[Pidgin] #8206: digest-md5 SASL challenges ending with a quoted value are parsed incorrectly (with cyrus-sasl disabled)

[Pidgin]

#8206: digest-md5 SASL challenges ending with a quoted value are parsed
incorrectly (with cyrus-sasl disabled)
------------------+---------------------------------------------------------
Reporter:  yann   |        Type:  defect                         
  Status:  new    |   Component:  libpurple                      
 Version:  2.5.4  |    Keywords:  sasl digest-md5 challenge quote
------------------+---------------------------------------------------------
 In the case where parse_challenge is at the last token of a challenge and
 this token has a quoted value, then it needs to rewind one character when
 cur is positioned at the terminal NULL.

 This fixes an issue where libpurple would parse a realm value (for
 instance) as 'myrealm"' instead of 'myrealm' resulting in chaos and
 failure of the SASL negotiation.

 I've seen this behaviour with Adium from subversion built with the latest
 tarball of libpurple. Applying this patch cures the problem (for libpurple
 without cyrus-sasl. It looks like stable binaries are built without, but
 cyrus-sasl is enabled in 1.4svn)

 exemple of challenge:

 algorithm=md5-sess,charset=utf-8,cipher="rc4,3des,des,rc4-56,rc4-40",maxbuf=16777215,nonce="e6439a7176aada7255ef04569a664583",qop="auth
 ,auth-conf,auth-int",realm="dev.local"

 and bogus response from libpurple:

 username="partya",realm="dev.local"",nonce="e6439a7176aada7255ef04569a664583",cnonce="3d19d459123251610177a3ccfe",nc=00000001,qop=auth
 ,digest-
 uri="xmpp/dev.local"",response=e8061ff7a5342aad60223db62b6f70e7,charset=utf-8


 Thanks,

 Yann Kerherve

-- 
Ticket URL: <http://developer.pidgin.im/ticket/8206>
Pidgin <http://pidgin.im>
Pidgin