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('./address.js')
23
const U256 = require('./u256.js')
24
const Utils = require('./utils.js')
25
const Transaction = require('./transaction.js')
26
const Precompile = require('./precompile.js')
27
28
const meteringContract = new Address('0x000000000000000000000000000000000000000A')
29
const transcompilerContract = new Address('0x000000000000000000000000000000000000000B')
30
31
module.exports = class Kernel {
32
  // runs some code in the VM
33
  constructor (environment = new Environment()) {
34
    this.environment = environment
35
  }
36
37
  // handles running code.
38
  // NOTE: it assumes that wasm will raise an exception if something went wrong,
39
  //       otherwise execution succeeded
40
  codeHandler (code, ethInterface = new Interface(new Environment())) {
41
    const debugInterface = new DebugInterface(ethInterface.environment)
42
43
    const instance = Wasm.instantiateModule(code, {
44
      'ethereum': ethInterface.exportTable,
45
      'debug': debugInterface.exportTable,
46
47
      // export this for Rust
48
      // FIXME: remove once Rust has proper imports, see https://github.com/ethereum/evm2.0-design/issues/15
49
      'spectest': ethInterface.exportTable,
50
51
      // export this for Binaryen
52
      // FIXME: remove once C has proper imports, see https://github.com/ethereum/evm2.0-design/issues/16
53
      'env': ethInterface.exportTable
54
    })
55
56
    ethInterface.setModule(instance)
57
    debugInterface.setModule(instance)
58
59
    if (instance.exports.main) {
60
      instance.exports.main()
61
    }
62
    return instance
63
  }
64
65
  // loads code from the merkle trie and delegates the message
66
  // Detects if code is EVM or WASM
67
  // Detects if the code injection is needed
68
  // Detects if transcompilation is needed
69
  callHandler (call) {
70
    // FIXME: this is here until these two contracts are compiled to WASM
71
    // The two special contracts (precompiles now, but will be real ones later)
72
    if (call.to.equals(meteringContract)) {
73
      return Precompile.meteringInjector(call)
74
    } else if (call.to.equals(transcompilerContract)) {
75
      return Precompile.transcompiler(call)
76
    }
77
78
    let account = this.environment.state.get(call.to.toString())
79
    if (!account) {
80
      throw new Error('Account not found: ' + call.to.toString())
81
    }
82
83
    let code = Uint8Array.from(account.get('code'))
84
    if (code.length === 0) {
85
      throw new Error('Contract not found')
86
    }
87
88
    if (!Utils.isWASMCode(code)) {
89
      // throw new Error('Not an eWASM contract')
90
91
      // Transcompile code
92
      code = this.callHandler({ to: transcompilerContract, data: code }).returnValue
93
    }
94
95
    // creats a new Kernel
96
    const environment = new Environment()
97
    environment.parent = this
98
99
    // copy the transaction details
100
    environment.code = code
101
    environment.address = call.to
102
    // FIXME: make distinction between origin and caller
103
    environment.origin = call.from
104
    environment.caller = call.from
105
    environment.callData = call.data
106
    environment.callValue = call.value
107
    environment.gasLeft = call.gasLimit
108
109
    // environment.setCallHandler(this.callHandler)
110
    // environment.setCreateHandler(this.createHandler)
111
112
    const kernel = new Kernel(this, environment)
113
    kernel.codeHandler(code, new Interface(environment))
114
115
    // generate new stateroot
116
    // this.environment.state.set(address, { stateRoot: stateRoot })
117
118
    return {
119
      executionOutcome: 1, // success
120
      gasLeft: new U256(environment.gasLeft),
121
      gasRefund: new U256(environment.gasRefund),
122
      returnValue: environment.returnValue,
123
      selfDestructAddress: environment.selfDestructAddress,
124
      logs: environment.logs
125
    }
126
  }
127
128
  createHandler (create) {
129
    let code = create.data
130
131
    // Inject metering
132
    if (Utils.isWASMCode(code)) {
133
      code = this.callHandler({ to: meteringContract, data: code }).returnValue
134
    }
135
136
    let address = Utils.newAccountAddress(create.from, code)
137
138
    this.environment.addAccount(address.toString(), {
139
      balance: create.value,
140
      code: code
141
    })
142
143
    // Run code and take return value as contract code
144
    code = this.callHandler({ from: create.from, to: address, gasLimit: create.gasLimit }).returnValue
145
146
    this.environment.state.get(address.toString()).set('code', code)
147
148
    return {
149
      accountCreated: address
150
    }
151
  }
152
153
  // run tx; the tx message handler
154
  runTx (tx, environment = new Environment()) {
155
    this.environment = environment
156
157
    if (Buffer.isBuffer(tx) || typeof tx === 'string') {
158
      tx = new Transaction(tx)
159
      if (!tx.valid) {
160
        throw new Error('Invalid transaction signature')
161
      }
162
    }
163
164
    // look up sender
165
    let fromAccount = this.environment.state.get(tx.from.toString())
166
    if (!fromAccount) {
167
      throw new Error('Sender account not found: ' + tx.from.toString())
168
    }
169
170
    if (fromAccount.get('nonce').gt(tx.nonce)) {
171
      throw new Error(`Invalid nonce: ${fromAccount.get('nonce')} > ${tx.nonce}`)
172
    }
173
174
    fromAccount.set('nonce', fromAccount.get('nonce').add(new U256(1)))
175
176
    // Special case: contract deployment
177
    if (tx.to.isZero()) {
178
      if (tx.data.length !== 0) {
179
        console.log('This is a contract deployment transaction')
180
181
        // FIXME: deduct fees
182
183
        return this.createHandler({
184
          from: tx.from,
185
          gasLimit: tx.gasLimit,
186
          value: tx.value,
187
          data: tx.data
188
        })
189
      }
190
    }
191
192
    // deduct gasLimit * gasPrice from sender
193
    if (fromAccount.get('balance').lt(tx.gasLimit.mul(tx.gasPrice))) {
194
      throw new Error(`Insufficient account balance: ${fromAccount.get('balance').toString()} < ${tx.gasLimit.mul(tx.gasPrice).toString()}`)
195
    }
196
197
    fromAccount.set('balance', fromAccount.get('balance').sub(tx.gasLimit.mul(tx.gasPrice)))
198
199
    let ret = this.callHandler({
200
      to: tx.to,
201
      from: tx.from,
202
      gasLimit: tx.gasLimit,
203
      value: tx.value,
204
      data: tx.data
205
    })
206
207
    // refund gas
208
    if (ret.executionOutcome === 1) {
209
      fromAccount.set('balance', fromAccount.get('balance').add(tx.gasPrice.mul(ret.gasLeft.add(ret.gasRefund))))
210
    }
211
212
    // save new state?
213
214
    return {
215
      returnValue: ret.returnValue,
216
      gasLeft: ret.gasLeft,
217
      logs: ret.logs
218
    }
219
  }
220
221
  // run block; the block message handler
222
  runBlock (block, environment = new Environment()) {
223
    // verify block then run each tx
224
    block.tx.forEach((tx) => {
225
      this.runTx(tx, environment)
226
    })
227
  }
228
229
  // run blockchain
230
  // runBlockchain () {}
231
}
232