gitblit/src/main/java/com/gitblit/manager/AuthenticationManager.java

/*
 * Copyright 2013 gitblit.com.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.gitblit.manager;

import java.nio.charset.Charset;
import java.security.Principal;
import java.text.MessageFormat;
import java.util.*;
import java.util.concurrent.TimeUnit;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.gitblit.Constants;
import com.gitblit.Constants.AccountType;
import com.gitblit.Constants.AuthenticationType;
import com.gitblit.Constants.Role;
import com.gitblit.IStoredSettings;
import com.gitblit.Keys;
import com.gitblit.auth.AuthenticationProvider;
import com.gitblit.auth.AuthenticationProvider.UsernamePasswordAuthenticationProvider;
import com.gitblit.auth.HtpasswdAuthProvider;
import com.gitblit.auth.HttpHeaderAuthProvider;
import com.gitblit.auth.LdapAuthProvider;
import com.gitblit.auth.PAMAuthProvider;
import com.gitblit.auth.RedmineAuthProvider;
import com.gitblit.auth.SalesforceAuthProvider;
import com.gitblit.auth.WindowsAuthProvider;
import com.gitblit.models.TeamModel;
import com.gitblit.models.UserModel;
import com.gitblit.transport.ssh.SshKey;
import com.gitblit.utils.Base64;
import com.gitblit.utils.HttpUtils;
import com.gitblit.utils.PasswordHash;
import com.gitblit.utils.StringUtils;
import com.gitblit.utils.X509Utils.X509Metadata;
import com.google.inject.Inject;
import com.google.inject.Singleton;

/**
 * The authentication manager handles user login & logout.
 *
 * @author James Moger
 *
 */
@Singleton
public class AuthenticationManager implements IAuthenticationManager {

	private final Logger logger = LoggerFactory.getLogger(getClass());

	private final IStoredSettings settings;

	private final IRuntimeManager runtimeManager;

	private final IUserManager userManager;

	private final List<AuthenticationProvider> authenticationProviders;

	private final Map<String, Class<? extends AuthenticationProvider>> providerNames;

	private final Map<String, String> legacyRedirects;

	@Inject
	public AuthenticationManager(
			IRuntimeManager runtimeManager,
			IUserManager userManager) {

		this.settings = runtimeManager.getSettings();
		this.runtimeManager = runtimeManager;
		this.userManager = userManager;
		this.authenticationProviders = new ArrayList<AuthenticationProvider>();

		// map of shortcut provider names
		providerNames = new HashMap<String, Class<? extends AuthenticationProvider>>();
		providerNames.put("htpasswd", HtpasswdAuthProvider.class);
		providerNames.put("httpheader", HttpHeaderAuthProvider.class);
		providerNames.put("ldap", LdapAuthProvider.class);
		providerNames.put("pam", PAMAuthProvider.class);
		providerNames.put("redmine", RedmineAuthProvider.class);
		providerNames.put("salesforce", SalesforceAuthProvider.class);
		providerNames.put("windows", WindowsAuthProvider.class);

		// map of legacy external user services
		legacyRedirects = new HashMap<String, String>();
		legacyRedirects.put("com.gitblit.HtpasswdUserService", "htpasswd");
		legacyRedirects.put("com.gitblit.LdapUserService", "ldap");
		legacyRedirects.put("com.gitblit.PAMUserService", "pam");
		legacyRedirects.put("com.gitblit.RedmineUserService", "redmine");
		legacyRedirects.put("com.gitblit.SalesforceUserService", "salesforce");
		legacyRedirects.put("com.gitblit.WindowsUserService", "windows");
	}

	@Override
	public AuthenticationManager start() {
		// automatically adjust legacy configurations
		String realm = settings.getString(Keys.realm.userService, "${baseFolder}/users.conf");
		if (legacyRedirects.containsKey(realm)) {
			logger.warn("");
			logger.warn(Constants.BORDER2);
			logger.warn(" IUserService '{}' is obsolete!", realm);
			logger.warn(" Please set '{}={}'", "realm.authenticationProviders", legacyRedirects.get(realm));
			logger.warn(Constants.BORDER2);
			logger.warn("");

			// conditionally override specified authentication providers
			if (StringUtils.isEmpty(settings.getString(Keys.realm.authenticationProviders, null))) {
				settings.overrideSetting(Keys.realm.authenticationProviders, legacyRedirects.get(realm));
			}
		}

		// instantiate and setup specified authentication providers
		List<String> providers = settings.getStrings(Keys.realm.authenticationProviders);
		if (providers.isEmpty()) {
			logger.info("External authentication disabled.");
		} else {
			for (String provider : providers) {
				try {
					Class<?> authClass;
					if (providerNames.containsKey(provider)) {
						// map the name -> class
						authClass = providerNames.get(provider);
					} else {
						// reflective lookup
						authClass = Class.forName(provider);
					}
					logger.info("setting up {}", authClass.getName());
					AuthenticationProvider authImpl = (AuthenticationProvider) authClass.newInstance();
					authImpl.setup(runtimeManager, userManager);
					authenticationProviders.add(authImpl);
				} catch (Exception e) {
					logger.error("", e);
				}
			}
		}
		return this;
	}

	@Override
	public AuthenticationManager stop() {
		for (AuthenticationProvider provider : authenticationProviders) {
			try {
				provider.stop();
			} catch (Exception e) {
				logger.error("Failed to stop " + provider.getClass().getSimpleName(), e);
			}
		}
		return this;
	}

	public void addAuthenticationProvider(AuthenticationProvider prov) {
		authenticationProviders.add(prov);
	}

	/**
	 * Used to handle authentication for page requests.
	 *
	 * This allows authentication to occur based on the contents of the request
	 * itself. If no configured @{AuthenticationProvider}s authenticate succesffully,
	 * a request for login will be shown.
	 *
	 * Authentication by X509Certificate is tried first and then by cookie.
	 *
	 * @param httpRequest
	 * @return a user object or null
	 */
	@Override
	public UserModel authenticate(HttpServletRequest httpRequest) {
		return authenticate(httpRequest, false);
	}

	/**
	 * Authenticate a user based on HTTP request parameters.
	 *
	 * Authentication by custom HTTP header, servlet container principal, X509Certificate, cookie,
	 * and finally BASIC header.
	 *
	 * @param httpRequest
	 * @param requiresCertificate
	 * @return a user object or null
	 */
	@Override
	public UserModel authenticate(HttpServletRequest httpRequest, boolean requiresCertificate) {

		// Check if this request has already been authenticated, and trust that instead of re-processing
		String reqAuthUser = (String) httpRequest.getAttribute(Constants.ATTRIB_AUTHUSER);
		if (!StringUtils.isEmpty(reqAuthUser)) {
			logger.debug("Called servlet authenticate when request is already authenticated.");
			return userManager.getUserModel(reqAuthUser);
		}

		// try to authenticate by servlet container principal
		if (!requiresCertificate) {
			Principal principal = httpRequest.getUserPrincipal();
			if (principal != null) {
				String username = principal.getName();
				if (!StringUtils.isEmpty(username)) {
					boolean internalAccount = userManager.isInternalAccount(username);
					UserModel user = userManager.getUserModel(username);
					if (user != null) {
						// existing user
						flagRequest(httpRequest, AuthenticationType.CONTAINER, user.username);
						logger.debug(MessageFormat.format("{0} authenticated by servlet container principal from {1}",
								user.username, httpRequest.getRemoteAddr()));
						return validateAuthentication(user, AuthenticationType.CONTAINER);
					} else if (settings.getBoolean(Keys.realm.container.autoCreateAccounts, false)
							&& !internalAccount) {
						// auto-create user from an authenticated container principal
						user = new UserModel(username.toLowerCase());
						user.displayName = username;
						user.password = Constants.EXTERNAL_ACCOUNT;
						user.accountType = AccountType.CONTAINER;
						
						// Try to extract user's informations for the session
						// it uses "realm.container.autoAccounts.*" as the attribute name to look for
						HttpSession session = httpRequest.getSession();
						String emailAddress = resolveAttribute(session, Keys.realm.container.autoAccounts.emailAddress);
						if(emailAddress != null) {
							user.emailAddress = emailAddress;
						}
						String displayName = resolveAttribute(session, Keys.realm.container.autoAccounts.displayName);
						if(displayName != null) {
							user.displayName = displayName;
						}
						String userLocale = resolveAttribute(session, Keys.realm.container.autoAccounts.locale);
						if(userLocale != null) {
							user.getPreferences().setLocale(userLocale);
						}
						String adminRole = settings.getString(Keys.realm.container.autoAccounts.adminRole, null);
						if(adminRole != null && ! adminRole.isEmpty()) {
							if(httpRequest.isUserInRole(adminRole)) {
								user.canAdmin = true;
							}
						}
						
						userManager.updateUserModel(user);
						flagRequest(httpRequest, AuthenticationType.CONTAINER, user.username);
						logger.debug(MessageFormat.format("{0} authenticated and created by servlet container principal from {1}",
								user.username, httpRequest.getRemoteAddr()));
						return validateAuthentication(user, AuthenticationType.CONTAINER);
					} else if (!internalAccount) {
						logger.warn(MessageFormat.format("Failed to find UserModel for {0}, attempted servlet container authentication from {1}",
								principal.getName(), httpRequest.getRemoteAddr()));
					}
				}
			}
		}

		// try to authenticate by certificate
		boolean checkValidity = settings.getBoolean(Keys.git.enforceCertificateValidity, true);
		String [] oids = settings.getStrings(Keys.git.certificateUsernameOIDs).toArray(new String[0]);
		UserModel model = HttpUtils.getUserModelFromCertificate(httpRequest, checkValidity, oids);
		if (model != null) {
			// grab real user model and preserve certificate serial number
			UserModel user = userManager.getUserModel(model.username);
			X509Metadata metadata = HttpUtils.getCertificateMetadata(httpRequest);
			if (user != null) {
				flagRequest(httpRequest, AuthenticationType.CERTIFICATE, user.username);
				logger.debug(MessageFormat.format("{0} authenticated by client certificate {1} from {2}",
						user.username, metadata.serialNumber, httpRequest.getRemoteAddr()));
				return validateAuthentication(user, AuthenticationType.CERTIFICATE);
			} else {
				logger.warn(MessageFormat.format("Failed to find UserModel for {0}, attempted client certificate ({1}) authentication from {2}",
						model.username, metadata.serialNumber, httpRequest.getRemoteAddr()));
			}
		}

		if (requiresCertificate) {
			// caller requires client certificate authentication (e.g. git servlet)
			return null;
		}

		UserModel user = null;

		// try to authenticate by cookie
		String cookie = getCookie(httpRequest);
		if (!StringUtils.isEmpty(cookie)) {
			user = userManager.getUserModel(cookie.toCharArray());
			if (user != null) {
				flagRequest(httpRequest, AuthenticationType.COOKIE, user.username);
				logger.debug(MessageFormat.format("{0} authenticated by cookie from {1}",
					user.username, httpRequest.getRemoteAddr()));
				return validateAuthentication(user, AuthenticationType.COOKIE);
			}
		}

		// try to authenticate by BASIC
		final String authorization = httpRequest.getHeader("Authorization");
		if (authorization != null && authorization.startsWith("Basic")) {
			// Authorization: Basic base64credentials
			String base64Credentials = authorization.substring("Basic".length()).trim();
			String credentials = new String(Base64.decode(base64Credentials),
					Charset.forName("UTF-8"));
			// credentials = username:password
			final String[] values = credentials.split(":", 2);

			if (values.length == 2) {
				String username = values[0];
				char[] password = values[1].toCharArray();
				user = authenticate(username, password, httpRequest.getRemoteAddr());
				if (user != null) {
					flagRequest(httpRequest, AuthenticationType.CREDENTIALS, user.username);
					logger.debug(MessageFormat.format("{0} authenticated by BASIC request header from {1}",
							user.username, httpRequest.getRemoteAddr()));
					return validateAuthentication(user, AuthenticationType.CREDENTIALS);
				}
			}
		}

		// Check each configured AuthenticationProvider
		for (AuthenticationProvider ap : authenticationProviders) {
			UserModel authedUser = ap.authenticate(httpRequest);
			if (null != authedUser) {
				flagRequest(httpRequest, ap.getAuthenticationType(), authedUser.username);
				logger.debug(MessageFormat.format("{0} authenticated by {1} from {2} for {3}",
						authedUser.username, ap.getServiceName(), httpRequest.getRemoteAddr(),
						httpRequest.getPathInfo()));
				return validateAuthentication(authedUser, ap.getAuthenticationType());
			}
		}
		return null;
	}
	
	/**
	 * Extract given attribute from the session and return it's content
	 * it return null if attributeMapping is empty, or if the value is
	 * empty
	 * 
	 * @param session The user session
	 * @param attributeMapping
	 * @return
	 */
	private String resolveAttribute(HttpSession session, String attributeMapping) {
		String attributeName = settings.getString(attributeMapping, null);
		if(StringUtils.isEmpty(attributeName)) {
			return null;
		}
		Object attributeValue = session.getAttribute(attributeName);
		if(attributeValue == null) {
			return null;
		}
		String value = attributeValue.toString();
		if(value.isEmpty()) {
			return null;
		}
		return value;
	}

	/**
	 * Authenticate a user based on a public key.
	 *
	 * This implementation assumes that the authentication has already take place
	 * (e.g. SSHDaemon) and that this is a validation/verification of the user.
	 *
	 * @param username
	 * @param key
	 * @return a user object or null
	 */
	@Override
	public UserModel authenticate(String username, SshKey key) {
		if (username != null) {
			if (!StringUtils.isEmpty(username)) {
				UserModel user = userManager.getUserModel(username);
				if (user != null) {
					// existing user
					logger.debug(MessageFormat.format("{0} authenticated by {1} public key",
							user.username, key.getAlgorithm()));
					return validateAuthentication(user, AuthenticationType.PUBLIC_KEY);
				}
				logger.warn(MessageFormat.format("Failed to find UserModel for {0} during public key authentication",
							username));
			}
		} else {
			logger.warn("Empty user passed to AuthenticationManager.authenticate!");
		}
		return null;
	}


	/**
	 * Return the UserModel for already authenticated user.
	 *
	 * This implementation assumes that the authentication has already take place
	 * (e.g. SSHDaemon) and that this is a validation/verification of the user.
	 *
	 * @param username
	 * @return a user object or null
	 */
	@Override
	public UserModel authenticate(String username) {
		if (username != null) {
			if (!StringUtils.isEmpty(username)) {
				UserModel user = userManager.getUserModel(username);
				if (user != null) {
					// existing user
					logger.debug(MessageFormat.format("{0} authenticated externally", user.username));
					return validateAuthentication(user, AuthenticationType.CONTAINER);
				}
				logger.warn(MessageFormat.format("Failed to find UserModel for {0} during external authentication",
							username));
			}
		} else {
			logger.warn("Empty user passed to AuthenticationManager.authenticate!");
		}
		return null;
	}


	/**
	 * This method allows the authentication manager to reject authentication
	 * attempts.  It is called after the username/secret have been verified to
	 * ensure that the authentication technique has been logged.
	 *
	 * @param user
	 * @return
	 */
	protected UserModel validateAuthentication(UserModel user, AuthenticationType type) {
		if (user == null) {
			return null;
		}
		if (user.disabled) {
			// user has been disabled
			logger.warn("Rejected {} authentication attempt by disabled account \"{}\"",
					type, user.username);
			return null;
		}
		return user;
	}

	protected void flagRequest(HttpServletRequest httpRequest, AuthenticationType authenticationType, String authedUsername) {
		httpRequest.setAttribute(Constants.ATTRIB_AUTHUSER,  authedUsername);
		httpRequest.setAttribute(Constants.ATTRIB_AUTHTYPE,  authenticationType);
	}

	/**
	 * Authenticate a user based on a username and password.
	 *
	 * @param username
	 * @param password
	 * @return a user object or null
	 */
	@Override
	public UserModel authenticate(String username, char[] password, String remoteIP) {
		if (StringUtils.isEmpty(username)) {
			// can not authenticate empty username
			return null;
		}

		if (username.equalsIgnoreCase(Constants.FEDERATION_USER)) {
			// can not authenticate internal FEDERATION_USER at this point
			// it must be routed to FederationManager
			return null;
		}
		
		String usernameDecoded = StringUtils.decodeUsername(username);
		if (StringUtils.isEmpty(password)) {
			// can not authenticate empty password
			return null;
		}

		UserModel user = userManager.getUserModel(usernameDecoded);

		try {
			// try local authentication
			if (user != null && user.isLocalAccount()) {
				UserModel returnedUser = authenticateLocal(user, password);
				if (returnedUser != null) {
					// user authenticated
					return returnedUser;
				}
			} else {
				// try registered external authentication providers
				for (AuthenticationProvider provider : authenticationProviders) {
					if (provider instanceof UsernamePasswordAuthenticationProvider) {
						UserModel returnedUser = provider.authenticate(usernameDecoded, password);
						if (returnedUser != null) {
							// user authenticated
							returnedUser.accountType = provider.getAccountType();
							return validateAuthentication(returnedUser, AuthenticationType.CREDENTIALS);
						}
					}
				}
			}
		}
		finally {
			// Zero out password array to delete password from memory
			Arrays.fill(password, Character.MIN_VALUE);
		}

		// could not authenticate locally or with a provider
		logger.warn(MessageFormat.format("Failed login attempt for {0}, invalid credentials from {1}", username, 
				remoteIP != null ? remoteIP : "unknown"));
		
		return null;
	}

	/**
	 * Returns a UserModel if local authentication succeeds.
	 *
	 * @param user
	 * @param password
	 * @return a UserModel if local authentication succeeds, null otherwise
	 */
	protected UserModel authenticateLocal(UserModel user, char [] password) {
		UserModel returnedUser = null;

		// Create a copy of the password that we can use to rehash to upgrade to a more secure hashing method.
		// This is done to be independent from the implementation of the PasswordHash, which might already clear out
		// the password it gets passed in. This looks a bit stupid, as we could simply clean up the mess, but this
		// falls under "better safe than sorry".
		char[] pwdToUpgrade = Arrays.copyOf(password, password.length);
		try {
			PasswordHash pwdHash = PasswordHash.instanceFor(user.password);
			if (pwdHash != null) {
				if (pwdHash.matches(user.password, password, user.username)) {
					returnedUser = user;
				}
			} else if (user.password.equals(new String(password))) {
				// plain-text password
				returnedUser = user;
			}

			// validate user
			returnedUser = validateAuthentication(returnedUser, AuthenticationType.CREDENTIALS);

			// try to upgrade the stored password hash to a stronger hash, if necessary
			upgradeStoredPassword(returnedUser, pwdToUpgrade, pwdHash);
		}
		finally {
			// Now we make sure that the password is zeroed out in any case.
			Arrays.fill(password, Character.MIN_VALUE);
			Arrays.fill(pwdToUpgrade, Character.MIN_VALUE);
		}

		return returnedUser;
	}

	/**
	 * Upgrade stored password to a strong hash if configured.
	 *
	 * @param user the user to be updated
	 * @param password the password
	 * @param pwdHash
	 * 				Instance of PasswordHash for the stored password entry. If null, no current hashing is assumed.
	 */
	private void upgradeStoredPassword(UserModel user, char[] password, PasswordHash pwdHash) {
		// check if user has successfully authenticated i.e. is not null 
		if (user == null) return;

		// check if strong hash algorithm is configured
		String algorithm = settings.getString(Keys.realm.passwordStorage, PasswordHash.getDefaultType().name());
		if (pwdHash == null || pwdHash.needsUpgradeTo(algorithm)) {
			// rehash the provided correct password and update the user model
			pwdHash = PasswordHash.instanceOf(algorithm);
			if (pwdHash != null) { // necessary since the algorithm name could be something not supported.
				user.password = pwdHash.toHashedEntry(password, user.username);
				userManager.updateUserModel(user);
			}
		}
	}


	/**
	 * Returns the Gitlbit cookie in the request.
	 *
	 * @param request
	 * @return the Gitblit cookie for the request or null if not found
	 */
	@Override
	public String getCookie(HttpServletRequest request) {
		if (settings.getBoolean(Keys.web.allowCookieAuthentication, true)) {
			Cookie[] cookies = request.getCookies();
			if (cookies != null && cookies.length > 0) {
				for (Cookie cookie : cookies) {
					if (cookie.getName().equals(Constants.NAME)) {
						String value = cookie.getValue();
						return value;
					}
				}
			}
		}
		return null;
	}

	/**
	 * Sets a cookie for the specified user.
	 *
	 * @param response
	 * @param user
	 */
	@Override
	@Deprecated
	public void setCookie(HttpServletResponse response, UserModel user) {
		setCookie(null, response, user);
	}

	/**
	 * Sets a cookie for the specified user.
	 *
	 * @param request
	 * @param response
	 * @param user
	 */
	@Override
	public void setCookie(HttpServletRequest request, HttpServletResponse response, UserModel user) {
		if (settings.getBoolean(Keys.web.allowCookieAuthentication, true)) {
			boolean standardLogin = true;

			if (null != request) {
				// Pull the auth type from the request, it is set there if container managed
				AuthenticationType authenticationType = (AuthenticationType) request.getAttribute(Constants.ATTRIB_AUTHTYPE);

				if (null != authenticationType)
					standardLogin = authenticationType.isStandard();
			}

			if (standardLogin) {
				Cookie userCookie;
				if (user == null) {
					// clear cookie for logout
					userCookie = new Cookie(Constants.NAME, "");
				} else {
					// set cookie for login
					String cookie = userManager.getCookie(user);
					if (StringUtils.isEmpty(cookie)) {
						// create empty cookie
						userCookie = new Cookie(Constants.NAME, "");
					} else {
						// create real cookie
						userCookie = new Cookie(Constants.NAME, cookie);
						// expire the cookie in 7 days
						userCookie.setMaxAge((int) TimeUnit.DAYS.toSeconds(7));

						// Set cookies HttpOnly so they are not accessible to JavaScript engines
						userCookie.setHttpOnly(true);
						// Set secure cookie if only HTTPS is used
						userCookie.setSecure(httpsOnly());
					}
				}
				String path = "/";
				if (request != null) {
					if (!StringUtils.isEmpty(request.getContextPath())) {
						path = request.getContextPath();
					}
				}
				userCookie.setPath(path);
				response.addCookie(userCookie);
			}
		}
	}


	private boolean httpsOnly() {
		int port = settings.getInteger(Keys.server.httpPort, 0);
		int tlsPort = settings.getInteger(Keys.server.httpsPort, 0);
		return  (port <= 0 && tlsPort > 0) ||
				(port > 0 && tlsPort > 0 && settings.getBoolean(Keys.server.redirectToHttpsPort, true) );
	}


	/**
	 * Logout a user.
	 *
	 * @param response
	 * @param user
	 */
	@Override
	@Deprecated
	public void logout(HttpServletResponse response, UserModel user) {
		setCookie(null, response,  null);
	}

	/**
	 * Logout a user.
	 *
	 * @param request
	 * @param response
	 * @param user
	 */
	@Override
	public void logout(HttpServletRequest request, HttpServletResponse response, UserModel user) {
		setCookie(request, response,  null);
	}

	/**
	 * Returns true if the user's credentials can be changed.
	 *
	 * @param user
	 * @return true if the user service supports credential changes
	 */
	@Override
	public boolean supportsCredentialChanges(UserModel user) {
		return (user != null && user.isLocalAccount()) || findProvider(user).supportsCredentialChanges();
	}

	/**
	 * Returns true if the user's display name can be changed.
	 *
	 * @param user
	 * @return true if the user service supports display name changes
	 */
	@Override
	public boolean supportsDisplayNameChanges(UserModel user) {
		return (user != null && user.isLocalAccount()) || findProvider(user).supportsDisplayNameChanges();
	}

	/**
	 * Returns true if the user's email address can be changed.
	 *
	 * @param user
	 * @return true if the user service supports email address changes
	 */
	@Override
	public boolean supportsEmailAddressChanges(UserModel user) {
		return (user != null && user.isLocalAccount()) || findProvider(user).supportsEmailAddressChanges();
	}

	/**
	 * Returns true if the user's team memberships can be changed.
	 *
	 * @param user
	 * @return true if the user service supports team membership changes
	 */
	@Override
	public boolean supportsTeamMembershipChanges(UserModel user) {
		return (user != null && user.isLocalAccount()) || findProvider(user).supportsTeamMembershipChanges();
	}

	/**
	 * Returns true if the team memberships can be changed.
	 *
	 * @param user
	 * @return true if the team membership can be changed
	 */
	@Override
	public boolean supportsTeamMembershipChanges(TeamModel team) {
		return (team != null && team.isLocalTeam()) || findProvider(team).supportsTeamMembershipChanges();
	}

	/**
	 * Returns true if the user's role can be changed.
	 *
	 * @param user
	 * @return true if the user's role can be changed
	 */
	@Override
	public boolean supportsRoleChanges(UserModel user, Role role) {
		return (user != null && user.isLocalAccount()) || findProvider(user).supportsRoleChanges(user, role);
	}

	/**
	 * Returns true if the team's role can be changed.
	 *
	 * @param user
	 * @return true if the team's role can be changed
	 */
	@Override
	public boolean supportsRoleChanges(TeamModel team, Role role) {
		return (team != null && team.isLocalTeam()) || findProvider(team).supportsRoleChanges(team, role);
	}

	protected AuthenticationProvider findProvider(UserModel user) {
		for (AuthenticationProvider provider : authenticationProviders) {
			if (provider.getAccountType().equals(user.accountType)) {
				return provider;
			}
		}
		return AuthenticationProvider.NULL_PROVIDER;
	}

	protected AuthenticationProvider findProvider(TeamModel team) {
		for (AuthenticationProvider provider : authenticationProviders) {
			if (provider.getAccountType().equals(team.accountType)) {
				return provider;
			}
		}
		return AuthenticationProvider.NULL_PROVIDER;
	}
}