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stream.js
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stream.js
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// FCGI stream
//
// Copyright 2012 Iris Couch
//
// 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.
// Chop a data stream (of buffers) on FastCGI record boundaries.
var util = require('util')
var stream = require('stream')
module.exports = FastCGIStream
util.inherits(FastCGIStream, stream)
function FastCGIStream (opts) {
var self = this
stream.call(self)
opts = opts || {}
self.log = opts.log || console
self.readable = true
self.writable = true
self.is_ending = false
self.is_sending = true
self.pending_data = []
self.records = []
self.source = null
self.once('pipe', function(src) {
self.source = src
self.on('pipe', function(src) {
var er = new Error('Already have a pipe source')
er.source = self.source
self.error(er)
})
})
}
//
// Readable stream API
//
FastCGIStream.prototype.setEncoding = function(encoding) {
var self = this
throw new Error('setEncoding not allowed, only Buffer is supported') // TODO: Maybe "hex" encoding?
}
FastCGIStream.prototype.pause = function() {
var self = this
self.is_sending = false
if(self.source && self.source.pause)
self.source.pause()
}
FastCGIStream.prototype.resume = function() {
var self = this
self.is_sending = true
if(self.source && self.source.resume)
self.source.resume()
self.emit_records()
}
//
// Writable stream API
//
FastCGIStream.prototype.write = function(data, encoding) {
var self = this
//self.log.log('write: %s', data ? data.length : 'null')
if(data)
self.pending_data.push(data)
self.build_record()
return !self.is_ending
}
FastCGIStream.prototype.build_record = function() {
var self = this
//self.log.log('== Build record')
// The first buffer must at least be a complete header, or nothing can be done.
while(self.pending_data.length > 1 && self.pending_data[0].length < 8) {
//self.log.log('Joining next two chunks to find a header')
var first_chunk = self.pending_data.shift()
, second_chunk = self.pending_data.shift()
self.pending_data.unshift(Buffer.concat([first_chunk, second_chunk]))
}
var pending_bytes = self.pending_data.reduce(function(len, buf) { return len + buf.length }, 0)
//self.log.log('Unprocessed bytes in %d buffers: %d', self.pending_data.length, pending_bytes)
if(pending_bytes < 8)
return self.emit_records() // No more data to process; emit any completed records.
var header = get_header(self.pending_data[0])
//self.log.log('Next header: %j', header)
var record_bytes = 8 + header.body_len + header.pad_len // The header itself + content + padding
if(pending_bytes < record_bytes) {
//self.log.log('Received %d/%d bytes for the record; need %d', pending_bytes, record_bytes, record_bytes - pending_bytes)
return self.emit_records()
}
// At this point, an entire record's worth of data is in the pending queue.
var record = new Buffer(record_bytes)
, offset = 0
//self.log.log('Building record:')
while(offset < record_bytes) {
var bytes_needed = record_bytes - offset
var next_chunk = self.pending_data.shift()
//self.log.log(' At %d/%d, need %d, chunk is %d', offset, record_bytes, bytes_needed, next_chunk.length)
if(next_chunk.length <= bytes_needed) {
// This chunk entirely belongs in the record.
next_chunk.copy(record, offset, 0, next_chunk.length)
offset += next_chunk.length
} else {
// This chunk completes the record and has data left over.
//self.log.log(' Copy %d-%d from chunk which is %d', offset, bytes_needed, next_chunk.length)
next_chunk.copy(record, offset, 0, bytes_needed)
offset += bytes_needed
var partial_chunk = next_chunk.slice(bytes_needed)
//self.log.log(' %d bytes remain after the record, keeping %d', next_chunk.length - bytes_needed, partial_chunk.length)
self.pending_data.unshift(partial_chunk)
}
}
//self.log.log('Built record of size: %d', record.length)
self.records.push(record)
// Run again, to perhaps build up another record (and ultimately emit them).
self.build_record()
}
FastCGIStream.prototype.end = function(data, encoding) {
var self = this
self.is_ending = true
self.writable = false
// Always call write, even with no data, so it can fire the "end" event.
self.write(data, encoding)
if(self.pending_data.length) {
self.log.warn('Unprocessed data after "end" called:')
if(self.pending_data[0].length >= 8)
self.log.warn(' %j', get_header(self.pending_data[0]))
self.pending_data.forEach(function(data) {
self.log.warn(' %s', util.inspect(data))
})
}
}
FastCGIStream.prototype.emit_records = function() {
var self = this
while(self.is_sending && self.records.length > 0) {
var record = self.records.shift()
//self.log.log('emit record: %d bytes', record.length)
self.emit('data', record)
}
// React to possible end-of-data from the source stream.
if(self.is_sending && self.is_ending && self.records.length === 0) {
self.is_ending = false
self.readable = false
//self.log.log('emit: end')
self.emit('end')
}
}
//
// Readable/writable stream API
//
FastCGIStream.prototype.destroy = function() {
var self = this
//self.log.log('destroy')
self.is_dead = true
self.is_ending = false
self.is_sending = false
if(self.source && typeof self.source.destroy === 'function')
self.source.destroy()
}
FastCGIStream.prototype.destroySoon = function() {
var self = this
throw new Error('not implemented')
//return self.request.destroySoon()
}
//
// Internal implementation
//
FastCGIStream.prototype.normalize_data = function(data, encoding) {
var self = this
if(data instanceof Buffer)
data = data.toString(encoding)
else if(typeof data === 'undefined' && typeof encoding === 'undefined')
data = ""
if(typeof data != 'string')
return self.error(new Error('Not a string or Buffer: ' + util.inspect(data)))
if(self.feed !== 'continuous' && self.feed !== 'longpoll')
return self.error(new Error('Must set .feed to "continuous" or "longpoll" before writing data'))
if(self.expect === null)
self.expect = (self.feed == 'longpoll')
? DEFS.longpoll_header
: ""
var prefix = data.substr(0, self.expect.length)
data = data.substr(prefix.length)
var expected_part = self.expect.substr(0, prefix.length)
, expected_remainder = self.expect.substr(expected_part.length)
if(prefix !== expected_part)
return self.error(new Error('Prefix not expected '+util.inspect(expected_part)+': ' + util.inspect(prefix)))
self.expect = expected_remainder
return data
}
FastCGIStream.prototype.error = function(er) {
var self = this
self.readable = false
self.writable = false
self.emit('error', er)
// The write() method sometimes returns this value, so if there was an error, make write() return false.
return false
}
//
// Utilities
//
function get_header(chunk) {
return { 'version' : chunk.readUInt8(0)
, 'type' : chunk.readUInt8(1)
, 'req_id' : chunk.readUInt16BE(2)
, 'body_len': chunk.readUInt16BE(4)
, 'pad_len' : chunk.readUInt8(6)
, 'reserved': chunk.readUInt8(7)
}
}