diff options
Diffstat (limited to 'pkg/tcpip/header/eth.go')
| -rw-r--r-- | pkg/tcpip/header/eth.go | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/pkg/tcpip/header/eth.go b/pkg/tcpip/header/eth.go index f5d2c127f..eaface8cb 100644 --- a/pkg/tcpip/header/eth.go +++ b/pkg/tcpip/header/eth.go @@ -53,6 +53,10 @@ const ( // (all bits set to 0). unspecifiedEthernetAddress = tcpip.LinkAddress("\x00\x00\x00\x00\x00\x00") + // EthernetBroadcastAddress is an ethernet address that addresses every node + // on a local link. + EthernetBroadcastAddress = tcpip.LinkAddress("\xff\xff\xff\xff\xff\xff") + // unicastMulticastFlagMask is the mask of the least significant bit in // the first octet (in network byte order) of an ethernet address that // determines whether the ethernet address is a unicast or multicast. If @@ -134,3 +138,44 @@ 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[:]) +} |