git ssb

1
/**
2
 * This is the Ethereum interface that is exposed to the WASM instance which
3
 * enables to interact with the Ethereum Environment
4
 */
5
const constants = require('./constants.js')
6
7
// The interface exposed to the WebAessembly Core
8
module.exports = class Interface {
9
  constructor (environment) {
10
    this.environment = environment
11
  }
12
13
  get exportTable () {
14
    let exportMethods = [
15
      // include all the public methods according to the Ethereum Environment Interface (EEI)
16
      // FIXME: this currently doesn't match EEI r0
17
      'useGas',
18
      'gas',
19
      'address',
20
      'balance',
21
      'origin',
22
      'caller',
23
      'callValue',
24
      'callDataSize',
25
      'callDataCopy',
26
      'codeSize',
27
      'codeCopy',
28
      'extCodeSize',
29
      'extCodeCopy',
30
      'gasPrice',
31
      'blockHash',
32
      'coinbase',
33
      'timestamp',
34
      'number',
35
      'difficulty',
36
      'gasLimit',
37
      'log',
38
      'create',
39
      'call',
40
      'callDelegate',
41
      'sstore',
42
      'sload',
43
      'return',
44
      'suicide'
45
    ]
46
    let ret = {}
47
    exportMethods.forEach((method) => {
48
      ret[method] = this[method].bind(this)
49
    })
50
    return ret
51
  }
52
53
  setModule (mod) {
54
    this.module = mod
55
  }
56
57
  /**
58
   * Subtracts an amount to the gas counter
59
   * @param {integer} amount the amount to subtract to the gas counter
60
   */
61
  useGas (amount) {
62
    if (amount > 0) {
63
      if (this.environment.gasLimit < amount) {
64
        throw new Error('Ran out of gas')
65
      }
66
      this.environment.gasLimit -= amount
67
    }
68
  }
69
70
  /**
71
   * Returns the current amount of gas
72
   * @return {integer}
73
   */
74
  gas () {
75
    return this.environment.gasLimit
76
  }
77
78
  /**
79
   * Gets address of currently executing account and loads it into memory at
80
   * the given offset.
81
   * @param {integer} offset
82
   */
83
  address (offset) {
84
    this.setMemory(offset, constants.ADDRESS_SIZE_BYTES, this.environment.address)
85
  }
86
87
  /**
88
   * Gets balance of the given account and loads it into memory at the given
89
   * offset.
90
   * @param {integer} addressOffset the memory offset to laod the address
91
   * @param {integer} resultOffset
92
   */
93
  balance (addressOffset, offset) {
94
    const address = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
95
    // call the parent contract and ask for the balance of one of its child contracts
96
    const balance = this.environment.parent.environment.getBalance(address)
97
    this.setMemory(offset, constants.BALANCE_SIZE_BYTES, balance)
98
  }
99
100
  /**
101
   * Gets the execution's origination address and loads it into memory at the
102
   * given offset. This is the sender of original transaction; it is never an
103
   * account with non-empty associated code.
104
   * @param {integer} offset
105
   */
106
  origin (offset) {
107
    this.setMemory(offset, constants.ADDRESS_SIZE_BYTES, this.environment.origin)
108
  }
109
110
  /**
111
   * Gets caller address and loads it into memory at the given offset. This is
112
   * the address of the account that is directly responsible for this execution.
113
   * @param {integer} offset
114
   */
115
  caller (offset) {
116
    this.setMemory(offset, constants.ADDRESS_SIZE_BYTES, this.environment.caller)
117
  }
118
119
  /**
120
   * Gets the deposited value by the instruction/transaction responsible for
121
   * this execution and loads it into memory at the given location.
122
   * @param {integer} offset
123
   */
124
  callValue (offset) {
125
    this.setMemory(offset, constants.BALANCE_SIZE_BYTES, this.environment.callValue.toBuffer())
126
  }
127
128
  /**
129
   * Get size of input data in current environment. This pertains to the input
130
   * data passed with the message call instruction or transaction.
131
   * @return {integer}
132
   */
133
  callDataSize () {
134
    return this.environment.callData.length
135
  }
136
137
  /**
138
   * Copys the input data in current environment to memory. This pertains to
139
   * the input data passed with the message call instruction or transaction.
140
   * @param {integer} offset the offset in memory to load into
141
   * @param {integer} dataOffset the offset in the input data
142
   * @param {integer} length the length of data to copy
143
   */
144
  callDataCopy (offset, dataOffset, length) {
145
    const callData = Buffer.from(this.environment.callData.slice(dataOffset, dataOffset + length)).reverse()
146
    this.setMemory(offset, length, callData)
147
  }
148
149
  /**
150
   * Gets the size of code running in current environment.
151
   * @return {interger}
152
   */
153
  codeSize () {
154
    return this.environment.code.length
155
  }
156
157
  /**
158
   * Copys the code running in current environment to memory.
159
   * @param {integer} offset the memory offset
160
   * @param {integer} codeOffset the code offset
161
   * @param {integer} length the length of code to copy
162
   */
163
  codeCopy (offset, codeOffset, length) {
164
    const code = new Uint8Array(this.environment.code, codeOffset, length)
165
    this.setMemory(offset, length, code)
166
  }
167
168
  /**
169
   * Get size of an account’s code.
170
   * @param {integer} addressOffset the offset in memory to load the address from
171
   * @return {integer}
172
   */
173
  extCodeSize (addressOffset) {
174
    const address = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
175
    const code = this.environment.getCode(address)
176
    return code.length
177
  }
178
179
  /**
180
   * Copys the code of an account to memory.
181
   * @param {integer} addressOffset the memory offset of the address
182
   * @param {integer} offset the memory offset
183
   * @param {integer} codeOffset the code offset
184
   * @param {integer} length the length of code to copy
185
   */
186
  extCodeCopy (addressOffset, offset, codeOffset, length) {
187
    const address = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
188
    let code = this.environment.getCode(address)
189
   code = new Uint8Array(code, codeOffset, length)
190
    this.setMemory(offset, length, code)
191
  }
192
193
  /**
194
   * Gets price of gas in current environment.
195
   * @return {integer}
196
   */
197
  gasPrice () {
198
    return this.environment.gasPrice
199
  }
200
201
  /**
202
   * Gets the hash of one of the 256 most recent complete blocks.
203
   * @param {integer} number which block to load
204
   * @param {integer} offset the offset to load the hash into
205
   */
206
  blockHash (number, offset) {
207
    const hash = this.environment.getBlockHash(number)
208
    this.setMemory(offset, 32, hash)
209
  }
210
211
  /**
212
   * Gets the block’s beneficiary address and loads into memory.
213
   * @param offset
214
   */
215
  coinbase (offset) {
216
    this.setMemory(offset, constants.ADDRESS_SIZE_BYTES, this.environment.coinbase)
217
  }
218
219
  /**
220
   * Get the block’s timestamp.
221
   * @return {integer}
222
   */
223
  timestamp () {
224
    return this.environment.timestamp
225
  }
226
227
  /**
228
   * Get the block’s number.
229
   * @return {integer}
230
   */
231
  number () {
232
    return this.environment.number
233
  }
234
235
  /**
236
   * Get the block’s difficulty.
237
   * @return {integer}
238
   */
239
  difficulty () {
240
    return this.environment.difficulty
241
  }
242
243
  /**
244
   * Get the block’s gas limit.
245
   * @return {integer}
246
   */
247
  gasLimit () {
248
    return this.environment.gasLimit
249
  }
250
251
  /**
252
   * Creates a new log in the current environment
253
   * @param {integer} dataOffset the offset in memory to load the memory
254
   * @param {integer} length the data length
255
   * TODO: replace with variadic
256
   */
257
  log (dataOffset, length, topic1, topic2, topic3, topic4, topic5) {
258
    const data = this.getMemory(dataOffset, length)
259
    this.environment.logs.push({
260
      data: data,
261
      topics: [topic1, topic2, topic3, topic4, topic5]
262
    })
263
  }
264
265
  /**
266
   * Creates a new contract with a given value.
267
   * @param {integer} valueOffset the offset in memory to the value from
268
   * @param {integer} dataOffset the offset to load the code for the new contract from
269
   * @param {integer} length the data length
270
   */
271
  create (valueOffset, dataOffset, length) {
272
    const value = this.getMemory(valueOffset, constants.BALANCE_SIZE_BYTES)
273
    const data = this.getMemory(dataOffset, length)
274
    const result = this.environment.create(value, data)
275
    return result
276
  }
277
278
  /**
279
   * Sends a message with arbiatary data to a given address path
280
   * @param {integer} addressOffset the offset to load the address path from
281
   * @param {integer} valueOffset the offset to load the value from
282
   * @param {integer} dataOffset the offset to load data from
283
   * @param {integer} dataLength the length of data
284
   * @param {integer} resultOffset the offset to store the result data at
285
   * @param {integer} resultLength
286
   * @param {integer} gas
287
   * @return {integer} Returns 1 or 0 depending on if the VM trapped on the message or not
288
   * TODO: add proper gas counting
289
   */
290
  call (addressOffset, valueOffset, dataOffset, dataLength, resultOffset, resultLength, gas) {
291
    if (gas === undefined) {
292
      gas = this.gasLeft()
293
    }
294
    // Load the params from mem
295
    const address = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
296
    const value = this.getMemory(valueOffset, constants.BALANCE_SIZE_BYTES)
297
    const data = this.getMemory(dataOffset, dataLength)
298
    // Run the call
299
    const [result, errorCode] = this.environment.call(gas, address, value, data)
300
    this.setMemory(resultOffset, resultLength, result)
301
    return errorCode
302
  }
303
304
  /**
305
   * Message-call into this account with an alternative account’s code, but
306
   * persisting the current values for sender and value.
307
   * @param {integer} gas
308
   * @param {integer} addressOffset the offset to load the address path from
309
   * @param {integer} valueOffset the offset to load the value from
310
   * @param {integer} dataOffset the offset to load data from
311
   * @param {integer} dataLength the length of data
312
   * @param {integer} resultOffset the offset to store the result data at
313
   * @param {integer} resultLength
314
   * @return {integer} Returns 1 or 0 depending on if the VM trapped on the message or not
315
   */
316
  callDelegate (gas, addressOffset, dataOffset, dataLength, resultOffset, resultLength) {
317
    const data = this.getMemory(dataOffset, dataLength)
318
    const address = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
319
    const [result, errorCode] = this.environment.callDelegate(gas, address, data)
320
    this.setMemory(resultOffset, resultLength, result)
321
    return errorCode
322
  }
323
324
  /**
325
   * store a value at a given path in long term storage which are both loaded
326
   * from Memory
327
   * @param {interger} pathOffest the memory offset to load the the path from
328
   * @param {interger} valueOffset the memory offset to load the value from
329
   */
330
  sstore (pathOffset, valueOffset) {
331
    const path = new Buffer(this.getMemory(pathOffset, 32)).toString('hex')
332
    // copy the value
333
    const value = this.getMemory(valueOffset, 32).slice(0)
334
    const oldValue = this.environment.state.get(path)
335
    const valIsZero = value.every((i) => i === 0)
336
337
    // write
338
    if (!valIsZero && !oldValue) {
339
      this.environment.gasLimit -= 15000
340
    }
341
342
    // delete
343
    if (valIsZero && oldValue) {
344
      this.environment.gasRefund += 15000
345
      this.environment.state.delete(path)
346
    } else {
347
      this.environment.state.set(path, value)
348
    }
349
  }
350
351
  /**
352
   * reterives a value at a given path in long term storage
353
   * @param {interger} pathOffest the memory offset to load the the path from
354
   * @param {interger} resultOffset the memory offset to load the value from
355
   */
356
  sload (pathOffset, resultOffset) {
357
    const path = new Buffer(this.getMemory(pathOffset, 32)).toString('hex')
358
    const result = this.environment.state.get(path)
359
    this.setMemory(resultOffset, 32, result)
360
  }
361
362
  /**
363
   * Halt execution returning output data.
364
   * @param {integer} offset the offset of the output data.
365
   * @param {integer} length the length of the output data.
366
   */
367
  return (offset, length) {
368
    this.environment.returnValue = this.getMemory(offset, length)
369
  }
370
371
  /**
372
   * Halt execution and register account for later deletion giving the remaining
373
   * balance to an address path
374
   * @param {integer} offset the offset to load the address from
375
   */
376
  suicide (addressOffset) {
377
    this.environment.suicideAddress = this.getMemory(addressOffset, constants.ADDRESS_SIZE_BYTES)
378
  }
379
380
  getMemory (offset, length) {
381
    return new Uint8Array(this.module.exports.memory, offset, length)
382
  }
383
384
  setMemory (offset, length, value) {
385
    const memory = new Uint8Array(this.module.exports.memory, offset, length)
386
    memory.set(value)
387
  }
388
}
389
390
//
391
// Polyfill required unless this is sorted: https://bugs.chromium.org/p/chromium/issues/detail?id=633895
392
//
393
// Polyfill from: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_objects/Function/bind
394
//
395
Function.prototype.bind = function (oThis) { // eslint-disable-line
396
  if (typeof this !== 'function') {
397
    // closest thing possible to the ECMAScript 5
398
    // internal IsCallable function
399
    throw new TypeError('Function.prototype.bind - what is trying to be bound is not callable')
400
  }
401
402
  var aArgs = Array.prototype.slice.call(arguments, 1)
403
  var fToBind = this
404
  var fNOP = function () {}
405
  var fBound = function () {
406
    return fToBind.apply(this instanceof fNOP ? this : oThis,
407
     aArgs.concat(Array.prototype.slice.call(arguments)))
408
  }
409
410
  if (this.prototype) {
411
    // Function.prototype doesn't have a prototype property
412
    fNOP.prototype = this.prototype
413
  }
414
415
  fBound.prototype = new fNOP() // eslint-disable-line new-cap
416
417
  return fBound
418
}
419