diff options
| -rw-r--r-- | dhcpv6/iputils.go | 51 | ||||
| -rw-r--r-- | dhcpv6/iputils_test.go | 29 |
2 files changed, 80 insertions, 0 deletions
diff --git a/dhcpv6/iputils.go b/dhcpv6/iputils.go index 2b9788c..3ad157e 100644 --- a/dhcpv6/iputils.go +++ b/dhcpv6/iputils.go @@ -42,3 +42,54 @@ func GetGlobalAddr(ifname string) (net.IP, error) { return ip.To4() == nil && ip.IsGlobalUnicast() }) } + +// GetMacAddressFromEUI64 will return a valid MAC address ONLY if it's a EUI-48 +func GetMacAddressFromEUI64(ip net.IP) (net.HardwareAddr, error) { + if ip.To16() == nil { + return nil, fmt.Errorf("IP address shorter than 16 bytes") + } + + if isEUI48 := ip[11] == 0xff && ip[12] == 0xfe; !isEUI48 { + return nil, fmt.Errorf("IP address is not an EUI48 address") + } + + mac := make(net.HardwareAddr, 6) + copy(mac[0:3], ip[8:11]) + copy(mac[3:6], ip[13:16]) + mac[0] ^= 0x02 + + return mac, nil +} + +// ExtractMAC looks into the inner most PeerAddr field in the RelayInfo header +// which contains the EUI-64 address of the client making the request, populated +// by the dhcp relay, it is possible to extract the mac address from that IP. +// If that fails, it looks for the MAC addressed embededded in the DUID. +// Note that this only works with type DuidLL and DuidLLT. +// If a mac address cannot be found an error will be returned. +func ExtractMAC(packet DHCPv6) (net.HardwareAddr, error) { + msg := packet + if packet.IsRelay() { + inner, err := DecapsulateRelayIndex(packet, -1) + if err != nil { + return nil, err + } + ip := inner.(*DHCPv6Relay).PeerAddr() + if mac, err := GetMacAddressFromEUI64(ip); err == nil { + return mac, nil + } + msg, err = msg.(*DHCPv6Relay).GetInnerMessage() + if err != nil { + return nil, err + } + } + optclientid := msg.GetOneOption(OptionClientID) + if optclientid == nil { + return nil, fmt.Errorf("client ID not found in packet") + } + duid := optclientid.(*OptClientId).Cid + if duid.LinkLayerAddr == nil { + return nil, fmt.Errorf("failed to extract MAC") + } + return duid.LinkLayerAddr, nil +} diff --git a/dhcpv6/iputils_test.go b/dhcpv6/iputils_test.go index 765792e..1da249d 100644 --- a/dhcpv6/iputils_test.go +++ b/dhcpv6/iputils_test.go @@ -7,6 +7,7 @@ import ( "testing" "github.com/stretchr/testify/mock" + "github.com/stretchr/testify/require" "github.com/stretchr/testify/suite" ) @@ -101,3 +102,31 @@ func (s *MatchingAddressTestSuite) TestGetGlobalAddr() { func TestMatchingAddressTestSuite(t *testing.T) { suite.Run(t, new(MatchingAddressTestSuite)) } + +func Test_ExtractMAC(t *testing.T) { + //SOLICIT message wrapped in Relay-Forw + var relayForwBytesDuidUUID = []byte{ + 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x26, 0x8a, 0x07, 0xff, 0xfe, 0x56, + 0xdc, 0xa4, 0x00, 0x12, 0x00, 0x06, 0x24, 0x8a, + 0x07, 0x56, 0xdc, 0xa4, 0x00, 0x09, 0x00, 0x5a, + 0x06, 0x7d, 0x9b, 0xca, 0x00, 0x01, 0x00, 0x12, + 0x00, 0x04, 0xb7, 0xfd, 0x0a, 0x8c, 0x1b, 0x14, + 0x10, 0xaa, 0xeb, 0x0a, 0x5b, 0x3f, 0xe8, 0x9d, + 0x0f, 0x56, 0x00, 0x06, 0x00, 0x0a, 0x00, 0x17, + 0x00, 0x18, 0x00, 0x17, 0x00, 0x18, 0x00, 0x01, + 0x00, 0x08, 0x00, 0x02, 0xff, 0xff, 0x00, 0x03, + 0x00, 0x28, 0x07, 0x56, 0xdc, 0xa4, 0x00, 0x00, + 0x0e, 0x10, 0x00, 0x00, 0x15, 0x18, 0x00, 0x05, + 0x00, 0x18, 0x26, 0x20, 0x01, 0x0d, 0xc0, 0x82, + 0x90, 0x63, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0xaf, 0xa0, 0x00, 0x00, 0x1c, 0x20, 0x00, 0x00, + 0x1d, 0x4c} + packet, err := FromBytes(relayForwBytesDuidUUID) + require.NoError(t, err) + mac, err := ExtractMAC(packet) + require.NoError(t, err) + require.Equal(t, mac.String(), "24:8a:07:56:dc:a4") +} |