- Detach and disconnect an attached connection before performing.
Prior to this change it was not possible to safely reuse an easy handle
with an attached connection in a second call to curl_easy_perform. The
only known case of this is a connect-only type handle where the
connection was detached when curl_easy_perform returned, only to be
reattached by either curl_easy_send/recv.
This commit effectively reverts 2f8ecd5d and be82a360, the latter of
which treated the reuse as an error. Prior to that change undefined
behavior may occur in such a case.
Bug: https://curl.se/mail/lib-2025-01/0044.html
Reported-by: Aleksander Mazur
Closes https://github.com/curl/curl/pull/16008
This typically happens if CURL_CONNECT_ONLY is used and a second
curl_easy_perform() is attempted.
A connection "taken over" with CURL_CONNECT_ONLY cannot be ended any
other way than a curl_easy_cleanup() on the easy handle that holds it.
Add test 696 to verify.
Closes#16003
