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[sctp] encode/decode #26

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Jul 3, 2024
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[sctp] encode/decode #26

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ba888d4
[sctp] encode/decode
sebastiw Jun 24, 2024
0a126f4
otc-api
sebastiw Jun 24, 2024
7ec179a
readme
sebastiw Jun 24, 2024
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12 changes: 10 additions & 2 deletions README.org
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Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,12 @@

* Usage

otc can be called with both decode/2, decode/3, as well as decapsulate/2, decapsulate/3 functions.
The differens is that decapsulate will crash on errors while decode returns an error-tuple.
otc can be called with both `decode/2`, `decode/3`, as well as
`decapsulate/2`, `decapsulate/3` functions. The differens is that
decapsulate will crash on errors while decode returns an
error-tuple.

`decode/1` and `decapsulate/1` assumes SCTP packets.

In successful cases `decode` will return an ok-tuple containing
either (only) a list of headers if the binary was fully decoded, or
Expand All @@ -42,6 +46,9 @@

6> otc:decapsulate(m2pa, LinkBinary).
[#{protocol := m2pa, ..}]

7> otc:decode(SctpBinary).
{ok, [#{protocol := sctp, ..}]}
#+END_SRC

For encoding there is only one function encode/1, but it can take
Expand Down Expand Up @@ -79,6 +86,7 @@

| Name | Spec | Decode | Encode | Production Tested (Decode/Encode) | Notes |
|---------+-------------------------------+--------+--------+-----------------------------------+-------------------------------------------------------|
| SCTP | IETF RFC 2960 October 2000 | X | X | | |
| M3UA | IETF RFC 4666 September 2006 | X | X | DE | |
| M2PA | IETF RFC 4165 September 2005 | X | X | DE | |
| MTP3 | ITU-T Q.704 (07/96) July 1996 | X | X | DE | |
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37 changes: 21 additions & 16 deletions src/otc.erl
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Expand Up @@ -3,7 +3,7 @@

%% Supported protocol
-export([sctp_ppi/1,
%% sctp/1,
sctp/1,
m2pa/1,
mtp3/1,
m3ua/1,
Expand All @@ -23,10 +23,10 @@
]).

%% General functions
-export([%% decapsulate/1,
-export([decapsulate/1,
decapsulate/2,
decapsulate/3,
%% decode/1,
decode/1,
decode/2,
decode/3,
encapsulate/1,
Expand All @@ -37,10 +37,12 @@

%% Supported protocols ---------------------------------------------------------

-type protocol() :: sctp_ppi | m3ua | m2pa | mtp3 | sccp | sccp_mgmt | tcap | map | nas_eps | nas_eps_emm | nas_eps_esm | gtpv1c | gtpv2c | sgsap.
-type protocol() :: sctp_ppi | sctp | m3ua | m2pa | mtp3 | sccp | sccp_mgmt | tcap | map
| nas_eps | nas_eps_emm | nas_eps_esm
| gtpv1c | gtpv2c | sgsap.

next({sctp_ppi, V}) -> otc_sctp_ppi:next(V);
%% next({sctp, V}) -> otc_sctp:next(V);
next({sctp, V}) -> otc_sctp:next(V);
next({m2pa, V}) -> otc_m2pa:next(V);
next({m3ua, V}) -> otc_m3ua:next(V);
next({mtp3, V}) -> otc_mtp3:next(V);
Expand All @@ -59,7 +61,7 @@ next({gtpv2c, V}) -> otc_gtpv2c:next(V);
next({sgsap, V}) -> otc_sgsap:next(V).

sctp_ppi(PPI) -> otc_sctp_ppi:codec(PPI).
%% sctp(D) -> otc_sctp:codec(D).
sctp(D) -> otc_sctp:codec(D).
m2pa(D) -> otc_m2pa:codec(D).
mtp3(D) -> otc_mtp3:codec(D).
m3ua(D) -> otc_m3ua:codec(D).
Expand All @@ -86,19 +88,21 @@ sgsap(D) -> otc_sgsap:codec(D).
-type packet() :: headers() | Decoded :: {headers(), data()} | Decapsulated :: [header() | binary()].
-type payload() :: header() | headers() | {header() | headers(), data()} | {protocol(), header() | {header(), data()}} | data().

-spec otc:decapsulate(data()) -> packet().
-spec otc:decapsulate(protocol(), data()) -> packet().
-spec otc:decapsulate(protocol(), data(), options()) -> packet().
%% decapsulate/1,2 works on valid packets. If the packet is malformed
%% or unsupported, decapsulate/1 will crash.
%% decapsulate/1,2,3 works on valid packets. If the packet is malformed
%% or unsupported, decapsulate/1,2,3 will crash.
decapsulate(Data) when is_binary(Data) ->
decapsulate(sctp, Data).

decapsulate(Proto, Data) ->
decapsulate(Proto, Data, #{}).

decapsulate(PPI, Data, Opts) when is_integer(PPI) ->
decapsulate_next(sctp_ppi(PPI), Data, [], Opts);
decapsulate(Proto, Data, Opts) when is_atom(Proto) ->
decapsulate_next(Proto, Data, [], Opts).
%% decapsulate(Data) when is_binary(Data) ->
%% decapsulate_next({sctp, Data}, []).

decapsulate_next('$stop', Data, Headers, _Opts) ->
lists:reverse([Data|Headers]);
Expand All @@ -112,19 +116,20 @@ decapsulate_next(Proto, Data, Headers, Opts) ->
lists:reverse([Header#{protocol => Proto}|Headers])
end.

%% -spec otc:decode(data()) ->
%% {ok, packet()} |
%% {error, SoFar :: headers(), {FailedProto :: protocol(), data()}}.
-spec otc:decode(data()) ->
{ok, packet()} |
{error, SoFar :: headers(), {FailedProto :: protocol(), data()}}.
-spec otc:decode(protocol(), data()) ->
{ok, packet()} |
{error, SoFar :: headers(), {FailedProto :: protocol(), data()}}.
-spec otc:decode(protocol(), data(), options()) ->
{ok, packet()} |
{error, SoFar :: headers(), {FailedProto :: protocol(), data()}}.
%% Similar to decapsulate/1 but, on error, returns any part of the
%% Similar to decapsulate/1,2,3 but, on error, returns any part of the
%% packet that has been successfully converted to Erlang term format.
%% decode(Data) when is_binary(Data) ->
%% decode(sctp, Data).
decode(Data) when is_binary(Data) ->
decode(sctp, Data).

decode(P, Data) ->
decode(P, Data, #{}).

Expand Down
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