source: trunk/athena/bin/write/write.c @ 497

/*
 *      $Source: /afs/dev.mit.edu/source/repository/athena/bin/write/write.c,v $
 *      $Header: /afs/dev.mit.edu/source/repository/athena/bin/write/write.c,v 1.4 1987-07-03 17:52:23 ens Exp $
 */

#ifndef lint
static char *rcsid_write_c = "$Header: /afs/dev.mit.edu/source/repository/athena/bin/write/write.c,v 1.4 1987-07-03 17:52:23 ens Exp $";
#endif lint

#ifndef lint
static char *sccsid = "@(#)write.c      4.13 3/13/86";
#endif
/*
 * write to another user
 */

#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <utmp.h>
#include <sys/time.h>
#include        <sys/socket.h>
#include        <netinet/in.h>
#include        <netdb.h>
#include <pwd.h>

#define NMAX    sizeof(ubuf.ut_name)
#define LMAX    sizeof(ubuf.ut_line)

char    *strcat();
char    *strcpy();
struct  utmp ubuf;
int     signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};
char    mebuf[NMAX + 1] = "???";
char    *me;
char    *him;
int     netme = 0;
int     nethim = 0;
char    *mytty;
char    histty[32];
char    ttybuf[32];
char    *histtya;
char    myhost[32];
char    *hishost;
struct hostent *hp;
struct servent *sp;
struct sockaddr_in sin;
int     fds;
char    buf[128];
struct passwd *pwdent;
FILE    *tf;
int     logcnt;
char    *ttyname();
char    *rindex();
int     eof();
int     timout();
char    *getenv();

main(argc, argv)
        int argc;
        char *argv[];
{
        struct stat stbuf;
        register i;
        register FILE *uf;
        int c1, c2;
        long clock = time(0);
        int suser = getuid() == 0;
        int nomesg = 0;
        struct tm *localtime();
        struct tm *localclock = localtime( &clock );

        me = mebuf;
        if ((argc > 3) && (getuid() == 0) &&
            (strcmp("-f", argv[1]) == 0) &&
            (mytty = rindex(argv[2], '@'))) {
                me = argv[2];
                *mytty++ = '\0';
                netme = 1;
                argc -= 2;
                argv += 2;
        }
        if (argc < 2 || argc > 3) {
                fprintf(stderr, "Usage: write user [ttyname]\n");
                exit(1);
        }
        him = argv[1];
        if ((!netme) && (hishost = rindex(him, '@'))) {
                *hishost++ = '\0';
                hp = gethostbyname(hishost);
                if (hp == NULL) {
                        static struct hostent def;
                        static struct in_addr defaddr;
                        static char namebuf[128];
                        int inet_addr();

                        defaddr.s_addr = inet_addr(hishost);
                        if (defaddr.s_addr == -1) {
                                printf("unknown host: %s\n", hishost);
                                exit(1);
                        }
                        strcpy(namebuf, hishost);
                        def.h_name = namebuf;
                        def.h_addr = (char *)&defaddr;
                        def.h_length = sizeof (struct in_addr);
                        def.h_addrtype = AF_INET;
                        def.h_aliases = 0;
                        hp = &def;
                }
                nethim = 1;
        }

        if (argc == 3)
                histtya = argv[2];
        if ((uf = fopen("/etc/utmp", "r")) == NULL) {
                perror("write: Can't open /etc/utmp");
                if (histtya == 0)
                        exit(10);
                goto cont;
        }
        if (!netme) {
            mytty = ttyname(2);
            if (mytty == NULL) {
                fprintf(stderr, "write: Can't find your tty\n");
                exit(1);
            }
            if (stat(mytty, &stbuf) < 0) {
                perror("write: Can't stat your tty");
                exit(1);
            }
            if ((stbuf.st_mode&020) == 0) {
                fprintf(stderr,
                        "write: You have write permission turned off\n");
                if (!suser)
                  exit(1);
            }
            mytty = rindex(mytty, '/') + 1;
        }
        if (histtya) {
                strcpy(histty, "/dev/");
                strcat(histty, histtya);
        }
        while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
                if (ubuf.ut_name[0] == '\0')
                        continue;
                if ((!netme) && strcmp(ubuf.ut_line, mytty)==0) {
                        for (i=0; i<NMAX; i++) {
                                c1 = ubuf.ut_name[i];
                                if (c1 == ' ')
                                        c1 = 0;
                                me[i] = c1;
                                if (c1 == 0)
                                        break;
                        }
                }
                if (nethim) goto nomat;
                if (him[0] == '-' && him[1] == 0)
                        goto nomat;
                for (i=0; i<NMAX; i++) {
                        c1 = him[i];
                        c2 = ubuf.ut_name[i];
                        if (c1 == 0)
                                if (c2 == 0 || c2 == ' ')
                                        break;
                        if (c1 != c2)
                                goto nomat;
                }
                if (histtya && strncmp(histtya, ubuf.ut_line,
                    sizeof(ubuf.ut_line)))
                        continue;
                logcnt++;
                if (histty[0]==0 || nomesg && histtya == 0) {
                        strcpy(ttybuf, "/dev/");
                        strcat(ttybuf, ubuf.ut_line);
                        if (histty[0]==0)
                                strcpy(histty, ttybuf);
                        if (access(ttybuf, 0) < 0 || stat(ttybuf, &stbuf) < 0 ||
                            (stbuf.st_mode&020) == 0)
                                nomesg++;
                        else {
                                strcpy(histty, ttybuf);
                                nomesg = 0;
                        }
                }
        nomat:
                ;
        }
        fclose(uf);
        if (!nethim) { 
            if (logcnt==0) {
                fprintf(stderr, "write: %s not logged in%s\n", him,
                        histtya ? " on that tty" : "");
                exit(1);
            }
            if (histtya==0 && logcnt > 1) {
                fprintf(stderr,
                        "write: %s logged in more than once ... writing to %s\n",
                        him, histty+5);
            }
        }
cont:
        fclose(uf);
        if((!netme) && (mebuf[0] == '?')) {
            pwdent = getpwuid(getuid());
            if (pwdent == NULL) {
                printf("You don't exist. Go away.\n");
                exit(-1);
            }
            strcpy(mebuf, pwdent->pw_name);
        }
        if (nethim) {
                sp = getservbyname("write", "tcp");
                if (sp == 0) {
                        printf("tcp/write: unknown service\n");
                        exit(1);
                }
                sin.sin_family = hp->h_addrtype;
                bcopy(hp->h_addr, (char *)&sin.sin_addr, hp->h_length);
                sin.sin_port = sp->s_port;
                fds = socket(hp->h_addrtype, SOCK_STREAM, 0);
                if (fds < 0) {
                        perror("socket");
                        exit(1);
                }
                if (connect(fds, (char *)&sin, sizeof (sin)) < 0) {
                        perror("connect");
                        close(fds);
                        exit(1);
                }

                write(fds, me, strlen(me));
                write(fds, "@", 1);
                gethostname(myhost, sizeof (myhost));
                write(fds, myhost, strlen(myhost));
                write(fds, " ", 1);
                write(fds, him, strlen(him));
                if (histtya) {
                        write(fds, " ", 1);
                        write(fds, histtya, strlen(histtya));
                }
                write(fds, "\r\n", 2);
                sigs(eof);
                tf = fdopen(fds, "r+");
                while (1) {
                        if (fgets(buf, sizeof(buf), tf) == NULL) exit(1);
                        if (buf[0] == '\n') break;
                        write(1, buf, strlen(buf));
                }
        } else {
            if (access(histty, 0) < 0) {
                fprintf(stderr, "write: No such tty\n");
                exit(1);
            }
            signal(SIGALRM, timout);
            alarm(5);
            if (setpgrp(0,0))
                 perror("setpgrp 0");
            if (stat(histty, &stbuf) < 0 || (stbuf.st_mode&020) == 0
                        || (tf = fopen(histty, "w")) == NULL) {
                fprintf(stderr, "write: Permission denied\n");
                exit(1);
            }
            if (setpgrp(0,getpid()))
                 perror("setpgrp !0");
            alarm(0);
            sigs(eof);
            if (netme) {
                printf("\n");
                fflush(stdout);
                fprintf(tf,
                 "\r\nMessage from %s on %s at %d:%02d ...\r\n\007\007\007",
                 me, mytty, localclock->tm_hour, localclock->tm_min);
            } else
            { char hostname[32];
              gethostname(hostname, sizeof (hostname));
              fprintf(tf,
                 "\r\nMessage from %s@%s on %s at %d:%02d ...\r\n\007\007\007",
                 me, hostname, mytty, localclock->tm_hour, localclock->tm_min);
            }
            fflush(tf);
            fds = fileno(tf);
        }
        for (;;) {
                char buf[BUFSIZ];
                register char *bp;
                i = read(0, buf, sizeof buf);
                if (i <= 0)
                        eof();
                if ((!netme) && buf[0] == '!') {
                        buf[i] = 0;
                        ex(buf);
                        continue;
                }
                for (bp = buf; --i >= 0; bp++) {
                        if (*bp == '\n')
                                putc('\r', tf);

                        if (!isascii(*bp)) {
                                putc('M', tf);
                                putc('-', tf);
                                *bp = toascii(*bp);
                        }

                        if (isprint(*bp) ||
                            *bp == ' ' || *bp == '\t' || *bp == '\n'
                            || *bp == '\r') {
                                putc(*bp, tf);
                        } else {
                                putc('^', tf);
                                putc(*bp ^ 0100, tf);
                        }

                        if (*bp == '\n')
                                fflush(tf);

                        if (ferror(tf) || feof(tf)) {
                                printf("\n\007Write failed (%s logged out?)\n",
                                        him);
                                exit(1);
                        }
                }
        }
}

timout()
{

        fprintf(stderr, "write: Timeout opening their tty\n");
        exit(1);
}

eof()
{

        if (!nethim) {
            fprintf(tf, "EOF\r\n");
            fflush(tf);
        }
        exit(0);
}

ex(bp)
        char *bp;
{
        register i;

        sigs(SIG_IGN);
        i = fork();
        if (i < 0) {
                printf("Try again\n");
                goto out;
        }
        if (i == 0) {
                fclose(tf);             /* Close his terminal */
                setgid(getgid());       /* Give up effective group privs */
                sigs((int (*)())0);
                execl(getenv("SHELL") ?
                    getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);
                exit(0);
        }
        while (wait((int *)NULL) != i)
                ;
        printf("!\n");
out:
        sigs(eof);
}

sigs(sig)
        int (*sig)();
{
        register i;

        for (i=0; signum[i]; i++)
                signal(signum[i], sig);
}