Add support of the 'Vary' header in response

With this patch, Yaws will add 'Accept-Encoding' in 'Vary' header if the
support of gzip compression is enabled or if the response is compressed.
The 'Vary' header can be set using 'yaws:outh_set_vary(Fields)' or by
returning '{header, {vary, Fields}}' from scripts (where Fields is a list
of header names).

doc/yaws.tex

@@ -1653,8 +1653,51 @@ \section{All out/1 return values}
   stream data, in this case, the response is not chunked encoded.
 
 
-\item \verb+{header, H}+ Accumulates a HTTP header. Used by for
-  example the \verb+yaws_api:setcookie/2-6+ function.
+\item \verb+{header, H}+ Accumulates a HTTP header. The trailing CRNL which is
+  supposed to end all HTTP headers must NOT be added. It is added by the server.
+  The following list of headers are given special treatment.
+
+  \begin{itemize}
+    \item \verb+{connection, What}+ - This sets the Connection: header. If
+      \textit{What} is the special value \textit{\"close\"}, the connection will
+      be closed once the yaws page is delivered to the client.
+    \item \verb+{server, What}+ - Sets the \textit{Server:} header. By setting
+      this header, the server's signature will be dynamically overloaded.
+    \item \verb+{location, What}+ - Sets the \textit{Location:} header. This
+      header is typically combined with the \textit{\{status, 302\}} return
+      value.
+    \item \verb+{cache_control, What}+ - Sets the \textit{Cache-Control:}
+      header.
+    \item \verb+{expires, What}+ - Sets the \textit{Expires:} header.
+    \item \verb+{date, What}+ - Sets the \textit{Date:} header.
+    \item \verb+{allow, What}+ - Sets the \textit{Allow:} header.
+    \item \verb+{last_modified, What}+ - Sets the \textit{Last-Modified:}
+      header.
+    \item \verb+{etag, What}+ - Sets the \textit{Etag:} header.
+    \item \verb+{set_cookie, What}+ - Prepends a \textit{Set-Cookie:} header to
+      the list of previously set \textit{Set-Cookie} headers.
+    \item \verb+{content_range, What}+ - Sets the \textit{Content-Range:}
+      header.
+    \item \verb+{content_type, What}+ - Sets the \textit{Content-Type:} header.
+    \item \verb+{content_encoding, What}+ - Sets the \textit{Content-Encoding:}
+      header. If this header is defined, no deflate is performed by \Yaws\. So
+      you can compress data by yourself.
+    \item \verb+{content_length, What}+ - Normally \Yaws\ will ship Yaws pages
+      using \textit{Transfer-Encoding: chunked}. This is because we generally
+      can't know how long a yaws page will be. If we for some reason want to
+      force a \textit{Content-Length:} header (and we actually do know the
+      length of the content, we can force yaws to not ship the page chunked.
+    \item \verb+{transfer_encoding, What}+ - Sets the
+      \textit{Transfer-Encoding:} header.
+    \item \verb+{www_authenticate, What}+ - Sets the \textit{WWW-Authenticate:}
+      header.
+    \item \verb+{vary, What}+ - Sets the \textit{Vary:} header.
+  \end{itemize}
+
+  All other headers must be added using the normal HTTP syntax. Example:
+\begin{verbatim}
+{header, {"My-X-Header", "gadong"}} or {header, "My-X-Header: gadong"}
+\end{verbatim}
 
 \item \verb+{header, {H, erase}}+ A specific case of the previous
   directive; use this to remove a specific header from a response. For

include/yaws.hrl

@@ -347,6 +347,7 @@
           content_encoding,
           transfer_encoding,
           www_authenticate,
+          vary,
           other                % misc other headers
          }).
 

man/yaws_api.5

@@ -866,6 +866,10 @@ Sets the Transfer-Encoding: header.
 
 Sets the WWW-Authenticate: header.
 
+\fI{vary, What}\fR
+
+Sets the Vary: header.
+
 
 All other headers must be added using the normal HTTP syntax.
 Example:

src/yaws.erl

@@ -51,6 +51,7 @@
          outh_set_dcc/2,
          outh_set_transfer_encoding_off/0,
          outh_set_auth/1,
+         outh_set_vary/1,
          outh_clear_headers/0,
          outh_fix_doclose/0,
          dcc/2]).
@@ -68,7 +69,8 @@
          make_www_authenticate_header/1,
          make_etag/1,
          make_content_type_header/1,
-         make_date_header/0]).
+         make_date_header/0,
+         make_vary_header/1]).
 
 -export([outh_get_status_code/0,
          outh_get_contlen/0,
@@ -79,6 +81,7 @@
          outh_get_content_encoding/0,
          outh_get_content_encoding_header/0,
          outh_get_content_type/0,
+         outh_get_vary_fields/0,
          outh_serialize/0]).
 
 -export([accumulate_header/1, headers_to_str/1,
@@ -1120,6 +1123,10 @@ outh_set_auth(Headers) ->
          end,
     put(outh, H2).
 
+outh_set_vary(Fields) ->
+    put(outh, (get(outh))#outh{vary = make_vary_header(Fields)}),
+    ok.
+
 outh_fix_doclose() ->
     H = get(outh),
     if
@@ -1307,6 +1314,12 @@ make_date_header() ->
             H
     end.
 
+make_vary_header(Fields) ->
+    case lists:member("*", Fields) of
+        true  -> ["Vary: ", "*", "\r\n"];
+        false -> ["Vary: ", join_sep(Fields, ", "), "\r\n"]
+    end.
+
 
 
 %% access functions into the outh record
@@ -1346,6 +1359,12 @@ outh_get_content_type() ->
         [_, Mime, _] -> Mime
     end.
 
+outh_get_vary_fields() ->
+    case (get(outh))#outh.vary of
+        undefined      -> [];
+        [_, Fields, _] -> split_sep(Fields, $,)
+    end.
+
 outh_serialize() ->
     H = get(outh),
     Code = case H#outh.status of
@@ -1382,6 +1401,26 @@ outh_serialize() ->
                           end,
                 {LM, E, CC}
         end,
+
+    %% Add 'Accept-Encoding' in the 'Vary:' header if the compression is enabled
+    %% or if the response is compressed _AND_ if the response has a non-empty
+    %% body.
+    SC=get(sc),
+    Vary = case (?sc_has_deflate(SC) orelse H#outh.encoding == deflate) of
+               true when H#outh.contlen /= undefined, H#outh.contlen /= 0;
+                         H#outh.act_contlen /= undefined, H#outh.act_contlen /= 0 ->
+                   Fields = outh_get_vary_fields(),
+                   Fun    = fun("*") -> true;
+                               (F)   -> (to_lower(F) == "accept-encoding")
+                            end,
+                   case lists:any(Fun, Fields) of
+                       true  -> H#outh.vary;
+                       false -> make_vary_header(["Accept-Encoding"|Fields])
+                   end;
+               _ ->
+                   H#outh.vary
+           end,
+
     Headers = [noundef(H#outh.connection),
                noundef(H#outh.server),
                noundef(H#outh.location),
@@ -1398,6 +1437,7 @@ outh_serialize() ->
                noundef(H#outh.set_cookie),
                noundef(H#outh.transfer_encoding),
                noundef(H#outh.www_authenticate),
+               noundef(Vary),
                noundef(H#outh.other)],
     {StatusLine, Headers}.
 
@@ -1530,6 +1570,11 @@ accumulate_header({www_authenticate, What}) ->
 accumulate_header({"WWW-Authenticate", What}) ->
     accumulate_header({www_authenticate, What});
 
+accumulate_header({vary, What}) ->
+    put(outh, (get(outh))#outh{vary = ["Vary: ", What, "\r\n"]});
+accumulate_header({"Vary", What}) ->
+    accumulate_header({vary, What});
+
 %% non-special headers (which may be special in a future Yaws version)
 accumulate_header({Name, What}) when is_list(Name) ->
     H = get(outh),
@@ -1589,7 +1634,9 @@ erase_header(transfer_encoding) ->
 erase_header(www_authenticate) ->
     put(outh, (get(outh))#outh{www_authenticate=undefined});
 erase_header(location) ->
-    put(outh, (get(outh))#outh{location=undefined}).
+    put(outh, (get(outh))#outh{location=undefined});
+erase_header(vary) ->
+    put(outh, (get(outh))#outh{vary=undefined}).
 
 getuid() ->
     case os:type() of

test/t5/app_test.erl

@@ -24,17 +24,32 @@ start() ->
 deflate_disabled() ->
     io:format("deflate_disabled\n", []),
 
-    %% Static content (and cached)
+    %% Static content (and cached) - Not supported by server
     Uri1 = "http://localhost:8000/1000.txt",
     ?line {ok, "200", Hdrs1, _} =
         ibrowse:send_req(Uri1, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs1),
+    ?line undefined = proplists:get_value("Vary", Hdrs1),
 
-    %% Dynamic content
+    %% Dynamic content - Not supported by server
     Uri2 = "http://localhost:8000/index.yaws",
     ?line {ok, "200", Hdrs2, _} =
         ibrowse:send_req(Uri2, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs2),
+    ?line undefined = proplists:get_value("Vary", Hdrs2),
+
+    %% Static content (and cached) - Not supported by client
+    Uri3 = "http://localhost:8001/1000.txt",
+    ?line {ok, "200", Hdrs3, _} =
+        ibrowse:send_req(Uri3, [], get),
+    ?line undefined = proplists:get_value("Content-Encoding", Hdrs3),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs3),
+
+    %% Dynamic content - Not supported by client
+    Uri4 = "http://localhost:8001/index.yaws",
+    ?line {ok, "200", Hdrs4, _} = ibrowse:send_req(Uri4, [], get),
+    ?line undefined = proplists:get_value("Content-Encoding", Hdrs4),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs4),
     ok.
 
 deflate_enabled() ->
@@ -45,6 +60,7 @@ deflate_enabled() ->
     ?line {ok, "200", Hdrs1, Body1} =
         ibrowse:send_req(Uri1, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line "gzip" = proplists:get_value("Content-Encoding", Hdrs1),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs1),
     ?line true = is_binary(zlib:gunzip(Body1)),
 
     %% Partial content is not compressed for small (and catched) files
@@ -54,12 +70,14 @@ deflate_enabled() ->
                                 {"Range", "bytes=100-499"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs2),
     ?line "400" = proplists:get_value("Content-Length", Hdrs2),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs2),
 
     %% Dynamic content
     Uri3 = "http://localhost:8001/index.yaws",
     ?line {ok, "200", Hdrs3, Body3} =
         ibrowse:send_req(Uri3, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line "gzip" = proplists:get_value("Content-Encoding", Hdrs3),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs3),
     ?line true = is_binary(zlib:gunzip(Body3)),
     ok.
 
@@ -73,25 +91,29 @@ deflate_empty_response() ->
         ibrowse:send_req(Uri1, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs1),
     ?line "0" = proplists:get_value("Content-Length", Hdrs1),
+    ?line undefined = proplists:get_value("Vary", Hdrs1),
 
     Uri2 = "http://localhost:8001/0.txt",
     ?line {ok, "200", Hdrs2, _} =
         ibrowse:send_req(Uri2, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs2),
     ?line "0" = proplists:get_value("Content-Length", Hdrs2),
+    ?line undefined = proplists:get_value("Vary", Hdrs2),
 
     %% Dynamic content
     Uri3 = "http://localhost:8000/emptytest",
     ?line {ok, "200", Hdrs3, _} =
         ibrowse:send_req(Uri3, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs3),
     ?line "0" = proplists:get_value("Content-Length", Hdrs3),
+    ?line undefined = proplists:get_value("Vary", Hdrs3),
 
     Uri4 = "http://localhost:8001/emptytest",
     ?line {ok, "200", Hdrs4, _} =
         ibrowse:send_req(Uri4, [{"Accept-Encoding", "gzip, deflate"}], get),
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs4),
     ?line "0" = proplists:get_value("Content-Length", Hdrs4),
+    ?line undefined = proplists:get_value("Vary", Hdrs4),
     ok.
 
 
@@ -105,6 +127,7 @@ deflate_streamcontent() ->
     ?line "gzip" = proplists:get_value("Content-Encoding", Hdrs1),
     ?line "chunked" = proplists:get_value("Transfer-Encoding", Hdrs1),
     ?line undefined = proplists:get_value("Content-Length", Hdrs1),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs1),
 
     %% Partial content is not compressed for large files
     Uri2 = "http://localhost:8001/10000.txt",
@@ -114,6 +137,7 @@ deflate_streamcontent() ->
     ?line undefined = proplists:get_value("Content-Encoding", Hdrs2),
     ?line undefined = proplists:get_value("Transfer-Encoding", Hdrs2),
     ?line "100"     = proplists:get_value("Content-Length", Hdrs2),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs2),
 
     %% Dynamic content (chunked)
     Uri3 = "http://localhost:8001/streamtest",
@@ -122,6 +146,7 @@ deflate_streamcontent() ->
     ?line "gzip" = proplists:get_value("Content-Encoding", Hdrs3),
     ?line "chunked" = proplists:get_value("Transfer-Encoding", Hdrs3),
     ?line undefined = proplists:get_value("Content-Length", Hdrs3),
+    ?line "Accept-Encoding" = proplists:get_value("Vary", Hdrs3),
     ok.