How does file transfer work?

[constatinus]

I request a bit of vnc protocol help, more specifycally the part i cannot find online, the ultravnc file transfer, how does it work?
Writing a client of my own.
For example, my current problem is that although i see the file transfer message structure and codes in https://github.com/ultravnc/UltraVNC/bl ... rfbproto.h line 1100, i cannot figure out why, after sending a message with 7 (the filetransfer type) as the type, 1 as the contenttype, 2 as the contentparam, 0 as the size and length and no text, expecting a drive list from the server, the server answers nothing.
This message was sent right after the vnc handshake. The server makes connection with my client after the handshake, aka the winvnc icon gets yellow.

[VNCHELP890]

Windows firewall issue?

[constatinus]

Windows firewall issue?

Well the client and server do connect to each other at first, not a firewall issue