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发信人: ayanami (Kanzaki Hitomi), 信区: Unix
标  题: Re: how to post  messages on remote machine?
发信站: BBS 水木清华站 (Wed Nov 26 08:04:01 1997)

【在 zalex (Easy) 的大作中提到: 】
∶ Hi:
∶    In my course I need to write a program to talk.It's much like the talk
∶ in UNIX.The first problem is:How can I notify the people on a remote machine?
∶ Tell him someone wants to talk to him and please run 'xxxtalk'?
∶    The second problem is : I plan to hack xemacs to do it. Will this be too
∶ hard?
∶     Thanks.
here are some source code. Hope it will help.
#ifndef lint
static char sccsid[] = "@(#)invite.c    8.1 (Berkeley) 6/6/93";
#endif /* not lint */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <signal.h>
#include <netinet/in.h>
#include <protocols/talkd.h>
#include <errno.h>
#include <setjmp.h>
#include "talk_ctl.h"
#include "talk.h"

/*
* There wasn't an invitation waiting, so send a request containing
* our sockt address to the remote talk daemon so it can invite
* him
*/

/*
* The msg.id's for the invitations
* on the local and remote machines.
* These are used to delete the
* invitations.
*/
int     local_id, remote_id;
jmp_buf invitebuf;

void
invite_remote()
{
        int nfd, read_mask, template, new_sockt;
        struct itimerval itimer;
        CTL_RESPONSE response;

        itimer.it_value.tv_sec = RING_WAIT;
        itimer.it_value.tv_usec = 0;
        itimer.it_interval = itimer.it_value;
        if (listen(sockt, 5) != 0)
                p_error("Error on attempt to listen for caller");
#ifdef MSG_EOR
        /* copy new style sockaddr to old, swap family (short in old) */
        msg.addr = *(struct osockaddr *)&my_addr;  /* XXX new to old  style*/
        msg.addr.sa_family = htons(my_addr.sin_family);
#else
        msg.addr = *(struct sockaddr *)&my_addr;
#endif
        msg.id_num = htonl(-1);         /* an impossible id_num */
        invitation_waiting = 1;
        announce_invite();
        /*
         * Shut off the automatic messages for a while,
         * so we can use the interupt timer to resend the invitation
         */
        end_msgs();
        setitimer(ITIMER_REAL, &itimer, (struct itimerval *)0);
        message("Waiting for your party to respond");
        signal(SIGALRM, re_invite);
        (void) setjmp(invitebuf);
        while ((new_sockt = accept(sockt, 0, 0)) < 0) {
                if (errno == EINTR)
                        continue;
                p_error("Unable to connect with your party");
        }
        close(sockt);
        sockt = new_sockt;

        /*
         * Have the daemons delete the invitations now that we
         * have connected.
         */
        current_state = "Waiting for your party to respond";
        start_msgs();

        msg.id_num = htonl(local_id);
        ctl_transact(my_machine_addr, msg, DELETE, &response);
        msg.id_num = htonl(remote_id);
        ctl_transact(his_machine_addr, msg, DELETE, &response);
        invitation_waiting = 0;
}

/*
* Routine called on interupt to re-invite the callee
*/
/* ARGSUSED */
void
re_invite(signo)
        int signo;
{

        message("Ringing your party again");
        waddch(my_win.x_win, '\n');
        if (current_line < my_win.x_nlines - 1)
                current_line++;
        /* force a re-announce */
        msg.id_num = htonl(remote_id + 1);
        announce_invite();
        longjmp(invitebuf, 1);
}

static  char *answers[] = {
        "answer #0",                                    /* SUCCESS */
        "Your party is not logged on",                  /* NOT_HERE */
        "Target machine is too confused to talk to us", /* FAILED */
        "Target machine does not recognize us",         /* MACHINE_UNKNOWN */
        "Your party is refusing messages",              /* PERMISSION_REFUSED */
        "Target machine can not handle remote talk",    /* UNKNOWN_REQUEST */
        "Target machine indicates protocol mismatch",   /* BADVERSION */
        "Target machine indicates protocol botch (addr)",/* BADADDR */
        "Target machine indicates protocol botch (ctl_addr)",/* BADCTLADDR */
};
#define NANSWERS        (sizeof (answers) / sizeof (answers[0]))

/*
* Transmit the invitation and process the response
*/
void
announce_invite()
{
        CTL_RESPONSE response;

        current_state = "Trying to connect to your party's talk daemon";
        ctl_transact(his_machine_addr, msg, ANNOUNCE, &response);
        remote_id = response.id_num;
        if (response.answer != SUCCESS) {
                if (response.answer < NANSWERS)
                        message(answers[response.answer]);
                quit();
        }
        /* leave the actual invitation on my talk daemon */
        ctl_transact(my_machine_addr, msg, LEAVE_INVITE, &response);
        local_id = response.id_num;
}

/*
* Tell the daemon to remove your invitation
*/
void
send_delete()
{

        msg.type = DELETE;
        /*
         * This is just a extra clean up, so just send it
         * and don't wait for an answer
         */
        msg.id_num = htonl(remote_id);
        daemon_addr.sin_addr = his_machine_addr;
        if (sendto(ctl_sockt, &msg, sizeof (msg), 0,
            (struct sockaddr *)&daemon_addr,
            sizeof (daemon_addr)) != sizeof(msg))
                perror("send_delete (remote)");
        msg.id_num = htonl(local_id);
        daemon_addr.sin_addr = my_machine_addr;
        if (sendto(ctl_sockt, &msg, sizeof (msg), 0,
            (struct sockaddr *)&daemon_addr,
            sizeof (daemon_addr)) != sizeof (msg))
                perror("send_delete (local)");

}

--
Kanzaki Hitomi <---> Van Fanel     Tenku no Escaflowne
Ayanami Rei    <---> Ikari Shinji  Shin seiki Evangelion
Tamahome       <---> Miaka         Fushigi Yuugi
dream lovers.... Fansubber wanna-be

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