Add SystemD unit file

.github/workflows/codeql-analysis.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2.4.0
+      uses: actions/checkout@v2
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.

.github/workflows/go.yml

@@ -7,14 +7,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.17
-      uses: actions/setup-go@v2.1.4
+    - name: Set up Go 1.15
+      uses: actions/setup-go@v2.1.3
       with:
-        go-version: 1.17
+        go-version: 1.15
       id: go
 
     - name: Check out code into the Go module directory
-      uses: actions/checkout@v2.4.0
+      uses: actions/checkout@v1
 
     - name: Get dependencies
       run: |

.github/workflows/release.yaml

@@ -13,18 +13,18 @@ jobs:
         goos: [freebsd, linux, windows]
         goarch: ["386", amd64]
     steps:
-    - uses: actions/checkout@v2.4.0
+    - uses: actions/checkout@v2
     
     - name: Set APP_VERSION env
       run: echo APP_VERSION=$(echo ${GITHUB_REF} | rev | cut -d'/' -f 1 | rev ) >> ${GITHUB_ENV}
     - name: Set BUILD_TIME env
       run: echo BUILD_TIME=$(date) >> ${GITHUB_ENV}
       
-    - uses: wangyoucao577/go-release-action@v1.21
+    - uses: wangyoucao577/go-release-action@v1.15
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         goos: ${{ matrix.goos }}
         goarch: ${{ matrix.goarch }}
-        goversion: "https://golang.org/dl/go1.17.3.linux-amd64.tar.gz"
+        goversion: "https://golang.org/dl/go1.15.8.linux-amd64.tar.gz"
         extra_files: LICENSE README.md smtprelay.ini
         ldflags: -s -w -X "main.appVersion=${{ env.APP_VERSION }}" -X "main.buildTime=${{ env.BUILD_TIME }}"

config.go

@@ -3,12 +3,11 @@ package main
 import (
 	"flag"
 	"net"
-	"net/smtp"
 	"regexp"
-	"strings"
+	"net/smtp"
 
-	"github.com/sirupsen/logrus"
 	"github.com/vharitonsky/iniflags"
+	"github.com/sirupsen/logrus"
 )
 
 var (
@@ -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)")
@@ -34,7 +32,6 @@ var (
 	allowedRecipStr   = flag.String("allowed_recipients", "", "Regular expression for valid TO EMail addresses")
 	allowedRecipients *regexp.Regexp
 	allowedUsers      = flag.String("allowed_users", "", "Path to file with valid users/passwords")
-	command           = flag.String("command", "", "Path to pipe command")
 	remoteHost        = flag.String("remote_host", "", "Outgoing SMTP server")
 	remoteUser        = flag.String("remote_user", "", "Username for authentication on outgoing SMTP server")
 	remotePass        = flag.String("remote_pass", "", "Password for authentication on outgoing SMTP server")
@@ -44,9 +41,6 @@ var (
 	versionInfo       = flag.Bool("version", false, "Show version information")
 )
 
-func localAuthRequired() bool {
-	return *allowedUsers != ""
-}
 
 func setupAllowedNetworks() {
 	for _, netstr := range splitstr(*allowedNetsStr, ' ') {
@@ -61,7 +55,7 @@ func setupAllowedNetworks() {
 		// meaning the address refers to a host and not a network.
 		if !allowedNet.IP.Equal(baseIP) {
 			log.WithFields(logrus.Fields{
-				"given_net":  netstr,
+				"given_net": netstr,
 				"proper_net": allowedNet,
 			}).Fatal("Invalid network in allowed_nets (host bits set)")
 		}
@@ -73,7 +67,7 @@ func setupAllowedNetworks() {
 func setupAllowedPatterns() {
 	var err error
 
-	if *allowedSenderStr != "" {
+	if (*allowedSenderStr != "") {
 		allowedSender, err = regexp.Compile(*allowedSenderStr)
 		if err != nil {
 			log.WithField("allowed_sender", *allowedSenderStr).
@@ -82,7 +76,7 @@ func setupAllowedPatterns() {
 		}
 	}
 
-	if *allowedRecipStr != "" {
+	if (*allowedRecipStr != "") {
 		allowedRecipients, err = regexp.Compile(*allowedRecipStr)
 		if err != nil {
 			log.WithField("allowed_recipients", *allowedRecipStr).
@@ -92,6 +86,7 @@ func setupAllowedPatterns() {
 	}
 }
 
+
 func setupRemoteAuth() {
 	logger := log.WithField("remote_auth", *remoteAuthStr)
 
@@ -122,7 +117,7 @@ func setupRemoteAuth() {
 	host, _, err := net.SplitHostPort(*remoteHost)
 	if err != nil {
 		logger.WithField("remote_host", *remoteHost).
-			Fatal("Invalid remote_host")
+			   Fatal("Invalid remote_host")
 	}
 
 	switch *remoteAuthStr {
@@ -135,50 +130,17 @@ 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:],
-	}
-}
-
-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()
 
 	// Set up logging as soon as possible
 	setupLogger()
 
-	if *remoteHost == "" && *command == "" {
-		log.Warn("no remote_host or command set; mail will not be forwarded!")
+	if (*remoteHost == "") {
+		log.Warn("remote_host not set; mail will not be forwarded!")
 	}
 
 	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)
-			}
-		})
-	}
-}

go.mod

@@ -1,8 +1,8 @@
 module github.com/decke/smtprelay
 
 require (
-	github.com/chrj/smtpd v0.3.1
-	github.com/google/uuid v1.3.0
+	github.com/chrj/smtpd v0.3.0
+	github.com/google/uuid v1.2.0
 	github.com/sirupsen/logrus v1.8.1
 	github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de
 	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad

go.sum

@@ -1,9 +1,10 @@
-github.com/chrj/smtpd v0.3.1 h1:kogHFkbFdKaoH3bgZkqNC9uVtKYOFfM3uV3rroBdooE=
-github.com/chrj/smtpd v0.3.1/go.mod h1:JtABvV/LzvLmEIzy0NyDnrfMGOMd8wy5frAokwf6J9Q=
+github.com/chrj/smtpd v0.3.0 h1:cw1LSHDOz7N3XbkcZSF/bue9dh7ATKk5ZksfBztV6b0=
+github.com/chrj/smtpd v0.3.0/go.mod h1:1hmG9KbrE10JG1SmvG79Krh4F6713oUrw2+gRp1oSYk=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
-github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/eaigner/dkim v0.0.0-20150301120808-6fe4a7ee9cfb/go.mod h1:FSCIHbrqk7D01Mj8y/jW+NS1uoCerr+ad+IckTHTFf4=
+github.com/google/uuid v1.2.0 h1:qJYtXnJRWmpe7m/3XlyhrsLrEURqHRM2kxzoxXqyUDs=
+github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=

logger.go

@@ -16,7 +16,7 @@ func setupLogger() {
 	log = logrus.New()
 
 	// Handle logfile
-	if *logFile == "" {
+	if (*logFile == "") {
 		log.SetOutput(os.Stderr)
 	} else {
 		writer, err := os.OpenFile(*logFile, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0600)

main.go

@@ -1,13 +1,11 @@
 package main
 
 import (
-	"bytes"
 	"crypto/tls"
 	"fmt"
 	"net"
 	"net/textproto"
 	"os"
-	"os/exec"
 	"os/signal"
 	"strings"
 	"syscall"
@@ -83,12 +81,12 @@ 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
 			log.WithFields(logrus.Fields{
-				"peer":     peer.Addr,
+				"peer": peer.Addr,
 				"username": peer.Username,
 			}).WithError(err).Warn("could not fetch auth user")
 			return smtpd.Error{Code: 451, Message: "Bad sender address"}
@@ -96,8 +94,8 @@ func senderChecker(peer smtpd.Peer, addr string) error {
 
 		if !addrAllowed(addr, user.allowedAddresses) {
 			log.WithFields(logrus.Fields{
-				"peer":           peer.Addr,
-				"username":       peer.Username,
+				"peer": peer.Addr,
+				"username": peer.Username,
 				"sender_address": addr,
 			}).Warn("sender address not allowed for authenticated user")
 			return smtpd.Error{Code: 451, Message: "Bad sender address"}
@@ -116,7 +114,7 @@ func senderChecker(peer smtpd.Peer, addr string) error {
 
 	log.WithFields(logrus.Fields{
 		"sender_address": addr,
-		"peer":           peer.Addr,
+		"peer": peer.Addr,
 	}).Warn("sender address not allowed by allowed_sender pattern")
 	return smtpd.Error{Code: 451, Message: "Bad sender address"}
 }
@@ -133,7 +131,7 @@ func recipientChecker(peer smtpd.Peer, addr string) error {
 	}
 
 	log.WithFields(logrus.Fields{
-		"peer":              peer.Addr,
+		"peer": peer.Addr,
 		"recipient_address": addr,
 	}).Warn("recipient address not allowed by allowed_recipients pattern")
 	return smtpd.Error{Code: 451, Message: "Bad recipient address"}
@@ -143,7 +141,7 @@ func authChecker(peer smtpd.Peer, username string, password string) error {
 	err := AuthCheckPassword(username, password)
 	if err != nil {
 		log.WithFields(logrus.Fields{
-			"peer":     peer.Addr,
+			"peer": peer.Addr,
 			"username": username,
 		}).WithError(err).Warn("auth error")
 		return smtpd.Error{Code: 535, Message: "Authentication credentials invalid"}
@@ -159,45 +157,21 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 
 	logger := log.WithFields(logrus.Fields{
 		"from": env.Sender,
-		"to":   env.Recipients,
+		"to": env.Recipients,
 		"peer": peerIP,
 		"host": *remoteHost,
 		"uuid": generateUUID(),
 	})
 
-	if *remoteHost == "" && *command == "" {
-		logger.Warning("no remote_host or command set; discarding mail")
-		return nil
-	}
-
-	env.AddReceivedLine(peer)
-
-	if *command != "" {
-		cmdLogger := logger.WithField("command", *command)
-
-		var stdout bytes.Buffer
-		var stderr bytes.Buffer
-
-		cmd := exec.Command(*command)
-		cmd.Stdin = bytes.NewReader(env.Data)
-		cmd.Stdout = &stdout
-		cmd.Stderr = &stderr
-
-		err := cmd.Run()
-		if err != nil {
-			cmdLogger.WithError(err).Error(stderr.String())
-			return nil
-		}
-
-		cmdLogger.Info("pipe command successful: " + stdout.String())
-	}
-
-	if *remoteHost == "" {
+	if (*remoteHost == "") {
+		logger.Warning("remote_host not set; discarding mail")
 		return nil
 	}
 
 	logger.Info("delivering mail from peer using smarthost")
 
+	env.AddReceivedLine(peer)
+
 	var sender string
 
 	if *remoteSender == "" {
@@ -223,7 +197,7 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 
 			logger.WithFields(logrus.Fields{
 				"err_code": err.Code,
-				"err_msg":  err.Msg,
+				"err_msg": err.Msg,
 			}).Error("delivery failed")
 		default:
 			smtpError = smtpd.Error{Code: 554, Message: "Forwarding failed"}
@@ -272,7 +246,7 @@ func getTLSConfig() *tls.Config {
 	if *localCert == "" || *localKey == "" {
 		log.WithFields(logrus.Fields{
 			"cert_file": *localCert,
-			"key_file":  *localKey,
+			"key_file": *localKey,
 		}).Fatal("TLS certificate/key file not defined in config")
 	}
 
@@ -302,7 +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).
@@ -314,9 +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,
@@ -326,38 +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

smtprelay.ini

@@ -78,6 +78,3 @@
 
 ; Sender e-mail address on outgoing SMTP server
 ;remote_sender = 
-
-; Pipe messages to external command
-;command = /usr/local/bin/script