Initial revision

commands/telnetd/Makefile

@@ -0,0 +1,31 @@
+# Makefile for telnetd
+#
+# 01/30/96 Initial Release	Michael Temari, <temari@ix.netcom.com>
+#
+
+CFLAGS=	-O -D_MINIX -D_POSIX_SOURCE
+LDFLAGS=-i
+BINDIR=	/usr/bin
+PROG=	in.telnetd
+
+OBJS=	main.o telnet.o term.o pty.o wtmp.o
+
+all:	$(PROG)
+
+$(PROG):	$(OBJS)
+	$(CC) $(LDFLAGS) -o $@ $(OBJS)
+	install -S 8kw $@
+
+clean:
+	rm -f $(PROG) $(OBJS)
+
+install:	$(BINDIR)/$(PROG)
+
+$(BINDIR)/$(PROG):	$(PROG)
+	install -cs -o bin $? $@
+
+main.o:		main.c		telnetd.h
+telnet.o:	telnet.c	telnetd.h	telnet.h
+term.o:		term.c		telnetd.h	telnet.h
+pty.o:		pty.c		telnetd.h
+wtmp.o:				telnetd.h

commands/telnetd/main.c

@@ -0,0 +1,158 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		This file contains an implementation of the "server"
+ *		for the TELNET protocol.  This protocol can be used to
+ *		remote-login on other systems, just like a normal TTY
+ *		session.
+ *
+ * Usage:	telnetd [-dv]
+ *
+ * Version:	@(#)telnetd.c	1.00	07/26/92
+ *
+ * Author:	Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ *		Michael Temari, <temari@temari.ae.ge.com>
+ */
+#include <sys/types.h>
+#include <fcntl.h>
+#include <sys/wait.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <time.h>
+#include <stdio.h>
+#include <ttyent.h>
+#include <utmp.h>
+#include <net/gen/in.h>
+#include <net/gen/tcp.h>
+#include <net/gen/tcp_io.h>
+#include <net/gen/socket.h>
+#include <net/gen/netdb.h>
+#include <net/gen/inet.h>
+#include "telnetd.h"
+
+static char *Version = "@(#) telnetd 1.00 (07/26/92)";
+
+int opt_d = 0;				/* debugging output flag	*/
+
+_PROTOTYPE(void usage, (void));
+_PROTOTYPE(int main, (int argc, char *argv[]));
+_PROTOTYPE(void wtmp, (int type, int linenr, char *line, pid_t pid,
+								char *host));
+
+void usage()
+{
+   fprintf(stderr, "Usage: telnetd [-dv]\n");
+
+   exit(-1);
+}
+
+int main(argc, argv)
+int argc;
+char *argv[];
+{
+char buff[128];
+register int c;
+int pty_fd;
+int tty_fd;
+pid_t pid;
+int lineno;
+char *tty_name;
+struct ttyent *ttyp;
+nwio_tcpconf_t tcpconf;
+struct hostent *hostent;
+char *hostname;
+
+   opterr = 0;
+   while ((c = getopt(argc, argv, "dv")) != EOF) switch(c) {
+	case 'd':
+	case 'v':
+		opt_d = 1;
+		break;
+	default:
+		usage();
+   }
+
+   /* No more arguments allowed. */
+   if (optind != argc) usage();
+
+   /* Obtain the name of the remote host. */
+   if (ioctl(0, NWIOGTCPCONF, &tcpconf) < 0) {
+	sprintf(buff, "Unable to obtain your IP address\r\n");
+	(void) write(1, buff, strlen(buff));
+	return(-1);
+   }
+   if ((hostent = gethostbyaddr((char *) &tcpconf.nwtc_remaddr,
+			sizeof(tcpconf.nwtc_remaddr), AF_INET)) != NULL) {
+	hostname = hostent->h_name;
+   } else {
+	hostname = inet_ntoa(tcpconf.nwtc_remaddr);
+   }
+
+   /* Try allocating a PTY. */
+   if (get_pty(&pty_fd, &tty_name) < 0) {
+	sprintf(buff, "I am sorry, but there is no free PTY left!\r\n");
+	(void) write(1, buff, strlen(buff));
+	return(-1);
+   }
+
+   /* Find the tty in the tty table. */
+   lineno = 0;
+   for (;;) {
+	if ((ttyp = getttyent()) == NULL) {
+		sprintf(buff, "Can't find %s in the tty table\r\n");
+		(void) write(1, buff, strlen(buff));
+	}
+	if (strcmp(ttyp->ty_name, tty_name+5) == 0) break;
+	lineno++;
+   }
+   endttyent();
+
+   /* Initialize the connection to an 8 bit clean channel. */
+   term_init();
+
+   /* Fork off a child process and have it execute a getty(8). */
+   if ((pid = fork()) == 0) {
+	/* Set up a new session. */
+	setsid();
+	if ((tty_fd = open(tty_name, O_RDWR)) < 0) {
+		sprintf(buff, "Can't open %s\r\n", tty_name);
+		(void) write(1, buff, strlen(buff));
+		return(-1);
+	}
+
+	close(pty_fd);
+	dup2(tty_fd, 0);
+	dup2(tty_fd, 1);
+	dup2(tty_fd, 2);
+	close(tty_fd);
+	(void) execl("/usr/sbin/getty", "getty", (char *)NULL);
+	(void) execl("/usr/bin/getty", "getty", (char *)NULL);
+	(void) execl("/usr/bin/login", "login", (char *)NULL);
+	(void) write(1, "EXEC failed!\r\n", 14);
+   } else if (pid < 0) {
+	sprintf(buff, "I am sorry, but the fork(2) call failed!\r\n");
+	(void) write(1, buff, strlen(buff));
+	(void) close(pty_fd);
+	return(-1);
+   }
+
+   wtmp(LOGIN_PROCESS, lineno, tty_name+5, pid, hostname);
+
+   term_inout(pty_fd);
+
+   (void) close(pty_fd);
+
+   wtmp(DEAD_PROCESS, lineno, tty_name+5, pid, hostname);
+
+   chown(tty_name, 0, 0);
+   chmod(tty_name, 0666);
+
+   return(0);
+}

commands/telnetd/pty.c

@@ -0,0 +1,78 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		Handle the allocation of a PTY.
+ *
+ * Author:	Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ */
+#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include "telnetd.h"
+
+
+#define DEV_DIR		"/dev"
+
+/*
+ * Allocate a PTY, by trying to open one repeatedly,
+ * until all PTY channels are done.  If at that point
+ * no PTY is found, go into panic mode :-(
+ */
+int get_pty(pty_fdp, tty_namep)
+int *pty_fdp;
+char **tty_namep;
+{
+  char buff[128], temp[128];
+  register int i, j;
+  int pty_fd;
+  static char tty_name[128];
+
+  for(i = 'p'; i < 'w'; i++) {
+	j = 0;
+	do {
+		sprintf(buff, "%s/pty%c%c",
+			DEV_DIR, i, (j < 10) ? j + '0' : j + 'a' - 10);
+
+		if (opt_d == 1) {
+			(void) write(2, "Testing: ", 9);
+			(void) write(2, buff, strlen(buff));
+			(void) write(2, "...: ", 5);
+		}
+
+		pty_fd = open(buff, O_RDWR);
+		if (opt_d == 1) {
+			if (pty_fd < 0) sprintf(temp, "error %d\r\n", errno);
+			  else sprintf(temp, "OK\r\n");
+			(void) write(2, temp, strlen(temp));
+		}
+
+		if (pty_fd >= 0) break;
+
+		j++;
+		if (j == 16) break;
+	} while(1);
+
+	/* Did we find one? */
+	if (j < 16) break;
+  }
+  if (pty_fd < 0) return(-1);
+
+  if (opt_d == 1) {
+	sprintf(temp, "File %s, desc %d\n", buff, pty_fd);
+	(void) write(1, temp, strlen(temp));
+  }
+
+  sprintf(tty_name, "%s/tty%c%c", DEV_DIR,
+  					i, (j < 10) ? j + '0' : j + 'a' - 10);
+
+  *pty_fdp = pty_fd;
+  *tty_namep = tty_name;
+  return(0);
+}

commands/telnetd/telnet.c

@@ -0,0 +1,263 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		This module handles telnet option processing.
+ *
+ * Author:	Michael Temari, <temari@temari.ae.ge.com>  01/13/93
+ *
+ */
+#include <sys/types.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "telnetd.h"
+#include "telnet.h"
+#include <stdio.h>
+
+#define	IN_DATA	0
+#define	IN_CR	1
+#define	IN_IAC	2
+#define	IN_IAC2	3
+
+_PROTOTYPE(static void dowill, (int c));
+_PROTOTYPE(static void dowont, (int c));
+_PROTOTYPE(static void dodo, (int c));
+_PROTOTYPE(static void dodont, (int c));
+_PROTOTYPE(static void respond, (int ack, int option));
+
+#define	LASTTELOPT	TELOPT_SGA
+
+static int TelROpts[LASTTELOPT+1];
+static int TelLOpts[LASTTELOPT+1];
+
+static int telfdout;
+
+void tel_init()
+{
+int i;
+
+   for(i = 0; i <= LASTTELOPT; i++) {
+	TelROpts[i] = 0;
+	TelLOpts[i] = 0;
+   }
+}
+
+void telopt(fdout, what, option)
+int fdout;
+int what;
+int option;
+{
+char buf[3];
+int len;
+
+   buf[0] = IAC;
+   buf[1] = what;
+   buf[2] = option;
+   len = 0;
+
+   switch(what) {
+	case DO:
+		if(option <= LASTTELOPT) {
+			TelROpts[option] = 1;
+			len = 3;
+		}
+		break;
+	case DONT:
+		if(option <= LASTTELOPT) {
+			TelROpts[option] = 1;
+			len = 3;
+		}
+		break;
+	case WILL:
+		if(option <= LASTTELOPT) {
+			TelLOpts[option] = 1;
+			len = 3;
+		}
+		break;
+	case WONT:
+		if(option <= LASTTELOPT) {
+			TelLOpts[option] = 1;
+			len = 3;
+		}
+		break;
+   }
+   if(len > 0)
+	(void) write(fdout, buf, len);
+}
+
+int tel_in(fdout, telout, buffer, len)
+int fdout;
+int telout;
+char *buffer;
+int len;
+{
+static int InState = IN_DATA;
+static int ThisOpt = 0;
+char *p;
+char *p2;
+int size;
+int c;
+
+   telfdout = telout;
+   p = p2 = buffer;
+   size = 0;
+
+   while(len > 0) {
+   	c = (unsigned char)*p++; len--;
+	switch(InState) {
+   		case IN_CR:
+   			InState = IN_DATA;
+   			if(c == 0 || c == '\n')
+   				break;
+   			/* fall through */
+   		case IN_DATA:
+   			if(c == IAC) {
+   				InState = IN_IAC;
+   				break;
+   			}
+   			*p2++ = c; size++;
+   			if(c == '\r') InState = IN_CR;
+   			break;
+   		case IN_IAC:
+   			switch(c) {
+   				case IAC:
+	   				*p2++ = c; size++;
+   					InState = IN_DATA;
+   					break;
+   				case WILL:
+   				case WONT:
+   				case DO:
+   				case DONT:
+   					InState = IN_IAC2;
+   					ThisOpt = c;
+   					break;
+   				case EOR:
+   				case SE:
+   				case NOP:
+   				case BREAK:
+   				case IP:
+   				case AO:
+   				case AYT:
+   				case EC:
+   				case EL:
+   				case GA:
+   				case SB:
+   					break;
+   				default:
+   					break;
+   			}
+   			break;
+   		case IN_IAC2:
+   			if(size > 0) {
+   				write(fdout, buffer, size);
+   				p2 = buffer;
+   				size = 0;
+   			}
+   			InState = IN_DATA;
+   			switch(ThisOpt) {
+   				case WILL:	dowill(c);	break;
+   				case WONT:	dowont(c);	break;
+   				case DO:	dodo(c);	break;
+   				case DONT:	dodont(c);	break;
+   			}
+   			break;
+   	}
+   }
+
+   if(size > 0)
+   	write(fdout, buffer, size);
+}
+
+int tel_out(fdout, buf, size)
+int fdout;
+char *buf;
+int size;
+{
+char *p;
+int got_iac, len;
+
+   p = buf;
+   while(size > 0) {
+	buf = p;
+	got_iac = 0;
+	if((p = (char *)memchr(buf, IAC, size)) != (char *)NULL) {
+		got_iac = 1;
+		p++;
+	} else
+		p = buf + size;
+	len = p - buf;
+	if(len > 0)
+		(void) write(fdout, buf, len);
+	if(got_iac)
+		(void) write(fdout, p - 1, 1);
+	size = size - len;
+   }
+}
+
+static void dowill(c)
+int c;
+{
+int ack;
+
+   switch(c) {
+	case TELOPT_BINARY:
+	case TELOPT_ECHO:
+	case TELOPT_SGA:
+		if(TelROpts[c] == 1)
+			return;
+		TelROpts[c] = 1;
+		ack = DO;
+		break;
+	default:
+		ack = DONT;
+   }
+   respond(ack, c);
+}
+
+static void dowont(c)
+int c;
+{
+   if(c <= LASTTELOPT) {
+	if(TelROpts[c] == 0)
+		return;
+	TelROpts[c] = 0;
+   }
+   respond(DONT, c);
+}
+
+static void dodo(c)
+int c;
+{
+int ack;
+
+   switch(c) {
+	default:
+		ack = WONT;
+   }
+   respond(ack, c);
+}
+
+static void dodont(c)
+int c;
+{
+   if(c <= LASTTELOPT) {
+	if(TelLOpts[c] == 0)
+		return;
+	TelLOpts[c] = 0;
+   }
+   respond(WONT, c);
+}
+
+static void respond(ack, option)
+int ack, option;
+{
+unsigned char c[3];
+
+   c[0] = IAC;
+   c[1] = ack;
+   c[2] = option;
+   /* write(telfdout, c, 3); */
+}

commands/telnetd/telnet.h

@@ -0,0 +1,70 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ * 		Definitions for the TELNET protocol (see RFC XXX).
+ *
+ * Version:	@(#)arpa/telnet.h	1.00		07/02/92
+ *
+ * Authors:	Original taken from BSD 4.3/TAHOE.
+ *		Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ */
+#ifndef _ARPA_TELNET_H
+#define _ARPA_TELNET_H
+
+#define	IAC		255	/* interpret as command:		*/
+#define	DONT		254	/* you are not to use option		*/
+#define	DO		253	/* please, you use option		*/
+#define	WONT		252	/* I won't use option			*/
+#define	WILL		251	/* I will use option			*/
+#define	SB		250	/* interpret as subnegotiation		*/
+#define	GA		249	/* you may reverse the line		*/
+#define	EL		248	/* erase the current line		*/
+#define	EC		247	/* erase the current character		*/
+#define	AYT		246	/* are you there			*/
+#define	AO		245	/* abort output--but let prog finish	*/
+#define	IP		244	/* interrupt process--permanently	*/
+#define	BREAK		243	/* break				*/
+#define	DM		242	/* data mark--for connect. cleaning	*/
+#define	NOP		241	/* nop					*/
+#define	SE		240	/* end sub negotiation			*/
+#define EOR     	239     /* end of record (transparent mode)	*/
+
+#define SYNCH		242	/* for telfunc calls			*/
+
+/* Telnet options. */
+#define TELOPT_BINARY	0	/* 8-bit data path			*/
+#define TELOPT_ECHO	1	/* echo					*/
+#define	TELOPT_RCP	2	/* prepare to reconnect			*/
+#define	TELOPT_SGA	3	/* suppress go ahead			*/
+#define	TELOPT_NAMS	4	/* approximate message size		*/
+#define	TELOPT_STATUS	5	/* give status				*/
+#define	TELOPT_TM	6	/* timing mark				*/
+#define	TELOPT_RCTE	7	/* remote controlled transmission and echo */
+#define TELOPT_NAOL 	8	/* negotiate about output line width	*/
+#define TELOPT_NAOP 	9	/* negotiate about output page size	*/
+#define TELOPT_NAOCRD	10	/* negotiate about CR disposition	*/
+#define TELOPT_NAOHTS	11	/* negotiate about horizontal tabstops	*/
+#define TELOPT_NAOHTD	12	/* negotiate about horizontal tab disposition */
+#define TELOPT_NAOFFD	13	/* negotiate about formfeed disposition	*/
+#define TELOPT_NAOVTS	14	/* negotiate about vertical tab stops	*/
+#define TELOPT_NAOVTD	15	/* negotiate about vertical tab disposition */
+#define TELOPT_NAOLFD	16	/* negotiate about output LF disposition */
+#define TELOPT_XASCII	17	/* extended ascic character set		*/
+#define	TELOPT_LOGOUT	18	/* force logout				*/
+#define	TELOPT_BM	19	/* byte macro				*/
+#define	TELOPT_DET	20	/* data entry terminal			*/
+#define	TELOPT_SUPDUP	21	/* supdup protocol			*/
+#define	TELOPT_SUPDUPOUTPUT 22	/* supdup output			*/
+#define	TELOPT_SNDLOC	23	/* send location			*/
+#define	TELOPT_TTYPE	24	/* terminal type			*/
+#define	TELOPT_EOR	25	/* end or record			*/
+#define TELOPT_EXOPL	255	/* extended-options-list		*/
+
+/* Sub-option qualifiers. */
+#define	TELQUAL_IS	0	/* option is...				*/
+#define	TELQUAL_SEND	1	/* send option				*/
+
+#endif /* _ARPA_TELNET_H */

commands/telnetd/telnetd.h

@@ -0,0 +1,20 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		Definitions for the TELNET server.
+ *
+ * Author:	Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ */
+
+extern int opt_d;			/* debugging flag		*/
+
+_PROTOTYPE(int get_pty, (int *, char **));
+_PROTOTYPE(void term_init, (void));
+_PROTOTYPE(void term_inout, (int pty_fd));
+_PROTOTYPE(void tel_init, (void));
+_PROTOTYPE(void telopt, (int fdout, int what, int option));
+_PROTOTYPE(int tel_in, (int fdout, int telout, char *buffer, int len));
+_PROTOTYPE(int tel_out, (int fdout, char *buf, int size));

commands/telnetd/term.c

@@ -0,0 +1,85 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		Handle the TERMINAL module.
+ *
+ * Author:	Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ *              Michael Temari, <temari@temari.ae.ge.com>
+ *
+ * 07/29/92 MT  Telnet options hack which seems to work okay
+ * 01/12/93 MT  Better telnet options processing instead of hack
+ */
+#include <sys/types.h>
+#include <errno.h>
+#if 0
+#include <fcntl.h>
+#endif
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include "telnet.h"
+#include "telnetd.h"
+
+_PROTOTYPE(void sig_done, (int sig));
+
+static char buff[4096];
+
+void term_init()
+{
+  tel_init();
+
+  telopt(1, WILL, TELOPT_SGA);
+  telopt(1, DO,   TELOPT_SGA);
+  telopt(1, WILL, TELOPT_BINARY);
+  telopt(1, DO,   TELOPT_BINARY);
+  telopt(1, WILL, TELOPT_ECHO);
+}
+
+static int io_done = 0;
+
+void term_inout(pty_fd)
+int pty_fd;
+{
+register int i;
+pid_t pid;
+struct sigaction sa;
+
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = 0;
+  sa.sa_handler = sig_done;
+  sigaction(SIGALRM, &sa, (struct sigaction *) NULL);
+
+  if ((pid = fork()) == -1) {
+	sprintf(buff, "telnetd: fork() failed: %s\r\n", strerror(errno));
+	(void) write(1, buff, strlen(buff));
+  }
+
+  if (pid != 0) {
+	/* network -> login process */
+	while (!io_done && (i = read(0, buff, sizeof(buff))) > 0) {
+		tel_in(pty_fd, 1, buff, i);
+	}
+	/* EOF, kill opposite number and exit. */
+	(void) kill(pid, SIGKILL);
+  } else {
+  	/* login process -> network */
+	while ((i = read(pty_fd, buff, sizeof(buff))) > 0) {
+		tel_out(1, buff, i);
+	}
+	/* EOF, alert opposite number and exit. */
+	(void) kill(getppid(), SIGALRM);
+  }
+  /* EOF. */
+}
+
+void sig_done(sig)
+int sig;
+{
+  io_done = 1;
+  alarm(1);			/* there is always a chance... */
+}

commands/telnetd/wtmp.c

@@ -0,0 +1,113 @@
+/*
+ * TNET		A server program for MINIX which implements the TCP/IP
+ *		suite of networking protocols.  It is based on the
+ *		TCP/IP code written by Phil Karn et al, as found in
+ *		his NET package for Packet Radio communications.
+ *
+ *		This file contains an implementation of the "server"
+ *		for the TELNET protocol.  This protocol can be used to
+ *		remote-login on other systems, just like a normal TTY
+ *		session.
+ *
+ * Usage:	telnetd [-dv]
+ *
+ * Version:	@(#)telnetd.c	1.00	07/26/92
+ *
+ * Author:	Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ *		Michael Temari, <temari@temari.ae.ge.com>
+ */
+#include <sys/types.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <utmp.h>
+#include <time.h>
+#include <stdio.h>
+#include "telnetd.h"
+
+static char PATH_UTMP[] = "/etc/utmp";
+static char PATH_WTMP[] = "/usr/adm/wtmp";
+
+_PROTOTYPE(void wtmp, (int type, int linenr, char *line, pid_t pid,
+								char *host));
+_PROTOTYPE(void report, (char *label));
+
+void wtmp(type, linenr, line, pid, host)
+int type;			/* type of entry */
+int linenr;			/* line number in ttytab */
+char *line;			/* tty name (only good on login) */
+pid_t pid;			/* pid of process */
+char *host;			/* name of the remote host */
+{
+/* Log an event into the UTMP and WTMP files. */
+
+  struct utmp utmp;		/* UTMP/WTMP User Accounting */
+  int fd;
+
+  /* Clear the utmp record. */
+  memset((void *) &utmp, 0, sizeof(utmp));
+
+  /* Fill in utmp. */
+  switch (type) {
+  case LOGIN_PROCESS:
+  	/* A new login, fill in line and host name. */
+	strncpy(utmp.ut_line, line, sizeof(utmp.ut_line));
+	strncpy(utmp.ut_host, host, sizeof(utmp.ut_host));
+	break;
+
+  case DEAD_PROCESS:
+	/* A logout.  Use the current utmp entry, but make sure it is a
+	 * user process exiting, and not getty or login giving up.
+	 */
+	if ((fd = open(PATH_UTMP, O_RDONLY)) < 0) {
+		if (errno != ENOENT) report(PATH_UTMP);
+		return;
+	}
+	if (lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
+		|| read(fd, &utmp, sizeof(utmp)) == -1
+	) {
+		report(PATH_UTMP);
+		close(fd);
+		return;
+	}
+	close(fd);
+	if (utmp.ut_type != USER_PROCESS) return;
+	strncpy(utmp.ut_name, "", sizeof(utmp.ut_name));
+	break;
+  }
+
+  /* Finish new utmp entry. */
+  utmp.ut_pid = pid;
+  utmp.ut_type = type;
+  utmp.ut_time = time((time_t *) 0);
+
+  /* Write new entry to utmp. */
+  if ((fd = open(PATH_UTMP, O_WRONLY)) < 0
+	|| lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
+	|| write(fd, &utmp, sizeof(utmp)) == -1
+  ) {
+	if (errno != ENOENT) report(PATH_UTMP);
+  }
+  if (fd != -1) close(fd);
+
+  if (type == DEAD_PROCESS) {
+	/* Add new wtmp entry. */
+	if ((fd = open(PATH_WTMP, O_WRONLY | O_APPEND)) < 0
+		  || write(fd, &utmp, sizeof(utmp)) == -1
+	) {
+		if (errno != ENOENT) report(PATH_WTMP);
+	}
+	if (fd != -1) close(fd);
+  }
+}
+
+void report(label)
+char *label;
+{
+  char message[128];
+
+  sprintf(message, "telnetd: %s: %s\r\n", strerror(errno));
+  (void) write(1, message, strlen(message));
+}