Typically to deal with HTTP I just use curl(1), but it is possible to make HTTP requests using the sockets vocabulary. It's just a pain to do so as HTTP has a lot of annoyances.

This example provides a way to make HTTP requests using only RETRO.

First, some variables. I'll keep the socket handle in Socket and the number of bytes read in Read.

~~~'Socket var 'Read   var ~~~

Since HTTP allows for a large number of response headers with various sizes and ordering, skipping them can be annoying. I do care about one: the Content-Length: result.

I'll track the number of sequential newlines in a variable named Seq, the value for Content-Length in Length, and then the current response line in Line.

As a bonus annoyance, HTTP doesn't limit the size of any particular header line, so I need to allocate enough space to cover anything it throws at me. Per a stackoverflow posting at https://stackoverflow.com/questions/686217/maximum-on-http-header-values I'll need at least 8KiB, so:

~~~'Length var 'Seq    var 'Line   var #8192 allot ~~~

Then skipping the headers is a matter of reading lines until two newlines are encountered.

~~~:read-byte    here #1 @Socket socket:recv drop-pair here fetch ; :append       dup buffer:add ; :eol?         [ ASCII:LF eq? ] [ ASCII:CR eq? ] bi or ; :is-length?   &Line 'Content-Length:_ s:begins-with? ; :process      &Line s:trim #16 + s:to-number !Length ; :next         &Line buffer:set ; :yes          &Seq v:inc ; :no           #0 !Seq ; :check        [ yes is-length? [ process ] if next ] [ no ] choose ; :read-line    read-byte append eol? check ; :done?        @Seq #4 eq? ; :skip-headers [ &Line buffer:set [ read-line done? ] until ] buffer:preserve ; ~~~

Now on to making the actual request to the server. An HTTP GET request takes a minimal form like:

GET HTTP/1.1 Host: domain

So I begin by writing a word to parse a URL. It'll store pointers to the parts in the Host and Request variables. This is pretty easy. I increase the starting point by 7 to skip over the HTTP:// part and then split on the first / character to separate the domain and requested file.

~~~'Host     var 'Request  var   :parse-url #7 + $/ s:split/char s:keep !Host s:keep !Request ; ~~~

Given that, making a request is simply:

~~~:make-request   @Host @Request   'GET_%s_HTTP/1.1\r\nHost:_%s\r\n\r\n s:format @Socket socket:send drop-pair ; ~~~

Moving on to reading the body, this is just reading bytes and shoving them into a buffer. I use the Read variable to track the number of bytes read, stopping when this reaches the Length extracted from the headers.

~~~:read-byte here #1 @Socket socket:recv drop-pair here fetch buffer:add ; :read-body [ &Read v:inc read-byte @Read @Length eq? ] until ; ~~~

And finally tieing this all together:

~~~:http:get (as-n)   parse-url   #0 !Seq #0 !Read   socket:create !Socket @Host '80 socket:configure   @Socket socket:connect drop-pair   [ buffer:set make-request skip-headers read-body ] buffer:preserve @Read ; ~~~

And a test case:

```'Body d:create #90000 allot &Body 'http://pestilenz.org/~ckeen/blog/posts/ciy-manifesto.html http:get &Body s:put ```