From 9860e75cb4037989304187b4af543dacf5a6e312 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Fri, 19 Feb 2016 01:18:31 +0100
Subject: [PATCH] p2p: avoid calling os.Getenv for every handshake

---
 p2p/rlpx.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index feab20ba8d..9d6cba5b67 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -262,6 +262,8 @@ func (h *encHandshake) staticSharedSecret(prv *ecdsa.PrivateKey) ([]byte, error)
 	return ecies.ImportECDSA(prv).GenerateShared(h.remotePub, sskLen, sskLen)
 }
 
+var configSendEIP = os.Getenv("RLPX_EIP8") != ""
+
 // initiatorEncHandshake negotiates a session token on conn.
 // it should be called on the dialing side of the connection.
 //
@@ -273,7 +275,7 @@ func initiatorEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, remoteID d
 		return s, err
 	}
 	var authPacket []byte
-	if os.Getenv("RLPX_EIP8") != "" {
+	if configSendEIP {
 		authPacket, err = sealEIP8(authMsg, h)
 	} else {
 		authPacket, err = authMsg.sealPlain(h)