modules/media: Add preview_url stub-plus.

modules/Makefile.am

@@ -283,6 +283,7 @@ media_media_media_la_SOURCES = \
 	media/download.cc \
 	media/upload.cc \
 	media/thumbnail.cc \
+	media/preview_url.cc \
 	media/media.cc \
 	###
 

modules/media/preview_url.cc

@@ -0,0 +1,163 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#include "media.h"
+
+resource
+preview_url_resource
+{
+	"/_matrix/media/r0/preview_url",
+	{
+		"(11.7.1.5) Get information about a URL for a client"
+	}
+};
+
+static unique_buffer<mutable_buffer>
+request_url(const string_view &urle);
+
+static json::strung
+parse_og(const string_view &content);
+
+static resource::response
+get__preview_url(client &client,
+                 const resource::request &request)
+{
+	const auto &url
+	{
+		request.query.at("url")
+	};
+
+	const auto &ts
+	{
+		request.query.get("ts", milliseconds(-1))
+	};
+
+	const unique_buffer<mutable_buffer> content_buffer
+	{
+		//request_url(url)
+	};
+
+	const string_view content
+	{
+		content_buffer
+	};
+
+	const json::strung ogs
+	{
+		parse_og(content)
+	};
+
+	return resource::response
+	{
+		client, json::object{ogs}
+	};
+}
+
+static resource::method
+method_get
+{
+	preview_url_resource, "GET", get__preview_url
+};
+
+json::strung
+parse_og(const string_view &content)
+{
+	std::vector<json::member> og;
+
+	return
+	{
+		og.data(), og.data() + og.size()
+	};
+}
+
+unique_buffer<mutable_buffer>
+request_url(const string_view &urle)
+{
+	const unique_buffer<mutable_buffer> buf
+	{
+		24_KiB
+	};
+
+	const auto url
+	{
+		url::decode(urle, buf)
+	};
+
+	const auto &host
+	{
+		between(url, "://", "/")  //TODO: grammar / rfc3986.h
+	};
+
+	const string_view &service
+	{
+		split(url, "://").first
+	};
+
+	const string_view &path
+	{
+		end(host), end(url)
+	};
+
+	if(empty(host) || empty(path))
+		throw m::error
+		{
+			http::BAD_REQUEST, "M_BAD_URL",
+			"Something was wrong with the supplied URL."
+		};
+
+	window_buffer wb
+	{
+		buf + size(url)
+	};
+
+	http::request
+	{
+		wb, host, "GET", path, 0, {},
+		{
+			{ "User-Agent", info::user_agent },
+		}
+	};
+
+	const const_buffer out_head
+	{
+		wb.completed()
+	};
+
+	const mutable_buffer in_head
+	{
+		buf + size(url) + size(out_head)
+	};
+
+	const net::hostport remote
+	{
+		//TODO: fix services translation in net::dns::
+		host, {}, service == "https"? uint16_t(443) : uint16_t(80)
+	};
+
+	server::request::opts sopts;
+	sopts.http_exceptions = false;
+	server::request request
+	{
+		remote, { out_head }, { in_head, mutable_buffer{} }, &sopts
+	};
+
+	request.wait(seconds(10)); //TODO: conf
+
+	const auto code
+	{
+		request.get()
+	};
+
+	if(code != http::OK)
+		return {};
+
+	assert(data(request.in.content) == data(request.in.dynamic));
+	return std::move(request.in.dynamic);
+}