readme.txt

经典的unix下telnet的c代码

	$OpenBSD: README,v 1.4 2003/11/08 19:17:29 jmc Exp $

This is a distribution of both client and server telnet.  These programs
have been compiled on:
			telnet	telnetd
	4.4 BSD-Lite	  x	  x
	4.3 BSD Reno	  X	  X
	UNICOS 9.1	  X	  X
	UNICOS 9.0	  X	  X
	UNICOS 8.0	  X	  X
	BSDI 2.0	  X	  X
	Solaris 2.4       x       x (no linemode in server)
	SunOs 4.1.4	  X	  X (no linemode in server)
	Ultrix 4.3	  X	  X (no linemode in server)
	Ultrix 4.1	  X	  X (no linemode in server)

In addition, previous versions have been compiled on the following
machines, but were not available for testing this version.
			telnet	telnetd
	Next1.0		  X	  X
	UNICOS 8.3	  X	  X
	UNICOS 7.C	  X	  X
	UNICOS 7.0	  X	  X
	SunOs 4.0.3c	  X	  X (no linemode in server)
	4.3 BSD		  X  	  X (no linemode in server)
	DYNIX V3.0.12	  X	  X (no linemode in server)
	Ultrix 3.1	  X	  X (no linemode in server)
	Ultrix 4.0	  X	  X (no linemode in server)
	SunOs 3.5	  X	  X (no linemode in server)
	SunOs 4.1.3	  X	  X (no linemode in server)
	Solaris 2.2       x       x (no linemode in server)
	Solaris 2.3       x       x (no linemode in server)
	BSDI 1.0	  X	  X
	BSDI 1.1	  X	  X
	DYNIX V3.0.17.9	  X	  X (no linemode in server)
	HP-UX 8.0	  x       x (no linemode in server)

This code should work, but there are no guarantees.

Oct 23, 1995

This is a bugfix release.

	The change in the previous release from using makeutx() to
	pututxline() caused problems on SunOS/Solaris.  It has been
	changed back to using makeutx().  Symptoms include users
	getting error messages when logging in about not being able
	to open the tty.

	Using memmove() instead of memcpy() caused problems under
	SunOS 4.x, since it doesn't have memmove().  Config.generic
	has been modified to include mem.o for SunOS 4.x.

	Some new code was added to telnetd to do some enviornment
	variable cleanup before execing login.  Thanks to Sam Hartman
	at MIT for pointing this out.

	A couple of other minor bugfixes.

May 30, 1995

This release represents what is on the 4.4BSD-Lite2 release, which
should be the final BSD release.  I will continue to support of
telnet, The code (without encryption) is available via anonymous ftp
from ftp.cray.com, in src/telnet/telnet.YY.MM.DD.NE.tar.Z, where
YY.MM.DD is replaced with the year, month and day of the release.
If you can't find it at one of these places, at some point in the
near future information about the latest releases should be available
from ftp.borman.com.

In addition, the version with the encryption code is available via
ftp from net-dist.mit.edu, in the directory /pub/telnet.  There
is a README file there that gives further information on how
to get the distribution.

Questions, comments, bug reports and bug fixes can be sent to
one of these addresses:
		[e-mail]
		[e-mail]
		[e-mail]

This release is mainly bug fixes and code cleanup.

	Replace all calls to bcopy()/bzero() with calls to
	memmove()/memset() and all calls to index()/rindex()
	with calls to strchr()/strrchr().

	Add some missing diagnostics for option tracing
	to telnetd.

	Add support for BSDI 2.0 and Solaris 2.4.

	Add support for UNICOS 8.0

	Get rid of expanded tabs and trailing white spaces.

	From Paul Vixie:
		Fix for telnet going into an endless spin
		when the session dies abnormally.

	From Jef Poskanzer:
		Changes to allow telnet to compile
		under SunOS 3.5.

	From Philip Guenther:
		makeutx() doesn't expand utmpx,
		use pututxline() instead.

	From Chris Torek:
		Add a sleep(1) before execing login
		to avoid race condition that can eat
		up the login prompt.
		Use terminal speed directly if it is
		not an encoded value.

	From Steve Parker:
		Fix to realloc() call.  Fix for execing
		login on solaris with no user name.

January 19, 1994

This is a list of some of the changes since the last tar release
of telnet/telnetd.  There are probably other changes that aren't
listed here, but this should hit a lot of the main ones.

   General:
	Changed #define for AUTHENTICATE to AUTHENTICATION
	Changed #define for ENCRYPT to ENCRYPTION
	Changed #define for DES_ENCRYPT to DES_ENCRYPTION

	Added support for SPX authentication: -DSPX

	Added support for Kerberos Version 5 authentication: -DKRB5

	Added support for ANSI C function prototypes

	Added support for the NEW-ENVIRON option (RFC-1572)
	including support for USERVAR.

	Made support for the old Environment Option (RFC-1408)
	conditional on -DOLD_ENVIRON

	Added #define ENV_HACK - support for RFC 1571

	The encryption code is removed from the public distributions.
	Domestic 4.4 BSD distributions contain the encryption code.

	ENV_HACK: Code to deal with systems that only implement
		the old ENVIRON option, and have reversed definitions
		of ENV_VAR and ENV_VAL.  Also fixes ENV processing in
		client to handle things besides just the default set...

	NO_BSD_SETJMP: UNICOS configuration for
		UNICOS 6.1/6.0/5.1/5.0 systems.

	STREAMSPTY: Use /dev/ptmx to get a clean pty.  This
		is for SVr4 derivatives (Like Solaris)

	UTMPX: For systems that have /etc/utmpx. This is for
		SVr4 derivatives (Like Solaris)

	Definitions for BSDI 1.0

	Definitions for 4.3 Reno and 4.4 BSD.

	Definitions for UNICOS 8.0 and UNICOS 7.C

	Definitions for Solaris 2.0

	Definitions for HP-UX 8.0

	Latest Copyright notices from Berkeley.

	FLOW-CONTROL: support for RFC-XXXx


   Client Specific:

	Fix the "send" command to not send garbage...

	Fix status message for "skiprc"

	Make sure to send NAWS after telnet has been suspended
	or an external command has been run, if the window size
	has changed.

	sysV88 support.

   Server Specific:

	Support flowcontrol option in non-linemode servers.

	-k Server supports Kludge Linemode, but will default to
	   either single character mode or real Linemode support.
	   The user will have to explicitly ask to switch into
	   kludge linemode. ("stty extproc", or escape back to
	   to telnet and say "mode line".)

	-u Specify the length of the hostname field in the utmp
	   file.  Hostname longer than this length will be put
	   into the utmp file in dotted decimal notation, rather
	   than putting in a truncated hostname.
	
	-U Registered hosts only.  If a reverse hostname lookup
	   fails, the connection will be refused.

	-f/-F
	   Allows forwarding of credentials for KRB5.

Februrary 22, 1991:

    Features:

	This version of telnet/telnetd has support for both
	the AUTHENTICATION and ENCRYPTION options.  The
	AUTHENTICATION option is fairly well defined, and
	an option number has been assigned to it.  The
	ENCRYPTION option is still in a state of flux; an
	option number has been assigned to, but it is still
	subject to change.  The code is provided in this release
	for experimental and testing purposes.

	The telnet "send" command can now be used to send
	do/dont/will/wont commands, with any telnet option
	name.  The rules for when do/dont/will/wont are sent
	are still followed, so just because the user requests
	that one of these be sent doesn't mean that it will
	be sent...

	The telnet "getstatus" command no longer requires
	that option printing be enabled to see the response
	to the "DO STATUS" command.

	A -n flag has been added to telnetd to disable
	keepalives.

	A new telnet command, "auth" has been added (if
	AUTHENTICATE is defined).  It has four sub-commands,
	"status", "disable", "enable" and "help".

	A new telnet command, "encrypt" has been added (if
	ENCRYPT is defined).  It has many sub-commands:
	"enable", "type", "start", "stop", "input",
	"-input", "output", "-output", "status", and "help".

	The LOGOUT option is now supported by both telnet
	and telnetd, a new command, "logout", was added
	to support this.

	Several new toggle options were added:
	    "autoencrypt", "autodecrypt", "autologin", "authdebug",
	    "encdebug", "skiprc", "verbose_encrypt"

	An "rlogin" interface has been added.  If the program
	is named "rlogin", or the "-r" flag is given, then
	an rlogin type of interface will be used.
		~.	Terminates the session
		~<susp> Suspend the session
		~^]	Escape to telnet command mode
		~~	Pass through the ~.
	    BUG: If you type the rlogin escape character
		 in the middle of a line while in rlogin
		 mode, you cannot erase it or any characters
		 before it.  Hopefully this can be fixed
		 in a future release...

    General changes:

	A "libtelnet.a" has now been created.  This libraray
	contains code that is common to both telnet and
	telnetd.  This is also where library routines that
	are needed, but are not in the standard C library,
	are placed.

	The makefiles have been re-done.  All of the site
	specific configuration information has now been put
	into a single "Config.generic" file, in the top level
	directory.  Changing this one file will take care of
	all three subdirectories.  Also, to add a new/local
	definition, a "Config.local" file may be created
	at the top level; if that file exists, the subdirectories
	will use that file instead of "Config.generic".

	Many 1-2 line functions in commands.c have been
	removed, and just inserted in-line, or replaced
	with a macro.

    Bug Fixes:

	The non-termio code in both telnet and telnetd was
	setting/clearing CTLECH in the sg_flags word.  This
	was incorrect, and has been changed to set/clear the
	LCTLECH bit in the local mode word.

	The SRCRT #define has been removed.  If IP_OPTIONS
	and IPPROTO_IP are defined on the system, then the
	source route code is automatically enabled.

	The NO_GETTYTAB #define has been removed; there
	is a compatibility routine that can be built into
	libtelnet to achive the same results.

	The server, telnetd, has been switched to use getopt()
	for parsing the argument list.

	The code for getting the input/output speeds via
	cfgetispeed()/cfgetospeed() was still not quite
	right in telnet.  Posix says if the ispeed is 0,
	then it is really equal to the ospeed.

	The suboption processing code in telnet now has
	explicit checks to make sure that we received
	the entire suboption (telnetd was already doing this).

	The telnet code for processing the terminal type
	could cause a core dump if an existing connection
	was closed, and a new connection opened without
	exiting telnet.

	Telnetd was doing a TCSADRAIN when setting the new
	terminal settings;  This is not good, because it means
	that the tcsetattr() will hang waiting for output to
	drain, and telnetd is the only one that will drain
	the output...  The fix is to use TCSANOW which does
	not wait.

	Telnetd was improperly setting/clearing the ISTRIP
	flag in the c_lflag field, it should be using the
	c_iflag field. 

	When the child process of telnetd was opening the
	slave side of the pty, it was re-setting the EXTPROC
	bit too early, and some of the other initialization
	code was wiping it out.  This would cause telnetd
	to go out of linemode and into single character mode.

	One instance of leaving linemode in telnetd forgot
	to send a WILL ECHO to the client, the net result
	would be that the user would see double character
	echo.

	If the MODE was being changed several times very
	quickly, telnetd could get out of sync with the
	state changes and the returning acks; and wind up
	being left in the wrong state.

September 14, 1990:

	Switch the client to use getopt() for parsing the
	argument list.  The 4.3Reno getopt.c is included for
	systems that don't have getopt().

	Use the posix _POSIX_VDISABLE value for what value
	to use when disabling special characters.  If this
	is undefined, it defaults to 0x3ff.

	For non-termio systems, TIOCSETP was being used to
	change the state of the terminal.  This causes the
	input queue to be flushed, which we don't want.  This
	is now changed to TIOCSETN.

	Take out the "#ifdef notdef" around the code in the
	server that generates a "sync" when the pty oputput
	is flushed.  The potential problem is that some older
	telnet clients may go into an infinate loop when they
	receive a "sync", if so, the server can be compiled
	with "NO_URGENT" defined.

	Fix the client where it was setting/clearing the OPOST
	bit in the c_lflag field, not the c_oflag field.

	Fix the client where it was setting/clearing the ISTRIP
	bit in the c_lflag field, not the c_iflag field.  (On
	4.3Reno, this is the ECHOPRT bit in the c_lflag field.)
	The client also had its interpretation of WILL BINARY
	and DO BINARY reversed.

	Fix a bug in client that would cause a core dump when
	attempting to remove the last environment variable.

	In the client, there were a few places were switch()
	was being passed a character, and if it was a negative
	value, it could get sign extended, and not match