Simple additions to support LMTP

README

@@ -1,10 +1,10 @@
-Smtpd is a Go package for handling the server side of the SMTP protocol.
-It does not handle high level details like what addresses should be
+Smtpd is a Go package for handling the server side of the LMTP & SMTP
+protocol. It does not handle high level details like what addresses should be
 accepted or what should happen with email once it has been fully received;
-those decisions are instead delegated to whatever is driving smtpd.
-Smtpd's purpose is simply to handle the grunt work of a reasonably
-RFC compliant SMTP server, taking care of things like proper command
-sequencing, TLS, and basic correctness of some things.
+those decisions are instead delegated to whatever is driving smtpd. Smtpd's
+purpose is simply to handle the grunt work of a reasonably RFC compliant SMTP
+server, taking care of things like proper command sequencing, TLS, and basic
+correctness of some things.
 
 (The standard library net/smtp package handles only the client side
 of SMTP; it makes no attempt to provide the facilities you'd need to

smtpd.go

@@ -61,6 +61,7 @@ const (
 	HELP
 	AUTH
 	STARTTLS
+	LHLO
 )
 
 // ParsedLine represents a parsed SMTP command line.  Err is set if
@@ -97,6 +98,7 @@ var smtpCommand = []struct {
 }{
 	{HELO, "HELO", canArg},
 	{EHLO, "EHLO", canArg},
+	{LHLO, "LHLO", canArg},
 	{MAILFROM, "MAIL FROM", colonAddress},
 	{RCPTTO, "RCPT TO", colonAddress},
 	{DATA, "DATA", noArg},
@@ -311,6 +313,7 @@ var states = map[Command]struct {
 }{
 	HELO:     {sInitial | sHelo, sHelo},
 	EHLO:     {sInitial | sHelo, sHelo},
+	LHLO:     {sInitial | sHelo, sHelo},
 	AUTH:     {sHelo, sHelo},
 	MAILFROM: {sHelo, sMail},
 	RCPTTO:   {sMail | sRcpt, sRcpt},
@@ -579,7 +582,7 @@ func (c *Conn) Accept() {
 	switch c.curcmd {
 	case HELO:
 		c.reply("250 %s Hello %v", c.Config.LocalName, c.conn.RemoteAddr())
-	case EHLO:
+	case EHLO, LHLO:
 		c.reply("250-%s Hello %v", c.Config.LocalName, c.conn.RemoteAddr())
 		// We advertise 8BITMIME per
 		// http://cr.yp.to/smtp/8bitmime.html
@@ -746,6 +749,58 @@ func (c *Conn) Tempfail() {
 	c.replied = true
 }
 
+// A variant of LmtpRejectMsg suitable for using in the responses to the DATA
+// command in LMTP. It won't advance the state machine, so multiple commands
+// can be issued under control of the caller.
+func (c *Conn) LmtpRejectMsg(format string, elems ...interface{}) {
+	c.RejectMsg(format, elems...)
+	if c.state == sPostData {
+		c.state = sData
+		c.nstate = sPostData
+	}
+	c.replied = false
+}
+
+// A variant of LmtpTempfailMsg suitable for using in the responses to the DATA
+// command in LMTP. It won't advance the state machine, so multiple commands
+// can be issued under control of the caller.
+func (c *Conn) LmtpTempfailMsg(format string, elems ...interface{}) {
+	c.TempfailMsg(format, elems...)
+	if c.state == sPostData {
+		c.state = sData
+		c.nstate = sPostData
+	}
+	c.replied = false
+}
+
+// A variant of LmtpAcceptMsg suitable for using in the responses to the DATA
+// command in LMTP. It won't advance the state machine, so multiple commands
+// can be issued under control of the caller.
+func (c *Conn) LmtpAcceptMsg(format string, elems ...interface{}) {
+	if c.curcmd == DATA {
+		c.replyMulti(250, format, elems...)
+	} else {
+		c.AcceptMsg(format, elems)
+	}
+
+	if c.state == sPostData {
+		c.state = sData
+		c.nstate = sPostData
+	}
+
+	c.replied = false
+}
+
+// Advance the protocol machine and prevent automatic responses, as with LMTP
+// the caller is driving the conversation and should have already replied.
+func (c *Conn) LmtpDataAccept() {
+	if c.replied {
+		return
+	}
+	c.state = c.nstate
+	c.replied = true
+}
+
 // mimeParam() returns true if the parameter argument of a MAIL FROM
 // is what we expect for a client exploiting our advertisement of
 // 8BITMIME.