Add comments

connection.go

@@ -1065,8 +1065,8 @@ func (c *connection) onReadRequest(r request) error {
 	return nil
 }
 
-// Processes incoming bittorrent messages. The client lock is held upon entry
-// and exit. Returning will end the connection.
+// Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
+// exit. Returning will end the connection.
 func (c *connection) mainReadLoop() (err error) {
 	defer func() {
 		if err != nil {

peer_protocol/msg.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 )
 
+// This is a lazy union representing all the possible fields for messages. Go doesn't have ADTs, and
+// I didn't choose to use type-assertions.
 type Message struct {
 	Keepalive            bool
 	Type                 MessageType