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From Nathan Vander Wilt <nat...@gmail.com>
Subject Re: Sporadic _session/_users lookup failures
Date Sun, 18 Nov 2012 00:55:33 GMT
Figured this out, it is indeed a bug in CouchDB's cookie processing: https://issues.apache.org/jira/browse/COUCHDB-1607
Basically, if the cookie handler happens to generate a cookie signature that starts with any
colon(s) it will be rejected when the client sends it back. This explains the random/sporadic
nature of the bug.

hth,
-nvw




On Nov 17, 2012, at 1:13 PM, Nathan Vander Wilt wrote:

> Got curious, so I retested with two changes:
> - using a local build of CouchDB 1.2.0 (as I remembered Iris Couch has some additional
auth handlers active)
> - check if the cookie is accepted later on, after the initial failed request — to see
if the issue is temporary
> 
> Result?
> Still experiencing the same problem.
> 
> So I'm leaning more to suspect an occasional problem with cookie *generation*, than to
intermittent failures of _users look up or timestamp checking — otherwise I would expect
proffering the cookie a second time, while it still had half a minute left, might have worked.
> 
> My test script here, requires node, `npm install fermata` and appropriate user/password
setup: https://gist.github.com/4100307
> I recommend letting it run simultaneously in a whole bunch of terminal tabs to get a
result quicker — sometimes it continues happily for even an hour or so but it seems eventually
the problem strikes every tab's session. Log below from the first failure I got with the revised
test.
> 
> hth,
> -natevw
> 
> 
> ```
> /my/shell$ DB_SERVER=http://localhost:5984 node backend/session_test.js
> Logged in.      AuthSession=YWxpY2U6NTBBN0Y4Njg6Amsau3CBhrOxcl8NPRW1LsUdBqs
> 
> Sending cookie: AuthSession=YWxpY2U6NTBBN0Y4Njg6Amsau3CBhrOxcl8NPRW1LsUdBqs at 2012-11-17T20:50:14.194Z
> Recv'd cookie: AuthSession=YWxpY2U6NTBBN0Y4ODY629p85Iq4vUndBunYBQGyszCgAXI
> {"ok":true,"userCtx":{"name":"alice","roles":["student","teacher"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"cookie"}}
> 
> 
> Sending cookie: AuthSession=YWxpY2U6NTBBN0Y4ODY629p85Iq4vUndBunYBQGyszCgAXI at 2012-11-17T20:50:44.193Z
> Recv'd cookie: AuthSession=YWxpY2U6NTBBN0Y4QTQ6HBAugsm_iCPtwKXgwZFDaw1Lz6g
> {"ok":true,"userCtx":{"name":"alice","roles":["student","teacher"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"cookie"}}
> 
> # …snip…
> 
> Sending cookie: AuthSession=YWxpY2U6NTBBN0Y5QjI6WYCCehzuxW7gGFFFGxAv4QsLiZ4 at 2012-11-17T20:55:44.192Z
> Recv'd cookie: AuthSession=YWxpY2U6NTBBN0Y5RDA6Ot-kqL0ATZPL8fnWZRTMyegLxjU
> {"ok":true,"userCtx":{"name":"alice","roles":["student","teacher"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"cookie"}}
> 
> 
> Sending cookie: AuthSession=YWxpY2U6NTBBN0Y5RDA6Ot-kqL0ATZPL8fnWZRTMyegLxjU at 2012-11-17T20:56:14.192Z
> {"ok":true,"userCtx":{"name":null,"roles":["_admin"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"default"}}
> 
> 
> Sending cookie: AuthSession=YWxpY2U6NTBBN0Y5RDA6Ot-kqL0ATZPL8fnWZRTMyegLxjU at 2012-11-17T20:56:44.192Z
> {"ok":true,"userCtx":{"name":null,"roles":["_admin"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"default"}}
> 
> 
> 
> /Users/natevw/Desktop/Clients/Inquirium/readi-sensemaker-prototype/backend/session_test.js:34
>        if (brokt) throw "Previous request logged out!";
>                   ^
> Previous request logged out!
> ```
> 
> 
> 
> 
> 
> 
> On Nov 17, 2012, at 11:41 AM, Nathan Vander Wilt wrote:
> 
>> I'm trying to diagnose an issue we're having with users getting unexpectedly logged
out of an app. This is affecting real-world use, interrupting work when our heartbeat check
unexpectedly detects the API is unusable.
>> 
>> I've reduced this to a test script I can run. The setup is as follows:
>> - set _config/couch_httpd_auth/timeout to 90
>> - run a script that logs in, then refreshes the AuthSession cookie every 30 seconds
via /_session
>> 
>> What happens is shown below. After just a few or perhaps a whole lot of correct responses
to the _session request, all of a sudden the user appears to be logged out!
>> 
>> ```
>> Logged in.      AuthSession=YWxpY2U6NTBBN0RBMjE6zpoSjz9lYJJ1tse3bpTvuS7H84Q
>> 
>> Sending cookie: AuthSession=YWxpY2U6NTBBN0RBMjE6zpoSjz9lYJJ1tse3bpTvuS7H84Q at 2012-11-17T18:41:09.250Z
>> Recv'd cookie: AuthSession=YWxpY2U6NTBBN0RBM0Y6SqE-uad8GVVtE5nwLk5Woh6pW0U
>> {"ok":true,"userCtx":{"name":"alice","roles":["student","teacher"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"cookie"}}
>> 
>> // seemingly random duration passes, script often continues logging every 30 seconds
for a while…
>> 
>> Sending cookie: AuthSession=YWxpY2U6NTBBN0RDQjU66jE52YKejdDLVZZ_N5oPL74Gsl0 at 2012-11-17T18:52:09.250Z
>> Recv'd cookie: AuthSession=YWxpY2U6NTBBN0RDRDM6Ogig0a9RpBMdZ4hHjHuet2KKurI
>> {"ok":true,"userCtx":{"name":"alice","roles":["student","teacher"]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"],"authenticated":"cookie"}}
>> 
>> 
>> Sending cookie: AuthSession=YWxpY2U6NTBBN0RDRDM6Ogig0a9RpBMdZ4hHjHuet2KKurI at 2012-11-17T18:52:39.250Z
>> {"ok":true,"userCtx":{"name":null,"roles":[]},"info":{"authentication_db":"_users","authentication_handlers":["oauth","cookie","default"]}}
>> 
>> 
>> 
>> /Users/natevw/Desktop/Clients/Inquirium/readi-sensemaker-prototype/backend/session_test.js:33
>>       if (!~d.data.indexOf('alice')) throw "Logged out!";
>>                                      ^
>> Logged out!
>> ```
>> 
>> The last cookie sent still has signed session data "alice:50A7DCD3" (2012-11-17T18:52:03Z
timestamp on server) which should still be valid for about another minute at the time of request.
But there is no "authenticated" field and "userCtx.name" turns up `null`! Why would this be?
>> 
>> 
>> To add to the intrigue, I just received a report of some (at first glance unrelated)
initial login trouble. Inspecting the logs, I found this:
>> 
>> GET /_users/org.couchdb.user%3Abob 404
>> GET /_users/org.couchdb.user%3Abob 404
>> // … time passes, with no intervening PUT/POST requests to the _users DB
>> GET /_users/org.couchdb.user%3Abob 200
>> 
>> This document would have been accessed using cookie credentials for user `bob`...again
we see an intermittent issue with either looking up a user or retaining a logged in state.
(In this case the cookie would have been only a few millseconds old.)
>> 
>> 
>> I strongly suspect this is a bug somewhere within CouchDB's the cookie handling path,
or user lookup path — but what and where in the code could be going wrong? Testing so far
has been against 1.2.0 as deployed on Iris Couch.
>> 
>> thanks,
>> -natevw
> 


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