Add functions for getting and setting response headers

doc/src/manual/cowboy_req.asciidoc

@@ -67,7 +67,10 @@ Request body:
 Response:
 
 * link:man:cowboy_req:set_resp_cookie(3)[cowboy_req:set_resp_cookie(3)] - Set a cookie
+* link:man:cowboy_req:resp_header(3)[cowboy_req:resp_header(3)] - Access the named HTTP header set for the response
+* link:man:cowboy_req:resp_headers(3)[cowboy_req:resp_headers(3)] - Access HTTP headers set for the response
 * link:man:cowboy_req:set_resp_header(3)[cowboy_req:set_resp_header(3)] - Set a response header
+* link:man:cowboy_req:set_resp_headers(3)[cowboy_req:set_resp_headers(3)] - Set several response headers
 * link:man:cowboy_req:has_resp_header(3)[cowboy_req:has_resp_header(3)] - Is the given response header set?
 * link:man:cowboy_req:delete_resp_header(3)[cowboy_req:delete_resp_header(3)] - Delete a response header
 * link:man:cowboy_req:set_resp_body(3)[cowboy_req:set_resp_body(3)] - Set the response body

doc/src/manual/cowboy_req.resp_header.asciidoc

@@ -0,0 +1,61 @@
+= cowboy_req:resp_header(3)
+
+== Name
+
+cowboy_req:resp_header - Access the named HTTP header set for the response
+
+== Description
+
+[source,erlang]
+----
+resp_header(Name, Req)          -> resp_header(Name, Req, undefined)
+resp_header(Name, Req, Default) -> binary() | Default
+
+Name    :: binary()
+Req     :: cowboy_req:req()
+Default :: any()
+----
+
+Return the currently set response header value for the given HTTP header.
+
+== Arguments
+
+Name::
+
+Desired response HTTP header name as a binary.
+
+Req::
+
+The Req object.
+
+Default::
+
+Default value returned when the header is missing.
+
+== Return value
+
+The binary value for the given HTTP header name.
+
+== Changelog
+
+* *2.0*: Function introduced.
+
+== Examples
+
+.Get the response header with the given name
+[source,erlang]
+----
+HeaderValue = cowboy_req:resp_header(<<"x-test-header">>, Req).
+----
+
+.Get the response header with the given name and a default
+[source,erlang]
+----
+HeaderValue = cowboy_req:resp_header(<<"x-test-header">>, Req, <<"bar">>).
+----
+
+== See also
+
+link:man:cowboy_req(3)[cowboy_req(3)],
+link:man:cowboy_req:set_resp_headers(3)[cowboy_req:resp_headers(3)]
+link:man:cowboy_req:set_resp_header(3)[cowboy_req:set_resp_header(3)]

doc/src/manual/cowboy_req.resp_headers.asciidoc

@@ -0,0 +1,45 @@
+= cowboy_req:resp_headers(3)
+
+== Name
+
+cowboy_req:resp_headers - Access HTTP headers set for the response
+
+== Description
+
+[source,erlang]
+----
+resp_headers(Req) -> cowboy:http_headers()
+
+Req :: cowboy_req:req()
+----
+
+Return all HTTP response headers.
+
+== Arguments
+
+Req::
+
+The Req object.
+
+== Return value
+
+Headers are returned as a map with keys being lowercase
+binary strings, and values as binary strings.
+If no response headers have been added the empty map is returned.
+
+== Changelog
+
+* *2.0*: Function introduced.
+
+== Examples
+
+.Get all response headers
+[source,erlang]
+----
+Headers = cowboy_req:resp_headers(Req).
+----
+
+== See also
+
+link:man:cowboy_req(3)[cowboy_req(3)],
+link:man:cowboy_req:set_resp_headers(3)[cowboy_req:set_resp_headers(3)]

doc/src/manual/cowboy_req.set_resp_headers.asciidoc

@@ -0,0 +1,51 @@
+= cowboy_req:set_resp_headers(3)
+
+== Name
+
+cowboy_req:set_resp_headers - Set several response headers
+
+== Description
+
+[source,erlang]
+----
+set_resp_headers(Headers, Req) -> cowboy_req:req()
+
+Headers :: cowboy:http_headers()
+Req     :: cowboy_req:req()
+----
+
+Add all given headers to the response headers.
+If a given header key already exists in the currently set
+response-header map the given value will overwrite the old.
+
+== Arguments
+
+Headers::
+
+A map with keys and values as binary strings.
+Key values should be lowercase to function properly.
+
+Req::
+
+The Req object.
+
+== Return value
+
+A request object updated with the given response headers.
+
+== Changelog
+
+* *2.0*: Function introduced.
+
+== Examples
+
+.Get all response headers
+[source,erlang]
+----
+Req1 = cowboy_req:set_resp_headers(#{<<"x-header-test">> => <<"1">>}, Req0).
+----
+
+== See also
+
+link:man:cowboy_req(3)[cowboy_req(3)],
+link:man:cowboy_req:resp_headers(3)[cowboy_req:resp_headers(3)]

src/cowboy_req.erl

@@ -59,8 +59,11 @@
 %% Response.
 -export([set_resp_cookie/3]).
 -export([set_resp_cookie/4]).
+-export([resp_header/2]).
+-export([resp_header/3]).
+-export([resp_headers/1]).
 -export([set_resp_header/3]).
-%% @todo set_resp_headers/2
+-export([set_resp_headers/2]).
 -export([has_resp_header/2]).
 %% @todo resp_header
 -export([delete_resp_header/2]).
@@ -570,6 +573,31 @@ set_resp_header(Name, Value, Req=#{resp_headers := RespHeaders}) ->
 set_resp_header(Name,Value, Req) ->
 	Req#{resp_headers => #{Name => Value}}.
 
+-spec set_resp_headers(cowboy:http_headers(), Req)
+	-> Req when Req::req().
+set_resp_headers(Headers, Req=#{resp_headers := RespHeaders}) ->
+	Req#{resp_headers => maps:merge(RespHeaders, Headers)};
+set_resp_headers(Headers, Req) ->
+	Req#{resp_headers => Headers}.
+
+
+-spec resp_header(binary(), req()) -> binary() | undefined.
+resp_header(Name, Req) ->
+	resp_header(Name, Req, undefined).
+
+-spec resp_header(binary(), req(), Default)
+	-> binary() | Default when Default::any().
+resp_header(Name, #{resp_headers := Headers}, Default) ->
+	maps:get(Name, Headers, Default);
+resp_header(_, #{}, Default) ->
+	Default.
+
+-spec resp_headers(req()) -> cowboy:http_headers().
+resp_headers(#{resp_headers := RespHeaders}) ->
+	RespHeaders;
+resp_headers(#{}) ->
+	#{}.
+
 -spec set_resp_body(resp_body(), Req) -> Req when Req::req().
 set_resp_body(Body, Req) ->
 	Req#{resp_body => Body}.

test/handlers/resp_h.erl

@@ -25,6 +25,29 @@ do(<<"set_resp_cookie4">>, Req0, Opts) ->
 do(<<"set_resp_header">>, Req0, Opts) ->
 	Req = cowboy_req:set_resp_header(<<"content-type">>, <<"text/plain">>, Req0),
 	{ok, cowboy_req:reply(200, #{}, "OK", Req), Opts};
+do(<<"set_resp_headers">>, Req0, Opts) ->
+	Req = cowboy_req:set_resp_headers(#{<<"x-header-test1">> => <<"test1">>, <<"x-header-test2">> => <<"test2">>}, Req0),
+	{ok, cowboy_req:reply(200, #{}, "OK", Req), Opts};
+do(<<"resp_headers">>, Req0, Opts) ->
+	Req1 = cowboy_req:set_resp_header(<<"x-header-test1">>, <<"test1">>, Req0),
+	Req2 = cowboy_req:set_resp_headers(#{<<"x-header-test2">> => <<"test2">>, <<"x-header-test3">> => <<"test3">>}, Req1),
+	Headers = cowboy_req:resp_headers(Req2),
+	true = maps:is_key(<<"x-header-test1">>, Headers),
+	true = maps:is_key(<<"x-header-test2">>, Headers),
+	true = maps:is_key(<<"x-header-test3">>, Headers),
+	{ok, cowboy_req:reply(200, #{}, "OK", Req2), Opts};
+do(<<"resp_header_defined">>, Req0, Opts) ->
+	Req1 = cowboy_req:set_resp_header(<<"x-header-test1">>, <<"test1">>, Req0),
+	<<"test1">> = cowboy_req:resp_header(<<"x-header-test1">>, Req1),
+	<<"test1">> = cowboy_req:resp_header(<<"x-header-test1">>, Req1, foo),
+	{ok, cowboy_req:reply(200, #{}, "OK", Req0), Opts};
+do(<<"resp_header_default">>, Req0, Opts) ->
+	undefined = cowboy_req:resp_header(<<"x-header-test1">>, Req0),
+	<<"ok">> = cowboy_req:resp_header(<<"x-header-test1">>, Req0, <<"ok">>),
+	{ok, cowboy_req:reply(200, #{}, "OK", Req0), Opts};
+do(<<"resp_headers_empty">>, Req0, Opts) ->
+	#{} = cowboy_req:resp_headers(Req0),
+	{ok, cowboy_req:reply(200, #{}, "OK", Req0), Opts};
 do(<<"set_resp_body">>, Req0, Opts) ->
 	Arg = cowboy_req:binding(arg, Req0),
 	Req1 = case Arg of

test/req_SUITE.erl

@@ -487,6 +487,25 @@ set_resp_header(Config) ->
 	true = lists:keymember(<<"content-type">>, 1, Headers),
 	ok.
 
+set_resp_headers(Config) ->
+	doc("Response using set_resp_headers."),
+	{200, Headers, <<"OK">>} = do_get("/resp/set_resp_headers", Config),
+	true = lists:keymember(<<"x-header-test1">>, 1, Headers),
+	true = lists:keymember(<<"x-header-test2">>, 1, Headers),
+	ok.
+
+resp_header(Config) ->
+	doc("Response header with/without default."),
+	{200, _, <<"OK">>} = do_get("/resp/resp_header_defined", Config),
+	{200, _, <<"OK">>} = do_get("/resp/resp_header_default", Config),
+	ok.
+
+resp_headers(Config) ->
+	doc("Get all response headers."),
+	{200, _, <<"OK">>} = do_get("/resp/resp_headers", Config),
+	{200, _, <<"OK">>} = do_get("/resp/resp_headers_empty", Config),
+	ok.
+
 set_resp_body(Config) ->
 	doc("Response using set_resp_body."),
 	{200, _, <<"OK">>} = do_get("/resp/set_resp_body", Config),