.domain, id), bytes.NewBufferString(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.token))
+	req.Header.Add("Content-Type", "application/json")
+
+	var resp map[string]interface{}
+	err = c.doRequest(req, &resp)
+	return err
+}
+
+func (c *client) doRequest(req *http.Request, output interface{}) error {
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= http.StatusInternalServerError {
+		return fmt.Errorf("%w: statuscode %d", ErrServerError, resp.StatusCode)
+	}
+
+	if resp.StatusCode >= http.StatusBadRequest {
+		return fmt.Errorf("%w: statuscode %d", ErrClientError, resp.StatusCode)
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(body, &output)
+	return err
+}
diff --git a/digitalocean/errors.go b/digitalocean/errors.go
new file mode 100644
index 0000000..f776a9c
--- /dev/null
+++ b/digitalocean/errors.go
@@ -0,0 +1,9 @@
+package digitalocean
+
+import "errors"
+
+var (
+	ErrNotFound    = errors.New("not found")
+	ErrClientError = errors.New("client error")
+	ErrServerError = errors.New("server error")
+)
diff --git a/digitalocean/models.go b/digitalocean/models.go
new file mode 100644
index 0000000..4231982
--- /dev/null
+++ b/digitalocean/models.go
@@ -0,0 +1,12 @@
+package digitalocean
+
+type DomainRecords struct {
+	Data string `json:"data"`
+	Id   int64  `json:"id"`
+	Name string `json:"name"`
+	Type string `json:"type"`
+}
+
+type RecordsResponse struct {
+	DomainRecords []DomainRecords `json:"domain_records"`
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..ca4d37e
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/davidlick/digitalocean-ddns
+
+go 1.16
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..1f9657e
--- /dev/null
+++ b/main.go
@@ -0,0 +1,54 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/davidlick/digitalocean-ddns/digitalocean"
+)
+
+var (
+	client = &http.Client{}
+)
+
+func main() {
+	token := os.Getenv("DIGITALOCEAN_TOKEN")
+	doBaseUrl := os.Getenv("DIGITALOCEAN_URL")
+	doDomain := os.Getenv("DIGITALOCEAN_DOMAIN")
+
+	client := digitalocean.NewClient(doBaseUrl, token, doDomain)
+
+	ip, err := getPublicIP()
+	if err != nil {
+		log.Fatalf("failed to get public ip: %v", err)
+	}
+
+	id, err := client.GetARecordID()
+	if err != nil {
+		log.Fatalf("failed to get A record ID: %v", err)
+	}
+
+	err = client.SetARecord(id, ip)
+	if err != nil {
+		log.Fatalf("failed to set A record ip: %v", err)
+	}
+
+	log.Printf("successfully set DNS A record id %s to %s", id, ip)
+}
+
+func getPublicIP() (string, error) {
+	resp, err := http.Get("https://icanhazip.com")
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	return string(body), nil
+}