From cf3806cb9b28cc855c86d4576c02a21df745f256 Mon Sep 17 00:00:00 2001
From: Jimmy Zelinskie <jimmyzelinskie@gmail.com>
Date: Mon, 6 Apr 2015 19:06:06 -0400
Subject: [PATCH] udp: handleOptionalParameters method added

This also addresses an issue where the goroutine was not breaking out of
the loop parsing the options, instead it was only breaking out of the
switch statement.
---
 udp/protocol.go | 47 ++++++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/udp/protocol.go b/udp/protocol.go
index c236e79..20986c4 100644
--- a/udp/protocol.go
+++ b/udp/protocol.go
@@ -150,15 +150,34 @@ func (s *Server) newAnnounce(packet []byte, ip net.IP) (*models.Announce, error)
 	numWant := binary.BigEndian.Uint32(packet[92:96])
 	port := binary.BigEndian.Uint16(packet[96:98])
 
-	// Optionally, parse the optional parameteres as described in BEP41.
-	var IPv6Endpoint models.Endpoint
+	announce := &models.Announce{
+		Config:     s.config,
+		Downloaded: downloaded,
+		Event:      eventIDs[eventID],
+		IPv4: models.Endpoint{
+			IP:   ip,
+			Port: port,
+		},
+		Infohash: string(infohash),
+		Left:     left,
+		NumWant:  int(numWant),
+		PeerID:   string(peerID),
+		Uploaded: uploaded,
+	}
+
+	return s.handleOptionalParameters(packet, announce)
+}
+
+// HandleOptionalParameters parses the optional parameters as described in BEP41
+// and updates an announce with the values parsed.
+func (s *Server) handleOptionalParameters(packet []byte, announce *models.Announce) (*models.Announce, error) {
 	if len(packet) > 98 {
 		optionStartIndex := 98
 		for optionStartIndex < len(packet)-1 {
 			option := packet[optionStartIndex]
 			switch option {
 			case optionEndOfOptions:
-				break
+				return announce, nil
 
 			case optionNOP:
 				optionStartIndex++
@@ -184,9 +203,9 @@ func (s *Server) newAnnounce(packet []byte, ip net.IP) (*models.Announce, error)
 
 				ipv6bytes := packet[optionStartIndex+1 : optionStartIndex+17]
 				if s.config.AllowIPSpoofing && !bytes.Equal(ipv6bytes, emptyIPv6) {
-					IPv6Endpoint.IP = net.ParseIP(string(ipv6bytes)).To16()
-					IPv6Endpoint.Port = binary.BigEndian.Uint16(packet[optionStartIndex+17 : optionStartIndex+19])
-					if IPv6Endpoint.IP == nil {
+					announce.IPv6.IP = net.ParseIP(string(ipv6bytes)).To16()
+					announce.IPv6.Port = binary.BigEndian.Uint16(packet[optionStartIndex+17 : optionStartIndex+19])
+					if announce.IPv6.IP == nil {
 						return nil, errMalformedIP
 					}
 				}
@@ -194,23 +213,13 @@ func (s *Server) newAnnounce(packet []byte, ip net.IP) (*models.Announce, error)
 				optionStartIndex += 19
 
 			default:
-				break
+				return announce, nil
 			}
 		}
 	}
 
-	return &models.Announce{
-		Config:     s.config,
-		Downloaded: downloaded,
-		Event:      eventIDs[eventID],
-		IPv4:       models.Endpoint{ip, port},
-		IPv6:       IPv6Endpoint,
-		Infohash:   string(infohash),
-		Left:       left,
-		NumWant:    int(numWant),
-		PeerID:     string(peerID),
-		Uploaded:   uploaded,
-	}, nil
+	// There was no optional parameters to parse.
+	return announce, nil
 }
 
 // newScrape decodes one announce packet, returning a models.Scrape.