Proxy cannot establish connection: 'SocketProtocol' object has no attribute 'encryption'

[goekce]

Using proxy according to the example in the proxy-server docs leads to an error. The client waits in the loop afterwards.

Steps to reproduce the behavior:

1. server: xpra start
2. server: xpra proxy :20 --tcp-auth=allow --bind-tcp=0.0.0.0:14501 --daemon=no
3. client: xpra attach tcp://SERVER_ADDR:14501

• ArchLinux
• version (server & client): latest (g27b450d87)

The client logs look typical. Only problem: it waits for the session to be established.

Server logs:

2023-07-25 12:25:05,988 created tcp socket '0.0.0.0:14501'
2023-07-25 12:25:05,989 no uinput module (not usually needed)
2023-07-25 12:25:06,098 serving html content from '/usr/share/xpra/www'
2023-07-25 12:25:06,099 wrote pid 124326 to '/run/user/1000/xpra/20/server.pid'
2023-07-25 12:25:06,132 Warning: socket directory '/run/xpra'
2023-07-25 12:25:06,132  expected permissions 775 but found 777
2023-07-25 12:25:06,134 created unix domain socket '/run/user/1000/xpra/20/socket'
2023-07-25 12:25:06,154 Warning: cannot watch for application menu changes without pyinotify:
2023-07-25 12:25:06,154  No module named 'pyinotify'
2023-07-25 12:25:06,161 Warning: cannot load menu data                              
2023-07-25 12:25:06,161  No module named 'xdg'                                
2023-07-25 12:25:06,164 xpra is ready.             
2023-07-25 12:25:11,828 python-zeroconf: '::' IPv6 loopback address is not supported
2023-07-25 12:25:13,444 xpra proxy server version 5.0-r33870 (g27b450d87) beta
2023-07-25 12:25:13,468  uid=1000 (u), gid=1000 (u)
2023-07-25 12:25:13,468  running with pid 124326 on Linux Arch rolling n/a
2023-07-25 12:25:23,277 New tcp connection received                          
2023-07-25 12:25:23,277  from '10.10.10.10:52928'                                        
2023-07-25 12:25:23,277  on '0.0.0.0:14501'              
2023-07-25 12:25:23,280 Authentication required by allow authenticator module      
2023-07-25 12:25:23,281  sending challenge using 'hmac+sha512' digest over tcp connection
2023-07-25 12:25:23,418 started proxy instance pid 124387                          
2023-07-25 12:25:23,418  for client tcp socket: 10.10.20.20:14501 <- 10.10.10.10:52928
2023-07-25 12:25:23,418  and server socket socket:  <- /run/user/1000/xpra/0/socket
2023-07-25 12:25:23,420 proxy instance now also available using unix domain socket:
2023-07-25 12:25:23,420  /run/user/1000/xpra/SERVER-proxy-124387
2023-07-25 12:25:23,458 proxy video encoders: none
Process tcp socket: 10.10.20.20:14501 <- 10.10.10.10:52928:
Traceback (most recent call last):                      
  File "/usr/lib/python3.11/multiprocessing/process.py", line 314, in _bootstrap
    self.run()
  File "/usr/lib/python3.11/site-packages/xpra/server/proxy/proxy_instance_process.py", line 170, in run
    ProxyInstance.run(self)        
  File "/usr/lib/python3.11/site-packages/xpra/server/proxy/proxy_instance.py", line 128, in run
    self.send_hello()
  File "/usr/lib/python3.11/site-packages/xpra/server/proxy/proxy_instance.py", line 239, in send_hello
    hello = self.filter_client_caps(self.caps)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/xpra/server/proxy/proxy_instance.py", line 272, in filter_client_caps
    fc = self.filter_caps(caps, remove, self.server_protocol)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/xpra/server/proxy/proxy_instance.py", line 301, in filter_caps
    ncaps.update(proto_crypto_caps(proto))
                 ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/xpra/server/server_core.py", line 150, in proto_crypto_caps
    if FULL_INFO>1 or proto.encryption:
                      ^^^^^^^^^^^^^^^^
AttributeError: 'SocketProtocol' object has no attribute 'encryption'

Attaching with ssh and without proxy works fine.

[totaam]

The commit above should fix this - untested.

[goekce]

Thanks Antoine, was close enough. My patch fixes the issue.

[totaam]

@goekce the commit above is the more correct fix - unfortunately also more complicated. (also still untested)

Packets have been made immutable in v5 to prevent bugs, so the proxy needs a utility function to continue to modify packet data.

[goekce]

fixed with #3940, 1a81bb4 and 9b19cbb