Fix member function call on null-pointer instance of SignalingClient

[pjungkamp]

Bug

libwebsockets calls the protocol callbacks for our webrtc signaling client even when the connection is not explicitly initiated from the signaling client code. This causes the protocolCallbackStatic function to cast a null-pointer to a SignalingClient and call the non-static protocolCallback.

Fix

I moved the entire protocolCallback logic into the static member function and removed the non-static member function.

Context

I found this bug using -fsanitize=address and -fsanitize=undefined. This bug occurs on an idle villas-node process, without any configuration or user input.

$ ./build/src/villas-node
11:10:04 info node             This is VILLASnode v0.11.0-db2bd63-debug (built on Jan  1 1980, 00:00:00)
11:10:04 info signals          Initialize subsystem
11:10:04 warn node             No configuration file specified. Starting unconfigured. Use the API to configure this instance.
11:10:04 info memory           Initialize memory sub-system: #hugepages=100
11:10:04 warn memory:mmap      Running in an unprivileged environment. Hugepages are not used!
11:10:04 warn memory           Running in an unprivileged environment. Memory is not locked to RAM!
11:10:04 info kernel:rt        Initialize sub-system
11:10:04 warn kernel:rt        We recommend to use an PREEMPT_RT patched kernel!
11:10:04 warn kernel:rt        You might want to use the 'priority' setting to increase VILLASnode's process priority
11:10:04 warn kernel:rt        You might want to use the 'affinity' setting to pin VILLASnode to dedicate CPU cores
11:10:04 info api              Starting sub-system
11:10:04 info web              Starting sub-system
11:10:04 info api              Started worker
11:10:05 info web              Started worker
11:10:05 info stats             Node      │      Recv │      Sent │      Drop │      Skip │  OWD last │  OWD mean │ Rate last │ Rate mean │  Age mean │   Age Max │ Signals
11:10:05 info stats                       │      pkts │      pkts │      pkts │      pkts │      secs │      secs │   pkt/sec │   pkt/sec │      secs │       sec │ signals
11:10:05 info stats            ───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼───────────┼─────────
/home/pjungkamp/Projects/VILLASframework/node/lib/nodes/webrtc/signaling_client.cpp:107:29: runtime error: member call on null pointer of type 'struct SignalingClient'
^C11:10:35 info node             Received Interrupt signal. Terminating...
11:10:35 info api              Stopping sub-system
11:10:35 info api              Stopped worker
11:10:35 info web              Stopping sub-system
11:10:35 info web              Stopped worker
11:10:35 info node             Goodbye!

[Copilot]

Pull Request Overview

This PR refactors the WebRTC signaling client’s protocol callback to eliminate a crash when the callback is invoked on a null instance. It inlines the former non-static protocolCallback into the static entry point and updates registration in lib/web.cpp.

• Switch .callback in lib/web.cpp to the unified static protocolCallback
• Merge logic into the static callback and remove the old non-static overload
• Adjust internal calls to use the session user pointer (c->…)
• Add gdb to development tools in flake.nix

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
lib/web.cpp	Updated protocol registration to use the new static callback
lib/nodes/webrtc/signaling_client.cpp	Inlined non-static logic into protocolCallback, removed old overload, fixed dummy callback invocation
include/villas/nodes/webrtc/signaling_client.hpp	Removed obsolete member declaration, updated static callback signature
flake.nix	Added gdb to development dependencies