From 528dd1ec72fee1dd63c734fe92d1b972b5735b8f Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Fri, 31 Jan 2020 13:24:48 -0800
Subject: Extract multicast IP to Ethernet address mapping

Test: header.TestEthernetAddressFromMulticastIPAddress
PiperOrigin-RevId: 292604649
---
 pkg/tcpip/network/arp/arp.go | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

(limited to 'pkg/tcpip/network/arp/arp.go')

diff --git a/pkg/tcpip/network/arp/arp.go b/pkg/tcpip/network/arp/arp.go
index 1ceaebfbd..4da13c5df 100644
--- a/pkg/tcpip/network/arp/arp.go
+++ b/pkg/tcpip/network/arp/arp.go
@@ -178,24 +178,9 @@ func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bo
 		return broadcastMAC, true
 	}
 	if header.IsV4MulticastAddress(addr) {
-		// RFC 1112 Host Extensions for IP Multicasting
-		//
-		// 6.4. Extensions to an Ethernet Local Network Module:
-		//
-		// An IP host group address is mapped to an Ethernet multicast
-		// address by placing the low-order 23-bits of the IP address
-		// into the low-order 23 bits of the Ethernet multicast address
-		// 01-00-5E-00-00-00 (hex).
-		return tcpip.LinkAddress([]byte{
-			0x01,
-			0x00,
-			0x5e,
-			addr[header.IPv4AddressSize-3] & 0x7f,
-			addr[header.IPv4AddressSize-2],
-			addr[header.IPv4AddressSize-1],
-		}), true
+		return header.EthernetAddressFromMulticastIPv4Address(addr), true
 	}
-	return "", false
+	return tcpip.LinkAddress([]byte(nil)), false
 }
 
 // SetOption implements NetworkProtocol.
-- 
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