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From "bitfire (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HTTPCLIENT-1489) Multiple, comma-separated challenges in WWW-Authenticate are not recognized
Date Sat, 22 Mar 2014 16:08:42 GMT

    [ https://issues.apache.org/jira/browse/HTTPCLIENT-1489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13944133#comment-13944133
] 

bitfire edited comment on HTTPCLIENT-1489 at 3/22/14 4:07 PM:
--------------------------------------------------------------

I'm happy that I've never had to bother with NTLM authentication. According to http://www.innovation.ch/personal/ronald/ntlm.html,
the syntax is always either
{noformat}
WWW-Authenticate: NTLM <base64-encoded block>
{noformat}
or
{noformat}
WWW-Authenticate: NTLM
{noformat}
which is a problem because 1) it is clearly missing the required auth-param (they should have
taken realm, for instance), and 2) the parameter isn't compliant to the auth-param syntax
definition (token "=" ( token | quoted-string )).

So, to parse the string, I suggest (pseudo-code):

{noformat}
splitStrings = split(WWW-Authentication header value, ",")
foreach string in splitStrings
	; string can now either be
	; 1. a parameter for the current authentication scheme OR
	; 2. a new "auth-scheme auth-param" pair
	; 3. illegal value: "auth-scheme" without auth-param (NTLM)
	; 4. illegal value: "auth-scheme auth-param-without-name" (NTLM)

	; for case 1
	if (string matches /(TOKEN_DEF)=(VALUE_DEF)/)	; where the possibility of quoted VALUE_DEF
has to be taken into account
		assert currentAuthScheme is not null
		currentAuthScheme.parameters.add string

	; cases 2, 3, 4
	else
		s = split(string, " ")
		if s.count == 1		; case 3
			currentAuthScheme = new AuthScheme(s[0])
		elseif s.count == 2	; cases 2 and 4
			currentAuthScheme = new AuthScheme(s[0])
			currentAuthScheme.parameters.add s[1]
		else
			throw exception("unparseable www-authenticate header")
		endif
	endif
{noformat}


was (Author: bitfire):

I'm happy that I've never had to bother with NTLM authentication. According to http://www.innovation.ch/personal/ronald/ntlm.html,
the syntax is always either
{noformat}
WWW-Authenticate: NTLM <base64-encoded block>
{noformat}
which would be compliant with RFC 2616, or just
{noformat}
WWW-Authenticate: NTLM
{noformat}
which is a problem because 1) it is clearly missing the required auth-param (they should have
taken realm, for instance), and 2) the parameter isn't compliant to the auth-param syntax
definition (token "=" ( token | quoted-string )).

So, to parse the string, I suggest (pseudo-code):

{noformat}
splitStrings = split(WWW-Authentication header value, ",")
foreach string in splitStrings
	; string can now either be
	; 1. a parameter for the current authentication scheme OR
	; 2. a new "auth-scheme auth-param" pair
	; 3. illegal value: "auth-scheme" without auth-param (NTLM)
	; 4. illegal value: "auth-scheme auth-param-without-name" (NTLM)

	; for case 1
	if (string matches /(TOKEN_DEF)=(VALUE_DEF)/)	; where the possibility of quoted VALUE_DEF
has to be taken into account
		assert currentAuthScheme is not null
		currentAuthScheme.parameters.add string

	; cases 2, 3, 4
	else
		s = split(string, " ")
		if s.count == 1		; case 3
			currentAuthScheme = new AuthScheme(s[0])
		elseif s.count == 2	; cases 2 and 4
			currentAuthScheme = new AuthScheme(s[0])
			currentAuthScheme.parameters.add s[1]
		else
			throw exception("unparseable www-authenticate header")
		endif
	endif
{noformat}

> Multiple, comma-separated challenges in WWW-Authenticate are not recognized
> ---------------------------------------------------------------------------
>
>                 Key: HTTPCLIENT-1489
>                 URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1489
>             Project: HttpComponents HttpClient
>          Issue Type: Bug
>          Components: HttpClient
>    Affects Versions: 4.3.3
>            Reporter: bitfire
>              Labels: authentication, parsing
>             Fix For: 4.4 Final
>
>
> As per RFC 2616, WWW-Authenticate may contain more than one challenge:
> »User agents are advised to take special care in parsing the WWW- Authenticate field
value as it might contain more than one challenge, or if more than one WWW-Authenticate header
field is provided, the contents of a challenge itself can contain a comma-separated list of
authentication parameters.« [https://tools.ietf.org/html/rfc2616#section-14.47]
> For instance, https://contacts.icloud.com returns such a WWW-Authenticate header:
> > GET / HTTP/1.1
> > Host: contacts.icloud.com
> > Accept: */*
> > 
> < HTTP/1.1 401 Unauthorized
> < ...
> < WWW-Authenticate: X-MobileMe-AuthToken realm="Newcastle", Basic realm="Newcastle"
> The X-MobileMe-AuthToken challenge is recognized by HttpClient, but the Basic challenge
is not. HttpClient logs when sending a GET request to https://contacts.icloud.com:
> [DEBUG] headers - http-outgoing-0 << HTTP/1.1 401 Unauthorized
> [DEBUG] headers - http-outgoing-0 << Date: Fri, 21 Mar 2014 19:20:14 GMT
> [DEBUG] headers - http-outgoing-0 << X-Apple-Request-UUID: d1d0aa7d-d651-4da2-be9f-595f1619db85
> [DEBUG] headers - http-outgoing-0 << X-Responding-Instance: carddav:12100701:st13p21ic-quav11230703:8001:14B52:125783
> [DEBUG] headers - http-outgoing-0 << WWW-Authenticate: X-MobileMe-AuthToken realm="Newcastle",
Basic realm="Newcastle"
> [DEBUG] headers - http-outgoing-0 << Content-Length: 0
> [DEBUG] MainClientExec - Connection can be kept alive indefinitely
> [DEBUG] HttpAuthenticator - Authentication required
> [DEBUG] HttpAuthenticator - contacts.icloud.com:443 requested authentication
> [INFO] TargetAuthenticationStrategy - GOT Auth header: X-MobileMe-AuthToken realm="Newcastle",
Basic realm="Newcastle"
> [DEBUG] TargetAuthenticationStrategy - Authentication schemes in the order of preference:
[negotiate, Kerberos, NTLM, Digest, Basic]
> [DEBUG] TargetAuthenticationStrategy - Challenge for negotiate authentication scheme
not available
> [DEBUG] TargetAuthenticationStrategy - Challenge for Kerberos authentication scheme not
available
> [DEBUG] TargetAuthenticationStrategy - Challenge for NTLM authentication scheme not available
> [DEBUG] TargetAuthenticationStrategy - Challenge for Digest authentication scheme not
available
> [DEBUG] TargetAuthenticationStrategy - Challenge for Basic authentication scheme not
available
> The Basic auth challenge is NOT recognized!
> Reason: org.apache.http.impl.client.AuthenticationStrategyImpl:getChallenges iterates
through the WWW-Authenticate HEADERS but doesn't take account that a single header may contain
multiple challenges.
> How to fix:
> Split and parse the WWW-Authenticate header correctly in org.apache.http.impl.client.AuthenticationStrategyImpl:getChallenges




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