commands/telnetd/wtmp.c

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