Merge branch 'master' into case-insensitive

README.md

@@ -71,6 +71,11 @@ func (bkd *Backend) Login(username, password string) (smtp.User, error) {
 	return &User{}, nil
 }
 
+// Require clients to authenticate using SMTP AUTH before sending emails
+func (bkd *Backend) AnonymousLogin() (smtp.User, error) {
+	return nil, smtp.ErrAuthRequired
+}
+
 type User struct{}
 
 func (u *User) Send(from string, to []string, r io.Reader) error {

backend.go

@@ -1,13 +1,24 @@
 package smtp
 
 import (
+	"errors"
 	"io"
 )
 
+var (
+	ErrAuthRequired = errors.New("Please authenticate first")
+	ErrAuthUnsupported = errors.New("Authentication not supported")
+)
+
 // A SMTP server backend.
 type Backend interface {
-	// Authenticate a user.
+	// Authenticate a user. Return smtp.ErrAuthUnsupported if you don't want to
+	// support this.
 	Login(username, password string) (User, error)
+
+	// Called if the client attempts to send mail without logging in first.
+	// Return smtp.ErrAuthRequired if you don't want to support this.
+	AnonymousLogin() (User, error)
 }
 
 // An authenticated user.

conn.go

@@ -5,9 +5,9 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net"
 	"net/textproto"
-	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -63,6 +63,16 @@ func (c *Conn) init() {
 	c.text = textproto.NewConn(rwc)
 }
 
+func (c *Conn) unrecognizedCommand(cmd string) {
+	c.WriteResponse(500, fmt.Sprintf("Syntax error, %v command unrecognized", cmd))
+
+	c.nbrErrors++
+	if c.nbrErrors > 3 {
+		c.WriteResponse(500, "Too many unrecognized commands")
+		c.Close()
+	}
+}
+
 // Commands are dispatched to the appropriate handler functions.
 func (c *Conn) handle(cmd string, arg string) {
 	if cmd == "" {
@@ -74,8 +84,16 @@ func (c *Conn) handle(cmd string, arg string) {
 	case "SEND", "SOML", "SAML", "EXPN", "HELP", "TURN":
 		// These commands are not implemented in any state
 		c.WriteResponse(502, fmt.Sprintf("%v command not implemented", cmd))
-	case "HELO", "EHLO":
-		c.handleGreet((cmd == "EHLO"), arg)
+	case "HELO", "EHLO", "LHLO":
+		lmtp := cmd == "LHLO"
+		enhanced := lmtp || cmd == "EHLO"
+		if c.server.LMTP && !lmtp {
+			c.WriteResponse(500, "This is a LMTP server, use LHLO")
+		}
+		if !c.server.LMTP && lmtp {
+			c.WriteResponse(500, "This is not a LMTP server")
+		}
+		c.handleGreet(enhanced, arg)
 	case "MAIL":
 		c.handleMail(arg)
 	case "RCPT":
@@ -93,17 +111,15 @@ func (c *Conn) handle(cmd string, arg string) {
 		c.WriteResponse(221, "Goodnight and good luck")
 		c.Close()
 	case "AUTH":
-		c.handleAuth(arg)
+		if c.server.AuthDisabled {
+			c.unrecognizedCommand(cmd)
+		} else {
+			c.handleAuth(arg)
+		}
 	case "STARTTLS":
 		c.handleStartTLS()
 	default:
-		c.WriteResponse(500, fmt.Sprintf("Syntax error, %v command unrecognized", cmd))
-
-		c.nbrErrors++
-		if c.nbrErrors > 3 {
-			c.WriteResponse(500, "Too many unrecognized commands")
-			c.Close()
-		}
+		c.unrecognizedCommand(cmd)
 	}
 }
 
@@ -117,10 +133,12 @@ func (c *Conn) User() User {
 	return c.user
 }
 
+// Setting the user resets any message beng generated
 func (c *Conn) SetUser(user User) {
 	c.locker.Lock()
 	defer c.locker.Unlock()
 	c.user = user
+	c.msg = &message{}
 }
 
 func (c *Conn) Close() error {
@@ -137,6 +155,11 @@ func (c *Conn) IsTLS() bool {
 	return ok
 }
 
+func (c *Conn) authAllowed() bool {
+	return !c.server.AuthDisabled &&
+		(c.IsTLS() || c.server.AllowInsecureAuth)
+}
+
 // GREET state -> waiting for HELO
 func (c *Conn) handleGreet(enhanced bool, arg string) {
 	if !enhanced {
@@ -162,7 +185,7 @@ func (c *Conn) handleGreet(enhanced bool, arg string) {
 		if c.server.TLSConfig != nil && !c.IsTLS() {
 			caps = append(caps, "STARTTLS")
 		}
-		if c.IsTLS() || c.server.AllowInsecureAuth {
+		if c.authAllowed() {
 			authCap := "AUTH"
 			for name, _ := range c.server.auths {
 				authCap += " " + name
@@ -186,26 +209,38 @@ func (c *Conn) handleMail(arg string) {
 		c.WriteResponse(502, "Please introduce yourself first.")
 		return
 	}
-	if c.msg == nil {
-		c.WriteResponse(502, "Please authenticate first.")
-		return
+
+	if c.User() == nil {
+		user, err := c.server.Backend.AnonymousLogin()
+		if err != nil {
+			c.WriteResponse(502, err.Error())
+			return
+		}
+
+		c.SetUser(user)
 	}
 
-	// Match FROM, while accepting '>' as quoted pair and in double quoted strings
-	// (?i) makes the regex case insensitive, (?:) is non-grouping sub-match
-	re := regexp.MustCompile("(?i)^FROM:\\s*<((?:\\\\>|[^>])+|\"[^\"]+\"@[^>]+)>( [\\w= ]+)?$")
-	m := re.FindStringSubmatch(arg)
-	if m == nil {
+	if len(arg) < 6 || strings.ToUpper(arg[0:5]) != "FROM:" {
+		c.WriteResponse(501, "Was expecting MAIL arg syntax of FROM:<address>")
+		return
+	}
+	fromArgs := strings.Split(strings.Trim(arg[5:], " "), " ")
+	if c.server.Strict {
+		if !strings.HasPrefix(fromArgs[0], "<") || !strings.HasSuffix(fromArgs[0], ">") {
+			c.WriteResponse(501, "Was expecting MAIL arg syntax of FROM:<address>")
+			return
+		}
+	}
+	from := strings.Trim(fromArgs[0], "<> ")
+	if from == "" {
 		c.WriteResponse(501, "Was expecting MAIL arg syntax of FROM:<address>")
 		return
 	}
-
-	from := m[1]
 
 	// This is where the Conn may put BODY=8BITMIME, but we already
 	// read the DATA as bytes, so it does not effect our processing.
-	if m[2] != "" {
-		args, err := parseArgs(m[2])
+	if len(fromArgs) > 1 {
+		args, err := parseArgs(fromArgs[1:])
 		if err != nil {
 			c.WriteResponse(501, "Unable to parse MAIL ESMTP parameters")
 			return
@@ -315,10 +350,8 @@ func (c *Conn) handleAuth(arg string) {
 		}
 	}
 
-	if c.User != nil {
+	if c.User() != nil {
 		c.WriteResponse(235, "Authentication succeeded")
-
-		c.msg = &message{}
 	}
 }
 
@@ -365,15 +398,33 @@ func (c *Conn) handleData(arg string) {
 	// We have recipients, go to accept data
 	c.WriteResponse(354, "Go ahead. End your data with <CR><LF>.<CR><LF>")
 
+	var (
+		code int
+		msg string
+	)
 	c.msg.Reader = newDataReader(c)
-	if err := c.User().Send(c.msg.From, c.msg.To, c.msg.Reader); err != nil {
+	err := c.User().Send(c.msg.From, c.msg.To, c.msg.Reader)
+	io.Copy(ioutil.Discard, c.msg.Reader) // Make sure all the data has been consumed
+	if err != nil {
 		if smtperr, ok := err.(*smtpError); ok {
-			c.WriteResponse(smtperr.Code, smtperr.Message)
+			code = smtperr.Code
+			msg = smtperr.Message
 		} else {
-			c.WriteResponse(554, "Error: transaction failed, blame it on the weather: "+err.Error())
+			code = 554
+			msg = "Error: transaction failed, blame it on the weather: " + err.Error()
+		}
+	} else {
+		code = 250
+		msg = "OK: queued"
+	}
+
+	if c.server.LMTP {
+		// TODO: support per-recipient responses
+		for _, rcpt := range c.msg.To {
+			c.WriteResponse(code, "<" + rcpt + "> " + msg)
 		}
 	} else {
-		c.WriteResponse(250, "Ok: queued")
+		c.WriteResponse(code, msg)
 	}
 
 	c.reset()
@@ -418,13 +469,13 @@ func (c *Conn) ReadLine() (string, error) {
 }
 
 func (c *Conn) reset() {
-	if user := c.User(); user != nil {
-		user.Logout()
+	c.locker.Lock()
+	defer c.locker.Unlock()
+
+	if c.user != nil {
+		c.user.Logout()
 	}
 
-	c.locker.Lock()
-	c.helo = ""
 	c.user = nil
 	c.msg = nil
-	c.locker.Unlock()
 }

go.mod

@@ -0,0 +1,3 @@
+module github.com/emersion/go-smtp
+
+require github.com/emersion/go-sasl v0.0.0-20161116183048-7e096a0a6197

parse.go

@@ -2,7 +2,6 @@ package smtp
 
 import (
 	"fmt"
-	"regexp"
 	"strings"
 )
 
@@ -40,18 +39,19 @@ func parseCmd(line string) (cmd string, arg string, err error) {
 // string:
 //		" BODY=8BITMIME SIZE=1024"
 // The leading space is mandatory.
-func parseArgs(arg string) (args map[string]string, err error) {
-	args = map[string]string{}
-	re := regexp.MustCompile(" (\\w+)=(\\w+)")
-	pm := re.FindAllStringSubmatch(arg, -1)
-	if pm == nil {
-		return nil, fmt.Errorf("Failed to parse arg string: %q")
+func parseArgs(args []string) (map[string]string, error) {
+	argMap := map[string]string{}
+	for _, arg := range args {
+		if arg == "" {
+			continue
+		}
+		m := strings.Split(arg, "=")
+		if len(m) != 2 {
+			return nil, fmt.Errorf("Failed to parse arg string: %q", arg)
+		}
+		argMap[strings.ToUpper(m[0])] = m[1]
 	}
-
-	for _, m := range pm {
-		args[strings.ToUpper(m[1])] = m[2]
-	}
-	return args, nil
+	return argMap, nil
 }
 
 func parseHelloArgument(arg string) (string, error) {

server.go

@@ -10,6 +10,8 @@ import (
 	"github.com/emersion/go-sasl"
 )
 
+var errTCPAndLMTP = errors.New("smtp: cannot start LMTP server listening on a TCP socket")
+
 // A function that creates SASL servers.
 type SaslServerFactory func(conn *Conn) sasl.Server
 
@@ -19,14 +21,22 @@ type Server struct {
 	Addr string
 	// The server TLS configuration.
 	TLSConfig *tls.Config
+	// Enable LMTP mode, as defined in RFC 2033. LMTP mode cannot be used with a
+	// TCP listener.
+	LMTP bool
 
 	Domain            string
 	MaxRecipients     int
 	MaxIdleSeconds    int
 	MaxMessageBytes   int
 	AllowInsecureAuth bool
+	Strict            bool
 	Debug             io.Writer
 
+	// If set, the AUTH command will not be advertised and authentication
+	// attempts will be rejected. This setting overrides AllowInsecureAuth.
+	AuthDisabled bool
+
 	// The server backend.
 	Backend Backend
 
@@ -126,6 +136,10 @@ func (s *Server) handleConn(c *Conn) error {
 //
 // If s.Addr is blank, ":smtp" is used.
 func (s *Server) ListenAndServe() error {
+	if s.LMTP {
+		return errTCPAndLMTP
+	}
+
 	addr := s.Addr
 	if addr == "" {
 		addr = ":smtp"
@@ -144,6 +158,10 @@ func (s *Server) ListenAndServe() error {
 //
 // If s.Addr is blank, ":smtps" is used.
 func (s *Server) ListenAndServeTLS() error {
+	if s.LMTP {
+		return errTCPAndLMTP
+	}
+
 	addr := s.Addr
 	if addr == "" {
 		addr = ":smtps"
@@ -157,6 +175,17 @@ func (s *Server) ListenAndServeTLS() error {
 	return s.Serve(l)
 }
 
+// ListenAndServeUnix listens on a Unix address and then calls Serve to handle
+// requests on incoming connections.
+func (s *Server) ListenAndServeUnix(addr *net.UnixAddr) error {
+	l, err := net.ListenUnix("unix", addr)
+	if err != nil {
+		return err
+	}
+
+	return s.Serve(l)
+}
+
 // Close stops the server.
 func (s *Server) Close() {
 	s.listener.Close()