directory.js

var binary = require('binary');
var PullStream = require('../PullStream');
var unzip = require('./unzip');
var Promise = require('bluebird');
var BufferStream = require('../BufferStream');
var parseExtraField = require('../parseExtraField');
var Buffer = require('../Buffer');
var path = require('path');
var Writer = require('fstream').Writer;
var parseDateTime = require('../parseDateTime');

var signature = Buffer.alloc(4);
signature.writeUInt32LE(0x06054b50,0);

function getCrxHeader(source) {
  var sourceStream = source.stream(0).pipe(PullStream());

  return sourceStream.pull(4).then(function(data) {
    var signature = data.readUInt32LE(0);
    if (signature === 0x34327243) {
      var crxHeader;
      return sourceStream.pull(12).then(function(data) {
        crxHeader = binary.parse(data)
          .word32lu('version')
          .word32lu('pubKeyLength')
          .word32lu('signatureLength')
          .vars;
      }).then(function() {
        return sourceStream.pull(crxHeader.pubKeyLength +crxHeader.signatureLength);
      }).then(function(data) {
        crxHeader.publicKey = data.slice(0,crxHeader.pubKeyLength);
        crxHeader.signature = data.slice(crxHeader.pubKeyLength);
        crxHeader.size = 16 + crxHeader.pubKeyLength +crxHeader.signatureLength;
        return crxHeader;
      });
    }
  });
}

// Zip64 File Format Notes: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
function getZip64CentralDirectory(source, zip64CDL) {
  var d64loc = binary.parse(zip64CDL)
    .word32lu('signature')
    .word32lu('diskNumber')
    .word64lu('offsetToStartOfCentralDirectory')
    .word32lu('numberOfDisks')
    .vars;

  if (d64loc.signature != 0x07064b50) {
    throw new Error('invalid zip64 end of central dir locator signature (0x07064b50): 0x' + d64loc.signature.toString(16));
  }

  var dir64 = PullStream();
  source.stream(d64loc.offsetToStartOfCentralDirectory).pipe(dir64);

  return dir64.pull(56)
}

// Zip64 File Format Notes: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
function parseZip64DirRecord (dir64record) {
  var vars = binary.parse(dir64record)
    .word32lu('signature')
    .word64lu('sizeOfCentralDirectory')
    .word16lu('version')
    .word16lu('versionsNeededToExtract')
    .word32lu('diskNumber')
    .word32lu('diskStart')
    .word64lu('numberOfRecordsOnDisk')
    .word64lu('numberOfRecords')
    .word64lu('sizeOfCentralDirectory')
    .word64lu('offsetToStartOfCentralDirectory')
    .vars;

  if (vars.signature != 0x06064b50) {
    throw new Error('invalid zip64 end of central dir locator signature (0x06064b50): 0x0' + vars.signature.toString(16));
  }

  return vars
}

module.exports = function centralDirectory(source, options) {
  var endDir = PullStream(),
      records = PullStream(),
      tailSize = (options && options.tailSize) || 80,
      sourceSize,
      crxHeader,
      startOffset,
      vars;

  if (options && options.crx)
    crxHeader = getCrxHeader(source);

  return source.size()
    .then(function(size) {
      sourceSize = size;

      source.stream(Math.max(0,size-tailSize))
        .on('error', function (error) { endDir.emit('error', error) })
        .pipe(endDir);

      return endDir.pull(signature);
    })
    .then(function() {
      return Promise.props({directory: endDir.pull(22), crxHeader: crxHeader});
    })
    .then(function(d) {
      var data = d.directory;
      startOffset = d.crxHeader && d.crxHeader.size || 0;

      vars = binary.parse(data)
        .word32lu('signature')
        .word16lu('diskNumber')
        .word16lu('diskStart')
        .word16lu('numberOfRecordsOnDisk')
        .word16lu('numberOfRecords')
        .word32lu('sizeOfCentralDirectory')
        .word32lu('offsetToStartOfCentralDirectory')
        .word16lu('commentLength')
        .vars;

      // Is this zip file using zip64 format? Use same check as Go:
      // https://github.com/golang/go/blob/master/src/archive/zip/reader.go#L503
      // For zip64 files, need to find zip64 central directory locator header to extract
      // relative offset for zip64 central directory record.
      if (vars.numberOfRecords == 0xffff|| vars.numberOfRecords == 0xffff ||
        vars.offsetToStartOfCentralDirectory == 0xffffffff) {

        // Offset to zip64 CDL is 20 bytes before normal CDR
        const zip64CDLSize = 20
        const zip64CDLOffset = sourceSize - (tailSize - endDir.match + zip64CDLSize)
        const zip64CDLStream = PullStream();

        source.stream(zip64CDLOffset).pipe(zip64CDLStream);

        return zip64CDLStream.pull(zip64CDLSize)
          .then(function (d) { return getZip64CentralDirectory(source, d) })
          .then(function (dir64record) {
            vars = parseZip64DirRecord(dir64record)
          })
      } else {
        vars.offsetToStartOfCentralDirectory += startOffset;
      }
    })
    .then(function() {
      if (vars.commentLength) return endDir.pull(vars.commentLength).then(function(comment) {
        vars.comment = comment.toString('utf8');
      });
    })
    .then(function() {
      source.stream(vars.offsetToStartOfCentralDirectory).pipe(records);

      vars.extract = function(opts) {
        if (!opts || !opts.path) throw new Error('PATH_MISSING');
        // make sure path is normalized before using it
        opts.path = path.resolve(path.normalize(opts.path));
        return vars.files.then(function(files) {
          return Promise.map(files, function(entry) {
            if (entry.type == 'Directory') return;

            // to avoid zip slip (writing outside of the destination), we resolve
            // the target path, and make sure it's nested in the intended
            // destination, or not extract it otherwise.
            var extractPath = path.join(opts.path, entry.path);
            if (extractPath.indexOf(opts.path) != 0) {
              return;
            }
            var writer = opts.getWriter ? opts.getWriter({path: extractPath}) :  Writer({ path: extractPath });

            return new Promise(function(resolve, reject) {
              entry.stream(opts.password)
                .on('error',reject)
                .pipe(writer)
                .on('close',resolve)
                .on('error',reject);
            });
          }, { concurrency: opts.concurrency > 1 ? opts.concurrency : 1 });
        });
      };

      vars.files = Promise.mapSeries(Array(vars.numberOfRecords),function() {
        return records.pull(46).then(function(data) {    
          var vars = binary.parse(data)
            .word32lu('signature')
            .word16lu('versionMadeBy')
            .word16lu('versionsNeededToExtract')
            .word16lu('flags')
            .word16lu('compressionMethod')
            .word16lu('lastModifiedTime')
            .word16lu('lastModifiedDate')
            .word32lu('crc32')
            .word32lu('compressedSize')
            .word32lu('uncompressedSize')
            .word16lu('fileNameLength')
            .word16lu('extraFieldLength')
            .word16lu('fileCommentLength')
            .word16lu('diskNumber')
            .word16lu('internalFileAttributes')
            .word32lu('externalFileAttributes')
            .word32lu('offsetToLocalFileHeader')
            .vars;

        vars.offsetToLocalFileHeader += startOffset;
        vars.lastModifiedDateTime = parseDateTime(vars.lastModifiedDate, vars.lastModifiedTime);

        return records.pull(vars.fileNameLength).then(function(fileNameBuffer) {
          vars.pathBuffer = fileNameBuffer;
          vars.path = fileNameBuffer.toString('utf8');
          vars.isUnicode = (vars.flags & 0x800) != 0;
          return records.pull(vars.extraFieldLength);
        })
        .then(function(extraField) {
          vars.extra = parseExtraField(extraField, vars);
          return records.pull(vars.fileCommentLength);
        })
        .then(function(comment) {
          vars.comment = comment;
          vars.type = (vars.uncompressedSize === 0 && /[\/\\]$/.test(vars.path)) ? 'Directory' : 'File';
          vars.stream = function(_password) {
            return unzip(source, vars.offsetToLocalFileHeader,_password, vars);
          };
          vars.buffer = function(_password) {
            return BufferStream(vars.stream(_password));
          };
          return vars;
        });
      });
    });

    return Promise.props(vars);
  });
};