retroforth/example/Casket-HTTP.retro

#!/usr/bin/env retro

## Casket v5

This is a small HTTP/1.1 server written in Retro Forth.

First, some configuration options. Since this will run under
inetd there's no need to specify the port. But the path to the
files to serve is rather useful, so define it here.

~~~
'/home/crc/www 'WEBROOT s:const
~~~

Next, I need to handle the incoming requests. In v0 these were
just discarded, but here we actually want to store the request

So an incoming request will look like:

    GET / HTTP/1.1
    Host: retroforth.org

With the lines ending in a CR,LF sequence.

I need to allocate space for the data I care about. There are
three items:

- The `Requested` file
- The desired virtual `Host`
- The query string (if any)

~~~
'Requested d:create #8193 allot
'Host      d:create #1025 allot
'GET-Query var
~~~

The header processor will read each item and store the `Host`
and `Requested` file. Everything else is ignored.

I implement `eot?` to decide if a line (or field) indicator
has been reached. This is used by `s:get` to decide when the
input should stop. `s:get` records the characters read into
the specified buffer. And finally, `read-request` reads the
input.

~~~
'Done var

:eot? (c-f)
  [ ASCII:CR eq? ]
  [ ASCII:LF eq? ]
  [ ASCII:SPACE eq? ] tri or or ;

:s:get (a-)
  buffer:set [ c:get [ buffer:add ] [ eot? ] bi ] until 
  buffer:get drop ;

:read-request (-)
  [ here s:get
    here s:to-upper 'GET   s:eq? [ &Requested s:get &Done v:inc ] if
    here s:to-upper 'HOST: s:eq? [ &Host      s:get &Done v:inc ] if
    @Done #2 eq? ] until ;
~~~

Next is reading in the desired file. An initial request may be
just a **/**. In this case, Casket will replace the `Requested`
filename with **/index.html**. In the odd case that a file is
requested without a leading **/**, I have a word to add this.
And then a word that constructs a filename.

This also has a word `check-for-params` that is used to separate
the requested file from any query string that may be present.

~~~
:map-/-to-index (-)
  &Requested '/ s:eq?
    [ '/index.html &Requested s:copy ] if ;

:ensure-leading-/ (-)
  @Requested $/ -eq?
    [ '/ &Requested s:append s:keep &Requested s:copy ] if ;

:check-for-params (-)
  &Requested $? s:contains-char?
    [ &Requested $? s:split drop dup n:inc !GET-Query #0 swap store ] if ;

:filename (-s)
  check-for-params map-/-to-index ensure-leading-/
  &Requested &Host WEBROOT '%s/%s%s s:format ;
~~~

Next, I need to determine the file type. I'll do this by taking
a look at the extension, and mapping this to a MIME type.

~~~
:filename-w/o-path
  WEBROOT s:length &Host s:length + filename +
  [ $/ s:index-of ] sip + ;

:get-mime-type (-s)
  filename-w/o-path [ $. s:index-of ] sip +
  (fsp)
    '.fsp   [ 'application/fsp          ] s:case
  (textual_files)
    '.txt   [ 'text/plain               ] s:case
    '.md    [ 'text/markdown            ] s:case
    '.htm   [ 'text/html                ] s:case
    '.html  [ 'text/html                ] s:case
    '.css   [ 'text/css                 ] s:case
    '.c     [ 'text/plain               ] s:case
    '.h     [ 'text/plain               ] s:case
    '.forth [ 'text/plain               ] s:case
    '.retro [ 'text/plain               ] s:case
  (image_files)
    '.png   [ 'image/png                ] s:case
    '.jpg   [ 'image/jpeg               ] s:case
    '.jpeg  [ 'image/jpeg               ] s:case
    '.gif   [ 'image/gif                ] s:case
    '.bmp   [ 'image/bmp                ] s:case
  (application_files)
    '.pdf   [ 'application/pdf          ] s:case
    '.gz    [ 'application/gzip         ] s:case
    '.zip   [ 'application/zip          ] s:case
    '.json  [ 'application/json         ] s:case
    '.js    [ 'application/x-javascript ] s:case
    '.xml   [ 'application/xml          ] s:case
  drop 'text/plain ;
~~~

Using these, I can construct a word to read in the file and
send it to the client.

Reading files is now a bit more involved, since images and
other formats have binary data.

If the mime type is application/fsp, this will run the code
in the file. The code should output the necessary headers
and content.

~~~
'FID var

:read-file (-an)
  here
  filename file:R file:open !FID
  @FID file:size [ [ @FID file:read , ] times ] sip
  @FID file:close ;

:eol  (-)   ASCII:CR c:put ASCII:LF c:put ;

:send-file (-)
  get-mime-type
  dup 'application/fsp s:eq?
  [ drop filename include ]
  [ 'Content_type:_%s s:format s:put eol eol
    read-file [ fetch-next c:put ] times drop ] choose ;
~~~

In the above, `eol` will send an end of line sequence.

The last support word is a handler for 404 errors. This
will send the 404 status code and a human readable error
message.

~~~
:404 'HTTP/1.1_404_OK s:put eol
     'Content-type:_text/html s:put eol eol
     'ERROR_404:_FILE_NOT_FOUND s:put eol ;
~~~

And now for the top level server.

Receive a request:

~~~
read-request
~~~

See if the file exists:

~~~
filename file:exists?
~~~

Send an "200 OK" response and the file (or a 404 if
the file wasn't found):

~~~
[ 'HTTP/1.1_200_OK s:put eol send-file ]
[ 404 ] choose
~~~

And the code for Casket is done.

----

## Using Casket

Casket requires [Retro](http://forthworks.com/retro) and a Unix system with inetd.

Install Retro and put the `casket.forth` somewhere. Then add a configuration line to your `/etc/inetd.conf`. I use:

    http    stream  tcp     nowait/6/30/2   casket    /home/crc/servers/casket.forth

Restart inetd.

Edit the `WEBROOT` in `casket.forth` to point to your web directory. Then go to the web directory and create a directory for each domain. E.g.,

    /home/crc/www/casket.forthworks.com

Put your `index.html` and other files here and try accessing your website.

## Download

* [casket.forth](http://forth.works:8080/casket.forth)
* [retro forth](http://forthworks.com/r/latest.tar.gz)

----

## Real World Uses

Casket has been in use since the second half of 2018 serving a number of small websites. It's also used to host the Casket project page you are looking at.

---

## License and Copyright

Copyright (c) 2018 - 2019, Charles Childers

Permission to use, copy, modify, and/or distribute this software
for any purpose with or without fee is hereby granted, provided
that the copyright notice and this permission notice appear in
all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
OF THIS SOFTWARE.