1 | /*
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2 | * TNET A server program for MINIX which implements the TCP/IP
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3 | * suite of networking protocols. It is based on the
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4 | * TCP/IP code written by Phil Karn et al, as found in
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5 | * his NET package for Packet Radio communications.
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6 | *
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7 | * This file contains an implementation of the "server"
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8 | * for the TELNET protocol. This protocol can be used to
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9 | * remote-login on other systems, just like a normal TTY
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10 | * session.
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11 | *
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12 | * Usage: telnetd [-dv]
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13 | *
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14 | * Version: @(#)telnetd.c 1.00 07/26/92
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15 | *
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16 | * Author: Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
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17 | * Michael Temari, <temari@temari.ae.ge.com>
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18 | */
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19 | #include <sys/types.h>
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20 | #include <fcntl.h>
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21 | #include <errno.h>
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22 | #include <stdlib.h>
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23 | #include <string.h>
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24 | #include <unistd.h>
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25 | #include <utmp.h>
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26 | #include <time.h>
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27 | #include <stdio.h>
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28 | #include "telnetd.h"
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29 |
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30 | static char PATH_UTMP[] = "/etc/utmp";
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31 | static char PATH_WTMP[] = "/usr/adm/wtmp";
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32 |
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33 | _PROTOTYPE(void wtmp, (int type, int linenr, char *line, pid_t pid,
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34 | char *host));
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35 | _PROTOTYPE(void report, (char *label));
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36 |
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37 | void wtmp(type, linenr, line, pid, host)
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38 | int type; /* type of entry */
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39 | int linenr; /* line number in ttytab */
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40 | char *line; /* tty name (only good on login) */
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41 | pid_t pid; /* pid of process */
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42 | char *host; /* name of the remote host */
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43 | {
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44 | /* Log an event into the UTMP and WTMP files. */
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45 |
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46 | struct utmp utmp; /* UTMP/WTMP User Accounting */
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47 | int fd;
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48 |
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49 | /* Clear the utmp record. */
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50 | memset((void *) &utmp, 0, sizeof(utmp));
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51 |
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52 | /* Fill in utmp. */
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53 | switch (type) {
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54 | case LOGIN_PROCESS:
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55 | /* A new login, fill in line and host name. */
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56 | strncpy(utmp.ut_line, line, sizeof(utmp.ut_line));
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57 | strncpy(utmp.ut_host, host, sizeof(utmp.ut_host));
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58 | break;
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59 |
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60 | case DEAD_PROCESS:
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61 | /* A logout. Use the current utmp entry, but make sure it is a
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62 | * user process exiting, and not getty or login giving up.
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63 | */
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64 | if ((fd = open(PATH_UTMP, O_RDONLY)) < 0) {
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65 | if (errno != ENOENT) report(PATH_UTMP);
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66 | return;
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67 | }
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68 | if (lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
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69 | || read(fd, &utmp, sizeof(utmp)) == -1
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70 | ) {
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71 | report(PATH_UTMP);
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72 | close(fd);
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73 | return;
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74 | }
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75 | close(fd);
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76 | if (utmp.ut_type != USER_PROCESS) return;
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77 | strncpy(utmp.ut_name, "", sizeof(utmp.ut_name));
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78 | break;
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79 | }
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80 |
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81 | /* Finish new utmp entry. */
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82 | utmp.ut_pid = pid;
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83 | utmp.ut_type = type;
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84 | utmp.ut_time = time((time_t *) 0);
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85 |
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86 | /* Write new entry to utmp. */
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87 | if ((fd = open(PATH_UTMP, O_WRONLY)) < 0
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88 | || lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
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89 | || write(fd, &utmp, sizeof(utmp)) == -1
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90 | ) {
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91 | if (errno != ENOENT) report(PATH_UTMP);
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92 | }
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93 | if (fd != -1) close(fd);
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94 |
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95 | if (type == DEAD_PROCESS) {
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96 | /* Add new wtmp entry. */
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97 | if ((fd = open(PATH_WTMP, O_WRONLY | O_APPEND)) < 0
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98 | || write(fd, &utmp, sizeof(utmp)) == -1
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99 | ) {
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100 | if (errno != ENOENT) report(PATH_WTMP);
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101 | }
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102 | if (fd != -1) close(fd);
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103 | }
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104 | }
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105 |
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106 | void report(label)
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107 | char *label;
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108 | {
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109 | char message[128];
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110 |
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111 | sprintf(message, "telnetd: %s: %s\r\n", strerror(errno));
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112 | (void) write(1, message, strlen(message));
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113 | }
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