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/* $OpenBSD: comsat.c,v 1.48 2017/04/03 17:23:39 tedu Exp $ */ |
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/* |
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* Copyright (c) 1980, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <sys/limits.h> |
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#include <sys/socket.h> |
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#include <sys/stat.h> |
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#include <sys/wait.h> |
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#include <netinet/in.h> |
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#include <ctype.h> |
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#include <errno.h> |
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#include <fcntl.h> |
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#include <netdb.h> |
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#include <limits.h> |
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#include <paths.h> |
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#include <pwd.h> |
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#include <signal.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <syslog.h> |
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#include <termios.h> |
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#include <unistd.h> |
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#include <utmp.h> |
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#include <vis.h> |
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#include <err.h> |
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int debug = 0; |
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#define dsyslog if (debug) syslog |
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#define MAXIDLE 120 |
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char hostname[HOST_NAME_MAX+1]; |
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struct utmp *utmp = NULL; |
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time_t lastmsgtime; |
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int nutmp, uf; |
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void jkfprintf(FILE *, char[], off_t); |
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void mailfor(char *); |
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void notify(struct utmp *, off_t); |
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void readutmp(int); |
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void doreadutmp(void); |
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void reapchildren(int); |
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volatile sig_atomic_t wantreadutmp; |
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int |
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main(int argc, char *argv[]) |
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{ |
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struct sockaddr_storage from; |
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struct sigaction sa; |
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ssize_t cc; |
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socklen_t fromlen; |
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char msgbuf[100]; |
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sigset_t sigset; |
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/* verify proper invocation */ |
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fromlen = sizeof(from); |
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if (getsockname(0, (struct sockaddr *)&from, &fromlen) == -1) { |
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(void)fprintf(stderr, |
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"comsat: getsockname: %s.\n", strerror(errno)); |
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exit(1); |
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} |
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if (pledge("stdio rpath wpath proc tty flock cpath", NULL) == -1) |
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err(1, "pledge"); |
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openlog("comsat", LOG_PID, LOG_DAEMON); |
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if (chdir(_PATH_MAILDIR)) { |
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syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR); |
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(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0); |
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exit(1); |
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} |
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if ((uf = open(_PATH_UTMP, O_RDONLY)) == -1) { |
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syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP); |
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(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0); |
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exit(1); |
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} |
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(void)time(&lastmsgtime); |
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(void)gethostname(hostname, sizeof(hostname)); |
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doreadutmp(); |
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(void)signal(SIGTTOU, SIG_IGN); |
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bzero(&sa, sizeof sa); |
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sigemptyset(&sa.sa_mask); |
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sa.sa_handler = readutmp; |
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sa.sa_flags = 0; /* no SA_RESTART */ |
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(void)sigaction(SIGALRM, &sa, NULL); |
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sa.sa_handler = reapchildren; |
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sa.sa_flags = SA_RESTART; |
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(void)sigaction(SIGCHLD, &sa, NULL); |
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for (;;) { |
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if (wantreadutmp) { |
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wantreadutmp = 0; |
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doreadutmp(); |
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} |
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cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0); |
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if (cc <= 0) { |
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if (errno != EINTR) |
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sleep(1); |
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continue; |
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} |
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if (!nutmp) /* no one has logged in yet */ |
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continue; |
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sigemptyset(&sigset); |
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sigaddset(&sigset, SIGALRM); |
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sigprocmask(SIG_SETMASK, &sigset, NULL); |
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msgbuf[cc] = '\0'; |
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(void)time(&lastmsgtime); |
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mailfor(msgbuf); |
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sigemptyset(&sigset); |
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sigprocmask(SIG_SETMASK, &sigset, NULL); |
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} |
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} |
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/* ARGSUSED */ |
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void |
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reapchildren(int signo) |
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{ |
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int save_errno = errno; |
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while (wait3(NULL, WNOHANG, NULL) > 0) |
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; |
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errno = save_errno; |
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} |
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/* ARGSUSED */ |
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void |
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readutmp(int signo) |
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{ |
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wantreadutmp = 1; |
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} |
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void |
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doreadutmp(void) |
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{ |
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static u_int utmpsize; /* last malloced size for utmp */ |
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static time_t utmpmtime; /* last modification time for utmp */ |
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struct stat statbf; |
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int n; |
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if (time(NULL) - lastmsgtime >= MAXIDLE) |
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exit(0); |
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(void)fstat(uf, &statbf); |
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if (statbf.st_mtime > utmpmtime) { |
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utmpmtime = statbf.st_mtime; |
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/* avoid int overflow */ |
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if (statbf.st_size > INT_MAX - 10 * sizeof(struct utmp)) { |
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syslog(LOG_ALERT, "utmp file excessively large"); |
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exit(1); |
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} |
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if (statbf.st_size > utmpsize) { |
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u_int nutmpsize = statbf.st_size + 10 * |
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sizeof(struct utmp); |
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struct utmp *u; |
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if ((u = recallocarray(utmp, utmpsize, |
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nutmpsize, 1)) == NULL) { |
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free(utmp); |
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syslog(LOG_ERR, "%s", strerror(errno)); |
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exit(1); |
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} |
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utmp = u; |
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utmpsize = nutmpsize; |
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} |
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n = pread(uf, utmp, statbf.st_size, 0); |
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if (n == -1) |
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n = 0; |
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nutmp = n / sizeof(struct utmp); |
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dsyslog(LOG_DEBUG, "read %d utmp entries", nutmp); |
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} |
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(void)alarm(15); |
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} |
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void |
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mailfor(char *name) |
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{ |
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struct utmp *utp = &utmp[nutmp]; |
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char utname[UT_NAMESIZE+1]; |
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const char *errstr; |
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char *cp; |
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off_t offset; |
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dsyslog(LOG_DEBUG, "mail for '%s'", name); |
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if (!(cp = strchr(name, '@'))) |
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return; |
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*cp++ = '\0'; |
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cp[strcspn(cp, " \t\n")] = '\0'; |
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offset = strtonum(cp, 0, LLONG_MAX, &errstr); |
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if (errstr) { |
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syslog(LOG_ERR, "'%s' is %s", cp + 1, errstr); |
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return; |
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} |
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while (--utp >= utmp) { |
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memcpy(utname, utp->ut_name, UT_NAMESIZE); |
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utname[UT_NAMESIZE] = '\0'; |
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dsyslog(LOG_DEBUG, "check %s against %s", name, utname); |
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if (!strncmp(utname, name, UT_NAMESIZE)) |
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notify(utp, offset); |
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} |
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} |
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static char *cr; |
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void |
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notify(struct utmp *utp, off_t offset) |
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{ |
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int fd; |
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FILE *tp; |
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struct stat stb; |
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struct termios ttybuf; |
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char tty[PATH_MAX], name[UT_NAMESIZE + 1]; |
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(void)snprintf(tty, sizeof(tty), "%s%.*s", |
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_PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line); |
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if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) { |
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/* A slash is an attempt to break security... */ |
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syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty); |
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return; |
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} |
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if (stat(tty, &stb) || !(stb.st_mode & S_IEXEC)) { |
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dsyslog(LOG_DEBUG, "%.*s: wrong mode on %s", |
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(int)sizeof(utp->ut_name), utp->ut_name, tty); |
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return; |
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} |
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dsyslog(LOG_DEBUG, "notify %.*s on %s", (int)sizeof(utp->ut_name), |
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utp->ut_name, tty); |
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if (fork()) |
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return; |
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(void)signal(SIGALRM, SIG_DFL); |
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(void)alarm(30); |
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fd = open(tty, O_WRONLY); |
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if (fd == -1 || (tp = fdopen(fd, "w")) == NULL) { |
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dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno)); |
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_exit(1); |
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} |
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(void)tcgetattr(fileno(tp), &ttybuf); |
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cr = (ttybuf.c_oflag & ONLCR) && (ttybuf.c_oflag & OPOST) ? |
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"\n" : "\n\r"; |
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memcpy(name, utp->ut_name, UT_NAMESIZE); |
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name[UT_NAMESIZE] = '\0'; |
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(void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived:%s----%s", |
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cr, name, (int)sizeof(hostname), hostname, cr, cr); |
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jkfprintf(tp, name, offset); |
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(void)fclose(tp); |
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_exit(0); |
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} |
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void |
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jkfprintf(FILE *tp, char name[], off_t offset) |
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{ |
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char *cp, ch; |
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char visout[5], *s2; |
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FILE *fi; |
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int linecnt, charcnt, inheader; |
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char line[BUFSIZ]; |
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if ((fi = fopen(name, "r")) == NULL) |
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return; |
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(void)fseeko(fi, offset, SEEK_SET); |
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/* |
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* Print the first 7 lines or 560 characters of the new mail |
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* (whichever comes first). Skip header crap other than |
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* From, Subject, To, and Date. |
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*/ |
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linecnt = 7; |
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charcnt = 560; |
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inheader = 1; |
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while (fgets(line, sizeof(line), fi) != NULL) { |
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if (inheader) { |
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if (line[0] == '\n') { |
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inheader = 0; |
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continue; |
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} |
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if (line[0] == ' ' || line[0] == '\t' || |
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(strncmp(line, "From:", 5) && |
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strncmp(line, "Subject:", 8))) |
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continue; |
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} |
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if (linecnt <= 0 || charcnt <= 0) { |
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(void)fprintf(tp, "...more...%s", cr); |
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(void)fclose(fi); |
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return; |
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} |
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/* strip weird stuff so can't trojan horse stupid terminals */ |
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for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) { |
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ch = toascii(ch); |
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vis(visout, ch, VIS_SAFE|VIS_NOSLASH, cp[1]); |
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for (s2 = visout; *s2; s2++) |
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(void)fputc(*s2, tp); |
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} |
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(void)fputs(cr, tp); |
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--linecnt; |
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} |
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(void)fprintf(tp, "----%s\n", cr); |
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(void)fclose(fi); |
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} |