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.
Moved the blocking state machine to the disconnect functions so that the
logout / quit functions are only responsible for sending the actual
command needed to logout or quit.
Additionally removed the hard return on failure.
Added an exception, for the STORE command, to the untagged response
processor in imap_endofresp() as servers will back respones containing
the FETCH keyword instead.
As the UID has to be specified by the user for the FETCH command to work
correctly, added a check to imap_fetch(), although strictly speaking it
is protected by the call from imap_perform().
Added imap_custom(), which initiates the custom command processing,
and an associated response handler imap_state_custom_resp(), which
handles any responses by sending them to the client as body data.
All untagged responses with the same name as the first word of the
custom request string are accepted, with the exception of SELECT and
EXAMINE which have responses that cannot be easily identified. An
extra check has been provided for them so that any untagged responses
are accepted for them.
Added imap_parse_custom_request() for parsing the CURLOPT_CUSTOMREQUEST
parameter which URL decodes the value and separates the request from
any parameters - This makes it easier to filter untagged responses
by the request command.
For consistency changed the logic of the imap_state_append_resp()
function to test for an unsucessful continuation response rather than a
succesful one.
The APPEND operation needs to be performed in several steps:
1) We send "<tag> APPEND <mailbox> <flags> {<size>}\r\n"
2) Server responds with continuation respose "+ ...\r\n"
3) We start the transfer and send <size> bytes of data
4) Only now we end the request command line by sending "\r\n"
5) Server responds with "<tag> OK ...\r\n"
This commit performs steps 4 and 5, in the DONE phase, as more
processing is required after the transfer.
Some state changes would be performed after a failure test that
performed a hard return, whilst others would be performed within a test
for success. Updated the code, for consistency, so all instances are
performed within a success test.
Not processing the final FETCH responses was not optimal, not only
because the response code would be ignored but it would also leave data
unread on the socket which would prohibit connection reuse.
A typical FETCH response can be broken down into four parts:
1) "* <uid> FETCH (<what> {<size>}\r\n", using continuation syntax
2) <size> bytes of the actual message
3) ")\r\n", finishing the untagged response
4) "<tag> OK ...", finishing the command
Part 1 is read in imap_fetch_resp(), part 2 is consumed in the PERFORM
phase by the transfer subsystem, parts 3 and 4 are currently ignored.
Added a loop to imap_statemach_act() in which Curl_pp_readresp() is
called until the cache is drained. Without this multiple responses
received in a single packet could result in a hang or delay.
RFC 3501 states that "the client MUST be prepared to accept any response
at all times" yet we assume anything received with "* " at the beginning
is the untagged response we want.
Introduced a helper function that checks whether the input looks like a
response to specified command, so that we may filter the ones we are
interested in according to the current state.
Introduced similar handling to the FETCH responses, where even the
untagged data responses are handled by the response handler of the
individual state.
Removed this pointer to a downloaded bytes counter because it was set in
imap_init() to point to the same variable the transfer functions keep
the count in (k->bytecount), effectively making the code in transfer.c
"*k->bytecountp = k->bytecount" a no-op.
From a maintenance point of view the code reads better to view tagged
responses, then untagged followed by continuation responses.
Additionally, this matches the order of responses in POP3.
Updated the FETCH command to send the UID and SECTION parsed from the
URL. By default the BODY specifier doesn't include a section, BODY[] is
now sent whereas BODY[TEXT] was previously sent. In my opinion
retrieving just the message text is rarely useful when dealing with
emails, as the headers are required for example, so that functionality
is not retained. In can however be simulated by adding SECTION=TEXT to
the URL.
Also updated test801 and test1321 due to the BODY change.
Created a new IMAP structure and changed the type of the imap proto
variable in connectdata from FTP* to the new IMAP*.
Moved the mailbox variable from the per-connection struct imap_conn to
the new per-request struct and fixed references accordingly.
Moved the clean-up of the mailbox variable from imap_disconnect() to
imap_done() as this variable is allocated in the do phase, yet would
have only been freed only once if multiple selects where preformed
on a single connection.
Daniel Stenberg