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From "Oleg Kalnichevski (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HTTPCLIENT-1855) Digest auth: Nonce counter not incremented after reuse
Date Fri, 10 Nov 2017 12:49:00 GMT

    [ https://issues.apache.org/jira/browse/HTTPCLIENT-1855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16247432#comment-16247432

Oleg Kalnichevski commented on HTTPCLIENT-1855:

Fundamentally the issue is about some state information shared by multiple contexts / execution
threads, not about caching. Essentially what you want to multiple contexts to share is not
the DIGEST scheme state, but only a count associated with a particular nonce. Misusing or
abusing the auth cache functionality sounds wrong to me, especially given it requires forcing
a cache update on each request / response exchange. There are better ways of achieving the
same goal, for instance, by making DigestScheme instances share some common structure.


> Digest auth: Nonce counter not incremented after reuse
> ------------------------------------------------------
>                 Key: HTTPCLIENT-1855
>                 URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1855
>             Project: HttpComponents HttpClient
>          Issue Type: Bug
>          Components: HttpClient (classic)
>    Affects Versions: 4.5.2
>            Reporter: Alessandro Gherardi
>         Attachments: HttpClient5Digest.java, HttpClientDigest.java, httpclient5.log,
> I have a client app using httpclient 4.5.2 with BasicCredentialsProvider and BasicAuthCache.
and web server that requires HTTP digest authentication. 
> The client sends 3 requests to the web server. 
> When the app sends the first request, the server returns an HTTP 401 with a digest challenge.
httpclient automatically retries the request with the Authorization header. The header contains
the nonce returned by the server and a nonce counter (nc) of 1. The retry succeeds and httpclient
caches the DigestScheme.
> For the second request, httpclient uses the cached DigestScheme to calculate the Authorization
header pre-emptively. The header contains the same nonce and specifies a nonce counter of
2. The request succeed without requiring a retry.
> For the third request, httpclient uses the cached DigestScheme to calculate the Authorization
header pre-emptively. Even though the header contains the same nonce, the nonce counter is
set to 2 again. This causes the server to return a 401. httpclient should have incremented
the nonce counter to 3.
> I believe that the root cause of this problem is that, although DigestScheme increases
the nonceCount field every time the authenticate() method is called, HttpAuthenticator does
not re-cache DigestScheme after reusing it. The re-cache is needed because BasicAuthCache
stores DigestScheme in serialized format.

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