Allow custom HTTP headers in Seafile client and syncing client

Hi there, I’m a new user of Seafile. Thank you very much for building the great software! I’m filling this feature request for a scenario where the seafile server is behind a reverse proxy (like pangolin, or Cloudflare tunnel) that needs another layer of authentication.

The issue is, when seafile server runs behind the reverse proxy and the proxy requires an extra authentication, mobile client and desktop client can’t handle this and won’t be able to log in. Currently the workaround is to expose the seafile directly to the internet without proxy authentication. However, most such reverse proxies accept authentication with special HTTP headers (like token headers). If the desktop/mobile client can allow such configuration during login (and sends the headers for all the subsequent requests to the domain), the software can stay behind the proxy while functional. This solves problem for mobile/desktop client specifically.