This commit replaces that of 9f260b5d66 because according to RFC-2449,
section 6, there is no APOP capability "...even though APOP is an
optional command in [POP3]. Clients discover server support of APOP by
the presence in the greeting banner of an initial challenge enclosed in
angle brackets."
Although highlighted by a bug in commit 1cfb436a2f, APOP
authentication could be chosen if the server was to reply with an empty
or missing timestamp in the server greeting and APOP was given in the
capability list by the server.
Added a loop to pop3_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.
Similar to the processing of untagged CAPABILITY responses in IMAP and
multi-line EHLO responses in SMTP, moved the processing of multi-line
CAPA responses to pop3_state_capa_resp().
In an effort to reduce what pop3_endofresp() does and bring the POP3
source back inline with the IMAP and SMTP protocols, moved the APOP
detection into pop3_state_servergreet_resp().
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.
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
Added the ability to use an XOAUTH2 bearer token [RFC6750] with POP3 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
"AUTH 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.
Following commit e450f66a02 and the changes in the multi interface
being used internally, from 7.29.0, the transfer cancellation in
pop3_dophase_done() is no longer required.
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.
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.
Removed this pointer to a downloaded bytes counter because it was set in
pop3_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.
Updated the mailbox variable to correctly reflect it's purpose. The
name mailbox was a leftover from when IMAP and POP3 support was
initially added to curl.
Removed user and passwd from the POP3 struct as these cannot be set on
a per-request basis and are leftover from legacy FTP code.
Changed some comments still using FTP terminology.
Moved the mailbox and custom request variables from the per-connection
struct pop3_conn to the new per-request struct and fixed references
accordingly.
... since they're not used by the easy interface really, I wanted to
remove the association. Also, I unified the pingpong statemachine driver
into a single function with a 'wait' argument: Curl_pp_statemach.
A call to Curl_ssl_connect() was accidentally left in when the SSL/TLS
connection layer was reworked in 7.29. Not only would this cause the
connection to block but had the additional overhead of calling the
non-blocking connect a little bit later.
Reworked the pp->endofresp() function so that the conndata, line and
line length are passed down to it just as with Curl_client_write()
rather than each implementation of the function having to query
these values.
Additionally changed the int return type to bool as this is more
representative of the function's usage.
Corrected the order of the upgrade_tls() functions and moved the handler
upgrade and getsock() functions out from the middle of the state related
functions.
Corrected the order of the pop3_state_capa() / imap_state_capability()
and the pop3_state_capa_resp() / imap_state_capability_resp() functions
to match the execution order.
Added honoring of the tls_supported flag when starting a TLS upgrade
rather than unconditionally attempting it. If the use_ssl flag is set
to CURLUSESSL_TRY and the server doesn't support TLS upgrades then the
connection will continue to authenticate. If this flag is set to
CURLUSESSL_ALL then the connection will complete with a failure as it
did previously.
Fixed the SASL capability detection to include the space character
before the authentication mechanism list. Otherwise a capability such
as SASLSOMETHING would be interpreted as enabling SASL and potentially
trying to identify SOMETHING as a mechanism.
Tidied up code from commit 6b6bdc83bdUpdated where a few instances of
the pop3c struct variable used the longer conndata struct rather than
matching what other code in pop3_authenticate() used.
Fixed an issue where (lib)curl is compiled without support for a
supported challenge-response based SASL authentication mechanism, such
as CRAM-MD5 or NTLM, the server doesn't support the LOGIN or PLAIN
mechanisms and (lib)curl doesn't fallback to APOP or Clear Text
authentication.
Bug: http://curl.haxx.se/mail/lib-2013-02/0004.html
Reported by: Stanislav Ivochkin
pop3_state_upgrade_tls() would attempt to incorrectly complete the
upgrade to pop3s and start the CAPA command if
Curl_ssl_connect_nonblocking() returned a failure code and if ssldone
was set to TRUE. This would only happen when a non-blocking API hadn't
been provided by the SSL implementation and curlssl_connect() was
called underneath.
