please review: simple winsock example for sending data over a nonblocking socket
From: Daniel (softwareengineer98037_at_yahoo.com)
Date: 02/26/05
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Date: Fri, 25 Feb 2005 17:17:02 -0800
please review: simple winsock example for sending data over a nonblocking
socket
I put together a simple winsock example for sending data over a nonblocking
socket because i could not find such a simple example on the internet.
please tell me if you see any MEMORY LEAKS, RESOURSE MISUSE, or other
critical issues with this code: http://rafb.net/paste/results/mZAzaI55.html
I would like this to be perfect as i will use it over and over. Any
meaningfull and focused suggestions appreciated. In no case should this code
hang because of any kind of network or remote server issue. And in no case
should it leak memory or resources:
#include "stdafx.h"
#include <winsock2.h>
#pragma comment(lib, "ws2_32.lib")
int main(void);
int genericstream(char*, int, char*, int);
int main(void)
{
char* pData = new char[12];
char* pIp = new char[11];
memcpy((void*)pData, (const void*)"hello world", 11);
pData[11] = ' ';
memcpy((void*)pIp, (const void*)"3.3.3.222", 10);
pIp[10] = '\0';
int ret = genericstream(pData, 12, pIp, 11);
pData[4] = '\0';
delete[] pData;
delete[] pIp;
return 0;
}
int genericstream(char* a, int iLen, char* pIp, int iIpLen)
{
int sock;
try
{
WSADATA wsaData;
//load winsock dlls if not already loaded
if(WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
return 1;
}
//create a socket
sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock == INVALID_SOCKET)
{
WSACleanup();
return 1;
}
unsigned long ulMode = 1;
//make the socket connect operation
//return right away even if the
//remote computer hangs on connect
//e.g. nonblocking socket
ioctlsocket(sock, FIONBIO, &ulMode);
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = inet_addr( pIp );
clientService.sin_port = htons(8888);
memset(clientService.sin_zero, 0, 8);
//try to connect, should return SOCKET_ERROR most of the time as the
connect
//is on a nonblocking socket
if(connect( sock, (SOCKADDR*) &clientService, sizeof(clientService) ) ==
SOCKET_ERROR)
{
if(WSAGetLastError() == WSAEWOULDBLOCK)
{
fd_set fsConnect;
FD_ZERO(&fsConnect);
FD_SET(sock, &fsConnect);
timeval sTimeoutVal;
sTimeoutVal.tv_sec = (long)30;
sTimeoutVal.tv_usec = (long)0;
//wait up to 30 seconds for the socket to complete connecting, unless
the target computer, network or
//internet is hanging this should return with 1 right away
int retval = select(FD_SETSIZE, (fd_set *) NULL, &fsConnect, (fd_set *)
NULL, &sTimeoutVal);
if(retval != 1)
{
//connect timed out
//close socket and remove a winsock reference count
closesocket(sock);
WSACleanup();
return 1;
}
}
else
{
//connect failed right away, no need to select status of socket
//close socket and remove a winsock reference count
closesocket(sock);
WSACleanup();
return 1;
}
}
//send data
int iBytes = send(sock, a, iLen-1, 0);
if(iBytes == -1 || iBytes != iLen-1)
{
//send failed, perhaps target application or machine went down
//close socket and remove a winsock reference count
closesocket(sock);
WSACleanup();
return 1;
}
//close socket and remove a winsock reference count
closesocket(sock);
WSACleanup();
}
catch(...)
{
try
{
closesocket(sock);
WSACleanup();
}
catch(...)
{
}
return 1;
}
return 0;
}
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