v04i036: ringback getty for sharing a phone line
Jon Zeeff
zeeff at b-tech.UUCP
Fri Aug 26 04:19:00 AEST 1988
Posting-number: Volume 4, Issue 36
Submitted-by: "Jon Zeeff" <zeeff at b-tech.UUCP>
Archive-name: ringback
[People, *please* "shar" your submissions!!!!!
Apologies for the delay; "jetroff" was clogging the pipes. It will probably
start going out on September 6. ++bsa]
#! /bin/sh
echo x - ringback.c
sed 's/^X//' << \EOF > ringback.c
X/*
X
XRingback.c V1.3
X
XThis program implements a ring-back system that allows a phone line
Xthat is normally used as a voice line and a dial-out data line to be
Xused as a limited dial-in data and voice line. It does not interfere
Xwith the use of the line for an answering machine.
X
XIt solves a problem for my situation:
X
X1) I am normally in my office. The phone line is used for dial-out via
Xmodem and dial-in/dial-out voice traffic.
X
X2) I sometimes travel, at which time I connect an answering machine to
Xthe line.
X
X3) I'd like to be able to call in to my system via modem when I am
Xtravelling, without interfering with others use of my answering
Xmachine.
X
X4) I don't want to pay for another phone line.
X
XThis program functions by watching a tty port for an incoming call on
Xa smart modem. Forty seconds after an incoming call, it will spawn a
Xgetty on the line. If no one calls and logs in, the getty will be
Xkilled by an uncaught alarm and the line will be set back to a no
Xanswer state.
X
XThis implements a ringback dialin system. Just call, wait a minute,
Xand call again.
X
XIf the program notices that a user (uucp or kermit) is using the line
Xfor an outgoing call, it will back off until that call is completed.
X(Note: the first modem response char will be eaten. Uucp dialing scripts
Xshould be set up to tolerate this.)
X
XWritten for Sys V.3 and HDB uucp (but easily modified for others)
X
XTwo arguments must be present - tty and type
X
XSample lines from /etc/inittab:
X rb:1234:respawn:/etc/ringback tty1 1200
X
XMake sure that you trust the people who are allowed to login on this
Xline. It is possible for them to dial-out on the line.
X
XTo install:
X
X1) Edit TTYID and TTYGID and UUGETTY.
X2) Compile and install as /etc/ringback
X3) Create an initab line like the above one.
X
X - Jon Zeeff (umix!b-tech!zeeff)
X
XThis program is in the public domain.
X
X*/
X
X#include <stdio.h>
X#include <sys/types.h>
X#include <sys/stat.h>
X#include <signal.h>
X#include <fcntl.h>
X#include <termio.h>
X
Xchar *strcpy();
Xchar *strcat();
Xunsigned sleep();
Xunsigned alarm();
Xvoid exit();
X
X/* the id and gid for normal ownership of tty lines (usually uucp) */
X
X#define TTYID 5 /* uucp */
X#define TTYGID 11 /* staff */
X
X/* if you have a getty/tty/modem combination that doesn't get in a babbling
X getty loop, then there is no need to define this. If you do, make sure
X that /etc/uugetty exists.
X*/
X#define UUGETTY /* #define UUGETTY */
X
Xmain(argc,argv)
Xint argc;
Xchar **argv;
X{
X
Xchar c;
XFILE *tty0,*tty1,*tty2;
X#ifdef DEBUG
XFILE *console;
X#endif
XFILE *tty;
XFILE *lock;
Xstruct termio ttymodes;
Xstruct stat buf;
Xchar tty_lock[100];
Xchar tty_name[100];
Xint i;
X
X/* name and location of tty locks - change this as needed */
X
Xstrcpy(tty_lock,"/usr/spool/locks/LCK..");
Xstrcat(tty_lock,argv[1]);
X
Xstrcpy(tty_name,"/dev/");
Xstrcat(tty_name,argv[1]);
X
Xif (argc != 3) exit(2);
X
Xunlink(tty_lock);
Xumask(022);
X
Xsignal(SIGHUP,SIG_IGN);
Xsignal(SIGINT,SIG_IGN);
Xsignal(SIGQUIT,SIG_IGN);
Xsignal(SIGTERM,SIG_IGN);
X
Xfor (;;) {
X
X /* Set the line permissions, owner, and group for dial-out use */
X
X chown(tty_name,TTYID,TTYGID);
X chmod(tty_name,0660);
X
X /* Open line - getty will close the first 3, so make sure we are #4 */
X /* so that the modem doesn't get reset on dtr drop and our autoanswer */
X /* setting don't get undone. */
X
X tty0 = fopen(tty_name,"r+");
X tty1 = fopen(tty_name,"r+");
X tty2 = fopen(tty_name,"r+");
X tty = fopen(tty_name,"r+");
X
X fclose(tty0); fclose(tty1); fclose(tty2);
X
X#ifdef DEBUG
Xconsole = fopen("/dev/console","w");
Xfprintf(console,"check 1\n"); fflush(console);
X#endif
X
X ttymodes.c_iflag = 0;
X ttymodes.c_oflag = NL1 | CR3;
X ttymodes.c_cflag = 0;
X ttymodes.c_lflag = 0;
X ttymodes.c_line = 0;
X for (i = 0; i < NCC; ++i) ttymodes.c_cc[i] = 0;
X ttymodes.c_cc[VMIN] = 1; /* min number of characters */
X ttymodes.c_cc[VTIME] = 0; /* no max time before return */
X ioctl(fileno(tty),TCSETA,&ttymodes); /* hang up the line */
X sleep(1);
X ttymodes.c_cflag = B1200 | CS8 | CREAD | HUPCL;
X ioctl(fileno(tty),TCSETA,&ttymodes);
X sleep(1);
X#ifdef DEBUG
Xfprintf(console,"check 1.3\n"); fflush(console);
X#endif
X
X /* setup the modem */
X
X fputs("AT\r",tty); fflush(tty); sleep(1);
X fputs("ATZ\r",tty); fflush(tty); sleep(2);
X fputs("ATS0=0\r",tty); fflush(tty); sleep(1); /* Don't answer phone */
X fputs("ATE0\r",tty); fflush(tty); sleep(1);
X fputs("ATV0\r",tty); fflush(tty); sleep(1);
X fputs("ATQ0\r",tty); fflush(tty); sleep(1);
X
X#ifdef DEBUG
Xfprintf(console,"check 2\n"); fflush(console);
X#endif
X fcntl(fileno(tty),F_SETFL,O_NDELAY); /* Set to nonblocking reads */
X while (read(fileno(tty),&c,(unsigned)1) == 1); /* Flush input */
X fcntl(fileno(tty),F_SETFL,O_RDWR); /* Set to blocking reads */
X
X /* Wait for incoming call ('2') or other usage (uucp or user) */
X
X /* Get char from tty port */
X
X while (read(fileno(tty),&c,(unsigned)1) != 1);
X
X /*
X If we receive a '2' and no lock file is present, we can be sure
X that it is not someone calling out.
X */
X
X#ifdef DEBUG
Xfprintf(console,"check 2.5 %d\n",c); fflush(console);
X#endif
X
X if ((c&0x7f) == '2' && stat(tty_lock,&buf) == -1) {
X
X /* create a hdb style lock file */
X
X lock = fopen(tty_lock,"w");
X if (lock) {
X fprintf(lock,"%10.10d\n",(int)getpid());
X fclose(lock);
X }
X
X /* wait for this call to end */
X
X sleep(32); /* should be long enough for answering machine
X to answer if they let it ring. */
X
X /* Setup modem for incoming call */
X
X fputs("AT\r",tty);fflush(tty);sleep(1);
X fputs("ATZ\r",tty);fflush(tty);sleep(1);
X fputs("ATQ1\r",tty);fflush(tty);sleep(1);
X fputs("ATS0=1\r",tty);fflush(tty);sleep(5);
X
X#ifdef DEBUG
Xfprintf(console,"check 4\n"); fflush(console);
X#endif
X
X /* set things up so the getty will live a short life */
X
X alarm(120);
X
X#ifndef UUGETTY
X execl("/etc/getty","getty","-t","90","-h",
X argv[1],argv[2],(char *)0);
X#else
X unlink(tty_lock);
X execl("/etc/uugetty","uugetty","-r","-h","-t","90",
X argv[1],argv[2],(char *)0);
X#endif
X
X#ifdef DEBUG
Xfprintf(console,"check 5\n"); fflush(console);
X#endif
X } else { /* Must be someone using line */
X
X fclose(tty); /* Release line */
X
X /* Loop until lock file goes away (uucp or user done) */
X
X do {
X while (stat(tty_lock,&buf) == 0) sleep(40);
X sleep(40);
X } while (stat(tty_lock,&buf) == 0);
X
X } /* end_if */
X
X } /* next */
X
X}
EOF
exit 0
--
Jon Zeeff Branch Technology,
uunet!umix!b-tech!zeeff zeeff%b-tech.uucp at umix.cc.umich.edu
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