Amiga Developer CD 2.1/Amiga Developer CD v2.1.iso/Reference/DevCon/Milan_1991/Devcon91.2/Network/Socket/examples/server2.c

C/C++ Source or Header | 1992-09-01 | 6.8 KB | 274 lines

/*
**  server2.c
**
**  Written by Dale Larson, Software Engineer, Commodore-Amiga, Inc.
**  Copyright 1991, Commodore-Amiga, Inc.
**  Permission to use granted provided this notice remains intact.
**
**  This is a version of the ncopy server which processes multiple requests
**  simultaneously.  It spawns multiple processes to do so (it could also
**  use selectwait() to do [see server3.c]).  It is more complex than the
**  simple server, but not much, and it is nicer under frequent and/or heavy
**  use.  It also allows users to copy a file from one location on a remote
**  machine to another location on the same remote machine (i.e.
**  "ncopy sprite!ram:x sprite!work:y").  A system requester will not
**  pop up if the server recieves a request to read/write to/from a
**  non-existent device.
**
**  This server has no provision for exiting.
**
**  You should be familiar with the ncopy client (ncopy.c and transfer.c) and
**  the simple ncopy server (server1.c) before studying this server.
**
**  Thanks to Randell Jessup for his idea on how to easily arbitrate access
**  to the global Ns (which is used to pass info to child processes).
*/


#include "ncopy.h"

struct Library *SockBase;
#define MAXSOCKS 10

char vers[] = "\0$VER: server2 1.0 (25.02.91)";

void send_file(int s, BPTR file);
void get_file(int s, BPTR file);
void handle_request(void);
int  init(void);

/*  Not in SAS 5.10 or Manx 5.0d includes  */
struct Process *CreateNewProcTags( unsigned long tag1type, ... );

/*  global variable for New socket read by new processes:  */
int Ns = 0;


/*
**  main()
**
**  Call init() then wait to accept connections. Once a connection has been
**  accepted, start a new process to execute the handler function with the
**  socket which accept() connected to a remote machine.  Go back to accepting
**  connections.
*/
main(int argc, char **argv)
{
int s;             /*  socket to accept connections on  */
struct Process *pid;

    s = init();

    /*
    **  Accept connections from s and process them on ns.
    */
    while(1)
    {
        /*
        **  Make sure that there is not a child process which hasn't
        **  had a chance to copy its socket.  Ns must be initialized
        **  to zero before this while() and children must set Ns
        **  to zero when they have copied it.
        */
        if(Ns)
        {
            Delay(1);
            continue;
        }
        if( (Ns = accept(s,NULL,NULL)) >= 0 )
        {
        static char proc_name[20];

            sprintf(proc_name, "ncopy server #%2d", Ns);
            pid = CreateNewProcTags(NP_Entry, (LONG)handle_request,
                        NP_Name, (LONG)proc_name,
                        NP_WindowPtr, -1L,
                        TAG_DONE);
            if(!pid)
            {
                s_close(Ns);
                Ns = 0;
            }
        }
    }
}


/*
**  init()
**
**  Get a socket, bind a name to it, express a willingness to accept
**  connections to it (listen) and return the socket.  Exit on error.
*/
int init(void)
{
struct sockaddr_in sin;    /*  socket address (internet) to establish  */
int s,             /*  socket to accept connections on  */
    len = sizeof(sin);

    /*  Open Shared Socket library:
    */
        if(SockBase = OpenLibrary( "inet:libs/socket.library", 0L ))
        {
                setup_sockets( MAXSOCKS, &errno );
    }else
    {
        puts("Can't open socket.library.");
        exit(RETURN_ERROR);
    }

    /*
    **  Initialize a socket.
    */
    if( (s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket");
        exit(RETURN_ERROR);
    }

    /*
    **  Bind name to socket.
    **  Since we got sin off the stack, it could contain anything, and so
    **  we zero it before initializing it.
    */
    bzero(&sin, len);
    sin.sin_family = AF_INET;
    /*
    **  While prototyping a program, pick an unused port number above
    **  1024 like I did here.  For a real program, assign a name and a
    **  port number above 1024 and stick it in inet:db/servers on all
    **  machines which will use the application.  That way the user can
    **  reconfigure port numbers used by new applications if necessary.
    **  You can modify the server to get the port number from the
    **  database by using code like this (instead of "sin.sin_port=
    **  htons(6666)" below):
    **
    **  struct servent *servptr;
    **  char serv[] = "servicename";
    **
    **  if( (servptr = getservbyname(serv, "tcp")) == NULL)
    **  {
    **      printf("Unknown service %s.  Check inet:db/services.\n",serv);
    **    return RETURN_ERROR;
    **  }
    **  sin.sin_port = servptr->s_port;
    */
    sin.sin_port = htons(6666);
    sin.sin_addr.s_addr = INADDR_ANY;
    if(bind(s, (struct sockaddr *)&sin, len) < 0)
    {
        perror("bind");
        exit(RETURN_ERROR);
    }

    /*
    **  Put socket into "listen" state (ready to accept connections).
    */
    listen(s,5);
    return s;
}


/*
**  handle_request()
**
**  Handles a request to send or receive a file on a given socket.
**  Handling a request consists of the following:
**      1)  receive the mode (send or receive -- MODE_OLDFILE or MODE_NEWFILE)
**    2)  receive the filename
**    3)  attempt to open the file
**    4)  return "\0" for succesful open,
**        specially formated informative error message otherwise
**    5)  call function to send or receive the file
**    6)  closes the file we opened and the socket we were passed
*/
void handle_request(void)
{
int s;        /*  socket passed by parent  */
char buffer[LENGTH];
int mode;    /*  AmigaDOS file open mode (MODE_OLDFILE or MODE_NEWFILE)  */
BPTR file;    /*  BCPL pointer to an AmigaDOS file handle  */

    geta4();


        s = Ns;
    Ns = 0;  /*  So that parent may feel free to use it again  */


    /*  Get the mode.
    **  Don't worry about making sure that we got what we wanted because we
    **  can't really screw anything up and we can't send an error message
    **  if our communcications are error-prone.
    */
    recv(s, (char *)&mode, sizeof(int), 0);

    /*  Get the filename which we'll read or write (depending on mode).
    **  (Assume that we get only null-terminated strings.)
    */
    recv(s, buffer, LENGTH, 0);

    /*
    **  Attempt to open file.
    */
    if( !(file = Open(buffer, mode)) )
    {
    int len;

        len = strlen(buffer);
        strncat(buffer, "': ", LENGTH-4);  /*  4 not 3 'cause of nul  */
        Fault(IoErr(), NULL, buffer+len+3, LENGTH-len-4);
        send(s, buffer, strlen(buffer)+1, 0);
        s_close(s);
        return;
    }

    /*
    **  Indicate succesful opening of file.
    */
    send(s, "\0", 1, 0);

    /*
    **  Send or recieve the file.
    */
    if(mode == MODE_OLDFILE)
        send_file(s, file);
    else
        get_file(s, file);

    Close(file);
    s_close(s);
}


void send_file(int s, BPTR file)
{
char    buffer[LENGTH];
long    actualLength;

    do
    {
        actualLength = Read(file, (void *)buffer, LENGTH);
            if(actualLength < 0)
            return;  /*  Error, but we have no way to report it.  */
        if(send(s, buffer, actualLength, 0) < 0)
            return;  /*  Error, but we have no way to report it.  */
    }while(actualLength);
}


void get_file(int s, BPTR file)
{
char    buffer[LENGTH];
int     n;

    do
    {
        n = recv(s, buffer, LENGTH, 0);
        if(n < 0)
            return;  /*  Error, but we have no way to report it.  */
        if(Write(file, (void *)buffer, n) < 0)
            return;  /*  Error, but we have no way to report it.  */
    }while(n);
}