Design/FileServer

Design ideas for a slim non blocking file server

• The socket to the client is in non blocking mode.
  • IO only happens via tevent_req based functions.

• Each connection is represented by a structure.
  • Everything that belongs to the connection is a talloc child of this structure.
  • The connection has one tevent_context to operate on.
  • No global variables.
  • exit() is not used, but a ..._disconnect() function which gets the connection structure passed.
  • All structures and functions should have nice names with a unique prefix (something like smbsrv_*).

• Authentication is done via a wbclient library (or something similar) only.
  • The library should be tevent_req based.
  • The library should also be used for krb5.

• The file server handles SMB1 and SMB2.
  • The marshalling is strictly separated from the logic.
  • But sendfile/recvfile/splice must still be possible.
  • The file server shouldn't know anything about unix users/uids.

• The file server talks to a protocol independent ntvfs layer.
  • To keep it simple only one module is allowed per tree connect (maybe extended to a module chain later).
  • All functions are tevent_req based.
  • All structures and functions should have nice names with a unique prefix (something like ntvfs_*).
  • All structures and functions within a backend should have the same prefix.

• The IPC backend operates only async:
  • Named pipes are supported genericly via unix sockets. (see lib/named_pipe_auth/)
  • The LANMAN pipe for RAP also talks to a different process via an unix socket.
  • We need to think a bit more about how to handle DFS requests.

• The PRINT backend operates only async:
  • It uses a local directory to store files.
  • It prints the localy stored files via ncalrpc to the local spoolss server.

• The FILE backend operates only async:
  • It uses the tevent_req based thread trick to make system calls non blocking.
  • We could use a tevent_req based wrapper to the Portable Coroutine Library to make complex functions fully async (we need to experiment a bit first).
  • Filesystem specific features can be implemented by a posix vfs layer (Maybe the existing Samba3 VFS layer, but maybe much simpler)
  • The async wbclient library is used to translate uids/gids to sids.