jgit/org.eclipse.jgit/src/org/eclipse/jgit/transport/ProtocolV2Parser.java

/*
 * Copyright (C) 2018, Google LLC.
 * 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;
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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package org.eclipse.jgit.transport;

import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_DEEPEN_RELATIVE;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_FILTER;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_AGENT;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_INCLUDE_TAG;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_NO_PROGRESS;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_OFS_DELTA;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SERVER_OPTION;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDE_BAND_64K;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_THIN_PACK;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_WANT_REF;

import java.io.IOException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

import org.eclipse.jgit.errors.PackProtocolException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.ObjectId;

/**
 * Parse the incoming git protocol lines from the wire and translate them into a
 * Request object.
 *
 * It requires a transferConfig object to know what the server supports (e.g.
 * ref-in-want and/or filters).
 */
final class ProtocolV2Parser {

	private final TransferConfig transferConfig;

	ProtocolV2Parser(TransferConfig transferConfig) {
		this.transferConfig = transferConfig;
	}

	/*
	 * Read lines until DELIM or END, calling the appropiate consumer.
	 *
	 * Returns the last read line (so caller can check if there is more to read
	 * in the line).
	 */
	private static String consumeCapabilities(PacketLineIn pckIn,
			Consumer<String> serverOptionConsumer,
			Consumer<String> agentConsumer) throws IOException {

		String serverOptionPrefix = OPTION_SERVER_OPTION + '=';
		String agentPrefix = OPTION_AGENT + '=';

		String line = pckIn.readString();
		while (line != PacketLineIn.DELIM && line != PacketLineIn.END) {
			if (line.startsWith(serverOptionPrefix)) {
				serverOptionConsumer
						.accept(line.substring(serverOptionPrefix.length()));
			} else if (line.startsWith(agentPrefix)) {
				agentConsumer.accept(line.substring(agentPrefix.length()));
			} else {
				// Unrecognized capability. Ignore it.
			}
			line = pckIn.readString();
		}

		return line;
	}

	/**
	 * Parse the incoming fetch request arguments from the wire. The caller must
	 * be sure that what is comings is a fetch request before coming here.
	 *
	 * @param pckIn
	 *            incoming lines
	 * @return A FetchV2Request populated with information received from the
	 *         wire.
	 * @throws PackProtocolException
	 *             incompatible options, wrong type of arguments or other issues
	 *             where the request breaks the protocol.
	 * @throws IOException
	 *             an IO error prevented reading the incoming message.
	 */
	FetchV2Request parseFetchRequest(PacketLineIn pckIn)
			throws PackProtocolException, IOException {
		FetchV2Request.Builder reqBuilder = FetchV2Request.builder();

		// Packs are always sent multiplexed and using full 64K
		// lengths.
		reqBuilder.addClientCapability(OPTION_SIDE_BAND_64K);

		String line = consumeCapabilities(pckIn,
				serverOption -> reqBuilder.addServerOption(serverOption),
				agent -> reqBuilder.setAgent(agent));

		if (line == PacketLineIn.END) {
			return reqBuilder.build();
		}

		if (line != PacketLineIn.DELIM) {
			throw new PackProtocolException(
					MessageFormat.format(JGitText.get().unexpectedPacketLine,
							line));
		}

		boolean filterReceived = false;
		while ((line = pckIn.readString()) != PacketLineIn.END) {
			if (line.startsWith("want ")) { //$NON-NLS-1$
				reqBuilder.addWantId(ObjectId.fromString(line.substring(5)));
			} else if (transferConfig.isAllowRefInWant()
					&& line.startsWith(OPTION_WANT_REF + " ")) { //$NON-NLS-1$
				reqBuilder.addWantedRef(line.substring(OPTION_WANT_REF.length() + 1));
			} else if (line.startsWith("have ")) { //$NON-NLS-1$
				reqBuilder.addPeerHas(ObjectId.fromString(line.substring(5)));
			} else if (line.equals("done")) { //$NON-NLS-1$
				reqBuilder.setDoneReceived();
			} else if (line.equals(OPTION_THIN_PACK)) {
				reqBuilder.addClientCapability(OPTION_THIN_PACK);
			} else if (line.equals(OPTION_NO_PROGRESS)) {
				reqBuilder.addClientCapability(OPTION_NO_PROGRESS);
			} else if (line.equals(OPTION_INCLUDE_TAG)) {
				reqBuilder.addClientCapability(OPTION_INCLUDE_TAG);
			} else if (line.equals(OPTION_OFS_DELTA)) {
				reqBuilder.addClientCapability(OPTION_OFS_DELTA);
			} else if (line.startsWith("shallow ")) { //$NON-NLS-1$
				reqBuilder.addClientShallowCommit(
						ObjectId.fromString(line.substring(8)));
			} else if (line.startsWith("deepen ")) { //$NON-NLS-1$
				int parsedDepth = Integer.parseInt(line.substring(7));
				if (parsedDepth <= 0) {
					throw new PackProtocolException(
							MessageFormat.format(JGitText.get().invalidDepth,
									Integer.valueOf(parsedDepth)));
				}
				if (reqBuilder.getDeepenSince() != 0) {
					throw new PackProtocolException(
							JGitText.get().deepenSinceWithDeepen);
				}
				if (reqBuilder.hasDeepenNotRefs()) {
					throw new PackProtocolException(
							JGitText.get().deepenNotWithDeepen);
				}
				reqBuilder.setDepth(parsedDepth);
			} else if (line.startsWith("deepen-not ")) { //$NON-NLS-1$
				reqBuilder.addDeepenNotRef(line.substring(11));
				if (reqBuilder.getDepth() != 0) {
					throw new PackProtocolException(
							JGitText.get().deepenNotWithDeepen);
				}
			} else if (line.equals(OPTION_DEEPEN_RELATIVE)) {
				reqBuilder.addClientCapability(OPTION_DEEPEN_RELATIVE);
			} else if (line.startsWith("deepen-since ")) { //$NON-NLS-1$
				int ts = Integer.parseInt(line.substring(13));
				if (ts <= 0) {
					throw new PackProtocolException(MessageFormat
							.format(JGitText.get().invalidTimestamp, line));
				}
				if (reqBuilder.getDepth() != 0) {
					throw new PackProtocolException(
							JGitText.get().deepenSinceWithDeepen);
				}
				reqBuilder.setDeepenSince(ts);
			} else if (transferConfig.isAllowFilter()
					&& line.startsWith(OPTION_FILTER + ' ')) {
				if (filterReceived) {
					throw new PackProtocolException(
							JGitText.get().tooManyFilters);
				}
				filterReceived = true;
				reqBuilder.setFilterSpec(FilterSpec.fromFilterLine(
						line.substring(OPTION_FILTER.length() + 1)));
			} else {
				throw new PackProtocolException(MessageFormat
						.format(JGitText.get().unexpectedPacketLine, line));
			}
		}

		return reqBuilder.build();
	}

	/**
	 * Parse the incoming ls-refs request arguments from the wire. This is meant
	 * for calling immediately after the caller has consumed a "command=ls-refs"
	 * line indicating the beginning of a ls-refs request.
	 *
	 * The incoming PacketLineIn is consumed until an END line, but the caller
	 * is responsible for closing it (if needed)
	 *
	 * @param pckIn
	 *            incoming lines. This method will read until an END line.
	 * @return a LsRefsV2Request object with the data received in the wire.
	 * @throws PackProtocolException
	 *             for inconsistencies in the protocol (e.g. unexpected lines)
	 * @throws IOException
	 *             reporting problems reading the incoming messages from the
	 *             wire
	 */
	LsRefsV2Request parseLsRefsRequest(PacketLineIn pckIn)
			throws PackProtocolException, IOException {
		LsRefsV2Request.Builder builder = LsRefsV2Request.builder();
		List<String> prefixes = new ArrayList<>();

		String line = consumeCapabilities(pckIn,
				serverOption -> builder.addServerOption(serverOption),
				agent -> builder.setAgent(agent));

		if (line == PacketLineIn.END) {
			return builder.build();
		}

		if (line != PacketLineIn.DELIM) {
			throw new PackProtocolException(MessageFormat
					.format(JGitText.get().unexpectedPacketLine, line));
		}

		while ((line = pckIn.readString()) != PacketLineIn.END) {
			if (line.equals("peel")) { //$NON-NLS-1$
				builder.setPeel(true);
			} else if (line.equals("symrefs")) { //$NON-NLS-1$
				builder.setSymrefs(true);
			} else if (line.startsWith("ref-prefix ")) { //$NON-NLS-1$
				prefixes.add(line.substring("ref-prefix ".length())); //$NON-NLS-1$
			} else {
				throw new PackProtocolException(MessageFormat
						.format(JGitText.get().unexpectedPacketLine, line));
			}
		}

		return builder.setRefPrefixes(prefixes).build();
	}

}