// Copyright (C) 2001-2003, 2011, 2022 VeriSign, Inc.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA

package com.verisignlabs.dnssec.cl;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileFilter;
import java.io.FileReader;
import java.io.IOException;
import java.time.Instant;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Random;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;
import org.xbill.DNS.DNSKEYRecord;
import org.xbill.DNS.DNSSEC;
import org.xbill.DNS.Name;
import org.xbill.DNS.RRset;
import org.xbill.DNS.Record;
import org.xbill.DNS.TextParseException;
import org.xbill.DNS.Type;
import org.xbill.DNS.utils.base16;

import com.verisignlabs.dnssec.security.BINDKeyUtils;
import com.verisignlabs.dnssec.security.DnsKeyPair;
import com.verisignlabs.dnssec.security.DnsSecVerifier;
import com.verisignlabs.dnssec.security.JCEDnsSecSigner;
import com.verisignlabs.dnssec.security.SignUtils;
import com.verisignlabs.dnssec.security.ZoneUtils;

/**
 * This class forms the command line implementation of a DNSSEC zone signer.
 *
 * @author David Blacka
 */
public class SignZone extends CLBase {
  private CLIState state;

  /**
   * This is an inner class used to hold all of the command line option state.
   */
  private static class CLIState extends CLIStateBase {
    public File keyDirectory = null;
    public File keysetDirectory = null;
    public String[] kskFiles = null;
    public String[] keyFiles = null;
    public String zonefile = null;
    public Instant start = null;
    public Instant expire = null;
    public String outputfile = null;
    public boolean verifySigs = false;
    public boolean useOptOut = false;
    public boolean fullySignKeyset = false;
    public List<Name> includeNames = null;
    public boolean useNsec3 = false;
    public byte[] salt = null;
    public int iterations = 0;
    public int digestId = DNSSEC.Digest.SHA1;
    public long nsec3paramttl = -1;
    public boolean verboseSigning = false;

    public CLIState() {
      super("jdnssec-signzone [..options..] zone_file [key_file ...]");
    }

    @Override
    protected void setupOptions(Options opts) {
      // boolean options
      opts.addOption("a", "verify", false, "verify generated signatures>");
      opts.addOption("F", "fully-sign-keyset", false,
          "sign the zone apex keyset with all available keys.");
      opts.addOption("V", "verbose-signing", false, "Display verbose signing activity.");

      opts.addOption(Option.builder("d").hasArg().argName("dir").longOpt("keyset-directory")
          .desc("directory to find keyset files (default '.')").build());
      opts.addOption(Option.builder("D").hasArg().argName("dir").longOpt("key-directory")
          .desc("directory to find key files (default '.'").build());
      opts.addOption(Option.builder("s").hasArg().argName("time/offset").longOpt("start-time")
          .desc("signature starting time (default is now - 1 hour)").build());
      opts.addOption(Option.builder("e").hasArg().argName("time/offset").longOpt("expire-time")
          .desc("signature expiration time (default is start-time + 30 days)").build());
      opts.addOption(
          Option.builder("f").hasArg().argName("outfile").desc("file the the signed rrset is written to").build());
      opts.addOption(Option.builder("k").hasArgs().argName("KSK file").longOpt("ksk-file")
          .desc("This key is a Key-Signing Key (may repeat)").build());
      opts.addOption(Option.builder("I").hasArg().argName("file").longOpt("include-file")
          .desc("include names in the file in the NSEC/NSEC3 chain").build());

      // NSEC3 options
      opts.addOption("3", "use-nsec3", false, "use NSEC3 instead of NSEC");
      opts.addOption("O", "use-opt-out", false,
          "generate a fully Opt-Out zone (only valid with NSEC3).");
      opts.addOption(
          Option.builder("S").hasArg().argName("hex value").longOpt("salt").desc("Supply a salt value").build());
      opts.addOption(Option.builder("R").hasArg().argName("length").longOpt("random-salt")
          .desc("Generate a random salt of <length>").build());
      opts.addOption(Option.builder("H").hasArg().argName("count").longOpt("iterations")
          .desc("Use this many addtional iterations in NSEC3 (default 0)").build());
      opts.addOption(Option.builder().hasArg().longOpt("nsec3paramttl").argName("ttl")
          .desc("Use this TTL for the NSEC3PARAM record (default is min(soa.min, soa.ttl))").build());
      opts.addOption(Option.builder().hasArg().argName("id").longOpt("ds-digest")
          .desc("Digest algorithm to use for generated DS records").build());

    }

    @Override
    protected void processOptions(CommandLine cli) throws ParseException {
      String optstr = null;

      if (cli.hasOption('a'))
        verifySigs = true;
      if (cli.hasOption('3'))
        useNsec3 = true;
      if (cli.hasOption('O'))
        useOptOut = true;
      if (cli.hasOption('V'))
        verboseSigning = true;

      if (useOptOut && !useNsec3) {
        System.err.println("Opt-Out not supported without NSEC3 -- ignored.");
        useOptOut = false;
      }

      if (cli.hasOption('F'))
        fullySignKeyset = true;

      if ((optstr = cli.getOptionValue('d')) != null) {
        keysetDirectory = new File(optstr);
        if (!keysetDirectory.isDirectory()) {
          System.err.println("error: " + optstr + " is not a directory");
          usage();

        }
      }

      if ((optstr = cli.getOptionValue('D')) != null) {
        keyDirectory = new File(optstr);
        if (!keyDirectory.isDirectory()) {
          System.err.println("error: " + optstr + " is not a directory");
          usage();
        }
      }

      if ((optstr = cli.getOptionValue('s')) != null) {
        start = CLBase.convertDuration(null, optstr);
      } else {
        // default is now - 1 hour.
        start = Instant.now().minusSeconds(3600);
      }

      if ((optstr = cli.getOptionValue('e')) != null) {
        expire = CLBase.convertDuration(start, optstr);
      } else {
        expire = CLBase.convertDuration(start, "+2592000"); // 30 days
      }

      outputfile = cli.getOptionValue('f');

      kskFiles = cli.getOptionValues('k');

      if ((optstr = cli.getOptionValue('I')) != null) {
        File includeNamesFile = new File(optstr);
        try {
          includeNames = CLIState.getNameList(includeNamesFile);
        } catch (IOException e) {
          throw new ParseException(e.getMessage());
        }
      }

      if ((optstr = cli.getOptionValue('S')) != null) {
        salt = base16.fromString(optstr);
        if (salt == null && !optstr.equals("-")) {
          System.err.println("error: salt is not valid hexidecimal.");
          usage();
        }
      }

      if ((optstr = cli.getOptionValue('R')) != null) {
        int length = parseInt(optstr, 0);
        if (length > 0 && length <= 255) {
          Random random = new Random();
          salt = new byte[length];
          random.nextBytes(salt);
        }
      }

      if ((optstr = cli.getOptionValue("iterations")) != null) {
        iterations = parseInt(optstr, iterations);
        if (iterations < 0 || iterations > 8388607) {
          System.err.println("error: iterations value is invalid");
          usage();
        }
      }

      if ((optstr = cli.getOptionValue("ds-digest")) != null) {
        digestId = parseInt(optstr, -1);
        if (digestId < 0) {
          System.err.println("error: DS digest ID is not a valid identifier");
          usage();
        }
      }

      if ((optstr = cli.getOptionValue("nsec3paramttl")) != null) {
        nsec3paramttl = parseInt(optstr, -1);
      }

      String[] files = cli.getArgs();

      if (files.length < 1) {
        System.err.println("error: missing zone file and/or key files");
        usage();
      }

      zonefile = files[0];
      if (files.length > 1) {
        keyFiles = new String[files.length - 1];
        System.arraycopy(files, 1, keyFiles, 0, files.length - 1);
      }
    }

    /**
     * Load a list of DNS names from a file.
     *
     * @param nameListFile
     *                     the path of a file containing a bare list of DNS names.
     * @return a list of {@link org.xbill.DNS.Name} objects.
     */
    private static List<Name> getNameList(File nameListFile) throws IOException {
      try (BufferedReader br = new BufferedReader(new FileReader(nameListFile))) {
        List<Name> res = new ArrayList<>();

        String line = null;
        while ((line = br.readLine()) != null) {
          try {
            Name n = Name.fromString(line);
            // force the name to be absolute.
            // FIXME: we should probably get some fancy logic here to
            // detect if the name needs the origin appended, or just the
            // root.
            if (!n.isAbsolute())
              n = Name.concatenate(n, Name.root);

            res.add(n);
          } catch (TextParseException e) {
            staticLog.severe("DNS Name parsing error:" + e);
          }
        }

        return res;
      }
    }
  }

  /**
   * Verify the generated signatures.
   *
   * @param records
   *                 a list of {@link org.xbill.DNS.Record}s.
   * @param keypairs
   *                 a list of keypairs used the sign the zone.
   * @return true if all of the signatures validated.
   */
  private static boolean verifyZoneSigs(List<Record> records,
      List<DnsKeyPair> keypairs) {
    boolean secure = true;

    DnsSecVerifier verifier = new DnsSecVerifier();

    for (DnsKeyPair pair : keypairs) {
      verifier.addTrustedKey(pair);
    }

    verifier.setVerifyAllSigs(true);

    List<RRset> rrsets = SignUtils.assembleIntoRRsets(records);

    for (RRset rrset : rrsets) {
      // skip unsigned rrsets.
      if (rrset.sigs().isEmpty()) {
        continue;
      }

      boolean result = verifier.verify(rrset);

      if (!result) {
        staticLog.fine("Signatures did not verify for RRset: " + rrset);
        secure = false;
      }
    }

    return secure;
  }

  /**
   * Load the key pairs from the key files.
   *
   * @param keyfiles
   *                    a string array containing the base names or paths of the
   *                    keys to
   *                    be loaded.
   * @param startIndex
   *                    the starting index of keyfiles string array to use. This
   *                    allows
   *                    us
   *                    to use the straight command line argument array.
   * @param inDirectory
   *                    the directory to look in (may be null).
   * @return a list of keypair objects.
   */
  private static List<DnsKeyPair> getKeys(String[] keyfiles, int startIndex,
      File inDirectory) throws IOException {
    if (keyfiles == null)
      return Collections.emptyList();

    int len = keyfiles.length - startIndex;
    if (len <= 0)
      return Collections.emptyList();

    ArrayList<DnsKeyPair> keys = new ArrayList<>(len);

    for (int i = startIndex; i < keyfiles.length; i++) {
      DnsKeyPair k = BINDKeyUtils.loadKeyPair(keyfiles[i], inDirectory);
      if (k != null) {
        keys.add(k);
      }
    }

    return keys;
  }

  private static List<DnsKeyPair> getKeys(List<Record> dnskeyrrs, File inDirectory)
      throws IOException {
    List<DnsKeyPair> res = new ArrayList<>();
    for (Record r : dnskeyrrs) {
      if (r.getType() != Type.DNSKEY)
        continue;

      // Construct a public-key-only DnsKeyPair just so we can calculate the
      // base name.
      DnsKeyPair pub = new DnsKeyPair((DNSKEYRecord) r);
      DnsKeyPair pair = BINDKeyUtils.loadKeyPair(BINDKeyUtils.keyFileBase(pub),
          inDirectory);
      if (pair != null) {
        res.add(pair);
      }
    }
    return res;
  }

  private static class KeyFileFilter implements FileFilter {
    private String prefix;

    public KeyFileFilter(Name origin) {
      prefix = "K" + origin.toString();
    }

    public boolean accept(File pathname) {
      if (!pathname.isFile())
        return false;
      String name = pathname.getName();
      return (name.startsWith(prefix) && name.endsWith(".private"));
    }
  }

  private static List<DnsKeyPair> findZoneKeys(File inDirectory, Name zonename)
      throws IOException {
    if (inDirectory == null) {
      inDirectory = new File(".");
    }

    // get the list of "K<zone>.*.private files.
    FileFilter filter = new KeyFileFilter(zonename);
    File[] files = inDirectory.listFiles(filter);

    // read in all of the records
    ArrayList<DnsKeyPair> keys = new ArrayList<>();
    for (int i = 0; i < files.length; i++) {
      DnsKeyPair p = BINDKeyUtils.loadKeyPair(files[i].getName(), inDirectory);
      keys.add(p);
    }

    return keys;
  }

  /**
   * This is an implementation of a file filter used for finding BIND 9-style
   * keyset-* files.
   */
  private static class KeysetFileFilter implements FileFilter {
    public boolean accept(File pathname) {
      if (!pathname.isFile())
        return false;
      String name = pathname.getName();
      return (name.startsWith("keyset-"));
    }
  }

  /**
   * Load keysets (which contain delegation point security info).
   *
   * @param inDirectory
   *                    the directory to look for the keyset files (may be null,
   *                    in
   *                    which
   *                    case it defaults to looking in the current working
   *                    directory).
   * @param zonename
   *                    the name of the zone we are signing, so we can ignore
   *                    keysets
   *                    that
   *                    do not belong in the zone.
   * @return a list of {@link org.xbill.DNS.Record}s found in the keyset
   *         files.
   */
  private static List<Record> getKeysets(File inDirectory, Name zonename)
      throws IOException {
    if (inDirectory == null) {
      inDirectory = new File(".");
    }

    // get the list of "keyset-" files.
    FileFilter filter = new KeysetFileFilter();
    File[] files = inDirectory.listFiles(filter);

    // read in all of the records
    ArrayList<Record> keysetRecords = new ArrayList<>();
    for (int i = 0; i < files.length; i++) {
      List<Record> l = ZoneUtils.readZoneFile(files[i].getAbsolutePath(), zonename);
      keysetRecords.addAll(l);
    }

    // discard records that do not belong to the zone in question.
    for (Iterator<Record> i = keysetRecords.iterator(); i.hasNext();) {
      Record r = i.next();
      if (!r.getName().subdomain(zonename)) {
        i.remove();
      }
    }

    return keysetRecords;
  }

  /**
   * Determine if the given keypairs can be used to sign the zone.
   *
   * @param zonename
   *                 the zone origin.
   * @param keypairs
   *                 a list of {@link DnsKeyPair} objects that will be used to
   *                 sign
   *                 the
   *                 zone.
   * @return true if the keypairs valid.
   */
  private static boolean keyPairsValidForZone(Name zonename, List<DnsKeyPair> keypairs) {
    if (keypairs == null)
      return true; // technically true, I guess.

    for (DnsKeyPair kp : keypairs) {
      Name keyname = kp.getDNSKEYRecord().getName();
      if (!keyname.equals(zonename)) {
        return false;
      }
    }

    return true;
  }

  public void execute() throws Exception {
    // Read in the zone
    List<Record> records = ZoneUtils.readZoneFile(state.zonefile, null);
    if (records == null || records.isEmpty()) {
      System.err.println("error: empty zone file");
      state.usage();
      return;
    }

    // calculate the zone name.
    Name zonename = ZoneUtils.findZoneName(records);
    if (zonename == null) {
      System.err.println("error: invalid zone file - no SOA");
      state.usage();
      return;
    }

    // Load the key pairs.

    List<DnsKeyPair> keypairs = getKeys(state.keyFiles, 0, state.keyDirectory);
    List<DnsKeyPair> kskpairs = getKeys(state.kskFiles, 0, state.keyDirectory);

    // If we didn't get any keys on the command line, look at the zone apex for
    // any public keys.
    if (keypairs == null && kskpairs == null) {
      List<Record> dnskeys = ZoneUtils.findRRs(records, zonename, Type.DNSKEY);
      keypairs = getKeys(dnskeys, state.keyDirectory);
    }

    // If we *still* don't have any key pairs, look for keys the key directory
    // that match
    if (keypairs == null && kskpairs == null) {
      keypairs = findZoneKeys(state.keyDirectory, zonename);
    }

    // If we don't have any KSKs, but we do have more than one zone
    // signing key (presumably), presume that the zone signing keys
    // are just not differentiated and try to figure out which keys
    // are actually ksks by looking at the SEP flag.
    if ((kskpairs == null || kskpairs.isEmpty()) && keypairs != null
        && keypairs.size() > 1) {
      for (Iterator<DnsKeyPair> i = keypairs.iterator(); i.hasNext();) {
        DnsKeyPair pair = i.next();
        DNSKEYRecord kr = pair.getDNSKEYRecord();
        if ((kr.getFlags() & DNSKEYRecord.Flags.SEP_KEY) != 0) {
          if (kskpairs == null)
            kskpairs = new ArrayList<>();
          kskpairs.add(pair);
          i.remove();
        }
      }
    }

    // If there are no ZSKs defined at this point (yet there are KSKs
    // provided), all KSKs will be treated as ZSKs, as well.
    if (keypairs == null || keypairs.isEmpty()) {
      keypairs = kskpairs;
    }

    // If there *still* aren't any ZSKs defined, bail.
    if (keypairs == null || keypairs.isEmpty()) {
      System.err.println("No zone signing keys could be determined.");
      state.usage();
      return;
    }

    // default the output file, if not set.
    if (state.outputfile == null && !state.zonefile.equals("-")) {
      if (zonename.isAbsolute()) {
        state.outputfile = zonename + "signed";
      } else {
        state.outputfile = zonename + ".signed";
      }
    }

    // Verify that the keys can be in the zone.
    if (!keyPairsValidForZone(zonename, keypairs)
        || !keyPairsValidForZone(zonename, kskpairs)) {
      System.err.println("error: specified keypairs are not valid for the zone.");
      state.usage();
    }

    // We force the signing keys to be in the zone by just appending
    // them to the zone here. Currently JCEDnsSecSigner.signZone
    // removes duplicate records.
    if (kskpairs != null) {
      for (DnsKeyPair pair : kskpairs) {
        records.add(pair.getDNSKEYRecord());
      }
    }
    if (keypairs != null) {
      for (DnsKeyPair pair : keypairs) {
        records.add(pair.getDNSKEYRecord());
      }
    }

    // read in the keysets, if any.
    List<Record> keysetrecs = getKeysets(state.keysetDirectory, zonename);
    if (keysetrecs != null) {
      records.addAll(keysetrecs);
    }

    JCEDnsSecSigner signer = new JCEDnsSecSigner(state.verboseSigning);

    // Sign the zone.
    List<Record> signedRecords;

    if (state.useNsec3) {
      signedRecords = signer.signZoneNSEC3(zonename, records, kskpairs, keypairs,
          state.start, state.expire,
          state.fullySignKeyset, state.useOptOut,
          state.includeNames, state.salt,
          state.iterations, state.digestId,
          state.nsec3paramttl);
    } else {
      signedRecords = signer.signZone(zonename, records, kskpairs, keypairs,
          state.start, state.expire, state.fullySignKeyset,
          state.digestId);
    }

    // write out the signed zone
    ZoneUtils.writeZoneFile(signedRecords, state.outputfile);

    if (state.verifySigs) {
      // FIXME: ugh.
      if (kskpairs != null) {
        keypairs.addAll(kskpairs);
      }

      log.fine("verifying generated signatures");
      boolean res = verifyZoneSigs(signedRecords, keypairs);

      if (res) {
        System.out.println("Generated signatures verified");
      } else {
        System.out.println("Generated signatures did not verify.");
      }
    }

  }

  public static void main(String[] args) {
    SignZone tool = new SignZone();
    tool.state = new CLIState();

    tool.run(tool.state, args);
  }
}