SIMPLES.C

/******************************************************************************\ 
* simples.c - Simple TCP/UDP server using Winsock 1.1 
*       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 
#define DEFAULT_PROTO SOCK_STREAM // TCP 
 
void Usage(char *progname) { 
fprintf(stderr,"Usage\n%s -p [protocol] -e [endpoint] -i [interface]\n", 
progname); 
fprintf(stderr,"Where:\n\tprotocol is one of TCP or UDP\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 TCP,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 retval; 
int fromlen; 
int i; 
int socket_type = DEFAULT_PROTO; 
struct sockaddr_in local, from; 
WSADATA wsaData; 
SOCKET listen_socket, msgsock; 
 
/* Parse arguments */ 
if (argc >1) { 
for(i=1;i <argc;i++) { 
if ( (argv[i][0] == '-') || (argv[i][0] == '/') ) { 
switch(tolower(argv[i][1])) { 
case 'p': 
if (!stricmp(argv[i+1], "TCP") ) 
socket_type = SOCK_STREAM; 
else if (!stricmp(argv[i+1], "UDP") ) 
socket_type = SOCK_DGRAM; 
else 
Usage(argv[0]); 
i++; 
break; 
 
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]); 
} 
 
local.sin_family = AF_INET; 
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, socket_type,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. This is most useful when the application is a  
// server that has a well-known port that clients know about in advance. 
// 
 
if (bind(listen_socket,(struct sockaddr*)&local,sizeof(local) )  
== SOCKET_ERROR) { 
fprintf(stderr,"bind() failed with error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
 
// 
// So far, everything we did was applicable to TCP as well as UDP. 
// However, there are certain steps that do not work when the server is 
// using UDP. 
// 
 
// We cannot listen() on a UDP socket. 
 
if (socket_type != SOCK_DGRAM) { 
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, protocol %s\n",argv[0],port, 
(socket_type == SOCK_STREAM)?"TCP":"UDP"); 
while(1) { 
fromlen =sizeof(from); 
// 
// accept() doesn't make sense on UDP, since we do not listen() 
// 
if (socket_type != SOCK_DGRAM) { 
msgsock = accept(listen_socket,(struct sockaddr*)&from, &fromlen); 
if (msgsock == INVALID_SOCKET) { 
fprintf(stderr,"accept() error %d\n",WSAGetLastError()); 
WSACleanup(); 
return -1; 
} 
printf("accepted connection from %s, port %d\n",  
inet_ntoa(from.sin_addr), 
htons(from.sin_port)) ; 
 
} 
else 
msgsock = listen_socket; 
 
// 
// In the case of SOCK_STREAM, the server can do recv() and  
// send() on the accepted socket and then close it. 
 
// However, for SOCK_DGRAM (UDP), the server will do 
// recvfrom() and sendto()  in a loop. 
 
if (socket_type != SOCK_DGRAM) 
retval = recv(msgsock,Buffer,sizeof (Buffer),0 ); 
else { 
retval = recvfrom(msgsock,Buffer,sizeof (Buffer),0, 
(struct sockaddr *)&from,&fromlen); 
printf("Received datagram from %s\n",inet_ntoa(from.sin_addr)); 
} 
 
if (retval == SOCKET_ERROR) { 
fprintf(stderr,"recv() failed: error %d\n",WSAGetLastError()); 
closesocket(msgsock); 
continue; 
} 
if (retval == 0) { 
printf("Client closed connection\n"); 
closesocket(msgsock); 
continue; 
} 
printf("Received %d bytes, data [%s] from client\n",retval,Buffer); 
 
printf("Echoing same data back to client\n"); 
if (socket_type != SOCK_DGRAM) 
retval = send(msgsock,Buffer,sizeof(Buffer),0); 
else 
retval = sendto(msgsock,Buffer,sizeof (Buffer),0, 
(struct sockaddr *)&from,fromlen); 
if (retval == SOCKET_ERROR) { 
fprintf(stderr,"send() failed: error %d\n",WSAGetLastError()); 
} 
if (socket_type != SOCK_DGRAM){ 
printf("Terminating connection\n"); 
closesocket(msgsock); 
} 
else  
printf("UDP server looping back for more requests\n"); 
continue; 
} 
}