CODEWITHSUNDEEP
c++socketsboost-asio
Erik
Erik

Reputation: 3208

boost sockets read_until for structs

I have successfully started using a socket in C++ , and connected to it in a python client. I started by sending just plain strings and stopping the C++ Boost whenever it encountered the delimiter (In my case I used 

// C++ boost Socket Server
std::string read_socket_command(tcp::socket & socket) {
   boost::asio::streambuf buf;
   boost::asio::read_until( socket, buf, "\n" );
   std::string data = boost::asio::buffer_cast<std::string*>(buf.data());
   return data;
}

http://think-async.com/Asio/boost_asio_1_12_1/doc/html/boost_asio/overview/core/line_based.html

my problem is, now in the Python Client I want to send over data as a struct, packed. But how do I tell the C++ code to stop reading data?

# Python Client
import struct

DATA_NAME_String = "string int int int long long int int int"
DATA_FORMAT_STRING = "25s I I I I I I I I"


def pack_data(msg):
    debug_print("Packing a message...")
    if type(msg) is SomeCustomType:
        data = ("hi", 22, 1, 4, 457, 42342, 0, 1)
    packer = struct.Struct(DATA_FORMAT_STRING)
    packed_data = packer.pack(*data)
    return packed_data

Upvotes: 1

Views: 439

Answers (1)

aep
aep

Reputation: 1675

In your packed data let the first 4 bytes(uint32_t) indicate the number of bytes of the payload. In a nutshell in sending binary data you should send the other party the size upfront. read_until is valid for a text protocol, but for binary data you probably have to use read.

Upvotes: 3

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