Run go vet on everything

client.go

@@ -717,7 +717,7 @@ func (me *Client) connectionLoop(t *torrent, c *connection) error {
 					log.Printf("added %d peers from PEX", len(pexMsg.Added))
 				}()
 			default:
-				err = fmt.Errorf("unexpected extended message ID: %s", msg.ExtendedID)
+				err = fmt.Errorf("unexpected extended message ID: %v", msg.ExtendedID)
 			}
 		default:
 			err = fmt.Errorf("received unknown message type: %#v", msg.Type)

client_test.go

@@ -41,7 +41,7 @@ func TestTorrentInitialState(t *testing.T) {
 	}
 	p := tor.Pieces[0]
 	if len(p.PendingChunkSpecs) != 1 {
-		t.Fatalf("should only be 1 chunk: %s", p.PendingChunkSpecs)
+		t.Fatalf("should only be 1 chunk: %v", p.PendingChunkSpecs)
 	}
 	if _, ok := p.PendingChunkSpecs[chunkSpec{
 		Length: 13,

dht/closest_nodes.go

@@ -23,7 +23,7 @@ func (me *nodeMaxHeap) Push(val interface{}) {
 	me.IDs = append(me.IDs, val.(string))
 }
 func (me nodeMaxHeap) Swap(i, j int) {
-	me.IDs[i], me.IDs[j] = me.IDs[i], me.IDs[j]
+	me.IDs[i], me.IDs[j] = me.IDs[j], me.IDs[i]
 }
 
 type closestNodesSelector struct {

tracker/udp/udp_tracker.go

@@ -124,7 +124,6 @@ func (c *client) Announce(req *tracker.AnnounceRequest) (res tracker.AnnounceRes
 			Port: int(p.Port),
 		})
 	}
-	return
 }
 
 func (c *client) write(h *RequestHeader, body interface{}) (err error) {