package com.btr.proxy.selector.pac;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.Proxy;
import java.net.URISyntaxException;
import java.net.URL;
import com.btr.proxy.util.Logger;
import com.btr.proxy.util.Logger.LogLevel;
import com.btr.proxy.util.MiscUtil;
/*****************************************************************************
* Script source that will load the content of a PAC file from an webserver.
* The script content is cached once it was downloaded.
*
* @author Bernd Rosstauscher (proxyvole@rosstauscher.de) Copyright 2009
****************************************************************************/
public class UrlPacScriptSource implements PacScriptSource {
private static final int DEFAULT_CONNECT_TIMEOUT = 1 * 1000; // seconds
private static final int DEFAULT_READ_TIMEOUT = 2 * 1000; // seconds
public static final String OVERRIDE_CONNECT_TIMEOUT = "com.btr.proxy.url.connectTimeout";
public static final String OVERRIDE_READ_TIMEOUT = "com.btr.proxy.url.readTimeout";
private final String scriptUrl;
private String scriptContent;
private long expireAtMillis;
/*************************************************************************
* Constructor
* @param url the URL to download the script from.
************************************************************************/
public UrlPacScriptSource(String url) {
super();
this.expireAtMillis = 0;
this.scriptUrl = url;
}
/*************************************************************************
* getScriptContent
* @see com.btr.proxy.selector.pac.PacScriptSource#getScriptContent()
************************************************************************/
public synchronized String getScriptContent() throws IOException {
if (this.scriptContent == null ||
(this.expireAtMillis > 0
&& this.expireAtMillis > System.currentTimeMillis())) {
try {
if (this.scriptUrl.startsWith("file:/") || this.scriptUrl.indexOf(":/") == -1) {
this.scriptContent = readPacFileContent(this.scriptUrl);
} else {
this.scriptContent = downloadPacContent(this.scriptUrl);
}
} catch (IOException e) {
Logger.log(getClass(), LogLevel.ERROR, "Loading script failed from: {0} with error {1}", this.scriptUrl, e);
this.scriptContent = "";
throw e;
}
}
return this.scriptContent;
}
/*************************************************************************
* Reads a PAC script from a local file.
* @param scriptUrl
* @return the content of the script file.
* @throws IOException
* @throws URISyntaxException
************************************************************************/
private String readPacFileContent(String scriptUrl) throws IOException {
try {
File file = null;
if (scriptUrl.indexOf(":/") == -1) {
file = new File(scriptUrl);
} else {
file = new File(new URL(scriptUrl).toURI());
}
BufferedReader r = new BufferedReader(new FileReader(file));
StringBuilder result = new StringBuilder();
try {
String line;
while ((line = r.readLine()) != null) {
result.append(line).append("\n");
}
} finally {
r.close();
}
return result.toString();
} catch (Exception e) {
Logger.log(getClass(), LogLevel.ERROR, "File reading error.", e);
throw new IOException(e.getMessage());
}
}
/*************************************************************************
* Downloads the script from a webserver.
* @param url the URL to the script file.
* @return the script content.
* @throws IOException on read error.
************************************************************************/
private String downloadPacContent(String url) throws IOException {
if (url == null) {
throw new IOException("Invalid PAC script URL: null");
}
setPacProxySelectorEnabled(false);
HttpURLConnection con = null;
try {
con = setupHTTPConnection(url);
if (con.getResponseCode() != 200) {
throw new IOException("Server returned: "+con.getResponseCode()+" "+con.getResponseMessage());
}
// Read expire date.
this.expireAtMillis = con.getExpiration();
BufferedReader r = getReader(con);
String result = readAllContent(r);
r.close();
return result;
} finally {
setPacProxySelectorEnabled(true);
if (con != null) {
con.disconnect();
}
}
}
/*************************************************************************
* Enables/disables the PAC proxy selector while we download to prevent recursion.
* See issue: 26 in the change tracker.
************************************************************************/
private void setPacProxySelectorEnabled(boolean enable) {
PacProxySelector.setEnabled(enable);
}
/*************************************************************************
* Reads the whole content available into a String.
* @param r to read from.
* @return the complete PAC file content.
* @throws IOException
************************************************************************/
private String readAllContent(BufferedReader r) throws IOException {
StringBuilder result = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
result.append(line).append("\n");
}
return result.toString();
}
/*************************************************************************
* Build a BufferedReader around the open HTTP connection.
* @param con to read from
* @return the BufferedReader.
* @throws UnsupportedEncodingException
* @throws IOException
************************************************************************/
private BufferedReader getReader(HttpURLConnection con)
throws UnsupportedEncodingException, IOException {
String charsetName = parseCharsetFromHeader(con.getContentType());
BufferedReader r = new BufferedReader(new InputStreamReader(con.getInputStream(), charsetName));
return r;
}
/*************************************************************************
* Configure the connection to download from.
* @param url to get the pac file content from
* @return a HTTPUrlConnecion to this url.
* @throws IOException
* @throws MalformedURLException
************************************************************************/
private HttpURLConnection setupHTTPConnection(String url)
throws IOException, MalformedURLException {
HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection(Proxy.NO_PROXY);
con.setConnectTimeout(getTimeOut(OVERRIDE_CONNECT_TIMEOUT, DEFAULT_CONNECT_TIMEOUT));
con.setReadTimeout(getTimeOut(OVERRIDE_READ_TIMEOUT, DEFAULT_READ_TIMEOUT));
con.setInstanceFollowRedirects(true);
con.setRequestProperty("accept", "application/x-ns-proxy-autoconfig, */*;q=0.8");
return con;
}
/*************************************************************************
* Gets the timeout value from a property or uses the given default value if
* the property cannot be parsed.
* @param overrideProperty the property to define the timeout value in milliseconds
* @param defaultValue the default timeout value in milliseconds.
* @return the value to use.
************************************************************************/
protected int getTimeOut(String overrideProperty, int defaultValue) {
int timeout = defaultValue;
String prop = System.getProperty(overrideProperty);
if (prop != null && prop.trim().length() > 0) {
try {
timeout = MiscUtil.parseInt(prop.trim());
} catch (NumberFormatException e) {
Logger.log(getClass(), LogLevel.DEBUG, "Invalid override property : {0}={1}", overrideProperty, prop);
// In this case use the default value.
}
}
return timeout;
}
/*************************************************************************
* Response Content-Type could be something like this:
* application/x-ns-proxy-autoconfig; charset=UTF-8
* @param contentType header field.
* @return the extracted charset if set else a default charset.
************************************************************************/
String parseCharsetFromHeader(String contentType) {
String result = "ISO-8859-1";
if (contentType != null) {
String[] paramList = contentType.split(";");
for (String param : paramList) {
if (param.toLowerCase().trim().startsWith("charset") && param.indexOf("=") != -1) {
result = param.substring(param.indexOf("=")+1).trim();
}
}
}
return result;
}
/***************************************************************************
* @see java.lang.Object#toString()
**************************************************************************/
@Override
public String toString() {
return this.scriptUrl;
}
/*************************************************************************
* isScriptValid
* @see com.btr.proxy.selector.pac.PacScriptSource#isScriptValid()
************************************************************************/
public boolean isScriptValid() {
try {
String script = getScriptContent();
if (script == null || script.trim().length() == 0) {
Logger.log(getClass(), LogLevel.DEBUG, "PAC script is empty. Skipping script!");
return false;
}
if (script.indexOf("FindProxyForURL") == -1) {
Logger.log(getClass(), LogLevel.DEBUG, "PAC script entry point FindProxyForURL not found. Skipping script!");
return false;
}
return true;
} catch (IOException e) {
Logger.log(getClass(), LogLevel.DEBUG, "File reading error: {0}", e);
return false;
}
}
}
