FirstWant: Parse client session-id if received.

In protocol V0 the client capabilities are appended to the first line.
Parsing session-id is currently only supported during a ReceivePack
operation. This change will parse the client session-id capability if
it has been sent by the client.

If the server sends the session-id capability to the client. The client
may respond with a session ID of its own. FirstWant.fromLine will now
parse the ID and make it available via the getClientSID method.

This change does not add support to send the session-id capability from
the server. The change is necessary to support session-id in UploadPack.

Change-Id: Id3fe44fdf9a72984ee3de9cf40cc4e71d434df4a
Signed-off-by: Josh Brown <sjoshbrown@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/transport/parser/FirstWantTest.java

@@ -27,7 +27,8 @@ public class FirstWantTest {
 	@Test
 	public void testFirstWantWithOptions() throws PackProtocolException {
 		String line = "want b9d4d1eb2f93058814480eae9e1b67550f46ee38 "
-				+ "no-progress include-tag ofs-delta agent=JGit/unknown";
+				+ "no-progress include-tag ofs-delta agent=JGit/unknown "
+				+ "session-id=the.client.sid";
 
 		FirstWant r = FirstWant.fromLine(line);
 		assertEquals("want b9d4d1eb2f93058814480eae9e1b67550f46ee38",
@@ -37,6 +38,7 @@ public void testFirstWantWithOptions() throws PackProtocolException {
 				Arrays.asList("no-progress", "include-tag", "ofs-delta"));
 		assertEquals(expectedCapabilities, capabilities);
 		assertEquals("JGit/unknown", r.getAgent());
+		assertEquals("the.client.sid", r.getClientSID());
 	}
 
 	@Test
@@ -94,4 +96,12 @@ public void testFirstWantValidAgentName() throws PackProtocolException {
 		assertEquals(r.getCapabilities().size(), 0);
 		assertEquals("pack.age/Version", r.getAgent());
 	}
+
+	@Test
+	public void testFirstWantValidSessionID() throws PackProtocolException {
+		FirstWant r = FirstWant
+				.fromLine(makeFirstWantLine("session-id=client.session.id"));
+		assertEquals(r.getCapabilities().size(), 0);
+		assertEquals("client.session.id", r.getClientSID());
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/parser/FirstWant.java

@@ -10,6 +10,7 @@
 package org.eclipse.jgit.internal.transport.parser;
 
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_AGENT;
+import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SESSION_ID;
 
 import java.util.Collections;
 import java.util.HashSet;
@@ -43,8 +44,13 @@ public class FirstWant {
 	@Nullable
 	private final String agent;
 
+	@Nullable
+	private final String clientSID;
+
 	private static final String AGENT_PREFIX = OPTION_AGENT + '=';
 
+	private static final String SESSION_ID_PREFIX = OPTION_SESSION_ID + '=';
+
 	/**
 	 * Parse the first want line in the protocol v0/v1 pack negotiation.
 	 *
@@ -58,6 +64,7 @@ public static FirstWant fromLine(String line) throws PackProtocolException {
 		String wantLine;
 		Set<String> capabilities;
 		String agent = null;
+		String clientSID = null;
 
 		if (line.length() > 45) {
 			String opt = line.substring(45);
@@ -70,6 +77,9 @@ public static FirstWant fromLine(String line) throws PackProtocolException {
 			for (String clientCapability : opt.split(" ")) { //$NON-NLS-1$
 				if (clientCapability.startsWith(AGENT_PREFIX)) {
 					agent = clientCapability.substring(AGENT_PREFIX.length());
+				} else if (clientCapability.startsWith(SESSION_ID_PREFIX)) {
+					clientSID = clientCapability
+							.substring(SESSION_ID_PREFIX.length());
 				} else {
 					opts.add(clientCapability);
 				}
@@ -81,14 +91,15 @@ public static FirstWant fromLine(String line) throws PackProtocolException {
 			capabilities = Collections.emptySet();
 		}
 
-		return new FirstWant(wantLine, capabilities, agent);
+		return new FirstWant(wantLine, capabilities, agent, clientSID);
 	}
 
 	private FirstWant(String line, Set<String> capabilities,
-			@Nullable String agent) {
+			@Nullable String agent, @Nullable String clientSID) {
 		this.line = line;
 		this.capabilities = capabilities;
 		this.agent = agent;
+		this.clientSID = clientSID;
 	}
 
 	/** @return non-capabilities part of the line. */
@@ -98,7 +109,7 @@ public String getLine() {
 
 	/**
 	 * @return capabilities parsed from the line as an immutable set (excluding
-	 *         agent).
+	 *         agent and session-id).
 	 */
 	public Set<String> getCapabilities() {
 		return capabilities;
@@ -109,4 +120,10 @@ public Set<String> getCapabilities() {
 	public String getAgent() {
 		return agent;
 	}
+
+	/** @return client session-id parsed from the line. */
+	@Nullable
+	public String getClientSID() {
+		return clientSID;
+	}
 }