From 5da71dab4aef6ee95e3994a5be9644a91423f9fe Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Mon, 2 Jan 2017 01:32:26 -0500
Subject: [PATCH] Implement the POP3 UIDL command.

---
 pop3.go           |  5 +++++
 pop3/conn.go      | 25 +++++++++++++++++++++++++
 pop3/conn_test.go | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 pop3/server.go    |  1 +
 4 files changed, 78 insertions(+)

diff --git a/pop3.go b/pop3.go
index c803143..dc476d4 100644
--- a/pop3.go
+++ b/pop3.go
@@ -126,6 +126,11 @@ type message struct {
 	deleted  bool
 }
 
+func (m message) UniqueID() string {
+	l := len(m.filename)
+	return path.Base(m.filename[:l-len(".msg")])
+}
+
 func (m message) ID() int {
 	return m.index + 1
 }
diff --git a/pop3/conn.go b/pop3/conn.go
index b16dcc4..1eecd0a 100644
--- a/pop3/conn.go
+++ b/pop3/conn.go
@@ -90,6 +90,8 @@ func AcceptConnection(netConn net.Conn, po PostOffice, log zap.Logger) {
 			conn.ok("")
 		case "RSET":
 			conn.doRSET()
+		case "UIDL":
+			conn.doUIDL()
 		default:
 			conn.log.Error("unknown command")
 			conn.err("unknown command")
@@ -267,6 +269,29 @@ func (conn *connection) doRSET() {
 	conn.ok("")
 }
 
+func (conn *connection) doUIDL() {
+	if conn.state != stateTxn {
+		conn.err(errStateTxn)
+		return
+	}
+
+	msgs, err := conn.mb.ListMessages()
+	if err != nil {
+		conn.log.Error("failed to list messages", zap.Error(err))
+		conn.err(err.Error())
+		return
+	}
+
+	conn.ok("unique-id listing")
+	for _, msg := range msgs {
+		if msg.Deleted() {
+			continue
+		}
+		conn.tp.PrintfLine("%d %s", msg.ID(), msg.UniqueID())
+	}
+	conn.tp.PrintfLine(".")
+}
+
 func (conn *connection) getRequestedMessage() Message {
 	var cmd string
 	var idx int
diff --git a/pop3/conn_test.go b/pop3/conn_test.go
index 4671bca..4d25a39 100644
--- a/pop3/conn_test.go
+++ b/pop3/conn_test.go
@@ -129,6 +129,10 @@ type testMessage struct {
 	body    string
 }
 
+func (m *testMessage) UniqueID() string {
+	return fmt.Sprintf("%p", m)
+}
+
 func (m *testMessage) ID() int {
 	return m.id
 }
@@ -297,6 +301,10 @@ func TestRetr(t *testing.T) {
 		{"STAT", responseOK},
 		{"RETR 1", func(t testing.TB, tp *textproto.Conn) string {
 			responseOK(t, tp)
+			if t.Failed() {
+				return ""
+			}
+
 			resp, err := tp.ReadDotLines()
 			if err != nil {
 				t.Error(err)
@@ -312,6 +320,10 @@ func TestRetr(t *testing.T) {
 		}},
 		{"RETR 2", func(t testing.TB, tp *textproto.Conn) string {
 			responseOK(t, tp)
+			if t.Failed() {
+				return ""
+			}
+
 			resp, err := tp.ReadDotLines()
 			if err != nil {
 				t.Error(err)
@@ -328,3 +340,38 @@ func TestRetr(t *testing.T) {
 		{"QUIT", responseOK},
 	})
 }
+
+func TestUidl(t *testing.T) {
+	s := newTestServer()
+	s.mb.msgs[1] = &testMessage{1, 3, false, "abc"}
+	s.mb.msgs[2] = &testMessage{2, 1, true, "Z"}
+	s.mb.msgs[3] = &testMessage{3, 4, false, "test"}
+
+	clientServerTest(t, s, []requestResponse{
+		{"USER u", responseOK},
+		{"PASS p", responseOK},
+		{"UIDL", func(t testing.TB, tp *textproto.Conn) string {
+			responseOK(t, tp)
+			if t.Failed() {
+				return ""
+			}
+
+			resp, err := tp.ReadDotLines()
+			if err != nil {
+				t.Error(err)
+				return ""
+			}
+
+			expected := []string{
+				fmt.Sprintf("1 %p", s.mb.msgs[1]),
+				fmt.Sprintf("3 %p", s.mb.msgs[3]),
+			}
+			if !reflect.DeepEqual(resp, expected) {
+				t.Errorf("Expected %v, got %v", expected, resp)
+			}
+
+			return ""
+		}},
+		{"QUIT", responseOK},
+	})
+}
diff --git a/pop3/server.go b/pop3/server.go
index 6e5dc36..5ff787e 100644
--- a/pop3/server.go
+++ b/pop3/server.go
@@ -5,6 +5,7 @@ import (
 )
 
 type Message interface {
+	UniqueID() string
 	ID() int
 	Size() int
 	Deleted() bool
-- 
2.22.5