Fix segfault in large packets

[GorComComputing]

The segfault occurs due to a signed integer overflow (it becomes negative).
The integer overflow happens when the size of a received PostgreSQL protocol packet exceeds 0x80000000 (2 GB).

In the PostgreSQL wire protocol, the packet size is specified as a 4-byte integer, which theoretically allows sending packets up to 4 GB in size.
However, in practice, the Postgres server allocates memory blocks of up to 1 GB:

#define MaxAllocSize    ((Size) 0x3fffffff)

When receiving a packet, the server checks its length value, and if it exceeds 1 GB (0x3fffffff), it stops processing the packet and returns an error:

invalid message length

Therefore, to fix the segfault, it was decided to add a handler that ensures the packet size does not exceed 0x80000000 (2 GB).