c++ - Boost asio TCP + google proto -

i first footsteps boost asio , google proto. defined small test message

message test { optional string test=1; optional int32 value=2; } 

and 1 async boost asio server response following function:

  void start()   {       test test;       test.set_test("test");       test.set_value(44444);       test.printdebugstring();      boost::asio::async_write(socket_, boost::asio::buffer(test.serializeasstring()),         boost::bind(&tcp_connection::handle_write, shared_from_this(),           boost::asio::placeholders::error,           boost::asio::placeholders::bytes_transferred));   } 

my test client is

#include <iostream> #include <boost/array.hpp> #include <boost/asio.hpp>  #include "test.pb.h"   using boost::asio::ip::tcp;  int main(int argc, char* argv[]) {   try   {     boost::asio::io_service io_service;      tcp::resolver resolver(io_service);     tcp::endpoint end_point(boost::asio::ip::address::from_string("127.0.0.1"), 15000);     tcp::socket socket(io_service);     socket.connect(end_point);     std::string data;      (;;)     {       boost::array<char, 128> buf;       boost::system::error_code error;        size_t len = socket.read_some(boost::asio::buffer(buf), error);        if (error == boost::asio::error::eof)       {          test test;          test.parsefromstring(data);          test.printdebugstring();          break; // connection closed cleanly peer.       }       else if (error)         throw boost::system::system_error(error); // other error.        data.append(buf.begin(), buf.end());      }   }   catch (std::exception& e)   {     std::cerr << e.what() << std::endl;   }    return 0; } 

if call server client few times different outputs:

test: "test" value: 44444 533 { }  test: "test" value: 44444 1644{ }  test: "test" value: 44444 

the last output expected rest wrong. dont understand why bigger output have on server :

test: "test" value: 44444 

anyone has idea why "1644{ }" ?

i think eof wrong or?

edit

message header {  required int32 size=1; } 

new start

  void start()   {       boost::asio::async_read(socket_,                 boost::asio::buffer(m_headerdata, m_sizeofheader),                 boost::bind(&tcp_connection::handle_read_header, this,                   boost::asio::placeholders::error));   } 

members:

  const size_t m_sizeofheader = sizeof(header::default_instance().serializeasstring());   boost::array<char, sizeof(header::default_instance().serializeasstring())> m_headerdata;    void handle_read_header(const boost::system::error_code& error_code) {     if (!error_code)     {         header header;         header.parsefromstring(std::string(m_headerdata.begin(), m_headerdata.end()));         header.printdebugstring();     }     else     {          std::cout << error_code.message()<< "error delete read \n";         delete this;     } 

i tried header on way now, following errors:

operation canceled or bad file descriptor

my new client sends :

  header header;   header.set_size(101);   boost::asio::write(socket,boost::asio::buffer(header.serializeasstring())) ; 

i think problem variable m_sizeofheader wrong... on server side 8, , when print output of write on client 2...

i dont understand why sizes header not fixed... have 1 required field

you ignoring number of bytes read (len) , append garbage data with:

data.append(buf.begin(), buf.end()); 

try instead:

data.append(buf.begin(), buf.begin() + len); 

also code correctly work if single message sent , socket gracefully closed (with shutdown) after that. in more complex scenario you'll need kind of protocol allows determine message bounds. instance, can send message size in first 2 bytes before message , on receiving side first read 2 bytes expected message size, read message body.