IOCTL.C

/******************************************************************************\ 
* ioctl.c - TCP server 
* 
*       This is a part of the Microsoft Source Code Samples. 
*       Copyright 1996 - 1998 Microsoft Corporation. 
*       All rights reserved. 
*       This source code is only intended as a supplement to 
*       Microsoft Development Tools and/or WinHelp documentation. 
*       See these sources for detailed information regarding the 
*       Microsoft samples programs. 
\******************************************************************************/ 
 
 
 
#define WIN32_LEAN_AND_MEAN 
#include <winsock2.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <string.h> 
 
#define DEFAULT_PORT 5001 
 
int ReadAndEcho(SOCKET , char *,int ) ; 
int WriteMessage(SOCKET , char *,int ) ; 
 
void Usage(char *progname) { 
fprintf(stderr,"Usage\n%s -e [endpoint] -i [interface]\n", 
progname); 
fprintf(stderr,"Where:\n"); 
fprintf(stderr,"\tendpoint is the port to listen on\n"); 
fprintf(stderr,"\tinterface is the ipaddr (in dotted decimal notation)"); 
fprintf(stderr," to bind to\n"); 
fprintf(stderr,"Defaults are 5001 and INADDR_ANY\n"); 
WSACleanup(); 
exit(1); 
} 
int main(int argc, char **argv) { 
 
char Buffer[128]; 
char *interface= NULL; 
unsigned short port=DEFAULT_PORT; 
int fromlen; 
int i, ioctl_opt =1; 
struct sockaddr_in local, from; 
WSADATA wsaData; 
SOCKET listen_socket, msgsock; 
fd_set readfds, writefds, exceptfds; 
 
/* Parse arguments */ 
if (argc >1) { 
for(i=1;i <argc;i++) { 
if ( (argv[i][0] == '-') || (argv[i][0] == '/') ) { 
switch(tolower(argv[i][1])) { 
case 'i': 
interface = argv[++i]; 
break; 
case 'e': 
port = atoi(argv[++i]); 
break; 
default: 
Usage(argv[0]); 
break; 
} 
} 
else 
Usage(argv[0]); 
} 
} 
 
if (WSAStartup(0x202,&wsaData) == SOCKET_ERROR) { 
fprintf(stderr,"WSAStartup failed with error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
 
if (port == 0){ 
Usage(argv[0]); 
} 
 
// 
// The fd sets should be zeroed out before using them to prevent errors. 
FD_ZERO(&readfds); 
FD_ZERO(&writefds); 
FD_ZERO(&exceptfds); 
memset(Buffer,0,sizeof(Buffer)); 
 
local.sin_family = AF_INET; 
 
// 
// bind to specific interface if desired. 
 
local.sin_addr.s_addr = (!interface)?INADDR_ANY:inet_addr(interface);  
 
/*  
 * Port MUST be in Network Byte Order 
 */ 
local.sin_port = htons(port); 
 
listen_socket = socket(AF_INET, SOCK_STREAM,0); // TCP socket 
if (listen_socket == INVALID_SOCKET){ 
fprintf(stderr,"socket() failed with error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
// 
// bind() associates a local address and port combination with the 
// socket just created.  
 
if (bind(listen_socket,(struct sockaddr*)&local,sizeof(local) )  
== SOCKET_ERROR) { 
fprintf(stderr,"bind() failed with error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
 
// 
// start listening on the socket for incoming connections 
// 
if (listen(listen_socket,5) == SOCKET_ERROR) { 
fprintf(stderr,"listen() failed with error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
printf("%s: Listening on port %d\n",argv[0],port); 
 
// 
// Set the socket to non-blocking mode. 
// 
if (ioctlsocket(listen_socket,FIONBIO,&ioctl_opt) == SOCKET_ERROR) { 
fprintf(stderr,"ioctlsocket failed %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
// 
// The structure of the loop below is very simple. We only accept one 
// connection at a time. As soon as another client connects, we 
// disconnect the first one, and start talking to the new client. 
// All this server does is to echo the data received on the socket 
// back to the client. 
// 
// This is not a very realistic server, but it does serve to show that 
// select() does not scale very well on win32. If we were dealing 
// with more than one client, we would have to have a list of sockets 
// that are in each fdset to be able to check them when select() 
// returns. 
// 
while(1) { 
 
// 
// A socket in the listen() state becomes ready to read when a 
// client connects to it. An accept() will complete without 
// blocking. 
// Since select sets the sockets that are ready to be read from or 
// written to, we have to include listen_socket in the fdset each time 
// through the loop. 
// 
 
FD_SET(listen_socket,&readfds); 
 
i = select(0,&readfds,&writefds,&exceptfds,NULL); 
if (i == SOCKET_ERROR) { 
fprintf(stderr,"select failed %d\n",WSAGetLastError()); 
} 
if (i==0){ 
fprintf(stderr,"Select returned no fds ready\n"); 
} 
 
if (FD_ISSET(listen_socket, &readfds)){ 
// 
// close the previous client socket.  
// We must also clear it from the fdset to prevent select() 
// from failing. 
// 
closesocket(msgsock); 
FD_CLR(msgsock,&readfds); 
FD_CLR(msgsock,&writefds); 
fromlen = sizeof(from); 
msgsock= accept(listen_socket,(struct sockaddr*)&from,&fromlen); 
if (msgsock == INVALID_SOCKET) { 
fprintf(stderr,"accept failed %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
FD_SET(msgsock,&writefds); 
FD_SET(msgsock,&readfds); 
continue; 
} 
if (FD_ISSET(msgsock,&readfds) ) { 
// 
// socket is ready to read, i.e., there is data on the socket. 
// 
if (ReadAndEcho(msgsock,Buffer,sizeof(Buffer))<0) { 
fprintf(stderr,"terminating connection\n"); 
FD_CLR(msgsock,&readfds); 
FD_CLR(msgsock,&writefds); 
closesocket(msgsock); 
continue; 
} 
} 
if (FD_ISSET(msgsock,&writefds) ){ 
if (WriteMessage(msgsock,Buffer,sizeof(Buffer)) <=0) { 
fprintf(stderr,"terminating connection\n"); 
FD_CLR(msgsock,&readfds); 
FD_CLR(msgsock,&writefds); 
closesocket(msgsock); 
continue; 
} 
} 
FD_SET(msgsock,&writefds); 
FD_SET(msgsock,&readfds); 
} 
} 
int ReadAndEcho(SOCKET insock, char *Buffer,int size) { 
int rc; 
 
rc = recv(insock,Buffer,size,0); 
 
if (rc == SOCKET_ERROR) { 
fprintf(stderr,"recv() failed with error %d\n",WSAGetLastError()); 
return -1; 
} 
if (rc ==0) { 
fprintf(stderr,"Connection closed by client\n"); 
return 0; 
} 
printf("Received [%s] from client\n",Buffer); 
return rc; 
} 
int WriteMessage(SOCKET outsock, char *Buffer,int size) { 
int rc; 
int lasterr; 
 
printf("Sending [%s] to client\n",Buffer); 
rc = send(outsock,Buffer,size, 0); 
 
if (rc == SOCKET_ERROR) { 
  lasterr = WSAGetLastError(); 
  if (lasterr == WSAEWOULDBLOCK) 
return 0; 
  else { 
fprintf(stderr,"send() failed with error %d\n",lasterr); 
return -1; 
  } 
} 
if (rc ==0) { 
fprintf(stderr,"Connection closed by client\n"); 
} 
return rc; 
}