com.subgraph.vega.impl.scanner.ScanProbe.java Source code

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Here is the source code for com.subgraph.vega.impl.scanner.ScanProbe.java

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/*******************************************************************************
 * Copyright (c) 2011 Subgraph.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Subgraph - initial API and implementation
 ******************************************************************************/
package com.subgraph.vega.impl.scanner;

import java.net.URI;
import java.net.URISyntaxException;

import org.apache.http.Header;
import org.apache.http.client.methods.HttpGet;

import com.subgraph.vega.api.http.requests.IHttpRequestEngine;
import com.subgraph.vega.api.http.requests.IHttpResponse;
import com.subgraph.vega.api.http.requests.RequestEngineException;
import com.subgraph.vega.api.scanner.IScanProbeResult;

public class ScanProbe {
    private final static int MAX_REDIRECT_COUNT = 5;
    private final URI targetURI;
    private final IHttpRequestEngine requestEngine;
    private volatile HttpGet currentRequest;

    ScanProbe(URI targetURI, IHttpRequestEngine requestEngine) {
        this.targetURI = targetURI;
        this.requestEngine = requestEngine;
    }

    IScanProbeResult runProbe() {
        currentRequest = new HttpGet(targetURI);
        try {
            IHttpResponse response = requestEngine.sendRequest(currentRequest);
            return processFirstProbeResponse(targetURI, response);
        } catch (RequestEngineException e) {
            return ScanProbeResult.createConnectFailedResult(e.getMessage());
        }
    }

    private IScanProbeResult processFirstProbeResponse(URI targetURI, IHttpResponse response) {
        if (isResponseRedirect(response)) {
            return processRedirect(targetURI, response);
        }
        return ScanProbeResult.createOkResult();
    }

    private boolean isResponseRedirect(IHttpResponse response) {
        final int code = response.getResponseCode();
        return (code == 301 || code == 302 || code == 303 || code == 307);
    }

    private IScanProbeResult processRedirect(URI originalTarget, IHttpResponse response) {
        int redirectCount = 1;

        while (redirectCount < MAX_REDIRECT_COUNT) {
            URI location = getLocationURI(response);
            if (location == null) {
                final String msg = "Target address redirected to a location which could not be understood";
                return ScanProbeResult.createRedirectFailedResult(msg);
            }

            try {
                currentRequest = new HttpGet(location);
                response = requestEngine.sendRequest(currentRequest);
                if (!isResponseRedirect(response)) {
                    return ScanProbeResult.createRedirectResult(location);
                }
            } catch (RequestEngineException e) {
                return ScanProbeResult
                        .createRedirectFailedResult(createRedirectExceptionMessage(originalTarget, location, e));
            }
            redirectCount += 1;
        }
        return ScanProbeResult
                .createConnectFailedResult("Could not connect to target because maximum redirection limit reached");
    }

    private String createRedirectExceptionMessage(URI targetURI, URI location, Exception e) {
        final StringBuilder sb = new StringBuilder();
        sb.append("Target address ");
        sb.append(targetURI.toString());
        sb.append(" redirected to address ");
        sb.append(location.toString());
        sb.append(" which was not reachable");
        sb.append(e.getMessage());
        return sb.toString();
    }

    private URI getLocationURI(IHttpResponse response) {
        final Header locationHeader = response.getRawResponse().getFirstHeader("Location");
        if (locationHeader == null) {
            return null;
        }
        final String location = locationHeader.getValue();
        try {
            return new URI(location);
        } catch (URISyntaxException e) {
            return null;
        }
    }

    void abort() {
        final HttpGet get = currentRequest;
        if (get != null) {
            get.abort();
        }
    }
}