Extract protocol v2 fetch request parsing to its own class

The parsing code for protocol v2 fetch doesn't have any dependency on
the rest of UploadPack.

Move it to its own class. This makes testing easier (no need to
instantiate the full UploadPack), simplifies the code in UploadPack and
increases modularity.

At the moment, the parser needs to know about the reference database to
validate incoming references. This dependency could be easily removed
moving the validation later in the flow, after the parsing, where other
validations are already happening. Postponing that to keep this patch
about moving unmodified code around.

Change-Id: I7ad29a6b99caa7c12c06f5a7f30ab6a5f6e44dc7
Signed-off-by: Ivan Frade <ifrade@google.com>

2 files changed, 249 insertions, 137 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/ProtocolV2Parser.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/ProtocolV2Parser.java
new file mode 100644
index 0000000000..eae2c6edb9
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/ProtocolV2Parser.java
@@ -0,0 +1,244 @@
+/*
+ * 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;
+ * 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.transport.GitProtocolConstants.OPTION_DEEPEN_RELATIVE;
+import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_FILTER;
+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_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 org.eclipse.jgit.errors.PackProtocolException;
+import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.RefDatabase;
+
+/**
+ * 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;
+	}
+
+	/**
+	 * 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.
+	 *
+	 * This operation requires the reference database to validate incoming
+	 * references.
+	 *
+	 * @param pckIn
+	 *            incoming lines
+	 * @param refdb
+	 *            reference database (to validate that received references exist
+	 *            and point to valid objects)
+	 * @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 or
+	 *             accessing the ref database.
+	 */
+	FetchV2Request parseFetchRequest(PacketLineIn pckIn, RefDatabase refdb)
+			throws PackProtocolException, IOException {
+		FetchV2Request.Builder reqBuilder = FetchV2Request.builder();
+
+		// Packs are always sent multiplexed and using full 64K
+		// lengths.
+		reqBuilder.addOption(OPTION_SIDE_BAND_64K);
+
+		String line;
+
+		// Currently, we do not support any capabilities, so the next
+		// line is DELIM.
+		if ((line = pckIn.readString()) != 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.addWantsIds(ObjectId.fromString(line.substring(5)));
+			} else if (transferConfig.isAllowRefInWant()
+					&& line.startsWith(OPTION_WANT_REF + " ")) { //$NON-NLS-1$
+				String refName = line.substring(OPTION_WANT_REF.length() + 1);
+				// TODO(ifrade): This validation should be done after the
+				// protocol parsing. It is not a protocol problem asking for an
+				// unexisting ref and we wouldn't need the ref database here
+				Ref ref = refdb.exactRef(refName);
+				if (ref == null) {
+					throw new PackProtocolException(MessageFormat
+							.format(JGitText.get().invalidRefName, refName));
+				}
+				ObjectId oid = ref.getObjectId();
+				if (oid == null) {
+					throw new PackProtocolException(MessageFormat
+							.format(JGitText.get().invalidRefName, refName));
+				}
+				reqBuilder.addWantedRef(refName, oid);
+				reqBuilder.addWantsIds(oid);
+			} 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.addOption(OPTION_THIN_PACK);
+			} else if (line.equals(OPTION_NO_PROGRESS)) {
+				reqBuilder.addOption(OPTION_NO_PROGRESS);
+			} else if (line.equals(OPTION_INCLUDE_TAG)) {
+				reqBuilder.addOption(OPTION_INCLUDE_TAG);
+			} else if (line.equals(OPTION_OFS_DELTA)) {
+				reqBuilder.addOption(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.addOption(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.setFilterBlobLimit(filterLine(
+						line.substring(OPTION_FILTER.length() + 1)));
+			} else {
+				throw new PackProtocolException(MessageFormat
+						.format(JGitText.get().unexpectedPacketLine, line));
+			}
+		}
+
+		return reqBuilder.build();
+	}
+
+	/**
+	 * Process the content of "filter" line from the protocol. It has a shape
+	 * like "blob:none" or "blob:limit=N", with limit a positive number.
+	 *
+	 * @param blobLine
+	 *            the content of the "filter" line in the protocol
+	 * @return N, the limit, defaulting to 0 if "none"
+	 * @throws PackProtocolException
+	 *             invalid filter because due to unrecognized format or
+	 *             negative/non-numeric filter.
+	 */
+	static long filterLine(String blobLine) throws PackProtocolException {
+		long blobLimit = -1;
+
+		if (blobLine.equals("blob:none")) { //$NON-NLS-1$
+			blobLimit = 0;
+		} else if (blobLine.startsWith("blob:limit=")) { //$NON-NLS-1$
+			try {
+				blobLimit = Long
+						.parseLong(blobLine.substring("blob:limit=".length())); //$NON-NLS-1$
+			} catch (NumberFormatException e) {
+				throw new PackProtocolException(MessageFormat
+						.format(JGitText.get().invalidFilter, blobLine));
+			}
+		}
+		/*
+		 * We must have (1) either "blob:none" or "blob:limit=" set (because we
+		 * only support blob size limits for now), and (2) if the latter, then
+		 * it must be nonnegative. Throw if (1) or (2) is not met.
+		 */
+		if (blobLimit < 0) {
+			throw new PackProtocolException(
+					MessageFormat.format(JGitText.get().invalidFilter, blobLine));
+		}
+
+		return blobLimit;
+	}
+
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index b1d7e5447c..cd7290edcd 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -63,7 +63,6 @@ import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SHALLOW;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDE_BAND;
 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.ByteArrayOutputStream;
 import java.io.EOFException;
@@ -944,12 +943,6 @@ public class UploadPack {
 	}
 
 	private void fetchV2() throws IOException {
-		FetchV2Request.Builder reqBuilder = FetchV2Request.builder();
-
-		// Packs are always sent multiplexed and using full 64K
-		// lengths.
-		reqBuilder.addOption(OPTION_SIDE_BAND_64K);
-
 		// Depending on the requestValidator, #processHaveLines may
 		// require that advertised be set. Set it only in the required
 		// circumstances (to avoid a full ref lookup in the case that
@@ -962,105 +955,11 @@ public class UploadPack {
 			advertised = refIdSet(getAdvertisedOrDefaultRefs().values());
 		}
 
-		String line;
-
-		// Currently, we do not support any capabilities, so the next
-		// line is DELIM.
-		if ((line = pckIn.readString()) != PacketLineIn.DELIM) {
-			throw new PackProtocolException(MessageFormat
-					.format(JGitText.get().unexpectedPacketLine, line));
-		}
-
-		boolean includeTag = false;
-		boolean filterReceived = false;
-		while ((line = pckIn.readString()) != PacketLineIn.END) {
-			if (line.startsWith("want ")) { //$NON-NLS-1$
-				reqBuilder.addWantsIds(ObjectId.fromString(line.substring(5)));
-			} else if (transferConfig.isAllowRefInWant() &&
-					line.startsWith(OPTION_WANT_REF + " ")) { //$NON-NLS-1$
-				String refName = line.substring(OPTION_WANT_REF.length() + 1);
-				Ref ref = db.getRefDatabase().exactRef(refName);
-				if (ref == null) {
-					throw new PackProtocolException(
-							MessageFormat.format(JGitText.get().invalidRefName,
-								refName));
-				}
-				ObjectId oid = ref.getObjectId();
-				if (oid == null) {
-					throw new PackProtocolException(
-							MessageFormat.format(JGitText.get().invalidRefName,
-								refName));
-				}
-				reqBuilder.addWantedRef(refName, oid);
-				reqBuilder.addWantsIds(oid);
-			} 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.addOption(OPTION_THIN_PACK);
-			} else if (line.equals(OPTION_NO_PROGRESS)) {
-				reqBuilder.addOption(OPTION_NO_PROGRESS);
-			} else if (line.equals(OPTION_INCLUDE_TAG)) {
-				reqBuilder.addOption(OPTION_INCLUDE_TAG);
-				includeTag = true;
-			} else if (line.equals(OPTION_OFS_DELTA)) {
-				reqBuilder.addOption(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.addOption(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.setFilterBlobLimit(parseFilter(
-						line.substring(OPTION_FILTER.length() + 1)));
-			} else {
-				throw new PackProtocolException(MessageFormat
-						.format(JGitText.get().unexpectedPacketLine, line));
-			}
-		}
+		ProtocolV2Parser parser = new ProtocolV2Parser(transferConfig);
+		FetchV2Request req = parser.parseFetchRequest(pckIn,
+				db.getRefDatabase());
 		rawOut.stopBuffering();
 
-		FetchV2Request req = reqBuilder.build();
 		protocolV2Hook.onFetch(req);
 
 		// TODO(ifrade): Refactor to pass around the Request object, instead of
@@ -1139,7 +1038,7 @@ public class UploadPack {
 				pckOut.writeDelim();
 			pckOut.writeString("packfile\n"); //$NON-NLS-1$
 			sendPack(new PackStatistics.Accumulator(),
-					includeTag
+					req.getOptions().contains(OPTION_INCLUDE_TAG)
 						? db.getRefDatabase().getRefsByPrefix(R_TAGS)
 						: null,
 					unshallowCommits);
@@ -1459,37 +1358,6 @@ public class UploadPack {
 		return msgOut;
 	}
 
-	private long parseFilter(String arg) throws PackProtocolException {
-		long blobLimit = -1;
-
-		if (arg.equals("blob:none")) { //$NON-NLS-1$
-			blobLimit = 0;
-		} else if (arg.startsWith("blob:limit=")) { //$NON-NLS-1$
-			try {
-				blobLimit = Long.parseLong(
-						arg.substring("blob:limit=".length())); //$NON-NLS-1$
-			} catch (NumberFormatException e) {
-				throw new PackProtocolException(
-						MessageFormat.format(JGitText.get().invalidFilter,
-								arg));
-			}
-		}
-		/*
-		 * We must have (1) either "blob:none" or
-		 * "blob:limit=" set (because we only support
-		 * blob size limits for now), and (2) if the
-		 * latter, then it must be nonnegative. Throw
-		 * if (1) or (2) is not met.
-		 */
-		if (blobLimit < 0) {
-			throw new PackProtocolException(
-					MessageFormat.format(JGitText.get().invalidFilter,
-							arg));
-		}
-
-		return blobLimit;
-	}
-
 	private void recvWants() throws IOException {
 		boolean isFirst = true;
 		boolean filterReceived = false;
@@ -1530,7 +1398,7 @@ public class UploadPack {
 				}
 				filterReceived = true;
 
-				filterBlobLimit = parseFilter(arg);
+				filterBlobLimit = ProtocolV2Parser.filterLine(arg);
 				continue;
 			}