find-CNetworkGameServerBase_ReplyChallenge-decompiles

Find CNetworkGameServerBase_GetChallengeType and INetworkSystem_GetSteamNetworkingSockets (Agent fallback)

Locate two virtual functions in CS2 engine2.dll / libengine2.so using IDA Pro MCP tools. This is the Agent fallback for the find-CNetworkGameServerBase_ReplyChallenge-decompiles preprocessor: it runs only when the preprocessor script returned failure. It reproduces the LLM_DECOMPILE step by hand — collecting the two virtual calls made inside the single caller CNetworkGameServerBase_ReplyChallenge:

1. CNetworkGameServerBase_GetChallengeType — dispatched on the server object (this).
2. INetworkSystem_GetSteamNetworkingSockets — dispatched on the g_pNetworkSystem global.

Both outputs are virtual dispatches (found_vcall): each YAML records the vtable slot and a vfunc_sig that pins the call instruction. There is no concrete implementation address — do not resolve or emit func_va.

Realworld Function Reference

Read the platform-relevant reference YAML before searching in IDA. It provides concrete disassembly, decompiler output, and the annotated call sites. Treat its addresses and offsets as reference-build values only; verify every result against the current binary.

• Windows: ida_preprocessor_scripts/references/engine/CNetworkGameServerBase_ReplyChallenge.windows.yaml
• Linux: ida_preprocessor_scripts/references/engine/CNetworkGameServerBase_ReplyChallenge.linux.yaml

Background — the two vcalls inside ReplyChallenge

CNetworkGameServerBase_ReplyChallenge(this, netadr, a3) builds an S2C_CHALLENGE reply packet.

• GetChallengeType is called very early — right after the bitbuf on the stack is initialized (a call of the form sub_XXXX(&buf, storage, 512, 0xFFFFFFFF)). It is a virtual call on the server object itself; its return value is the auth/challenge type, written into the bitbuf and logged as the %u auth field of "Sending S2C_CHALLENGE [%u auth %d] to %s\n", and it drives the type != 3 / type == 3 branch.