find-cnetworkmessages-getisforserver

name	find-CNetworkMessages_GetIsForServer
description	Find and identify the CNetworkMessages_GetIsForServer virtual function in CS2 binary using IDA Pro MCP. Use this skill when reverse engineering CS2 networksystem.dll or libnetworksystem.so to locate the GetIsForServer vfunc by reusing the known CNetworkMessages_SetIsForServer slot and checking the adjacent CNetworkMessages vtable entry. Trigger: CNetworkMessages_GetIsForServer
disable-model-invocation	true

Find CNetworkMessages_GetIsForServer

Locate CNetworkMessages_GetIsForServer vfunc in CS2 networksystem.dll or libnetworksystem.so using IDA Pro MCP tools.

Method

1. Load CNetworkMessages_SetIsForServer from YAML

ALWAYS Use SKILL /get-func-from-yaml with func_name=CNetworkMessages_SetIsForServer.

If the skill returns an error, STOP and report to user.

Otherwise, extract:

• func_va of CNetworkMessages_SetIsForServer
• vfunc_index
• vfunc_offset

2. Load CNetworkMessages VTable from YAML

ALWAYS Use SKILL /get-vtable-from-yaml with class_name=CNetworkMessages.

If the skill returns an error, STOP and report to user.

Otherwise, extract:

• vtable_numvfunc
• vtable_entries

3. Resolve the Adjacent Getter Slot

Compute the candidate slot for CNetworkMessages_GetIsForServer:

• target_vfunc_index = CNetworkMessages_SetIsForServer.vfunc_index + 1
• target_vfunc_offset = CNetworkMessages_SetIsForServer.vfunc_offset + 8

Validate that target_vfunc_index < vtable_numvfunc, then read:

• candidate_func_addr = CNetworkMessages_vtable[target_vfunc_index]

This adjacent-slot rule is required because GetIsForServer immediately follows SetIsForServer in the CNetworkMessages vtable for networksystem.dll / libnetworksystem.so.

4. Decompile the Setter and Getter Candidate

Decompile both functions:

mcp__ida-pro-mcp__decompile addr="<CNetworkMessages_SetIsForServer_func_va>"
mcp__ida-pro-mcp__decompile addr="<candidate_func_addr>"

First, confirm CNetworkMessages_SetIsForServer is the simple byte setter pattern:

void __fastcall CNetworkMessages_SetIsForServer(__int64 a1, char a2)
{
  *(_BYTE *)(a1 + 1374) = a2;
}

Windows assembly example:

mov     [rcx+55Eh], dl
retn

Then confirm the adjacent vtable entry is the matching byte getter using the same member offset:

__int64 __fastcall sub_1800CB790(__int64 a1)
{
  return *(unsigned __int8 *)(a1 + 1374);
}

Windows assembly example:

movzx   eax, byte ptr [rcx+55Eh]
retn

The exact member offset may change across game updates. The identification rule is:

1. SetIsForServer writes one byte to this + <member_offset>
2. candidate_func_addr is the next vtable entry (index + 1)
3. The candidate reads and returns one unsigned byte from the same this + <member_offset>

If all three conditions hold, the candidate is CNetworkMessages_GetIsForServer.

5. Generate Function Signature

ALWAYS Use SKILL /generate-signature-for-function with addr=<candidate_func_addr> to generate a robust and unique func_sig for CNetworkMessages_GetIsForServer.

Use the returned validated func_sig in the next step.

6. Write IDA Analysis Output as YAML

ALWAYS Use SKILL /write-vfunc-as-yaml to write the analysis results.

Required parameters:

• func_name: CNetworkMessages_GetIsForServer
• func_addr: <candidate_func_addr>
• func_sig: The validated signature from step 5
• vfunc_sig: None

VTable parameters:

• vtable_name: CNetworkMessages
• vfunc_offset: <target_vfunc_offset> in hex
• vfunc_index: <target_vfunc_index>

Function Characteristics

• Purpose: Returns whether the CNetworkMessages instance is configured for server-side behavior
• Binary: networksystem.dll / libnetworksystem.so
• Parameters: (this) only
• Return value: An unsigned byte / boolean flag loaded from the same member written by CNetworkMessages_SetIsForServer

Discovery Strategy

1. Reuse the existing CNetworkMessages_SetIsForServer YAML to obtain the authoritative slot index
2. Reuse the existing CNetworkMessages_vtable YAML to resolve the adjacent vtable entry
3. Confirm the semantic pair:
   • setter writes this + <member_offset>
   • adjacent getter returns this + <member_offset>
4. Generate a stable func_sig from the resolved getter body

This is robust because:

• The vtable adjacency (SetIsForServer followed by GetIsForServer) is stable and explicit
• The setter/getter pair must touch the same byte member
• The final YAML stores both the resolved function signature and the precise vtable metadata

Output YAML Format

The output YAML filename depends on the platform:

• networksystem.dll -> CNetworkMessages_GetIsForServer.windows.yaml
• libnetworksystem.so -> CNetworkMessages_GetIsForServer.linux.yaml