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server.cpp
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server.cpp
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/******************************************************************************
* @file server.cpp
* @brief Multi client and multithreaded server with POSIX sockets for
* Linux/Unix terminal command line messenger
*
* @brief main() function is responsible for creating master socket, binding
* with specified port, listening, accepting incoming connections
* from clients and creating new socket for communication with this
* clinet. Used POSIX sockets and threads
*
* @brief client_thread() is core thread function of messenger's server,
* for each new client connection in main() is created new thread
*
* @brief client_thread() is responsible for receiving encoded message from
* client, decoding the message, determining destination client names of
* this message, private and public state of message and sending back to
* recipients of this message with appropriate way
*
* @brief message decoding and encoding is described in encode_decode.cpp and
* .hpp files
*
* @brief client_thread() also is responsible for notifying to all clients that
* this connection is online and notifying to this connection for
* available online clients. Also notifies to all about leaving the chat
*..............................................................................
* @version 2.0.0
* @author Ara Khachatryan
******************************************************************************/
#include <sys/socket.h> // Core BSD socket functions and data structures
#include <arpa/inet.h> // for manipulating IP addresses, for inet_addr()
#include <unistd.h> // for close()
#include <strings.h> // for bzero()
#include <pthread.h> // POSIX threads
#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <cerrno> // for errno
#include <cstring> // for std::strerror()
#include "encode_decode.hpp"
std::map <std::string, int> clients_list;
void * client_thread( void * );
int main(int argc, char* argv[])
{
const int port_number = 2025;
const int max_clients = 100;
int master_socket_fd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr[max_clients];
const int opt = 1;
int client_socket_fd;
pthread_t thread[max_clients];
// create socket
master_socket_fd = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
if( master_socket_fd == -1)
{
close(master_socket_fd);
std::cerr << "Cannot open tcp socket" << std::endl;
return 0;
}
// Forcefully attaching socket to the same port again after restart
if( setsockopt(master_socket_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, (const void *)&opt, (socklen_t)sizeof(opt)) == -1 )
{
std::cerr << "setsockopt" << std::endl;
return 0;
}
bzero((void *)&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = INADDR_ANY;
server_addr.sin_port = htons(port_number);
// bind socket
if( bind(master_socket_fd, (struct sockaddr *)&server_addr, (socklen_t)sizeof(server_addr)) == -1 )
{
std::cerr << "Cannot bind to port " << port_number << std::endl;
return 0;
}
if ( listen(master_socket_fd, max_clients) == -1 )
{
std::cerr << "Cannot listen" << std::endl;
return 0;
}
std::cout << "Listening socket_fd " << master_socket_fd << " on port " << port_number << "..." << std::endl;
for ( int i = 0; i < max_clients; ++i )
{
socklen_t client_addr_len = sizeof(client_addr[i]);
bzero((void *)&client_addr[i], sizeof(client_addr[i]));
// Accept incoming connections
client_socket_fd = accept(master_socket_fd, (struct sockaddr *)&client_addr[i], &client_addr_len);
if ( client_socket_fd == -1 )
{
std::cerr << "Cannot accept connection" << std::endl;
}
else
{
std::cout << "Incoming connection from: " << inet_ntoa(client_addr[i].sin_addr) << " on socket_fd: " << client_socket_fd << std::endl;
}
pthread_create( &thread[i], NULL, client_thread, (void*)&client_socket_fd );
}
return 0;
}
void * client_thread ( void * client_socket_fd )
{
char client_name[50];
bzero(client_name, sizeof(client_name));
char encoded_message[512];
std::vector<std::string> dest_names;
std::string message_info;
std::string message;
char output[512];
int fd = *(int *)client_socket_fd;
recv(fd, client_name, sizeof(client_name), 0);
// Notify to all clients that this connection is online
std::string active_clients;
size_t clinets_count = 0;
for( const auto& client: clients_list )
{
active_clients += client.first;
++clinets_count;
if ( clinets_count < clients_list.size() ) {
active_clients += ",";
}
make_encoded_message(client_name, "Server:online", std::string(" is online"), sizeof(output), output);
//print_encoded_message(output, sizeof(output));
send(client.second, output, sizeof(output), 0);
}
// Notify to this connection for available online clients
if ( !clients_list.empty() )
{
std::string is_are;
if( clinets_count > 1 )
{
is_are = std::string(" are online");
} else {
is_are = std::string(" is online");
}
make_encoded_message(active_clients.c_str(), "Server:online", is_are, sizeof(output), output);
//print_encoded_message(output, sizeof(output));
send(fd, output, sizeof(output), 0);
}
clients_list.insert(std::pair<std::string, int>(std::string(client_name), fd));
std::cout << "Thread ID: " << pthread_self() << " socket_fd: " << fd << " Name: " << client_name << std::endl;
while(1)
{
bzero(encoded_message, sizeof(encoded_message));
dest_names.clear();
message_info.clear();
message.clear();
bzero(output, sizeof(output));
int rv = recv(fd, encoded_message, sizeof(encoded_message), 0);
if ( rv == -1 )
{
std::cerr << "Error reading from client: " << std::strerror(errno) << std::endl;
break;
} else if ( rv == 0 ) {
break;
}
//print_encoded_message(encoded_message, sizeof(encoded_message));
decode_message(encoded_message, sizeof(encoded_message), dest_names, message_info, message);
// Private messages
if ( !dest_names.empty() )
{
// for each destination names in encoded_message do
for( const auto& d_name: dest_names )
{
int dest_socket_desc;
// find dest_socket_desc
std::map <std::string, int>::iterator it = clients_list.find(d_name);
if (it != clients_list.end()) {
dest_socket_desc = it->second;
} else {
std::cout << "From \"" << client_name << "\": destination name \"" << d_name << "\" not found" << std::endl;
continue;
}
std::cout << client_name << " -> " << d_name << ": " << message << std::endl;
make_encoded_message(client_name, "Private", message, sizeof(output), output);
// and send message to destination
send(dest_socket_desc, output, sizeof(output), 0);
}
// Public messages
} else {
for( const auto& client: clients_list )
{
// send message to all except sender
if ( client.first.compare(client_name) == 0 )
{
continue;
}
std::cout << client_name << " -> " << client.first << ": " << message << std::endl;
make_encoded_message(client_name, "Public", message, sizeof(output), output);
send(client.second, output, sizeof(output), 0);
}
}
}
// removing connection information from clients_list
clients_list.erase(client_name);
// Notify to all clients that this connection is leaving
for( const auto& client: clients_list )
{
make_encoded_message(client_name, "Server:online", std::string(" left the chat"), sizeof(output), output);
//print_encoded_message(output, sizeof(output));
send(client.second, output, sizeof(output), 0);
}
std::cout << "Closing connection with socket_fd: " << fd << ". Name: " << client_name
<< ". Exiting the thread." << std::endl;
close(fd);
pthread_exit(NULL);
}