#pragma	module	tcpip$udp_client_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 UDP/IP IPv4 client 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$UDP_CLIENT_SOCK.C
 *      $ link TCPIP$UDP_CLIENT_SOCK
 *
 *
 * CONFIGURATION INSTRUCTIONS:
 *
 *    No special configuration required.
 *
 *    
 * RUN INSTRUCTIONS:
 *
 *    To run this example program:
 *
 *    1) Start the client's server program as shown below:
 *
 *	 $ run tcpip$udp_server_sock
 *	 Waiting for a client datagram on port: m
 *
 *    2) After the server program blocks, start this client program,
 *       entering the server host as shown below:
 *
 *	 $ run tcpip$udp_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 client program then displays server address information
 *	 and server data as show below:
 *
 *	 Sent a datagram to 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	BUFSZ		1024		/* user input buffer size	    */
#define	SERV_PORTNUM	12345		/* server port number		    */


/*
 * FORWARD REFERENCES:
 */

int  main( void );			/* client main			    */
void get_serv_addr( void * );		/* get server host address	    */

	/* Client Main */

/*
 * FUNCTIONAL DESCRIPTION:
 *
 *    This is the client's main-line code. It handles all the tasks of the
 *    client including: socket creation, writing server data, and deleting
 *    the socket.
 *
 *    This example program implements a typical UDP IPv4 client using  the
 *    BSD socket API to handle network i/o operations as shown below:
 *
 *	1) To create a socket:
 *
 *	   socket()
 *
 *	2) To transfer data:
 *
 *	   sendto()
 *
 *	3) 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 sockfd;				/* udp socket descriptor	    */

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

    struct sockaddr_in serv_addr;	/* server socket address structure  */

    /*
     * 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 );
    get_serv_addr( &serv_addr.sin_addr );

    /*
     * create udp socket
     */

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

    /*
     * write datagram to server
     */

    if ( sendto(sockfd, buf, sizeof(buf), 0,
		(struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0 )
	{
	perror( "Failed to write datagram to server" );
	exit( EXIT_FAILURE );
	}

    printf( "Sent a datagram to host: %s, port: %d\n",
	    inet_ntoa(serv_addr.sin_addr), ntohs(serv_addr.sin_port)
	  );
    printf( "Data sent: %s\n", buf );	    /* output data buffer	    */

    /*
     * close udp socket
     */

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

    exit( EXIT_SUCCESS );
}

	/* Get Server Host Address */

/*
 * FUNCTIONAL DESCRIPTION:
 *
 *    This function gets the server host's address from the user and then
 *    stores it in the server's socket address structure.  Note that  the
 *    user can specify a server host by using either an IPv4  address  in
 *    dotted-decimal notation (e.g. 16.20.10.126) or a host  domain  name
 *    (e.g. serverhost.hp.com).
 *
 *    Enter "ctrl/z" to terminate program execution.
 *
 * SYNOPSIS:
 *
 *    void get_serv_addr( void *addrptr )
 *
 * FORMAL PARAMETERS:
 *
 *    addrptr  -  pointer to socket address structure's 'sin_addr' field
 *		  to store the specified network address
 *
 * IMPLICIT INPUTS:
 *
 *    ** None **
 *
 * IMPLICIT OUTPUTS:
 *
 *    ** None **
 *
 * FUNCTION VALUE:
 *
 *    ** None **
 *
 * SIDE EFFECTS:
 *
 *    Program execution is terminated if unable to read user's input.
 *
 */ 

void
get_serv_addr( void *addrptr )
{
    char buf[BUFSZ];
    struct in_addr val;
    struct hostent *host;

    while ( TRUE )
	{
	printf( "Enter remote host: " );

	if ( fgets(buf, sizeof(buf), stdin) == NULL )
	    {
	    printf( "Failed to read user input\n" );
	    exit( EXIT_FAILURE );
	    }

	buf[strlen(buf)-1] = 0;

	val.s_addr = inet_addr( buf );

	if ( val.s_addr != INADDR_NONE )
	    {
	    memcpy( addrptr, &val, sizeof(struct in_addr) );
	    break;
	    }

	if ( (host = gethostbyname(buf)) )
	    {
	    memcpy( addrptr, host->h_addr, sizeof(struct in_addr) );
	    break;
	    }
	}
}