Reset SSH connection and credentials on "Auth fail"

When SSH user/password authentication failed this may have been caused
by changed credentials on the server side. When the SSH credentials of a
user change the SSH connection needs to be re-established and
credentials which may have been stored by the credentials provider
need to be reset in order to enable prompting for the new credentials.

Bug: 356233
Change-Id: I7d64c5f39b68a9687c858bb68a961616eabbc751
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -134,4 +134,13 @@ public abstract class CredentialsProvider {
 			throws UnsupportedCredentialItem {
 		return get(uri, items.toArray(new CredentialItem[items.size()]));
 	}
+
+	/**
+	 * Reset the credentials provider for the given URI
+	 *
+	 * @param uri
+	 */
+	public void reset(URIish uri) {
+		// default does nothing
+	}
 }

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

@@ -106,26 +106,29 @@ public abstract class JschConfigSessionFactory extends SshSessionFactory {
 			if (user == null)
 				user = hc.getUser();
 
-			final Session session = createSession(hc, user, host, port, fs);
-			if (pass != null)
-				session.setPassword(pass);
-			final String strictHostKeyCheckingPolicy = hc
-					.getStrictHostKeyChecking();
-			if (strictHostKeyCheckingPolicy != null)
-				session.setConfig("StrictHostKeyChecking",
-						strictHostKeyCheckingPolicy);
-			final String pauth = hc.getPreferredAuthentications();
-			if (pauth != null)
-				session.setConfig("PreferredAuthentications", pauth);
-			if (credentialsProvider != null
-				&& (!hc.isBatchMode() || !credentialsProvider.isInteractive())) {
-				session.setUserInfo(new CredentialsProviderUserInfo(session,
-						credentialsProvider));
-			}
-			configure(hc, session);
+			Session session = createSession(credentialsProvider, fs, user,
+					pass, host, port, hc);
 
-			if (!session.isConnected())
-				session.connect(tms);
+			int retries = 0;
+			while (!session.isConnected() && retries < 3) {
+				try {
+					retries++;
+					session.connect(tms);
+				} catch (JSchException e) {
+					session.disconnect();
+					session = null;
+					// if authentication failed maybe credentials changed at the
+					// remote end therefore reset credentials and retry
+					if (credentialsProvider != null && e.getCause() == null
+							&& e.getMessage().equals("Auth fail")) {
+						credentialsProvider.reset(uri);
+						session = createSession(credentialsProvider, fs, user,
+								pass, host, port, hc);
+					} else {
+						throw e;
+					}
+				}
+			}
 
 			return new JschSession(session, uri);
 
@@ -140,9 +143,32 @@ public abstract class JschConfigSessionFactory extends SshSessionFactory {
 
 	}
 
+	private Session createSession(CredentialsProvider credentialsProvider,
+			FS fs, String user, final String pass, String host, int port,
+			final OpenSshConfig.Host hc) throws JSchException {
+		final Session session = createSession(hc, user, host, port, fs);
+		if (pass != null)
+			session.setPassword(pass);
+		final String strictHostKeyCheckingPolicy = hc
+				.getStrictHostKeyChecking();
+		if (strictHostKeyCheckingPolicy != null)
+			session.setConfig("StrictHostKeyChecking",
+					strictHostKeyCheckingPolicy);
+		final String pauth = hc.getPreferredAuthentications();
+		if (pauth != null)
+			session.setConfig("PreferredAuthentications", pauth);
+		if (credentialsProvider != null
+				&& (!hc.isBatchMode() || !credentialsProvider.isInteractive())) {
+			session.setUserInfo(new CredentialsProviderUserInfo(session,
+					credentialsProvider));
+		}
+		configure(hc, session);
+		return session;
+	}
+
 	/**
 	 * Create a new remote session for the requested address.
-	 * 
+	 *
 	 * @param hc
 	 *            host configuration
 	 * @param user