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https://github.com/sheumann/hush.git
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197 lines
4.8 KiB
C
197 lines
4.8 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* bare bones 'talk to modem' program - similar to 'cu -l $device'
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* inspired by mgetty's microcom
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*
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* Copyright (C) 2007 by Vladimir Dronnikov <dronnikov@gmail.ru>
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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/* All known arches use small ints for signals */
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static volatile smallint signalled;
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static void signal_handler(int signo)
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{
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signalled = signo;
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}
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// set canonical tty mode
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static void xget1(int fd, struct termios *t, struct termios *oldt)
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{
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tcgetattr(fd, oldt);
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*t = *oldt;
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cfmakeraw(t);
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// t->c_lflag &= ~(ISIG|ICANON|ECHO|IEXTEN);
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// t->c_iflag &= ~(BRKINT|IXON|ICRNL);
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// t->c_oflag &= ~(ONLCR);
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// t->c_cc[VMIN] = 1;
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// t->c_cc[VTIME] = 0;
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}
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static int xset1(int fd, struct termios *tio, const char *device)
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{
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int ret = tcsetattr(fd, TCSANOW, tio);
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if (ret) {
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bb_perror_msg("can't tcsetattr for %s", device);
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}
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return ret;
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}
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int microcom_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int microcom_main(int argc, char **argv)
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{
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struct pollfd pfd[2];
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int nfd;
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int sfd;
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/* #define sfd (pfd[0].fd) - gcc 4.2.1 is still not smart enough */
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char *device_lock_file;
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const char *opt_s = "9600";
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speed_t speed;
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const char *opt_t = "100"; // 0.1 sec timeout
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unsigned timeout;
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struct termios tio0, tiosfd, tio;
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bool istty;
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// fetch options
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opt_complementary = "-1"; /* at least one arg should be there */
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getopt32(argv, "s:t:", &opt_s, &opt_t);
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argc -= optind;
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argv += optind;
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// check sanity
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speed = xatou(opt_s);
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timeout = xatou(opt_t);
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device_lock_file = (char *)bb_basename(argv[0]);
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// try to create lock file in /var/lock
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device_lock_file = xasprintf("/var/lock/LCK..%s", device_lock_file);
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sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
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if (sfd < 0) {
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if (errno == EEXIST)
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bb_perror_msg_and_die("can't lock device");
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// We don't abort on other errors: /var/lock can be
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// non-writable or non-existent
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if (ENABLE_FEATURE_CLEAN_UP)
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free(device_lock_file);
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device_lock_file = NULL;
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} else {
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// %4d to make mgetty happy. It treats 4-bytes lock files as binary,
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// not text, PID. Making 5+ char file. Brrr...
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char *s = xasprintf("%4d\n", getpid());
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write(sfd, s, strlen(s));
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if (ENABLE_FEATURE_CLEAN_UP)
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free(s);
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close(sfd);
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}
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// setup signals
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sig_catch(SIGHUP, signal_handler);
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sig_catch(SIGINT, signal_handler);
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sig_catch(SIGTERM, signal_handler);
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sig_catch(SIGPIPE, signal_handler);
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// error exit code if we fail to open the device
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signalled = 1;
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// open device
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sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK);
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if (sfd < 0)
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goto unlock_and_exit;
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fcntl(sfd, F_SETFL, O_RDWR | O_NOCTTY);
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/* put stdin to "raw mode" (if stdin is a TTY),
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handle one character at a time */
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istty = isatty(STDIN_FILENO);
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if (istty) {
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xget1(STDIN_FILENO, &tio, &tio0);
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if (xset1(STDIN_FILENO, &tio, "stdin"))
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goto close_unlock_and_exit;
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// tcflush(STDIN_FILENO, TCIFLUSH);
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timeout = -1; // tty input? -> set infinite timeout for poll()
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}
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// same thing for modem
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xget1(sfd, &tio, &tiosfd);
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// order device to hang up at exit
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tio.c_cflag |= (CREAD|HUPCL);
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// set device speed
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cfsetspeed(&tio, tty_value_to_baud(speed));
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if (xset1(sfd, &tio, argv[0]))
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goto restore0_close_unlock_and_exit;
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// main loop: check with poll(), then read/write bytes across
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pfd[0].fd = sfd;
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pfd[0].events = POLLIN;
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pfd[1].fd = STDIN_FILENO;
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pfd[1].events = POLLIN;
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// TODO: on piped input should we treat NL as CRNL?!
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signalled = 0;
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// initially we have to poll() both stdin and device
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nfd = 2;
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while (!signalled && nfd && safe_poll(pfd, nfd, timeout) > 0) {
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int i;
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for (i = 0; i < nfd; ++i) {
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if (pfd[i].revents & (POLLIN | POLLHUP)) {
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// int fd;
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char c;
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// read a byte
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if (safe_read(pfd[i].fd, &c, 1) < 1) {
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// this can occur at the end of piped input
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// from now we only poll() for device
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nfd--;
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continue;
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}
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// fd = STDOUT_FILENO;
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// stdin requires additional processing
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// (TODO: must be controlled by command line switch)
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if (i) {
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// ^@ sends Break
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if (0 == c) {
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tcsendbreak(sfd, 0);
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continue;
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}
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// ^X exits
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if (24 == c)
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goto done;
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// fd = sfd;
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}
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// write the byte
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write(i ? sfd : STDOUT_FILENO, &c, 1);
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// write(fd, &c, 1);
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// give device a chance to get data
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// wait 0.01 msec
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// (TODO: seems to be arbitrary to me)
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if (i)
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usleep(10);
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}
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}
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}
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done:
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tcsetattr(sfd, TCSANOW, &tiosfd);
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restore0_close_unlock_and_exit:
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if (istty) {
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// tcflush(STDIN_FILENO, TCIFLUSH);
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tcsetattr(STDIN_FILENO, TCSANOW, &tio0);
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}
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close_unlock_and_exit:
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if (ENABLE_FEATURE_CLEAN_UP)
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close(sfd);
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unlock_and_exit:
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// delete lock file
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if (device_lock_file) {
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unlink(device_lock_file);
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if (ENABLE_FEATURE_CLEAN_UP)
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free(device_lock_file);
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}
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return signalled;
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}
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