diff options
Diffstat (limited to 'pkg/tcpip/header/ipv6.go')
-rw-r--r-- | pkg/tcpip/header/ipv6.go | 95 |
1 files changed, 80 insertions, 15 deletions
diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go index 093850e25..fc671e439 100644 --- a/pkg/tcpip/header/ipv6.go +++ b/pkg/tcpip/header/ipv6.go @@ -76,15 +76,37 @@ const ( // IPv6Version is the version of the ipv6 protocol. IPv6Version = 6 + // IPv6AllNodesMulticastAddress is a link-local multicast group that + // all IPv6 nodes MUST join, as per RFC 4291, section 2.8. Packets + // destined to this address will reach all nodes on a link. + // + // The address is ff02::1. + IPv6AllNodesMulticastAddress tcpip.Address = "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01" + // IPv6MinimumMTU is the minimum MTU required by IPv6, per RFC 2460, // section 5. IPv6MinimumMTU = 1280 - // IPv6Any is the non-routable IPv6 "any" meta address. + // IPv6Any is the non-routable IPv6 "any" meta address. It is also + // known as the unspecified address. IPv6Any tcpip.Address = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" + + // IIDSize is the size of an interface identifier (IID), in bytes, as + // defined by RFC 4291 section 2.5.1. + IIDSize = 8 + + // IIDOffsetInIPv6Address is the offset, in bytes, from the start + // of an IPv6 address to the beginning of the interface identifier + // (IID) for auto-generated addresses. That is, all bytes before + // the IIDOffsetInIPv6Address-th byte are the prefix bytes, and all + // bytes including and after the IIDOffsetInIPv6Address-th byte are + // for the IID. + IIDOffsetInIPv6Address = 8 ) -// IPv6EmptySubnet is the empty IPv6 subnet. +// IPv6EmptySubnet is the empty IPv6 subnet. It may also be known as the +// catch-all or wildcard subnet. That is, all IPv6 addresses are considered to +// be contained within this subnet. var IPv6EmptySubnet = func() tcpip.Subnet { subnet, err := tcpip.NewSubnet(IPv6Any, tcpip.AddressMask(IPv6Any)) if err != nil { @@ -93,6 +115,15 @@ var IPv6EmptySubnet = func() tcpip.Subnet { return subnet }() +// IPv6LinkLocalPrefix is the prefix for IPv6 link-local addresses, as defined +// by RFC 4291 section 2.5.6. +// +// The prefix is fe80::/64 +var IPv6LinkLocalPrefix = tcpip.AddressWithPrefix{ + Address: "\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", + PrefixLen: 64, +} + // PayloadLength returns the value of the "payload length" field of the ipv6 // header. func (b IPv6) PayloadLength() uint16 { @@ -221,6 +252,24 @@ func IsV6MulticastAddress(addr tcpip.Address) bool { return addr[0] == 0xff } +// IsV6UnicastAddress determines if the provided address is a valid IPv6 +// unicast (and specified) address. That is, IsV6UnicastAddress returns +// true if addr contains IPv6AddressSize bytes, is not the unspecified +// address and is not a multicast address. +func IsV6UnicastAddress(addr tcpip.Address) bool { + if len(addr) != IPv6AddressSize { + return false + } + + // Must not be unspecified + if addr == IPv6Any { + return false + } + + // Return if not a multicast. + return addr[0] != 0xff +} + // SolicitedNodeAddr computes the solicited-node multicast address. This is // used for NDP. Described in RFC 4291. The argument must be a full-length IPv6 // address. @@ -229,27 +278,43 @@ func SolicitedNodeAddr(addr tcpip.Address) tcpip.Address { return solicitedNodeMulticastPrefix + addr[len(addr)-3:] } +// EthernetAdddressToModifiedEUI64IntoBuf populates buf with a modified EUI-64 +// from a 48-bit Ethernet/MAC address, as per RFC 4291 section 2.5.1. +// +// buf MUST be at least 8 bytes. +func EthernetAdddressToModifiedEUI64IntoBuf(linkAddr tcpip.LinkAddress, buf []byte) { + buf[0] = linkAddr[0] ^ 2 + buf[1] = linkAddr[1] + buf[2] = linkAddr[2] + buf[3] = 0xFF + buf[4] = 0xFE + buf[5] = linkAddr[3] + buf[6] = linkAddr[4] + buf[7] = linkAddr[5] +} + +// EthernetAddressToModifiedEUI64 computes a modified EUI-64 from a 48-bit +// Ethernet/MAC address, as per RFC 4291 section 2.5.1. +func EthernetAddressToModifiedEUI64(linkAddr tcpip.LinkAddress) [IIDSize]byte { + var buf [IIDSize]byte + EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, buf[:]) + return buf +} + // LinkLocalAddr computes the default IPv6 link-local address from a link-layer // (MAC) address. func LinkLocalAddr(linkAddr tcpip.LinkAddress) tcpip.Address { - // Convert a 48-bit MAC to an EUI-64 and then prepend the link-local - // header, FE80::. + // Convert a 48-bit MAC to a modified EUI-64 and then prepend the + // link-local header, FE80::. // // The conversion is very nearly: // aa:bb:cc:dd:ee:ff => FE80::Aabb:ccFF:FEdd:eeff // Note the capital A. The conversion aa->Aa involves a bit flip. - lladdrb := [16]byte{ - 0: 0xFE, - 1: 0x80, - 8: linkAddr[0] ^ 2, - 9: linkAddr[1], - 10: linkAddr[2], - 11: 0xFF, - 12: 0xFE, - 13: linkAddr[3], - 14: linkAddr[4], - 15: linkAddr[5], + lladdrb := [IPv6AddressSize]byte{ + 0: 0xFE, + 1: 0x80, } + EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, lladdrb[IIDOffsetInIPv6Address:]) return tcpip.Address(lladdrb[:]) } |