Fix #244

bep40.go

@@ -3,6 +3,7 @@ package torrent
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"hash/crc32"
 
@@ -53,30 +54,38 @@ func ipv6Mask(a, b net.IP) net.IPMask {
 	panic(fmt.Sprintf("%s %s", a, b))
 }
 
-func bep40PriorityBytes(a, b ipPort) []byte {
+func bep40PriorityBytes(a, b ipPort) ([]byte, error) {
 	if a.IP.Equal(b.IP) {
 		var ret [4]byte
 		binary.BigEndian.PutUint16(ret[0:2], a.Port)
 		binary.BigEndian.PutUint16(ret[2:4], b.Port)
-		return ret[:]
+		return ret[:], nil
 	}
 	if a4, b4 := a.IP.To4(), b.IP.To4(); a4 != nil && b4 != nil {
 		m := ipv4Mask(a.IP, b.IP)
-		return append(a4.Mask(m), b4.Mask(m)...)
+		return append(a4.Mask(m), b4.Mask(m)...), nil
 	}
 	if a6, b6 := a.IP.To16(), b.IP.To16(); a6 != nil && b6 != nil {
 		m := ipv6Mask(a.IP, b.IP)
-		return append(a6.Mask(m), b6.Mask(m)...)
+		return append(a6.Mask(m), b6.Mask(m)...), nil
 	}
-	panic(fmt.Sprintf("%s %s", a.IP, b.IP))
+	return nil, errors.New("incomparable IPs")
 }
 
-func bep40Priority(a, b ipPort) peerPriority {
-	bs := bep40PriorityBytes(a, b)
+func bep40Priority(a, b ipPort) (peerPriority, error) {
+	bs, err := bep40PriorityBytes(a, b)
+	if err != nil {
+		return 0, nil
+	}
 	i := len(bs) / 2
 	_a, _b := bs[:i], bs[i:]
 	if bytes.Compare(_a, _b) > 0 {
 		bs = append(_b, _a...)
 	}
-	return crc32.Checksum(bs, table)
+	return crc32.Checksum(bs, table), nil
+}
+
+func bep40PriorityIgnoreError(a, b ipPort) peerPriority {
+	prio, _ := bep40Priority(a, b)
+	return prio
 }

bep40_test.go

@@ -8,20 +8,24 @@ import (
 )
 
 func TestBep40Priority(t *testing.T) {
-	assert.EqualValues(t, 0xec2d7224, bep40Priority(
+	assert.EqualValues(t, 0xec2d7224, bep40PriorityIgnoreError(
 		ipPort{net.ParseIP("123.213.32.10"), 0},
 		ipPort{net.ParseIP("98.76.54.32"), 0},
 	))
-	assert.EqualValues(t, 0xec2d7224, bep40Priority(
+	assert.EqualValues(t, 0xec2d7224, bep40PriorityIgnoreError(
 		ipPort{net.ParseIP("98.76.54.32"), 0},
 		ipPort{net.ParseIP("123.213.32.10"), 0},
 	))
-	assert.Equal(t, peerPriority(0x99568189), bep40Priority(
+	assert.Equal(t, peerPriority(0x99568189), bep40PriorityIgnoreError(
 		ipPort{net.ParseIP("123.213.32.10"), 0},
 		ipPort{net.ParseIP("123.213.32.234"), 0},
 	))
-	assert.EqualValues(t, "\x00\x00\x00\x00", bep40PriorityBytes(
-		ipPort{net.ParseIP("123.213.32.234"), 0},
-		ipPort{net.ParseIP("123.213.32.234"), 0},
-	))
+	assert.EqualValues(t, "\x00\x00\x00\x00", func() []byte {
+		b, _ := bep40PriorityBytes(
+			ipPort{net.ParseIP("123.213.32.234"), 0},
+			ipPort{net.ParseIP("123.213.32.234"), 0},
+		)
+		return b
+	}())
+
 }

client.go

@@ -945,7 +945,7 @@ func (cl *Client) newTorrent(ih metainfo.Hash, specStorage storage.ClientImpl) (
 		peers: prioritizedPeers{
 			om: btree.New(2),
 			getPrio: func(p Peer) peerPriority {
-				return bep40Priority(cl.publicAddr(p.IP), p.addr())
+				return bep40PriorityIgnoreError(cl.publicAddr(p.IP), p.addr())
 			},
 		},
 		conns: make(map[*connection]struct{}, 2*cl.config.EstablishedConnsPerTorrent),