File transfer via boost tcp - c++

Question

I want to transfer some files via tcp over lan, and so I wrote the following code for my TX-Part:
void send_data(char * filename, char * dest)
{
try
{
boost::asio::io_service io_service;
char dest_t = *dest;
std::string adr = ip_adr_display[0] + ':' + boost::lexical_cast<std::string>(PORTNUM_TCP_IN);
std::cout << "Adress is: " << adr << " and file is: " << filename << '\n';
if(debugmode)
debug_global << adr << '\n';
std::string file = filename;
async_tcp_client client(io_service, adr, file);
io_service.run();
}
catch(std::exception& e)
{
};
};
and RX-Part:
void rec_data(void)
{
try
{
std::cout << "Receiving data...\n";
async_tcp_server *recv_file_tcp_server = new async_tcp_server(PORTNUM_TCP_IN);
if(debugmode)
debug_global << "Receiving...\n";
delete recv_file_tcp_server;
}
catch(std::exception &e)
{
};
};
with the following server and client code:
using boost::asio::ip::tcp;
class async_tcp_client
{
public:
async_tcp_client(boost::asio::io_service& io_service, const std::string& server, const std::string& path):resolver_(io_service), socket_(io_service)
{
size_t pos = server.find(':');
if(pos==std::string::npos)
return;
std::string port_string = server.substr(pos+1);
std::string server_ip_or_host = server.substr(0,pos);
source_file.open(path.c_str(), std::ios_base::binary|std::ios_base::ate);
if(!source_file)
{
std::cout << "Failed to open " << path << std::endl;
return;
}
size_t file_size = source_file.tellg();
source_file.seekg(0);
std::ostream request_stream(&request_);
request_stream << path << "\n" << file_size << "\n\n";
std::cout << "Request size: " << request_.size() << std::endl;
tcp::resolver::query query(server_ip_or_host, port_string);
resolver_.async_resolve(query, boost::bind(&async_tcp_client::handle_resolve, this, boost::asio::placeholders::error, boost::asio::placeholders::iterator));
};
private:
void handle_resolve(const boost::system::error_code & err, tcp::resolver::iterator endpoint_iterator)
{
if(!err)
{
tcp::endpoint endpoint = *endpoint_iterator;
socket_.async_connect(endpoint, boost::bind(&async_tcp_client::handle_connect, this, boost::asio::placeholders::error, ++endpoint_iterator));
}
else
{
std::cout << "Error: " << err.message() << '\n';
}
};
void handle_connect(const boost::system::error_code &err, tcp::resolver::iterator endpoint_iterator)
{
if(!err)
{
boost::asio::async_write(socket_, request_, boost::bind(&async_tcp_client::handle_write_file, this, boost::asio::placeholders::error));
}
else if(endpoint_iterator != tcp::resolver::iterator())
{
socket_.close();
tcp::endpoint endpoint = *endpoint_iterator;
socket_.async_connect(endpoint, boost::bind(&async_tcp_client::handle_connect, this, boost::asio::placeholders::error, ++endpoint_iterator));
}
else
{
std::cout << "Error: " << err.message() << '\n';
};
}
void handle_write_file(const boost::system::error_code& err)
{
if(!err)
{
if(source_file.eof() == false)
{
source_file.read(buf.c_array(), (std::streamsize)buf.size());
if(source_file.gcount()<= 0)
{
std::cout << "read file error" << std::endl;
return;
};
std::cout << "Send " << source_file.gcount() << "bytes, total: " << source_file.tellg() << " bytes.\n";
boost::asio::async_write(socket_, boost::asio::buffer(buf.c_array(), source_file.gcount()),boost::bind(&async_tcp_client::handle_write_file, this, boost::asio::placeholders::error));
if(err)
{
std::cout << "Send error: " << err << std::endl;
return;
}
}
else
return;
}
else
{
std::cout << "Error: " << err.message() << "\n";
}
};
tcp::resolver resolver_;
tcp::socket socket_;
boost::array<char, 1024> buf;
boost::asio::streambuf request_;
std::ifstream source_file;
};
class async_tcp_connection: public boost::enable_shared_from_this<async_tcp_connection>
{
public:
async_tcp_connection(boost::asio::io_service& io_service):socket_(io_service), file_size(0){}
void start()
{
if(debugmode)
debug_global << __FUNCTION__ << std::endl;
async_read_until(socket_, request_buf, "\n\n", boost::bind(&async_tcp_connection::handle_read_request, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
boost::asio::ip::tcp::socket& socket(){return socket_;}
private:
boost::asio::streambuf request_buf;
size_t file_size;
std::ofstream output_file;
boost::asio::ip::tcp::socket socket_;
boost::array<char, 40960> buf;
void handle_read_request(const boost::system::error_code& err, std::size_t bytes_transferred)
{
if(err)
{
return handle_error(__FUNCTION__, err);
}
if(debugmode)
debug_global << __FUNCTION__ << "(" << bytes_transferred << ")" <<", in_avail = " << request_buf.in_avail() << ", size = " << request_buf.size() << ", max_size = " << request_buf.max_size() << ".\n";
std::istream request_stream(&request_buf);
std::string file_path;
request_stream >> file_path;
request_stream >> file_size;
request_stream.read(buf.c_array(), 2);
if(debugmode)
debug_global << file_path << " size is " << file_size << ", tellg = " << request_stream.tellg() << std::endl;
size_t pos = file_path.find_last_of('\\');
if(pos!= std::string::npos)
file_path = file_path.substr(pos+1);
output_file.open(file_path.c_str(), std::ios_base::binary);
if(!output_file)
{
if(debugmode)
debug_global << "Failed to open: " << file_path << std::endl;
return;
}
do{
request_stream.read(buf.c_array(), (std::streamsize)buf.size());
if(debugmode)
debug_global << __FUNCTION__ << " write " << request_stream.gcount() << " bytes.\n";
output_file.write(buf.c_array(), request_stream.gcount());
}while(request_stream.gcount() > 0);
async_read(socket_, boost::asio::buffer(buf.c_array(), buf.size()),boost::bind(&async_tcp_connection::handle_read_file_content, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
void handle_read_file_content(const boost::system::error_code& err, std::size_t bytes_transferred)
{
if (bytes_transferred>0)
{
output_file.write(buf.c_array(), (std::streamsize)bytes_transferred);
if(debugmode)
debug_global << __FUNCTION__ << " recv " << output_file.tellp() << " bytes."<< std::endl;
if (output_file.tellp()>=(std::streamsize)file_size)
{
return;
}
}
if (err)
{
return handle_error(__FUNCTION__, err);
}
async_read(socket_, boost::asio::buffer(buf.c_array(), buf.size()), boost::bind(&async_tcp_connection::handle_read_file_content, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
void handle_error(const std::string& function_name, const boost::system::error_code& err)
{
if(debugmode)
debug_global << __FUNCTION__ << " in " << function_name <<" due to " << err <<" " << err.message()<< std::endl;
}
};
class async_tcp_server : private boost::noncopyable
{
public:
typedef boost::shared_ptr<async_tcp_connection> ptr_async_tcp_connection;
async_tcp_server(unsigned short port):acceptor_(io_service_, boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port), true)
{
ptr_async_tcp_connection new_connection_(new async_tcp_connection(io_service_));
acceptor_.async_accept(new_connection_->socket(), boost::bind(&async_tcp_server::handle_accept, this,new_connection_, boost::asio::placeholders::error));
io_service_.run();
}
void handle_accept(ptr_async_tcp_connection current_connection, const boost::system::error_code& e)
{
if(debugmode)
debug_global << __FUNCTION__ << " " << e << ", " << e.message()<<std::endl;
if (!e)
{
current_connection->start();
//ptr_async_tcp_connection new_connection_(new async_tcp_connection(io_service_));
//acceptor_.async_accept(new_connection_->socket(),
// boost::bind(&async_tcp_server::handle_accept, this,new_connection_,
// boost::asio::placeholders::error));
}
}
~async_tcp_server()
{
io_service_.stop();
}
private:
boost::asio::io_service io_service_;
boost::asio::ip::tcp::acceptor acceptor_;
};
If I want to transmit a file, I have to enter the absolute path (why?), if I enter the relative path (e.g. "Image.jpg"), I get the error message "failed to open Image.jpg".
After successfull calling the function, I get the following output:
Adress is: <ip>:<port> and file is: <full file path>
Request size: 91
Send 1024 bytes, total: 1024 bytes
Send 1024 bytes, total: 2048 bytes
etc..
Send 1024 bytes, total: 20480 bytes
Send 406 bytes, total: -1 bytes (Why?)
At the receiving side, I get no received data. Why? I do not understand why my code is not working...
Thank you very much!

Answer 1

UPDATE In my answer I casually said
I added postfix .received to the output file name to prevent overwriting the source.
I just realized that this is likely your problem:
If you use your code with the receiver on the same machine as the sender, you will overwrite the source file while you are still sending it... OOPS.
So, I fixed up the code just I could run it.
Here's the test main:
int main()
{
boost::thread_group g;
g.create_thread(rec_data); // get the receiver running
boost::this_thread::sleep_for(boost::chrono::milliseconds(100));
g.create_thread([] { send_data("test.cpp"); });
g.join_all();
}
I added postfix .received to the output file name to prevent overwriting the source.
When running this, it appears to work reasonably well:
g++ -std=c++11 -Wall -pedantic -pthread test.cpp -lboost_system -lboost_thread
./a.out
md5sum test.cpp test.cpp.received
We get the output
0dc16e7f0dc23cb9fce100d825852621 test.cpp.received
0dc16e7f0dc23cb9fce100d825852621 test.cpp
I've also tested it with a png and with a 93Mb executable.
Full code (also on Coliru, although Coliru doesn't allow network connections):
#include <boost/asio.hpp>
#include <boost/array.hpp>
#include <boost/bind.hpp>
#include <boost/thread.hpp>
#include <iostream>
#include <fstream>
#include <boost/enable_shared_from_this.hpp>
using boost::asio::ip::tcp;
static bool debugmode = true;
static boost::mutex debug_mutex;
static std::ostream debug_global(std::clog.rdbuf());
class async_tcp_client
{
public:
async_tcp_client(boost::asio::io_service& io_service, const std::string& server, const std::string& path)
: resolver_(io_service), socket_(io_service)
{
size_t pos = server.find(':');
if(pos==std::string::npos)
{
return;
}
std::string port_string = server.substr(pos+1);
std::string server_ip_or_host = server.substr(0,pos);
source_file.open(path, std::ios_base::binary|std::ios_base::ate);
if(!source_file)
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << __LINE__ << "Failed to open " << path << std::endl;
return;
}
size_t file_size = source_file.tellg();
source_file.seekg(0);
std::ostream request_stream(&request_);
request_stream << path << "\n" << file_size << "\n\n";
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Request size: " << request_.size() << std::endl;
}
tcp::resolver::query query(server_ip_or_host, port_string);
resolver_.async_resolve(query, boost::bind(&async_tcp_client::handle_resolve, this, boost::asio::placeholders::error, boost::asio::placeholders::iterator));
};
private:
void handle_resolve(const boost::system::error_code & err, tcp::resolver::iterator endpoint_iterator)
{
if(!err)
{
tcp::endpoint endpoint = *endpoint_iterator;
socket_.async_connect(endpoint, boost::bind(&async_tcp_client::handle_connect, this, boost::asio::placeholders::error, ++endpoint_iterator));
}
else
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Error: " << err.message() << '\n';
}
};
void handle_connect(const boost::system::error_code &err, tcp::resolver::iterator endpoint_iterator)
{
if(!err)
{
boost::asio::async_write(socket_, request_, boost::bind(&async_tcp_client::handle_write_file, this, boost::asio::placeholders::error));
}
else if(endpoint_iterator != tcp::resolver::iterator())
{
socket_.close();
tcp::endpoint endpoint = *endpoint_iterator;
socket_.async_connect(endpoint, boost::bind(&async_tcp_client::handle_connect, this, boost::asio::placeholders::error, ++endpoint_iterator));
}
else
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Error: " << err.message() << '\n';
};
}
void handle_write_file(const boost::system::error_code& err)
{
if(!err)
{
if(source_file)
//if(source_file.eof() == false)
{
source_file.read(buf.c_array(), (std::streamsize)buf.size());
if(source_file.gcount()<= 0)
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "read file error" << std::endl;
return;
};
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Send " << source_file.gcount() << "bytes, total: " << source_file.tellg() << " bytes.\n";
}
boost::asio::async_write(socket_, boost::asio::buffer(buf.c_array(), source_file.gcount()),boost::bind(&async_tcp_client::handle_write_file, this, boost::asio::placeholders::error));
}
else
{
return;
}
}
else
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Error: " << err.message() << "\n";
}
};
tcp::resolver resolver_;
tcp::socket socket_;
boost::array<char, 1024> buf;
boost::asio::streambuf request_;
std::ifstream source_file;
};
class async_tcp_connection: public boost::enable_shared_from_this<async_tcp_connection>
{
public:
async_tcp_connection(boost::asio::io_service& io_service)
: socket_(io_service), file_size(0)
{
}
void start()
{
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << std::endl;
}
async_read_until(socket_, request_buf, "\n\n", boost::bind(&async_tcp_connection::handle_read_request, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
boost::asio::ip::tcp::socket& socket()
{
return socket_;
}
private:
boost::asio::streambuf request_buf;
std::ofstream output_file;
boost::asio::ip::tcp::socket socket_;
size_t file_size;
boost::array<char, 40960> buf;
void handle_read_request(const boost::system::error_code& err, std::size_t bytes_transferred)
{
if(err)
{
return handle_error(__FUNCTION__, err);
}
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << "(" << bytes_transferred << ")" <<", in_avail = " << request_buf.in_avail() << ", size = " << request_buf.size() << ", max_size = " << request_buf.max_size() << ".\n";
}
std::istream request_stream(&request_buf);
std::string file_path;
request_stream >> file_path;
request_stream >> file_size;
request_stream.read(buf.c_array(), 2);
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << file_path << " size is " << file_size << ", tellg = " << request_stream.tellg() << std::endl;
}
size_t pos = file_path.find_last_of('\\');
if(pos!= std::string::npos)
{
file_path = file_path.substr(pos+1);
}
output_file.open(file_path + ".received", std::ios_base::binary);
if(!output_file)
{
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __LINE__ << "Failed to open: " << file_path << std::endl;
}
return;
}
do
{
request_stream.read(buf.c_array(), (std::streamsize)buf.size());
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << " write " << request_stream.gcount() << " bytes.\n";
}
output_file.write(buf.c_array(), request_stream.gcount());
}
while(request_stream.gcount() > 0);
async_read(socket_, boost::asio::buffer(buf.c_array(), buf.size()),boost::bind(&async_tcp_connection::handle_read_file_content, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
void handle_read_file_content(const boost::system::error_code& err, std::size_t bytes_transferred)
{
if (bytes_transferred>0)
{
output_file.write(buf.c_array(), (std::streamsize)bytes_transferred);
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << " recv " << output_file.tellp() << " bytes."<< std::endl;
}
if (output_file.tellp()>=(std::streamsize)file_size)
{
return;
}
}
if (err)
{
return handle_error(__FUNCTION__, err);
}
async_read(socket_, boost::asio::buffer(buf.c_array(), buf.size()), boost::bind(&async_tcp_connection::handle_read_file_content, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
}
void handle_error(const std::string& function_name, const boost::system::error_code& err)
{
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << " in " << function_name <<" due to " << err <<" " << err.message()<< std::endl;
}
}
};
class async_tcp_server : private boost::noncopyable
{
public:
typedef boost::shared_ptr<async_tcp_connection> ptr_async_tcp_connection;
async_tcp_server(unsigned short port):acceptor_(io_service_, boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port), true)
{
ptr_async_tcp_connection new_connection_(new async_tcp_connection(io_service_));
acceptor_.async_accept(new_connection_->socket(), boost::bind(&async_tcp_server::handle_accept, this,new_connection_, boost::asio::placeholders::error));
io_service_.run();
}
void handle_accept(ptr_async_tcp_connection current_connection, const boost::system::error_code& e)
{
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << __FUNCTION__ << " " << e << ", " << e.message()<<std::endl;
}
if (!e)
{
current_connection->start();
}
}
~async_tcp_server()
{
io_service_.stop();
}
private:
boost::asio::io_service io_service_;
boost::asio::ip::tcp::acceptor acceptor_;
};
void send_data(std::string const& filename, std::string const& adr = "localhost:6767")
{
try
{
boost::asio::io_service io_service;
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Adress is: " << adr << " and file is: " << filename << '\n';
}
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << adr << '\n';
}
async_tcp_client client(io_service, adr, filename);
io_service.run();
}
catch(std::exception const& e)
{
std::cerr << "Exception in " << __PRETTY_FUNCTION__ << ": " << e.what() << "\n";
};
};
void rec_data(void)
{
try
{
{
boost::mutex::scoped_lock lk(debug_mutex);
std::cout << "Receiving data...\n";
}
async_tcp_server recv_file_tcp_server(6767);
if(debugmode)
{
boost::mutex::scoped_lock lk(debug_mutex);
debug_global << "Received\n";
}
}
catch(std::exception const& e)
{
std::cerr << "Exception in " << __PRETTY_FUNCTION__ << ": " << e.what() << "\n";
};
};
int main()
{
boost::thread_group g;
g.create_thread(rec_data); // get the receiver running
boost::this_thread::sleep_for(boost::chrono::milliseconds(100));
g.create_thread([] { send_data("main.cpp"); });
g.join_all();
}