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package com.btr.proxy.selector.pac;
import java.lang.reflect.Method;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import com.btr.proxy.util.Logger;
import com.btr.proxy.util.Logger.LogLevel;
/*****************************************************************************
* PAC parser using the Rhino JavaScript engine bundled with Java 1.6<br/>
* If you need PAC support with Java 1.5 then you should have a look at
* RhinoPacScriptParser.
*
* More information about PAC can be found there:<br/>
* <a href="http://en.wikipedia.org/wiki/Proxy_auto-config">Proxy_auto-config</a><br/>
* <a href="http://homepages.tesco.net/~J.deBoynePollard/FGA/web-browser-auto-proxy-configuration.html">web-browser-auto-proxy-configuration</a>
* </p>
* @author Bernd Rosstauscher (proxyvole@rosstauscher.de) Copyright 2009
****************************************************************************/
public class JavaxPacScriptParser implements PacScriptParser {
static final String SCRIPT_METHODS_OBJECT = "__pacutil";
private final PacScriptSource source;
private final ScriptEngine engine;
/*************************************************************************
* Constructor
*
* @param source
* the source for the PAC script.
* @throws ProxyEvaluationException
* on error.
************************************************************************/
public JavaxPacScriptParser(PacScriptSource source)
throws ProxyEvaluationException {
this.source = source;
this.engine = setupEngine();
}
/*************************************************************************
* Initializes the JavaScript engine and adds aliases for the functions
* defined in ScriptMethods.
*
* @throws ProxyEvaluationException
* on error.
************************************************************************/
private ScriptEngine setupEngine() throws ProxyEvaluationException {
ScriptEngineManager mng = new ScriptEngineManager();
ScriptEngine engine = mng.getEngineByMimeType("text/javascript");
engine.put(SCRIPT_METHODS_OBJECT, new PacScriptMethods());
Class<?> scriptMethodsClazz = ScriptMethods.class;
Method[] scriptMethods = scriptMethodsClazz.getMethods();
for (Method method : scriptMethods) {
String name = method.getName();
int args = method.getParameterTypes().length;
StringBuilder toEval = new StringBuilder(name).append(" = function(");
for (int i = 0; i < args; i++) {
if (i > 0) {
toEval.append(",");
}
toEval.append("arg").append(i);
}
toEval.append(") {return ");
String functionCall = buildFunctionCallCode(name, args);
// If return type is java.lang.String convert it to a JS string
if (String.class.isAssignableFrom(method.getReturnType())) {
functionCall = "String("+functionCall+")";
}
toEval.append(functionCall).append("; }");
try {
engine.eval(toEval.toString());
} catch (ScriptException e) {
Logger.log(getClass(), LogLevel.ERROR,
"JS evaluation error when creating alias for " + name + ".", e);
throw new ProxyEvaluationException(
"Error setting up script engine", e);
}
}
return engine;
}
/*************************************************************************
* Builds a JavaScript code snippet to call a function that we bind.
* @param functionName of the bound function
* @param args of the bound function
* @return the JS code to invoke the method.
************************************************************************/
private String buildFunctionCallCode(String functionName, int args) {
StringBuilder functionCall = new StringBuilder();
functionCall.append(SCRIPT_METHODS_OBJECT)
.append(".").append(functionName).append("(");
for (int i = 0; i < args; i++) {
if (i > 0) {
functionCall.append(",");
}
functionCall.append("arg").append(i);
}
functionCall.append(")");
return functionCall.toString();
}
/***************************************************************************
* Gets the source of the PAC script used by this parser.
*
* @return a PacScriptSource.
**************************************************************************/
public PacScriptSource getScriptSource() {
return this.source;
}
/*************************************************************************
* Evaluates the given URL and host against the PAC script.
*
* @param url
* the URL to evaluate.
* @param host
* the host name part of the URL.
* @return the script result.
* @throws ProxyEvaluationException
* on execution error.
************************************************************************/
public String evaluate(String url, String host)
throws ProxyEvaluationException {
try {
StringBuilder script = new StringBuilder(
this.source.getScriptContent());
String evalMethod = " ;FindProxyForURL (\"" + url + "\",\"" + host + "\")";
script.append(evalMethod);
Object result = this.engine.eval(script.toString());
return (String) result;
} catch (Exception e) {
Logger.log(getClass(), LogLevel.ERROR, "JS evaluation error.", e);
throw new ProxyEvaluationException(
"Error while executing PAC script: " + e.getMessage(), e);
}
}
}
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