Bump version to 1.2.0

README.md

@@ -1,4 +1,4 @@
-# smtp-proxy
+# smtprelay
 
 Simple Golang based SMTP relay/proxy server that accepts mail via SMTP
 and forwards it directly to another SMTP server.
@@ -25,5 +25,5 @@ produces mail.
 * Authentication support with file (LOGIN, PLAIN)
 * Enforce encryption for authentication
 * Forwards all mail to a smarthost (GMail, MailGun or any other SMTP server)
-* Small codebase (smtp-proxy ~250 LoC, chrj/smtpd ~1200 LoC)
+* Small codebase
 * IPv6 support

auth.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"os"
+	"strings"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	filename string
+)
+
+func AuthLoadFile(file string) error {
+	f, err := os.Open(file)
+	if err != nil {
+		return err
+	}
+	f.Close()
+
+	filename = file
+	return nil
+}
+
+func AuthReady() bool {
+	return (filename != "")
+}
+
+func AuthFetch(username string) (string, string, error) {
+	if ! AuthReady() {
+		return "", "", errors.New("Authentication file not specified. Call LoadFile() first")
+	}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return "", "", err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		parts := strings.Fields(scanner.Text())
+
+		if len(parts) != 3 {
+			continue
+		}
+
+		if strings.ToLower(username) == strings.ToLower(parts[0]) {
+			return parts[1], parts[2], nil
+		}
+	}
+
+	return "", "", errors.New("User not found")
+}
+
+func AuthCheckPassword(username string, secret string) error {
+	hash, _, err := AuthFetch(username)
+	if err != nil {
+		return err
+	}
+	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(secret)) == nil {
+		return nil
+	}
+	return errors.New("Password invalid")
+}
+

config.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"flag"
+
+	"github.com/vharitonsky/iniflags"
+)
+
+const (
+	VERSION = "1.2.0"
+)
+
+var (
+	logFile    = flag.String("logfile", "/var/log/smtprelay.log", "Path to logfile")
+	hostName   = flag.String("hostname", "localhost.localdomain", "Server hostname")
+	welcomeMsg = flag.String("welcome_msg", "", "Welcome message for SMTP session")
+	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)")
+	allowedNets = flag.String("allowed_nets", "127.0.0.1/8 ::1/128", "Networks allowed to send mails")
+	allowedSender = flag.String("allowed_sender", "", "Regular expression for valid FROM EMail adresses")
+	allowedRecipients = flag.String("allowed_recipients", "", "Regular expression for valid TO EMail adresses")
+	allowedUsers = flag.String("allowed_users", "", "Path to file with valid users/passwords")
+	remoteHost = flag.String("remote_host", "smtp.gmail.com:587", "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")
+	versionInfo= flag.Bool("version", false, "Show version information")
+)
+
+func ConfigLoad() {
+	iniflags.Parse()
+}

go.mod

@@ -1,6 +1,7 @@
-module code.bluelife.at/decke/smtp-proxy
+module code.bluelife.at/decke/smtprelay
 
 require (
 	github.com/chrj/smtpd v0.1.2
 	github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de
+	golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9
 )

go.sum

@@ -3,3 +3,5 @@ github.com/chrj/smtpd v0.1.2/go.mod h1:jt4ydELuZmqhn9hn3YpEPV1dY00aOB+Q1nWXnBDFK
 github.com/eaigner/dkim v0.0.0-20150301120808-6fe4a7ee9cfb/go.mod h1:FSCIHbrqk7D01Mj8y/jW+NS1uoCerr+ad+IckTHTFf4=
 github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de h1:fkw+7JkxF3U1GzQoX9h69Wvtvxajo5Rbzy6+YMMzPIg=
 github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de/go.mod h1:irMhzlTz8+fVFj6CH2AN2i+WI5S6wWFtK3MBCIxIpyI=
+golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9 h1:mKdxBk7AujPs8kU4m80U72y/zjbZ3UcXC7dClwKbUI0=
+golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=

main.go

@@ -1,9 +1,7 @@
 package main
 
 import (
-	"bufio"
 	"crypto/tls"
-	"flag"
 	"fmt"
 	"io"
 	"log"
@@ -15,29 +13,6 @@ import (
 	"time"
 
 	"github.com/chrj/smtpd"
-	"github.com/vharitonsky/iniflags"
-)
-
-const (
-	VERSION = "1.1.0"
-)
-
-var (
-	logFile    = flag.String("logfile", "/var/log/smtpd-proxy.log", "Path to logfile")
-	hostName   = flag.String("hostname", "localhost.localdomain", "Server hostname")
-	welcomeMsg = flag.String("welcome_msg", "", "Welcome message for SMTP session")
-	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)")
-	allowedNets = flag.String("allowed_nets", "127.0.0.1/8 ::1/128", "Networks allowed to send mails")
-	allowedSender = flag.String("allowed_sender", "", "Regular expression for valid FROM EMail adresses")
-	allowedRecipients = flag.String("allowed_recipients", "", "Regular expression for valid TO EMail adresses")
-	allowedUsers = flag.String("allowed_users", "", "Path to file with valid users/passwords")
-	remoteHost = flag.String("remote_host", "smtp.gmail.com:587", "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")
-	versionInfo= flag.Bool("version", false, "Show version information")
 )
 
 func connectionChecker(peer smtpd.Peer) error {
@@ -62,6 +37,18 @@ func connectionChecker(peer smtpd.Peer) error {
 }
 
 func senderChecker(peer smtpd.Peer, addr string) error {
+	// check sender address from auth file if user is authenticated
+	if *allowedUsers != "" && peer.Username != "" {
+		_, email, err := AuthFetch(peer.Username)
+		if err != nil {
+			return smtpd.Error{Code: 451, Message: "Bad sender address"}
+		}
+
+		if strings.ToLower(addr) != strings.ToLower(email) {
+			return smtpd.Error{Code: 451, Message: "Bad sender address"}
+		}
+	}
+
 	if *allowedSender == "" {
 		return nil
 	}
@@ -98,27 +85,12 @@ func recipientChecker(peer smtpd.Peer, addr string) error {
 }
 
 func authChecker(peer smtpd.Peer, username string, password string) error {
-	file, err := os.Open(*allowedUsers)
+	err := AuthCheckPassword(username, password)
 	if err != nil {
-		log.Printf("User file not found %v", err)
+		log.Printf("Auth error: %v\n", err)
 		return smtpd.Error{Code: 535, Message: "Authentication credentials invalid"}
 	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		parts := strings.Fields(scanner.Text())
-
-		if len(parts) != 2 {
-			continue
-		}
-
-		if username == parts[0] && password == parts[1] {
-			return nil
-		}
-	}
-
-	return smtpd.Error{Code: 535, Message: "Authentication credentials invalid"}
+	return nil
 }
 
 func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
@@ -164,10 +136,10 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 
 func main() {
 
-	iniflags.Parse()
+	ConfigLoad()
 
 	if *versionInfo {
-		fmt.Printf("smtpd-proxy/%s\n", VERSION)
+		fmt.Printf("smtprelay/%s\n", VERSION)
 		os.Exit(0)
 	}
 
@@ -196,6 +168,11 @@ func main() {
 		}
 
 		if *allowedUsers != "" {
+			err := AuthLoadFile(*allowedUsers)
+			if err != nil {
+				log.Fatalf("Authentication file: %s\n", err)
+			}
+
 			server.Authenticator = authChecker
 		}
 

smtp.go

@@ -67,7 +67,7 @@ func NewClient(conn net.Conn, host string) (*Client, error) {
 		text.Close()
 		return nil, err
 	}
-	c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"}
+	c := &Client{Text: text, conn: conn, serverName: host, localName: *hostName}
 	_, c.tls = conn.(*tls.Conn)
 	return c, nil
 }

smtprelay.ini

@@ -1,7 +1,7 @@
-; smtp-proxy configuration
+; smtprelay configuration
 
 ; Logfile
-;logfile = /var/log/smtpd-proxy.log
+;logfile = /var/log/smtprelay.log
 
 ; Hostname for this SMTP server
 ;hostname = "localhost.localdomain"
@@ -37,7 +37,7 @@
 
 ; File which contains username and password used for
 ; authentication before they can send mail.
-; File format: username password
+; File format: username bcrypt-hash email
 ;allowed_users =
 
 ; Relay all mails to this SMTP server