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-module(coap_unparse).
-export([build_request/2,
build_response/3,
build_text_response/4,
method_name/1]).
-include("coaperl.hrl").
coap_scheme_defaults() ->
[{coap, 5683},
{coaps, 5684},
{'coap+tcp', 5683},
{'coaps+tcp', 443}
].
% RFC7252, Section 3
types() ->
[{confirmable, 0},
{nonconfirmable, 1},
{acknowledgement, 2},
{reset, 3}].
type_code(Type) ->
proplists:get_value(Type, types()).
% RFC7252, Section 3
%% code() ->
%% [{request, 0},
%% {success, 2},
%% {clienterror, 4},
%% {servererror, 5}].
% RFC7252, Section 12.1.1
methods() ->
[{get, 1},
{post, 2},
{put, 3},
{delete, 4}
].
method_code(Method) ->
proplists:get_value(Method, methods()).
method_name(Number) ->
{Method, Number} = lists:keyfind(Number, 2, methods()),
Method.
-spec uri_to_options(string()) -> [{string(), integer(), list()}].
% convert an URI to the corresponding COAP Options
uri_to_options(Uri) ->
{ok, {_, _, Host, Port, Path, _}} = http_uri:parse(Uri,
[{scheme_defaults, coap_scheme_defaults()},
{ipv6_host_with_brackets, true}]),
% Remove brackets from addr if present
Host2 = case Host of
[$[|T] -> [X || X <- T, X =/= $]];
_ -> Host
end,
{Host2, Port, path_to_options(Path)}.
% convert an URI path to the corresponding COAP Options
path_to_options([$/|Path]) ->
lists:reverse(path_to_options(string:tokens(Path, "/"), [])).
path_to_options([], Options) ->
Options;
path_to_options([H|T], Options) ->
path_to_options(T, [{?COAP_OPTION_URI_PATH, H}|Options]).
-spec content_format_to_options(string()) -> [{integer(), integer()}].
% @doc: convert a content format into a number (12.3)
content_format_to_options(ContentFormat) ->
FormatNum = corerl:content_format_number(ContentFormat),
[{?COAP_OPTION_CONTENT_FORMAT, FormatNum}].
-spec num_bytes(integer()) -> integer().
num_bytes(Val) when is_integer(Val), Val =< 16#ff ->
1;
num_bytes(Val) when is_integer(Val), Val =< 16#ffff ->
2;
num_bytes(Val) when is_integer(Val), Val =< 16#ffffff ->
3.
-spec option_length(integer() | binary() | list()) -> integer().
option_length(Val) when is_integer(Val) ->
num_bytes(Val);
option_length(Val) when is_binary(Val) ->
byte_size(Val);
option_length(Val) when is_list(Val) ->
string:len(Val).
-spec option_format_int(integer()) -> {integer(), integer(), integer()}.
option_format_int(Val) ->
case Val of
X when X < 13 ->
{X, 0, 0};
X when 13 =< X, X < 269 ->
{13, X-13, 8};
X when X >= 14 ->
{14, X-269, 16}
end.
-spec options_to_bin(list()) -> iolist().
options_to_bin(Options) ->
% FIXME: sort options by number here
options_to_bin(Options, 0, []).
options_to_bin([], _, Acc) ->
lists:reverse(Acc);
options_to_bin([{Num, Val}|T], OldNum, Acc) when is_integer(Num)->
Diff = Num - OldNum,
if Diff < 0 -> erlang:error(badarith);
true -> true
end,
Len = option_length(Val),
{Delta, ExtDelta, ExtDeltaBits} = option_format_int(Diff),
{Length, ExtLength, ExtLengthBits} = option_format_int(Len),
NewBin = [[<<Delta:4, Length:4,
ExtDelta:ExtDeltaBits,
ExtLength:ExtLengthBits>>,
Val] | Acc],
options_to_bin(T, Num, NewBin).
build_request([{url, Url}, {method, Method}], Msgid, Options) ->
{Host, Port, UriOptions} = uri_to_options(Url),
BinOptions = options_to_bin(UriOptions ++ Options),
MethodNumber = method_code(Method),
Type = type_code(confirmable),
{Host, Port, [<<1:2, Type:2, 0:4, 0:3, MethodNumber:5, Msgid:16>>, BinOptions]}.
build_request(Url, Msgid) ->
build_request([{url, Url}, {method, get}], Msgid, []).
build_response(Class, Detail, Msgid) ->
Type = type_code(confirmable),
[<<1:2, Type:2, 0:4, Class:3, Detail:5, Msgid:16>>].
build_text_response(Class, Detail, Msgid, Payload) ->
Options = content_format_to_options("text/plain"),
BinOptions = options_to_bin(Options),
Type = type_code(confirmable),
[<<1:2, Type:2, 0:4, Class:3, Detail:5, Msgid:16>>, BinOptions, ?COAP_PAYLOAD_MARKER, Payload].
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
option_delta_test() ->
% Check if we encode the option delta correctly
?assertEqual(options_to_bin([{11, "foo"}]),
[[<<11:4, 3:4>>, "foo"]]),
?assertEqual(options_to_bin([{15, "foo"}]),
[[<<13:4, 3:4, 2:8>>, "foo"]]),
?assertEqual(options_to_bin([{275, "foo"}]),
[[<<14:4, 3:4, 6:16>>, "foo"]]).
option_length_test() ->
% Check if we encode the option value length correctly
?assertEqual(options_to_bin([{11, "12345678901234"}]),
[[<<11:4, 13:4, 1:8>>, "12345678901234"]]),
% integer represented in one byte
?assertEqual(options_to_bin([{11, 24}]),
[[<<11:4, 1:4>>, 24]]),
% integer represented in two bytes
?assertEqual(options_to_bin([{11, 324}]),
[[<<11:4, 2:4>>, 324]]),
% integer represented in three bytes
?assertEqual(options_to_bin([{11, 70024}]),
[[<<11:4, 3:4>>, 70024]]).
path_to_options_test() ->
Path = "/.well-known/core",
Ret = path_to_options(Path),
?assertEqual(Ret, [{11,".well-known"},{11,"core"}]).
uri_to_options_test() ->
Uri = "coap://[::1]/.well-known/core",
Ret = uri_to_options(Uri),
?assertEqual(Ret, {"::1", 5683, [{11,".well-known"},{11,"core"}]}).
-endif.
|
