# all files / lib/spdy-transport/protocol/http2/ framer.js

96.15% Statements 225/234
86.73% Branches 98/113
100% Functions 51/51
96.46% Lines 218/226

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     'use strict'

    var transport = require('../../../spdy-transport')
    var base = transport.protocol.base
    var constants = require('./').constants

    var assert = require('assert')
    var util = require('util')
    var WriteBuffer = require('wbuf')
    var OffsetBuffer = require('obuf')
    var debug = require('debug')('spdy:framer')
    var debugExtra = require('debug')('spdy:framer:extra')

    function Framer (options) {
      base.Framer.call(this, options)

      this.maxFrameSize = constants.INITIAL_MAX_FRAME_SIZE
    }
    util.inherits(Framer, base.Framer)
    module.exports = Framer

    Framer.create = function create (options) {
      return new Framer(options)
    }

    Framer.prototype.setMaxFrameSize = function setMaxFrameSize (size) {
      this.maxFrameSize = size
    }

    Framer.prototype._frame = function _frame (frame, body, callback) {
      debug('id=%d type=%s', frame.id, frame.type)

      var buffer = new WriteBuffer()

      buffer.reserve(constants.FRAME_HEADER_SIZE)
      var len = buffer.skip(3)
      buffer.writeUInt8(constants.frameType[frame.type])
      buffer.writeUInt8(frame.flags)
      buffer.writeUInt32BE(frame.id & 0x7fffffff)

      body(buffer)

      var frameSize = buffer.size - constants.FRAME_HEADER_SIZE
      len.writeUInt24BE(frameSize)

      var chunks = buffer.render()
      var toWrite = {
        stream: frame.id,
        priority: frame.priority === undefined ? false : frame.priority,
        chunks: chunks,
        callback: callback
      }

      if (this.window && frame.type === 'DATA') {
        var self = this
        this._resetTimeout()
        this.window.send.update(-frameSize, function () {
          self._resetTimeout()
          self.schedule(toWrite)
        })
      } else {
        this._resetTimeout()
        this.schedule(toWrite)
      }

      return chunks
    }

    Framer.prototype._split = function _split (frame) {
      var buf = new OffsetBuffer()
      for (var i = 0; i < frame.chunks.length; i++) { buf.push(frame.chunks[i]) }

      var frames = []
      while (!buf.isEmpty()) {
        // First frame may have reserved bytes in it
        var size = this.maxFrameSize
        if (frames.length === 0) {
          size -= frame.reserve
        }
        size = Math.min(size, buf.size)

        var frameBuf = buf.clone(size)
        buf.skip(size)

        frames.push({
          size: frameBuf.size,
          chunks: frameBuf.toChunks()
        })
      }

      return frames
    }

    Framer.prototype._continuationFrame = function _continuationFrame (frame,
                                                                      body,
                                                                      callback) {
      var frames = this._split(frame)

      frames.forEach(function (subFrame, i) {
        var isFirst = i === 0
        var isLast = i === frames.length - 1

        var flags = isLast ? constants.flags.END_HEADERS : 0

        // PRIORITY and friends
        if (isFirst) {
          flags |= frame.flags
        }

        this._frame({
          id: frame.id,
          priority: false,
          type: isFirst ? frame.type : 'CONTINUATION',
          flags: flags
        }, function (buf) {
          // Fill those reserved bytes
          if (isFirst && body) { body(buf) }

          buf.reserve(subFrame.size)
          for (var i = 0; i < subFrame.chunks.length; i++) { buf.copyFrom(subFrame.chunks[i]) }
        }, isLast ? callback : null)
      }, this)

      if (frames.length === 0) {
        this._frame({
          id: frame.id,
          priority: false,
          type: frame.type,
          flags: frame.flags | constants.flags.END_HEADERS
        }, function (buf) {
          Eif (body) { body(buf) }
        }, callback)
      }
    }

    Framer.prototype._compressHeaders = function _compressHeaders (headers,
                                                                  pairs,
                                                                  callback) {
      Object.keys(headers || {}).forEach(function (name) {
        var lowName = name.toLowerCase()

        // Not allowed in HTTP2
        switch (lowName) {
          case 'host':
          case 'connection':
          case 'keep-alive':
          case 'proxy-connection':
          case 'transfer-encoding':
          case 'upgrade':
            return
        }

        // Should be in `pairs`
        if (/^:/.test(lowName)) {
          return
        }

        // Do not compress, or index Cookie field (for security reasons)
        var neverIndex = lowName === 'cookie' || lowName === 'set-cookie'

        var value = headers[name]
        if (Array.isArray(value)) {
          for (var i = 0; i < value.length; i++) {
            pairs.push({
              name: lowName,
              value: value[i] + '',
              neverIndex: neverIndex,
              huffman: !neverIndex
            })
          }
        } else {
          pairs.push({
            name: lowName,
            value: value + '',
            neverIndex: neverIndex,
            huffman: !neverIndex
          })
        }
      })

      assert(this.compress !== null, 'Framer version not initialized')
      debugExtra('compressing headers=%j', pairs)
      this.compress.write([ pairs ], callback)
    }

    Framer.prototype._isDefaultPriority = function _isDefaultPriority (priority) {
      if (!priority) { return true }

      return !priority.parent &&
             priority.weight === constants.DEFAULT &&
             !priority.exclusive
    }

    Framer.prototype._defaultHeaders = function _defaultHeaders (frame, pairs) {
      Iif (!frame.path) {
        throw new Error('`path` is required frame argument')
      }

      pairs.push({
        name: ':method',
        value: frame.method || base.constants.DEFAULT_METHOD
      })
      pairs.push({ name: ':path', value: frame.path })
      pairs.push({ name: ':scheme', value: frame.scheme || 'https' })
      pairs.push({
        name: ':authority',
        value: frame.host ||
               frame.headers && frame.headers.host ||
               base.constants.DEFAULT_HOST
      })
    }

    Framer.prototype._headersFrame = function _headersFrame (kind, frame, callback) {
      var pairs = []

      if (kind === 'request') {
        this._defaultHeaders(frame, pairs)
      } else if (kind === 'response') {
        pairs.push({ name: ':status', value: (frame.status || 200) + '' })
      }

      var self = this
      this._compressHeaders(frame.headers, pairs, function (err, chunks) {
        Iif (err) {
          if (callback) {
            return callback(err)
          } else {
            return self.emit('error', err)
          }
        }

        var reserve = 0

        // If priority info is present, and the values are not default ones
        // reserve space for the priority info and add PRIORITY flag
        var priority = frame.priority
        if (!self._isDefaultPriority(priority)) { reserve = 5 }

        var flags = reserve === 0 ? 0 : constants.flags.PRIORITY

        // Mostly for testing
        if (frame.fin) {
          flags |= constants.flags.END_STREAM
        }

        self._continuationFrame({
          id: frame.id,
          type: 'HEADERS',
          flags: flags,
          reserve: reserve,
          chunks: chunks
        }, function (buf) {
          if (reserve === 0) {
            return
          }

          buf.writeUInt32BE((priority.exclusive ? 0x80000000 : 0) |
                            priority.parent)
          buf.writeUInt8((priority.weight | 0) - 1)
        }, callback)
      })
    }

    Framer.prototype.requestFrame = function requestFrame (frame, callback) {
      return this._headersFrame('request', frame, callback)
    }

    Framer.prototype.responseFrame = function responseFrame (frame, callback) {
      return this._headersFrame('response', frame, callback)
    }

    Framer.prototype.headersFrame = function headersFrame (frame, callback) {
      return this._headersFrame('headers', frame, callback)
    }

    Framer.prototype.pushFrame = function pushFrame (frame, callback) {
      var self = this

      function compress (headers, pairs, callback) {
        self._compressHeaders(headers, pairs, function (err, chunks) {
          Iif (err) {
            if (callback) {
              return callback(err)
            } else {
              return self.emit('error', err)
            }
          }

          callback(chunks)
        })
      }

      function sendPromise (chunks) {
        self._continuationFrame({
          id: frame.id,
          type: 'PUSH_PROMISE',
          reserve: 4,
          chunks: chunks
        }, function (buf) {
          buf.writeUInt32BE(frame.promisedId)
        })
      }

      function sendResponse (chunks, callback) {
        var priority = frame.priority
        var isDefaultPriority = self._isDefaultPriority(priority)
        var flags = isDefaultPriority ? 0 : constants.flags.PRIORITY

        // Mostly for testing
        Iif (frame.fin) {
          flags |= constants.flags.END_STREAM
        }

        self._continuationFrame({
          id: frame.promisedId,
          type: 'HEADERS',
          flags: flags,
          reserve: isDefaultPriority ? 0 : 5,
          chunks: chunks
        }, function (buf) {
          if (isDefaultPriority) {
            return
          }

          buf.writeUInt32BE((priority.exclusive ? 0x80000000 : 0) |
                            priority.parent)
          buf.writeUInt8((priority.weight | 0) - 1)
        }, callback)
      }

      this._checkPush(function (err) {
        if (err) {
          return callback(err)
        }

        var pairs = {
          promise: [],
          response: []
        }

        self._defaultHeaders(frame, pairs.promise)
        pairs.response.push({ name: ':status', value: (frame.status || 200) + '' })

        compress(frame.headers, pairs.promise, function (promiseChunks) {
          sendPromise(promiseChunks)
          compress(frame.response, pairs.response, function (responseChunks) {
            sendResponse(responseChunks, callback)
          })
        })
      })
    }

    Framer.prototype.priorityFrame = function priorityFrame (frame, callback) {
      this._frame({
        id: frame.id,
        priority: false,
        type: 'PRIORITY',
        flags: 0
      }, function (buf) {
        var priority = frame.priority
        buf.writeUInt32BE((priority.exclusive ? 0x80000000 : 0) |
                          priority.parent)
        buf.writeUInt8((priority.weight | 0) - 1)
      }, callback)
    }

    Framer.prototype.dataFrame = function dataFrame (frame, callback) {
      var frames = this._split({
        reserve: 0,
        chunks: [ frame.data ]
      })

      var fin = frame.fin ? constants.flags.END_STREAM : 0

      var self = this
      frames.forEach(function (subFrame, i) {
        var isLast = i === frames.length - 1
        var flags = 0
        if (isLast) {
          flags |= fin
        }

        self._frame({
          id: frame.id,
          priority: frame.priority,
          type: 'DATA',
          flags: flags
        }, function (buf) {
          buf.reserve(subFrame.size)
          for (var i = 0; i < subFrame.chunks.length; i++) { buf.copyFrom(subFrame.chunks[i]) }
        }, isLast ? callback : null)
      })

      // Empty DATA
      if (frames.length === 0) {
        this._frame({
          id: frame.id,
          priority: frame.priority,
          type: 'DATA',
          flags: fin
        }, function (buf) {
          // No-op
        }, callback)
      }
    }

    Framer.prototype.pingFrame = function pingFrame (frame, callback) {
      this._frame({
        id: 0,
        type: 'PING',
        flags: frame.ack ? constants.flags.ACK : 0
      }, function (buf) {
        buf.copyFrom(frame.opaque)
      }, callback)
    }

    Framer.prototype.rstFrame = function rstFrame (frame, callback) {
      this._frame({
        id: frame.id,
        type: 'RST_STREAM',
        flags: 0
      }, function (buf) {
        buf.writeUInt32BE(constants.error[frame.code])
      }, callback)
    }

    Framer.prototype.prefaceFrame = function prefaceFrame (callback) {
      debug('preface')
      this._resetTimeout()
      this.schedule({
        stream: 0,
        priority: false,
        chunks: [ constants.PREFACE_BUFFER ],
        callback: callback
      })
    }

    Framer.prototype.settingsFrame = function settingsFrame (options, callback) {
      var key = JSON.stringify(options)

      var settings = Framer.settingsCache[key]
      if (settings) {
        debug('cached settings')
        this._resetTimeout()
        this.schedule({
          id: 0,
          priority: false,
          chunks: settings,
          callback: callback
        })
        return
      }

      var params = []
      for (var i = 0; i < constants.settingsIndex.length; i++) {
        var name = constants.settingsIndex[i]
        if (!name) {
          continue
        }

        // value: Infinity
        if (!isFinite(options[name])) {
          continue
        }

        Eif (options[name] !== undefined) {
          params.push({ key: i, value: options[name] })
        }
      }

      var bodySize = params.length * 6

      var chunks = this._frame({
        id: 0,
        type: 'SETTINGS',
        flags: 0
      }, function (buffer) {
        buffer.reserve(bodySize)
        for (var i = 0; i < params.length; i++) {
          var param = params[i]

          buffer.writeUInt16BE(param.key)
          buffer.writeUInt32BE(param.value)
        }
      }, callback)

      Framer.settingsCache[key] = chunks
    }
    Framer.settingsCache = {}

    Framer.prototype.ackSettingsFrame = function ackSettingsFrame (callback) {
      /* var chunks = */ this._frame({
        id: 0,
        type: 'SETTINGS',
        flags: constants.flags.ACK
      }, function (buffer) {
        // No-op
      }, callback)
    }

    Framer.prototype.windowUpdateFrame = function windowUpdateFrame (frame,
                                                                    callback) {
      this._frame({
        id: frame.id,
        type: 'WINDOW_UPDATE',
        flags: 0
      }, function (buffer) {
        buffer.reserve(4)
        buffer.writeInt32BE(frame.delta)
      }, callback)
    }

    Framer.prototype.goawayFrame = function goawayFrame (frame, callback) {
      this._frame({
        type: 'GOAWAY',
        id: 0,
        flags: 0
      }, function (buf) {
        buf.reserve(8)

        // Last-good-stream-ID
        buf.writeUInt32BE(frame.lastId & 0x7fffffff)
        // Code
        buf.writeUInt32BE(constants.goaway[frame.code])

        // Extra debugging information
        Iif (frame.extra) { buf.write(frame.extra) }
      }, callback)
    }

    Framer.prototype.xForwardedFor = function xForwardedFor (frame, callback) {
      this._frame({
        type: 'X_FORWARDED_FOR',
        id: 0,
        flags: 0
      }, function (buf) {
        buf.write(frame.host)
      }, callback)
    }