OpenBSD-4.6/libexec/comsat/comsat.c
/* $OpenBSD: comsat.c,v 1.35 2006/08/17 23:52:06 ray 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.
*/
#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1980, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
/*static char sccsid[] = "from: @(#)comsat.c 8.1 (Berkeley) 6/4/93";*/
static char rcsid[] = "$OpenBSD: comsat.c,v 1.35 2006/08/17 23:52:06 ray Exp $";
#endif /* not lint */
#include <sys/limits.h>
#include <sys/param.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 <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>
int debug = 0;
#define dsyslog if (debug) syslog
#define MAXIDLE 120
char hostname[MAXHOSTNAMELEN];
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);
}
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, 0)) == -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);
}
}
/* ARGSUSED */
void
reapchildren(int signo)
{
int save_errno = errno;
while (wait3(NULL, WNOHANG, NULL) > 0)
;
errno = save_errno;
}
/* ARGSUSED */
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;
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 = realloc(utmp, nutmpsize)) == NULL) {
free(utmp);
syslog(LOG_ERR, "%s", strerror(errno));
exit(1);
}
utmp = u;
utmpsize = nutmpsize;
}
(void)lseek(uf, 0, SEEK_SET);
nutmp = read(uf, utmp, statbf.st_size)/sizeof(struct utmp);
}
(void)alarm(15);
}
void
mailfor(char *name)
{
struct utmp *utp = &utmp[nutmp];
char utname[UT_NAMESIZE+1];
char *cp;
off_t offset;
if (!(cp = strchr(name, '@')))
return;
*cp = '\0';
offset = atoi(cp + 1);
while (--utp >= utmp) {
memcpy(utname, utp->ut_name, UT_NAMESIZE);
utname[UT_NAMESIZE] = '\0';
if (!strncmp(utname, name, UT_NAMESIZE))
notify(utp, offset);
}
}
static char *cr;
void
notify(struct utmp *utp, off_t offset)
{
FILE *tp;
struct stat stb;
struct termios ttybuf;
char tty[MAXPATHLEN], 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);
if ((tp = fopen(tty, "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;
struct passwd *p;
char line[BUFSIZ];
/* Set effective uid to user in case mail drop is on nfs */
if ((p = getpwnam(name)) != NULL) {
(void) seteuid(p->pw_uid);
(void) setuid(p->pw_uid);
}
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);
}