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57 lines
2.3 KiB
57 lines
2.3 KiB
15 years ago
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Sequence numbers
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================
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The idea is that whenever the user is queried for a password this
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login/pw combination gets a seq-nr. When a slave needs a login/pw
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it asks kpasswdserver and sends along the last seqnr it received. If
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this seqnr is older (lower) than the seq nr of the login/pw
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combination stored in kpasswdserver then appearantly the user has
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already been prompted for a new login/pw combination since the last
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time this slave asked for a login/pw and therefor it is not necessary
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to prompt the user again but kpassword will send the io-slave this
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new login/pw combination. If this new combination fails as well the
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user is being prompted for a new login/pw combo since the one stored
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in kpasswdserver doesn't work.
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Let me try to draw the situation I had in mind when writing this:
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Slave1 Slave2 kpasswdserver
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Asks for auth
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asks user for login/pw (1)
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sends login/pw (1) to ftp site
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Asks for auth
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sends back login/pw (1)
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sends login/pw (1) to ftp site
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gets login error,
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asks for new auth
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sends along seq.nr 1
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seq.nr 1 == (1) -->
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asks user for new login/pw (2)
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sends login/pw (2) to ftp site
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gets login error,
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asks for new auth
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sends along seq.nr 1
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seq.nr 1 < (2) -->
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don't ask user for new login/pw
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but send back login/pw (2) without asking
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sends login/pw (2) to ftp site
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Actually, I had mostly http in mind, and not so much ftp. In http you
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typically try without password first, and only when you get an
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authentication error you ask for a password. The above scenario is
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then suddenly a lot more common than with ftp because it can happen
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that you have 4 requests /io-slaves who alll discover at about the
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same time that they need to have authentication credentials. The
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above scenario (and the seq. nrs) is to prevent that you get 4 login
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dialogs in such case.
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Now the assumption in this all, looking back on it, seems to be that
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when you ask for the same auth credentials twice in a row, it must be
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that the credentials issued the first time where wrong, and you will
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be prompted again. But if the user goes to ftp-site1, then
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ftp-site2 and then back to ftp-site1 again, the credentials for ftp-site1
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are still valid. This is why we reset the seq.nr stored in the io-slave
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to 0 whenever the io-slave switches hosts (or logins).
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Waldo Bastian <bastian@kde.org>
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