@spec add([ie()], binary()) :: {:ok, binary()} | {:error, any()}

Encodes IEs and prepends message with the encoded value.

The result is one of the following:

• {:ok, message} where message is the original message prefixed with UDH;
• {:error, reason} in case of errors.

Example

iex> ies = [{0x05, <<0x06, 0x2d, 0x00, 0x00>>}, {0x00, <<0x01, 0x02, 0x01>>}]
iex> SMPPEX.Pdu.UDH.add(ies, "message")
{:ok, <<0x0B, 0x05, 0x04, 0x06, 0x2d, 0x00, 0x00, 0x00, 0x03, 0x01, 0x02, 0x01, "message">>}

iex> ies = [{0, 123}]
iex> SMPPEX.Pdu.UDH.add(ies, "message")
{:error, "Invalid UDH IE data"}

iex> ies = [{345, "ie"}]
iex> SMPPEX.Pdu.UDH.add(ies, "message")
{:error, "Invalid UDH IE id"}

iex> ies = [{-1, "ie"}]
iex> SMPPEX.Pdu.UDH.add(ies, "message")
{:error, "Invalid UDH IE id"}

iex> ies = [{0, <<1 :: integer-size(2040)>>}]
iex> SMPPEX.Pdu.UDH.add(ies, "message")
{:error, "UDH is too long"}

@spec extract(message :: binary()) :: {:error, term()} | {:ok, [ie()], binary()}

Extracts list of IEs from UDH.

Returns one of the following

• {:ok, ies, message} where ies is a list of IE tuples {id, value} and message is the original message without UDH;
• {:error, reason} in case of errors.

Example

iex> data = <<5, 0, 3, 197, 3, 3, "message">>
iex> SMPPEX.Pdu.UDH.extract(data)
{:ok, [{0, <<197, 3, 3>>}], "message"}

iex> data = <<0x0B, 0x05, 0x04, 0x06, 0x2d, 0x00, 0x00, 0x00, 0x03, 0x01, 0x02, 0x01, "message">>
iex> SMPPEX.Pdu.UDH.extract(data)
{:ok, [{0x05, <<0x06, 0x2d, 0x00, 0x00>>}, {0x00, <<0x01, 0x02, 0x01>>}], "message"}

iex> data = <<0x10, "short">>
iex> SMPPEX.Pdu.UDH.extract(data)
{:error, "Invalid UDH length"}

iex> data = <<0x06, 0x00, 0x03, 0x01, 0x02, 0x01, "message">>
iex> SMPPEX.Pdu.UDH.extract(data)
{:error, "Invalid UDH data"}

iex> data = <<5, 0, 4, 197, 3, 3, "message">>
iex> SMPPEX.Pdu.UDH.extract(data)
{:error, "Invalid UDH IE length"}

@spec has_udh?(pdu :: SMPPEX.Pdu.t()) :: boolean()

Checks if message in PDU has UDH (by inspecting esm_class field).

Example

iex> pdu = SMPPEX.Pdu.new({1,0,1}, %{esm_class: 0}, %{})
iex> SMPPEX.Pdu.UDH.has_udh?(pdu)
false

iex> pdu = SMPPEX.Pdu.new({1,0,1}, %{esm_class: 0b01000000}, %{})
iex> SMPPEX.Pdu.UDH.has_udh?(pdu)
true