From 89e875bf3228dce886a7a3333b960f1ce885a0ed Mon Sep 17 00:00:00 2001
From: lucus <lixin9311@gmail.com>
Date: Wed, 29 Aug 2018 15:48:51 +0900
Subject: [PATCH] Fix the overlap problem of udp decryption. Now return the
 correct length of data read by ReadFrom.

---
 shadowaead/packet.go   | 8 ++++++--
 shadowstream/packet.go | 2 +-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/shadowaead/packet.go b/shadowaead/packet.go
index d8f20a40..ae5f84d4 100644
--- a/shadowaead/packet.go
+++ b/shadowaead/packet.go
@@ -88,6 +88,10 @@ func (c *packetConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	if err != nil {
 		return n, addr, err
 	}
-	b, err = Unpack(b, b[:n], c)
-	return len(b), addr, err
+	bb, err := Unpack(b[c.Cipher.SaltSize():], b[:n], c)
+	if err != nil {
+		return n, addr, err
+	}
+	copy(b, bb)
+	return len(bb), addr, err
 }
diff --git a/shadowstream/packet.go b/shadowstream/packet.go
index b266f581..0defa110 100644
--- a/shadowstream/packet.go
+++ b/shadowstream/packet.go
@@ -76,5 +76,5 @@ func (c *packetConn) ReadFrom(b []byte) (int, net.Addr, error) {
 		return n, addr, err
 	}
 	copy(b, bb)
-	return len(b), addr, err
+	return len(bb), addr, err
 }