git ssb

1
/**
2
 * This implements the Ethereum Kernel
3
 * Kernels must implement two methods `codeHandler` and `callHandler` (and `linkHandler` for sharding)
4
 * The Kernel Contract handles the following
5
 * - Interprocess communications
6
 * - Intializing the VM and exposes ROM to it (codeHandler)
7
 * - Expose namespace which VM instance exists and Intializes the Environment (callHandler)
8
 * - Provides some built in contract (runTx, runBlock)
9
 * - Provides resource sharing and limiting via gas
10
 *
11
 *   All State should be stored in the Environment.
12
 *
13
 */
14
15
// The Kernel Exposes this Interface to VM instances it makes
16
const Interface = require('./interface.js')
17
18
// The Kernel Stores all of its state in the Environment. The Interface is used
19
// to by the VM to retrive infromation from the Environment.
20
const Environment = require('./environment.js')
21
const DebugInterface = require('./debugInterface.js')
22
const Address = require('./deps/address.js')
23
const U256 = require('./deps/u256.js')
24
const Utils = require('./deps/utils.js')
25
const Transaction = require('./deps/transaction.js')
26
const Precompile = require('./precompile.js')
27
28
const identityContract = new Address('0x0000000000000000000000000000000000000004')
29
const meteringContract = new Address('0x000000000000000000000000000000000000000A')
30
const transcompilerContract = new Address('0x000000000000000000000000000000000000000B')
31
32
module.exports = class Kernel {
33
  // runs some code in the VM
34
  constructor (environment = new Environment()) {
35
    this.environment = environment
36
    this._runningOps = Promise.resolve()
37
38
    // this.environment.addAccount(identityContract, {})
39
    // this.environment.addAccount(meteringContract, {})
40
    // this.environment.addAccount(transcompilerContract, {})
41
  }
42
43
  // handles running code.
44
  // NOTE: it assumes that wasm will raise an exception if something went wrong,
45
  //       otherwise execution succeeded
46
  codeHandler (code, ethInterface = new Interface(new Environment(), this)) {
47
    // TODO remove
48
    ethInterface.kernel = this
49
    const debugInterface = new DebugInterface(ethInterface.environment)
50
    const module = WebAssembly.Module(code)
51
    const imports = {
52
      'ethereum': ethInterface.exportTable,
53
      'debug': debugInterface.exportTable,
54
55
      // export this for Rust
56
      // FIXME: remove once Rust has proper imports, see https://github.com/ethereum/evm2.0-design/issues/15
57
      'spectest': ethInterface.exportTable,
58
59
      // export this for Binaryen
60
      // FIXME: remove once C has proper imports, see https://github.com/ethereum/evm2.0-design/issues/16
61
      'env': ethInterface.exportTable
62
    }
63
    // add shims
64
    imports.ethereum.useGas = ethInterface.shims.exports.useGas
65
    imports.ethereum.getGasLeft = ethInterface.shims.exports.getGasLeft
66
    imports.ethereum.call = ethInterface.shims.exports.call
67
68
    const instance = this.instance = WebAssembly.Instance(module, imports)
69
70
    ethInterface.setModule(instance)
71
    debugInterface.setModule(instance)
72
73
    if (instance.exports.main) {
74
      instance.exports.main()
75
    }
76
    return this.onDone()
77
  }
78
79
  // returns a promise that resolves when the wasm instance is done running
80
  async onDone () {
81
    let prevOps
82
    while (prevOps !== this._runningOps) {
83
      prevOps = this._runningOps
84
      await this._runningOps
85
    }
86
  }
87
88
  // loads code from the merkle trie and delegates the message
89
  // Detects if code is EVM or WASM
90
  // Detects if the code injection is needed
91
  // Detects if transcompilation is needed
92
  messageHandler (call) {
93
    // FIXME: this is here until these two contracts are compiled to WASM
94
    // The two special contracts (precompiles now, but will be real ones later)
95
    if (call.to.equals(meteringContract)) {
96
      return Precompile.meteringInjector(call)
97
    } else if (call.to.equals(transcompilerContract)) {
98
      return Precompile.transcompiler(call)
99
    } else if (call.to.equals(identityContract)) {
100
      return Precompile.identity(call)
101
    }
102
103
    let account = this.environment.state.get(call.to.toString())
104
    if (!account) {
105
      throw new Error('Account not found: ' + call.to.toString())
106
    }
107
108
    let code = Uint8Array.from(account.get('code'))
109
    if (code.length === 0) {
110
      throw new Error('Contract not found')
111
    }
112
113
    if (!Utils.isWASMCode(code)) {
114
      // throw new Error('Not an eWASM contract')
115
116
      // Transcompile code
117
      // FIXME: decide if these are the right values here: from: 0, gasLimit: 0, value: 0
118
      code = this.callHandler({ from: Address.zero(), to: transcompilerContract, gasLimit: 0, value: new U256(0), data: code }).returnValue
119
120
      if (code[0] === 0) {
121
        code = code.slice(1)
122
      } else {
123
        throw new Error('Transcompilation failed: ' + Buffer.from(code).slice(1).toString())
124
      }
125
    }
126
127
    // creats a new Kernel
128
    const environment = new Environment()
129
    environment.parent = this
130
131
    // copy the transaction details
132
    environment.code = code
133
    environment.address = call.to
134
    // FIXME: make distinction between origin and caller
135
    environment.origin = call.from
136
    environment.caller = call.from
137
    environment.callData = call.data
138
    environment.callValue = call.value
139
    environment.gasLeft = call.gasLimit
140
141
    environment.callHandler = this.callHandler.bind(this)
142
    environment.createHandler = this.createHandler.bind(this)
143
144
    const kernel = new Kernel(environment)
145
    kernel.codeHandler(code, new Interface(environment))
146
147
    // self destructed
148
    if (environment.selfDestruct) {
149
      const balance = this.state.get(call.to.toString()).get('balance')
150
      const beneficiary = this.state.get(environment.selfDestructAddress)
151
      beneficiary.set('balance', beneficiary.get('balance').add(balance))
152
      this.state.delete(call.to.toString())
153
    }
154
155
    // generate new stateroot
156
    // this.environment.state.set(address, { stateRoot: stateRoot })
157
158
    return {
159
      executionOutcome: 1, // success
160
      gasLeft: new U256(environment.gasLeft),
161
      gasRefund: new U256(environment.gasRefund),
162
      returnValue: environment.returnValue,
163
      selfDestruct: environment.selfDestruct,
164
      selfDestructAddress: environment.selfDestructAddress,
165
      logs: environment.logs
166
    }
167
  }
168
169
  createHandler (create) {
170
    let code = create.data
171
172
    // Inject metering
173
    if (Utils.isWASMCode(code)) {
174
      // FIXME: decide if these are the right values here: from: 0, gasLimit: 0, value: 0
175
      code = this.callHandler({ from: Address.zero(), to: meteringContract, gasLimit: 0, value: new U256(0), data: code }).returnValue
176
177
      if (code[0] === 0) {
178
        code = code.slice(1)
179
      } else {
180
        throw new Error('Metering injection failed: ' + Buffer.from(code).slice(1).toString())
181
      }
182
    }
183
184
    let address = Utils.newAccountAddress(create.from, code)
185
186
    this.environment.addAccount(address.toString(), {
187
      balance: create.value,
188
      code: code
189
    })
190
191
    // Run code and take return value as contract code
192
    // FIXME: decide if these are the right values here: value: 0, data: ''
193
    code = this.callHandler({ from: create.from, to: address, gasLimit: create.gasLimit, value: new U256(0), data: new Uint8Array() }).returnValue
194
195
    // FIXME: special handling for selfdestruct
196
197
    this.environment.state.get(address.toString()).set('code', code)
198
199
    return {
200
      executionOutcome: 1, // success
201
      gasLeft: new U256(this.environment.gasLeft),
202
      gasRefund: new U256(this.environment.gasRefund),
203
      accountCreated: address,
204
      logs: this.environment.logs
205
    }
206
  }
207
208
  // run tx; the tx message handler
209
  runTx (tx, environment = new Environment()) {
210
    this.environment = environment
211
212
    if (Buffer.isBuffer(tx) || typeof tx === 'string') {
213
      tx = new Transaction(tx)
214
      if (!tx.valid) {
215
        throw new Error('Invalid transaction signature')
216
      }
217
    }
218
219
    // look up sender
220
    let fromAccount = this.environment.state.get(tx.from.toString())
221
    if (!fromAccount) {
222
      throw new Error('Sender account not found: ' + tx.from.toString())
223
    }
224
225
    if (fromAccount.get('nonce').gt(tx.nonce)) {
226
      throw new Error(`Invalid nonce: ${fromAccount.get('nonce')} > ${tx.nonce}`)
227
    }
228
229
    fromAccount.set('nonce', fromAccount.get('nonce').add(new U256(1)))
230
231
    let isCreation = false
232
233
    // Special case: contract deployment
234
    if (tx.to.isZero() && (tx.data.length !== 0)) {
235
      console.log('This is a contract deployment transaction')
236
      isCreation = true
237
    }
238
239
    // This cost will not be refunded
240
    let txCost = 21000 + (isCreation ? 32000 : 0)
241
    tx.data.forEach((item) => {
242
      if (item === 0) {
243
        txCost += 4
244
      } else {
245
        txCost += 68
246
      }
247
    })
248
249
    if (tx.gasLimit.lt(new U256(txCost))) {
250
      throw new Error(`Minimum transaction gas limit not met: ${txCost}`)
251
    }
252
253
    if (fromAccount.get('balance').lt(tx.gasLimit.mul(tx.gasPrice))) {
254
      throw new Error(`Insufficient account balance: ${fromAccount.get('balance').toString()} < ${tx.gasLimit.mul(tx.gasPrice).toString()}`)
255
    }
256
257
    // deduct gasLimit * gasPrice from sender
258
    fromAccount.set('balance', fromAccount.get('balance').sub(tx.gasLimit.mul(tx.gasPrice)))
259
260
    const handler = isCreation ? this.createHandler.bind(this) : this.callHandler.bind(this)
261
    let ret = handler({
262
      to: tx.to,
263
      from: tx.from,
264
      gasLimit: tx.gasLimit - txCost,
265
      value: tx.value,
266
      data: tx.data
267
    })
268
269
    // refund unused gas
270
    if (ret.executionOutcome === 1) {
271
      fromAccount.set('balance', fromAccount.get('balance').add(tx.gasPrice.mul(ret.gasLeft.add(ret.gasRefund))))
272
    }
273
274
    // save new state?
275
276
    return {
277
      executionOutcome: ret.executionOutcome,
278
      accountCreated: isCreation ? ret.accountCreated : undefined,
279
      returnValue: isCreation ? undefined : ret.returnValue,
280
      gasLeft: ret.gasLeft,
281
      logs: ret.logs
282
    }
283
  }
284
285
  // run block; the block message handler
286
  runBlock (block, environment = new Environment()) {
287
    // verify block then run each tx
288
    block.tx.forEach((tx) => {
289
      this.runTx(tx, environment)
290
    })
291
  }
292
293
  // run blockchain
294
  // runBlockchain () {}
295
}
296