Does Boost Asio networking send/recieve have any sort of data completeness guarantee?

Question

I've been using boost asio sockets (UDP and TCP) to handle a custom protocol between my client server program. Its been working great until I discovered that on TCP async_send/async_recieve calls that data can arrived in combined chunks.

For example, if I make two send calls each with it's own packet, they can arrive combined at a single receive call. I wrongly assumed that every send corresponds to a receive, but I'm obviously wrong. It however has worked well for the longest time until I found the issue running the client for a different OS.

So my question is: are there any guarantees to the completeness of the data on arrival for every receive call? (e.g. async_send 128 bytes arrive in multiples of 128 bytes, or how it arrives must always be treated as random, like 1 bytes arrives then 127 bytes is possible)

More specifically, does this mean that:

• Data can arrive concatenated or partial for every send call, and I have to always handle the concatenated/partial data manually
• Is this true for both UDP and TCP asio sockets?

I searched around and couldn't find any documentation on this so I was wondering if anyone have any idea.

Answer 1

So after some more testing here's what I concluded: the answer is no. Boost Asio sockets does not have magic that can enforce data completeness beyond what the TCP/UDP protocols enforces.

Edit: So here's more of my research:

For TCP, it acts like a data stream. So packets may arrive partial or combined and is complete. So the user application need to handle deserialization of combined or partial data.

For UDP, because it is a datagram packet, if the packet arrives, it is guaranteed to be independent and complete. So there is no need to handle partial or combined packets.