diff options
| -rw-r--r-- | pkg/tcpip/header/eth.go | 41 | ||||
| -rw-r--r-- | pkg/tcpip/header/eth_test.go | 34 | ||||
| -rw-r--r-- | pkg/tcpip/network/arp/arp.go | 19 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv6/icmp.go | 20 |
4 files changed, 79 insertions, 35 deletions
diff --git a/pkg/tcpip/header/eth.go b/pkg/tcpip/header/eth.go index f5d2c127f..b1e92d2d7 100644 --- a/pkg/tcpip/header/eth.go +++ b/pkg/tcpip/header/eth.go @@ -134,3 +134,44 @@ func IsValidUnicastEthernetAddress(addr tcpip.LinkAddress) bool { // addr is a valid unicast ethernet address. return true } + +// EthernetAddressFromMulticastIPv4Address returns a multicast Ethernet address +// for a multicast IPv4 address. +// +// addr MUST be a multicast IPv4 address. +func EthernetAddressFromMulticastIPv4Address(addr tcpip.Address) tcpip.LinkAddress { + var linkAddrBytes [EthernetAddressSize]byte + // 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). + linkAddrBytes[0] = 0x1 + linkAddrBytes[2] = 0x5e + linkAddrBytes[3] = addr[1] & 0x7F + copy(linkAddrBytes[4:], addr[IPv4AddressSize-2:]) + return tcpip.LinkAddress(linkAddrBytes[:]) +} + +// EthernetAddressFromMulticastIPv6Address returns a multicast Ethernet address +// for a multicast IPv6 address. +// +// addr MUST be a multicast IPv6 address. +func EthernetAddressFromMulticastIPv6Address(addr tcpip.Address) tcpip.LinkAddress { + // RFC 2464 Transmission of IPv6 Packets over Ethernet Networks + // + // 7. Address Mapping -- Multicast + // + // An IPv6 packet with a multicast destination address DST, + // consisting of the sixteen octets DST[1] through DST[16], is + // transmitted to the Ethernet multicast address whose first + // two octets are the value 3333 hexadecimal and whose last + // four octets are the last four octets of DST. + linkAddrBytes := []byte(addr[IPv6AddressSize-EthernetAddressSize:]) + linkAddrBytes[0] = 0x33 + linkAddrBytes[1] = 0x33 + return tcpip.LinkAddress(linkAddrBytes[:]) +} diff --git a/pkg/tcpip/header/eth_test.go b/pkg/tcpip/header/eth_test.go index 6634c90f5..7a0014ad9 100644 --- a/pkg/tcpip/header/eth_test.go +++ b/pkg/tcpip/header/eth_test.go @@ -66,3 +66,37 @@ func TestIsValidUnicastEthernetAddress(t *testing.T) { }) } } + +func TestEthernetAddressFromMulticastIPv4Address(t *testing.T) { + tests := []struct { + name string + addr tcpip.Address + expectedLinkAddr tcpip.LinkAddress + }{ + { + name: "IPv4 Multicast without 24th bit set", + addr: "\xe0\x7e\xdc\xba", + expectedLinkAddr: "\x01\x00\x5e\x7e\xdc\xba", + }, + { + name: "IPv4 Multicast with 24th bit set", + addr: "\xe0\xfe\xdc\xba", + expectedLinkAddr: "\x01\x00\x5e\x7e\xdc\xba", + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + if got := EthernetAddressFromMulticastIPv4Address(test.addr); got != test.expectedLinkAddr { + t.Fatalf("got EthernetAddressFromMulticastIPv4Address(%s) = %s, want = %s", got, test.expectedLinkAddr) + } + }) + } +} + +func TestEthernetAddressFromMulticastIPv6Address(t *testing.T) { + addr := tcpip.Address("\xff\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x1a") + if got, want := EthernetAddressFromMulticastIPv6Address(addr), tcpip.LinkAddress("\x33\x33\x0d\x0e\x0f\x1a"); got != want { + t.Fatalf("got EthernetAddressFromMulticastIPv6Address(%s) = %s, want = %s", addr, got, want) + } +} 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. diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go index dc20c0fd7..7491cfc41 100644 --- a/pkg/tcpip/network/ipv6/icmp.go +++ b/pkg/tcpip/network/ipv6/icmp.go @@ -441,23 +441,7 @@ func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack. // ResolveStaticAddress implements stack.LinkAddressResolver. func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) { if header.IsV6MulticastAddress(addr) { - // RFC 2464 Transmission of IPv6 Packets over Ethernet Networks - // - // 7. Address Mapping -- Multicast - // - // An IPv6 packet with a multicast destination address DST, - // consisting of the sixteen octets DST[1] through DST[16], is - // transmitted to the Ethernet multicast address whose first - // two octets are the value 3333 hexadecimal and whose last - // four octets are the last four octets of DST. - return tcpip.LinkAddress([]byte{ - 0x33, - 0x33, - addr[header.IPv6AddressSize-4], - addr[header.IPv6AddressSize-3], - addr[header.IPv6AddressSize-2], - addr[header.IPv6AddressSize-1], - }), true + return header.EthernetAddressFromMulticastIPv6Address(addr), true } - return "", false + return tcpip.LinkAddress([]byte(nil)), false } |