add LOGIN auth support

.golangci.yml

@@ -0,0 +1,73 @@
+linters-settings:
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - experimental
+      - performance
+      - style
+    disabled-checks:
+      - dupImport # https://github.com/go-critic/go-critic/issues/845
+      - ifElseChain
+      - octalLiteral
+      - whyNoLint
+      - wrapperFunc
+  govet:
+    check-shadowing: true
+  misspell:
+    locale: US
+
+linters:
+  # please, do not use `enable-all`: it's deprecated and will be removed soon.
+  # inverted configuration with `enable-all` and `disable` is not scalable during updates of golangci-lint
+  disable-all: true
+  enable:
+    - bodyclose
+    - deadcode
+    - depguard
+    - dogsled
+    - dupl
+    - errcheck
+#    - funlen
+    - gochecknoinits
+    - goconst
+#    - gocritic
+    - gocyclo
+    - gofmt
+    - goimports
+    - golint
+    - gomnd
+    - goprintffuncname
+    - gosec
+    - gosimple
+    - govet
+    - ineffassign
+    - interfacer
+    - lll
+    - misspell
+    - nakedret
+#    - nolintlint
+    - rowserrcheck
+    - scopelint
+    - staticcheck
+    - structcheck
+    - stylecheck
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - varcheck
+    - whitespace
+
+  # don't enable:
+  # - asciicheck
+  # - gochecknoglobals
+  # - gocognit
+  # - godot
+  # - godox
+  # - goerr113
+  # - maligned
+  # - nestif
+  # - prealloc
+  # - testpackage
+  # - wsl
+

.vscode/settings.json

@@ -1,5 +1,8 @@
 {
 	"cSpell.words": [
-		"myname"
+		"myname",
+		"HELO",
+		"EHLO",
+		"gosec"
 	]
 }

README.md

@@ -12,14 +12,14 @@ Some older appliances such as scanners, multi-function printers, RAID cards or N
 
 Run `mailrelay` on a local PC or server and set your device (e.g. scanner) to send mail to it.
 
-`mailrelay` is written in Go, and can be compiled for any Go supported platform including Linux, MacOS, Windows.
+`mailrelay` can be compiled for any Go supported platform including Linux, MacOS, Windows.
 
 ## Encryption
 
 `mailrelay` uses TLS to connect to your SMTP provider. By default implicit TLS connections are assumed, meaning the connection is established
 using TLS at the socket level. This is in accordance with [RFC 8314 section 3](https://tools.ietf.org/html/rfc8314#section-3). These connections usually use port 465.
 
-However, some providers do not adhere to this recommendation (I'm looking at you Office365!) and only support the legacy STARTTLS command, which expects a non-encrypted socket connection at first, which is then upgraded to TLS. To enable this, set `smtp_starttls` to `true` in your config.
+However, some providers do not adhere to this recommendation (I'm looking at you Office365!) and only support the legacy STARTTLS command, which expects a non-encrypted socket connection at first, which is then upgraded to TLS. To enable this, set `smtp_starttls` to `true` in your config. You may also need to set `smtp_login_auth_type` to `true` which enables the legacy [LOGIN authentication](https://www.ietf.org/archive/id/draft-murchison-sasl-login-00.txt) method.
 These connections usually use port 587.
 
 ## Testing your configuration
@@ -43,6 +43,7 @@ On local PC (192.168.1.54) create file `/etc/mailrelay.json` with contents:
     "smtp_starttls": false,
     "smtp_username": "username@fastmail.com",
     "smtp_password": "secretAppPassword",
+    "smtp_login_auth_type": false,
     "local_listen_ip": "0.0.0.0",
     "local_listen_port": 2525,
     "allowed_hosts": ["*"]

auth.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"net/smtp"
+)
+
+type loginAuth struct {
+	username, password string
+}
+
+// LoginAuth provides a simple implementation of LOGIN authorization of SMTP as
+// described here: https://www.ietf.org/archive/id/draft-murchison-sasl-login-00.txt
+func LoginAuth(username, password string) smtp.Auth {
+	return &loginAuth{username, password}
+}
+
+func (a *loginAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
+	return "LOGIN", []byte{}, nil
+}
+
+func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
+	if more {
+		switch string(fromServer) {
+		case "User Name", "Username:":
+			return []byte(a.username), nil
+		case "Password", "Password:":
+			return []byte(a.password), nil
+		default:
+			return nil, fmt.Errorf("unknown server response \"%s\"", string(fromServer))
+		}
+	}
+	return nil, nil
+}

client.go

@@ -19,7 +19,7 @@ type closeable interface {
 
 // sendMail sends the contents of the envelope to a SMTP server.
 func sendMail(e *mail.Envelope, config *relayConfig) error {
-	server := fmt.Sprintf("%s:%d", config.SMTPServer, config.SMTPPort)
+	server := fmt.Sprintf("%s:%d", config.Server, config.Port)
 	to := getTo(e)
 
 	var msg bytes.Buffer
@@ -33,8 +33,8 @@ func sendMail(e *mail.Envelope, config *relayConfig) error {
 	var writer io.WriteCloser
 
 	tlsconfig := &tls.Config{
-		InsecureSkipVerify: true,
+		InsecureSkipVerify: config.SkipVerify, //nolint:gosec
-		ServerName:         config.SMTPServer,
+		ServerName:         config.Server,
 	}
 
 	if config.STARTTLS {
@@ -47,7 +47,7 @@ func sendMail(e *mail.Envelope, config *relayConfig) error {
 		}
 	}
 
-	if client, err = smtp.NewClient(conn, config.SMTPServer); err != nil {
+	if client, err = smtp.NewClient(conn, config.Server); err != nil {
 		close(conn, "conn")
 		return errors.Wrap(err, "newclient error")
 	}
@@ -58,15 +58,8 @@ func sendMail(e *mail.Envelope, config *relayConfig) error {
 		}
 	}(&shouldCloseClient)
 
-	if config.STARTTLS {
+	if err = handshake(client, config, tlsconfig); err != nil {
-		if err = client.StartTLS(tlsconfig); err != nil {
+		return err
-			return errors.Wrap(err, "starttls error")
-		}
-	}
-
-	auth := smtp.PlainAuth("", config.SMTPUsername, config.SMTPPassword, config.SMTPServer)
-	if err = client.Auth(auth); err != nil {
-		return errors.Wrap(err, "auth error")
 	}
 
 	if err = client.Mail(e.MailFrom.String()); err != nil {
@@ -98,10 +91,30 @@ func sendMail(e *mail.Envelope, config *relayConfig) error {
 	return nil
 }
 
+func handshake(client *smtp.Client, config *relayConfig, tlsConfig *tls.Config) error {
+	if config.STARTTLS {
+		if err := client.StartTLS(tlsConfig); err != nil {
+			return errors.Wrap(err, "starttls error")
+		}
+	}
+
+	var auth smtp.Auth
+	if config.LoginAuthType {
+		auth = LoginAuth(config.Username, config.Password)
+	} else {
+		auth = smtp.PlainAuth("", config.Username, config.Password, config.Server)
+	}
+
+	if err := client.Auth(auth); err != nil {
+		return errors.Wrap(err, "auth error")
+	}
+	return nil
+}
+
 func close(c closeable, what string) {
 	err := c.Close()
 	if err != nil {
-		fmt.Printf("!!!!! Error closing %s: %v\n", what, err)
+		fmt.Printf("Error closing %s: %v\n", what, err)
 	}
 }
 
@@ -122,8 +135,8 @@ func isQuitError(err error) bool {
 // getTo returns the array of email addresses in the envelope.
 func getTo(e *mail.Envelope) []string {
 	var ret []string
-	for _, addy := range e.RcptTo {
+	for i := range e.RcptTo {
-		ret = append(ret, addy.String())
+		ret = append(ret, e.RcptTo[i].String())
 	}
 	return ret
 }

go.mod

@@ -6,12 +6,12 @@ require (
 	github.com/asaskevich/EventBus v0.0.0-20180103000110-68a521d7cbbb // indirect
 	github.com/flashmob/go-guerrilla v1.6.1
 	github.com/go-sql-driver/mysql v1.5.0 // indirect
-	github.com/onsi/ginkgo v1.12.0 // indirect
+	github.com/kr/text v0.2.0 // indirect
-	github.com/onsi/gomega v1.10.0 // indirect
+	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
-	github.com/pkg/errors v0.8.0
+	github.com/pkg/errors v0.9.1
-	github.com/sirupsen/logrus v1.0.5 // indirect
+	github.com/sirupsen/logrus v1.6.0 // indirect
 	github.com/stretchr/testify v1.5.1 // indirect
-	golang.org/x/crypto v0.0.0-20181126163421-e657309f52e7 // indirect
+	golang.org/x/sys v0.0.0-20200515095857-1151b9dac4a9 // indirect
-	gopkg.in/airbrake/gobrake.v2 v2.0.9 // indirect
+	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
-	gopkg.in/gemnasium/logrus-airbrake-hook.v2 v2.1.2 // indirect
+	gopkg.in/yaml.v2 v2.3.0 // indirect
 )

go.sum

@@ -1,58 +1,40 @@
 github.com/asaskevich/EventBus v0.0.0-20180103000110-68a521d7cbbb h1:UgErHX+sTKfxJ1+2IksfX2Jeb2DcSgWN0oqRTUzSg74=
 github.com/asaskevich/EventBus v0.0.0-20180103000110-68a521d7cbbb/go.mod h1:JS7hed4L1fj0hXcyEejnW57/7LCetXggd+vwrRnYeII=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
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+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
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 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.2.4 h1:/eiJrUcujPVeJ3xlSWaiNi3uSVmDGBK1pDHUHAnao1I=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
-gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

mailrelay.json

@@ -2,8 +2,10 @@
 	"smtp_server": "smtp.fastmail.com",
 	"smtp_port": 465,
 	"smtp_starttls": false,
+	"smtp_login_auth_type": false,
 	"smtp_username": "username@fastmail.com",
 	"smtp_password": "secret_app_password",
+	"smtp_skip_cert_verify": false,
 	"local_listen_port": 2525,
 	"local_listen_ip": "0.0.0.0",
 	"allowed_hosts": ["*"]

main.go

@@ -18,8 +18,10 @@ type mailRelayConfig struct {
 	SMTPServer        string   `json:"smtp_server"`
 	SMTPPort          int      `json:"smtp_port"`
 	SMTPStartTLS      bool     `json:"smtp_starttls"`
+	SMTPLoginAuthType bool     `json:"smtp_login_auth_type"`
 	SMTPUsername      string   `json:"smtp_username"`
 	SMTPPassword      string   `json:"smtp_password"`
+	SkipCertVerify    bool     `json:"smtp_skip_cert_verify"`
 	LocalListenIP     string   `json:"local_listen_ip"`
 	LocalListenPort   int      `json:"local_listen_port"`
 	AllowedHosts      []string `json:"allowed_hosts"`
@@ -114,7 +116,13 @@ func sendTest(sender string, rcpt string, port int) error {
 		return err
 	}
 
-	writeBody := func(c *smtp.Client) error {
+	if err := writeBody(conn, sender); err != nil {
+		return err
+	}
+	return conn.Quit()
+}
+
+func writeBody(conn *smtp.Client, sender string) error {
 	wc, err := conn.Data()
 	if err != nil {
 		return err
@@ -123,9 +131,3 @@ func sendTest(sender string, rcpt string, port int) error {
 	_, err = fmt.Fprintf(wc, "From: %s\nSubject: Test message\n\nThis is a test email from mailrelay.\n", sender)
 	return err
 }
-	if err := writeBody(conn); err != nil {
-		return err
-	}
-
-	return conn.Quit()
-}

server.go

@@ -9,9 +9,10 @@ import (
 	"github.com/flashmob/go-guerrilla/mail"
 )
 
+const saveWorkersSize = 3
+
 // Start starts the server.
 func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
-
 	listen := fmt.Sprintf("%s:%d", appConfig.LocalListenIP, appConfig.LocalListenPort)
 
 	logLevel := "info"
@@ -31,7 +32,7 @@ func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
 	cfg.Servers = append(cfg.Servers, sc)
 
 	bcfg := backends.BackendConfig{
-		"save_workers_size":  3,
+		"save_workers_size":     saveWorkersSize,
 		"save_process":          "HeadersParser|Header|Hasher|Debugger|MailRelay",
 		"log_received_mails":    true,
 		"primary_mail_host":     "homeoffice.com",
@@ -40,6 +41,8 @@ func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
 		"smtp_server":           appConfig.SMTPServer,
 		"smtp_port":             appConfig.SMTPPort,
 		"smtp_starttls":         appConfig.SMTPStartTLS,
+		"smtp_login_auth_type":  appConfig.SMTPLoginAuthType,
+		"smtp_skip_cert_verify": appConfig.SkipCertVerify,
 	}
 	cfg.BackendConfig = bcfg
 
@@ -50,11 +53,13 @@ func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
 }
 
 type relayConfig struct {
-	SMTPServer   string `json:"smtp_server"`
+	Server        string `json:"smtp_server"`
-	SMTPPort     int    `json:"smtp_port"`
+	Port          int    `json:"smtp_port"`
 	STARTTLS      bool   `json:"smtp_starttls"`
-	SMTPUsername string `json:"smtp_username"`
+	LoginAuthType bool   `json:"smtp_login_auth_type"`
-	SMTPPassword string `json:"smtp_password"`
+	Username      string `json:"smtp_username"`
+	Password      string `json:"smtp_password"`
+	SkipVerify    bool   `json:"smtp_skip_cert_verify"`
 }
 
 // mailRelayProcessor decorator relays emails to another SMTP server.