From 98d5a19d503894b1743b4be6f578a8c2e49f4561 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Mon, 5 Dec 2022 17:53:36 +1100
Subject: [PATCH] Support marshalling http tracker response peers

---
 tracker/http/http.go      |  4 ++--
 tracker/http/http_test.go | 14 +++++++-------
 tracker/http/peer.go      |  6 +++---
 tracker/http/protocol.go  | 33 +++++++++++++++++++++++++++++----
 4 files changed, 41 insertions(+), 16 deletions(-)

diff --git a/tracker/http/http.go b/tracker/http/http.go
index 9aa53797..a7022a5f 100644
--- a/tracker/http/http.go
+++ b/tracker/http/http.go
@@ -133,10 +133,10 @@ func (cl Client) Announce(ctx context.Context, ar AnnounceRequest, opt AnnounceO
 	ret.Interval = trackerResponse.Interval
 	ret.Leechers = trackerResponse.Incomplete
 	ret.Seeders = trackerResponse.Complete
-	if len(trackerResponse.Peers) != 0 {
+	if len(trackerResponse.Peers.List) != 0 {
 		vars.Add("http responses with nonempty peers key", 1)
 	}
-	ret.Peers = trackerResponse.Peers
+	ret.Peers = trackerResponse.Peers.List
 	if len(trackerResponse.Peers6) != 0 {
 		vars.Add("http responses with nonempty peers6 key", 1)
 	}
diff --git a/tracker/http/http_test.go b/tracker/http/http_test.go
index 329aed72..7fd98a5d 100644
--- a/tracker/http/http_test.go
+++ b/tracker/http/http_test.go
@@ -22,12 +22,12 @@ func TestUnmarshalHTTPResponsePeerDicts(t *testing.T) {
 			"e"),
 		&hr))
 
-	require.Len(t, hr.Peers, 2)
-	assert.Equal(t, []byte("thisisthe20bytepeeri"), hr.Peers[0].ID)
-	assert.EqualValues(t, 9999, hr.Peers[0].Port)
-	assert.EqualValues(t, 9998, hr.Peers[1].Port)
-	assert.NotNil(t, hr.Peers[0].IP)
-	assert.NotNil(t, hr.Peers[1].IP)
+	require.Len(t, hr.Peers.List, 2)
+	assert.Equal(t, []byte("thisisthe20bytepeeri"), hr.Peers.List[0].ID)
+	assert.EqualValues(t, 9999, hr.Peers.List[0].Port)
+	assert.EqualValues(t, 9998, hr.Peers.List[1].Port)
+	assert.NotNil(t, hr.Peers.List[0].IP)
+	assert.NotNil(t, hr.Peers.List[1].IP)
 
 	assert.Len(t, hr.Peers6, 1)
 	assert.EqualValues(t, "1234123412341234", hr.Peers6[0].IP)
@@ -40,7 +40,7 @@ func TestUnmarshalHttpResponseNoPeers(t *testing.T) {
 		[]byte("d6:peers618:123412341234123456e"),
 		&hr,
 	))
-	require.Len(t, hr.Peers, 0)
+	require.Len(t, hr.Peers.List, 0)
 	assert.Len(t, hr.Peers6, 1)
 }
 
diff --git a/tracker/http/peer.go b/tracker/http/peer.go
index 076a88c6..363ba6d3 100644
--- a/tracker/http/peer.go
+++ b/tracker/http/peer.go
@@ -8,9 +8,9 @@ import (
 )
 
 type Peer struct {
-	IP   net.IP
-	Port int
-	ID   []byte
+	IP   net.IP `bencode:"ip"`
+	Port int    `bencode:"port"`
+	ID   []byte `bencode:"peer id"`
 }
 
 func (p Peer) String() string {
diff --git a/tracker/http/protocol.go b/tracker/http/protocol.go
index 5ce9fa90..11a90b2a 100644
--- a/tracker/http/protocol.go
+++ b/tracker/http/protocol.go
@@ -19,7 +19,30 @@ type HttpResponse struct {
 	Peers6 krpc.CompactIPv6NodeAddrs `bencode:"peers6"`
 }
 
-type Peers []Peer
+type Peers struct {
+	List    []Peer
+	Compact bool
+}
+
+func (me Peers) MarshalBencode() ([]byte, error) {
+	if me.Compact {
+		cnas := make([]krpc.NodeAddr, 0, len(me.List))
+		for _, peer := range me.List {
+			cnas = append(cnas, krpc.NodeAddr{
+				IP:   peer.IP,
+				Port: peer.Port,
+			})
+		}
+		return krpc.CompactIPv4NodeAddrs(cnas).MarshalBencode()
+	} else {
+		return bencode.Marshal(me.List)
+	}
+}
+
+var (
+	_ bencode.Unmarshaler = (*Peers)(nil)
+	_ bencode.Marshaler   = Peers{}
+)
 
 func (me *Peers) UnmarshalBencode(b []byte) (err error) {
 	var _v interface{}
@@ -35,19 +58,21 @@ func (me *Peers) UnmarshalBencode(b []byte) (err error) {
 		if err != nil {
 			return
 		}
+		me.Compact = true
 		for _, cp := range cnas {
-			*me = append(*me, Peer{
+			me.List = append(me.List, Peer{
 				IP:   cp.IP[:],
-				Port: int(cp.Port),
+				Port: cp.Port,
 			})
 		}
 		return
 	case []interface{}:
 		vars.Add("http responses with list peers", 1)
+		me.Compact = false
 		for _, i := range v {
 			var p Peer
 			p.FromDictInterface(i.(map[string]interface{}))
-			*me = append(*me, p)
+			me.List = append(me.List, p)
 		}
 		return
 	default:
-- 
2.48.1