/*
    * Copyright (C) 2008-2010, Google Inc.
    * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
    * Copyright (C) 2013, Matthias Sohn <matthias.sohn@sap.com>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
   * available at http://www.eclipse.org/org/documents/edl-v10.php
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.eclipse.jgit.transport;
  
  import static org.eclipse.jgit.util.HttpSupport.ENCODING_GZIP;
  import static org.eclipse.jgit.util.HttpSupport.HDR_ACCEPT;
  import static org.eclipse.jgit.util.HttpSupport.HDR_ACCEPT_ENCODING;
  import static org.eclipse.jgit.util.HttpSupport.HDR_CONTENT_ENCODING;
  import static org.eclipse.jgit.util.HttpSupport.HDR_CONTENT_TYPE;
  import static org.eclipse.jgit.util.HttpSupport.HDR_PRAGMA;
  import static org.eclipse.jgit.util.HttpSupport.HDR_USER_AGENT;
  import static org.eclipse.jgit.util.HttpSupport.HDR_WWW_AUTHENTICATE;
  import static org.eclipse.jgit.util.HttpSupport.METHOD_GET;
  import static org.eclipse.jgit.util.HttpSupport.METHOD_POST;
  
  import java.io.BufferedReader;
  import java.io.ByteArrayInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.net.MalformedURLException;
  import java.net.Proxy;
  import java.net.ProxySelector;
  import java.net.URL;
  import java.security.KeyManagementException;
  import java.security.NoSuchAlgorithmException;
  import java.security.cert.X509Certificate;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.EnumSet;
  import java.util.LinkedHashSet;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeMap;
  import java.util.zip.GZIPInputStream;
  import java.util.zip.GZIPOutputStream;
  
  import javax.net.ssl.HostnameVerifier;
  import javax.net.ssl.SSLSession;
  import javax.net.ssl.TrustManager;
  import javax.net.ssl.X509TrustManager;
  
  import org.eclipse.jgit.errors.NoRemoteRepositoryException;
  import org.eclipse.jgit.errors.NotSupportedException;
  import org.eclipse.jgit.errors.PackProtocolException;
  import org.eclipse.jgit.errors.TransportException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.internal.storage.file.RefDirectory;
  import org.eclipse.jgit.lib.Config;
  import org.eclipse.jgit.lib.Config.SectionParser;
  import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectIdRef;
 import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.SymbolicRef;
 import org.eclipse.jgit.transport.http.HttpConnection;
 import org.eclipse.jgit.util.HttpSupport;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.RawParseUtils;
 import org.eclipse.jgit.util.TemporaryBuffer;
 import org.eclipse.jgit.util.io.DisabledOutputStream;
 import org.eclipse.jgit.util.io.UnionInputStream;
 
 /**
  * Transport over HTTP and FTP protocols.
  * <p>
  * If the transport is using HTTP and the remote HTTP service is Git-aware
  * (speaks the "smart-http protocol") this client will automatically take
  * advantage of the additional Git-specific HTTP extensions. If the remote
  * service does not support these extensions, the client will degrade to direct
  * file fetching.
  * <p>
  * If the remote (server side) repository does not have the specialized Git
  * support, object files are retrieved directly through standard HTTP GET (or
  * binary FTP GET) requests. This make it easy to serve a Git repository through
  * a standard web host provider that does not offer specific support for Git.
  *
  * @see WalkFetchConnection
  */
 public class TransportHttp extends HttpTransport implements WalkTransport,
 		PackTransport {
 
 	private static final String SVC_UPLOAD_PACK = "git-upload-pack"; //$NON-NLS-1$
 
 	private static final String SVC_RECEIVE_PACK = "git-receive-pack"; //$NON-NLS-1$
 
 	static final TransportProtocol PROTO_HTTP = new TransportProtocol() {
 		private final String[] schemeNames = { "http", "https" }; //$NON-NLS-1$ //$NON-NLS-2$
 
 		private final Set<String> schemeSet = Collections
 				.unmodifiableSet(new LinkedHashSet<String>(Arrays
 						.asList(schemeNames)));
 
 		public String getName() {
 			return JGitText.get().transportProtoHTTP;
 		}
 
 		public Set<String> getSchemes() {
 			return schemeSet;
 		}
 
 		public Set<URIishField> getRequiredFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.HOST,
 					URIishField.PATH));
 		}
 
 		public Set<URIishField> getOptionalFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.USER,
 					URIishField.PASS, URIishField.PORT));
 		}
 
 		public int getDefaultPort() {
 			return 80;
 		}
 
 		public Transport open(URIish uri, Repository local, String remoteName)
 				throws NotSupportedException {
 			return new TransportHttp(local, uri);
 		}
 
 		public Transport open(URIish uri) throws NotSupportedException {
 			return new TransportHttp(uri);
 		}
 	};
 
 	static final TransportProtocol PROTO_FTP = new TransportProtocol() {
 		public String getName() {
 			return JGitText.get().transportProtoFTP;
 		}
 
 		public Set<String> getSchemes() {
 			return Collections.singleton("ftp"); //$NON-NLS-1$
 		}
 
 		public Set<URIishField> getRequiredFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.HOST,
 					URIishField.PATH));
 		}
 
 		public Set<URIishField> getOptionalFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.USER,
 					URIishField.PASS, URIishField.PORT));
 		}
 
 		public int getDefaultPort() {
 			return 21;
 		}
 
 		public Transport open(URIish uri, Repository local, String remoteName)
 				throws NotSupportedException {
 			return new TransportHttp(local, uri);
 		}
 	};
 
 	private static final Config.SectionParser<HttpConfig> HTTP_KEY = new SectionParser<HttpConfig>() {
 		public HttpConfig parse(final Config cfg) {
 			return new HttpConfig(cfg);
 		}
 	};
 
 	private static class HttpConfig {
 		final int postBuffer;
 
 		final boolean sslVerify;
 
 		HttpConfig(final Config rc) {
 			postBuffer = rc.getInt("http", "postbuffer", 1 * 1024 * 1024); //$NON-NLS-1$  //$NON-NLS-2$
 			sslVerify = rc.getBoolean("http", "sslVerify", true); //$NON-NLS-1$ //$NON-NLS-2$
 		}
 
 		private HttpConfig() {
 			this(new Config());
 		}
 	}
 
 	private final URL baseUrl;
 
 	private final URL objectsUrl;
 
 	private final HttpConfig http;
 
 	private final ProxySelector proxySelector;
 
 	private boolean useSmartHttp = true;
 
 	private HttpAuthMethod authMethod = HttpAuthMethod.Type.NONE.method(null);
 
 	private Map<String, String> headers;
 
 	TransportHttp(final Repository local, final URIish uri)
 			throws NotSupportedException {
 		super(local, uri);
 		try {
 			String uriString = uri.toString();
 			if (!uriString.endsWith("/")) //$NON-NLS-1$
 				uriString += "/"; //$NON-NLS-1$
 			baseUrl = new URL(uriString);
 			objectsUrl = new URL(baseUrl, "objects/"); //$NON-NLS-1$
 		} catch (MalformedURLException e) {
 			throw new NotSupportedException(MessageFormat.format(JGitText.get().invalidURL, uri), e);
 		}
 		http = local.getConfig().get(HTTP_KEY);
 		proxySelector = ProxySelector.getDefault();
 	}
 
 	/**
 	 * Create a minimal HTTP transport with default configuration values.
 	 *
 	 * @param uri
 	 * @throws NotSupportedException
 	 */
 	TransportHttp(final URIish uri) throws NotSupportedException {
 		super(uri);
 		try {
 			String uriString = uri.toString();
 			if (!uriString.endsWith("/")) //$NON-NLS-1$
 				uriString += "/"; //$NON-NLS-1$
 			baseUrl = new URL(uriString);
 			objectsUrl = new URL(baseUrl, "objects/"); //$NON-NLS-1$
 		} catch (MalformedURLException e) {
 			throw new NotSupportedException(MessageFormat.format(JGitText.get().invalidURL, uri), e);
 		}
 		http = new HttpConfig();
 		proxySelector = ProxySelector.getDefault();
 	}
 
 	/**
 	 * Toggle whether or not smart HTTP transport should be used.
 	 * <p>
 	 * This flag exists primarily to support backwards compatibility testing
 	 * within a testing framework, there is no need to modify it in most
 	 * applications.
 	 *
 	 * @param on
 	 *            if {@code true} (default), smart HTTP is enabled.
 	 */
 	public void setUseSmartHttp(final boolean on) {
 		useSmartHttp = on;
 	}
 
 	@Override
 	public FetchConnection openFetch() throws TransportException,
 			NotSupportedException {
 		final String service = SVC_UPLOAD_PACK;
 		try {
 			final HttpConnection c = connect(service);
 			final InputStream in = openInputStream(c);
 			try {
 				BaseConnection f;
 				if (isSmartHttp(c, service)) {
 					readSmartHeaders(in, service);
 					f = new SmartHttpFetchConnection(in);
 				} else {
 					// Assume this server doesn't support smart HTTP fetch
 					// and fall back on dumb object walking.
 					f = newDumbConnection(in);
 				}
 				f.setPeerUserAgent(c.getHeaderField(HttpSupport.HDR_SERVER));
 				return (FetchConnection) f;
 			} finally {
 				in.close();
 			}
 		} catch (NotSupportedException err) {
 			throw err;
 		} catch (TransportException err) {
 			throw err;
 		} catch (IOException err) {
 			throw new TransportException(uri, JGitText.get().errorReadingInfoRefs, err);
 		}
 	}
 
 	private WalkFetchConnection newDumbConnection(InputStream in)
 			throws IOException, PackProtocolException {
 		HttpObjectDB d = new HttpObjectDB(objectsUrl);
 		BufferedReader br = toBufferedReader(in);
 		Map<String, Ref> refs;
 		try {
 			refs = d.readAdvertisedImpl(br);
 		} finally {
 			br.close();
 		}
 
 		if (!refs.containsKey(Constants.HEAD)) {
 			// If HEAD was not published in the info/refs file (it usually
 			// is not there) download HEAD by itself as a loose file and do
 			// the resolution by hand.
 			//
 			HttpConnection conn = httpOpen(new URL(baseUrl, Constants.HEAD));
 			int status = HttpSupport.response(conn);
 			switch (status) {
 			case HttpConnection.HTTP_OK: {
 				br = toBufferedReader(openInputStream(conn));
 				try {
 					String line = br.readLine();
 					if (line != null && line.startsWith(RefDirectory.SYMREF)) {
 						String target = line.substring(RefDirectory.SYMREF.length());
 						Ref r = refs.get(target);
 						if (r == null)
 							r = new ObjectIdRef.Unpeeled(Ref.Storage.NEW, target, null);
 						r = new SymbolicRef(Constants.HEAD, r);
 						refs.put(r.getName(), r);
 					} else if (line != null && ObjectId.isId(line)) {
 						Ref r = new ObjectIdRef.Unpeeled(Ref.Storage.NETWORK,
 								Constants.HEAD, ObjectId.fromString(line));
 						refs.put(r.getName(), r);
 					}
 				} finally {
 					br.close();
 				}
 				break;
 			}
 
 			case HttpConnection.HTTP_NOT_FOUND:
 				break;
 
 			default:
 				throw new TransportException(uri, MessageFormat.format(
 						JGitText.get().cannotReadHEAD, Integer.valueOf(status),
 						conn.getResponseMessage()));
 			}
 		}
 
 		WalkFetchConnection wfc = new WalkFetchConnection(this, d);
 		wfc.available(refs);
 		return wfc;
 	}
 
 	private BufferedReader toBufferedReader(InputStream in) {
 		return new BufferedReader(new InputStreamReader(in, Constants.CHARSET));
 	}
 
 	@Override
 	public PushConnection openPush() throws NotSupportedException,
 			TransportException {
 		final String service = SVC_RECEIVE_PACK;
 		try {
 			final HttpConnection c = connect(service);
 			final InputStream in = openInputStream(c);
 			try {
 				if (isSmartHttp(c, service)) {
 					return smartPush(service, c, in);
 				} else if (!useSmartHttp) {
 					final String msg = JGitText.get().smartHTTPPushDisabled;
 					throw new NotSupportedException(msg);
 
 				} else {
 					final String msg = JGitText.get().remoteDoesNotSupportSmartHTTPPush;
 					throw new NotSupportedException(msg);
 				}
 			} finally {
 				in.close();
 			}
 		} catch (NotSupportedException err) {
 			throw err;
 		} catch (TransportException err) {
 			throw err;
 		} catch (IOException err) {
 			throw new TransportException(uri, JGitText.get().errorReadingInfoRefs, err);
 		}
 	}
 
 	private PushConnection smartPush(String service, HttpConnection c,
 			InputStream in) throws IOException, TransportException {
 		readSmartHeaders(in, service);
 		SmartHttpPushConnection p = new SmartHttpPushConnection(in);
 		p.setPeerUserAgent(c.getHeaderField(HttpSupport.HDR_SERVER));
 		return p;
 	}
 
 	@Override
 	public void close() {
 		// No explicit connections are maintained.
 	}
 
 	/**
 	 * Set additional headers on the HTTP connection
 	 *
 	 * @param headers
 	 *            a map of name:values that are to be set as headers on the HTTP
 	 *            connection
 	 * @since 3.4
 	 */
 	public void setAdditionalHeaders(Map<String, String> headers) {
 		this.headers = headers;
 	}
 
 	private HttpConnection connect(final String service)
 			throws TransportException, NotSupportedException {
 		final URL u;
 		try {
 			final StringBuilder b = new StringBuilder();
 			b.append(baseUrl);
 
 			if (b.charAt(b.length() - 1) != '/')
 				b.append('/');
 			b.append(Constants.INFO_REFS);
 
 			if (useSmartHttp) {
 				b.append(b.indexOf("?") < 0 ? '?' : '&'); //$NON-NLS-1$
 				b.append("service="); //$NON-NLS-1$
 				b.append(service);
 			}
 
 			u = new URL(b.toString());
 		} catch (MalformedURLException e) {
 			throw new NotSupportedException(MessageFormat.format(JGitText.get().invalidURL, uri), e);
 		}
 
 		try {
 			int authAttempts = 1;
 			for (;;) {
 				final HttpConnection conn = httpOpen(u);
 				if (useSmartHttp) {
 					String exp = "application/x-" + service + "-advertisement"; //$NON-NLS-1$ //$NON-NLS-2$
 					conn.setRequestProperty(HDR_ACCEPT, exp + ", */*"); //$NON-NLS-1$
 				} else {
 					conn.setRequestProperty(HDR_ACCEPT, "*/*"); //$NON-NLS-1$
 				}
 				final int status = HttpSupport.response(conn);
 				switch (status) {
 				case HttpConnection.HTTP_OK:
 					// Check if HttpConnection did some authentication in the
 					// background (e.g Kerberos/SPNEGO).
 					// That may not work for streaming requests and jgit
 					// explicit authentication would be required
 					if (authMethod.getType() == HttpAuthMethod.Type.NONE
 							&& conn.getHeaderField(HDR_WWW_AUTHENTICATE) != null)
 						authMethod = HttpAuthMethod.scanResponse(conn);
 					return conn;
 
 				case HttpConnection.HTTP_NOT_FOUND:
 					throw new NoRemoteRepositoryException(uri,
 							MessageFormat.format(JGitText.get().uriNotFound, u));
 
 				case HttpConnection.HTTP_UNAUTHORIZED:
 					authMethod = HttpAuthMethod.scanResponse(conn);
 					if (authMethod.getType() == HttpAuthMethod.Type.NONE)
 						throw new TransportException(uri, MessageFormat.format(
 								JGitText.get().authenticationNotSupported, uri));
 					CredentialsProvider credentialsProvider = getCredentialsProvider();
 					if (credentialsProvider == null)
 						throw new TransportException(uri,
 								JGitText.get().noCredentialsProvider);
 					if (authAttempts > 1)
 						credentialsProvider.reset(uri);
 					if (3 < authAttempts
 							|| !authMethod.authorize(uri, credentialsProvider)) {
 						throw new TransportException(uri,
 								JGitText.get().notAuthorized);
 					}
 					authAttempts++;
 					continue;
 
 				case HttpConnection.HTTP_FORBIDDEN:
 					throw new TransportException(uri, MessageFormat.format(
 							JGitText.get().serviceNotPermitted, service));
 
 				default:
 					String err = status + " " + conn.getResponseMessage(); //$NON-NLS-1$
 					throw new TransportException(uri, err);
 				}
 			}
 		} catch (NotSupportedException e) {
 			throw e;
 		} catch (TransportException e) {
 			throw e;
 		} catch (IOException e) {
 			throw new TransportException(uri, MessageFormat.format(JGitText.get().cannotOpenService, service), e);
 		}
 	}
 
 	final HttpConnection httpOpen(URL u) throws IOException {
 		return httpOpen(METHOD_GET, u);
 	}
 
 	/**
 	 * Open an HTTP connection.
 	 *
 	 * @param method
 	 * @param u
 	 * @return the connection
 	 * @throws IOException
 	 * @since 3.3
 	 */
 	protected HttpConnection httpOpen(String method, URL u)
 			throws IOException {
 		final Proxy proxy = HttpSupport.proxyFor(proxySelector, u);
 		HttpConnection conn = connectionFactory.create(u, proxy);
 
 		if (!http.sslVerify && "https".equals(u.getProtocol())) { //$NON-NLS-1$
 			disableSslVerify(conn);
 		}
 
 		conn.setRequestMethod(method);
 		conn.setUseCaches(false);
 		conn.setRequestProperty(HDR_ACCEPT_ENCODING, ENCODING_GZIP);
 		conn.setRequestProperty(HDR_PRAGMA, "no-cache"); //$NON-NLS-1$
 		if (UserAgent.get() != null) {
 			conn.setRequestProperty(HDR_USER_AGENT, UserAgent.get());
 		}
 		int timeOut = getTimeout();
 		if (timeOut != -1) {
 			int effTimeOut = timeOut * 1000;
 			conn.setConnectTimeout(effTimeOut);
 			conn.setReadTimeout(effTimeOut);
 		}
 		if (this.headers != null && !this.headers.isEmpty()) {
 			for (Map.Entry<String, String> entry : this.headers.entrySet())
 				conn.setRequestProperty(entry.getKey(), entry.getValue());
 		}
 		authMethod.configureRequest(conn);
 		return conn;
 	}
 
 	private void disableSslVerify(HttpConnection conn)
 			throws IOException {
 		final TrustManager[] trustAllCerts = new TrustManager[] { new DummyX509TrustManager() };
 		try {
 			conn.configure(null, trustAllCerts, null);
 			conn.setHostnameVerifier(new DummyHostnameVerifier());
 		} catch (KeyManagementException e) {
 			throw new IOException(e.getMessage());
 		} catch (NoSuchAlgorithmException e) {
 			throw new IOException(e.getMessage());
 		}
 	}
 
 	final InputStream openInputStream(HttpConnection conn)
 			throws IOException {
 		InputStream input = conn.getInputStream();
 		if (ENCODING_GZIP.equals(conn.getHeaderField(HDR_CONTENT_ENCODING)))
 			input = new GZIPInputStream(input);
 		return input;
 	}
 
 	IOException wrongContentType(String expType, String actType) {
 		final String why = MessageFormat.format(JGitText.get().expectedReceivedContentType, expType, actType);
 		return new TransportException(uri, why);
 	}
 
 	private boolean isSmartHttp(final HttpConnection c, final String service) {
 		final String expType = "application/x-" + service + "-advertisement"; //$NON-NLS-1$ //$NON-NLS-2$
 		final String actType = c.getContentType();
 		return expType.equals(actType);
 	}
 
 	private void readSmartHeaders(final InputStream in, final String service)
 			throws IOException {
 		// A smart reply will have a '#' after the first 4 bytes, but
 		// a dumb reply cannot contain a '#' until after byte 41. Do a
 		// quick check to make sure its a smart reply before we parse
 		// as a pkt-line stream.
 		//
 		final byte[] magic = new byte[5];
 		IO.readFully(in, magic, 0, magic.length);
 		if (magic[4] != '#') {
 			throw new TransportException(uri, MessageFormat.format(
 					JGitText.get().expectedPktLineWithService, RawParseUtils.decode(magic)));
 		}
 
 		final PacketLineIn pckIn = new PacketLineIn(new UnionInputStream(
 				new ByteArrayInputStream(magic), in));
 		final String exp = "# service=" + service; //$NON-NLS-1$
 		final String act = pckIn.readString();
 		if (!exp.equals(act)) {
 			throw new TransportException(uri, MessageFormat.format(
 					JGitText.get().expectedGot, exp, act));
 		}
 
 		while (pckIn.readString() != PacketLineIn.END) {
 			// for now, ignore the remaining header lines
 		}
 	}
 
 	class HttpObjectDB extends WalkRemoteObjectDatabase {
 		private final URL httpObjectsUrl;
 
 		HttpObjectDB(final URL b) {
 			httpObjectsUrl = b;
 		}
 
 		@Override
 		URIish getURI() {
 			return new URIish(httpObjectsUrl);
 		}
 
 		@Override
 		Collection<WalkRemoteObjectDatabase> getAlternates() throws IOException {
 			try {
 				return readAlternates(INFO_HTTP_ALTERNATES);
 			} catch (FileNotFoundException err) {
 				// Fall through.
 			}
 
 			try {
 				return readAlternates(INFO_ALTERNATES);
 			} catch (FileNotFoundException err) {
 				// Fall through.
 			}
 
 			return null;
 		}
 
 		@Override
 		WalkRemoteObjectDatabase openAlternate(final String location)
 				throws IOException {
 			return new HttpObjectDB(new URL(httpObjectsUrl, location));
 		}
 
 		@Override
 		Collection<String> getPackNames() throws IOException {
 			final Collection<String> packs = new ArrayList<String>();
 			try {
 				final BufferedReader br = openReader(INFO_PACKS);
 				try {
 					for (;;) {
 						final String s = br.readLine();
 						if (s == null || s.length() == 0)
 							break;
 						if (!s.startsWith("P pack-") || !s.endsWith(".pack")) //$NON-NLS-1$ //$NON-NLS-2$
 							throw invalidAdvertisement(s);
 						packs.add(s.substring(2));
 					}
 					return packs;
 				} finally {
 					br.close();
 				}
 			} catch (FileNotFoundException err) {
 				return packs;
 			}
 		}
 
 		@Override
 		FileStream open(final String path) throws IOException {
 			final URL base = httpObjectsUrl;
 			final URL u = new URL(base, path);
 			final HttpConnection c = httpOpen(u);
 			switch (HttpSupport.response(c)) {
 			case HttpConnection.HTTP_OK:
 				final InputStream in = openInputStream(c);
 				final int len = c.getContentLength();
 				return new FileStream(in, len);
 			case HttpConnection.HTTP_NOT_FOUND:
 				throw new FileNotFoundException(u.toString());
 			default:
 				throw new IOException(u.toString() + ": " //$NON-NLS-1$
 						+ HttpSupport.response(c) + " " //$NON-NLS-1$
 						+ c.getResponseMessage());
 			}
 		}
 
 		Map<String, Ref> readAdvertisedImpl(final BufferedReader br)
 				throws IOException, PackProtocolException {
 			final TreeMap<String, Ref> avail = new TreeMap<String, Ref>();
 			for (;;) {
 				String line = br.readLine();
 				if (line == null)
 					break;
 
 				final int tab = line.indexOf('\t');
 				if (tab < 0)
 					throw invalidAdvertisement(line);
 
 				String name;
 				final ObjectId id;
 
 				name = line.substring(tab + 1);
 				id = ObjectId.fromString(line.substring(0, tab));
 				if (name.endsWith("^{}")) { //$NON-NLS-1$
 					name = name.substring(0, name.length() - 3);
 					final Ref prior = avail.get(name);
 					if (prior == null)
 						throw outOfOrderAdvertisement(name);
 
 					if (prior.getPeeledObjectId() != null)
 						throw duplicateAdvertisement(name + "^{}"); //$NON-NLS-1$
 
 					avail.put(name, new ObjectIdRef.PeeledTag(
 							Ref.Storage.NETWORK, name,
 							prior.getObjectId(), id));
 				} else {
 					Ref prior = avail.put(name, new ObjectIdRef.PeeledNonTag(
 							Ref.Storage.NETWORK, name, id));
 					if (prior != null)
 						throw duplicateAdvertisement(name);
 				}
 			}
 			return avail;
 		}
 
 		private PackProtocolException outOfOrderAdvertisement(final String n) {
 			return new PackProtocolException(MessageFormat.format(JGitText.get().advertisementOfCameBefore, n, n));
 		}
 
 		private PackProtocolException invalidAdvertisement(final String n) {
 			return new PackProtocolException(MessageFormat.format(JGitText.get().invalidAdvertisementOf, n));
 		}
 
 		private PackProtocolException duplicateAdvertisement(final String n) {
 			return new PackProtocolException(MessageFormat.format(JGitText.get().duplicateAdvertisementsOf, n));
 		}
 
 		@Override
 		void close() {
 			// We do not maintain persistent connections.
 		}
 	}
 
 	class SmartHttpFetchConnection extends BasePackFetchConnection {
 		private MultiRequestService svc;
 
 		SmartHttpFetchConnection(final InputStream advertisement)
 				throws TransportException {
 			super(TransportHttp.this);
 			statelessRPC = true;
 
 			init(advertisement, DisabledOutputStream.INSTANCE);
 			outNeedsEnd = false;
 			readAdvertisedRefs();
 		}
 
 		@Override
 		protected void doFetch(final ProgressMonitor monitor,
 				final Collection<Ref> want, final Set<ObjectId> have,
 				final OutputStream outputStream) throws TransportException {
 			try {
 				svc = new MultiRequestService(SVC_UPLOAD_PACK);
 				init(svc.getInputStream(), svc.getOutputStream());
 				super.doFetch(monitor, want, have, outputStream);
 			} finally {
 				svc = null;
 			}
 		}
 
 		@Override
 		protected void onReceivePack() {
 			svc.finalRequest = true;
 		}
 	}
 
 	class SmartHttpPushConnection extends BasePackPushConnection {
 		SmartHttpPushConnection(final InputStream advertisement)
 				throws TransportException {
 			super(TransportHttp.this);
 			statelessRPC = true;
 
 			init(advertisement, DisabledOutputStream.INSTANCE);
 			outNeedsEnd = false;
 			readAdvertisedRefs();
 		}
 
 		protected void doPush(final ProgressMonitor monitor,
 				final Map<String, RemoteRefUpdate> refUpdates,
 				OutputStream outputStream) throws TransportException {
 			final Service svc = new MultiRequestService(SVC_RECEIVE_PACK);
 			init(svc.getInputStream(), svc.getOutputStream());
 			super.doPush(monitor, refUpdates, outputStream);
 		}
 	}
 
 	/** Basic service for sending and receiving HTTP requests. */
 	abstract class Service {
 		protected final String serviceName;
 
 		protected final String requestType;
 
 		protected final String responseType;
 
 		protected HttpConnection conn;
 
 		protected HttpOutputStream out;
 
 		protected final HttpExecuteStream execute;
 
 		final UnionInputStream in;
 
 		Service(String serviceName) {
 			this.serviceName = serviceName;
 			this.requestType = "application/x-" + serviceName + "-request"; //$NON-NLS-1$ //$NON-NLS-2$
 			this.responseType = "application/x-" + serviceName + "-result"; //$NON-NLS-1$ //$NON-NLS-2$
 
 			this.out = new HttpOutputStream();
 			this.execute = new HttpExecuteStream();
 			this.in = new UnionInputStream(execute);
 		}
 
 		void openStream() throws IOException {
 			conn = httpOpen(METHOD_POST, new URL(baseUrl, serviceName));
 			conn.setInstanceFollowRedirects(false);
 			conn.setDoOutput(true);
 			conn.setRequestProperty(HDR_CONTENT_TYPE, requestType);
 			conn.setRequestProperty(HDR_ACCEPT, responseType);
 		}
 
 		void sendRequest() throws IOException {
 			// Try to compress the content, but only if that is smaller.
 			TemporaryBuffer buf = new TemporaryBuffer.Heap(http.postBuffer);
 			try {
 				GZIPOutputStream gzip = new GZIPOutputStream(buf);
 				out.writeTo(gzip, null);
 				gzip.close();
 				if (out.length() < buf.length())
 					buf = out;
 			} catch (IOException err) {
 				// Most likely caused by overflowing the buffer, meaning
 				// its larger if it were compressed. Don't compress.
 				buf = out;
 			}
 
 			openStream();
 			if (buf != out)
 				conn.setRequestProperty(HDR_CONTENT_ENCODING, ENCODING_GZIP);
 			conn.setFixedLengthStreamingMode((int) buf.length());
 			final OutputStream httpOut = conn.getOutputStream();
 			try {
 				buf.writeTo(httpOut, null);
 			} finally {
 				httpOut.close();
 			}
 		}
 
 		void openResponse() throws IOException {
 			final int status = HttpSupport.response(conn);
 			if (status != HttpConnection.HTTP_OK) {
 				throw new TransportException(uri, status + " " //$NON-NLS-1$
 						+ conn.getResponseMessage());
 			}
 
 			final String contentType = conn.getContentType();
 			if (!responseType.equals(contentType)) {
 				conn.getInputStream().close();
 				throw wrongContentType(responseType, contentType);
 			}
 		}
 
 		HttpOutputStream getOutputStream() {
 			return out;
 		}
 
 		InputStream getInputStream() {
 			return in;
 		}
 
 		abstract void execute() throws IOException;
 
 		class HttpExecuteStream extends InputStream {
 			public int read() throws IOException {
 				execute();
 				return -1;
 			}
 
 			public int read(byte[] b, int off, int len) throws IOException {
 				execute();
 				return -1;
 			}
 
 			public long skip(long n) throws IOException {
 				execute();
 				return 0;
 			}
 		}
 
 		class HttpOutputStream extends TemporaryBuffer {
 			HttpOutputStream() {
 				super(http.postBuffer);
 			}
 
 			@Override
 			protected OutputStream overflow() throws IOException {
 				openStream();
 				conn.setChunkedStreamingMode(0);
 				return conn.getOutputStream();
 			}
 		}
 	}
 
 	/**
 	 * State required to speak multiple HTTP requests with the remote.
 	 * <p>
 	 * A service wrapper provides a normal looking InputStream and OutputStream
 	 * pair which are connected via HTTP to the named remote service. Writing to
 	 * the OutputStream is buffered until either the buffer overflows, or
 	 * reading from the InputStream occurs. If overflow occurs HTTP/1.1 and its
 	 * chunked transfer encoding is used to stream the request data to the
 	 * remote service. If the entire request fits in the memory buffer, the
 	 * older HTTP/1.0 standard and a fixed content length is used instead.
 	 * <p>
 	 * It is an error to attempt to read without there being outstanding data
 	 * ready for transmission on the OutputStream.
 	 * <p>
 	 * No state is preserved between write-read request pairs. The caller is
 	 * responsible for replaying state vector information as part of the request
 	 * data written to the OutputStream. Any session HTTP cookies may or may not
 	 * be preserved between requests, it is left up to the JVM's implementation
 	 * of the HTTP client.
 	 */
 	class MultiRequestService extends Service {
 		boolean finalRequest;
 
 		MultiRequestService(final String serviceName) {
 			super(serviceName);
 		}
 
 		/** Keep opening send-receive pairs to the given URI. */
 		@Override
 		void execute() throws IOException {
 			out.close();
 
 			if (conn == null) {
 				if (out.length() == 0) {
 					// Request output hasn't started yet, but more data is being
 					// requested. If there is no request data buffered and the
 					// final request was already sent, do nothing to ensure the
 					// caller is shown EOF on the InputStream; otherwise an
 					// programming error has occurred within this module.
 					if (finalRequest)
 						return;
 					throw new TransportException(uri,
 							JGitText.get().startingReadStageWithoutWrittenRequestDataPendingIsNotSupported);
 				}
 
 				sendRequest();
 			}
 
 			out.reset();
 
 			openResponse();
 
 			in.add(openInputStream(conn));
 			if (!finalRequest)
 				in.add(execute);
 			conn = null;
 		}
 	}
 
 	/** Service for maintaining a single long-poll connection. */
 	class LongPollService extends Service {
 		/**
 		 * @param serviceName
 		 */
 		LongPollService(String serviceName) {
 			super(serviceName);
 		}
 
 		/** Only open one send-receive request. */
 		@Override
 		void execute() throws IOException {
 			out.close();
 			if (conn == null)
 				sendRequest();
 			openResponse();
 			in.add(openInputStream(conn));
 		}
 	}
 
 	private static class DummyX509TrustManager implements X509TrustManager {
 		public X509Certificate[] getAcceptedIssuers() {
 			return null;
 		}
 
 		public void checkClientTrusted(X509Certificate[] certs, String authType) {
 			// no check
 		}
 
 		public void checkServerTrusted(X509Certificate[] certs, String authType) {
 			// no check
 		}
 	}
 
 	private static class DummyHostnameVerifier implements HostnameVerifier {
 		public boolean verify(String hostname, SSLSession session) {
 			// always accept
 			return true;
 		}
 	}
 }