Compaq TCP/IP Services for OpenVMS
Sockets API and System Services Programming


Previous Contents Index

E.4.2 UDP Server

Example E-10 shows how a typical UDP IPv4 server uses $QIO system services to handle the tasks of creating a socket, binding a socket to the server's internet address and port, and reading client data.

Example E-10 UDP Server (System Services)

 
#pragma module  tcpip$udp_server_qio                    \
                "V5.1-00" 
/* 
 * Copyright 2000 Compaq Computer Corporation 
 * 
 * COMPAQ Registered in U.S. Patent and Trademark Office. 
 * 
 * Confidential computer software.  Valid license from  Compaq 
 * or  authorized sublicensor 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. 
 * 
 * ++ 
 * FACILITY: 
 * 
 *    EXAMPLES 
 *      
 * ABSTRACT: 
 * 
 *    This is an example of a UDP/IP IPv4 server using  OpenVMS 
 *    QIO system services 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 DEC "C" compiler: 
 * 
 *      $ cc/prefix=all TCPIP$UDP_SERVER_QIO.C 
 *      $ link TCPIP$UDP_SERVER_QIO 
 *    
 *    using the DEC "C++" compiler: 
 *    
 *      $ cxx/prefix=all/define=VMS TCPIP$UDP_SERVER_QIO.C 
 *      $ link TCPIP$UDP_SERVER_QIO 
 * 
 * 
 * CONFIGURATION INSTRUCTIONS: 
 * 
 *    No special configuration required. 
 * 
 *    
 * RUN INSTRUCTIONS: 
 * 
 *    To run this example program: 
 * 
 *    1) Start this server program as shown below: 
 * 
 *       $ run tcpip$udp_server_qio 
 *       Waiting for a client datagram on port: m 
 * 
 *    2) After the server program blocks, start the client program, 
 *       entering the server host as shown below: 
 * 
 *       $ run tcpip$udp_client_qio 
 *       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.compaq.com). 
 * 
 *    3) The server program then displays client address information 
 *       and client data as show below: 
 * 
 *       Received a datagram from host: a.b.c.d, port: n 
 *       Data received: Hello, world! 
 * 
 *    You can enter "ctrl/z" at any user prompt to terminate program 
 *    execution. 
 * 
 */ 
 
/* 
 * INCLUDE FILES: 
 */ 
 
#include <descrip.h>                /* define OpenVMS descriptors           */ 
 
#include <efndef.h>                 /* define 'EFN$C_ENF' event flag        */ 
 
#include <in.h>                     /* define internet related constants,   */ 
                                    /* functions, and structures            */ 
#include <inet.h>                   /* define network address info          */ 
#include <iodef.h>                  /* define i/o function codes            */ 
 
#include <netdb.h>                  /* define network database library info */ 
 
#include <ssdef.h>                  /* define system service status codes   */ 
#include <starlet.h>                /* define system service calls          */ 
#include <stdio.h>                  /* define standard i/o functions        */ 
#include <stdlib.h>                 /* define standard library functions    */ 
#include <string.h>                 /* define string handling functions     */ 
#include <stsdef.h>                 /* define condition value fields        */ 
 
#include <tcpip$inetdef.h>          /* define tcp/ip network constants,     */ 
                                    /* structures, and functions            */ 
 
 
/* 
 * NAMED CONSTANTS: 
 */ 
 
#define SERV_PORTNUM    12345           /* server port number               */ 
 
 
/* 
 * STRUCTURE DEFINITIONS: 
 */ 
 
struct iosb 
    {                                   /* i/o status block                 */ 
    unsigned short status;              /* i/o completion status            */ 
    unsigned short bytcnt;              /* bytes transferred if read/write  */ 
    void *details;                      /* address of buffer or parameter   */ 
    }; 
 
struct itemlst_2 
    {                                   /* item-list 2 descriptor/element   */ 
    unsigned short length;              /* length                           */ 
    unsigned short type;                /* parameter type                   */ 
    void *address;                      /* address of item list             */ 
    }; 
 
struct itemlst_3 
    {                                   /* item-list 3 descriptor/element   */ 
    unsigned short length;              /* length                           */ 
    unsigned short type;                /* parameter type                   */ 
    void *address;                      /* address of item list             */ 
    unsigned int *retlen;               /* address of returned length       */ 
    }; 
 
struct sockchar 
    {                                   /* socket characteristics buffer    */ 
    unsigned short prot;                /* protocol                         */ 
    unsigned char type;                 /* type                             */ 
    unsigned char af;                   /* address format                   */ 
    }; 
 
 
/* 
 * FORWARD REFERENCES: 
 */ 
 
int  main( void );                      /* client main                      */ 
        /* Server Main */ 
 
/* 
 * FUNCTIONAL DESCRIPTION: 
 * 
 *    This is the server's main-line code. It handles all the tasks of the 
 *    server including: socket creation, binding a socket to the  server's 
 *    internet address and port, and reading client data. 
 * 
 *    This example program implements a typical UDP IPv4 server using  QIO 
 *    system services to handle network i/o operations as shown below: 
 * 
 *      1) To create a socket and set REUSEADDR option: 
 * 
 *         sys$assign() and sys$qiow(IO$_SETMODE) 
 * 
 *      2) To bind internet address and port number to a socket: 
 * 
 *         sys$qiow(IO$_SETMODE) 
 * 
 *      3) To transfer data: 
 * 
 *         sys$qiow(IO$_READVBLK) 
 * 
 *      4) To close and delete a socket: 
 * 
 *         sys$qiow(IO$_DEACCESS) and sys$dassgn() 
 * 
 *    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 one = 1;                        /* reuseaddr option value           */ 
 
    char buf[512];                      /* server data buffer               */ 
    int  buflen = sizeof( buf );        /* length of server data buffer     */ 
 
    struct iosb iosb;                   /* i/o status block                 */ 
 
    unsigned int status;                /* system service return status     */ 
 
    unsigned short inet_channel;        /* inet device i/o channel          */ 
    struct sockchar udp_sockchar;       /* socket char buffer               */ 
 
    unsigned int client_retlen;         /* returned length of client socket */ 
                                        /* address structure                */ 
    struct sockaddr_in client_addr;     /* client socket address structure  */ 
    struct itemlst_3 client_itemlst;    /* client item-list 3 descriptor    */ 
 
    struct sockaddr_in serv_addr;       /* server socket address structure  */ 
    struct itemlst_2 serv_itemlst;      /* server item-list 2 descriptor    */ 
 
    struct itemlst_2 sockopt_itemlst;   /* sockopt item-list 2 descriptor   */ 
    struct itemlst_2 reuseaddr_itemlst; /* reuseaddr item-list 2 element    */ 
 
    $DESCRIPTOR( inet_device,           /* string descriptor with logical   */ 
                 "TCPIP$DEVICE" );      /* name of internet pseudodevice    */ 
 
    /* 
     * init udp socket characteristics buffer 
     */ 
 
    udp_sockchar.prot = TCPIP$C_UDP; 
    udp_sockchar.type = TCPIP$C_DGRAM; 
    udp_sockchar.af   = TCPIP$C_AF_INET; 
 
    /* 
     * init reuseaddr's item-list element 
     */ 
 
    reuseaddr_itemlst.length  = sizeof( one ); 
    reuseaddr_itemlst.type    = TCPIP$C_REUSEADDR; 
    reuseaddr_itemlst.address = &one; 
 
    /* 
     * init sockopt's item-list descriptor 
     */ 
 
    sockopt_itemlst.length  = sizeof( reuseaddr_itemlst ); 
    sockopt_itemlst.type    = TCPIP$C_SOCKOPT; 
    sockopt_itemlst.address = &reuseaddr_itemlst; 
 
    /* 
     * init client's item-list descriptor 
     */ 
 
    memset( &client_itemlst, 0, sizeof(client_itemlst) ); 
    client_itemlst.length  = sizeof( client_addr ); 
    client_itemlst.address = &client_addr; 
    client_itemlst.retlen  = &client_retlen; 
 
    /* 
     * init client's socket address structure 
     */ 
 
    memset( &client_addr, 0, sizeof(client_addr) ); 
 
    /* 
     * init server's item-list descriptor 
     */ 
 
    serv_itemlst.length  = sizeof( serv_addr ); 
    serv_itemlst.type    = TCPIP$C_SOCK_NAME; 
    serv_itemlst.address = &serv_addr; 
 
    /* 
     * init server's socket address structure 
     */ 
 
    memset( &serv_addr, 0, sizeof(serv_addr) ); 
    serv_addr.sin_family      = TCPIP$C_AF_INET; 
    serv_addr.sin_port        = htons( SERV_PORTNUM ); 
    serv_addr.sin_addr.s_addr = TCPIP$C_INADDR_ANY; 
 
    /* 
     * assign device socket 
     */ 
 
    status = sys$assign( &inet_device,      /* device name                  */ 
                         &inet_channel,     /* i/o channel                  */ 
                         0,                 /* access mode                  */ 
                         0                  /* not used                     */ 
                       ); 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to assign i/o channel to TCPIP device\n" ); 
        exit( status ); 
        } 
 
    /* 
     * create udp socket 
     */ 
 
    status = sys$qiow( EFN$C_ENF,           /* event flag                   */ 
                       inet_channel,        /* i/o channel                  */ 
                       IO$_SETMODE,         /* i/o function code            */ 
                       &iosb,               /* i/o status block             */ 
                       0,                   /* ast service routine          */ 
                       0,                   /* ast parameter                */ 
                       &udp_sockchar,       /* p1 - socket char buffer      */ 
                       0,                   /* p2                           */ 
                       0,                   /* p3                           */ 
                       0,                   /* p4                           */ 
                       &sockopt_itemlst,    /* p5 - socket options          */ 
                       0                    /* p6                           */ 
                     ); 
 
    if ( status & STS$M_SUCCESS ) 
        status = iosb.status; 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to create socket\n" ); 
        exit( status ); 
        } 
 
    /* 
     * bind server's internet address and port number to socket 
     */ 
 
    status = sys$qiow( EFN$C_ENF,           /* event flag                   */ 
                       inet_channel,        /* i/o channel                  */ 
                       IO$_SETMODE,         /* i/o function code            */ 
                       &iosb,               /* i/o status block             */ 
                       0,                   /* ast service routine          */ 
                       0,                   /* ast parameter                */ 
                       0,                   /* p1                           */ 
                       0,                   /* p2                           */ 
                       &serv_itemlst,       /* p3 - local socket name       */ 
                       0,                   /* p4                           */ 
                       0,                   /* p5                           */ 
                       0                    /* p6                           */ 
                     ); 
 
    if ( status & STS$M_SUCCESS ) 
        status = iosb.status; 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to bind socket\n" ); 
        exit( status ); 
        } 
 
    /* 
     * read datagram from client 
     */ 
 
    printf( "Waiting for a client datagram on port: %d\n", 
            ntohs(serv_addr.sin_port) 
          ); 
 
    status = sys$qiow( EFN$C_ENF,           /* event flag                   */ 
                       inet_channel,        /* i/o channel                  */ 
                       IO$_READVBLK,        /* i/o function code            */ 
                       &iosb,               /* i/o status block             */ 
                       0,                   /* ast service routine          */ 
                       0,                   /* ast parameter                */ 
                       buf,                 /* p1 - buffer address          */ 
                       buflen,              /* p2 - buffer length           */ 
                       &client_itemlst,     /* p3 - remote socket name      */ 
                       0,                   /* p4                           */ 
                       0,                   /* p5                           */ 
                       0                    /* p6                           */ 
                     ); 
 
    if ( status & STS$M_SUCCESS ) 
        status = iosb.status; 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to read datagram from client\n" ); 
        exit( status ); 
        } 
 
 
    printf( "Received a datagram from host: %s, port: %d\n", 
            inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port) 
          ); 
    printf( "Data received: %s\n", buf );   /* output client's data         */ 
 
    /* 
     * close udp socket 
     */ 
 
    status = sys$qiow( EFN$C_ENF,           /* event flag                   */ 
                       inet_channel,        /* i/o channel                  */ 
                       IO$_DEACCESS,        /* i/o function code            */ 
                       &iosb,               /* i/o status block             */ 
                       0,                   /* ast service routine          */ 
                       0,                   /* ast parameter                */ 
                       0,                   /* p1                           */ 
                       0,                   /* p2                           */ 
                       0,                   /* p3                           */ 
                       0,                   /* p4                           */ 
                       0,                   /* p5                           */ 
                       0                    /* p6                           */ 
                     ); 
 
    if ( status & STS$M_SUCCESS ) 
        status = iosb.status; 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to close socket\n" ); 
        exit( status ); 
        } 
 
    /* 
     * deassign device socket 
     */ 
 
    status = sys$dassgn( inet_channel ); 
 
    if ( !(status & STS$M_SUCCESS) ) 
        { 
        printf( "Failed to deassign i/o channel to TCPIP device\n" ); 
        exit( status ); 
        } 
 
    exit( EXIT_SUCCESS ); 
} 


Index Contents