From 683a8a5fc11cb2d1440308094790f25a111c8204 Mon Sep 17 00:00:00 2001
From: Joerg Lehmann <joerg.lehmann@nbit.ch>
Date: Wed, 13 Jul 2022 19:30:59 +0200
Subject: [PATCH] refactor email send functions

---
 alert.go       |  2 +-
 mail.go        | 43 ++++++++++++++++++++++++++-----------------
 persistence.go | 14 +++++++-------
 3 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/alert.go b/alert.go
index f983a18..7d982d8 100644
--- a/alert.go
+++ b/alert.go
@@ -78,7 +78,7 @@ func sendAlert(deveui string, alertMessage string) {
 	if emailalarmactive == "1" {
 		emails := strings.Split(email, ",")
 		for _, em := range emails {
-			sendEmail(em, alertMessage)
+			sendEmailMessage(em, alertMessage)
 		}
 	}
 }
diff --git a/mail.go b/mail.go
index 9c33a5f..926bac8 100644
--- a/mail.go
+++ b/mail.go
@@ -1,27 +1,39 @@
 package main
 
 import (
-	"bytes"
 	"log"
 	"net/smtp"
 )
 
-func sendEmail(username, message string) {
-	c, err := smtp.Dial("127.0.0.1:25")
+func sendEmail(mail_to, mail_default_authuser, mail_message string) {
+	var auth smtp.Auth
+	if getenv("MAILSERVER_USER", "") != "" {
+		// Set up authentication information.
+		auth = smtp.PlainAuth(
+			"",
+			getenv("MAILSERVER_USER", ""),
+			getenv("MAILSERVER_PASSWORD", ""),
+			getenv("MAILSERVER_HOST", "127.0.0.1"),
+		)
+	}
+	// Connect to the server, authenticate, set the sender and recipient,
+	// and send the email all in one step.
+	err := smtp.SendMail(
+		getenv("MAILSERVER_HOST", "127.0.0.1")+":"+getenv("MAILSERVER_PORT", "25"),
+		auth,
+		getenv("MAILSERVER_USER", mail_default_authuser),
+		[]string{mail_to},
+		[]byte(mail_message),
+	)
+
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer c.Close()
-	// Set the sender and recipient.
-	c.Mail("info@wo-bisch.ch")
-	c.Rcpt(username)
-	// Send the email body.
-	wc, err := c.Data()
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer wc.Close()
+}
+
+func sendEmailMessage(username, message string) {
 	mail_message := "To: " + username + `
+From: info@wo-bisch.ch
 Subject: ` + message + `
 
 Lieber Benutzer von wo-bisch.ch
@@ -30,8 +42,5 @@ Lieber Benutzer von wo-bisch.ch
 --
 wo-bisch.ch`
 
-	buf := bytes.NewBufferString(mail_message)
-	if _, err = buf.WriteTo(wc); err != nil {
-		log.Fatal(err)
-	}
+	sendEmail(username, "mail@wo-bisch.ch", mail_message)
 }
diff --git a/persistence.go b/persistence.go
index b804ccf..60a46b1 100644
--- a/persistence.go
+++ b/persistence.go
@@ -3,8 +3,8 @@ package main
 import (
 	"github.com/gomodule/redigo/redis"
 	"log"
-	"time"
 	"os"
+	"time"
 )
 
 var globalPool *redis.Pool
@@ -13,11 +13,11 @@ const alertsentPrefix string = "alertsent:"
 const devPrefix string = "dev:"
 
 func getenv(key, fallback string) string {
-    value := os.Getenv(key)
-    if len(value) == 0 {
-        return fallback
-    }
-    return value
+	value := os.Getenv(key)
+	if len(value) == 0 {
+		return fallback
+	}
+	return value
 }
 
 func newPool() *redis.Pool {
@@ -29,7 +29,7 @@ func newPool() *redis.Pool {
 		// Dial is an application supplied function for creating and
 		// configuring a connection.
 		Dial: func() (redis.Conn, error) {
-			c, err := redis.Dial("tcp", getenv("REDIS_CONNECTION_STRING",":6379"))
+			c, err := redis.Dial("tcp", getenv("REDIS_CONNECTION_STRING", ":6379"))
 			if err != nil {
 				panic(err.Error())
 			}