Specs

teredo_decode(prefix()) :: map() | nil

Returns a map with the teredo address components of pfx or nil.

Returns nil if pfx is not a teredo address.

A teredo address consists of:

1. the teredo service prefix of 2000:0::/32
2. IPv4 address of the teredo server
3. flags (16 bits) that document type of address and NAT
4. Port (16 bits), the obfuscated "mapped UDP port" at the client
5. IPv4 address (obfucated) of the teredo client.

More details in rfc4380.

Examples

# example from https://en.wikipedia.org/wiki/Teredo_tunneling#IPv6_addressing
iex> teredo_decode("2001:0000:4136:e378:8000:63bf:3fff:fdd2")
%{
  server: "65.54.227.120",
  client: "192.0.2.45",
  port: 40000,
  flags: {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  prefix: "2001:0000:4136:e378:8000:63bf:3fff:fdd2"
}

iex> teredo_decode({0x2001, 0, 0x4136, 0xe378, 0x8000, 0x63bf, 0x3fff, 0xfdd2})
%{
  server: {65, 54, 227, 120},
  client: {192, 0, 2, 45},
  port: 40000,
  flags: {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  prefix: {0x2001, 0x0, 0x4136, 0xe378, 0x8000, 0x63bf, 0x3fff, 0xfdd2}
}

iex> teredo_decode("1.1.1.1")
nil