feat(server): add ConnectionHandler trait for connection lifecycle hooks

[Greg Lamberson (glamberson)]

Summary

Add optional ConnectionHandler to RdpServer::run() with two lifecycle callbacks:

• on_accept(peer) -> bool: called after accept(), return false to reject the connection before run_connection()
• on_disconnected(peer, duration, error) -> PostConnectionAction: called after run_connection() completes, return Stop to exit the accept loop

This enables server implementations to add:

• Pre-accept filtering (rate limiting, IP allowlists)
• Post-disconnect cleanup (session validity checks, metrics collection)
• Controlled shutdown when external state becomes invalid (e.g. compositor session terminated)

Both methods have default implementations that accept all connections and continue unconditionally, so existing callers are unaffected.

Motivation

lamco-rdp-server currently duplicates the entire run() accept loop (~100 lines) to add connection lifecycle hooks for D-Bus event emission, PAM peer IP tracking, and Portal session validity checks. With ConnectionHandler, it can adopt the upstream run() directly.

The key gap was PostConnectionAction::Stop: after each client disconnects, lamco checks whether the Wayland compositor session is still valid and stops accepting if not. The existing ServerEvent::Quit mechanism requires the handler to know about IronRDP internals; PostConnectionAction keeps the contract explicit.

Changes

• server.rs: ConnectionHandler trait, PostConnectionAction enum, connection_handler field on RdpServer, hooks wired into run() accept loop
• builder.rs: with_connection_handler() on BuilderDone, ConnectionHandler import, BuilderDone field

Test plan

• Existing tests pass (all 5 xtask gates green)
• Server without handler: behavior unchanged (default impls)
• Server with handler returning Stop: accept loop exits after disconnect
• Server with handler rejecting on_accept: connection dropped, loop continues

[Copilot]

Pull request overview

This PR introduces a configurable connection lifecycle hook mechanism for ironrdp-server by adding an optional ConnectionHandler to RdpServer::run(), enabling pre-accept filtering and post-disconnect actions (including controlled shutdown of the accept loop).

Changes:

• Added ConnectionHandler trait with default on_accept / on_disconnected lifecycle callbacks and PostConnectionAction for post-disconnect control flow.
• Wired the handler into the RdpServer::run() accept loop (reject-before-run and stop-after-disconnect behaviors).
• Extended the server builder with with_connection_handler() and plumbed the handler into RdpServer::new().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
crates/ironrdp-server/src/server.rs	Defines ConnectionHandler / PostConnectionAction and integrates callbacks into the accept loop.
crates/ironrdp-server/src/builder.rs	Adds builder plumbing to configure and pass a ConnectionHandler into RdpServer.

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[Benoît Cortier (CBenoit)]

Perfect! Thank you!