From 75177984b27f158dff6838972d06aff1acf2bcec Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Mon, 12 Dec 2016 21:31:41 -0500
Subject: [PATCH] Add the first test for SMTP connections, based on the
 exchange in RFC 5321.

This fixes a few bugs caught by the test.
---
 smtp/conn.go      |   3 +-
 smtp/conn_test.go | 108 ++++++++++++++++++++++++++++++++++++++++++++++
 smtp/server.go    |  14 ++++++
 3 files changed, 124 insertions(+), 1 deletion(-)
 create mode 100644 smtp/conn_test.go

diff --git a/smtp/conn.go b/smtp/conn.go
index f29b198..ac07595 100644
--- a/smtp/conn.go
+++ b/smtp/conn.go
@@ -41,7 +41,7 @@ func AcceptConnection(netConn net.Conn, server Server) error {
 
 	var err error
 
-	conn.writeReply(250, fmt.Sprintf("%s ESMTP [%s] (mailpopbox)", server.Name(), netConn.LocalAddr()))
+	conn.writeReply(220, fmt.Sprintf("%s ESMTP [%s] (mailpopbox)", server.Name(), netConn.LocalAddr()))
 
 	for {
 		conn.line, err = conn.tp.ReadLine()
@@ -58,6 +58,7 @@ func AcceptConnection(netConn net.Conn, server Server) error {
 
 		switch cmd {
 		case "QUIT":
+			conn.writeReply(221, "Goodbye")
 			conn.tp.Close()
 			break
 		case "HELO":
diff --git a/smtp/conn_test.go b/smtp/conn_test.go
new file mode 100644
index 0000000..d0998cd
--- /dev/null
+++ b/smtp/conn_test.go
@@ -0,0 +1,108 @@
+package smtp
+
+import (
+	"net"
+	"net/textproto"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func ok(t testing.TB, err error) {
+	if err != nil {
+		_, file, line, _ := runtime.Caller(1)
+		t.Errorf("[%s:%d] unexpected error: %v", filepath.Base(file), line, err)
+	}
+}
+
+func readCodeLine(t testing.TB, conn *textproto.Conn, code int) string {
+	_, message, err := conn.ReadCodeLine(code)
+	ok(t, err)
+	return message
+}
+
+// runServer creates a TCP socket, runs a listening server, and returns the connection.
+// The server exits when the Conn is closed.
+func runServer(t *testing.T, server Server) net.Listener {
+	l, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		t.Fatal(err)
+		return nil
+	}
+
+	go func() {
+		for {
+			conn, err := l.Accept()
+			if err != nil {
+				return
+			}
+			go AcceptConnection(conn, server)
+		}
+	}()
+
+	return l
+}
+
+type testServer struct {
+	EmptyServerCallbacks
+}
+
+func (s *testServer) Name() string {
+	return "Test-Server"
+}
+
+func createClient(t *testing.T, addr net.Addr) *textproto.Conn {
+	conn, err := textproto.Dial(addr.Network(), addr.String())
+	if err != nil {
+		t.Fatal(err)
+		return nil
+	}
+	return conn
+}
+
+// RFC 5321 § D.1
+func TestScenarioTypical(t *testing.T) {
+	s := testServer{}
+	l := runServer(t, &s)
+	defer l.Close()
+
+	conn := createClient(t, l.Addr())
+
+	message := readCodeLine(t, conn, 220)
+	if !strings.HasPrefix(message, s.Name()) {
+		t.Errorf("Greeting does not have server name, got %q", message)
+	}
+
+	greet := "greeting.TestScenarioTypical"
+	ok(t, conn.PrintfLine("EHLO "+greet))
+
+	_, message, err := conn.ReadResponse(250)
+	ok(t, err)
+	if !strings.Contains(message, greet) {
+		t.Errorf("EHLO response does not contain greeting, got %q", message)
+	}
+
+	ok(t, conn.PrintfLine("MAIL FROM:<Smith@bar.com>"))
+	readCodeLine(t, conn, 250)
+
+	ok(t, conn.PrintfLine("RCPT TO:<Jones@foo.com>"))
+	readCodeLine(t, conn, 250)
+
+	ok(t, conn.PrintfLine("RCPT TO:<Green@foo.com>"))
+	readCodeLine(t, conn, 250) // TODO: make this 55o by rejecting Green
+
+	ok(t, conn.PrintfLine("RCPT TO:<Brown@foo.com>"))
+	readCodeLine(t, conn, 250)
+
+	ok(t, conn.PrintfLine("DATA"))
+	readCodeLine(t, conn, 354)
+
+	ok(t, conn.PrintfLine("Blah blah blah..."))
+	ok(t, conn.PrintfLine("...etc. etc. etc."))
+	ok(t, conn.PrintfLine("."))
+	readCodeLine(t, conn, 250)
+
+	ok(t, conn.PrintfLine("QUIT"))
+	readCodeLine(t, conn, 221)
+}
diff --git a/smtp/server.go b/smtp/server.go
index 271e172..3ecb24a 100644
--- a/smtp/server.go
+++ b/smtp/server.go
@@ -31,3 +31,17 @@ type Server interface {
 	OnEHLO() *ReplyLine
 	OnMessageDelivered(Envelope) *ReplyLine
 }
+
+type EmptyServerCallbacks struct {}
+
+func (*EmptyServerCallbacks) TLSConfig() *tls.Config {
+	return nil
+}
+
+func (*EmptyServerCallbacks) OnEHLO() *ReplyLine {
+	return nil
+}
+
+func (*EmptyServerCallbacks) OnMessageDelivered(Envelope) *ReplyLine {
+	return nil
+}
-- 
2.43.5