This is necessary because PHP in Windows does not have any certificates and some *nix systems have outdated or missing ca bundles too.
The order is:
1/ dataroot/moodleorgca.crt always wins - needs to be added manually by admin
2/ php.ini setting "curl.cainfo" is next
3/ on Windows libdir/cacert.pem is used because it does not have any default cert bundles
4/ system default is the last - the previous value, ok for properly configured *nix systems
Both classes using cURL features now access it via the core curl wrapper
class. Credit goes to Dan Poltawski for spotting the previous discrepancy
during the integration review.
There is a new hook in the index.php file. If valid HTTP parameter
installaddonrequest is detected, the installer asks the administrator to
confirm the request.
If confirmed, the installer calls download.moodle.org/api/1.2/pluginfo.php
service to get information about the given plugin version. The essential
data are the URL of the ZIP to download and the MD5 hash of the ZIP.
These data must be fetched via HTTPS to protect against MiM attack.
If the ZIP is downloaded and the MD5 content hash is correct, the user
is redirected to the previously implemented ZIP validation page, as if
the ZIP was uploaded manually.
The valid format of the installaddonrequest is documented via the
test_decode_remote_request() unit test method.
Petr Škoda