Now works between SUNs and VAXen

[unix-history] / usr / src / libexec / talkd / talkd.c

#ifndef lint
static  char sccsid[] = "@(#)talkd.c    1.3 (Berkeley) %G%";
#endif

/*
* The top level of the daemon, the format is heavily borrowed
* from rwhod.c. Basically: find out who and where you are; 
* disconnect all descriptors and ttys, and then endless
* loop on waiting for and processing requests
*/
#include <stdio.h>
#include <errno.h>
#include <signal.h>

#include "ctl.h"

struct  sockaddr_in sin = { AF_INET };

CTL_MSG         request;
CTL_RESPONSE    response;

int     sockt;
int     debug = 0;
FILE    *debugout;
int     timeout();
long    lastmsgtime;

char    hostname[32];

#define TIMEOUT 30
#define MAXIDLE 120

main(argc, argv)
       int argc;
       char *argv[];
{
       struct sockaddr_in from;
       int fromlen, cc;
       
       if (debug)
               debugout = (FILE *)fopen ("/usr/tmp/talkd.msgs", "w");

       if (getuid()) {
               fprintf(stderr, "Talkd : not super user\n");
               exit(1);
       }
       gethostname(hostname, sizeof (hostname));
       (void) chdir("/dev");
       signal(SIGALRM, timeout);
       alarm(TIMEOUT);
       for (;;) {
               extern int errno;

               fromlen = sizeof(from);
               cc = recvfrom(0, (char *)&request, sizeof (request), 0,
                   &from, &fromlen);
               if (cc != sizeof(request)) {
                       if (cc < 0 && errno != EINTR)
                       perror("recvfrom");
                       continue;
               }
               lastmsgtime = time(0);
               swapmsg(&request);
               if (debug) print_request(&request, fp);
               process_request(&request, &response);
               /* can block here, is this what I want? */
               cc = sendto(sockt, (char *) &response,
                   sizeof (response), 0, &request.ctl_addr,
                   sizeof (request.ctl_addr));
               if (cc != sizeof(response))
                       perror("sendto");
       }
       if (debug) close (debugout);
}

timeout()
{

       if (time(0) - lastmsgtime >= MAXIDLE)
               exit(0);
       alarm(TIMEOUT);
}

#define swapshort(a) (((a << 8) | ((unsigned short) a >> 8)) & 0xffff)
#define swaplong(a) ((swapshort(a) << 16) | (swapshort(((unsigned)a >> 16))))

/*  
* heuristic to detect if need to swap bytes
*/

swapmsg(req)
       CTL_MSG *req;
{
       if (req->ctl_addr.sin_family == swapshort(AF_INET)) {
               req->id_num = swaplong(req->id_num);
               req->pid = swaplong(req->pid);
               req->addr.sin_family = swapshort(req->addr.sin_family);
               req->ctl_addr.sin_family =
                       swapshort(req->ctl_addr.sin_family);
       }
}