rfc1116.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                    Internet Engineering Task Force
Request for Comments: 1116                 Telnet Linemode Working Group
                                                       D. Borman, Editor
                                                     Cray Research, Inc.
                                                             August 1989


                         Telnet Linemode Option

Status of this Memo

   This RFC describes a proposed elective standard for the Internet
   community.  Hosts on the Internet that support Linemode within the
   Telnet protocol are expected to adopt and implement this standard.
   Distribution of this memo is unlimited.

Overview

   Linemode Telnet is a way of doing terminal character processing on
   the client side of a Telnet connection.  While in Linemode with
   editing enabled for the local side, network traffic is reduced to a
   couple of packets per command line, rather than a couple of packets
   per character typed.  This is very useful for long delay networks,
   because the user has local response time while typing the command
   line, and only incurs the network delays after the command is typed.
   It is also useful to reduce costs on networks that charge on a per
   packet basis.

Table of Contents

   1.   Command Names and Codes                                        2
   2.   Command Meanings                                               3
   2.1  The LINEMODE function                                          3
   2.2  LINEMODE suboption MODE                                        3
   2.3  LINEMODE suboption FORWARDMASK                                 4
   2.4  LINEMODE suboption SLC, Set Local Characters                   5
   2.5  New control characters                                         8
   3.   Default Specification                                          9
   4.   Motivation                                                     9
   5.   Implementation Rules                                          11
   5.1  User Interface                                                11
   5.2  End of line terminators                                       12
   5.3  Output processing                                             12
   5.4  A terminal driver in Telnet?                                  12
   5.5  Setting of Local Characters                                   12
   5.6  FORWARDMASK and SLC_FORW1 and SLC_FORW2                       13
   5.7  Valid and invalid modes and values.                           14
   5.8  Flushing input and output                                     14



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   5.9  State diagram for SLC                                         16
   5.10 Example of a connection                                       17
   6.   Other Telnet options and RFCs                                 20

1.  Command Names and Codes

       LINEMODE        34
           MODE             1
               EDIT             1
               TRAPSIG          2
               MODE_ACK         4
           FORWARDMASK      2
           SLC              3
               SLC_SYNCH        1
               SLC_BRK          2
               SLC_IP           3
               SLC_AO           4
               SLC_AYT          5
               SLC_EOR          6
               SLC_ABORT        7
               SLC_EOF          8
               SLC_SUSP         9
               SLC_EC          10
               SLC_EL          11
               SLC_EW          12
               SLC_RP          13
               SLC_LNEXT       14
               SLC_XON         15
               SLC_XOFF        16
               SLC_FORW1       17
               SLC_FORW2       18

               SLC_DEFAULT      3
               SLC_VALUE        2
               SLC_CANTCHANGE   1
               SLC_NOSUPPORT    0
               SLC_LEVELBITS    3

               SLC_ACK        128
               SLC_FLUSHIN     64
               SLC_FLUSHOUT    32
       EOF            236
       SUSP           237
       ABORT          238







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2.  Command Meanings

2.1 The LINEMODE function

   IAC WILL LINEMODE

      The sender of this command REQUESTS permission to begin sub-
      negotiation of the editing/signaling status.  This should only be
      sent by the client side of the connection.

   IAC WONT LINEMODE

      The sender of this command DEMANDS that sub-negotiation of the
      editing/signaling status not be allowed.

   IAC DO LINEMODE

      The sender of this command REQUESTS that the remote side begin
      subnegotiation of the editing/signaling status.  This should only
      be sent by the server side of the connection.

   IAC DONT LINEMODE

      The sender of this command DEMANDS that the remote side not begin
      subnegotiation of the editing/signaling status.

2.2 LINEMODE suboption MODE

   IAC SB LINEMODE MODE mask IAC SE

      The sender of this command CONFIRMS, or REQUESTS permission for, a
      switch to the mode defined by "mask".

   The "mask" is a bit mask of various modes that the connection can be
   in.  Under normal operation, the server side of the connection will
   initiate mode changes, and the client will confirm the mode changes.
   The currently defined modes are:

      EDIT    When set, the client side of the connection should
              process all input lines, performing any editing
              functions, and only send completed lines to the remote
              side.  When unset, client side should not process any
              input from the user, and the server side should take
              care of all character processing that needs to be done.

      TRAPSIG When set, the client side should translate appropriate
              interrupts/signals to their Telnet equivalent.
              (These would be IP, BRK, AYT, ABORT, EOF, and SUSP.)



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RFC 1116                 Telnet Linemode Option              August 1989


              When unset, the client should pass interrupts/signals
              as their normal ASCII values.

      FLOW    Logically, this belongs in the "mask".  However,
              this would overlap the Telnet TOGGLE-FLOW-CONTROL
              option, so the Telnet TOGGLE-FLOW-CONTROL option is
              used instead.  When DO/WILL LINEMODE is negotiated,
              DO/WILL TOGGLE-FLOW-CONTROL should also be negotiated.
              See RFC 1080, "Telnet Remote Flow Control", for
              correct usage.

      ECHO    Logically, this belongs in the "mask".  However,
              this would overlap the Telnet ECHO option, so the
              Telnet ECHO option is used instead.  The client side
              should never negotiate "WILL ECHO".  When the server
              has negotiated "WILL ECHO", the client should not
              echo data typed by the user back to the user.  When
              the server has negotiated "WONT ECHO", the client is
              responsible for echoing data typed by the user back
              to the user.  See RFC 857, "Telnet ECHO OPTION" for
              a complete discussion on the use of the Telnet ECHO
              option.

   When the client side of a connection receives a MODE command, it MUST
   agree with at least the state of the EDIT and TRAPSIG bits.  If a
   MODE command is received with a mode mask that is currently in use
   (ignoring the MODE_ACK bit), the MODE command is ignored.  If a MODE
   command is received that is different from the current mode mask,
   then a reply is sent with either the new mode mask and the MODE_ACK
   bit set, or a subset of the new mode mask.  The only exception is
   that if the server receives a MODE with either the EDIT or TRAPSIG
   bits not set, it may set the EDIT and TRAPSIG bits in the response,
   and if the client receives a MODE with the EDIT or TRAPSIG bits set,
   it may not clear them in the response.

   When a MODE command is received with the MODE_ACK bit set, and the
   mode is different that what the current mode is, the client will
   ignore the new mode, and the server will switch to the new mode.
   This ensures that both sides of the connection will resolve to the
   same mode.  In all cases, a response is never generated to a MODE
   command that has the MODE_ACK bit set.

2.3 LINEMODE suboption FORWARDMASK

   IAC SB LINEMODE DO FORWARDMASK mask0 mask1 ... mask31 IAC SE

      The sender of this command request that the other side send any
      buffered data when any of the ASCII characters defined by the bit



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      mask are received.  Only the side of the connection that sent DO
      LINEMODE (the server side) may negotiate this.  The mask is up to
      32 octets long.  Each octet represents 8 ASCII character codes.
      The high order bit of mask0 corresponds to an ASCII code of 0.
      The low order bit of mask0 corresponds to an ASCII code of 7.  The
      high order bit of mask1 corresponds to an ASCII code of 8.  The
      low order bit of mask1 corresponds to an ASCII code of 15, and so
      on.  The mask list may be terminated before the end of the list,
      in which case all the rest of the mask octets are assumed to be
      reset (equal to zero).  When the server side is in DONT TRANSMIT-
      BINARY mode, then only the first 16 octets of the mask (ASCII
      codes 0 through 127) are used.  If any individual octet of the
      mask is equal to IAC, it must be sent as a double IAC.

   IAC SB LINEMODE DONT FORWARDMASK IAC SE

      The sender of this command requests that the other side stop using
      the forward mask to determine when to send buffered data.

   IAC SB LINEMODE WILL FORWARDMASK IAC SE

      This command is sent in response to a DO FORWARDMASK command.  It
      indicates that the forward mask will be used to determine when to
      send buffered data.

   IAC SB LINEMODE WONT FORWARDMASK IAC SE

      This command is sent in response to a DO FORWARDMASK command.  It
      indicates that the forward mask will not be used to determine when
      to send buffered data.

2.4 LINEMODE suboption SLC, Set Local Characters

   The SLC suboption uses a list of octet triplets.  The first octet
   specifies the function, the second octet specifies modifiers to the
   function, and the third octet specifies the ASCII character for the
   function.

   IAC SB LINEMODE SLC <list of octet triplets> IAC SE

      The sender of this command REQUESTS that the list of octet
      triplets be used to set the local character to be used to send to
      perform the specified function.

      There are four levels that a function may be set to.
      SLC_NOSUPPORT is the lowest, SLC_CANTCHANGE is the next higher
      level, SLC_VALUE is above that, and SLC_DEFAULT is the highest
      level.



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      If the SLC_LEVELBITS in the second octet are equal to SLC_DEFAULT,
      then this particular function should use the system default on the
      other side of the connection.

      If the SLC_LEVELBITS in the second octet are equal to SLC_VALUE,
      then this function is supported, and the current value is
      specified by the third octet.

      If the SLC_LEVELBITS in the second octet are equal to