init.php

<?php
class HTTPS_Proxy extends Plugin {

	/* @var PluginHost $host */
	private $host;

	/* @var DiskCache $cache */
	private $cache;

	function about() {
		return array(1.0,
			"Proxies all requests via built-in secure proxy",
			"fox, timendum");
	}

	function is_public_method($method) {
		return $method === "urlproxy";
	}

	function init($host) {
		$this->host = $host;
		$this->cache = DiskCache::instance("urlproxy");
		$this->cache->make_dir();

		$host->add_hook($host::HOOK_RENDER_ARTICLE, $this, 150);
		$host->add_hook($host::HOOK_RENDER_ARTICLE_CDM, $this, 150);
		$host->add_hook($host::HOOK_RENDER_ARTICLE_API, $this, 150);

		$host->add_hook($host::HOOK_ENCLOSURE_ENTRY, $this);

		$host->add_hook($host::HOOK_PREFS_TAB, $this);
	}

        function hook_enclosure_entry($enc, $article_id, $rv) {
		if (preg_match("/image/", $enc["content_type"])) {
			$enc["content_url"] = $this->rewrite_url_if_needed($enc["content_url"]);
		}

		return $enc;
	}

	function hook_render_article($article) {
		return $this->hook_render_article_cdm($article);
	}

	function hook_render_article_api($row) {
		$article = isset($row['headline']) ? $row['headline'] : $row['article'];
		return $this->hook_render_article_cdm($article);
	}

	public function urlproxy() {

		$url = rewrite_relative_url(Config::get_self_url(), $_REQUEST["url"]);

		// called without user context, let's just redirect to original URL
		if (!$_SESSION["uid"]) {
			header("Location: $url");
			return;
		}

		$local_filename = sha1($url);

		if ($this->cache->exists($local_filename)) {
			header("Location: " . $this->cache->get_url($local_filename));
			return;
			//$this->cache->send($local_filename);
		} else {
			$data = fetch_file_contents(["url" => $url, "max_size" => Config::get(Config::MAX_CACHE_FILE_SIZE)]);

			if ($data) {

				$disable_cache = $this->host->get($this, "disable_cache");

				if (!$disable_cache) {
					if ($this->cache->put($local_filename, $data)) {
						header("Location: " . $this->cache->get_url($local_filename));
						return;
					}
				}

				print $data;
			} else {
				global $fetch_last_error;
				global $fetch_last_error_code;
				global $fetch_last_error_content;

				if (function_exists("imagecreate") && !isset($_REQUEST["text"])) {
					$img = imagecreate(450, 75);

					/*$bg =*/ imagecolorallocate($img, 255, 255, 255);
					$textcolor = imagecolorallocate($img, 255, 0, 0);

					imagerectangle($img, 0, 0, 450-1, 75-1, $textcolor);

					imagestring($img, 5, 5, 5, "Proxy request failed", $textcolor);
					imagestring($img, 5, 5, 30, truncate_middle($url, 46, "..."), $textcolor);
					imagestring($img, 5, 5, 55, "HTTP Code: $fetch_last_error_code", $textcolor);

					header("Content-type: image/png");
					print imagepng($img);
					imagedestroy($img);

				} else {
					header("Content-type: text/html");

					http_response_code(400);

					print "<h1>Proxy request failed.</h1>";
					print "<p>Fetch error $fetch_last_error ($fetch_last_error_code)</p>";
					print "<p>URL: $url</p>";
					print "<textarea cols='80' rows='25'>" . htmlspecialchars($fetch_last_error_content) . "</textarea>";
				}
			}
		}
	}

	private function rewrite_url_if_needed($url) {
		$local_filename = sha1($url);
		if ($this->cache->exists($local_filename)) {
			return $this->cache->get_url($local_filename);
		}

		$whitelist = $this->host->get($this, "whitelist");
		if (strpos($url, "data:") !== 0) {
			$parts = parse_url($url);

			foreach (explode(" " , $whitelist) as $host) {
				if (substr(strtolower($parts['host']), -strlen($host)) === strtolower($host)) {
					return $url;
				}
			}

			return $this->host->get_public_method_url($this, "urlproxy", ["url" => $url]);
		}
	}

	/**
	 * @SuppressWarnings(PHPMD.UnusedFormalParameter)
	 */
	function hook_render_article_cdm($article, $api_mode = false) {

		$need_saving = false;

		$doc = new DOMDocument();
		if (@$doc->loadHTML('<?xml encoding="UTF-8">' . $article["content"])) {
			$xpath = new DOMXPath($doc);
			$imgs = $xpath->query("//img[@src]");

			foreach ($imgs as $img) {
				$new_src = $this->rewrite_url_if_needed($img->getAttribute("src"));

				if ($new_src != $img->getAttribute("src")) {
					$img->setAttribute("src", $new_src);
					$img->removeAttribute("srcset");

					$need_saving = true;
				}
			}

			$vids = $xpath->query("(//video|//picture)");

			foreach ($vids as $vid) {
				if ($vid->hasAttribute("poster")) {
					$new_src = $this->rewrite_url_if_needed($vid->getAttribute("poster"));

					if ($new_src != $vid->getAttribute("poster")) {
						$vid->setAttribute("poster", $new_src);

						$need_saving = true;
					}
				}

				$vsrcs = $xpath->query("source", $vid);

				foreach ($vsrcs as $vsrc) {
					$new_src = $this->rewrite_url_if_needed($vsrc->getAttribute("src"));

					if ($new_src != $vsrc->getAttribute("src")) {
						$vid->setAttribute("src", $new_src);

						$need_saving = true;
					}
				}
			}
		}

		if ($need_saving) $article["content"] = $doc->saveHTML();

		return $article;
	}

	function hook_prefs_tab($args) {
                if ($args != "prefFeeds") return;

                $disable_cache = $this->host->get($this, "disable_cache");
                $whitelist = $this->host->get($this, "whitelist");
?>
                <div dojoType="dijit.layout.AccordionPane"
                        title="<i class='material-icons'>extension</i> <?= __('HTTPS Proxy settings (https_proxy)') ?>">

                        <form dojoType='dijit.form.Form'>

                                <?= \Controls\pluginhandler_tags($this, "save") ?>

                                <script type="dojo/method" event="onSubmit" args="evt">
                                        evt.preventDefault();
                                        if (this.validate()) {
                                                Notify.progress('Saving data...', true);
                                                xhr.post("backend.php", this.getValues(), (reply) => {
                                                        Notify.info(reply);
                                                })
                                        }
                                </script>

                                <fieldset class='narrow'>
                                        <label class='checkbox'>
                                                <?= \Controls\checkbox_tag("disable_cache", $disable_cache) ?>
                                                <?= __("Don't cache files locally") ?>
                                        </label>
                                </fieldset>
                                <fieldset class='narrow'>
                                        <label>
                                                <?= __("Don't proxy these hosts (space-separated list):") ?>
                                        </label>
                                        <input dojoType="dijit.form.TextBox" name="whitelist" size="20"
                                                value="<?= $whitelist ?>">
                                </fieldset>

                                <hr/>
                                <?= \Controls\submit_tag(__("Save")) ?>
                        </form>
                </div>
<?php
        }


	function save() {
		$disable_cache = checkbox_to_sql_bool($_POST["disable_cache"]);
		$whitelist = trim(strip_tags($_POST["whitelist"]));

		$this->host->set($this, "disable_cache", $disable_cache);
		$this->host->set($this, "whitelist", $whitelist);

		echo __("Configuration saved");
	}

	function api_version() {
		return 2;
	}
}
?>