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.
