usr/src/libexec/comsat/comsat.c

/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#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[] = "@(#)comsat.c    8.1 (Berkeley) %G%";
#endif /* not lint */

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/wait.h>

#include <netinet/in.h>

#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <paths.h>
#include <pwd.h>
#include <sgtty.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <utmp.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 __P((FILE *, char[], off_t));
void mailfor __P((char *));
void notify __P((struct utmp *, off_t));
void onalrm __P((int));
void reapchildren __P((int));

int
main(argc, argv)
        int argc;
        char *argv[];
{
        struct sockaddr_in from;
        register int cc;
        int fromlen;
        char msgbuf[100];

        /* verify proper invocation */
        fromlen = sizeof(from);
        if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0) {
                (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)) < 0) {
                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));
        onalrm(0);
        (void)signal(SIGALRM, onalrm);
        (void)signal(SIGTTOU, SIG_IGN);
        (void)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)             /* no one has logged in yet */
                        continue;
                sigblock(sigmask(SIGALRM));
                msgbuf[cc] = '\0';
                (void)time(&lastmsgtime);
                mailfor(msgbuf);
                sigsetmask(0L);
        }
}

void
reapchildren(signo)
        int signo;
{
        while (wait3(NULL, WNOHANG, NULL) > 0);
}

void
onalrm(signo)
        int signo;
{
        static u_int utmpsize;          /* last malloced size for utmp */
        static u_int utmpmtime;         /* last modification time for utmp */
        struct stat statbf;

        if (time(NULL) - lastmsgtime >= MAXIDLE)
                exit(0);
        (void)alarm((u_int)15);
        (void)fstat(uf, &statbf);
        if (statbf.st_mtime > utmpmtime) {
                utmpmtime = statbf.st_mtime;
                if (statbf.st_size > utmpsize) {
                        utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
                        if ((utmp = realloc(utmp, utmpsize)) == NULL) {
                                syslog(LOG_ERR, "%s", strerror(errno));
                                exit(1);
                        }
                }
                (void)lseek(uf, (off_t)0, L_SET);
                nutmp = read(uf, utmp, (int)statbf.st_size)/sizeof(struct utmp);
        }
}

void
mailfor(name)
        char *name;
{
        register struct utmp *utp = &utmp[nutmp];
        register char *cp;
        off_t offset;

        if (!(cp = strchr(name, '@')))
                return;
        *cp = '\0';
        offset = atoi(cp + 1);
        while (--utp >= utmp)
                if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
                        notify(utp, offset);
}

static char *cr;

void
notify(utp, offset)
        register struct utmp *utp;
        off_t offset;
{
        FILE *tp;
        struct stat stb;
        struct sgttyb gttybuf;
        char tty[20], name[sizeof(utmp[0].ut_name) + 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", utp->ut_name, tty);
                return;
        }
        dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
        if (fork())
                return;
        (void)signal(SIGALRM, SIG_DFL);
        (void)alarm((u_int)30);
        if ((tp = fopen(tty, "w")) == NULL) {
                dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
                _exit(-1);
        }
        (void)ioctl(fileno(tp), TIOCGETP, &gttybuf);
        cr = (gttybuf.sg_flags&CRMOD) && !(gttybuf.sg_flags&RAW) ?
            "\n" : "\n\r";
        (void)strncpy(name, utp->ut_name, sizeof(utp->ut_name));
        name[sizeof(name) - 1] = '\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(tp, name, offset)
        register FILE *tp;
        char name[];
        off_t offset;
{
        register char *cp, ch;
        register FILE *fi;
        register int linecnt, charcnt, inheader;
        register struct passwd *p;
        char line[BUFSIZ];

        /* Set effective uid to user in case mail drop is on nfs */
        if ((p = getpwnam(name)) != NULL)
                (void) setuid(p->pw_uid);

        if ((fi = fopen(name, "r")) == NULL)
                return;

        (void)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) {
                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);
                        if (!isprint(ch) && !isspace(ch))
                                ch |= 0x40;
                        (void)fputc(ch, tp);
                }
                (void)fputs(cr, tp);
                --linecnt;
        }
        (void)fprintf(tp, "----%s\n", cr);
        (void)fclose(fi);
}