From cbd893d573e2b37baa50528f2d4a639f885ebefa Mon Sep 17 00:00:00 2001
From: "Damien F. Katz" <damien@apache.org>
Date: Tue, 27 Oct 2009 21:40:25 +0000
Subject: Make it harder to accidently terminate chunked resposnes by requiring
 callers to explicity call last_chunk(Req) and ignoring send_chunk calls with
 no data.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@830353 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_httpd.erl               | 18 ++++++++++++------
 src/couchdb/couch_httpd_misc_handlers.erl |  4 ++--
 src/couchdb/couch_httpd_show.erl          |  4 ++--
 3 files changed, 16 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/couchdb/couch_httpd.erl b/src/couchdb/couch_httpd.erl
index b28486fa..9ad39e2d 100644
--- a/src/couchdb/couch_httpd.erl
+++ b/src/couchdb/couch_httpd.erl
@@ -23,7 +23,7 @@
 -export([start_response_length/4, send/2]).
 -export([start_json_response/2, start_json_response/3, end_json_response/1]).
 -export([send_response/4,send_method_not_allowed/2,send_error/4, send_redirect/2,send_chunked_error/2]).
--export([send_json/2,send_json/3,send_json/4]).
+-export([send_json/2,send_json/3,send_json/4,last_chunk/1]).
 
 start_link() ->
     % read config and register for configuration changes
@@ -422,7 +422,14 @@ start_chunked_response(#httpd{mochi_req=MochiReq}=Req, Code, Headers) ->
     {ok, Resp}.
 
 send_chunk(Resp, Data) ->
-    Resp:write_chunk(Data),
+    case iolist_size(Data) of
+    0 -> ok; % do nothing
+    _ -> Resp:write_chunk(Data)
+    end,
+    {ok, Resp}.
+
+last_chunk(Resp) ->
+    Resp:write_chunk([]),
     {ok, Resp}.
 
 send_response(#httpd{mochi_req=MochiReq}=Req, Code, Headers, Body) ->
@@ -473,8 +480,7 @@ start_json_response(Req, Code, Headers) ->
 
 end_json_response(Resp) ->
     send_chunk(Resp, end_jsonp() ++ [$\n]),
-    %send_chunk(Resp, [$\n]),
-    send_chunk(Resp, []).
+    last_chunk(Resp).
 
 start_jsonp(Req) ->
     case get(jsonp) of
@@ -586,7 +592,7 @@ send_error(Req, Code, Headers, ErrorStr, ReasonStr) ->
 % give the option for list functions to output html or other raw errors
 send_chunked_error(Resp, {_Error, {[{<<"body">>, Reason}]}}) ->
     send_chunk(Resp, Reason),
-    send_chunk(Resp, []);
+    last_chunk(Resp);
 
 send_chunked_error(Resp, Error) ->
     {Code, ErrorStr, ReasonStr} = error_info(Error),
@@ -594,7 +600,7 @@ send_chunked_error(Resp, Error) ->
         {<<"error">>,  ErrorStr},
         {<<"reason">>, ReasonStr}]},
     send_chunk(Resp, ?l2b([$\n,?JSON_ENCODE(JsonError),$\n])),
-    send_chunk(Resp, []).
+    last_chunk(Resp).
 
 send_redirect(Req, Path) ->
      Headers = [{"Location", couch_httpd:absolute_uri(Req, Path)}],
diff --git a/src/couchdb/couch_httpd_misc_handlers.erl b/src/couchdb/couch_httpd_misc_handlers.erl
index 7e2d9ea2..fb761f5b 100644
--- a/src/couchdb/couch_httpd_misc_handlers.erl
+++ b/src/couchdb/couch_httpd_misc_handlers.erl
@@ -24,7 +24,7 @@
 
 -import(couch_httpd,
     [send_json/2,send_json/3,send_json/4,send_method_not_allowed/2,
-    start_json_response/2,send_chunk/2,end_json_response/1,
+    start_json_response/2,send_chunk/2,last_chunk/1,end_json_response/1,
     start_chunked_response/3, send_error/4]).
 
 % httpd global handlers
@@ -203,7 +203,7 @@ handle_log_req(#httpd{method='GET'}=Req) ->
         {"Content-Length", integer_to_list(length(Chunk))}
     ]),
     send_chunk(Resp, Chunk),
-    send_chunk(Resp, "");
+    last_chunk(Resp);
 handle_log_req(Req) ->
     send_method_not_allowed(Req, "GET").
 
diff --git a/src/couchdb/couch_httpd_show.erl b/src/couchdb/couch_httpd_show.erl
index 896c833e..fe8e2002 100644
--- a/src/couchdb/couch_httpd_show.erl
+++ b/src/couchdb/couch_httpd_show.erl
@@ -19,7 +19,7 @@
 
 -import(couch_httpd,
     [send_json/2,send_json/3,send_json/4,send_method_not_allowed/2,
-    start_json_response/2,send_chunk/2,send_chunked_error/2,
+    start_json_response/2,send_chunk/2,last_chunk/1,send_chunked_error/2,
     start_chunked_response/3, send_error/4]).
 
 handle_doc_show_req(#httpd{
@@ -365,7 +365,7 @@ finish_list(Req, QueryServer, Etag, FoldResult, StartFun, TotalRows) ->
             [<<"end">>, Chunks] = couch_query_servers:render_list_tail(QueryServer),
             send_non_empty_chunk(Resp, ?b2l(?l2b(Chunks)))
     end,
-    send_chunk(Resp, []).
+    last_chunk(Resp).
 
 
 render_head_for_empty_list(StartListRespFun, Req, Etag, null) ->
-- 
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