DEC C
Run-Time Library Reference Manual for OpenVMS Systems
Previous Contents Index

A.9 Programming Examples

This section provides DEC C socket communications programming examples.

Example A-1 is an example of a TCP/IP Server.

Example A-1 TCP/IP Server 

/*==================================================================== 
* 
*                          Copyright (C) 1989 by 
*              Digital Equipment Corporation, Maynard, Mass. 
* 
* This software is furnished under a license and may be used and  copied 
* only  in  accordance  with  the  terms  of  such  license and with the 
* inclusion of the above copyright notice.  This software or  any  other 
* copies  thereof may not be provided or otherwise made available to any 
* other person.  No title to and ownership of  the  software  is  hereby 
* transferred. 
* 
* The information in this software is subject to change  without  notice 
* and  should  not  be  construed  as  a commitment by Digital Equipment 
* Corporation. 
* 
* Digital assumes no responsibility for the use or  reliability  of  its 
* software on equipment that is not supplied by Digital. 
* 
* 
* 
*  FACILITY: 
*        INSTALL 
*      
* 
*  ABSTRACT: 
*        This is an example of a TCP/IP server using the IPC 
*        socket interface. 
*      
* 
*  ENVIRONMENT: 
*        UCX V1.2 or higher, VMS V5.2 or higher 
* 
*        This example is portable to ULTRIX. The include 
*        files are conditionally defined for both systems, and 
*        "perror" is used for error reporting. 
* 
*        To link in DEC C on OpenVMS Systems, you must have the following 
*        entries in your .opt file: 
*           sys$library:ucx$ipc.olb/lib 
*           sys$share:vaxcrtl.exe/share 
* 
*  AUTHORS: 
*        UCX Developer        
* 
*  CREATION DATE: May 23, 1989 
* 
*  MODIFICATION HISTORY: 
* 
*/ 
 
 
/* 
* 
*  INCLUDE FILES 
* 
*/ 
 
#ifdef __VMS 
#include  <errno.h> 
#include  <stdio.h> 
#include  <socket.h> 
#include  <in.h> 
#include  <netdb.h>                /* Change hostent to comply with BSD 4.3. */ 
#include  <inet.h> 
#include  <ucx$inetdef.h>          /* INET symbol definitions. */ 
#else 
#include <errno.h> 
#include <sys/types.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h> 
#include <arpa/inet.h> 
#include <sys/uio.h> 
#endif 
 
 
/* 
* Functional Description 
* 
*        This example creates a socket of type SOCK_STREAM (TCP), 
*        binds and listens on the socket, receives a message, 
*        and closes the connection.        
*        Error messages are printed to the screen. 
* 
*        IPC calls used: 
*        accept 
*        bind 
*        close 
*        gethostbyname 
*        listen 
*        recv        
*        shutdown 
*        socket        
* 
* 
* Formal Parameters 
*        The server program expects one parameter: 
*        portnumber ... port number where it will listen 
* 
* 
* Routine Value 
* 
*        Status        
*/ 
 
/*--------------------------------------------------------------------*/ 
main(argc,argv) 
int        argc; 
char       **argv; 
{ 
 
        int     sock_2, sock_3;                 /* sockets */ 
static  char    message[BUFSIZ]; 
static struct   sockaddr_in sock2_name;         /* Address struct for socket2.*/ 
static struct   sockaddr_in retsock2_name;      /* Address struct for socket2.*/ 
        struct  hostent hostentstruct;          /* Storage for hostent data.  */ 
        struct  hostent *hostentptr;            /* Pointer to hostent data.   */ 
static  char    hostname[256];                  /* Name of local host.        */ 
        int     flag; 
        int     retval;                         /* Helpful for debugging. */ 
        int     namelength;                        
 
 
        /*        
         * Check input parameters. 
         */ 
        if (argc != 2 ) 
                { 
                printf("Usage: server portnumber.\n"); 
                exit(); 
                } 
 
        /* 
         * Open socket 2: AF_INET, SOCK_STREAM. 
         */ 
        if ((sock_2 = socket (AF_INET, SOCK_STREAM, 0)) == -1) 
                { 
                perror( "socket"); 
                exit(); 
                } 
 
        /* 
         * Get the host local name. 
         */ 
        retval = gethostname(hostname,sizeof hostname); 
        if (retval) 
                { 
                perror ("gethostname"); 
                cleanup (1, sock_2, 0); 
                } 
 
        /* 
         * Get pointer to network data structure for socket 2. 
         */ 
        if ((hostentptr = gethostbyname (hostname)) == NULL) 
                { 
                perror( "gethostbyname"); 
                cleanup(1, sock_2, 0); 
                } 
 
        /* 
         * Copy hostent data to safe storage. 
         */ 
        hostentstruct = *hostentptr; 
 
        /* 
         * Fill in the name & address structure for socket 2. 
         */ 
        sock2_name.sin_family = hostentstruct.h_addrtype; 
        sock2_name.sin_port = htons(atoi(argv[1])); 
        sock2_name.sin_addr = * ((struct in_addr *) hostentstruct.h_addr); 
 
        /* 
         * Bind name to socket 2. 
         */ 
        retval = bind (sock_2, &sock2_name, sizeof sock2_name); 
        if (retval) 
                { 
                perror("bind"); 
                cleanup(1, sock_2, 0); 
                } 
 
        /* 
         * Listen on socket 2 for connections. 
         */ 
        retval = listen (sock_2, 5); 
        if (retval) 
                { 
                perror("listen"); 
                cleanup(1, sock_2, 0); 
                } 
 
        /* 
         * Accept connection from socket 2:             
         * accepted connection will be on socket 3. 
         */ 
        namelength = sizeof (sock2_name); 
        sock_3 = accept (sock_2, &sock2_name, &namelength); 
        if (sock_3 == -1) 
                { 
                perror ("accept"); 
                cleanup( 2, sock_2, sock_3); 
                } 
 
        /* 
         * Receive message from socket 1. 
         */ 
        flag = 0;        /* maybe 0 or MSG_OOB or MSG_PEEK */ 
 
        retval = recv(sock_3, message ,sizeof (message), flag); 
        if (retval == -1) 
                { 
                perror ("receive"); 
                cleanup( 2, sock_2, sock_3); 
                } 
        else 
                printf (" %s\n", message); 
 
        /* 
         * Call cleanup to shutdown and close sockets. 
         */ 
        cleanup(2, sock_2, sock_3); 
 
 } /* end main */ 
 
/*-----------------------------------------------------------*/ 
 
cleanup(how_many, sock1, sock2) 
int        how_many; 
int        sock1, sock2; 
        
{ 
        int        retval; 
 
        /* 
         * Shutdown and close sock1 completely. 
         */ 
        retval = shutdown(sock1,2); 
        if (retval == -1) 
                perror ("shutdown"); 
 
        retval = close (sock1); 
        if (retval) 
                perror ("close"); 
 
 
        /* 
         * If given, shutdown and close sock2. 
         */ 
        if (how_many == 2) 
        { 
                retval = shutdown(sock2,2); 
                if (retval == -1) 
                        perror ("shutdown"); 
 
                retval = close (sock2); 
                if (retval) 
                        perror ("close"); 
        } 
 
        exit(); 
 
} /* end cleanup*/

Example A-2 is an example of a TCP/IP Client.

Example A-2 TCP/IP Client 

/*==================================================================== 
* 
*                          Copyright (C) 1989 by 
*              Digital Equipment Corporation, Maynard, Mass. 
* 
* This software is furnished under a license and may be used and  copied 
* only  in  accordance  with  the  terms  of  such  license and with the 
* inclusion of the above copyright notice.  This software or  any  other 
* copies  thereof may not be provided or otherwise made available to any 
* other person.  No title to and ownership of  the  software  is  hereby 
* transferred. 
* 
* The information in this software is subject to change  without  notice 
* and  should  not  be  construed  as  a commitment by Digital Equipment 
* Corporation. 
* 
* Digital assumes no responsibility for the use or  reliability  of  its 
* software on equipment that is not supplied by Digital. 
* 
* 
* 
*  FACILITY: 
*        INSTALL 
*      
* 
*  ABSTRACT: 
*        This is an example of a TCP/IP client using the IPC 
*        socket interface. 
*      
* 
*  ENVIRONMENT: 
*        UCX V1.2 or higher, VMS V5.2 or higher  
* 
*        This example is portable to ULTRIX. The include 
*        files are conditionally defined for both systems, and 
*        "perror" is used for error reporting. 
* 
*        To link in DEC C on OpenVMS Systems, you must have the following 
*        entries in your .opt file: 
*           sys$library:ucx$ipc.olb/lib 
*           sys$share:vaxcrtl.exe/share 
* 
*  AUTHORS: 
*        UCX Developer        
* 
*  CREATION DATE: May 23, 1989 
* 
*  MODIFICATION HISTORY: 
* 
*/ 
 
 
/* 
* 
*  INCLUDE FILES 
* 
*/ 
 
#ifdef __VMS 
#include  <errno.h> 
#include  <stdio.h> 
#include  <socket.h> 
#include  <in.h> 
#include  <netdb.h>              /* Change hostent to comply with BSD 4.3. */ 
#include  <inet.h> 
#include  <ucx$inetdef.h>        /* INET symbol definitions. */ 
#else 
#include <errno.h> 
#include <sys/types.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h> 
#include <arpa/inet.h> 
#include <sys/uio.h> 
#endif 
 
 
/* 
* 
*   MACRO DEFINITIONS 
* 
*/ 
 
#ifndef vms 
#define TRUE 1 
#define FALSE 0 
#endif 
 
/* 
* Functional Description 
* 
*        This example creates a socket of type SOCK_STREAM (TCP), 
*        initiates a connection to the remote host, sends 
*        a message to the remote host, and closes the connection.        
*        Error messages are printed to the screen. 
* 
*        IPC calls used: 
*        close 
*        connect 
*        gethostbyname 
*        send 
*        shutdown 
*        socket        
* 
* 
* Formal Parameters 
*        The client program expects two parameters: 
*        hostname ... name of remote host 
*        portnumber ... port where remote host(server) is listening 
* 
* 
* Routine Value 
* 
*        Status        
*/ 
 
/*--------------------------------------------------------------------*/ 
main(argc,argv) 
int        argc; 
char       **argv; 
{ 
 
        int     sock_1;                         /* socket */ 
static  char    message[] = "Hi there."; 
static  struct  sockaddr_in sock2_name;         /* Address struct for socket2.*/ 
        struct  hostent         hostentstruct;  /* Storage for hostent data.  */ 
        struct  hostent         *hostentptr;    /* Pointer to hostent data.   */ 
        static  char            hostname[256];  /* Name of local host.        */ 
        int     flag; 
        int     retval;                         /* Helpful for debugging.     */ 
        int     shut = FALSE;                   /* Flag to cleanup.           */ 
 
 
        /* 
         * Check input parameters. 
         */ 
        if (argc != 3 ) 
                { 
                printf("Usage: client hostname portnumber.\n"); 
                exit(); 
                } 
 
 
        /* 
         * Open socket 1: AF_INET, SOCK_STREAM. 
         */ 
        if ((sock_1 = socket (AF_INET, SOCK_STREAM, 0)) == -1) 
                { 
                perror( "socket"); 
                exit(); 
                } 
 
 
        /* 
         *Get pointer to network data structure for socket 2 (remote host). 
         */ 
        if ((hostentptr = gethostbyname (argv[1])) == NULL) 
                { 
                perror( "gethostbyname"); 
                cleanup(shut, sock_1); 
                } 
                
 
 
        /* 
         * Copy hostent data to safe storage. 
         */ 
        hostentstruct = *hostentptr; 
 
 
        /* 
         * Fill in the name & address structure for socket 2. 
         */ 
        sock2_name.sin_family = hostentstruct.h_addrtype; 
        sock2_name.sin_port = htons(atoi(argv[2])); 
        sock2_name.sin_addr = * ((struct in_addr *) hostentstruct.h_addr); 
 
 
        /* 
         * Connect socket 1 to sock2_name. 
         */ 
        retval = connect(sock_1, &sock2_name, sizeof (sock2_name)); 
        if (retval) 
                { 
                perror("connect"); 
                cleanup(shut, sock_1); 
                } 
 
 
        /* 
         * Send message to socket 2. 
         */ 
        flag = 0;        /* maybe 0 or MSG_OOB */ 
        retval = send(sock_1, message ,sizeof (message), flag); 
        if (retval < 0) 
                { 
                perror ("send"); 
                shut = TRUE;        
                } 
 
 
        /* 
         * Call cleanup to shutdown and close socket. 
         */ 
        cleanup(shut, sock_1); 
 
 } /* end main */ 
 
/*-----------------------------------------------------------*/ 
 
cleanup(shut, socket) 
int        shut; 
int        socket; 
        
{ 
        int        retval; 
 
        /* 
         * Shutdown socket completely -- only if it was connected. 
         */ 
        if (shut) { 
                retval = shutdown(socket,2); 
                if (retval == -1) 
                        perror ("shutdown"); 
        } 
 
 
        /* 
         * Close socket. 
         */ 
        retval = close (socket); 
        if (retval) 
                perror ("close"); 
 
        exit(); 
 
 } /* end main */

Example A-3 is an example of a UDP/IP Server.

Example A-3 UDP/IP Server 

/*==================================================================== 
* 
*                          Copyright (C) 1989 by 
*              Digital Equipment Corporation, Maynard, Mass. 
* 
* This software is furnished under a license and may be used and  copied 
* only  in  accordance  with  the  terms  of  such  license and with the 
* inclusion of the above copyright notice.  This software or  any  other 
* copies  thereof may not be provided or otherwise made available to any 
* other person.  No title to and ownership of  the  software  is  hereby 
* transferred. 
* 
* The information in this software is subject to change  without  notice 
* and  should  not  be  construed  as  a commitment by Digital Equipment 
* Corporation. 
* 
* Digital assumes no responsibility for the use or  reliability  of  its 
* software on equipment that is not supplied by Digital. 
* 
* 
* 
*  FACILITY: 
*        INSTALL 
*      
* 
*  ABSTRACT: 
*        This is an example of a UDP/IP server using the IPC 
*        socket interface. 
*      
* 
*  ENVIRONMENT: 
*        UCX V1.2 or higher, VMS V5.2 or higher 
* 
*        This example is portable to ULTRIX. The include 
*        files are conditionally defined for both systems, and 
*        "perror" is used for error reporting. 
* 
*        To link in DEC C on OpenVMS Systems, you must have the following 
*        entries in your .opt file: 
*           sys$library:ucx$ipc.olb/lib 
*           sys$share:vaxcrtl.exe/share 
* 
*  AUTHORS: 
*        UCX Developer        
* 
*  CREATION DATE: May 23, 1989 
* 
*  MODIFICATION HISTORY: 
* 
*/ 
 
 
/* 
* 
*  INCLUDE FILES 
* 
*/ 
 
#ifdef __VMS 
#include  <errno.h> 
#include  <stdio.h> 
#include  <socket.h>               /* timeval declared here. */ 
#include  <in.h> 
#include  <netdb.h>                /* Change hostent to comply with BSD 4.3. */ 
#include  <inet.h> 
#include  <ucx$inetdef.h>          /* INET symbol definitions. */ 
#else 
#include <errno.h> 
#include <sys/types.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h> 
#include <arpa/inet.h> 
#include <sys/uio.h> 
#include <time.h>                 /* timeval declared here. */ 
#endif 
 
 
/* 
* Functional Description 
* 
*        This example creates a socket of type SOCK_DGRAM (UDP), binds 
*        it, and selects to receive a message on the socket. 
*        Error messages are printed to the screen. 
* 
*        IPC calls used: 
*        bind 
*        close 
*        gethostbyname 
*        recvfrom 
*        select 
*        shutdown 
*        socket        
* 
* 
* Formal Parameters 
*        The server program expects one parameter: 
*        portnumber ... port where it is listening 
* 
* 
* Routine Value 
* 
*        Status        
*/ 
 
/*--------------------------------------------------------------------*/ 
main(argc, argv) 
int        argc; 
char       **argv; 
{ 
 
        unsigned long rmask,wmask,emask; 
        int     sock_2;                       /* Socket2  descriptor.       */ 
        int     buflen,fromlen; 
        char    recvbuf[BUFSIZ]; 
static  struct  sockaddr_in sock1_name;       /* Address struct for socket1.*/ 
static  struct  sockaddr_in sock2_name;       /* Address struct for socket2.*/ 
        int     namelength; 
        struct  hostent hostentstruct;        /* Storage for hostent data.  */ 
        struct  hostent *hostentptr;          /* Pointer to hostent data.   */ 
        static  char hostname[256];           /* Name of local host.        */ 
        int     retval; 
        int     flag; 
        struct  timeval timeout;        
 
 
        /* 
         * Check input parameters. 
         */ 
        if (argc != 2 ) 
                { 
                printf("Usage: server portnumber.\n"); 
                exit(); 
                } 
 
 
        /* 
         * Open socket 2: AF_INET, SOCK_DGRAM. 
         */ 
        if ((sock_2 = socket (AF_INET, SOCK_DGRAM, 0)) == -1) 
                { 
                perror( "socket"); 
                exit(); 
                } 
 
 
        /* 
         * Get the local host name. 
         */ 
        retval = gethostname(hostname,sizeof hostname); 
        if (retval) 
                { 
                perror ("gethostname"); 
                cleanup(sock_2); 
                 } 
        
 
        /* 
         * Get pointer to network data structure for local host. 
         */ 
        if ((hostentptr = gethostbyname (hostname)) == NULL) 
                { 
                perror( "gethostbyname"); 
                cleanup(sock_2); 
                 } 
 
 
        /* 
         * Copy hostent data to safe storage. 
         */ 
        hostentstruct = *hostentptr; 
 
 
        /* 
         * Fill in the address structure for socket 2. 
         */ 
        sock2_name.sin_family = hostentstruct.h_addrtype; 
        sock2_name.sin_port = htons(atoi(argv[1])); 
        sock2_name.sin_addr = * ((struct in_addr *) hostentstruct.h_addr); 
 
 
        /* 
         * Bind name to socket 2. 
         */ 
        retval = bind (sock_2, &sock2_name, sizeof sock2_name); 
        if (retval)                       
                { 
                perror("bind"); 
                cleanup(sock_2); 
                 } 
 
 
        /* 
         * Select socket to receive message. 
         */ 
        emask = wmask = 0; 
        rmask = (1<<sock_2);  /* set read mask */ 
        timeout.tv_sec = 30; 
        timeout.tv_usec = 0; 
        
        retval = select(32,&rmask,&wmask,&emask, &timeout); 
        switch (retval) 
        { 
          case -1: 
                { 
                perror("select"); 
                cleanup(sock_2); 
                } 
          case 0: 
                { 
                printf("Select timed out with status 0.\n"); 
                cleanup(sock_2); 
                } 
          default: 
                if ((rmask & (1<<sock_2)) == 0) 
                        { 
                        printf("Select not reading on sock_2.\n"); 
                        cleanup(sock_2); 
                        } 
        } /*switch*/ 
 
 
 
        /* 
         * Recvfrom buffer - from sock1 on sock2. 
         */ 
        buflen = sizeof(recvbuf); 
        fromlen = sizeof(sock1_name); 
        flag = 0;        /* flag may be MSG_OOB and/or MSG_PEEK */ 
 
        retval = recvfrom(sock_2, recvbuf, buflen, flag, &sock1_name, &fromlen); 
        if (retval == -1) 
                perror("recvfrom"); 
           else 
                printf (" %s\n", recvbuf); 
 
        /* 
         * Call cleanup to shut down and close socket. 
         */ 
        cleanup(sock_2); 
 
 } /* end main */ 
 
/*-----------------------------------------------------------*/ 
 
cleanup(socket) 
int  socket; 
        
{ 
        int   retval; 
 
        /* 
         * Shut down socket  completely. 
         */ 
        retval = shutdown(socket,2); 
        if (retval == -1) 
                perror ("shutdown"); 
 
 
        /* 
         * Close socket. 
         */ 
        retval = close (socket); 
        if (retval) 
                perror ("close"); 
 
        exit(); 
 
 
} /* end cleanup */

Example A-4 is an example of a UDP/IP client.

Example A-4 UDP/IP Client 

/*==================================================================== 
* 
*                          Copyright (C) 1989 by 
*              Digital Equipment Corporation, Maynard, Mass. 
* 
* This software is furnished under a license and may be used and  copied 
* only  in  accordance  with  the  terms  of  such  license and with the 
* inclusion of the above copyright notice.  This software or  any  other 
* copies  thereof may not be provided or otherwise made available to any 
* other person.  No title to and ownership of  the  software  is  hereby 
* transferred. 
* 
* The information in this software is subject to change  without  notice 
* and  should  not  be  construed  as  a commitment by Digital Equipment 
* Corporation. 
* 
* Digital assumes no responsibility for the use or  reliability  of  its 
* software on equipment that is not supplied by Digital. 
* 
* 
* 
*  FACILITY: 
*        INSTALL 
*      
* 
*  ABSTRACT: 
*        This is an example of a UDP/IP client using the IPC 
*        socket interface. 
*      
* 
*  ENVIRONMENT: 
*        UCX V1.2 or higher, VMS V5.2 or higher 
* 
*        This example is portable to ULTRIX. The include 
*        files are conditionally defined for both systems, and 
*        "perror" is used for error reporting. 
* 
*        To link in DEC C on OpenVMS Systems, you must have the following 
*        entries in your .opt file: 
*           sys$library:ucx$ipc.olb/lib 
*           sys$share:vaxcrtl.exe/share 
* 
*  AUTHORS: 
*        UCX Developer        
* 
*  CREATION DATE: May 23, 1989 
* 
*  MODIFICATION HISTORY: 
* 
*/ 
 
 
/* 
* 
*  INCLUDE FILES 
* 
*/ 
 
#ifdef __VMS 
#include  <errno.h> 
#include  <stdio.h> 
#include  <socket.h> 
#include  <in.h> 
#include  <netdb.h>                /* Change hostent to comply with BSD 4.3. */ 
#include  <inet.h> 
#include  <ucx$inetdef.h>          /* INET symbol definitions. */ 
#else 
#include <errno.h> 
#include <sys/types.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h> 
#include <arpa/inet.h> 
#include <sys/uio.h> 
#endif 
 
 
/* 
* Functional Description 
* 
*        This example creates a socket of type SOCK_DGRAM (UDP), 
*        binds it, and sends a message to the given host and port number. 
*        Error messages are printed to the screen. 
* 
*        IPC calls used: 
*        bind 
*        close 
*        gethostbyname 
*        sendto        
*        shutdown 
*        socket        
* 
* Formal Parameters 
*        The client program expects two parameters: 
*        hostname ... name of remote host 
*        portnumber ... port where remote host(server) is listening 
* 
* 
* Routine Value 
* 
*        Status        
*/ 
 
 
/*--------------------------------------------------------------------*/ 
main(argc, argv) 
int        argc; 
char       **argv; 
{ 
 
        int     sock_1;                          /* Socket 1 descriptor.       */ 
        int     sendlen, tolen; 
static  char    sendbuf[] = "Hi there."; 
static struct   sockaddr_in sock2_name;          /* Address struct for socket2.*/ 
        int namelength; 
        struct  hostent hostentstruct;          /* Storage for hostent data.  */ 
        struct  hostent *hostentptr;            /* Pointer to hostent data.   */ 
        static  char hostname[256];             /* Name of local host.        */ 
        int        flag; 
        int        retval; 
 
 
        /* 
         * Check input parameters. 
         */ 
        if (argc != 3 ) 
                { 
                printf("Usage: client hostname portnumber.\n"); 
                exit(); 
                } 
 
 
        /* 
         * Open socket 1: AF_INET, SOCK_DGRAM. 
         */ 
        if ((sock_1 = socket (AF_INET, SOCK_DGRAM, 0)) == -1) 
                 { 
                perror( "socket"); 
                exit(); 
                } 
 
        
        /* 
         *Get pointer to network data structure for given host. 
         */ 
        if ((hostentptr = gethostbyname (argv[1])) == NULL) 
                { 
                perror( "gethostbyname"); 
                cleanup(sock_1); 
                } 
 
 
        /* 
         * Copy hostent data to safe storage. 
         */ 
        hostentstruct = *hostentptr; 
 
 
        /* 
         * Fill in the address structure for socket 2 (to receive message). 
         */ 
        sock2_name.sin_family = hostentstruct.h_addrtype; 
        sock2_name.sin_port = htons(atoi(argv[2])); 
        sock2_name.sin_addr = * ((struct in_addr *) hostentstruct.h_addr); 
 
 
        /* 
         * Initialize send block. 
         */ 
        sendlen = sizeof sendbuf; 
        tolen = sizeof sock2_name; 
        flag = 0;                /* flag may be MSG_OOB */ 
 
 
        /* 
         * Send message from socket 1 to socket 2. 
         */ 
        retval = sendto(sock_1, sendbuf, sendlen, flag, &sock2_name,tolen); 
        if (retval == -1) 
                { 
                perror ( "sendto"); 
                cleanup(sock_1); 
                } 
 
        /* 
         * Call cleanup to shut down and close socket. 
         */ 
        cleanup(sock_1); 
 
 } /* end main */ 
 
/*-----------------------------------------------------------*/ 
 
cleanup(socket) 
int        socket; 
        
{ 
        int        retval; 
 
        /* 
         * Shut down socket  completely. 
         */ 
        retval = shutdown(socket,2); 
        if (retval == -1) 
                perror ("shutdown"); 
 
 
        /* 
         * Close socket. 
         */ 
        retval = close (socket); 
        if (retval) 
                perror ("close"); 
 
        exit(); 
 
} /* end cleanup */

Previous Next Contents Index