If a user indicated they preferred to authenticate using a SASL
mechanism, but SASL authentication wasn't supported by the server, curl
would always fall back to clear text when CAPABILITY wasn't supported,
even though the user didn't want to use this.
Added support for downgrading the SASL authentication mechanism when the
decoding of CRAM-MD5, DIGEST-MD5 and NTLM messages fails. This enhances
the previously added support for graceful cancellation by allowing the
client to retry a lesser SASL mechanism such as LOGIN or PLAIN, or even
APOP / clear text (in the case of POP3 and IMAP) when supported by the
server.
In preparation for the upcoming SASL downgrade feature renamed the
imap__perform_authenticate(), pop3__perform_authenticate() and
smtp__perform_authenticate() functions.
It is not 100% clear whether * should include clear text LOGIN or not
from RFC-5092, however, including it is then consistent with current
POP3 behaviour where clear text, APOP or SASL may be chosen.
If a specific SASL authentication mechanism was requested by the user
as part of the login options but wasn't supported by the server then
curl would fallback to clear text, when it shouldn't, rather than
reporting "No known authentication mechanisms supported" as the POP3
and SMTP protocols do.
Should a client application fail to decode an authentication message
received from a server, or not support any of the parameters given by
the server in the message, then the authentication phrase should be
cancelled gracefully by the client rather than simply terminating the
connection.
The authentication phrase should be cancelled by simply sending a '*'
to the server, in response to erroneous data being received, as per
RFC-3501, RFC-4954 and RFC-5034.
This patch adds the necessary state machine constants and appropriate
response handlers in order to add this functionality for the CRAM-MD5,
DIGEST-MD5 and NTLM authentication mechanisms.
Moved the standard SASL mechanism strings into curl_sasl.h rather than
hard coding the same values over and over again in the protocols that
use SASL authentication.
For more information about the mechanism strings see:
http://www.iana.org/assignments/sasl-mechanisms
The transfer size would be calculated incorrectly if the email contained
within the FETCH response, had been partially received by the pingpong
layer. As such the following, example output, would be seen if the
amount remaining was smaller than the amount received:
* Excess found in a non pipelined read: excess = 1394, size = 262,
maxdownload = 262, bytecount = 1374
* transfer closed with -1112 bytes remaining to read
Bug: http://curl.haxx.se/mail/lib-2013-08/0170.html
Reported-by: John Dunn
XOAUTH2 would be selected in preference to LOGIN and PLAIN if the IMAP
or SMTP server advertised support for it even though a user's password
was supplied but bearer token wasn't.
Modified the selection logic so that XOAUTH2 will only be selected if
the server supports it and A) The curl user/libcurl programmer has
specifically asked for XOAUTH via the ;AUTH=XOAUTH login option or 2)
The bearer token is specified. Obviously if XOAUTH is asked for via
the login option but no token is specified the user will receive a
authentication failure which makes more sense than no known
authentication mechanisms supported!
Added the ability to use an XOAUTH2 bearer token [RFC6750] with IMAP for
authentication using RFC6749 "OAuth 2.0 Authorization Framework".
The bearer token is expected to be valid for the user specified in
conn->user. If CURLOPT_XOAUTH2_BEARER is defined and the connection has
an advertised auth mechanism of "XOAUTH2", the user and access token are
formatted as a base64 encoded string and sent to the server as
"A001 AUTHENTICATE XOAUTH2 <bearer token>".
All protocol handler structs are now opaque (void *) in the
SessionHandle struct and moved in the request-specific sub-struct
'SingleRequest'. The intension is to keep the protocol specific
knowledge in their own dedicated source files [protocol].c etc.
There's some "leakage" where this policy is violated, to be addressed at
a later point in time.
1 - always allocate the struct in protocol->setup_connection. Some
protocol handlers had to get this function added.
2 - always free at the end of a request. This is also an attempt to keep
less memory in the handle after it is completed.
Removed the hard returns from imap and pop3 by using the same style for
sending the authentication string as smtp. Moved the "Other mechanisms
not supported" check in smtp to match that of imap and pop3 to provide
consistency between the three email protocols.
In addition to checking for the SASL-IR capability the user can override
the sending of the client's initial response in the AUTHENTICATION
command with the use of CURLOPT_SASL_IR should the server erroneously
not report SASL-IR when it does support it.
Fixed incorrect initial response generation for the NTLM and LOGIN SASL
authentication mechanisms when the SASL-IR was detected.
Introduced in commit: 6da7dc026c.
