From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc560.txt | 675 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 675 insertions(+) create mode 100644 doc/rfc/rfc560.txt (limited to 'doc/rfc/rfc560.txt') diff --git a/doc/rfc/rfc560.txt b/doc/rfc/rfc560.txt new file mode 100644 index 0000000..6cf9f17 --- /dev/null +++ b/doc/rfc/rfc560.txt @@ -0,0 +1,675 @@ + + + + + + +Network Working Group D. Crocker +Request for Comments: 560 J. Postel +Category: Protocols, TELNET 20 August 1973 +NIC: 18492 + + + Remote Controlled Transmission & Echoing TELNET Option + + Currently, a terminal in character-at-a-time transmission and + foreign-host echo causes four Network Messages for each character + struck. (The character sent from local to foreign host; its RFNM; + the echoed character sent from the foreign to the local host; and its + RFNM.) + + By eliminating most echoing (1/2 as many messages) and packaging the + characters into useful units (assuming an average of five character + per unit; therefore another 80 per cent reduction), it is believed + that almost a 90 per cent reduction in character-mode interactive + Network terminal traffic can be attained. + + The packaging of characters and elimination of foreign echoing should + also lessen the load placed on the foreign hosts. + +1. Command name and code: + + RCTE + +2. Command meanings: + + IAC WILL RCTE + + The sender of this command REQUESTS or AGREES to use the RCTE + option, and will send instructions for controlling the other + side's terminal printer. + + IAC WON'T RCTE + + The sender of this option REFUSES to send instructions for + controlling the other side's terminal printer. + + IAC DO RCTE + + The sender REQUEST or AGREES to have the other side (sender of + WILL RCTE) issue commands which will control his (sender of the + DO) output to the terminal printer. + + + + + + +Crocker, et. al. [Page 1] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + IAC DON'T RCTE + + The sender of this command REFUSES to allow the other side to + control his (sender of DON'T) terminal printer. + + IAC SB RCTE [BC1 BC2] [TC1 TC2] + + where: + + is one 8-bit byte having the following flags (bits are + counted from the right): + + Bit Meaning + + 0 0 = Ignore all other bits in this byte and repeat the + last that was sent. Equals a 'continue what + you have been doing'. + 1 = Perform actions as indicated by other bits in this + byte. + + 1 0 = Print (echo) Break character + 1 = Skip (don't echo) Break character + + 2 0 = Print (echo) text up to Break character + 1 = Skip (don't echo) text up to Break character + + 3 0 = Continue using same classes of Break characters. + 1 = The two 8-bit bytes following this byte contain + flags for the new Break classes. + + 4 0 = Continue using same classes of Transmit characters. + 1 = Reset Transmit classes according to the two bytes + following 1) the Break classes bytes, if the Break + classes are also being reset, or 2) this byte, if + the Break classes are NOT also being reset. + + Value (decimal) of the byte and its meaning: + + 0 = Continue what you have been doing + + 1 = Print (echo) up to AND INCLUDING Break character + + 3 = Print up to Break character and SKIP (don't echo) + Break character + + 5 = Skip text (don't echo) up to Break character, but + PRINT Break character + + + + +Crocker, et. al. [Page 2] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + 7 = Skip up to and including Break character + + Add one of the previous non-zero values to one of the + following values, to get the total decimal value for + the byte (Note that Classes may not be reset without + also resetting the printing action; so an odd number + is guaranteed): + + 8 = Set Break classes (using the next two bytes [BC1 + BC2]) + + 16 = Set Transmission classes (using the next two bytes + [TC1 TC2]) + + 24 = Set Break classes (using the next two bytes [BC1 + BC2]) and the Transmission classes (using the two + bytes after that [TC1 TC2]). + + Sub-commands (IAC SB RCTE...) are only sent by the Controlling + Host and, in addition to other functions, functionally replace the + Go-Ahead (IAC GA) Telnet Command. + +3. Default: + + WON'T RCTE -- DON'T RCTE + + Neither host asserts special control over the other host's + terminal printer. + +4. Motivation for the option: + + RFC's 1, 5 and 51 discuss Network and process efficiency and + smoothness. + + RFC 357, by John Davidson, introduces the problem of echoing delay + that occurs when a remote user accesses a full-duplex host, thru a + satellite link. In order to save the many thousands of miles of + transit time for each echoed character, while still permitting full + server responsiveness and clean terminal output, an echo control + similar to that used by some Time-sharing systems is suggested for + the entire Network. + + In effect, the proposed option involves making a user host + carefully regulate the local terminal printer according to + explicit instructions from the foreign (serving) host. + + + + + + +Crocker, et. al. [Page 3] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + An important additional issue is efficient Network transmission. + Implementation of the Davidson Echoing Scheme will eliminate almost + all server-to-user echoing. + + The proposed option also requests using hosts to buffer a + terminal's input to the foreign host until it forms a useful unit + (with "useful unit" delimited by Break or Transmission characters + as described below). Therefore, fewer messages are sent on the + user-to-server path. + + N.B.: This option is only intended for use with full-duplex hosts. + The Go-Ahead Telnet feature is completely adequate for HALF-duplex + server hosts. + +5. Explicit description of control mechanism: + + A. Overview of Interaction + + (1) Agree to use RCTE option + (2) User holds echo printing until instructed by server to do + otherwise + (3) Server may send output to terminal printer. + (4) Network output is printed up to an RCTE command + (5) Server sends IAC SB RCTE + (6) User acts upon the command up to a Break character or until + receipt of output from the server host. + (7) Go to (2) + + Note: Output from the server host may occur at any time, in which + case, the flow of control switches to (2) and then proceeds to + (3), (4), etc. + + B. Explanation: + + (1) Both Hosts agree to use the RCTE option. After that, the + using host (IAC DO RCTE) merely acts upon the Controlling + (serving) host's commands and does not issue any RCTE commands + unless and until it (using host) decides to stop allowing use + of the option (by sending IAC DON'T RCTE). + + (2) User host begins synchronization between the serving host and + itself by suspending terminal echo printing until directed to + do otherwise by the controlling host, thru an IAC SB RCTE + . + + + + + + + +Crocker, et. al. [Page 4] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + (3) The server may send output to the terminal printer, either in + response to input from the user (in which case it is already + synchronized with the terminal input) or spontaneously. In + the latter case, flow of control automatically switches to (2) + and continues from there. Output from the server is defined + as completed when step (5) occurs. That is, text from the + Server to the terminal printer MUST end with an RCTE command. + + (4) Any output from the server is printed on the terminal + IMMEDIATELY. Again note that the end of such output is + defined to be the occurrence of an IAC SB RCTE command. + + (5) Server sends an RCTE command. The command may redefine Break + and Transmission classes, Action to be performed on Break + characters, and action to be performed on text. Each of these + independent functions is controlled by separate bits in the + byte. + + a. A Transmission character is one which REQUIRES the User + Host to transmit all text accumulated up to and including + its occurrence. (For Net efficiency, User hosts are + DISCOURAGED from sending before the occurrence of a + Transmission character). + + If the Transmission Classes bit (Bit 4) is on, the two + bytes following the two Break Classes bytes (or + immediately following the byte, if the Break + Classes bit is not on) will indicate what classes are to + be enabled. + + If the Bit is OFF, the Transmission classes remain + unchanged. When the RCTE option is first initiated, NO + CLASSES are in effect. That is, no character will be + considered a Transmission character. (As if both TC1 + and TC2 are zero.) + + b. A Break character has the effect of a Transmission + character, but also causes the User host to stop its + print/discard action upon the User's input text, until + directed to do otherwise by another IAC SB RCTE + command from the Serving host. Break characters therefore + define printing units. "Break character" as used in this + document does NOT mean Telnet Break character. + + If the Break Classes bit (Bit 3) is on, the two bytes + following will indicate what classes are to be + enabled. There are currently nine (9) classes defined, + with room for expansion. + + + +Crocker, et. al. [Page 5] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + If the bit is OFF, the Break classes remain unchanged. + When the RCTE option is initiated, CLASSES 4, 5, and 9 + are to be in effect. That is, Format Effectors, Non- + format effector Control Characters and DEL, and + Punctuation characters are to be Break characters. + + c. The list of the character classes, used to define Break and + Transmission classes are listed at the end of this + document, in the "Tables" Section. + + d. Because Break characters are special, the print/discard + action that should be performed upon them is not always the + same as should be performed upon the rest of the input + text. + + For example, while typing a filename to TENEX, I want the + text of the filename to be printed (echoed); but I do + not want the (if I use the name completion + feature) to be printed. + + If Bit 1 is ON The Break character is NOT to be printed. + + e. A separate bit (Bit 2) signals whether or not the text + itself should be printed (echoed) to the terminal. If Bit + 2 = 0, then the text IS to be printed. + + f. Yet another bit (Bit 0 - right-most bit) signals whether or + not any of the other bits of the command should be checked. + If this bit is OFF, then the command should be interpreted + to mean "continue whatever echoing strategy you have been + following, using the same Break and Transmission classes." + + This is particularly useful for the command that + follows spontaneously generated output from the Serving + host (such as "System Going Down") which needs to signal + End-of-Message, but does not usually want to reset any + other conditions. + + The server may, however, alter user action after a + spontaneous message, but it is possible that text will + be lost, or printed when it should not be, since there + is no guarantee that the RCTE from the serving + host will be properly synchronized with the terminal + input. + + + + + + + +Crocker, et. al. [Page 6] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + (6) Input from the terminal is (hopefully) buffered up to the + occurrence of a Transmission or Break character; and the input + text is echoed or not echoed, up to the occurrence of a Break + Character. The most recent RCTE command determines the echo, + Transmission and Break actions. + + (7) When a Break character is typed, the cycle of control is + complete and action re-commences at (2). Action also + automatically switches to (2) upon receipt of any text from + the Server host. + + C. Notes, Comments, Etc.: + + (1) Even-Numbered Commands, greater than zero, are in error, since + they will have the low-order bit off. The command should be + interpreted as equal to zero, which means that any Classes + Reset bytes ([TC1 TC2] [BC1 BC2]) will be in error. + + (2) Servers will generally instruct Users NOT to echo Break + Characters, even though it might be alright to echo most Break + characters. For example, is usually a safe character to + echo but is not. TENEX Exec is willing to accept + either, during filename specification. Therefore, the user + must be instructed NOT to echo ANY Break Characters. + + This is generally a tolerable problem, since the server has to + send an RCTE command at this point, anyhow. Adding the Break + character to the message (so that it appears to be echoed) + will not cause any extra Network traffic. + + (3) The RCTE Option entails a rather large overhead. In a true + character-at-a-time situation, this overhead is not justified. + But on the average, it should result in significant savings, + both in Network traffic and Host wake-ups. + + (4) A severe (User) site-dependent problem will be buffering + type-ahead input from the terminal. It is possible, + especially in the case of TIPS, that the input buffer will + overflow often. If the receiving (serving) host will permit, + the accumulated text should be transmitted at this point. If + the text cannot be transmitted and further typing by the user + will result in lost text, the user should be notified. + + + + + + + + + +Crocker, et. al. [Page 7] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + D. Sample Interaction: + + "S:" is sent from serving (WILL RCTE) host to Using host. + "U:" is sent from Using (DO RCTE) host to Serving host. + "T:" is entered by the terminal user. + "P:" is printed on the terminal. + + Text surrounded by square brackets ([]) is commentary. + Text surrounded by angle brackets (<>) is to be taken as a single + unit. E.G., carriage return is , and the decimal value 27 + is represented <27>. + + The following interaction shows a Logon to a Tenex, initiation of + the DED editor, insertion of some text and return to the Exec + level. A Telnet connection has already been opened, but the TENEX + prompt has not yet been issued. The hosts first discuss using the + RCTE option: + + S: + + U: + + S: TENEX 1.31.18, TENEX EXEC 1.50.2 @ + <11><1><24> + + [Print the Herald and echo input text upto a Break character, + but do not echo the Break Character. Classes 4 (Format + Effectors), 5 (Non-format effector Controls and ), and 9 + () act as Break Characters.] + + P: TENEX 1.31.18, TENEX EXEC 1.50.2 @ + + T: LOGIN ARPA + + P: LOGIN + + U: LOGIN + + S: <0> + + P: ARPA + + U: ARPA + + S: (PASSWORD) : <7> + + P: (PASSWORD) : + + + + +Crocker, et. al. [Page 8] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + T: WASHINGTON 1000 + + [The password "WASHINGTON" is not echoed. Action on "1000" + is withheld] + + U: WASHINGTON + + S: <3> + + P: 1000 + + U: 1000 + + S: JOB 17 ON TTY41 7-JUN-73 14:13 @ + <0> + + P: JOB 17 ON TTY41 7-JUN-73 14:13 @ + + T: DED + + P: DED + + U: DED + + S: .SAV;1 <0> + + P: .SAV;1 + + U: + + S: Ded 3/14/73 DRO,KRK : + <15><1><255> + + [The program is started and the DED prompt ":" is sent. At the + command level, DED responds to every character.] + + P: DED 3/14/73 DRP,KRK : + + T: IThis is a text line. This is another test line.<^Z> Q + + ["I" means Insert Text. The text follows, terminated by a + Control-Z. The "Q" instructs DED to Quit.] + + U: I + + + + + + + +Crocker, et. al. [Page 9] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + S: I* <11><0><24> + + [DED prompts the user, during text input, with an asterisk at + the beginning of every line.] + + P: I *This is a test line. + + U: This is a test line. + + S: * + + P: * This is another test line. + + U: This is another test line.<^Z> + + S: ^Zlf>: <15><1><255> + + [The returned "^Z" is two characters, not the ASCII Control-Z.] + + U: Q + + [Note that the "Q" is not yet printed on the terminal, since it + is a Break character.] + + S: Q@ <11><1><24> + + P: Q @ + + And the user is returned to the Exec level. + + E. Tables: + + (1) is one 8-bit byte having the following flags (bits are + counted from the right): + + Bit Meaning + + 0 0 = Ignore all other bits in this byte and repeat the last + that was sent. Equals a 'continue what you have + been doing'. + + 1 = Perform actions as indicated by other bits in this + byte. + + 1 0 = Print (echo) Break character + 1 = Skip (don't echo) Break character + + + + + +Crocker, et. al. [Page 10] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + 2 0 = Print (echo) text up to Break character + 1 = Skip (don't echo) text up to Break character + + 3 0 = Continue using same classes of Break characters. + 1 = The two 8-bit bytes following this byte contain flags + for the new Break classes. + + 4 0 = Continue using same classes of Transmit characters + + 1 = Reset Transmit classes according two the two bytes + following 1) the Break classes bytes, if the Break + classes are also being reset, or 2) this byte, if the + Break classes are NOT also being reset. + + Byte Value (decimal) and its meaning: + + 0 = Continue what you have been doing + + Even numbers greater than zero (i.e., numbers with the right- + most bit off) are in error and should be interpreted as + equal to zero. When the is an even number greater + than zero, Classes bytes TC1 & TC2 and/or BC1 & BC2 must + not be sent. + + 1 = Print (echo) up to AND INCLUDING Break character + + 3 = Print up to Break character and SKIP (don't echo) Break + character + + 5 = Skip text (don't echo) up to Break character, but PRINT + Break character + + 7 = Skip up to and including Break character + + Add one of the previous non-zero values to one of the following + values, to get the total decimal value for the byte (Note + that Classes may not be reset, without also resetting the + printing action; so an odd number is guaranteed): + + 8 = Set Break classes (using the next two bytes [BC1 BC2]) + + 16 = Set Transmission classes (using the next two bytes [TC1 + TC2]) + + 24 = Set Break classes (using the next two bytes [BC1 BC2]) and + the Transmission classes (using the two bytes after that + [TC1 TC2]). + + + + +Crocker, et. al. [Page 11] + +RFC 560 RCT & Echoing TELNET Option August 1973 + + + (2) Classes for Break and Transmission (The right-most bit of the + second byte (TC2 or BC2) represents Class 1; the left-most bit + of the first byte (TC1 or BC1) represents the currently + undefined Class 16): + + 1: Upper-Case Letter (A-Z) + + 2: Lower-case letters (a-z) + + 3: Numbers (0-9) + + 4: Format Effectors ( ) + + 5: Non-format effectors Control Characters, and + + 6: . , ; : ? ! + + 7; - [ ( < > ) ] | + + 8: ' " / \ % @ $ # + - * = ^ <- _ (square box symbol) + + 9: + + And Telnet commands (IAC...) are ALWAYS to have the effect of + a Break character. + + + [ This RFC was put into machine readable form for entry ] + [ into the online RFC archives by Via Genie ] + + + + + + + + + + + + + + + + + + + + + + +Crocker, et. al. [Page 12] + -- cgit v1.2.3