godyn/client/client.go

package client

import (
	"errors"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"
	"velvettear/godyn/config"
	"velvettear/godyn/log"
	"velvettear/godyn/notifications"
)

var wanIp string
var ipFile string

// exported function(s)
func Run() {
	timestamp := time.Now().UnixMilli()
	log.Debug("starting godyn in client mode...")
	if !config.HasValidDyndnsConfig() {
		log.Fatal("encountered an error starting godyn in client mode", "missing parameters for the dyndns provider")
	}
	interval := strconv.Itoa(config.Interval())
	notifications.Send(notifications.Notification{
		Title: "godyn started",
		Message: "interval: " + interval + " seconds\n" +
			"ip-provider: " + config.IpProviderUrl(),
		Emoji: "white_circle",
	})
	readIpFile()
	for config.Interval() > 0 {
		log.Info("waiting " + interval + " seconds before next remote/wan ip query and dyndns update...")
		time.Sleep(time.Duration(config.Interval()) * time.Second)
		updateDyndns()
	}
	log.DebugTimed("client mode finished", timestamp)
}

// unexported function(s)
func readIpFile() {
	ipFile = filepath.Join(os.TempDir(), ".ipfile")
	log.Debug("using file '" + ipFile + "' to store ip address")
	timestamp := time.Now().UnixMilli()
	bytes, error := os.ReadFile(ipFile)
	if error != nil {
		if errors.Is(error, os.ErrNotExist) {
			return
		}
		log.ErrorTimed("encountered an error reading from the '.ipfile'", timestamp, "location: '"+ipFile+"'", error.Error())
	}
	wanIp = string(bytes)
	log.DebugTimed("read latest remote/wan ip from '.ipfile'", timestamp, "value: '"+wanIp+"'", "location: '"+ipFile+"'")
}

func writeIpFile(value string) {
	timestamp := time.Now().UnixMilli()
	error := os.WriteFile(ipFile, []byte(value), 0644)
	if error != nil {
		log.ErrorTimed("encountered an error writing the '.ipfile'", timestamp, "value: '"+value+"'", "location: '"+ipFile+"'", error.Error())
		return
	}
	log.DebugTimed("wrote latest remote/wan ip to '.ipfile'", timestamp, "value: '"+wanIp+"'", "location: '"+ipFile+"'")
}

func getWANIp() (string, error) {
	timestamp := time.Now().UnixMilli()
	var ip string
	providerUrl := config.IpProviderUrl()
	response, error := http.Get(providerUrl)
	if error != nil {
		return ip, error
	}
	body, error := io.ReadAll(response.Body)
	if error != nil {
		return ip, error
	}
	ip = strings.TrimSpace(string(body))
	log.InfoTimed("got remote/wan ip '"+ip+"'", timestamp, "ip provider: '"+providerUrl+"'")
	return ip, nil
}

func buildDyndnsdUrl(wanIp string) string {
	return config.DyndnsUrl() + "?hostname=" + config.DyndnsHostname() + "&myip=" + wanIp
}

func updateDyndns() {
	timestamp := time.Now().UnixMilli()
	tmpIp, error := getWANIp()
	if error != nil {
		log.ErrorTimed("encountered an error getting the remote/wan ip", timestamp, "ip provider: '"+config.IpProviderUrl()+"'", error.Error())
	}
	if len(tmpIp) <= 0 {
		log.ErrorTimed("will not update dyndns because remote/wan ip is empty", timestamp)
	}
	if tmpIp == wanIp {
		log.InfoTimed("nothing to do - remote/wan ip has not changed", timestamp, "ip: "+wanIp)
		return
	}
	dyndnsUrl := buildDyndnsdUrl(tmpIp)
	request, error := http.NewRequest("GET", dyndnsUrl, nil)
	if error != nil {
		msg := "encountered an error creating the http request to update dyndns"
		log.ErrorTimed(msg, timestamp, error.Error())
		notifications.Send(notifications.Notification{
			Title:    "godyn",
			Message:  msg + "\n" + error.Error(),
			Priority: notifications.PRIORITY_MAX,
			Emoji:    "red_circle",
		})
		return
	}
	request.SetBasicAuth(config.DyndnsUsername(), config.DyndnsPassword())
	response, error := http.DefaultClient.Do(request)
	if error != nil {
		msg := "encountered an error updating dyndns"
		log.ErrorTimed(msg, timestamp, "url: '"+dyndnsUrl+"'", error.Error())
		notifications.Send(notifications.Notification{
			Title:    "godyn",
			Message:  msg + "\n" + error.Error(),
			Priority: notifications.PRIORITY_MAX,
			Emoji:    "red_circle",
		})
		return
	}
	bytes, error := io.ReadAll(response.Body)
	if error != nil {
		msg := "encountered an error reading the response from the dyndns provider"
		log.ErrorTimed(msg, timestamp, error.Error())
		notifications.Send(notifications.Notification{
			Title:    "godyn",
			Message:  msg + "\n" + error.Error(),
			Priority: notifications.PRIORITY_MAX,
			Emoji:    "red_circle",
		})
		return
	}
	body := strings.ToLower(strings.TrimSpace(string(bytes)))
	if !strings.Contains(body, tmpIp) {
		statuscode := strconv.Itoa(response.StatusCode)
		msg := "probably encountered an error updating dyndns"
		log.WarningTimed(msg, timestamp, "status code: "+statuscode+"'", "response: '"+body+"'")
		notifications.Send(notifications.Notification{

			Message: msg + "\n" +
				"status code: " + statuscode + "\n" +
				"response: '" + body + "'",
			Priority: notifications.PRIORITY_MAX,
			Emoji:    "red_circle",
		})
		return
	}
	notification := notifications.Notification{}
	var msg string
	if strings.Contains(body, "abuse") {
		msg = "dyndns was not updated because remote/wan ip did not change and the dyndns provider reported an abusive update"
		log.WarningTimed(msg, timestamp, "response: '"+body+"'")
		notification.Priority = notifications.PRIORITY_HIGH
		notification.Emoji = "orange_circle"
	} else if strings.Contains(body, "nochg") {
		msg = "dyndns was not updated because remote/wan ip did not change"
		log.WarningTimed(msg, timestamp, "response: '"+body+"'")
	} else {
		msg = "dyndns was updated successfully"
		log.InfoTimed(msg, timestamp, "response: '"+strings.TrimSpace(string(bytes))+"'")
		msg += "\n" + "ip-address: " + wanIp
		notification.Priority = notifications.PRIORITY_MAX
		notification.Emoji = "green_circle"
	}
	notification.Message = msg
	notifications.Send(notification)
	wanIp = tmpIp
	writeIpFile(wanIp)
}