git ssb

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var ssbKeys = require('ssb-keys')
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var timestamp = require('monotonic-timestamp')
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var isRef = require('ssb-ref')
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var isHash = isRef.isHash
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var isFeedId = isRef.isFeedId
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var encode = exports.encode = function (obj) {
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  return JSON.stringify(obj, null, 2)
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}
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function isString (s) {
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  return 'string' === typeof s
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}
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function isInteger (n) {
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  return ~~n === n
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}
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function isObject (o) {
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  return o && 'object' === typeof o
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}
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function clone (obj) {
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  var o = {}
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  for(var k in obj) o[k] = obj[k];
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  return o
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}
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function isEncrypted (str) {
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  return isString(str) && /^[0-9A-Za-z\/+]+={0,2}\.box/.test(str)
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}
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exports.toBuffer = function (b) {
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  if('string' == typeof b) return new Buffer(b, 'base64')
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  return b
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}
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exports.BatchQueue = function BatchQueue (db) {
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  var batch = [], writing = false
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  function drain () {
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    writing = true
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    var _batch = batch
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    batch = []
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    db.batch(_batch, function () {
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      writing = false
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      write.size = batch.length
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      if(batch.length) drain()
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      _batch.forEach(function (op) {
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        op.cb(null, {key:op.key, value: op.value})
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      })
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    })
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  }
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  function write (op) {
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    batch.push(op)
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    write.size = batch.length
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    if(!writing) drain()
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  }
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  write.size = 0
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  return write
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}
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exports.create = function (keys, type, content, prev, prev_key, sign_cap) {
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  //this noise is to handle things calling this with legacy api.
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  if(isString(type) && (Buffer.isBuffer(content) || isString(content)))
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    content = {type: type, value: content}
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  if(isObject(content))
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    content.type = content.type || type
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  //noise end
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  prev_key = !prev_key && prev ? ('%'+ssbKeys.hash(encode(prev))) : prev_key || null
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  return ssbKeys.signObj(keys, sign_cap, {
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    previous: prev_key,
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    author: keys.id,
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    sequence: prev ? prev.sequence + 1 : 1,
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    timestamp: timestamp(),
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    hash: 'sha256',
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    content: content,
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  })
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}
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var isInvalidContent = exports.isInvalidContent = function (content) {
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  if(!isEncrypted(content)) {
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    type = content.type
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    if (!(isString(type) && type.length <= 52 && type.length >= 3)) {
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      return new Error('type must be a string' +
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        '3 <= type.length < 52, was:' + type
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      )
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    }
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  }
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  return false
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}
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exports.isInvalidShape = function (msg) {
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  if(
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    !isObject(msg) ||
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    !isInteger(msg.sequence) ||
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    !isFeedId(msg.author) ||
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    !(isObject(msg.content) || isEncrypted(msg.content))
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  )
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    return new Error('message has invalid properties')
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  //allow encrypted messages, where content is a base64 string.
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  var asJson = encode(msg)
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  if (asJson.length > 8192) // 8kb
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    return new Error( 'encoded message must not be larger than 8192 bytes')
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  return isInvalidContent(msg.content)
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}
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exports.isInvalid = function (pub, msg, previous, sign_cap) {
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  // :TODO: is there a faster way to measure the size of this message?
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  var key = previous.key
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  var prev = previous.value
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  if(prev) {
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    if(msg.previous !== key)
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      return new Error(
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          'expected previous: '
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        + key
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        + 'but found:' + msg.previous
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      )
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    if(msg.sequence !== prev.sequence + 1
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     || msg.timestamp <= prev.timestamp)
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        return new Error('out of order')
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  }
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  else {
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    if(!(msg.previous == null
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      && msg.sequence === 1 && msg.timestamp > 0))
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        return new Error('expected initial message')
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  }
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  if(msg.author !== pub) {
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    return new Error(
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        'expected different author:'
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      + hash(pub.public || pub).toString('base64')
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      + 'but found:' + msg.author.toString('base64')
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    )
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  }
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  if(!ssbKeys.verifyObj(pub, sign_cap, msg))
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    return new Error('signature was invalid')
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  return false
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}
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