boost::asio async_read guarantee all bytes are read

Question

I have a server that receives a compressed string (compressed with zlib) from a client, and I was using async_receive from the boost::asio library

Answer 1

Use async_read_until and create your own match condition, or change your protocol to send a header including the number of bytes to expect in the compressed string.

Answer 2

How were you expecting to do this using any other method?

There are a few general methods to sending data of variable sizes in an async manor:

1. By message - meaning that you have a header that defines the length of the expected message followed by a body which contains data of the specified length.
2. By stream - meaning that you have some marker (and this is very broad) method of knowing when you've gotten a complete packet.
3. By connection - each complete packet of data is sent in a single connection which is closed once the data is complete.

So can your data be parsed, or a length sent etc...

Answer 3

A single IP packet is limited to an MTU size of ~1500 bytes, and yet still you can download gigabyte-large files from your favourite website, and watch megabyte-sized videos on YouTube.

You need to send a header indicating the actual size of the raw data, and then receive the data by pieces on smaller chunks until you finish receiving all the bytes.

For example, when you download a large file over HTTP, there is a field on the header indicating the size of the file: Content-Length:.