How to Reliably Deserialize a Struct from a Length-Prefixed TCP Stream?

Deserialize Struct from TCP Reception After Length Prefixing

Problem:

When deserializing a custom struct received through TCP from a separate machine, an exception is encountered: "System.Runtime.InteropServices.SafeArrayTypeMismatchException".

Original Implementation:

The struct includes serialization methods for preparing and retrieving data before and after sending. A header is added to the sent bytes to indicate the incoming data's size, in the format "l=xxxx;". The receiving end searches for this header, extracts the packet bytes, and attempts to deserialize them.

Cause of Exception:

The root cause lies in the reliance on a string for packet length determination. This approach can lead to inconsistencies when transferring data over the network.

Solution:

Implement Length-Prefixing:

Instead of using a header string, implement proper length-prefixing. This involves adding a fixed header to each "packet" sent, representing the length of the data. This length is converted to bytes, resulting in 4 bytes. The data header and the packet itself are then appended.

Packet Structure:

[Length (4 bytes)][Header (1 byte)][Data (x byte(s))]

Packet Reception and Parsing:

1. Read the first 4 bytes (Length), convert and assign them to an integer variable.
2. Read the next byte (Data Header) and store it in a variable.
3. Read x bytes into a byte array, where x is the integer from step 1.
4. Use the Data Header from step 2 to determine what to do with the data.

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