# Find LegacyGameEventListener

> Locate LegacyGameEventListener in CS2 server.dll or server.so using IDA Pro MCP tools.

- Skill: `tools-only/find-legacygameeventlistener` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/find-legacygameeventlistener`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/find-legacygameeventlistener/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-29
- Page: https://skillmd.com/skills/tools-only/find-legacygameeventlistener

---


# Find LegacyGameEventListener

Locate `LegacyGameEventListener` in CS2 server.dll or server.so using IDA Pro MCP tools.

## Method

1. Search for the debug string:
   ```
   mcp__ida-pro-mcp__find_regex pattern="CSource2GameClients::StartHLTVServer: game event %s not found"
   ```

2. Get cross-references to the string:
   ```
   mcp__ida-pro-mcp__xrefs_to addrs="<string_addr>"
   ```

3. Decompile the referencing function:
   ```
   mcp__ida-pro-mcp__decompile addr="<function_addr>"
   ```

4. Identify the LegacyGameEventListener function:
   - Look for a function call that takes a single integer parameter (a2) and returns a pointer
   - The pattern looks like:
     ```c
     v5 = sub_XXXXXX(a2);  // This is LegacyGameEventListener
     v6 = (*(__int64 (__fastcall **)(__int64))(*(_QWORD *)v4 + 80LL))(v4);
     v7 = *(const char **)v6;
     if ( *(_QWORD *)v6 )
     {
       do
       {
         v8 = sub_YYYYYYYY(off_ZZZZZZZ, v7, 0LL);
         if ( v8 )
           sub_WWWWWWWW(off_ZZZZZZZ, v5, v8, 2LL);
         else
           DevMsg("CSource2GameClients::StartHLTVServer: game event %s not found.\n", v7);
     ```
   - The function `sub_XXXXXX` called with parameter `a2` is `LegacyGameEventListener`

5. Rename the function:
   ```
   mcp__ida-pro-mcp__rename batch={"func": [{"addr": "<function_addr>", "name": "LegacyGameEventListener"}]}
   ```

6. Generate and validate unique signature:

   **ALWAYS** Use SKILL `/generate-signature-for-function` to generate a robust and unique signature for the function.

7. Write IDA analysis output as YAML beside the binary:

   **ALWAYS** Use SKILL `/write-func-as-yaml` to write the analysis results.

   Required parameters:
   - `func_name`: `LegacyGameEventListener`
   - `func_addr`: The function address from step 4
   - `func_sig`: The validated signature from step 6

## String References

The function is identified by finding code that:
- Calls `LegacyGameEventListener` with an integer parameter
- Then iterates through game events, calling functions with the result
- Uses `DevMsg` to log when a game event is not found

## Function Characteristics

- **Parameters**:
  - `arg0`: Integer (unsigned int) - event listener index

- **Return Value**: Pointer to game event listener structure or 0 if invalid

- **Purpose**: Retrieves a legacy game event listener by index from a global array

## Code Pattern Details

The function performs bounds checking:
1. Checks if a global pointer is valid
2. Validates that the index is <= 0x3F (63)
3. Calculates the address: `base + (index + 4) * 16`
4. Returns the calculated address or 0 if validation fails

## Output YAML Format

The output YAML filename depends on the platform:
- `server.dll` → `LegacyGameEventListener.windows.yaml`
- `server.so` → `LegacyGameEventListener.linux.yaml`

```yaml
func_va: 0x180b0eb70   # Virtual address of the function - This can change when game updates.
func_rva: 0xb0eb70     # Relative virtual address (VA - image base) - This can change when game updates.
func_size: 0x23        # Function size in bytes - This can change when game updates.
func_sig: XX XX XX XX XX  # Unique byte signature for pattern scanning - This can change when game updates.
```