Fix Stack Out-of-Bounds Read Issue in ForwardOpen Parsing

[MrAlaskan]

Summary

This change fixes an out-of-bounds read in the Forward Open request path by rejecting undersized requests before they reach ConnectionObjectInitializeFromMessage().

Vulnerability Description

A Forward Open or Large Forward Open request can reach the connection object parser without a minimum input length check. A short request may therefore trigger out-of-bounds reads while multiple fixed fields are decoded from the incoming buffer (see #564).

Fix Logic

This fix keeps the change small and localized to source/src/cip/cipconnectionmanager.c.

The fix works as follows:

1. Preserve whether the current request is Forward Open or Large Forward Open
2. Reinitialize g_dummy_connection_object to a known empty state before parsing
3. Enforce a minimum request payload length before calling ConnectionObjectInitializeFromMessage()
4. Reject undersized requests with kCipErrorNotEnoughData

The minimum lengths used are:

• 35 bytes for Forward Open
• 39 bytes for Large Forward Open

After this fix, short requests are rejected at the entry point and no longer reach the unbounded field reads in the connection object initializer.