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little-bell.r

REBOL [ Title: "Little-bell" Date: 8-Jul-1999 Version: 1.0.0 File: %little-bell.r Author: "Ole Friis" Purpose: "Rudimentary Telnet client written in REBOL." Comment: { This script can be used to perform basic Telnet operation over the Internet. It does not support all of RFC 854 (it lacks support for the commands SE, DM, BRK, IP, AO, EL, and SB), but still this should suffice for your basic needs. Perhaps in the future I'll add support for the rest of the RFC 854 commands along with a host of options scattered around in other RFCs. Thanks to: * James Card <%jdcard--inreach--com> for pointing me at the Telnet RFC. * Andrew Martin <%AI--Bri--xtra--co--nz> for the name "Bell". * All the nice and helpful people at REBOL Inc. and on the REBOL mailing list!!! } Email: %ole_f--post3--tele--dk library: [ level: 'advanced platform: none type: 'tool domain: [tcp other-net] tested-under: none support: none license: none see-also: none ] ] ; The supported commands and their meaning, see RFC 854 cmd_AYT: to-char 246 ; Are You There? cmd_EC: to-char 247 ; Erase character cmd_WILL: to-char 251 ; Will cmd_WONT: to-char 252 ; Won't cmd_DO: to-char 253 ; Do cmd_DONT: to-char 254 ; Don't cmd_IAC: to-char 255 ; Interpret as command ; What to do with the various commands command-actions: reduce [ cmd_AYT [ ; Give a sign of life telnet-send "Yes, we're here!" finish-command ] cmd_EC [ ; Erase one character prin "^(back) ^(back)" finish-command ] cmd_WILL [ if 2 = length? command-buffer [ ; Try to stop all of these! telnet-send [cmd_IAC cmd_DONT second command-buffer] finish-command ] ] cmd_WONT [ if 2 = length? command-buffer [ ; We don't care what the other part won't finish-command ] ] cmd_DO [ if 2 = length? command-buffer [ ; No, we won't! telnet-send [cmd_IAC cmd_WONT second command-buffer] finish-command ] ] cmd_DONT [ if 2 = length? command-buffer [ ; No problem, as we won't finish-command ] ] ] ; Cleans up after a finished command finish-command: func [] [ clear command-buffer reading_command: no ] ; Sends a block of characters to the Telnet server telnet-send: func [block] [ append server-port to-string reduce block ] ; Start the session! if error? try [ server-port: open/binary/direct to-url rejoin [ "TCP://" ask "Server name: " ":23" ] ] [print "Could not connect to server" halt] console-port: open/binary [scheme: 'console] ports: reduce [server-port console-port] command-buffer: make string! 20 server-buffer: make string! 2000 console-buffer: make string! 200 reading_command: no while [true] [ port: wait ports ; Should we read from the keyboard or the server? either port = server-port [ ; Get a chunk of input from the server server-buffer: head server-buffer clear server-buffer read-io server-port server-buffer 2000 ; First see if the connection has been closed if 0 = length? server-buffer [ print "** Session finished **" close server-port close console-port halt ] ; Then process the input we just got while [0 < length? server-buffer] [ either reading_command [ insert tail command-buffer first server-buffer server-buffer: next server-buffer switch/default first command-buffer command-actions [ finish-command ] ] [ either next-server-buffer: find server-buffer cmd_IAC [ prin copy/part server-buffer next-server-buffer server-buffer: next next-server-buffer reading_command: yes ] [ prin server-buffer server-buffer: tail server-buffer ] ] ] ] [ ; Process some console input ch: to-char pick port 1 either (ch = newline) or (ch = #"^M") [ telnet-send [console-buffer #"^M" newline] clear console-buffer print "" ] [ either ch = #"^(back)" [ if 0 < length? console-buffer [ prin "^(back) ^(back)" remove back tail console-buffer ] ] [ prin ch append console-buffer ch ] ] ] ]
halt ;; to terminate script if DO'ne from webpage
Notes
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  • (ole_f:post3:tele:dk)
  • (AI:Bri:xtra:co:nz)
  • (jdcard:inreach:com)