#pragma	module	tcpip$tcp_server_sock			\
		"V5.4-00"

/*
 * © Copyright 1976, 2003 Hewlett-Packard Development Company, L.P.
 *
 * Confidential computer software.  Valid license  from  HP  and/or its
 * subsidiaries required for possession, use, or copying.
 *
 * Consistent with FAR 12.211 and 12.212, Commercial Computer Software,
 * Computer Software Documentation,  and  Technical Data for Commercial
 * Items  are  licensed to the U.S. Government under vendor's  standard
 * commercial license.
 *
 * Neither HP nor any of its subsidiaries shall be liable for technical
 * or editorial errors or omissions contained herein.   The information
 * in  this document is provided  "as is"  without warranty of any kind
 * and is subject  to  change  without  notice.   The warranties for HP
 * products are set forth in the express  limited  warranty  statements
 * accompanying such products.   Nothing herein should be construed  as
 * constituting an additional warranty.
 *
 * ++
 * FACILITY:
 *
 *    EXAMPLES
 *      
 * ABSTRACT:
 *
 *    This is an example of a TCP/IP IPv4 server using  4.x BSD
 *    socket Application Programming Interface (API) to  handle
 *    network I/O operations.
 *
 *    Refer to 'Build, Configuration, and Run Instructions' for
 *    details on how to build, configure, and run this program.
 *
 * ENVIRONMENT:
 *
 *    OpenVMS Alpha/VAX V7.1
 *    TCP/IP Services V5.0 or higher
 *
 * AUTHOR:
 *
 *    TCPIP Development Group,  CREATION DATE: 23-May-1989
 *
 * --
 */

	/* Build, Configuration, and Run Instructions */

/*
 *  BUILD INSTRUCTIONS:
 *
 *    To build this example program use commands of the form,
 *
 *    using the "C" compiler:
 *
 *	$ cc/prefix=all TCPIP$TCP_SERVER_SOCK.C
 *      $ link TCPIP$TCP_SERVER_SOCK
 *
 *
 * CONFIGURATION INSTRUCTIONS:
 *
 *    No special configuration required.
 *
 *
 * RUN INSTRUCTIONS:
 *
 *    To run this example program:
 *
 *    1) Start this server program as shown below:
 *
 *	 $ run tcpip$tcp_server_sock
 *	 Waiting for a client connection on port: m
 *
 *    2) After the server program blocks, start the client program,
 *       entering the server host as shown below:
 *
 *	 $ run tcpip$tcp_client_sock
 *	 Enter remote host:
 *
 *	 Note: You can specify a server host by using either an IPv4
 *	       address in dotted-decimal notation (e.g. 16.20.10.56)
 *	       or a host domain name (e.g. serverhost.hp.com).
 *
 *    3) The server program then displays client connection information
 *       and client data as shown below:
 *
 *	 Accepted connection from host: a.b.c.d, port: n
 *	 Data sent: Hello, world!
 *
 *    You can enter "ctrl/z" at any user prompt to terminate program
 *    execution.
 *    
 */


/*
 * INCLUDE FILES:
 */

#include <in.h>			    /* define internet related constants,   */
				    /* functions, and structures	    */
#include <inet.h>		    /* define network address info	    */

#include <netdb.h>		    /* define network database library info */

#include <socket.h>		    /* define BSD 4.x socket api	    */
#include <stdio.h>		    /* define standard i/o functions	    */
#include <stdlib.h>		    /* define standard library functions    */
#include <string.h>		    /* define string handling functions	    */

#include <unixio.h>		    /* define unix i/o			    */


/*
 * NAMED CONSTANTS:
 */

#define	SERV_BACKLOG	1		/* server backlog		    */
#define	SERV_PORTNUM	12345		/* server port number		    */


/*
 * FORWARD REFERENCES:
 */

int  main( void );			/* server main			    */

	/* Server Main */

/*
 * FUNCTIONAL DESCRIPTION:
 *
 *    This is the server's main-line code. It handles all the tasks of the
 *    server including: socket creation, accepting and/or rejecting client
 *    connections, writing client connection data,  and terminating client
 *    connections.
 *
 *    This example program implements a typical TCP IPv4 server using  the
 *    BSD socket API to handle network i/o operations as shown below:
 *
 *	1) To create a socket:
 *
 *	   socket()
 *
 *	2) To set REUSEADDR socket option:
 *
 *	   setsockopt()
 *
 *	3) To bind internet address and port number to a socket:
 *
 *	   bind()
 *
 *	4) To set an active socket to a passive (listen) socket:
 *
 *	   listen()
 *
 *	5) To accept a connection request:
 *
 *	   accept()
 *
 *	6) To transfer data:
 *
 *	   send()
 *
 *	7) To shutdown a socket (both directions):
 *
 *	   shutdown()
 *
 *	8) To close a socket:
 *
 *	   close()
 *
 *    This function is invoked by the DCL "RUN" command (see below);  the
 *    function's  completion  status is interpreted by DCL and if needed,
 *    an error message is displayed.
 *
 * SYNOPSIS:
 *
 *    int main( void )
 *
 * FORMAL PARAMETERS:
 *
 *    ** None **
 *
 * IMPLICIT INPUTS:
 *
 *    ** None **
 *
 * IMPLICIT OUTPUTS:
 *
 *    ** None **
 *
 * FUNCTION VALUE:
 *
 *    completion status
 *
 * SIDE EFFECTS:
 *
 *    ** None **
 *
 */ 

int
main( void )
{
    int	optval = 1;			/* SO_REUSEADDR'S option value (on) */

    int conn_sockfd;			/* connection socket descriptor	    */
    int listen_sockfd;			/* listen socket descriptor	    */

    unsigned int client_addrlen;	/* returned length of client socket */
					/* address structure		    */
    struct sockaddr_in client_addr;	/* client socket address structure  */
    struct sockaddr_in serv_addr;	/* server socket address structure  */

    char buf[] = "Hello, world!";	/* server data buffer		    */

    /*
     * init client's socket address structure
     */

    memset( &client_addr, 0, sizeof(client_addr) );

    /*
     * init server's socket address structure
     */

    memset( &serv_addr, 0, sizeof(serv_addr) );
    serv_addr.sin_family      = AF_INET;
    serv_addr.sin_port	      = htons( SERV_PORTNUM );
    serv_addr.sin_addr.s_addr = INADDR_ANY;

    /*
     * create a listen socket
     */

    if ( (listen_sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
	{
	perror( "Failed to create socket" );
	exit( EXIT_FAILURE );
	}

    /*
     * bind server's internet address and port number to listen socket
     */

    if ( setsockopt(listen_sockfd,
		    SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0 )
	{
	perror( "Failed to set socket option" );
	exit( EXIT_FAILURE );
	}

    if ( bind(listen_sockfd,
	      (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0 )
	{
	perror( "Failed to bind socket" );
	exit( EXIT_FAILURE );
	}

    /*
     * set listen socket as a passive socket
     */

    if ( listen(listen_sockfd, SERV_BACKLOG) < 0 )
	{
	perror( "Failed to set socket passive" );
	exit( EXIT_FAILURE );
	}

    /*
     * accept connection from a client
     */

    printf( "Waiting for a client connection on port: %d\n", 
	    ntohs(serv_addr.sin_port)
	  );

    client_addrlen = sizeof(client_addr);

    conn_sockfd = accept( listen_sockfd,
			  (struct sockaddr *) &client_addr,
			  &client_addrlen
			);
    if ( conn_sockfd < 0 )
	{
	perror( "Failed to accept client connection" );
	exit( EXIT_FAILURE );
	}

    printf( "Accepted connection from host: %s, port: %d\n",
	    inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port)
	  );

    /*
     * connection established with a client;
     * now attempt to write on this connection
     */

    if ( send(conn_sockfd, buf, sizeof(buf), 0) < 0 )
	{
	perror( "Failed to write data to client connection" );
	exit( EXIT_FAILURE );
	}

    printf( "Data sent: %s\n", buf );	   /* output server's data buffer  */

    /*
     * shutdown connection socket (both directions)
     */

    if ( shutdown(conn_sockfd, 2) < 0 )
	{
	perror( "Failed to shutdown client connection" );
	exit( EXIT_FAILURE );
	}

    /*
     * close connection socket
     */

    if ( close(conn_sockfd) < 0 )
	{
	perror( "Failed to close socket" );
	exit( EXIT_FAILURE );
	}

    /*
     * close listen socket
     */

    if ( close(listen_sockfd) < 0 )
	{
	perror( "Failed to close socket" );
	exit( EXIT_FAILURE );
	}

    exit( EXIT_SUCCESS );
}