IMAP: FETCH command only returns first line of each message response

[bohwaz]

I did this

curl imaps://imap.example.org:993/INBOX -X 'UID FETCH 1 (BODY.PEEK[TEXT])' -u user:password

I expected the following

I should have received this:

* 1 FETCH (UID 1 BODY[TEXT] {447}
(... 447 bytes of message body ...)
)

(note the final closing parenthesis on the last line)

This is what can be seen by adding -v to the curl command.

But instead curl only returns the first line:

* 1 FETCH (UID 1 BODY[TEXT] {447}

This means that using libcurl with a programming language, I cannot parse the received response for FETCH if it includes any BODY query, eg. BODY.PEEK[HEADER.FIELDS (X-Mailer)] will fail as well.

Of course I can still use the shortcut provided by curl (curl 'imaps://imap.example.org:993/INBOX/;UID=1'), but then it's not the same as doing a FETCH with only the information I need for multiple messages.

curl/libcurl version

8.16.0

operating system

Debian Linux Trixie

[tiymat]

I took a look at this, it seems all IMAP custom commands (ones set via -X rather than letting curl build them up itself) get sent via imap_perform_list, so their responses are handled by imap_state_listsearch_resp.

There is logic to parse out the download size from the IMAP response and call Curl_xfer_setup_recv to get the content in imap_state_fetch_resp, but imap_state_listsearch_resp just writes the IMAP response line itself, and doesn't call Curl_xfer_setup_recv to get the body.

One (potentially hacky) solution could be to add the download logic in the fetch response handler to the list/search response handler, possibly by breaking that logic out into a separate method and calling it from both response handlers.

The other approach I can think of would be to update imap_perform_fetch to also be able to handle custom commands, rather than shoehorning them all through the list logic.

[thebitbrine]

Found and fixed the issue. The problem was that custom commands route through imap_state_listsearch_resp() which didn't detect IMAP literal syntax {size}.

Added literal detection to that handler. It now parses the {size} marker, writes the header line, handles any buffered data, and sets up the transfer layer to read the literal body. Also updated imap_done() to transition custom FETCH commands to FETCH_FINAL state.

Tested with the full IMAP test suite: no regressions. Your use case should work now:

curl imaps://imap.example.org:993/INBOX -X 'UID FETCH 1 (BODY.PEEK[TEXT])' -u user:password

Now it will return the full response including the literal body and closing parenthesis.