Closes COUCHDB-334 - Add JSONP support to CouchDB

Use JSONP by providing a ?callback=function_name URL paramter for any URL
returning JSON data.



git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@774180 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 64 insertions, 5 deletions

diff --git a/src/couchdb/couch_db.hrl b/src/couchdb/couch_db.hrl
index c00792a8..0f7e344e 100644
--- a/src/couchdb/couch_db.hrl
+++ b/src/couchdb/couch_db.hrl
@@ -167,7 +167,8 @@
     include_docs = false,
     stale = false,
     multi_get = false,
-    ignore = false
+    ignore = false,
+    callback = nil
 }).
 
 -record(view_fold_helper_funs, {
diff --git a/src/couchdb/couch_httpd.erl b/src/couchdb/couch_httpd.erl
index 7a803c85..0f29bae7 100644
--- a/src/couchdb/couch_httpd.erl
+++ b/src/couchdb/couch_httpd.erl
@@ -386,8 +386,10 @@ send_json(Req, Code, Headers, Value) ->
         {"Content-Type", negotiate_content_type(Req)},
         {"Cache-Control", "must-revalidate"}
     ],
-    send_response(Req, Code, DefaultHeaders ++ Headers,
-                  list_to_binary([?JSON_ENCODE(Value), $\n])).
+    Body = list_to_binary(
+        [start_jsonp(Req), ?JSON_ENCODE(Value), end_jsonp(), $\n]
+    ),
+    send_response(Req, Code, DefaultHeaders ++ Headers, Body).
 
 start_json_response(Req, Code) ->
     start_json_response(Req, Code, []).
@@ -397,12 +399,66 @@ start_json_response(Req, Code, Headers) ->
         {"Content-Type", negotiate_content_type(Req)},
         {"Cache-Control", "must-revalidate"}
     ],
-    start_chunked_response(Req, Code, DefaultHeaders ++ Headers).
+    start_jsonp(Req), % Validate before starting chunked.
+    %start_chunked_response(Req, Code, DefaultHeaders ++ Headers).
+    {ok, Resp} = start_chunked_response(Req, Code, DefaultHeaders ++ Headers),
+    case start_jsonp(Req) of
+        [] -> ok;
+        Start -> send_chunk(Resp, Start)
+    end,
+    {ok, Resp}.
 
 end_json_response(Resp) ->
-    send_chunk(Resp, [$\n]),
+    send_chunk(Resp, end_jsonp() ++ [$\n]),
+    %send_chunk(Resp, [$\n]),
     send_chunk(Resp, []).
 
+start_jsonp(Req) ->
+    case get(jsonp) of
+        undefined -> put(jsonp, qs_value(Req, "callback", no_jsonp));
+        _ -> ok
+    end,
+    case get(jsonp) of
+        no_jsonp -> [];
+        [] -> [];
+        CallBack ->
+            try
+                validate_callback(CallBack),
+                CallBack ++ "("
+            catch
+                Error ->
+                    put(jsonp, no_jsonp),
+                    throw(Error)
+            end
+    end.
+
+end_jsonp() ->
+    Resp = case get(jsonp) of
+        no_jsonp -> [];
+        [] -> [];
+        _ -> ");"
+    end,
+    put(jsonp, undefined),
+    Resp.
+        
+validate_callback(CallBack) when is_binary(CallBack) ->
+    validate_callback(binary_to_list(CallBack));
+validate_callback([]) ->
+    ok;
+validate_callback([Char | Rest]) ->
+    case Char of
+        _ when Char >= $a andalso Char =< $z -> ok;
+        _ when Char >= $A andalso Char =< $Z -> ok;
+        _ when Char >= $0 andalso Char =< $9 -> ok;
+        _ when Char == $. -> ok;
+        _ when Char == $_ -> ok;
+        _ when Char == $[ -> ok;
+        _ when Char == $] -> ok;
+        _ ->
+            throw({bad_request, invalid_callback})
+    end,
+    validate_callback(Rest).
+
 
 error_info({Error, Reason}) when is_list(Reason) ->
     error_info({Error, ?l2b(Reason)});
diff --git a/src/couchdb/couch_httpd_view.erl b/src/couchdb/couch_httpd_view.erl
index 016a391a..8db561ac 100644
--- a/src/couchdb/couch_httpd_view.erl
+++ b/src/couchdb/couch_httpd_view.erl
@@ -270,6 +270,8 @@ parse_view_param("reduce", Value) ->
     [{reduce, parse_bool_param(Value)}];
 parse_view_param("include_docs", Value) ->
     [{include_docs, parse_bool_param(Value)}];
+parse_view_param("callback", _) ->
+    []; % Verified in the JSON response functions
 parse_view_param(Key, Value) ->
     [{extra, {Key, Value}}].