PHP Proxy 负载均衡技术

<?php

$whitelistPatterns = array(

);

$forceCORS = false;

$anonymize = true;

$startURL = "";

$landingExampleURL = "https://example.net";

/****************************** END CONFIGURATION ******************************/

ob_start("ob_gzhandler");

if (version_compare(PHP_VERSION, "5.4.7", "<")) {

  die("miniProxy requires PHP version 5.4.7 or later.");

}

$requiredExtensions = ["curl", "mbstring", "xml"];

foreach($requiredExtensions as $requiredExtension) {

  if (!extension_loaded($requiredExtension)) {

    die("miniProxy requires PHP's \"" . $requiredExtension . "\" extension. Please install/enable it on your server and try again.");

  }

}

function getHostnamePattern($hostname) {

  $escapedHostname = str_replace(".", "\.", $hostname);

  return "@^https?://([a-z0-9-]+\.)*" . $escapedHostname . "@i";

}

//Helper function used to removes/unset keys from an associative array using case insensitive matching

function removeKeys(&$assoc, $keys2remove) {

  $keys = array_keys($assoc);

  $map = array();

  $removedKeys = array();

  foreach ($keys as $key) {

    $map[strtolower($key)] = $key;

  }

  foreach ($keys2remove as $key) {

    $key = strtolower($key);

    if (isset($map[$key])) {

      unset($assoc[$map[$key]]);

      $removedKeys[] = $map[$key];

    }

  }

  return $removedKeys;

}

if (!function_exists("getallheaders")) {

  //Adapted from http://www.php.net/manual/en/function.getallheaders.php#99814

  function getallheaders() {

    $result = array();

    foreach($_SERVER as $key => $value) {

      if (substr($key, 0, 5) == "HTTP_") {

        $key = str_replace(" ", "-", ucwords(strtolower(str_replace("_", " ", substr($key, 5)))));

        $result[$key] = $value;

      }

    }

    return $result;

  }

}

$usingDefaultPort =  (!isset($_SERVER["HTTPS"]) && $_SERVER["SERVER_PORT"] === 80) || (isset($_SERVER["HTTPS"]) && $_SERVER["SERVER_PORT"] === 443);

$prefixPort = $usingDefaultPort ? "" : ":" . $_SERVER["SERVER_PORT"];

//Use HTTP_HOST to support client-configured DNS (instead of SERVER_NAME), but remove the port if one is present

$prefixHost = $_SERVER["HTTP_HOST"];

$prefixHost = strpos($prefixHost, ":") ? implode(":", explode(":", $_SERVER["HTTP_HOST"], -1)) : $prefixHost;

define("PROXY_PREFIX", "http" . (isset($_SERVER["HTTPS"]) ? "s" : "") . "://" . $prefixHost . $prefixPort . $_SERVER["SCRIPT_NAME"] . "?");

//Makes an HTTP request via cURL, using request data that was passed directly to this script.

function makeRequest($url) {

  global $anonymize;

  //Tell cURL to make the request using the brower's user-agent if there is one, or a fallback user-agent otherwise.

  $user_agent = $_SERVER["HTTP_USER_AGENT"];

  if (empty($user_agent)) {

    $user_agent = "Mozilla/5.0 (compatible; miniProxy)";

  }

  $ch = curl_init();

  curl_setopt($ch, CURLOPT_USERAGENT, $user_agent);

  //Get ready to proxy the browser's request headers...

  $browserRequestHeaders = getallheaders();

  //...but let cURL set some headers on its own.

  $removedHeaders = removeKeys($browserRequestHeaders, array(

    "Accept-Encoding", //Throw away the browser's Accept-Encoding header if any and let cURL make the request using gzip if possible.

    "Content-Length",

    "Host",

    "Origin"

  ));

  $removedHeaders = array_map("strtolower", $removedHeaders);

  curl_setopt($ch, CURLOPT_ENCODING, "");

  //Transform the associative array from getallheaders() into an

  //indexed array of header strings to be passed to cURL.

  $curlRequestHeaders = array();

  foreach ($browserRequestHeaders as $name => $value) {

    $curlRequestHeaders[] = $name . ": " . $value;

  }

  if (!$anonymize) {

    $curlRequestHeaders[] = "X-Forwarded-For: " . $_SERVER["REMOTE_ADDR"];

  }

  //Any `origin` header sent by the browser will refer to the proxy itself.

  //If an `origin` header is present in the request, rewrite it to point to the correct origin.

  if (in_array("origin", $removedHeaders)) {

    $urlParts = parse_url($url);

    $port = $urlParts["port"];

    $curlRequestHeaders[] = "Origin: " . $urlParts["scheme"] . "://" . $urlParts["host"] . (empty($port) ? "" : ":" . $port);

  };

  curl_setopt($ch, CURLOPT_HTTPHEADER, $curlRequestHeaders);

  //Proxy any received GET/POST/PUT data.

  switch ($_SERVER["REQUEST_METHOD"]) {

    case "POST":

      curl_setopt($ch, CURLOPT_POST, true);

      $postData = Array();

      parse_str(file_get_contents("php://input"), $postData);

      if (isset($postData["miniProxyFormAction"])) {

        unset($postData["miniProxyFormAction"]);

      }

      curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($postData));

    break;

    case "PUT":

      curl_setopt($ch, CURLOPT_PUT, true);

      curl_setopt($ch, CURLOPT_INFILE, fopen("php://input", "r"));

    break;

  }

  //Other cURL options.

  curl_setopt($ch, CURLOPT_HEADER, true);

  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

  //Set the request URL.

  curl_setopt($ch, CURLOPT_URL, $url);

  //Make the request.

  $response = curl_exec($ch);

  $responseInfo = curl_getinfo($ch);

  $headerSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);

  curl_close($ch);

  //Setting CURLOPT_HEADER to true above forces the response headers and body

  //to be output together--separate them.

  $responseHeaders = substr($response, 0, $headerSize);

  $responseBody = substr($response, $headerSize);

  return array("headers" => $responseHeaders, "body" => $responseBody, "responseInfo" => $responseInfo);

}

//Converts relative URLs to absolute ones, given a base URL.

//Modified version of code found at http://nashruddin.com/PHP_Script_for_Converting_Relative_to_Absolute_URL

function rel2abs($rel, $base) {

  if (empty($rel)) $rel = ".";

  if (parse_url($rel, PHP_URL_SCHEME) != "" || strpos($rel, "//") === 0) return $rel; //Return if already an absolute URL

  if ($rel[0] == "#" || $rel[0] == "?") return $base.$rel; //Queries and anchors

  extract(parse_url($base)); //Parse base URL and convert to local variables: $scheme, $host, $path

  $path = isset($path) ? preg_replace("#/[^/]*$#", "", $path) : "/"; //Remove non-directory element from path

  if ($rel[0] == "/") $path = ""; //Destroy path if relative url points to root

  $port = isset($port) && $port != 80 ? ":" . $port : "";

  $auth = "";

  if (isset($user)) {

    $auth = $user;

    if (isset($pass)) {

      $auth .= ":" . $pass;

    }

    $auth .= "@";

  }

  $abs = "$auth$host$port$path/$rel"; //Dirty absolute URL

  for ($n = 1; $n > 0; $abs = preg_replace(array("#(/\.?/)#", "#/(?!\.\.)[^/]+/\.\./#"), "/", $abs, -1, $n)) {} //Replace '//' or '/./' or '/foo/../' with '/'

  return $scheme . "://" . $abs; //Absolute URL is ready.

}

//Proxify contents of url() references in blocks of CSS text.

function proxifyCSS($css, $baseURL) {

  $sourceLines = explode("\n", $css);

  $normalizedLines = [];

  foreach ($sourceLines as $line) {

    if (preg_match("/@import\s+url/i", $line)) {

      $normalizedLines[] = $line;

    } else {

      $normalizedLines[] = preg_replace_callback(

        "/(@import\s+)([^;\s]+)([\s;])/i",

        function($matches) use ($baseURL) {

          return $matches[1] . "url(" . $matches[2] . ")" . $matches[3];

        },

        $line);

    }

  }

  $normalizedCSS = implode("\n", $normalizedLines);

  return preg_replace_callback(

    "/url\((.*?)\)/i",

    function($matches) use ($baseURL) {

        $url = $matches[1];

        if (strpos($url, "'") === 0) {

          $url = trim($url, "'");

        }

        if (strpos($url, "\"") === 0) {

          $url = trim($url, "\"");

        }

        if (stripos($url, "data:") === 0) return "url(" . $url . ")"; //The URL isn't an HTTP URL but is actual binary data. Don't proxify it.

        return "url(" . PROXY_PREFIX . rel2abs($url, $baseURL) . ")";

    },

    $normalizedCSS);

}

//Proxify "srcset" attributes (normally associated with <img> tags.)

function proxifySrcset($srcset, $baseURL) {

  $sources = array_map("trim", explode(",", $srcset)); //Split all contents by comma and trim each value

  $proxifiedSources = array_map(function($source) use ($baseURL) {

    $components = array_map("trim", str_split($source, strrpos($source, " "))); //Split by last space and trim

    $components[0] = PROXY_PREFIX . rel2abs(ltrim($components[0], "/"), $baseURL); //First component of the split source string should be an image URL; proxify it

    return implode($components, " "); //Recombine the components into a single source

  }, $sources);

  $proxifiedSrcset = implode(", ", $proxifiedSources); //Recombine the sources into a single "srcset"

  return $proxifiedSrcset;

}

//Extract and sanitize the requested URL, handling cases where forms have been rewritten to point to the proxy.

if (isset($_POST["miniProxyFormAction"])) {

  $url = $_POST["miniProxyFormAction"];

  unset($_POST["miniProxyFormAction"]);

} else {

  $queryParams = Array();

  parse_str($_SERVER["QUERY_STRING"], $queryParams);

  //If the miniProxyFormAction field appears in the query string, make $url start with its value, and rebuild the the query string without it.

  if (isset($queryParams["miniProxyFormAction"])) {

    $formAction = $queryParams["miniProxyFormAction"];

    unset($queryParams["miniProxyFormAction"]);

    $url = $formAction . "?" . http_build_query($queryParams);

  } else {

    $url = substr($_SERVER["REQUEST_URI"], strlen($_SERVER["SCRIPT_NAME"]) + 1);

  }

}

if (empty($url)) {

    if (empty($startURL)) {

      die("<html><head><title>miniProxy</title></head><body><h1>Welcome to miniProxy!</h1>miniProxy can be directly invoked like this: <a href=\"" . PROXY_PREFIX . $landingExampleURL . "\">" . PROXY_PREFIX . $landingExampleURL . "</a><br /><br />Or, you can simply enter a URL below:<br /><br /><form onsubmit=\"if (document.getElementById('site').value) { window.location.href='" . PROXY_PREFIX . "' + document.getElementById('site').value; return false; } else { window.location.href='" . PROXY_PREFIX . $landingExampleURL . "'; return false; }\" autocomplete=\"off\"><input id=\"site\" type=\"text\" size=\"50\" /><input type=\"submit\" value=\"Proxy It!\" /></form></body></html>");

    } else {

      $url = $startURL;

    }

} else if (strpos($url, ":/") !== strpos($url, "://")) {

    $pos = strpos($url, ":/");

    $url = substr_replace($url, "://", $pos, strlen(":/"));

}

$scheme = parse_url($url, PHP_URL_SCHEME);

if (empty($scheme)) {

  //Assume that any supplied URLs starting with // are HTTP URLs.

  if (strpos($url, "//") === 0) {

    $url = "http:" . $url;

  }

} else if (!preg_match("/^https?$/i", $scheme)) {

    die('Error: Detected a "' . $scheme . '" URL. miniProxy exclusively supports http[s] URLs.');

}

//Validate the requested URL against the whitelist.

$urlIsValid = count($whitelistPatterns) === 0;

foreach ($whitelistPatterns as $pattern) {

  if (preg_match($pattern, $url)) {

    $urlIsValid = true;

    break;

  }

}

if (!$urlIsValid) {

  die("Error: The requested URL was disallowed by the server administrator.");

}

$response = makeRequest($url);

$rawResponseHeaders = $response["headers"];

$responseBody = $response["body"];

$responseInfo = $response["responseInfo"];

//If CURLOPT_FOLLOWLOCATION landed the proxy at a diferent URL than

//what was requested, explicitly redirect the proxy there.

$responseURL = $responseInfo["url"];

if ($responseURL !== $url) {

  header("Location: " . PROXY_PREFIX . $responseURL, true);

  exit(0);

}

//A regex that indicates which server response headers should be stripped out of the proxified response.

$header_blacklist_pattern = "/^Content-Length|^Transfer-Encoding|^Content-Encoding.*gzip/i";

$responseHeaderBlocks = array_filter(explode("\r\n\r\n", $rawResponseHeaders));

$lastHeaderBlock = end($responseHeaderBlocks);

$headerLines = explode("\r\n", $lastHeaderBlock);

foreach ($headerLines as $header) {

  $header = trim($header);

  if (!preg_match($header_blacklist_pattern, $header)) {

    header($header, false);

  }

}

//Prevent robots from indexing proxified pages

header("X-Robots-Tag: noindex, nofollow", true);

if ($forceCORS) {

  header("Access-Control-Allow-Origin: *", true);

  header("Access-Control-Allow-Credentials: true", true);

  //Handle CORS headers received during OPTIONS requests.

  if ($_SERVER["REQUEST_METHOD"] == "OPTIONS") {

    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_METHOD"])) {

      header("Access-Control-Allow-Methods: GET, POST, OPTIONS", true);

    }

    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"])) {

      header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}", true);

    }

    //No further action is needed for OPTIONS requests.

    exit(0);

  }

}

$contentType = "";

if (isset($responseInfo["content_type"])) $contentType = $responseInfo["content_type"];

//This is presumably a web page, so attempt to proxify the DOM.

if (stripos($contentType, "text/html") !== false) {

  //Attempt to normalize character encoding.

  $detectedEncoding = mb_detect_encoding($responseBody, "UTF-8, ISO-8859-1");

  if ($detectedEncoding) {

    $responseBody = mb_convert_encoding($responseBody, "HTML-ENTITIES", $detectedEncoding);

  }

  //Parse the DOM.

  $doc = new DomDocument();

  @$doc->loadHTML($responseBody);

  $xpath = new DOMXPath($doc);

  //Rewrite forms so that their actions point back to the proxy.

  foreach($xpath->query("//form") as $form) {

    $method = $form->getAttribute("method");

    $action = $form->getAttribute("action");

    //If the form doesn't have an action, the action is the page itself.

    //Otherwise, change an existing action to an absolute version.

    $action = empty($action) ? $url : rel2abs($action, $url);

    //Rewrite the form action to point back at the proxy.

    $form->setAttribute("action", rtrim(PROXY_PREFIX, "?"));

    //Add a hidden form field that the proxy can later use to retreive the original form action.

    $actionInput = $doc->createDocumentFragment();

    $actionInput->appendXML('<input type="hidden" name="miniProxyFormAction" value="' . htmlspecialchars($action) . '" />');

    $form->appendChild($actionInput);

  }

  //Proxify <meta> tags with an 'http-equiv="refresh"' attribute.

  foreach ($xpath->query("//meta[@http-equiv]") as $element) {

    if (strcasecmp($element->getAttribute("http-equiv"), "refresh") === 0) {

      $content = $element->getAttribute("content");

      if (!empty($content)) {

        $splitContent = preg_split("/=/", $content);

        if (isset($splitContent[1])) {

          $element->setAttribute("content", $splitContent[0] . "=" . PROXY_PREFIX . rel2abs($splitContent[1], $url));

        }

      }

    }

  }

  //Profixy <style> tags.

  foreach($xpath->query("//style") as $style) {

    $style->nodeValue = proxifyCSS($style->nodeValue, $url);

  }

  //Proxify tags with a "style" attribute.

  foreach ($xpath->query("//*[@style]") as $element) {

    $element->setAttribute("style", proxifyCSS($element->getAttribute("style"), $url));

  }

  //Proxify "srcset" attributes in <img> tags.

  foreach ($xpath->query("//img[@srcset]") as $element) {

    $element->setAttribute("srcset", proxifySrcset($element->getAttribute("srcset"), $url));

  }

  //Proxify any of these attributes appearing in any tag.

  $proxifyAttributes = array("href", "src");

  foreach($proxifyAttributes as $attrName) {

    foreach($xpath->query("//*[@" . $attrName . "]") as $element) { //For every element with the given attribute...

      $attrContent = $element->getAttribute($attrName);

      if ($attrName == "href" && preg_match("/^(about|javascript|magnet|mailto):|#/i", $attrContent)) continue;

      if ($attrName == "src" && preg_match("/^(data):/i", $attrContent)) continue;

      $attrContent = rel2abs($attrContent, $url);

      $attrContent = PROXY_PREFIX . $attrContent;

      $element->setAttribute($attrName, $attrContent);

    }

  }

  $head = $xpath->query("//head")->item(0);

  $body = $xpath->query("//body")->item(0);

  $prependElem = $head != null ? $head : $body;

  if ($prependElem != null) {

    $scriptElem = $doc->createElement("script",

      '(function() {

        if (window.XMLHttpRequest) {

          function parseURI(url) {

            var m = String(url).replace(/^\s+|\s+$/g, "").match(/^([^:\/?#]+:)?(\/\/(?:[^:@]*(?::[^:@]*)?@)?(([^:\/?#]*)(?::(\d*))?))?([^?#]*)(\?[^#]*)?(#[\s\S]*)?/);

            // authority = "//" + user + ":" + pass "@" + hostname + ":" port

            return (m ? {

              href : m[0] || "",

              protocol : m[1] || "",

              authority: m[2] || "",

              host : m[3] || "",

              hostname : m[4] || "",

              port : m[5] || "",

              pathname : m[6] || "",

              search : m[7] || "",

              hash : m[8] || ""

            } : null);

          }

          function rel2abs(base, href) { // RFC 3986

            function removeDotSegments(input) {

              var output = [];

              input.replace(/^(\.\.?(\/|$))+/, "")

                .replace(/\/(\.(\/|$))+/g, "/")

                .replace(/\/\.\.$/, "/../")

                .replace(/\/?[^\/]*/g, function (p) {

                  if (p === "/..") {

                    output.pop();

                  } else {

                    output.push(p);

                  }

                });

              return output.join("").replace(/^\//, input.charAt(0) === "/" ? "/" : "");

            }

            href = parseURI(href || "");

            base = parseURI(base || "");

            return !href || !base ? null : (href.protocol || base.protocol) +

            (href.protocol || href.authority ? href.authority : base.authority) +

            removeDotSegments(href.protocol || href.authority || href.pathname.charAt(0) === "/" ? href.pathname : (href.pathname ? ((base.authority && !base.pathname ? "/" : "") + base.pathname.slice(0, base.pathname.lastIndexOf("/") + 1) + href.pathname) : base.pathname)) +

            (href.protocol || href.authority || href.pathname ? href.search : (href.search || base.search)) +

            href.hash;

          }

          var proxied = window.XMLHttpRequest.prototype.open;

          window.XMLHttpRequest.prototype.open = function() {

              if (arguments[1] !== null && arguments[1] !== undefined) {

                var url = arguments[1];

                url = rel2abs("' . $url . '", url);

                if (url.indexOf("' . PROXY_PREFIX . '") == -1) {

                  url = "' . PROXY_PREFIX . '" + url;

                }

                arguments[1] = url;

              }

              return proxied.apply(this, [].slice.call(arguments));

          };

        }

      })();'

    );

    $scriptElem->setAttribute("type", "text/javascript");

    $prependElem->insertBefore($scriptElem, $prependElem->firstChild);

  }

  echo "<!-- Proxified page constructed by miniProxy -->\n" . $doc->saveHTML();

} else if (stripos($contentType, "text/css") !== false) { //This is CSS, so proxify url() references.

  echo proxifyCSS($responseBody, $url);

} else { //This isn't a web page or CSS, so serve unmodified through the proxy with the correct headers (images, JavaScript, etc.)

  header("Content-Length: " . strlen($responseBody), true);

  echo $responseBody;

}