com.granita.icloudcalsync.webdav.DavRedirectStrategy.java Source code

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Here is the source code for com.granita.icloudcalsync.webdav.DavRedirectStrategy.java

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/*
 * Copyright  2013  2015 Ricki Hirner (bitfire web engineering).
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/gpl.html
 */
package com.granita.icloudcalsync.webdav;

import android.util.Log;

import org.apache.http.Header;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.ProtocolException;
import org.apache.http.RequestLine;
import org.apache.http.client.RedirectStrategy;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.methods.RequestBuilder;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.protocol.HttpContext;

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

import com.granita.icloudcalsync.URIUtils;

/**
 * Custom Redirect Strategy that handles 30x for CalDAV/CardDAV-specific requests correctly
 */
public class DavRedirectStrategy implements RedirectStrategy {
    private final static String TAG = "davdroid.DavRedirectStrategy";
    public final static DavRedirectStrategy INSTANCE = new DavRedirectStrategy();

    protected final static String REDIRECTABLE_METHODS[] = { "OPTIONS", "GET", "PUT", "DELETE" };

    @Override
    public HttpUriRequest getRedirect(HttpRequest request, HttpResponse response, HttpContext context)
            throws ProtocolException {
        RequestLine line = request.getRequestLine();

        String location = getLocation(request, response, context).toString();
        Log.i(TAG, "Following redirection: " + line.getMethod() + " " + line.getUri() + " -> " + location);

        return RequestBuilder.copy(request).setUri(location).removeHeaders("Content-Length") // Content-Length will be set again automatically, if required;
                // remove it now to avoid duplicate header
                .build();
    }

    /**
     * Determines whether a response indicates a redirection and if it does, whether to follow this redirection.
     * PROPFIND and REPORT must handle redirections explicitely because multi-status processing requires knowledge of the content location.
     * @return true for 3xx responses on OPTIONS, GET, PUT, DELETE requests that have a valid Location header; false otherwise
     */
    @Override
    public boolean isRedirected(HttpRequest request, HttpResponse response, HttpContext context)
            throws ProtocolException {
        if (response.getStatusLine().getStatusCode() / 100 == 3) {
            boolean redirectable = false;
            for (String method : REDIRECTABLE_METHODS)
                if (method.equalsIgnoreCase(request.getRequestLine().getMethod())) {
                    redirectable = true;
                    break;
                }
            return redirectable && getLocation(request, response, context) != null;
        }
        return false;
    }

    /**
     * Gets the destination of a redirection 
     * @return absolute URL of new location; null if not available
     */
    static URI getLocation(HttpRequest request, HttpResponse response, HttpContext context) {
        Header locationHdr = response.getFirstHeader("Location");
        if (locationHdr == null) {
            Log.e(TAG, "Received redirection without Location header, ignoring");
            return null;
        }
        try {
            URI location = URIUtils.parseURI(locationHdr.getValue(), false);

            // some servers don't return absolute URLs as required by RFC 2616
            if (!location.isAbsolute()) {
                Log.w(TAG, "Received invalid redirection to relative URL, repairing");
                URI originalURI = URIUtils.parseURI(request.getRequestLine().getUri(), false);
                if (!originalURI.isAbsolute()) {
                    final HttpHost target = HttpClientContext.adapt(context).getTargetHost();
                    if (target != null)
                        originalURI = org.apache.http.client.utils.URIUtilsHC4.rewriteURI(originalURI, target);
                    else
                        return null;
                }
                return originalURI.resolve(location);
            }
            return location;
        } catch (URISyntaxException e) {
            Log.e(TAG, "Received redirection from/to invalid URI, ignoring", e);
        }
        return null;
    }

}