From 2f40a69c116c778e4dbc5abeff13c3cbf9758ac8 Mon Sep 17 00:00:00 2001
From: Egobrain <xazar.studio@gmail.com>
Date: Mon, 22 Apr 2013 09:51:18 +0400
Subject: Added range header parser

---
 src/cowboy_http.erl | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/cowboy_req.erl  |  2 ++
 2 files changed, 84 insertions(+)

diff --git a/src/cowboy_http.erl b/src/cowboy_http.erl
index b958020..5877ae1 100644
--- a/src/cowboy_http.erl
+++ b/src/cowboy_http.erl
@@ -37,6 +37,7 @@
 -export([token_ci/2]).
 -export([quoted_string/2]).
 -export([authorization/2]).
+-export([range/1]).
 
 %% Decoding.
 -export([te_chunked/2]).
@@ -847,6 +848,64 @@ authorization_basic_password(<<>>, Fun, Acc) ->
 authorization_basic_password(<<C, Rest/binary>>, Fun, Acc) ->
 	authorization_basic_password(Rest, Fun, <<Acc/binary, C>>).
 
+%% @doc Parse range header according rfc 2616.
+-spec range(binary()) -> {Unit, [Range]} | {error, badarg} when
+		Unit :: binary(),
+		Range :: {non_neg_integer(), non_neg_integer() | infinity} | neg_integer().
+range(Data) ->
+	cowboy_http:token_ci(Data, fun range/2).
+
+range(Data, Token) ->
+	whitespace(Data,
+		fun(<<"=", Rest/binary>>) ->
+			case cowboy_http:list(Rest, fun range_beginning/2) of
+				{error, badarg} ->
+					{error, badarg};
+				Ranges ->
+					{Token, Ranges}
+			end;
+		   (_) ->
+			{error, badarg}
+		end).
+
+range_beginning(Data, Fun) ->
+	range_digits(Data, suffix,
+		fun(D, RangeBeginning) ->
+			range_ending(D, Fun, RangeBeginning)
+		end).
+
+range_ending(Data, Fun, RangeBeginning) ->
+	whitespace(Data,
+		fun(<<"-", R/binary>>) ->
+			case RangeBeginning of
+				suffix ->
+					range_digits(R, fun(D, RangeEnding) -> Fun(D, -RangeEnding) end);
+				_ ->
+					range_digits(R, infinity,
+						fun(D, RangeEnding) ->
+							Fun(D, {RangeBeginning, RangeEnding})
+						end)
+			end;
+		   (_) ->
+			{error, badarg}
+		end).
+
+-spec range_digits(binary(), fun()) -> any().
+range_digits(Data, Fun) ->
+	whitespace(Data,
+		fun(D) ->
+			digits(D, Fun)
+		end).
+
+-spec range_digits(binary(), any(), fun()) -> any().
+range_digits(Data, Default, Fun) ->
+	whitespace(Data,
+		fun(<< C, Rest/binary >>) when C >= $0, C =< $9 ->
+			digits(Rest, Fun, C - $0);
+		   (_) ->
+			Fun(Data, Default)
+		end).
+
 %% Decoding.
 
 %% @doc Decode a stream of chunks.
@@ -1355,4 +1414,27 @@ http_authorization_test_() ->
 		authorization(<<" some_secret_key">>, <<"bearer">>))
 	].
 
+http_range_test_() ->
+	Tests = [
+		{<<"bytes=1-20">>,
+			{<<"bytes">>, [{1, 20}]}},
+		{<<"bytes=-100">>,
+			{<<"bytes">>, [-100]}},
+		{<<"bytes=1-">>,
+			{<<"bytes">>, [{1, infinity}]}},
+		{<<"bytes=1-20,30-40,50-">>,
+			{<<"bytes">>, [{1, 20}, {30, 40}, {50, infinity}]}},
+		{<<"bytes = 1 - 20 , 50 - , - 300 ">>,
+			{<<"bytes">>, [{1, 20}, {50, infinity}, -300]}},
+		{<<"bytes=1-20,-500,30-40">>,
+			{<<"bytes">>, [{1, 20}, -500, {30, 40}]}},
+		{<<"test=1-20,-500,30-40">>,
+			{<<"test">>, [{1, 20}, -500, {30, 40}]}},
+		{<<"bytes=-">>,
+			{error, badarg}},
+		{<<"bytes=-30,-">>,
+			{error, badarg}}
+	],
+	[fun() -> R = range(V) end ||{V, R} <- Tests].
+
 -endif.
diff --git a/src/cowboy_req.erl b/src/cowboy_req.erl
index 11b0e26..1817ab0 100644
--- a/src/cowboy_req.erl
+++ b/src/cowboy_req.erl
@@ -445,6 +445,8 @@ parse_header(Name, Req, Default)
 		when Name =:= <<"if-modified-since">>;
 			Name =:= <<"if-unmodified-since">> ->
 	parse_header(Name, Req, Default, fun cowboy_http:http_date/1);
+parse_header(Name = <<"range">>, Req, Default) ->
+	parse_header(Name, Req, Default, fun cowboy_http:range/1);
 parse_header(Name, Req, Default)
 		when Name =:= <<"sec-websocket-protocol">>;
 			Name =:= <<"x-forwarded-for">> ->
-- 
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