2021-10-11 18:37:13 -03:00

310 lines
6.6 KiB
C

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1980 Regents of the University of California.\n\
All rights reserved.\n";
#endif not lint
#ifndef lint
static char *sccsid = "@(#)in.comsat.c 1.1 94/10/31 SMI"; /* from UCB 5.5 10/24/85 */
#endif not lint
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sgtty.h>
#include <utmp.h>
#include <signal.h>
#include <errno.h>
#include <netdb.h>
#include <syslog.h>
#include <pwd.h>
/*
* comsat
*/
int debug = 0;
#define dprintf if (debug) printf
struct sockaddr_in sin = { AF_INET };
extern errno;
char hostname[MAXHOSTNAMELEN];
struct utmp *utmp = NULL;
int nutmp;
int uf;
unsigned utmpmtime = 0; /* last modification time for utmp */
unsigned utmpsize = 0; /* last malloced size for utmp */
int onalrm();
int reapchildren();
long lastmsgtime;
char *malloc(), *realloc();
int maxidle = 120;
main(argc, argv)
int argc;
char *argv[];
{
register int cc;
char msgbuf[BUFSIZ];
struct sockaddr_in from;
int fromlen;
if (argc > 1)
maxidle = atoi(argv[1]);
/* verify proper invocation */
fromlen = sizeof (from);
if (getsockname(0, &from, &fromlen) < 0) {
fprintf(stderr, "%s: ", argv[0]);
perror("getsockname");
_exit(1);
}
chdir("/var/spool/mail");
if ((uf = open("/etc/utmp",0)) < 0) {
openlog("comsat", 0, LOG_DAEMON);
syslog(LOG_ERR, "/etc/utmp: %m");
(void) recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
exit(1);
}
lastmsgtime = time(0);
gethostname(hostname, sizeof (hostname));
onalrm();
signal(SIGALRM, onalrm);
signal(SIGTTOU, SIG_IGN);
signal(SIGCHLD, reapchildren);
for (;;) {
cc = recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
if (cc <= 0) {
if (errno != EINTR)
sleep(1);
errno = 0;
continue;
}
if (nutmp == 0) /* no users (yet) */
continue;
sigblock(sigmask(SIGALRM));
msgbuf[cc] = 0;
lastmsgtime = time(0);
mailfor(msgbuf);
sigsetmask(0);
}
}
reapchildren()
{
while (wait3((struct wait *)0, WNOHANG, (struct rusage *)0) > 0)
;
}
onalrm()
{
struct stat statbf;
if (time(0) - lastmsgtime >= maxidle)
exit(0);
dprintf("alarm\n");
alarm(15);
fstat(uf, &statbf);
if (statbf.st_mtime > utmpmtime) {
dprintf(" changed\n");
utmpmtime = statbf.st_mtime;
if (statbf.st_size > utmpsize) {
utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
if (utmp)
utmp = (struct utmp *)realloc(utmp, utmpsize);
else
utmp = (struct utmp *)malloc(utmpsize);
if (! utmp) {
dprintf("malloc failed\n");
exit(1);
}
}
lseek(uf, 0, 0);
nutmp = read(uf,utmp,statbf.st_size)/sizeof(struct utmp);
} else
dprintf(" ok\n");
}
mailfor(name)
char *name;
{
register struct utmp *utp = &utmp[nutmp];
register char *cp;
char *rindex();
int offset;
/*
* Don't bother doing anything if nobody has every
* logged into the system.
*/
if (utmp == NULL || nutmp == 0)
return;
dprintf("mailfor %s\n", name);
cp = name;
while (*cp && *cp != '@')
cp++;
if (*cp == 0) {
dprintf("bad format\n");
return;
}
*cp = 0;
offset = atoi(cp+1);
while (--utp >= utmp)
if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
notify(utp, offset);
}
char *cr;
notify(utp, offset)
register struct utmp *utp;
{
FILE *tp;
struct sgttyb gttybuf;
char tty[20], name[sizeof (utmp[0].ut_name) + 1];
struct stat stb;
time_t timep[2];
struct passwd *pwd;
int fd;
strcpy(tty, "/dev/");
strncat(tty, utp->ut_line, sizeof(utp->ut_line));
dprintf("notify %s on %s\n", utp->ut_name, tty);
if (stat(tty, &stb) == 0 && (stb.st_mode & 0100) == 0) {
dprintf("wrong mode\n");
return;
}
if (fork())
return;
signal(SIGALRM, SIG_DFL);
alarm(30);
/*
* Do all operations that check protections as the user who
* will be getting the biff.
*/
strncpy(name, utp->ut_name, sizeof (utp->ut_name));
name[sizeof (name) -1] = '\0';
if ((pwd = getpwnam(name)) == (struct passwd *) NULL) {
dprintf("getpwnam failed\n");
exit(1);
}
if (setuid(pwd->pw_uid) == -1) {
dprintf("setuid failed\n");
exit(1);
}
/*
* For the case where the user getting the biff is root,
* we need to make sure that the tty we will be sending
* the biff to is also owned by root.
* - bugid 1140162
*/
if (stb.st_uid != pwd->pw_uid) {
dprintf("tty is not owned by user getting the biff\n");
exit(1);
}
/*
* We need to make sure that the tty listed in the utmp
* file really is a tty device so that a corrupted utmp
* file doesn't cause us to over-write a real file.
*/
if ((fd = open (tty, O_RDWR)) == -1) {
dprintf("comsat: can't open tty\n");
exit(1);
}
if (isatty(fd) == 0) {
dprintf("comsat: line listed in utmp file is not a tty!!!\n");
exit(1);
}
(void) close(fd);
if ((tp = fopen(tty,"w")) == 0) {
dprintf("fopen failed\n");
exit(-1);
}
ioctl(fileno(tp), TIOCGETP, &gttybuf);
cr = (gttybuf.sg_flags&CRMOD) && !(gttybuf.sg_flags&RAW) ? "" : "\r";
fprintf(tp,"%s\n\007New mail for %s@%.*s\007 has arrived:%s\n",
cr, name, sizeof (hostname), hostname, cr);
fprintf(tp,"----%s\n", cr);
stat(name, &stb);
timep[0] = stb.st_atime;
timep[1] = stb.st_mtime;
jkfprintf(tp, name, offset);
utime(name, timep);
exit(0);
}
jkfprintf(tp, name, offset)
register FILE *tp;
{
register FILE *fi;
register int linecnt, charcnt;
char line[BUFSIZ];
int inheader;
dprintf("HERE %s's mail starting at %d\n",
name, offset);
if ((fi = fopen(name,"r")) == NULL) {
dprintf("Cant read the mail\n");
return;
}
fseek(fi, offset, L_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) {
register char *cp;
char *index();
int cnt;
if (linecnt <= 0 || charcnt <= 0) {
fprintf(tp,"...more...%s\n", cr);
return;
}
if (strncmp(line, "From ", 5) == 0)
continue;
if (inheader && (line[0] == ' ' || line[0] == '\t'))
continue;
cp = index(line, ':');
if (cp == 0 || (index(line, ' ') && index(line, ' ') < cp))
inheader = 0;
else
cnt = cp - line;
if (inheader &&
strncmp(line, "Date", cnt) &&
strncmp(line, "From", cnt) &&
strncmp(line, "Subject", cnt) &&
strncmp(line, "To", cnt))
continue;
cp = index(line, '\n');
if (cp)
*cp = '\0';
fprintf(tp,"%s%s\n", line, cr);
linecnt--, charcnt -= strlen(line);
}
fprintf(tp,"----%s\n", cr);
}