CardDAV w/o PROPFIND

[axelheer]

I'm using this behind a Firewall, which seems to block PROPFIND requests.

Syncing calendars is no problem, since it uses an initial REPORT request to do its thing:

REPORT *** HTTP/1.1
User-Agent: CalDavSynchronizer/4.4
Depth: 1
Authorization: Basic ***
Content-Type: application/xml; charset=utf-8
Host: ***
Content-Length: 670
Connection: Keep-Alive

<?xml version="1.0"?>
                    <C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
                        <D:prop xmlns:D="DAV:">
                            <D:getetag/>
                        </D:prop>
                        <C:filter>
                            <C:comp-filter name="VCALENDAR">
                                <C:comp-filter name="VEVENT">
                                  <C:time-range start="20231103T000000Z" end="20250102T000000Z"/>
                                </C:comp-filter>
                            </C:comp-filter>
                        </C:filter>
                    </C:calendar-query>

But syncing contacts doesn't work:

PROPFIND *** HTTP/1.1
User-Agent: CalDavSynchronizer/4.4
Depth: 1
Authorization: Basic ***
Content-Type: application/xml; charset=utf-8
Host: ***
Content-Length: 297
Connection: Keep-Alive

<?xml version='1.0'?>
                        <D:propfind xmlns:D="DAV:">
                            <D:prop>
                              <D:getetag/>
                              <D:getcontenttype/>
                            </D:prop>
                        </D:propfind>

(returns a http 303 to some Firewall/Proxy page telling me I did something bad...)

Is it possible to configure the synchronizer in any way to avoid this kind of requests?