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From: KlausTrainer <git@git.apache.org>
To: dev@couchdb.apache.org
Reply-To: dev@couchdb.apache.org
References: <git-pr-172-couchdb@git.apache.org>
In-Reply-To: <git-pr-172-couchdb@git.apache.org>
Subject: [GitHub] couchdb pull request: Use cookie authentication during
 replication
Content-Type: text/plain
Message-Id: <20140311092013.D200593E753@tyr.zones.apache.org>
Date: Tue, 11 Mar 2014 09:20:13 +0000 (UTC)

Github user KlausTrainer commented on a diff in the pull request:

    https://github.com/apache/couchdb/pull/172#discussion_r10465907
  
    --- Diff: src/couch_replicator/src/couch_replicator_httpc.erl ---
    @@ -131,6 +171,90 @@ process_stream_response(ReqId, Worker, HttpDb, Params, Callback) ->
         end.
     
     
    +process_stream_response_headers(ReqId, Code, Headers, Worker, HttpDb, Params, Callback) ->
    +    StreamDataFun = fun() ->
    +        stream_data_self(HttpDb, Params, Worker, ReqId, Callback)
    +    end,
    +    ibrowse:stream_next(ReqId),
    +    try
    +        Ret = Callback(Code, Headers, StreamDataFun),
    +        release_worker(Worker, HttpDb),
    +        clean_mailbox_req(ReqId),
    +        Ret
    +    catch throw:{maybe_retry_req, Err} ->
    +        clean_mailbox_req(ReqId),
    +        maybe_retry(Err, Worker, HttpDb, Params, Callback)
    +    end.
    +
    +
    +maybe_start_new_session(HttpDb) ->
    +    case need_new_session(HttpDb) of
    +    false -> false;
    +    true -> start_new_session(HttpDb)
    +    end.
    +
    +
    +maybe_start_new_session(HttpDb, Worker) ->
    +    case need_new_session(HttpDb) of
    +    false -> false;
    +    true -> start_new_session(HttpDb, Worker)
    +    end.
    +
    +
    +need_new_session(#httpdb{credentials = undefined}) ->
    +    false;
    +
    +need_new_session(#httpdb{credentials = Credentials}) ->
    +    case ets:lookup(Credentials, cookie) of
    +    [] ->
    +        true;
    +    [{cookie, _, UpdatedAt}] ->
    +        %% As we don't know when the cookie will expire, we just decide
    +        %% that we want a new session if the current one is older than
    +        %% one minute.
    +        OneMinute = 60 * 1000000, % microseconds
    --- End diff --
    
    Yes, that's possible, but what advantage would it get us?  I had previously implemented it, but then threw it away again.  One disadvantage of that is that it makes us rely on clocks being synchronized, which is an assumption we probably like to avoid here.
    
    As of now, we unfortunately don't have any knowledge about the expiry time of a cookie here (there's only have the timestamp).  Choosing one minute seems like a good compromise to me, as it's unlikely that people will configuring a session timeout below that.  However, it might be good to consequently limit the session timeout to a minimum of one minute and document it appropriately.


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