IABSD.fr/src/libexec/comsat/comsat.c

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• Author : guenther
  Date : 2023-03-08 04:43:04
  Hash : 5b133f3f
  Message : Delete obsolete /* ARGSUSED */ lint comments. ok miod@ millert@

• libexec/comsat/comsat.c

• /*	$OpenBSD: comsat.c,v 1.51 2023/03/08 04:43:05 guenther Exp $	*/
  
  /*
   * Copyright (c) 1980, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/limits.h>
  #include <sys/socket.h>
  #include <sys/stat.h>
  #include <sys/wait.h>
  
  #include <netinet/in.h>
  
  #include <ctype.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <netdb.h>
  #include <limits.h>
  #include <paths.h>
  #include <pwd.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <syslog.h>
  #include <termios.h>
  #include <unistd.h>
  #include <utmp.h>
  #include <vis.h>
  #include <err.h>
  
  int	debug = 0;
  #define	dsyslog	if (debug) syslog
  
  #define MAXIDLE	120
  
  char	hostname[HOST_NAME_MAX+1];
  struct	utmp *utmp = NULL;
  time_t	lastmsgtime;
  int	nutmp, uf;
  
  void jkfprintf(FILE *, char[], off_t);
  void mailfor(char *);
  void notify(struct utmp *, off_t);
  void readutmp(int);
  void doreadutmp(void);
  void reapchildren(int);
  
  volatile sig_atomic_t wantreadutmp;
  
  int
  main(int argc, char *argv[])
  {
  	struct sockaddr_storage from;
  	struct sigaction sa;
  	ssize_t cc;
  	socklen_t fromlen;
  	char msgbuf[100];
  	sigset_t sigset;
  
  	/* verify proper invocation */
  	fromlen = sizeof(from);
  	if (getsockname(0, (struct sockaddr *)&from, &fromlen) == -1) {
  		(void)fprintf(stderr,
  		    "comsat: getsockname: %s.\n", strerror(errno));
  		exit(1);
  	}
  
  	if (unveil(_PATH_MAILDIR, "r") == -1)
  		err(1, "unveil %s", _PATH_MAILDIR);
  	if (unveil(_PATH_UTMP, "r") == -1)
  		err(1, "unveil %s", _PATH_UTMP);
  	if (unveil("/tmp", "w") == -1)
  		err(1, "unveil /tmp");
  	if (unveil(_PATH_DEV, "rw") == -1)
  		err(1, "unveil %s", _PATH_DEV);
  	if (pledge("stdio rpath wpath proc tty", NULL) == -1)
  		err(1, "pledge");
  
  	openlog("comsat", LOG_PID, LOG_DAEMON);
  	if (chdir(_PATH_MAILDIR)) {
  		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
  		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
  		exit(1);
  	}
  	if ((uf = open(_PATH_UTMP, O_RDONLY)) == -1) {
  		syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP);
  		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
  		exit(1);
  	}
  	(void)time(&lastmsgtime);
  	(void)gethostname(hostname, sizeof(hostname));
  	doreadutmp();
  
  	(void)signal(SIGTTOU, SIG_IGN);
  
  	bzero(&sa, sizeof sa);
  	sigemptyset(&sa.sa_mask);
  	sa.sa_handler = readutmp;
  	sa.sa_flags = 0;			/* no SA_RESTART */
  	(void)sigaction(SIGALRM, &sa, NULL);
  
  	sa.sa_handler = reapchildren;
  	sa.sa_flags = SA_RESTART;
  	(void)sigaction(SIGCHLD, &sa, NULL);
  
  	for (;;) {
  		if (wantreadutmp) {
  			wantreadutmp = 0;
  			doreadutmp();
  		}
  
  		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
  		if (cc <= 0) {
  			if (errno != EINTR)
  				sleep(1);
  			continue;
  		}
  		if (!nutmp)		/* no one has logged in yet */
  			continue;
  		sigemptyset(&sigset);
  		sigaddset(&sigset, SIGALRM);
  		sigprocmask(SIG_SETMASK, &sigset, NULL);
  		msgbuf[cc] = '\0';
  		(void)time(&lastmsgtime);
  		mailfor(msgbuf);
  		sigemptyset(&sigset);
  		sigprocmask(SIG_SETMASK, &sigset, NULL);
  	}
  }
  
  void
  reapchildren(int signo)
  {
  	int save_errno = errno;
  
  	while (wait3(NULL, WNOHANG, NULL) > 0)
  		;
  	errno = save_errno;
  }
  
  void
  readutmp(int signo)
  {
  	wantreadutmp = 1;
  }
  
  void
  doreadutmp(void)
  {
  	static u_int utmpsize;		/* last malloced size for utmp */
  	static time_t utmpmtime;	/* last modification time for utmp */
  	struct stat statbf;
  	int n;
  
  	if (time(NULL) - lastmsgtime >= MAXIDLE)
  		exit(0);
  	(void)fstat(uf, &statbf);
  	if (statbf.st_mtime > utmpmtime) {
  		utmpmtime = statbf.st_mtime;
  		/* avoid int overflow */
  		if (statbf.st_size > INT_MAX - 10 * sizeof(struct utmp)) {
  			syslog(LOG_ALERT, "utmp file excessively large");
  			exit(1);
  		}
  		if (statbf.st_size > utmpsize) {
  			u_int nutmpsize = statbf.st_size + 10 *
  			    sizeof(struct utmp);
  			struct utmp *u;
  
  			if ((u = recallocarray(utmp, utmpsize,
  			    nutmpsize, 1)) == NULL) {
  				free(utmp);
  				syslog(LOG_ERR, "%s", strerror(errno));
  				exit(1);
  			}
  			utmp = u;
  			utmpsize = nutmpsize;
  		}
  		n = pread(uf, utmp, statbf.st_size, 0);
  		if (n == -1)
  			n = 0;
  		nutmp = n / sizeof(struct utmp);
  		dsyslog(LOG_DEBUG, "read %d utmp entries", nutmp);
  	}
  	(void)alarm(15);
  }
  
  void
  mailfor(char *name)
  {
  	struct utmp *utp = &utmp[nutmp];
  	char utname[UT_NAMESIZE+1];
  	const char *errstr;
  	char *cp;
  	off_t offset;
  
  	dsyslog(LOG_DEBUG, "mail for '%s'", name);
  	if (!(cp = strchr(name, '@')))
  		return;
  	*cp++ = '\0';
  	cp[strcspn(cp, " \t\n")] = '\0';
  	offset = strtonum(cp, 0, LLONG_MAX, &errstr);
  	if (errstr) {
  		syslog(LOG_ERR, "'%s' is %s", cp + 1, errstr);
  		return;
  	}
  	while (--utp >= utmp) {
  		memcpy(utname, utp->ut_name, UT_NAMESIZE);
  		utname[UT_NAMESIZE] = '\0';
  		dsyslog(LOG_DEBUG, "check %s against %s", name, utname);
  		if (!strncmp(utname, name, UT_NAMESIZE))
  			notify(utp, offset);
  	}
  }
  
  static char *cr;
  
  void
  notify(struct utmp *utp, off_t offset)
  {
  	int fd;
  	FILE *tp;
  	struct stat stb;
  	struct termios ttybuf;
  	char tty[PATH_MAX], name[UT_NAMESIZE + 1];
  
  	(void)snprintf(tty, sizeof(tty), "%s%.*s",
  	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
  	if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) {
  		/* A slash is an attempt to break security... */
  		syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty);
  		return;
  	}
  	if (stat(tty, &stb) || !(stb.st_mode & S_IEXEC)) {
  		dsyslog(LOG_DEBUG, "%.*s: wrong mode on %s",
  		    (int)sizeof(utp->ut_name), utp->ut_name, tty);
  		return;
  	}
  	dsyslog(LOG_DEBUG, "notify %.*s on %s", (int)sizeof(utp->ut_name),
  	    utp->ut_name, tty);
  	if (fork())
  		return;
  	(void)signal(SIGALRM, SIG_DFL);
  	(void)alarm(30);
  	fd = open(tty, O_WRONLY);
  	if (fd == -1 || (tp = fdopen(fd, "w")) == NULL) {
  		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
  		_exit(1);
  	}
  	(void)tcgetattr(fileno(tp), &ttybuf);
  	cr = (ttybuf.c_oflag & ONLCR) && (ttybuf.c_oflag & OPOST) ?
  	    "\n" : "\n\r";
  	memcpy(name, utp->ut_name, UT_NAMESIZE);
  	name[UT_NAMESIZE] = '\0';
  	(void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived:%s----%s",
  	    cr, name, (int)sizeof(hostname), hostname, cr, cr);
  	jkfprintf(tp, name, offset);
  	(void)fclose(tp);
  	_exit(0);
  }
  
  void
  jkfprintf(FILE *tp, char name[], off_t offset)
  {
  	char *cp, ch;
  	char visout[5], *s2;
  	FILE *fi;
  	int linecnt, charcnt, inheader;
  	char line[BUFSIZ];
  
  	if ((fi = fopen(name, "r")) == NULL)
  		return;
  
  	(void)fseeko(fi, offset, SEEK_SET);
  	/*
  	 * Print the first 7 lines or 560 characters of the new mail
  	 * (whichever comes first).  Skip header crap other than
  	 * From, Subject, To, and Date.
  	 */
  	linecnt = 7;
  	charcnt = 560;
  	inheader = 1;
  	while (fgets(line, sizeof(line), fi) != NULL) {
  		if (inheader) {
  			if (line[0] == '\n') {
  				inheader = 0;
  				continue;
  			}
  			if (line[0] == ' ' || line[0] == '\t' ||
  			    (strncmp(line, "From:", 5) &&
  			    strncmp(line, "Subject:", 8)))
  				continue;
  		}
  		if (linecnt <= 0 || charcnt <= 0) {
  			(void)fprintf(tp, "...more...%s", cr);
  			(void)fclose(fi);
  			return;
  		}
  		/* strip weird stuff so can't trojan horse stupid terminals */
  		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
  			ch = toascii(ch);
  			vis(visout, ch, VIS_SAFE|VIS_NOSLASH, cp[1]);
  			for (s2 = visout; *s2; s2++)
  				(void)fputc(*s2, tp);
  		}
  		(void)fputs(cr, tp);
  		--linecnt;
  	}
  	(void)fprintf(tp, "----%s\n", cr);
  	(void)fclose(fi);
  }