Fix parser contract errors

lib/exmbus/crypto.ex

@@ -26,12 +26,12 @@ defmodule Exmbus.Crypto do
           iv :: iodata(),
           data :: iodata(),
           flag_or_options :: crypto_opts() | boolean()
-        ) :: {:ok, binary} | {:error, crypto_error()}
+        ) :: {:ok, binary} | {:error, {:crypto_error, crypto_error()}}
   def crypto_one_time(cipher, key, iv, data, flag_or_options) do
     try do
       {:ok, :crypto.crypto_one_time(cipher, key, iv, data, flag_or_options)}
     catch
-      :error, {_tag, _c_file_info, _description} = e -> {:error, e}
+      :error, {_tag, _c_file_info, _description} = e -> {:error, {:crypto_error, e}}
     end
   end
 
@@ -43,7 +43,7 @@ defmodule Exmbus.Crypto do
           key :: iodata(),
           data :: iodata(),
           flag_or_options :: crypto_opts() | boolean()
-        ) :: {:ok, binary} | {:error, crypto_error()}
+        ) :: {:ok, binary} | {:error, {:crypto_error, crypto_error()}}
   def crypto_one_time(cipher, key, data, flag_or_options) do
     try do
       {:ok, :crypto.crypto_one_time(cipher, key, data, flag_or_options)}

lib/exmbus/parser/afl.ex

@@ -82,9 +82,23 @@ defmodule Exmbus.Parser.Afl do
   # see table in module doc
   # we can parse up to the MAC
   def parse(%{bin: <<0x90, afll::8, afl_bytes::binary-size(afll), rest::binary>>} = ctx) do
-    <<fcl_bytes::binary-size(2), bytes::binary>> = afl_bytes
-    {:ok, fcl} = FragmentationControlField.decode(fcl_bytes)
+    with <<fcl_bytes::binary-size(2), bytes::binary>> <- afl_bytes,
+         {:ok, fcl} <- FragmentationControlField.decode(fcl_bytes) do
+      parse_fields(ctx, fcl, bytes, rest)
+    else
+      _ -> {:halt, Context.add_error(ctx, {:invalid_afl, :truncated})}
+    end
+  end
 
+  def parse(%{bin: <<0x90, _rest::binary>>} = ctx) do
+    {:halt, Context.add_error(ctx, {:invalid_afl, :truncated})}
+  end
+
+  def parse(%{bin: <<ci, _rest::binary>>} = ctx) do
+    {:halt, Context.add_error(ctx, {:ci_not_afl, ci})}
+  end
+
+  defp parse_fields(ctx, fcl, bytes, rest) do
     # our "accumulator" for the AFL layer
     afl = %__MODULE__{fcl: fcl}
 
@@ -119,10 +133,6 @@ defmodule Exmbus.Parser.Afl do
     end
   end
 
-  def parse(%{bin: <<ci, _rest::binary>>} = ctx) do
-    {:halt, Context.add_error(ctx, {:ci_not_afl, ci})}
-  end
-
   @doc """
   Verifies the MAC of the AFL.
   NOTE: This handler should be attached _after_ the TPL has been parsed,

lib/exmbus/parser/dll/mbus.ex

@@ -30,15 +30,19 @@ defmodule Exmbus.Parser.Dll.Mbus do
     end
   end
 
-  defp _parse(<<c::binary-size(1), a, rest::binary>>, ctx) do
-    {:ok, control} = decode_c_field(c)
-
-    dll = %__MODULE__{
-      control: control,
-      address: a
-    }
+  def parse(ctx), do: {:halt, Context.add_error(ctx, {:invalid_dll, :mbus})}
 
-    {:next, %{ctx | dll: dll, bin: rest}}
+  defp _parse(<<c::binary-size(1), a, rest::binary>>, ctx) do
+    with {:ok, control} <- decode_c_field(c) do
+      dll = %__MODULE__{
+        control: control,
+        address: a
+      }
+
+      {:next, %{ctx | dll: dll, bin: rest}}
+    else
+      {:error, reason} -> {:halt, Context.add_error(ctx, reason)}
+    end
   end
 
   def unparse(%{dll: nil} = ctx) do
@@ -69,24 +73,38 @@ defmodule Exmbus.Parser.Dll.Mbus do
   def direction(%__MODULE__{control: :rsp_ud}), do: {:ok, :from_meter}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, _fcv::1, 0x0::4>>),
-    do: raise("SND-NKE not implemented")
+    do: {:error, {:not_implemented, :snd_nke}}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, _fcv::1, 0x3::4>>),
-    do: raise("SND-UD/SND-UD2 not implemented")
+    do: {:error, {:not_implemented, :snd_ud}}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x4::4>>), do: {:ok, :snd_nr}
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x5::4>>), do: raise("SND-UD3 not implemented")
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x5::4>>),
+    do: {:error, {:not_implemented, :snd_ud3}}
+
   defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x6::4>>), do: {:ok, :snd_ir}
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x7::4>>), do: raise("ACC-NR not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x8::4>>), do: raise("ACC-DMD not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xA::4>>), do: raise("REQ-UD1 not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xB::4>>), do: raise("REQ-UD2 not implemented")
 
-  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x0::4>>), do: raise("ACK not implemented")
-  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x1::4>>), do: raise("NACK not implemented")
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x7::4>>),
+    do: {:error, {:not_implemented, :acc_nr}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x8::4>>),
+    do: {:error, {:not_implemented, :acc_dmd}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xA::4>>),
+    do: {:error, {:not_implemented, :req_ud1}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xB::4>>),
+    do: {:error, {:not_implemented, :req_ud2}}
+
+  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x0::4>>),
+    do: {:error, {:not_implemented, :ack}}
+
+  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x1::4>>),
+    do: {:error, {:not_implemented, :nack}}
 
   defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x6::4>>),
-    do: raise("CNF-IR not implemented")
+    do: {:error, {:not_implemented, :cnf_ir}}
 
   defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x8::4>>), do: {:ok, :rsp_ud}
 end

lib/exmbus/parser/dll/wmbus.ex

@@ -89,6 +89,8 @@ defmodule Exmbus.Parser.Dll.Wmbus do
     end
   end
 
+  defp do_parse(ctx), do: {:halt, Context.add_error(ctx, {:invalid_dll, :wmbus})}
+
   def unparse(%{dll: nil} = ctx) do
     {:next, ctx}
   end
@@ -137,24 +139,38 @@ defmodule Exmbus.Parser.Dll.Wmbus do
   def direction(%__MODULE__{control: :rsp_ud}), do: {:ok, :from_meter}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, _fcv::1, 0x0::4>>),
-    do: raise("SND-NKE not implemented")
+    do: {:error, {:not_implemented, :snd_nke}}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, _fcv::1, 0x3::4>>),
-    do: raise("SND-UD/SND-UD2 not implemented")
+    do: {:error, {:not_implemented, :snd_ud}}
 
   defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x4::4>>), do: {:ok, :snd_nr}
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x5::4>>), do: raise("SND-UD3 not implemented")
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x5::4>>),
+    do: {:error, {:not_implemented, :snd_ud3}}
+
   defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x6::4>>), do: {:ok, :snd_ir}
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x7::4>>), do: raise("ACC-NR not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x8::4>>), do: raise("ACC-DMD not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xA::4>>), do: raise("REQ-UD1 not implemented")
-  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xB::4>>), do: raise("REQ-UD2 not implemented")
 
-  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x0::4>>), do: raise("ACK not implemented")
-  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x1::4>>), do: raise("NACK not implemented")
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x7::4>>),
+    do: {:error, {:not_implemented, :acc_nr}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 0::1, 0x8::4>>),
+    do: {:error, {:not_implemented, :acc_dmd}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xA::4>>),
+    do: {:error, {:not_implemented, :req_ud1}}
+
+  defp decode_c_field(<<0::1, 1::1, _fcb::1, 1::1, 0xB::4>>),
+    do: {:error, {:not_implemented, :req_ud2}}
+
+  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x0::4>>),
+    do: {:error, {:not_implemented, :ack}}
+
+  defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x1::4>>),
+    do: {:error, {:not_implemented, :nack}}
 
   defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x6::4>>),
-    do: raise("CNF-IR not implemented")
+    do: {:error, {:not_implemented, :cnf_ir}}
 
   defp decode_c_field(<<0::1, 0::1, _acd::1, _dfc::1, 0x8::4>>), do: {:ok, :rsp_ud}
 

lib/exmbus/parser/ell.ex

@@ -38,14 +38,16 @@ defmodule Exmbus.Parser.Ell do
   # > Table 44 below, shows the complete extension block in this case.
   # Fields: CC, ACC
   def parse(%{bin: <<0x8C, cc::binary-size(1), acc, rest::binary>>} = ctx) do
-    {:ok, control} = CommunicationControl.decode(cc)
+    with {:ok, control} <- CommunicationControl.decode(cc) do
+      ell = %Unencrypted{
+        communication_control: control,
+        access_no: acc
+      }
 
-    ell = %Unencrypted{
-      communication_control: control,
-      access_no: acc
-    }
-
-    {:next, %{ctx | ell: ell, bin: rest}}
+      {:next, %{ctx | ell: ell, bin: rest}}
+    else
+      {:error, reason} -> {:halt, Context.add_error(ctx, {:ell_parse_error, reason, ci: 0x8C})}
+    end
   end
 
   # > This value of the CI-field is used if data encryption at the link layer is used in the frame.
@@ -58,16 +60,18 @@ defmodule Exmbus.Parser.Ell do
               rest::binary>>
         } = ctx
       ) do
-    {:ok, control} = CommunicationControl.decode(cc)
-    {:ok, session_number} = SessionNumber.decode(sn)
-
-    ell = %Encrypted{
-      communication_control: control,
-      access_no: acc,
-      session_number: session_number
-    }
-
-    {:next, %{ctx | ell: ell, bin: <<payload_crc::size(16), rest::binary>>}}
+    with {:ok, control} <- CommunicationControl.decode(cc),
+         {:ok, session_number} <- SessionNumber.decode(sn) do
+      ell = %Encrypted{
+        communication_control: control,
+        access_no: acc,
+        session_number: session_number
+      }
+
+      {:next, %{ctx | ell: ell, bin: <<payload_crc::size(16), rest::binary>>}}
+    else
+      {:error, reason} -> {:halt, Context.add_error(ctx, {:ell_parse_error, reason, ci: 0x8D})}
+    end
   end
 
   # > This value of the CI-field is used if data encryption at the link layer is not used in the frame.
@@ -87,20 +91,26 @@ defmodule Exmbus.Parser.Ell do
   # > This extended link layer specifies the receiver address.
   # > Table 47 below shows the complete extension block in this case.
   # Fields: CC, ACC, M2, A2, SN, PayloadCRC
-  def parse(%{
-        bin:
-          <<0x8F, _cc::binary-size(1), _acc, _m2::binary-size(2), _a2::binary-size(6),
-            _sn::binary-size(4), _payload_crc::binary-size(2), _rest::binary>>
-      }) do
-    raise "TODO: ELL IV"
+  def parse(
+        %{
+          bin:
+            <<0x8F, _cc::binary-size(1), _acc, _m2::binary-size(2), _a2::binary-size(6),
+              _sn::binary-size(4), _payload_crc::binary-size(2), _rest::binary>>
+        } = ctx
+      ) do
+    {:halt, Context.add_error(ctx, {:not_implemented, :ell_iv})}
   end
 
   # > The variable Extended Link Layer allows to select optional ELL fields separately.
   # > The shadowed rows of Table 48 shall always be present.
   # > The other fields are optional and can be selected in case they are needed.
   # > The table defines the ordering of the fields.
-  def parse(%{bin: <<0x86, _rest::binary>>}) do
-    raise "TODO: ELL V"
+  def parse(%{bin: <<0x86, _rest::binary>>} = ctx) do
+    {:halt, Context.add_error(ctx, {:not_implemented, :ell_v})}
+  end
+
+  def parse(%{bin: <<ci, _rest::binary>>} = ctx) when ci in [0x8C, 0x8D, 0x8E, 0x8F] do
+    {:halt, Context.add_error(ctx, {:ell_parse_error, :truncated, ci: ci})}
   end
 
   def parse(%{bin: <<ci, _rest::binary>>} = ctx) do

lib/exmbus/parser/ell/session_number.ex

@@ -23,7 +23,7 @@ defmodule Exmbus.Parser.Ell.SessionNumber do
           :aes_128_ctr
 
         enc ->
-          raise "ELL session number encryption mode #{enc} is reserved for future use, see 13.2.11 of EN 13757-4:2019"
+          throw({:error, {:reserved_ell_session_encryption_mode, enc}})
       end
 
     {:ok,
@@ -35,6 +35,8 @@ defmodule Exmbus.Parser.Ell.SessionNumber do
        # inter-minute session
        session: session
      }}
+  catch
+    {:error, _} = e -> e
   end
 
   def encode(%__MODULE__{encryption: mode, minutes: m, session: s}) do