server.c

LINUX网络编程文档

/* Examples for Linux Network Programming----server.c */
#ifndef unix
#define WIN32
#include <windows.h>
#include <winsock.h>
#else
#define closesocket close
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#endif

#include <stdio.h>
#include <string.h>

#define PROTORORT 5193		/* default protocol port number */
#define QLEN	6		/* size of request queue*/

int visits = 0; 		/* counts client connections */
/*-----------------------------------------------------------
*Program: server
*Purpose: allocate a socket, and then repeatedly execute the following:
*		(1)wait for the next connection from a client
		(2)send a short message to the client
		(3)close the connection
		(4)go back to step(1)
*Syntax: server[port]

*		port - protocol port number to use
*
*Notes: the port argument is optional. If no port is specified,the 
*	server uses the default given by PROTOPORT.
*-----------------------------------------------------------
*/
main(argc,argv)
int argc;
char *argv[];
{
  struct	hostent *ptrh;		/*pointer to a host table entry*/
  struct	protoent *ptrp;		/*pointer to a protocol table entry*/
  struct	sockaddr_in sad;	/*structure to hold server's address*/
  struct	sockaddr_in cad;	/*structure to hold client's address*/
  int		sd,sd2;			/*socket descriptor*/
  int 		port;			/*protocol prot number*/
  int 		alen;			/*lenth of address*/
  char		buf[1000];		/*buffer for data from the server */
  #ifdef WIN32
  	WSADATA wsaData;
  	WSAStartup(0x0101, &wsaData);
  #endif
  memset((char *)&sad,0,sizeof(sad));	/*clear sockaddr structure*/
  sad.sin_family = AF_INET;		/*set family to Internet */
  sad.sin_addr.s_addr = INADDR_ANY;	/*set the local IP address */
  /*Check command- line argument for portocol port and extract */
  /*port number if one is specifie. Otherwise, use the default*/
  /*port value given by constant PROTOPORT */
  if(argc >1){			/*if argument specified*/
  	port = atoi(argv[1]);	/*convert to binary */
  }else{
  	port = PROTOPORT;	/*use default port number*/
  }
  if(port>0)			/*test for illegal value*/
  	sad.sin_port = htons(u_short)port);
  				/*print error message and exit */
  else{
  	fprintf(stderr,"bad port number %s\n",argv[1]);
  	exit(1);
  }
  /*Map TCP transport protocol name to protocol number. */
  if( ((int)(ptrp = getprotobyname("tcp"))) ==0{
  	fprintf(stderr,"cannot map \ "tcp\" to protocol number);
  	exit(1);
  }

  /*Create a socket. */

  sd=socket(PF_INET,SOCK_STREAM,ptrp->p_proto);
  if(sd<0){
	fprintf(stderr,"socket creation failed\n");
	exit(1);
  }
  /*Bind a local address to the socket */
  
  if(bind(sd,(struct sockaddr *)&sad,sizeof(sad))<0){
  	fprintf(stderr,"bind failed\n");
  	exit(1);
  }
  
  /*Specify size of request queue */
  
  if(listen(sd, QLEN)<0){
  	fprintf(stderr, "listen failed\n"):
  	exit(1);
  }
  
  /* Main server loop - accept and handle requests */
  
  while(1){
  	alen = sizeof(cad);
  	if((sd2=accept(sd,(struct sockaddr *)&cad,&alen))<0){
  		fprintf(stderr,"accept failed\n"):
  		exit(1);
  	}
  	visits++;
  	sprintf(buf,"This server has been contacted %d time%s\n",visits,visits==1?".":s.");
  	send(sd2,buf,strlen(buf),0);
  	closesocket(sd2);
  }
 }