183 lines
5.1 KiB
Forth
183 lines
5.1 KiB
Forth
#!/bin/sh
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cd /home/crc/gemini
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retro atua-gemini
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exit
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---------------------------------------------------------------
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This is Atua-Gemini, my Gemini server in RetroForth.
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As with most of my servers, it runs under inetd, and is only
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built to meet my needs.
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The relevant parts of the Gemini spec are included here. I'm
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using 0.14.3, taken from
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https://gemini.circumlunar.space/docs/specification.html
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---------------------------------------------------------------
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1.1 Gemini transactions
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There is one kind of Gemini transaction, roughly equivalent to
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a gopher request or a HTTP "GET" request. Transactions happen
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as follows:
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C: Opens connection
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S: Accepts connection
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C/S: Complete TLS handshake (see section 4)
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C: Validates server certificate (see 4.2)
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C: Sends request (one CRLF terminated line) (see section 2)
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S: Sends response header (one CRLF terminated line), closes
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connection under non-success conditions (see 3.1 & 3.2)
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S: Sends response body (text or binary data) (see 3.3)
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S: Closes connection
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C: Handles response (see 3.4)
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---------------------------------------------------------------
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~~~
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:eol ASCII:CR ASCII:LF [ c:put ] bi@ ;
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~~~
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I am delegating the connection handling to inetd and the TLS
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handling to ssltunnel. So all I need to handle is the request
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itself.
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Reading the request is just a matter of:
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~~~
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'Request var
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:request s:get s:keep &Request store ;
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~~~
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---------------------------------------------------------------
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1.2 Gemini URI scheme
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Resources hosted via Gemini are identified using URIs with the
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scheme "gemini". This scheme is syntactically compatible with
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the generic URI syntax defined in RFC 3986, but does not
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support all components of the generic syntax. In particular,
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the authority component is allowed and required, but its
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userinfo subcomponent is NOT allowed. The host subcomponent
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is required. The port subcomponent is optional, with a default
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value of 1965. The path, query and fragment components are
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allowed and have no special meanings beyond those defined by
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the generic syntax. Spaces in gemini URIs should be encoded as
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%20, not +.
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---------------------------------------------------------------
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From the RFC 3986:
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The following are two example URIs and their component parts:
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foo://example.com:8042/over/there?name=ferret#nose
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\_/ \______________/\_________/ \_________/ \__/
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| | | | |
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scheme authority path query fragment
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| _____________________|__
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/ \ / \
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urn:example:animal:ferret:nose
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~~~
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'Scheme var
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'Authority var
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'Port var
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'Path var
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'Query var
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'Fragment var
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:uri:parse #9 + s:keep !Path ;
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~~~
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---------------------------------------------------------------
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3 Gemini responses
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Gemini response consist of a single CRLF-terminated header
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line, optionally followed by a response body.
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3.1 Response headers
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Gemini response headers look like this:
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<STATUS><SPACE><META><CR><LF>
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<STATUS> is a two-digit numeric status code, as described
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below in 3.2 and in Appendix 1.
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<SPACE> is a single space character, i.e. the byte 0x20.
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<META> is a UTF-8 encoded string of maximum length 1024
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bytes, whose meaning is <STATUS> dependent.
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<STATUS> and <META> are separated by a single space
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character.
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If <STATUS> does not belong to the "SUCCESS" range of codes,
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then the server MUST close the connection after sending the
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header and MUST NOT send a response body.
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If a server sends a <STATUS> which is not a two-digit number or
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a <META> which exceeds 1024 bytes in length, the client SHOULD
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close the connection and disregard the response header,
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informing the user of an error.
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---------------------------------------------------------------
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I define constants for the statuses. Most of these won't be
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used by this server.
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~~~
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{ { '10 'status:INPUT }
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{ '11 'status:SENSITIVE-INPUT }
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{ '20 'status:SUCCESS }
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{ '30 'status:REDIRECT-TEMPORARY }
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{ '31 'status:REDIRECT-PERMANENT }
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{ '40 'status:TEMPORARY-FAILURE }
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{ '41 'status:SERVER-UNAVAILABLE }
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{ '42 'status:CGI-ERROR }
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{ '43 'status:PROXY-ERROR }
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{ '44 'status:SLOW-DOWN }
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{ '50 'status:PERMANENT-FAILURE }
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{ '51 'status:NOT-FOUND }
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{ '52 'status:GONE }
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{ '53 'status:PROXY-REQUEST-REFUSED }
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{ '59 'status:BAD-REQUEST }
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{ '60 'status:CLIENT-CERTIFICATE-REQUIRED }
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{ '61 'status:CERTIFICATE-NOT-AUTHORISED }
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{ '62 'status:CERTIFICATE-NOT-VALID }
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} [ [ ] a:for-each s:const ] a:for-each
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~~~
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~~~
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:status s:put ;
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:meta s:put ;
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:response status sp meta eol ;
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~~~
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---------------------------------------------------------------
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~~~
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:process
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@Request '/ s:ends-with? [ @Request 'index.gmi s:append s:keep !Request ] if
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@Request '.com s:ends-with? [ @Request '/index.gmi s:append s:keep !Request ] if
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@Request uri:parse
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@Path file:exists? [ FALSE 'Resource_not_found:_ @Path s:append status:NOT-FOUND ] -if;
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here @Path file:slurp here TRUE 'text/gemini status:SUCCESS ;
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~~~
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---------------------------------------------------------------
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~~~
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:serve
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request process response [ s:put ] if ;
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serve
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~~~
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