Add SystemD unit file

.github/workflows/go.yml

@@ -7,10 +7,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.16
+    - name: Set up Go 1.15
       uses: actions/setup-go@v2.1.3
       with:
-        go-version: 1.16
+        go-version: 1.15
       id: go
 
     - name: Check out code into the Go module directory

.github/workflows/release.yaml

@@ -20,11 +20,11 @@ jobs:
     - name: Set BUILD_TIME env
       run: echo BUILD_TIME=$(date) >> ${GITHUB_ENV}
       
-    - uses: wangyoucao577/go-release-action@v1.16
+    - uses: wangyoucao577/go-release-action@v1.15
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         goos: ${{ matrix.goos }}
         goarch: ${{ matrix.goarch }}
-        goversion: "https://golang.org/dl/go1.16.3.linux-amd64.tar.gz"
+        goversion: "https://golang.org/dl/go1.15.8.linux-amd64.tar.gz"
         extra_files: LICENSE README.md smtprelay.ini
         ldflags: -s -w -X "main.appVersion=${{ env.APP_VERSION }}" -X "main.buildTime=${{ env.BUILD_TIME }}"

config.go

@@ -3,9 +3,8 @@ package main
 import (
 	"flag"
 	"net"
-	"net/smtp"
 	"regexp"
-	"strings"
+	"net/smtp"
 
 	"github.com/vharitonsky/iniflags"
 	"github.com/sirupsen/logrus"
@@ -22,8 +21,7 @@ var (
 	logLevel          = flag.String("log_level", "info", "Minimum log level to output")
 	hostName          = flag.String("hostname", "localhost.localdomain", "Server hostname")
 	welcomeMsg        = flag.String("welcome_msg", "", "Welcome message for SMTP session")
-	listenStr         = flag.String("listen", "127.0.0.1:25 [::1]:25", "Address and port to listen for incoming SMTP")
-	listenAddrs       = []protoAddr{}
+	listen            = flag.String("listen", "127.0.0.1:25 [::1]:25", "Address and port to listen for incoming SMTP")
 	localCert         = flag.String("local_cert", "", "SSL certificate for STARTTLS/TLS")
 	localKey          = flag.String("local_key", "", "SSL private key for STARTTLS/TLS")
 	localForceTLS     = flag.Bool("local_forcetls", false, "Force STARTTLS (needs local_cert and local_key)")
@@ -43,10 +41,6 @@ var (
 	versionInfo       = flag.Bool("version", false, "Show version information")
 )
 
-func localAuthRequired() bool {
-	return *allowedUsers != ""
-}
-
 
 func setupAllowedNetworks() {
 	for _, netstr := range splitstr(*allowedNetsStr, ' ') {
@@ -136,39 +130,6 @@ func setupRemoteAuth() {
 	}
 }
 
-type protoAddr struct {
-	protocol string
-	address  string
-}
-
-func splitProto(s string) protoAddr {
-	idx := strings.Index(s, "://")
-	if idx == -1 {
-		return protoAddr {
-			address:  s,
-		}
-	}
-	return protoAddr {
-		protocol: s[0 : idx],
-		address:  s[idx+3 : len(s)],
-	}
-}
-
-func setupListeners() {
-	for _, listenAddr := range strings.Split(*listenStr, " ") {
-		pa := splitProto(listenAddr)
-
-		if localAuthRequired() && pa.protocol == "" {
-			log.WithField("address", pa.address).
-				Fatal("Local authentication (via allowed_users file) " +
-				      "not allowed with non-TLS listener")
-		}
-
-
-		listenAddrs = append(listenAddrs, pa)
-	}
-}
-
 func ConfigLoad() {
 	iniflags.Parse()
 
@@ -182,5 +143,4 @@ func ConfigLoad() {
 	setupAllowedNetworks()
 	setupAllowedPatterns()
 	setupRemoteAuth()
-	setupListeners()
 }

config_test.go

@@ -1,44 +0,0 @@
-package main
-
-import (
-	"testing"
-)
-
-func TestSplitProto(t *testing.T) {
-	var tests = []struct {
-		input      string
-		proto      string
-		addr       string
-	}{
-		{
-			input:      "localhost",
-			proto:      "",
-			addr:       "localhost",
-		},
-		{
-			input:      "tls://my.local.domain",
-			proto:      "tls",
-			addr:       "my.local.domain",
-		},
-		{
-			input:      "starttls://my.local.domain",
-			proto:      "starttls",
-			addr:       "my.local.domain",
-		},
-	}
-
-	for i, test := range tests {
-		testName := test.input
-		t.Run(testName, func(t *testing.T) {
-			pa := splitProto(test.input)
-			if pa.protocol != test.proto {
-				t.Errorf("Testcase %d: Incorrect proto: expected %v, got %v",
-					i, test.proto, pa.protocol)
-			}
-			if pa.address != test.addr {
-				t.Errorf("Testcase %d: Incorrect addr: expected %v, got %v",
-					i, test.addr, pa.address)
-			}
-		})
-	}
-}

main.go

@@ -81,7 +81,7 @@ func addrAllowed(addr string, allowedAddrs []string) bool {
 
 func senderChecker(peer smtpd.Peer, addr string) error {
 	// check sender address from auth file if user is authenticated
-	if localAuthRequired() && peer.Username != "" {
+	if *allowedUsers != "" && peer.Username != "" {
 		user, err := AuthFetch(peer.Username)
 		if err != nil {
 			// Shouldn't happen: authChecker already validated username+password
@@ -276,7 +276,7 @@ func main() {
 		Debug("starting smtprelay")
 
 	// Load allowed users file
-	if localAuthRequired() {
+	if *allowedUsers != "" {
 		err := AuthLoadFile(*allowedUsers)
 		if err != nil {
 			log.WithField("file", *allowedUsers).
@@ -288,9 +288,7 @@ func main() {
 	var servers []*smtpd.Server
 
 	// Create a server for each desired listen address
-	for _, listen := range listenAddrs {
-		logger := log.WithField("address", listen.address)
-
+	for _, listenAddr := range strings.Split(*listen, " ") {
 		server := &smtpd.Server{
 			Hostname:          *hostName,
 			WelcomeMessage:    *welcomeMsg,
@@ -300,38 +298,44 @@ func main() {
 			Handler:           mailHandler,
 		}
 
-		if localAuthRequired() {
+		if *allowedUsers != "" {
 			server.Authenticator = authChecker
 		}
 
 		var lsnr net.Listener
 		var err error
 
-		switch listen.protocol {
-		case "":
-			logger.Info("listening on address")
-			lsnr, err = net.Listen("tcp", listen.address)
+		if strings.Index(listenAddr, "://") == -1 {
+			log.WithField("address", listenAddr).
+				Info("listening on address")
+
+			lsnr, err = net.Listen("tcp", listenAddr)
+		} else if strings.HasPrefix(listenAddr, "starttls://") {
+			listenAddr = strings.TrimPrefix(listenAddr, "starttls://")
 
-		case "starttls":
 			server.TLSConfig = getTLSConfig()
 			server.ForceTLS = *localForceTLS
 
-			logger.Info("listening on address (STARTTLS)")
-			lsnr, err = net.Listen("tcp", listen.address)
+			log.WithField("address", listenAddr).
+				Info("listening on address (STARTTLS)")
+			lsnr, err = net.Listen("tcp", listenAddr)
+		} else if strings.HasPrefix(listenAddr, "tls://") {
+			listenAddr = strings.TrimPrefix(listenAddr, "tls://")
 
-		case "tls":
 			server.TLSConfig = getTLSConfig()
 
-			logger.Info("listening on address (TLS)")
-			lsnr, err = tls.Listen("tcp", listen.address, server.TLSConfig)
-
-		default:
-			logger.WithField("protocol", listen.protocol).
+			log.WithField("address", listenAddr).
+				Info("listening on address (TLS)")
+			lsnr, err = tls.Listen("tcp", listenAddr, server.TLSConfig)
+		} else {
+			log.WithField("address", listenAddr).
 				Fatal("unknown protocol in listen address")
 		}
 
 		if err != nil {
-			logger.WithError(err).Fatal("error starting listener")
+			log.WithFields(logrus.Fields{
+				"address": listenAddr,
+			}).WithError(err).Fatal("error starting listener")
 		}
 		servers = append(servers, server)
 

service_files/smtprelay.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=SMTP Relay
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=/opt/smtprelay/bin/smtprelay -config /etc/smtprelay/smtprelay.ini
+
+[Install]
+WantedBy=multi-user.target