From 62002841db885a918bcff1733b7b66db524436ee Mon Sep 17 00:00:00 2001
From: phga <toerd@posteo.de>
Date: Tue, 13 Apr 2021 21:28:11 +0200
Subject: [PATCH] Init: Quick and dirty

---
 .gitignore               |  2 +
 README.md                |  1 +
 build/app/Dockerfile     |  7 ++++
 build/docker-compose.yml | 12 ++++++
 cmd/dd/config.go         | 34 +++++++++++++++++
 cmd/dd/dd.go             | 79 ++++++++++++++++++++++++++++++++++++++++
 go.mod                   |  3 ++
 7 files changed, 138 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 README.md
 create mode 100644 build/app/Dockerfile
 create mode 100644 build/docker-compose.yml
 create mode 100644 cmd/dd/config.go
 create mode 100644 cmd/dd/dd.go
 create mode 100644 go.mod

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..86eccc2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+configs/*
+cmd/tt/tt
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..720d2c3
--- /dev/null
+++ b/README.md
@@ -0,0 +1 @@
+Tiny DDNS service I wrote because I needed to move VPS  and did not want to use the old one written in Python.
\ No newline at end of file
diff --git a/build/app/Dockerfile b/build/app/Dockerfile
new file mode 100644
index 0000000..8a4e356
--- /dev/null
+++ b/build/app/Dockerfile
@@ -0,0 +1,7 @@
+FROM golang:1.16.2
+
+ENV GO111MODULE=off
+RUN go get -u -d g.phga.de/phga/dd/...
+WORKDIR /go/src/g.phga.de/phga/dd/cmd/dd
+RUN go build
+CMD ["./dd"]
\ No newline at end of file
diff --git a/build/docker-compose.yml b/build/docker-compose.yml
new file mode 100644
index 0000000..2599f5c
--- /dev/null
+++ b/build/docker-compose.yml
@@ -0,0 +1,12 @@
+version: '3'
+
+services:
+  dd:
+    build:
+      context: ./app
+      dockerfile: Dockerfile
+    restart: 'always'
+    ports:
+      - 8000:6969
+    volumes:
+      - /srv/dd/configs:/go/src/g.phga.de/phga/dd/configs
\ No newline at end of file
diff --git a/cmd/dd/config.go b/cmd/dd/config.go
new file mode 100644
index 0000000..ff9f30f
--- /dev/null
+++ b/cmd/dd/config.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"encoding/json"
+	"log"
+	"os"
+)
+
+type Config struct {
+	WebPort        string                       `json:"web_port"`
+	WebDomain      string                       `json:"web_domain"`
+	WebAdmin       string                       `json:"web_admin"`
+	WebAdminPass   string                       `json:"web_admin_pass"`
+	MailUser       string                       `json:"mail_user"`
+	MailPass       string                       `json:"mail_pass"`
+	MailSmtpServer string                       `json:"mail_smtp_server"`
+	MailSmtpPort   string                       `json:"mail_smtp_port"`
+	DdUsers        map[string]map[string]string `json:"dd_users"`
+	DnsTTL         int                          `json:"dns_ttl"`
+}
+
+var config Config
+
+func init() {
+	f, err := os.Open("../../configs/config.json")
+	if err != nil {
+		log.Fatalln(err, "Could not read config file")
+	}
+	defer f.Close()
+	err = json.NewDecoder(f).Decode(&config)
+	if err != nil {
+		log.Fatalln(err, "Could not decode config file")
+	}
+}
diff --git a/cmd/dd/dd.go b/cmd/dd/dd.go
new file mode 100644
index 0000000..83a14e5
--- /dev/null
+++ b/cmd/dd/dd.go
@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+// https://dd.phga.de/dd?usr=<username>&pw=<passwd>
+func main() {
+	// cheap routing
+	http.HandleFunc("/dd", handleDynamicUpdate)
+
+	log.Fatalln(http.ListenAndServe(":"+config.WebPort, nil))
+}
+
+func handleDynamicUpdate(w http.ResponseWriter, r *http.Request) {
+	up := r.URL.Query()
+	ip := r.Header.Get("X-FORWARDED-FOR")
+
+	if len(ip) < 1 {
+		ip = strings.Split(r.RemoteAddr, ":")[0]
+	}
+
+	if len(up) != 2 {
+		log.Println("Attempted update for:", ip)
+		log.Println("Not enough arguments provided:", up)
+		return
+	}
+
+	for k, v := range config.DdUsers {
+		if k == up["usr"][0] {
+			if v["password"] == up["pwd"][0] {
+				log.Println("Starting update for:", ip, "(", v["domain"], ")")
+				// Do the update via nsupdate
+				err := updateDnsRecord(v["domain"], ip, v["hmac"], v["keyname"], v["secret"])
+				if err != nil {
+					log.Println("nsupdate failed:", err)
+				} else {
+					log.Println("nsupdate succeeded!")
+				}
+			} else {
+				log.Println("Wrong Secret provided!")
+			}
+		}
+	}
+
+}
+
+func updateDnsRecord(domain string, ip string, hmac string, keyname string, secret string) error {
+	f, err := os.Create("/tmp/update.dns")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	update := fmt.Sprintf(`server 127.0.0.1
+                           key %s:%s %s
+                           update add %s %d a %s
+                           send`, hmac, keyname, secret, domain, config.DnsTTL, ip)
+
+	_, err = io.WriteString(f, update)
+	if err != nil {
+		return err
+	}
+	err = f.Sync()
+	if err != nil {
+		return err
+	}
+
+	nsupdate := exec.Command("nsupdate", "/tmp/update.dns")
+	out, err := nsupdate.Output()
+	log.Println(string(out))
+	return err
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..31aeece
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module g.phga.de/phga/dd
+
+go 1.16