BasePackConnection: Check for expected length of ref advertisement

When a server sends a ref advertisement using protocol v2 it contains
lines other than ref names and sha1s.  Attempting to get the sha1 out
of such a line using the substring method can result in a SIOOB error
when it doesn't actually contain the sha1 and ref name.

Add a check that the line is of the expected length, and subsequently
that the extracted object id is valid, and if not throw an exception.

Change-Id: Id92fe66ff8b6deb2cf987d81929f8d0602c399f4
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties

@@ -390,6 +390,7 @@ invalidPathPeriodAtEndWindows=Invalid path (period at end is ignored by Windows)
 invalidPathSpaceAtEndWindows=Invalid path (space at end is ignored by Windows): {0}
 invalidPathReservedOnWindows=Invalid path (''{0}'' is reserved on Windows): {1}
 invalidRedirectLocation=Invalid redirect location {0} -> {1}
+invalidRefAdvertisementLine=Invalid ref advertisement line: ''{1}''
 invalidReflogRevision=Invalid reflog revision: {0}
 invalidRefName=Invalid ref name: {0}
 invalidReftableBlock=Invalid reftable block

org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java

@@ -451,6 +451,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String invalidPathSpaceAtEndWindows;
 	/***/ public String invalidPathReservedOnWindows;
 	/***/ public String invalidRedirectLocation;
+	/***/ public String invalidRefAdvertisementLine;
 	/***/ public String invalidReflogRevision;
 	/***/ public String invalidRefName;
 	/***/ public String invalidReftableBlock;

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

@@ -57,6 +57,7 @@ import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.Set;
 
+import org.eclipse.jgit.errors.InvalidObjectIdException;
 import org.eclipse.jgit.errors.NoRemoteRepositoryException;
 import org.eclipse.jgit.errors.PackProtocolException;
 import org.eclipse.jgit.errors.RemoteRepositoryException;
@@ -222,6 +223,10 @@ abstract class BasePackConnection extends BaseConnection {
 				}
 			}
 
+			// Expecting to get a line in the form "sha1 refname"
+			if (line.length() < 41 || line.charAt(40) != ' ') {
+				throw invalidRefAdvertisementLine(line);
+			}
 			String name = line.substring(41, line.length());
 			if (avail.isEmpty() && name.equals("capabilities^{}")) { //$NON-NLS-1$
 				// special line from git-receive-pack to show
@@ -229,7 +234,12 @@ abstract class BasePackConnection extends BaseConnection {
 				continue;
 			}
 
-			final ObjectId id = ObjectId.fromString(line.substring(0, 40));
+			final ObjectId id;
+			try {
+				id  = ObjectId.fromString(line.substring(0, 40));
+			} catch (InvalidObjectIdException e) {
+				throw invalidRefAdvertisementLine(line);
+			}
 			if (name.equals(".have")) { //$NON-NLS-1$
 				additionalHaves.add(id);
 			} else if (name.endsWith("^{}")) { //$NON-NLS-1$
@@ -318,6 +328,10 @@ abstract class BasePackConnection extends BaseConnection {
 		return new PackProtocolException(uri, MessageFormat.format(JGitText.get().duplicateAdvertisementsOf, name));
 	}
 
+	private PackProtocolException invalidRefAdvertisementLine(String line) {
+		return new PackProtocolException(uri, MessageFormat.format(JGitText.get().invalidRefAdvertisementLine, line));
+	}
+
 	/** {@inheritDoc} */
 	@Override
 	public void close() {