I'm working on a server/client chat room for school.
Everything worked fine until I decided to get inputs of my Clients. Since then, I don't know why but every time I create a new socket, it will always be the same. I've tried to create a new solution, and just create a socket and even their.. sockets are the same.
My test code as simple as that:
#pragma comment (lib, "Ws2_32.lib")
#include <WinSock2.h>
#include <iostream>
int main()
{
WSADATA wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData))
{
return 1;
}
// Create Socket
SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);
char a;
std::cout << "Socket : " << sock << std::endl;
std::cin >> a;
}
I end up with 4 times the same socket is created:
Some time, weirdly it works completely fine, but shortly after it gets back to that.
Edit:
To talk more about the project, I'm not sure how to explain the code without sending 300 lines which I assume isn't the best idea.
So here is my update for the server (yes we're using Polls cause my teacher don't want us to use multithreading for now).
void Server::Update()
{
do
{
WSAPoll(fds_, MAX_CLIENTS, -1);
for (int i = 0; i < MAX_CLIENTS; ++i)
{
if (fds_[i].revents & POLLRDNORM)
{
if (i == 0)
{
// Accept
AcceptClient(sock_);
}
else
{
// Receive
ReceiveMsg(fds_[i].fd, receiveBuffer);
// Send the message to all clients except the sender
for (int j = 0; j < clients_.size(); ++j)
{
if (clients_[j].socket != fds_[i].fd)
{
SendMsg(clients_[j].socket, receiveBuffer);
}
}
}
}
if (fds_[i].revents & POLLHUP)
{
closesocket(clients_[i].socket);
std::cout << "Client with socket " << clients_[i].socket << " disconnected" << std::endl;
clients_.erase(clients_.begin() + i);
}
}
} while (true);
}
Here is the Accept code:
void Server::AcceptClient(SOCKET sock)
{
// Client Socket
SOCKET csock;
SOCKADDR_IN csin;
int crecsize = sizeof(csin);
// Address Buffer
char adressBuffer[65];
csock = accept(sock, (SOCKADDR*)&csin, &crecsize);
if (csock != INVALID_SOCKET)
{
std::cout
<< "Client with socket " << csock
<< " connected from " << inet_ntop(AF_INET, &csin.sin_addr, adressBuffer, sizeof(adressBuffer))
<< ":" << csin.sin_port << std::endl;
clients_.push_back(Client(csock));
fds_[clients_.size()].fd = csock;
fds_[clients_.size()].events = POLLIN;
}
else
{
printError(WSAGetLastError(), __LINE__, __FILE__);
return;
}
}
But, by using WSAGetLastError() I know that the error occur client side during the call of connect():
void NetworkClient::ConnectToServer(SOCKET sock, SOCKADDR_IN sin, int recsize)
{
int sock_err = connect(sock, (SOCKADDR*)&sin, recsize);
if (sock_err != INVALID_SOCKET)
{
std::cout << "Connexion avec le serveur reussie" << std::endl;
}
else
{
printError(WSAGetLastError(), __LINE__, __FILE__);
return;
}
}
So I still end up with the same error, even though my socket is non-blocking.
Unlike on other platforms, where sockets are indexes into a per-process file table, sockets on Windows are kernel objects. When a process exits, any open objects are released automatically, allowing the kernel to reuse them. This is perfectly normal behavior.
UPDATE:
But, by using WSAGetLastError() I know that the error occur client side during the call of connect()
The error code you have shown is 10035 (WSAEWOULDBLOCK), which is normal behavior for a non-blocking connect(). It is NOT an error condition, so don't treat it like one. It simply means the connection operation is in progress. WSAPoll() (or select(), etc) will tell you at a later time when the operation is actually finished, and whether it was successful or not (in your case, the connection is successful, as evident by your server log). This is explained in the connect() documentation:
For connection-oriented, nonblocking sockets, it is often not possible to complete the connection immediately. In such a case, this function returns the error WSAEWOULDBLOCK. However, the operation proceeds.
When the success or failure outcome becomes known, it may be reported in one of two ways, depending on how the client registers for notification.
If the client uses the select function, success is reported in the writefds set and failure is reported in the exceptfds set.
If the client uses the functions WSAAsyncSelect or WSAEventSelect, the notification is announced with FD_CONNECT and the error code associated with the FD_CONNECT indicates either success or a specific reason for failure.
Related
I am trying to find a way to close a server safely while it is listening for incoming client connection without using the classic ctrl+C in linux. I would like to terminate the program for example by keyboard input of Q or -quit etc... and do so instantly after pressing enter, not after accepting, for example, a client connection. How should I implement this?
Here is my sample code.
int startSocketConnection() {
socketFD = socket(AF_INET, SOCK_STREAM, 0);
//TODO exceptions
if (socketFD < 0) {
std::cout << "\nError establishing socket...\nexiting..." << std::endl;
return (-1);
}
std::cout << "\nSocket server has been created..." << std::endl;
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htons(INADDR_ANY);
server_addr.sin_port = htons(portNum);
//TODO exceptions
if ( (bind(socketFD, (struct sockaddr*) &server_addr, sizeof(server_addr))) < 0 ) {
std::cout << "Error binding connection, Socket has already been established" << std::endl;
return (-1);
}
std::cout << "Listening for incoming client connection..." << std::endl;
listen(socketFD, 1);
size = sizeof(client_addr);
while (sessionActive) {
newSocketFD = accept(socketFD, (struct sockaddr *) &client_addr, &size);
if (newSocketFD < 0) error("ERROR on accept");
//fork() returns child pid to parent, 0 to the child process.
pid = fork();
if (pid < 0) error("ERROR on fork");
//if child process...
if (pid == 0) {
close(socketFD);
//process client query...
sessionActive = dostuff(newSocketFD);
signal(SIGCHLD, SIG_IGN);
std::cout << "Child process terminated!" << std::endl;
exit(0);
}
else {
close(newSocketFD);
}
}
close(socketFD);
return 0;
}
You need to either add another thread that reads from stdin and unceremoniously exits your application when it sees those commands, or change your code to use a command like select or poll to see which descriptors have input available: add the descriptor for stdin (for your purposes, you can trust it to be 0) alongside the descriptor for the listening socket, and when either or both have input events your select or poll will return and - if it tells you stdin has data - you can read from it without blocking: if you see your termination command, exit.
For select/poll, you should set the socket you're calling accept on to non-blocking, as it's possible to be notified of an incoming connection attempt but by the time you go to accept that connection may have already failed - you don't want accept to block and stop your select or poll call monitoring stdin too for you.
Of the two, the extra thread is easiest - here's a minimal program illustrating how to start it and have it monitor stdin while your main thread's doing its own stuff. On Linux, link with -lpthread.
#include <thread>
#include <iostream>
#include <string>
#include <unistd.h> // for sleep
int main()
{
std::thread t{
[] {
std::string s;
while (std::cin >> s)
if (s == "exit")
{
std::cout << "exit command given on stdin\n";
exit(0);
}
}
};
t.detach();
while (true)
{
sleep(2);
std::cout << "beat\n";
}
}
(It does get a bit more complicated if you want "orderly" shutdown, where destructors for objects in the main thread are guaranteed to run....)
I read about select() and also read many examples of it, but I can't understand when can I use it?
I understood that I can use it in the accept() function, in case I want few people to connect to the server, but it has confused me.
I need to built a server that receive data only from 2 clients, 1 every time. The first user sends to the server a string, the string responds and then the second user sends a string.
Can someone help me with combining the select() function in the recv() function?
I've added my server.cpp code. Thank you!
server:
#include <iostream>
#include <winsock2.h>
#include <string>
#include <windows.h>
#include <vector>
#pragma comment(lib,"ws2_32.lib")
#define MAX_NUMBER_OF_PLAYERS 1
#define BUFFER_SIZE 1024
#define LIMIT 1
// server side
#define INVALID_MOVE 00
#define PLEASE_ENTER_A_MOVE 15
#define PRINT_BOARD 20
#define END_GAME 30
// client side
#define MOVE 10
using namespace std;
int main()
{
WSADATA WsaDat;
SOCKET clientsock[2];
int minsock = 0;
int numsocks = MAX_NUMBER_OF_PLAYERS;
if (WSAStartup(MAKEWORD(2, 2), &WsaDat) != 0)
{
std::cout << "WSA Initialization failed!\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
SOCKET serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (serverSocket == INVALID_SOCKET)
{
std::cout << "Socket creation failed.\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
SOCKADDR_IN serverInf;
serverInf.sin_family = AF_INET;
serverInf.sin_addr.s_addr = INADDR_ANY;
serverInf.sin_port = htons(8888);
if (bind(serverSocket, (SOCKADDR*)(&serverInf), sizeof(serverInf)) == SOCKET_ERROR)
{
std::cout << "Unable to bind socket!\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
listen(serverSocket, 5);
clientsock[0] = accept(serverSocket, NULL, NULL);
cout << "Client 1 has connected." << endl;
clientsock[1] = accept(serverSocket, NULL, NULL);
cout << "Client 2 has connected." << endl;
for (int i = 0; i < 2; i++)
{
cout << "Client " << i+1 << " Has Connected!" << endl;
}
char client1_buffer[BUFFER_SIZE];
char client2_buffer[BUFFER_SIZE];
char* clientBuffer;
// until there isn't a mate.
bool gameRunning = true;
// user represents if it's user1 (0), or user2(1)
bool user = 0;
while (gameRunning)
{
if (!user)
clientBuffer = client1_buffer;
else
clientBuffer = client2_buffer;
int in = recv(clientsock[user], clientBuffer, BUFFER_SIZE, 0);
cout << in << endl;
if (in > 0)
{
// CHECKS
// MOVE COMMAND
// IF worked, send the board to both clients. if current user = 1 ==> do user to 0 | if the user = 0 => do user to 11
// ELSE, send the current client (clientsock[user]) Error message and ask for a command again.
cout << clientBuffer << endl;
cout << " IN RECV";
char* szMessage = "15";
send(clientsock[user], szMessage, sizeof(szMessage), 0);
}
else if (in == 0)
{
// The connection has closed.
// REMEMBER : SAVE THE GAME SITUATION.
}
else
{
printf("recv failed: %d\n", WSAGetLastError());
// SEND ERROR MESSAGE TO BOTH CLIENTS
}
user = !user;
}
// Shutdown our socket
shutdown(serverSocket, SD_SEND);
// Close our socket entirely
closesocket(serverSocket);
WSACleanup();
system("pause");
return 0;
}
Ok, now that you corrected your code, I have to do some work.
I suggest you remove this
user = !user
and add this immediately after the beginning of the while loop:
{
int nfds = 0; // smallest number higher than all socket descriptors
fd_set set; // this contains garbage from the stack, thus ...
FD_ZERO(&set); // first clean it and then add both client sockets:
FD_SET(clientsock[0],&set); if(nfds<=clientsock[0]) nfds=clientsock[0]+1;
FD_SET(clientsock[1],&set); if(nfds<=clientsock[1]) nfds=clientsock[1]+1;
select(nfds,&set,0,0,0); // this uses and changes the content of set
bool next = !user; // next is the other user, and we try to serve it:
if(FD_ISSET(clientsock[next],&set)) user=next;
}
By the way, I like your creative way of using bool as an index, though once you have more than 2 clients, you might have to change that concept.
My code implements a little bit of scheduling policy: If there is data available from both clients, it reads from that client from which it did not read data the previous time. If, instead, you want to read lots of data from one client and then lots of data from the other, replace the lines containing next by
if(!FD_ISSET(clientsock[user],&set)) user=!user;
The first version tries to alternate as often as possible, while the second tries to read as much data as possible from the same client before switching to the other.
I am programming a real-time game in which I need reliable UDP, so I've chosen to work with UDT (UDP-based data transfer protocol - http://sourceforge.net/projects/udt/).
The clients (on browsers) send real-time messages to my server via CGI scripts. The problem is that there are some messages that are being lost, and I don't know why because the server says that it sent all the messages successfully to the corresponding clients, but sometimes the client doesn't receive the message.
In my debug file, I've found that when a message is not received by the client, its script says:
error in recv();
recv: Connection was broken.
I would like to get some help on how the server shall know if the client got its message; should I send a NACK or something from the client side? I thought that UDT should do that for me. Can someone clarify this situation?
The relevant sections of the communication parts of my code are bellow, with some comments:
server's relevant code:
//...
void send_msg_in(player cur, char* xml){
/*this function stores the current message, xml, in a queue if xml!=NULL, and sends the 1st message of the queue to the client*/
/*this function is called when the player connects with the entering xml=NULL to get the 1st message of the queue,
or with xml!=NULL when a new message arrives: in this case the message is stored in the queue, and then the message will be sent in the appropriate time, i.e. the messages are ordered.*/
char* msg_ptr=NULL;
if (xml!=NULL){ //add the message to a queue (FIFO), the cur.xml_msgs
msg_ptr=(char*) calloc(strlen(xml)+1, sizeof(char));
strcpy(msg_ptr, xml);
(*(cur.xml_msgs)).push(msg_ptr);
} //get the 1st message of the queue
if (!(*(cur.xml_msgs)).empty()){
xml=(*(cur.xml_msgs)).front();
}
if (cur.get_udt_socket_in()!=NULL){
UDTSOCKET cur_udt = *(cur.get_udt_socket_in());
// cout << "send_msg_in(), cur_udt: " << cur_udt << endl;
//send the "xml", i.e. the 1st message of the queue...
if (UDT::ERROR == UDT::send(cur_udt, xml, strlen(xml)+1, 0)){
UDT::close(cur_udt);
cur.set_udt_socket_in(NULL);
}
else{ //if no error this else is reached
cout << "TO client:\n" << xml << "\n"; /*if there is no error,
i.e. on success, the server prints the message that was sent.*/
// / \
// /_!_\
/*the problem is that
the messages that are lost don't appear on the client side,
but they appear here on the server! */
if (((string) xml).find("<ack.>")==string::npos){
UDT::close(cur_udt);
cur.set_udt_socket_in(NULL); //close the socket
}
(*(cur.xml_msgs)).pop();
}
}
}
//...
client's relevant code:
//...
#define MSGBUFSIZE 1024
char msgbuf[MSGBUFSIZE];
UDTSOCKET client;
ofstream myfile;
//...
main(int argc, char *argv[]){
//...
// connect to the server, implict bind
if (UDT::ERROR == UDT::connect(client, (sockaddr*)&serv_addr, sizeof(serv_addr))){
cout << "error in connect();" << endl;
return 0;
}
myfile.open("./log.txt", ios::app);
send(xml);
char* cur_xml;
do{
cur_xml = receive(); //wait for an ACK or a new message...
myfile << cur_xml << endl << endl; // / \
/* /_!_\ the lost messages don't appear on the website
neither on this log file.*/
} while (((string) cur_xml).find("<ack.>")!=string::npos);
cout << cur_xml << endl;
myfile.close();
UDT::close(client);
return 0;
}
char* receive(){
if (UDT::ERROR == UDT::recv(client, msgbuf, MSGBUFSIZE, 0)){
// / \
/* /_!_\ when a message is not well received
this code is usually reached, and an error is printed.*/
cout << "error in recv();" << endl;
myfile << "error in recv();" << endl;
myfile << "recv: " << UDT::getlasterror().getErrorMessage() << endl << endl;
return 0;
}
return msgbuf;
}
void* send(string xml){
if (UDT::ERROR == UDT::send(client, xml.c_str(), strlen(xml.c_str())+1, 0)){
cout << "error in send();" << endl;
myfile << "error in send();" << endl;
myfile << "send: " << UDT::getlasterror().getErrorMessage() << endl << endl;
return 0;
}
}
Thank you for any help!
PS. I tried to increase the linger time on close(), after finding the link http://udt.sourceforge.net/udt4/doc/opt.htm, adding the following to the server's code:
struct linger l;
l.l_onoff = 1;
l.l_linger = ...; //a huge value in seconds...
UDT::setsockopt(*udt_socket_ptr, 0, UDT_LINGER, &l, sizeof(l));
but the problem is still the same...
PPS. the other parts of the communication in the server side are: (note: it seams for me that they are not so relevant)
main(int argc, char *argv[]){
char msgbuf[MSGBUFSIZE];
UDTSOCKET serv = UDT::socket(AF_INET, SOCK_STREAM, 0);
sockaddr_in my_addr;
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(PORT);
my_addr.sin_addr.s_addr = INADDR_ANY;
memset(&(my_addr.sin_zero), '\0', sizeof(my_addr.sin_zero));
if (UDT::ERROR == UDT::bind(serv, (sockaddr*)&my_addr, sizeof(my_addr))){
cout << "error in bind();";
return 0;
}
UDT::listen(serv, 1);
int namelen;
sockaddr_in their_addr;
while (true){
UDTSOCKET recver = UDT::accept(serv, (sockaddr*)&their_addr, &namelen);
if (UDT::ERROR == UDT::recv(recver, msgbuf, MSGBUFSIZE, 0)){
//this recv() function is called only once for each aqccept(), because the clients call CGI scripts via a browser, they need to call a new CGI script with a new UDT socket for each request (this in in agreement to the clients' code presented before).
cout << "error in recv();" << endl;
}
char* player_xml = (char*) &msgbuf;
cur_result = process_request((char*) &msgbuf, &recver, verbose); //ACK
}
}
struct result process_request(char* xml, UDTSOCKET* udt_socket_ptr, bool verbose){
//parse the XML...
//...
player* cur_ptr = get_player(me); //searches in a vector of player, according to the string "me" of the XML parsing.
UDTSOCKET* udt_ptr = (UDTSOCKET*) calloc(1, sizeof(UDTSOCKET));
memcpy(udt_ptr, udt_socket_ptr, sizeof(UDTSOCKET));
if (cur_ptr==NULL){
//register the player:
player* this_player = (player*) calloc(1, sizeof(player));
//...
}
}
else if (strcmp(request_type.c_str(), "info_waitformsg")==0){
if (udt_ptr!=NULL){
cur_ptr->set_udt_socket_in(udt_ptr);
if (!(*(cur_ptr->xml_msgs)).empty()){
send_msg_in(*cur_ptr, NULL, true);
}
}
}
else{ //messages that get instant response from the server.
if (udt_ptr!=NULL){
cur_ptr->set_udt_socket_out(udt_ptr);
}
if (strcmp(request_type.c_str(), "info_chat")==0){
info_chat cur_info;
to_object(&cur_info, me, request_type, msg_ptr); //convert the XML string values to a struct
process_chat_msg(cur_info, xml);
}
/* else if (...){ //other types of messages...
}*/
}
}
void process_chat_msg(info_chat cur_info, char* xml_in){
player* player_ptr=get_player(cur_info.me);
if (player_ptr){
int i=search_in_matches(matches, cur_info.match_ID);
if (i>=0){
match* cur_match=matches[i];
vector<player*> players_in = cur_match->followers;
int n=players_in.size();
for (int i=0; i<n; i++){
if (players_in[i]!=msg_owner){
send_msg_in(*(players_in[i]), xml, flag);
}
}
}
}
}
Looking at the UDT source code at http://sourceforge.net/p/udt/git/ci/master/tree/udt4/src/core.cpp, the error message "Connection was broken" is produced when either of the Boolean flags m_bBroken or m_bClosing is true and there is no data in the receive buffer.
Those flags are set in just a few cases:
In sections of code marked "should not happen; attack or bug" (unlikely)
In deliberate close or shutdown actions (don't see this happening in your code)
In expiration of a timer that checks for peer activity (the likely culprit)
In that source file at line 2593 it says:
// Connection is broken.
// UDT does not signal any information about this instead of to stop quietly.
// Application will detect this when it calls any UDT methods next time.
//
m_bClosing = true;
m_bBroken = true;
// ...[code omitted]...
// app can call any UDT API to learn the connection_broken error
Looking at the send() call, I don't see anywhere that it waits for an ACK or NAK from the peer before returning, so I don't think a successful return from send() on the server side is indicative of successful receipt of the message by the client.
You didn't show the code on the server side that binds to the socket and listens for responses from the client; if the problem is there then the server might be happily sending messages and never listening to the client that is trying to respond.
UDP is not a guaranteed-transmission protocol. A host will send a message, but if the recipient does not receive it, or if it is not received properly, no error will be raised. Therefore, it is commonly used in applications that require speed over perfect delivery, such as games. TCP does guarantee delivery, because it requires that a connection be set up first, and each message is acknowledged by the client.
I would encourage you to think about whether you actually need guaranteed receipt of that data, and, if you do, consider using TCP.
I am trying to write a threaded function that sends system information via Tcp/ip over the local network to another computer. I have been using sockets to achieve this and this has worked out quite allright thus far. But I am now at a point where this usually works but around 30% of the time I get error messages telling me that the socket can not be opened. I use the activeSocket library for the sockets.
#include "tbb/tick_count.h"
#include "ActiveSocket.h"
using namespace std;
CActiveSocket socket;
extern int hardwareStatus;
int establishTCP() {
char time[11];
int communicationFailed = 0;
memset(&time, 0, 11);
socket.Initialize();
socket.SetConnectTimeout(0, 20);
socket.SetSendTimeout(0, 20);
return communicationFailed;
}
int monitor() {
cout << "Monitor: init continious monitoring" << endl;
int communicationFailed;
tbb::tick_count monitorCounter = tbb::tick_count::now();
while (!closeProgram) {
tbb::tick_count currentTick = tbb::tick_count::now();
tbb::tick_count::interval_t interval;
interval = currentTick - monitorCounter;
if (interval.seconds() > 2) {
monitorCounter = tbb::tick_count::now();
communicationFailed = 1;
char buffer[256];
sprintf(buffer, "%d;", hardwareStatus);
establishTCP();
char *charip = new char[monitoringIP.size() + 1];
charip[monitoringIP.size()] = 0;
memcpy(charip, monitoringIP.c_str(), monitoringIP.size());
const uint8* realip = (const uint8 *) charip;
int monitorCount = 0;
cout << "Monitor: " << buffer << endl;
while (communicationFailed == 1 && monitorCount < 2) {
monitorCount++;
if (socket.Open(realip, 2417)) {
if (socket.Send((const uint8 *) buffer, strlen(buffer))) {
cout << "Monitor: Succeeded sending data" << endl;
communicationFailed = 0;
socket.Close();
} else {
socket.Close();
communicationFailed = 1;
cout << "Monitor: FAILED TO SEND DATA" << endl;
}
} else {
socket.Close();
communicationFailed = 1;
cout << "Monitor: FAILED TO OPEN SOCKET FOR DATA" << endl;
}
}
if (monitorCount == 2) cout << "Monitor: UNABLE TO SEND DATA" << endl;
}
}
return communicationFailed;
}
I think I am doing something wrong with these functions and that the problem is not on the other side of the line where this data is received. Can anyone see any obvious mistakes in this code that could cause the failure? I keep getting my own cout message "Monitor: FAILED TO OPEN SOCKET FOR DATA"
EDIT: With telnet everything works fine, 100% of the time
You can use netstat to check that the server is listening on the port and connections are being established. Snoop is another good application in your Armour for finding out what is going wrong. Another possibility is to use telnet to see if the client can connect to that IP address and port. As to the code I will take a look at it later to see if something has gone awry.
socket is a global variable. It might be re-used concurrently between two threads or sequentially inside one thread. In fact, the while(~closeProgram) loop indicates that you intend to use it sequentially.
Some documentation for CActiveSocket::Open reads: "Connection-based protocol sockets (CSocket::SocketTypeTcp) may successfully call Open() only once..."
Perhaps your program fails when you call .Open() twice on the same object.
I eventually found out the problem with my code. As the connection was unstable and working for 70% of the time it seemed to be a timeout issue. I removed the two timeout settings
socket.SetConnectTimeout(0, 20);
socket.SetSendTimeout(0, 20);
Now it works perfectly fine, thanks for the troubleshooting tips though!
I begin to develop my tool, which works with net at the TCP level, which will present simple functions of web-server.
In testing my program I have got very bad mistakes:
Memory leaks
Creating thousands of threads immediately
In taskmgr.exe you may see about ~1,5 of threads and about ~50kb of allocated memory.
Also, I compiled program as 32 bit, but in vmmap utility you may see a lot of 64 bit stacks. My OS is 64 bit, but in taskmgr.exe you may see *32 , I don’t know how 32 bit program uses 64 bit stack, maybe it’s normal for launching 32 bit program in 64 bit OS, but I have no knowledge about this design of OS, so I shall be very pleased , if you give me a piece of advice on this question.
So, why did my program creates immediately a lot of threads? ( I guess , cause of while(true) block ).
But , I want the next:
Create each thread for each new request
When request has been handled, then terminate the thread and free the memory
How should I remake my code?
Thanks!
Here is my code ( MS VC ++ 9 ):
#include <iostream>
#include <Windows.h>
#pragma comment(lib, "Ws2_32.lib")
typedef struct Header
{
friend struct Net;
private:
WORD wsa_version;
WSAData wsa_data;
SOCKET sock;
SOCKADDR_IN service;
char *ip;
unsigned short port;
public:
Header(void)
{
wsa_version = 0x202;
ip = "0x7f.0.0.1";
port = 0x51;
service.sin_family = AF_INET;
service.sin_addr.s_addr = inet_addr(ip);
service.sin_port = htons(port);
}
} Header;
typedef struct Net
{
private:
int result;
HANDLE thrd;
DWORD exit_code;
void WSAInit(WSAData *data, WORD *wsa_version)
{
result = WSAStartup(*wsa_version, &(*data));
if(result != NO_ERROR)
{
std::cout << "WSAStartup() failed with the error: " << result << std::endl;
}
else
{
std::cout << (*data).szDescription << " " << (*data).szSystemStatus << std::endl;
}
}
void SocketInit(SOCKET *my_socket)
{
(*my_socket) = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if((*my_socket) == INVALID_SOCKET)
{
std::cout << "Socket initialization failed with the error: " << WSAGetLastError() << std::endl;
WSACleanup();
}
else
{
std::cout << "Socket initialization successful!" << std::endl;
}
}
void SocketBind(SOCKET *my_socket, SOCKADDR_IN *service)
{
result = bind((*my_socket), (SOCKADDR*)&(*service), sizeof(*service));
if(result == SOCKET_ERROR)
{
std::cout << "Socket binding failed with the error: " << WSAGetLastError() << std::endl;
closesocket((*my_socket));
WSACleanup();
}
else
{
std::cout << "Socket binding successful!" << std::endl;
}
result = listen(*my_socket, SOMAXCONN);
if(result == SOCKET_ERROR)
{
std::cout << "Socket listening failed with the error: " << WSAGetLastError() << std::endl;
}
else
{
std::cout << "Listening to the socket..." << std::endl;
}
}
static void SocketAccept(SOCKET *my_socket)
{
SOCKET sock_accept = accept((*my_socket), 0, 0);
if(sock_accept == INVALID_SOCKET)
{
std::cout << "Accept failed with the error: " << WSAGetLastError() << std::endl;
closesocket(*my_socket);
WSACleanup();
}
else
{
std::cout << "Client socket connected!" << std::endl;
}
char data[0x400];
int result = recv(sock_accept, data, sizeof(data), 0);
HandleRequest(data, result);
char *response = "HTTP/1.1 200 OK\r\nServer: Amegas.sys-IS/1.0\r\nContent-type: text/html\r\nSet-Cookie: ASD643DUQE7423HFDG; path=/\r\nCache-control: private\r\n\r\n<h1>Hello World!</h1>\r\n\r\n";
result = send(sock_accept, response, (int)strlen(response), 0);
if(result == SOCKET_ERROR)
{
std::cout << "Sending data via socket failed with the error: " << WSAGetLastError() << std::endl;
closesocket(sock_accept);
WSACleanup();
}
else
{
result = shutdown(sock_accept, 2);
}
}
static void HandleRequest(char response[], int length)
{
std::cout << std::endl;
for(int i = 0; i < length; i++)
{
std::cout << response[i];
}
std::cout << std::endl;
}
static DWORD WINAPI Threading(LPVOID lpParam)
{
SOCKET *my_socket = (SOCKET*)lpParam;
SocketAccept(my_socket);
return 0;
}
public:
Net(void)
{
Header *obj_h = new Header();
WSAInit(&obj_h->wsa_data, &obj_h->wsa_version);
SocketInit(&obj_h->sock);
SocketBind(&obj_h->sock, &obj_h->service);
while(true)
{
thrd = CreateThread(NULL, 0, &Net::Threading, &obj_h->sock, 0, NULL);
//if(GetExitCodeThread(thrd, &exit_code) != 0)
//{
// ExitThread(exit_code);
//}
}
delete &obj_h;
}
} Net;
int main(void)
{
Net *obj_net = new Net();
delete &obj_net;
return 0;
}
You should create the thread AFTER you accept a connection, not before.
What you are doing is creating a ton of threads, and then having each of them wait for a connection. Many of them have nothing to do. I don't even know if Windows' accept call is thread-safe - you might end up with multiple threads handling the same connection.
What you need to do instead is, in your main loop (Net's constructor while(true)), you need to call accept(). Since accept() blocks until it has a connection, this will cause the main thread to wait until somebody tries to connect. Then, when they do, you create another thread (or process - more likely on UNIX) to handle that connection. So, your loop now looks like this:
SOCKET sock_accept = accept((*my_socket), 0, 0);
if(sock_accept == INVALID_SOCKET)
{
std::cout << "Accept failed with the error: " << WSAGetLastError() << std::endl;
closesocket(*my_socket);
WSACleanup();
}
else
{
std::cout << "Client socket connected!" << std::endl;
}
thrd = CreateThread(NULL, 0, &Net::Threading, &obj_h->sock, 0, NULL);
//push back thrd into a std::vector<HANDLE> or something like that
//if you want to keep track of it for later: there's more than one thread
Then, delete that code you moved from SocketAccept into this loop. And then, for cosmetic purposes, I would change the name of SocketAccept to SocketHandleConnection.
Now, when your thread starts, it already has a connection, and all you need to do is handle the data (e.g. what you do starting at char data[0x400]).
If you want to handle cleanup for connections, there are a few ways to do this. One, since you are threaded, you can have the thread do its own cleanup. It shares memory with the main process, so you can do this. But in this example, I don't see anything you need to clean up.
Lastly, I think you don't understand what ExitThread does. According to MSDN:
ExitThread is the preferred method of exiting a thread in C code. However, in C++ code,
the thread is exited before any destructors can be called or any other automatic cleanup
can be performed. Therefore, in C++ code, you should return from your thread function.
So it appears that you don't need to call ExitThread- you just return from your function and the thread exits automatically. You don't need to call it from the main thread.
Finally, you should really (if you can) use the new standard C++ threads in c++11, and then if you put in a little bit of effort to port your code over to boost::asio, you'll have a completely cross platform application, with no need for windows API C ugliness :D
DISCLAIMER: I only have a passing understanding of Windows as most of my experience is related to UNIX. I have attempted to be as accurate as I can but if I have any misconceptions about how this knowledge converts over to Windows, well, I warned you.
Why are you creating threads in an infinite loop? This will, of course, create tons of threads. I am referring to this piece of code:
while(true)
{
thrd = CreateThread(NULL, 0, &Net::Threading, &obj_h->sock, 0, NULL);
}