Fields.js

// Copyright 2013 SAP AG.
//
// 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.
'use strict';

var util = require('../../util');

exports.read = read;
exports.write = write;
exports.getByteLength = getByteLength;
exports.getArgumentCount = getArgumentCount;

function read(part) {
  var offset = 0;
  var buffer = part.buffer;
  var fields = [];

  var numberOfFields = buffer.readUInt16LE(offset);
  offset += 2;
  var fieldLength;
  for (var i = 0; i < numberOfFields; i++) {
    fieldLength = buffer[offset];
    offset += 1;
    if (fieldLength > 245) {
      fieldLength = buffer.readUInt16LE(offset);
      offset += 2;
    }
    fields.push(buffer.slice(offset, offset + fieldLength));
    offset += fieldLength;
  }
  return fields;
}

function write(part, fields) {
  /* jshint validthis:true */

  var offset = 0;
  part = part || {};
  fields = fields || this;

  var byteLength = getByteLength(fields);
  var buffer = Buffer.allocUnsafe(byteLength);

  buffer.writeUInt16LE(fields.length, 0);
  offset += 2;

  var field, fieldLength, data;
  for (var i = 0; i < fields.length; i++) {
    field = fields[i];
    if (Buffer.isBuffer(field)) {
      data = field;
    } else if (util.isArray(field)) {
      data = write({}, field).buffer;
    } else {
      data = Buffer.from(field, 'ascii');
    }
    fieldLength = data.length;
    if (fieldLength <= 245) {
      buffer[offset] = fieldLength;
      offset += 1;
    } else {
      buffer[offset] = 0xf6;
      offset += 1;
      buffer.writeUInt16LE(fieldLength, offset);
      offset += 2;
    }
    data.copy(buffer, offset);
    offset += fieldLength;
  }
  part.argumentCount = getArgumentCount(fields);
  part.buffer = buffer;
  return part;
}

function getByteLength(fields) {
  var byteLength = 2;
  var fieldLength;
  for (var i = 0; i < fields.length; i++) {
    fieldLength = getByteLengthOfField(fields[i]);
    if (fieldLength <= 245) {
      byteLength += fieldLength + 1;
    } else {
      byteLength += fieldLength + 3;
    }
  }
  return byteLength;
}

function getArgumentCount(fields) {
  /* jshint unused:false */
  return 1;
}

function getByteLengthOfField(field) {
  if (Buffer.isBuffer(field)) {
    return field.length;
  } else if (util.isArray(field)) {
    return getByteLength(field);
  }
  return Buffer.byteLength(field, 'ascii');
}