From 69d25e845f5fca6ee2446dfe5bbbabc22549f062 Mon Sep 17 00:00:00 2001
From: Tom Thorogood <me+github@tomthorogood.co.uk>
Date: Wed, 10 Jan 2018 00:27:26 +1030
Subject: [PATCH] Fixes #613 & #619 (#621)

* Do not reutrn ErrShortRead in readUDP

A read of zero bytes indicates a peer shutdown for TCP sockets -- and
thus returning ErrShortRead is fine in readTCP -- but not for UDP
sockets. For UDP sockets a read of zero bytes literally indicates a
zero-byte datagram, and is a valid return value not indicating an error.

Removing this case will cause readUDP to correctly return a zero-byte
message.

* Return non-temporary error from serveUDP loop

Fixes #613
---
 server.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/server.go b/server.go
index 136a9a1c..ebe46e4d 100644
--- a/server.go
+++ b/server.go
@@ -509,7 +509,10 @@ func (srv *Server) serveUDP(l *net.UDPConn) error {
 		}
 		srv.lock.RUnlock()
 		if err != nil {
-			continue
+			if netErr, ok := err.(net.Error); ok && netErr.Temporary() {
+				continue
+			}
+			return err
 		}
 		go srv.serve(s.RemoteAddr(), handler, m, l, s, nil)
 	}
@@ -626,11 +629,8 @@ func (srv *Server) readUDP(conn *net.UDPConn, timeout time.Duration) ([]byte, *S
 	conn.SetReadDeadline(time.Now().Add(timeout))
 	m := make([]byte, srv.UDPSize)
 	n, s, err := ReadFromSessionUDP(conn, m)
-	if err != nil || n == 0 {
-		if err != nil {
-			return nil, nil, err
-		}
-		return nil, nil, ErrShortRead
+	if err != nil {
+		return nil, nil, err
 	}
 	m = m[:n]
 	return m, s, nil