Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.hadoop.security.alias; import java.io.Console; import java.io.IOException; import java.security.InvalidParameterException; import java.security.NoSuchAlgorithmException; import java.util.Arrays; import java.util.List; import com.google.common.annotations.VisibleForTesting; import org.apache.commons.lang3.StringUtils; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.tools.CommandShell; import org.apache.hadoop.util.ToolRunner; /** * This program is the CLI utility for the CredentialProvider facilities in * Hadoop. */ public class CredentialShell extends CommandShell { final static private String USAGE_PREFIX = "Usage: hadoop credential " + "[generic options]\n"; final static private String COMMANDS = " [-help]\n" + " [" + CreateCommand.USAGE + "]\n" + " [" + DeleteCommand.USAGE + "]\n" + " [" + ListCommand.USAGE + "]\n"; @VisibleForTesting public static final String NO_VALID_PROVIDERS = "There are no valid (non-transient) providers configured.\n" + "No action has been taken. Use the -provider option to specify\n" + "a provider. If you want to use a transient provider then you\n" + "MUST use the -provider argument."; private boolean interactive = true; /** If true, fail if the provider requires a password and none is given. */ private boolean strict = false; private boolean userSuppliedProvider = false; private String value = null; private PasswordReader passwordReader; /** * Parse the command line arguments and initialize the data. * <pre> * % hadoop credential create alias [-provider providerPath] * % hadoop credential list [-provider providerPath] * % hadoop credential delete alias [-provider providerPath] [-f] * </pre> * @param args * @return 0 if the argument(s) were recognized, 1 otherwise * @throws IOException */ @Override protected int init(String[] args) throws IOException { // no args should print the help message if (0 == args.length) { ToolRunner.printGenericCommandUsage(getErr()); return 1; } for (int i = 0; i < args.length; i++) { // parse command line if (args[i].equals("create")) { if (i == args.length - 1) { return 1; } setSubCommand(new CreateCommand(args[++i])); } else if (args[i].equals("delete")) { if (i == args.length - 1) { return 1; } setSubCommand(new DeleteCommand(args[++i])); } else if (args[i].equals("list")) { setSubCommand(new ListCommand()); } else if (args[i].equals("-provider")) { if (i == args.length - 1) { return 1; } userSuppliedProvider = true; getConf().set(CredentialProviderFactory.CREDENTIAL_PROVIDER_PATH, args[++i]); } else if (args[i].equals("-f") || (args[i].equals("-force"))) { interactive = false; } else if (args[i].equals("-strict")) { strict = true; } else if (args[i].equals("-v") || (args[i].equals("-value"))) { value = args[++i]; } else if (args[i].equals("-help")) { printShellUsage(); return 0; } else { ToolRunner.printGenericCommandUsage(getErr()); return 1; } } return 0; } @Override public String getCommandUsage() { StringBuffer sbuf = new StringBuffer(USAGE_PREFIX + COMMANDS); String banner = StringUtils.repeat("=", 66); sbuf.append(banner + "\n"); sbuf.append(CreateCommand.USAGE + ":\n\n" + CreateCommand.DESC + "\n"); sbuf.append(banner + "\n"); sbuf.append(DeleteCommand.USAGE + ":\n\n" + DeleteCommand.DESC + "\n"); sbuf.append(banner + "\n"); sbuf.append(ListCommand.USAGE + ":\n\n" + ListCommand.DESC + "\n"); return sbuf.toString(); } private abstract class Command extends SubCommand { protected CredentialProvider provider = null; protected CredentialProvider getCredentialProvider() { CredentialProvider prov = null; List<CredentialProvider> providers; try { providers = CredentialProviderFactory.getProviders(getConf()); if (userSuppliedProvider) { prov = providers.get(0); } else { for (CredentialProvider p : providers) { if (!p.isTransient()) { prov = p; break; } } } } catch (IOException e) { e.printStackTrace(getErr()); } if (prov == null) { getOut().println(NO_VALID_PROVIDERS); } return prov; } protected void printProviderWritten() { getOut().println("Provider " + provider.toString() + " was updated."); } protected void warnIfTransientProvider() { if (provider.isTransient()) { getOut().println("WARNING: you are modifying a transient provider."); } } protected void doHelp() { getOut().println(USAGE_PREFIX + COMMANDS); printShellUsage(); } public abstract void execute() throws Exception; public abstract String getUsage(); } private class ListCommand extends Command { public static final String USAGE = "list [-provider provider-path] [-strict]"; public static final String DESC = "The list subcommand displays the aliases contained within \n" + "a particular provider - as configured in core-site.xml or\n" + "indicated through the -provider argument. If -strict is supplied,\n" + "fail immediately if the provider requires a password and none is\n" + "provided."; public boolean validate() { provider = getCredentialProvider(); return (provider != null); } public void execute() throws IOException { List<String> aliases; try { aliases = provider.getAliases(); getOut().println("Listing aliases for CredentialProvider: " + provider.toString()); for (String alias : aliases) { getOut().println(alias); } } catch (IOException e) { getOut().println("Cannot list aliases for CredentialProvider: " + provider.toString() + ": " + e.getMessage()); throw e; } } @Override public String getUsage() { return USAGE + ":\n\n" + DESC; } } private class DeleteCommand extends Command { public static final String USAGE = "delete <alias> [-f] [-provider provider-path] [-strict]"; public static final String DESC = "The delete subcommand deletes the credential\n" + "specified as the <alias> argument from within the provider\n" + "indicated through the -provider argument. The command asks for\n" + "confirmation unless the -f option is specified. If -strict is\n" + "supplied, fail immediately if the provider requires a password\n" + "and none is given."; private String alias = null; private boolean cont = true; public DeleteCommand(String alias) { this.alias = alias; } @Override public boolean validate() { if (alias == null) { getOut().println("There is no alias specified. Please provide the" + "mandatory <alias>. See the usage description with -help."); return false; } if (alias.equals("-help")) { return true; } provider = getCredentialProvider(); if (provider == null) { return false; } if (interactive) { try { cont = ToolRunner.confirmPrompt("You are about to DELETE the credential " + alias + " from CredentialProvider " + provider.toString() + ". Continue? "); if (!cont) { getOut().println("Nothing has been deleted."); } return cont; } catch (IOException e) { getOut().println(alias + " will not be deleted."); e.printStackTrace(getErr()); } } return true; } public void execute() throws IOException { if (alias.equals("-help")) { doHelp(); return; } warnIfTransientProvider(); getOut().println("Deleting credential: " + alias + " from CredentialProvider: " + provider.toString()); if (cont) { try { provider.deleteCredentialEntry(alias); getOut().println("Credential " + alias + " has been successfully deleted."); provider.flush(); printProviderWritten(); } catch (IOException e) { getOut().println("Credential " + alias + " has NOT been deleted."); throw e; } } } @Override public String getUsage() { return USAGE + ":\n\n" + DESC; } } private class CreateCommand extends Command { public static final String USAGE = "create <alias> [-value alias-value] " + "[-provider provider-path] [-strict]"; public static final String DESC = "The create subcommand creates a new credential for the name\n" + "specified as the <alias> argument within the provider indicated\n" + "through the -provider argument. If -strict is supplied, fail\n" + "immediately if the provider requires a password and none is given.\n" + "If -value is provided, use that for the value of the credential\n" + "instead of prompting the user."; private String alias = null; public CreateCommand(String alias) { this.alias = alias; } public boolean validate() { if (alias == null) { getOut().println("There is no alias specified. Please provide the" + "mandatory <alias>. See the usage description with -help."); return false; } if (alias.equals("-help")) { return true; } try { provider = getCredentialProvider(); if (provider == null) { return false; } else if (provider.needsPassword()) { if (strict) { getOut().println(provider.noPasswordError()); return false; } else { getOut().println(provider.noPasswordWarning()); } } } catch (IOException e) { e.printStackTrace(getErr()); } return true; } public void execute() throws IOException, NoSuchAlgorithmException { if (alias.equals("-help")) { doHelp(); return; } warnIfTransientProvider(); try { char[] credential = null; if (value != null) { // testing only credential = value.toCharArray(); } else { credential = promptForCredential(); } provider.createCredentialEntry(alias, credential); provider.flush(); getOut().println(alias + " has been successfully created."); printProviderWritten(); } catch (InvalidParameterException e) { getOut().println("Credential " + alias + " has NOT been created. " + e.getMessage()); throw e; } catch (IOException e) { getOut().println("Credential " + alias + " has NOT been created. " + e.getMessage()); throw e; } } @Override public String getUsage() { return USAGE + ":\n\n" + DESC; } } protected char[] promptForCredential() throws IOException { PasswordReader c = getPasswordReader(); if (c == null) { throw new IOException("No console available for prompting user."); } char[] cred = null; boolean noMatch; do { char[] newPassword1 = c.readPassword("Enter alias password: "); char[] newPassword2 = c.readPassword("Enter alias password again: "); noMatch = !Arrays.equals(newPassword1, newPassword2); if (noMatch) { if (newPassword1 != null) { Arrays.fill(newPassword1, ' '); } c.format("Passwords don't match. Try again.%n"); } else { cred = newPassword1; } if (newPassword2 != null) { Arrays.fill(newPassword2, ' '); } } while (noMatch); return cred; } public PasswordReader getPasswordReader() { if (passwordReader == null) { passwordReader = new PasswordReader(); } return passwordReader; } public void setPasswordReader(PasswordReader reader) { passwordReader = reader; } /** To facilitate testing since Console is a final class. */ public static class PasswordReader { public char[] readPassword(String prompt) { Console console = System.console(); char[] pass = console.readPassword(prompt); return pass; } public void format(String message) { Console console = System.console(); console.format(message); } } /** * Main program. * * @param args * Command line arguments * @throws Exception */ public static void main(String[] args) throws Exception { int res = ToolRunner.run(new Configuration(), new CredentialShell(), args); System.exit(res); } }