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TCP Server
Hello, i have written a simple TCP server. But when i tried make it multithreaded i screw up something. Can someone help me to find out what's wrong with it?
Code:
#include <cstdlib>
#include <iostream>
#include <winsock2.h>
#include <ws2tcpip.h>
//Zmienne stale
#define DEFAULT_BUFLEN 512
#define MAX_CLIENTS 100
using namespace std;
//Deklaracja funkcji
DWORD WINAPI ServeClient(LPVOID lpParam);
//Zmienne globalne
typedef struct TThreadInfo {
int ID;
int cos1;
} TTHREADINFO, *PTTHREADINFO;
char *D_PORT = "6698";
bool ShutDown = 0;
HANDLE ClientThread [MAX_CLIENTS];
HANDLE ListenerHandle;
DWORD ClientThreadID [MAX_CLIENTS];
WSADATA wsaData;
SOCKET ListenSocket = INVALID_SOCKET;
SOCKET ClientSocket = INVALID_SOCKET;
struct addrinfo *result = NULL;
struct addrinfo *ptr = NULL;
struct addrinfo hints;
//Rest
bool StartWSA(void)
{
if (WSAStartup(MAKEWORD(2,2), &wsaData) != 0) return 0; else return 1;
}
bool InitSock(void)
{
ZeroMemory(&hints, sizeof (hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;
// Resolve the local address and port to be used by the server
if ((getaddrinfo(NULL, D_PORT, &hints, &result)) != 0) return 0; else return 1;
}
bool CreateSock(void)
{
// Create a SOCKET for the server to listen for client connections
ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
if (ListenSocket == INVALID_SOCKET) return 0; else return 1;
//
// for(int a=0;a<MAX_CLIENTS;a++) ClientSocket[a] = INVALID_SOCKET;
}
bool BindSock(void)
{
// Setup the TCP listening socket
int _result;
_result = bind( ListenSocket, result->ai_addr, (int)result->ai_addrlen);
if (_result == SOCKET_ERROR) return 0; else return 1;
}
bool Listener(void)
{
if ( listen( ListenSocket, SOMAXCONN ) == SOCKET_ERROR ) return 0; else return 1;
}
DWORD WINAPI ServeClient(LPVOID lpParam)
{
printf("Serving client..");
bool CloseConnection = 0;
char recvbuf[DEFAULT_BUFLEN];
int sResult, cResult;
int recvbuflen = DEFAULT_BUFLEN;
SOCKET current_sock;
current_sock = (SOCKET)lpParam;
do {
cResult = recv(current_sock, recvbuf, recvbuflen, 0);
if (cResult > 0) {
printf("Bytes received: %d\n", cResult);
// Echo the buffer back to the sender
sResult = send(current_sock, recvbuf, cResult, 0);
if (sResult == SOCKET_ERROR) {
printf("send failed: %d\n", WSAGetLastError());
closesocket(current_sock);
WSACleanup();
CloseConnection = 1;
return 1;
}
printf("Bytes sent: %d\n", sResult);
} else {
printf("Connection error..");
closesocket(current_sock);
WSACleanup();
CloseConnection = 1;
return 1;
}
} while (!CloseConnection);
}
int main(int argc, char *argv[])
{
if (argv[1] != 0) D_PORT = argv[1];
if (!StartWSA())
{
printf("- WSA Startup error\n");
system("PAUSE");
return 1;
}
printf("* WSA started\n");
if (!InitSock())
{
printf("- GetAddrInfo failed\n");
WSACleanup();
system("PAUSE");
return 1;
}
printf("* Socket initialized\n");
if (!CreateSock())
{
printf("- Error at socket\n");
freeaddrinfo(result);
WSACleanup();
system("PAUSE");
return 1;
}
printf("* Socket created\n");
if (!BindSock())
{
printf("- Bind failed\n");
freeaddrinfo(result);
closesocket(ListenSocket);
WSACleanup();
system("PAUSE");
return 1;
}
printf("* Binging socket success\n");
if (!Listener())
{
printf("- Listen failed\n");
closesocket(ListenSocket);
WSACleanup();
system("PAUSE");
return 1;
}
printf("* Listener started\n");
printf("* Server is running :\n");
printf(" - IP : 127.0.0.1\n");
printf(" - PORT : %s\n", D_PORT);
do
{
ClientSocket = accept(ListenSocket, NULL, NULL);
if (ClientSocket == INVALID_SOCKET) {
printf("Client connection failed\n");
// closesocket(ListenSocket);
//WSACleanup();
}
printf("Client connected");
DWORD thread;
CreateThread(
NULL, // no security attributes
0, // use default stack size
ServeClient, // thread function
(LPVOID)ClientSocket, // argument to thread function
0, // use default creation flags
&thread);
ClientSocket = INVALID_SOCKET;
}
while (true);
system("PAUSE");
closesocket(ListenSocket);
WSACleanup();
return EXIT_SUCCESS;
}
The thing happen is that im getting in infinite loop here :
Code:
do
{
ClientSocket = accept(ListenSocket, NULL, NULL);
if (ClientSocket == INVALID_SOCKET) {
printf("Client connection failed\n");
// closesocket(ListenSocket);
//WSACleanup();
}
printf("Client connected");
DWORD thread;
CreateThread(
NULL, // no security attributes
0, // use default stack size
ServeClient, // thread function
(LPVOID)ClientSocket, // argument to thread function
0, // use default creation flags
&thread);
ClientSocket = INVALID_SOCKET;
}
while (true);
Why it's not waiting for next connection and getting old one?
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When the client closes the connection recv will return 0. You should not be treating that as an error condition and subsequently cleaning up Winsock via WSACleanup.
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Oh yea i completly forgot i've changed this. It works now, thanks.
One more question how do i get IP, like i want to know client's ip who connected?
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instead of calling accept like this:
Code:
ClientSocket = accept(ListenSocket, NULL, NULL);
try passing it a sockaddr_in struct and its length for it to fill with the client info.
accept() winsock reference
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Thanks it works this way
Code:
struct sockaddr_in clientinfo;
int cilen = sizeof(struct sockaddr);
ClientSocket = accept(ListenSocket, (LPSOCKADDR)&clientinfo, &cilen);
printf(inet_ntoa(clientinfo.sin_addr));
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One more question, sometimes when i try send two packets, server interprets it as one packet like :
1 - I send byte 0x01
2 - I send buff with text (0x5A3D7C....)
The server interprets it as one : 015A3D7C..
So i do something wrong or it is how it works? In delphi i hadn't that problem, everytime i got separated packets.
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That's how TCP streams work.
You get guaranteed transmission of the bytes in the order you sent them.
A typical TCP stream sends either 'length' bytes, or uses a record separator (like newline) to mark boundaries in the information stream.
