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Diffstat (limited to 'src/coap_unparse.erl')
| -rw-r--r-- | src/coap_unparse.erl | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/src/coap_unparse.erl b/src/coap_unparse.erl new file mode 100644 index 0000000..aaca450 --- /dev/null +++ b/src/coap_unparse.erl @@ -0,0 +1,195 @@ +-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. |