262 lines
5.5 KiB
Forth
Executable file
262 lines
5.5 KiB
Forth
Executable file
#!/usr/bin/rre
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# Atua: A Gopher Server
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Atua is a gopher server written in Retro.
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This will get run as an inetd service, which keeps things simple as it
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prevents needing to handle socket I/O directly.
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# Features
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Atua is a minimal server targetting the the basic Gopher0 protocol. It
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supports a minimal gophermap format for indexes and transfer of static
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content.
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-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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# Script Prelude
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Atua uses Retro's *rre* interface layer. Designed to run a single
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program then exit, this makes using Retro as a scripting language
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possible.
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# Configuration
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Atua needs to know:
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- the path to the files to serve
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- the name of the index file
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- The maximum length of a selector
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- The maximum file size
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~~~
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'/home/crc/atua s:keep 'PATH const
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'/gophermap s:keep 'DEFAULT-INDEX const
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#1024 'MAX-SELECTOR-LENGTH const
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#1000000 #4 * 'MAX-FILE-SIZE const
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'forthworks.com s:keep 'SERVER const
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'70 s:keep 'PORT const
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~~~
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# I/O Words
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Retro only supports basic output by default. The RRE interface that
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Atua uses adds support for files and stdin, so we use these and
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provide some other helpers.
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*Console Output*
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The Gopher protocol uses tabs and cr/lf for signficant things. To aid
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in this, I define output words for tabs and end of line.
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~~~
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:eol (-) ASCII:CR c:put ASCII:LF c:put ;
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~~~
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*Console Input*
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Input lines end with a cr, lf, or tab. The `eol?` checks for this.
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The `gets` word could easily be made more generic in terms of what
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it checks for. This suffices for a Gopher server though.
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~~~
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:eol? (c-f)
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[ ASCII:CR eq? ] [ ASCII:LF eq? ] [ ASCII:HT eq? ] tri or or ;
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:s:get (a-)
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buffer:set
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[ c:get dup buffer:add eol? not ] while ;
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~~~
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# Gopher Namespace
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Atua uses a `gopher:` namespace to group the server related words.
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~~~
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{{
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~~~
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First up are buffers for the selector string and the file buffer. The
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variables and buffers are kept private.
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~~~
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'Selector d:create
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MAX-SELECTOR-LENGTH n:inc allot
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:buffer here ;
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~~~
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Next up, variables to track information related to the requested
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selector. Atua will construct filenames based on these.
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~~~
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'Requested-File var
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'Requested-Index var
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~~~
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`FID`, the file id, tracks the open file handle that Atua uses
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when reading in a file. The `Size` variable will hold the size of
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the file (in bytes).
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~~~
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'FID var
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'Size var
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'Mode var
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~~~
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I use a `Server-Info` variable to decide whether or not to display
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the index footer. This will become a configurable option in the
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future.
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~~~
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'Server-Info var
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~~~
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~~~
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:with-path (-s)
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PATH &Selector s:chop s:append ;
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:construct-filenames (-)
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with-path s:keep !Requested-File
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with-path '/gophermap s:append s:keep !Requested-Index
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;
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~~~
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A *gophermap* is a file that makes it easier to handle Gopher menus.
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Atua's gophermap support covers:
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- comment lines
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Comment lines are static text without any tabs. They will be
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reformatted according to protocol and sent.
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- selector lines
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Any line with a tab is treated as a selector line and is transferred
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without changing.
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~~~
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'Tab var
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:eol? [ ASCII:LF eq? ] [ ASCII:CR eq? ] bi or ;
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:tab? @Tab ;
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:check-tab
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dup ASCII:HT eq? [ &Tab v:on ] if ;
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:gopher:gets (a-)
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&Tab v:off
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buffer:set
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[ @FID file:read dup buffer:add check-tab eol? not ] while
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buffer:get drop
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;
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~~~
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The internal helpers are now defined, so switch to the part of the
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namespace that'll be left exposed to the world.
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~~~
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---reveal---
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~~~
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An information line s:get a format like:
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i...text...<tab><tab>null.host<tab>port<cr,lf>
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The `gopher:i` displays a string in this format. It's used later for
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the index footer.
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~~~
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:gopher:i (s-)
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'i%s\t\tnull.host\t1 s:format s:put eol ;
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~~~
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~~~
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:gopher:get-selector (-)
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&Selector s:get ;
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:gopher:file-requested? (-f)
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&Selector s:chop s:length n:-zero? ;
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:gopher:valid-file? (-f)
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[ @Requested-File file:R file:open
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file:size n:strictly-positive? ]
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[ FALSE ] choose ;
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:gopher:get-index (-s)
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@Requested-Index file:exists?
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[ @Requested-Index &Server-Info v:on ]
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[ PATH '/empty.index s:append ] choose ;
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:gopher:file-for-request (-s)
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&Mode v:off
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construct-filenames
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gopher:file-requested?
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[ @Requested-File file:exists? gopher:valid-file?
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[ @Requested-File ]
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[ gopher:get-index ] choose
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]
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[ PATH DEFAULT-INDEX s:append &Server-Info v:on ] choose
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;
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:gopher:read-file (f-s)
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file:R file:open !FID
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buffer buffer:set
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@FID file:size !Size
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@Size [ @FID file:read buffer:add ] times
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@FID file:close
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buffer
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;
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:gopher:line (s-)
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dup [ ASCII:HT eq? ] s:filter s:length #1 gt?
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[ s:put ]
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[ s:put tab SERVER s:put tab PORT s:put ] choose
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eol ;
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:gopher:generate-index (f-)
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file:R file:open !FID
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@FID file:size !Size
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[ buffer gopher:gets
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buffer tab? [ gopher:line ] [ gopher:i ] choose
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@FID file:tell @Size lt? ] while
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@FID file:close
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;
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~~~
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In a prior version of this I used `s:put` to send the content. That
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stopped at the first zero value, which kept it from working with
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binary data. I added `gopher:send` to send the `Size` number of
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bytes to stdout, fixing this issue.
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~~~
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:gopher:send (p-)
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@Size [ fetch-next c:put ] times drop ;
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~~~
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The only thing left is the top level server.
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~~~
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:gopher:server
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gopher:get-selector
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gopher:file-for-request
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@Server-Info
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[ gopher:generate-index
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'------------------------------------------- gopher:i
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'forthworks.com:70_/_atua_/_running_on_retro gopher:i
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'. s:put eol ]
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[ gopher:read-file gopher:send ] choose
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;
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~~~
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Close off the helper portion of the namespace.
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~~~
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}}
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~~~
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And run the `gopher:server`.
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~~~
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gopher:server
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reset
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~~~
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