aboutsummaryrefslogtreecommitdiff
path: root/core/vm/interpreter.go
blob: e23896ab9959e3461251d4aed2dee57f93313e10 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"fmt"
	"hash"
	"sync/atomic"

	"github.com/ava-labs/go-ethereum/common"
	"github.com/ava-labs/go-ethereum/common/math"
	"github.com/ava-labs/go-ethereum/log"
)

var (
	BuiltinAddr = common.Address{
		1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	}
)

// Config are the configuration options for the Interpreter
type Config struct {
	Debug                   bool   // Enables debugging
	Tracer                  Tracer // Opcode logger
	NoRecursion             bool   // Disables call, callcode, delegate call and create
	EnablePreimageRecording bool   // Enables recording of SHA3/keccak preimages

	JumpTable [256]operation // EVM instruction table, automatically populated if unset

	EWASMInterpreter string // External EWASM interpreter options
	EVMInterpreter   string // External EVM interpreter options

	ExtraEips []int // Additional EIPS that are to be enabled
}

// Interpreter is used to run Ethereum based contracts and will utilise the
// passed environment to query external sources for state information.
// The Interpreter will run the byte code VM based on the passed
// configuration.
type Interpreter interface {
	// Run loops and evaluates the contract's code with the given input data and returns
	// the return byte-slice and an error if one occurred.
	Run(contract *Contract, input []byte, static bool) ([]byte, error)
	// CanRun tells if the contract, passed as an argument, can be
	// run by the current interpreter. This is meant so that the
	// caller can do something like:
	//
	// ```golang
	// for _, interpreter := range interpreters {
	//   if interpreter.CanRun(contract.code) {
	//     interpreter.Run(contract.code, input)
	//   }
	// }
	// ```
	CanRun([]byte) bool
}

// keccakState wraps sha3.state. In addition to the usual hash methods, it also supports
// Read to get a variable amount of data from the hash state. Read is faster than Sum
// because it doesn't copy the internal state, but also modifies the internal state.
type keccakState interface {
	hash.Hash
	Read([]byte) (int, error)
}

// EVMInterpreter represents an EVM interpreter
type EVMInterpreter struct {
	evm *EVM
	cfg Config

	intPool *intPool

	hasher    keccakState // Keccak256 hasher instance shared across opcodes
	hasherBuf common.Hash // Keccak256 hasher result array shared aross opcodes

	readOnly   bool   // Whether to throw on stateful modifications
	returnData []byte // Last CALL's return data for subsequent reuse
}

// NewEVMInterpreter returns a new instance of the Interpreter.
func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
	// We use the STOP instruction whether to see
	// the jump table was initialised. If it was not
	// we'll set the default jump table.
	if !cfg.JumpTable[STOP].valid {
		var jt JumpTable
		switch {
		case evm.chainRules.IsIstanbul:
			jt = istanbulInstructionSet
		case evm.chainRules.IsConstantinople:
			jt = constantinopleInstructionSet
		case evm.chainRules.IsByzantium:
			jt = byzantiumInstructionSet
		case evm.chainRules.IsEIP158:
			jt = spuriousDragonInstructionSet
		case evm.chainRules.IsEIP150:
			jt = tangerineWhistleInstructionSet
		case evm.chainRules.IsHomestead:
			jt = homesteadInstructionSet
		default:
			jt = frontierInstructionSet
		}
		for i, eip := range cfg.ExtraEips {
			if err := EnableEIP(eip, &jt); err != nil {
				// Disable it, so caller can check if it's activated or not
				cfg.ExtraEips = append(cfg.ExtraEips[:i], cfg.ExtraEips[i+1:]...)
				log.Error("EIP activation failed", "eip", eip, "error", err)
			}
		}
		cfg.JumpTable = jt
	}

	return &EVMInterpreter{
		evm: evm,
		cfg: cfg,
	}
}

// Run loops and evaluates the contract's code with the given input data and returns
// the return byte-slice and an error if one occurred.
//
// It's important to note that any errors returned by the interpreter should be
// considered a revert-and-consume-all-gas operation except for
// errExecutionReverted which means revert-and-keep-gas-left.
func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error) {
	if contract.Address() == BuiltinAddr {
		self := AccountRef(contract.Caller())
		if _, ok := contract.caller.(*Contract); ok {
			contract = contract.AsDelegate()
		}
		contract.self = self
	}
	if in.intPool == nil {
		in.intPool = poolOfIntPools.get()
		defer func() {
			poolOfIntPools.put(in.intPool)
			in.intPool = nil
		}()
	}

	// Increment the call depth which is restricted to 1024
	in.evm.depth++
	defer func() { in.evm.depth-- }()

	// Make sure the readOnly is only set if we aren't in readOnly yet.
	// This makes also sure that the readOnly flag isn't removed for child calls.
	if readOnly && !in.readOnly {
		in.readOnly = true
		defer func() { in.readOnly = false }()
	}

	// Reset the previous call's return data. It's unimportant to preserve the old buffer
	// as every returning call will return new data anyway.
	in.returnData = nil

	// Don't bother with the execution if there's no code.
	if len(contract.Code) == 0 {
		return nil, nil
	}

	var (
		op    OpCode        // current opcode
		mem   = NewMemory() // bound memory
		stack = newstack()  // local stack
		// For optimisation reason we're using uint64 as the program counter.
		// It's theoretically possible to go above 2^64. The YP defines the PC
		// to be uint256. Practically much less so feasible.
		pc   = uint64(0) // program counter
		cost uint64
		// copies used by tracer
		pcCopy  uint64 // needed for the deferred Tracer
		gasCopy uint64 // for Tracer to log gas remaining before execution
		logged  bool   // deferred Tracer should ignore already logged steps
		res     []byte // result of the opcode execution function
	)
	contract.Input = input

	// Reclaim the stack as an int pool when the execution stops
	defer func() { in.intPool.put(stack.data...) }()

	if in.cfg.Debug {
		defer func() {
			if err != nil {
				if !logged {
					in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
				} else {
					in.cfg.Tracer.CaptureFault(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
				}
			}
		}()
	}
	// The Interpreter main run loop (contextual). This loop runs until either an
	// explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during
	// the execution of one of the operations or until the done flag is set by the
	// parent context.
	for atomic.LoadInt32(&in.evm.abort) == 0 {
		if in.cfg.Debug {
			// Capture pre-execution values for tracing.
			logged, pcCopy, gasCopy = false, pc, contract.Gas
		}

		// Get the operation from the jump table and validate the stack to ensure there are
		// enough stack items available to perform the operation.
		op = contract.GetOp(pc)
		operation := in.cfg.JumpTable[op]
		if !operation.valid {
			return nil, fmt.Errorf("invalid opcode 0x%x", int(op))
		}
		// Validate stack
		if sLen := stack.len(); sLen < operation.minStack {
			return nil, fmt.Errorf("stack underflow (%d <=> %d)", sLen, operation.minStack)
		} else if sLen > operation.maxStack {
			return nil, fmt.Errorf("stack limit reached %d (%d)", sLen, operation.maxStack)
		}
		// If the operation is valid, enforce and write restrictions
		if in.readOnly && in.evm.chainRules.IsByzantium {
			// If the interpreter is operating in readonly mode, make sure no
			// state-modifying operation is performed. The 3rd stack item
			// for a call operation is the value. Transferring value from one
			// account to the others means the state is modified and should also
			// return with an error.
			if operation.writes || ((op == CALL || op == CALLEX) && stack.Back(2).Sign() != 0) {
				return nil, errWriteProtection
			}
		}
		// Static portion of gas
		cost = operation.constantGas // For tracing
		if !contract.UseGas(operation.constantGas) {
			return nil, ErrOutOfGas
		}

		var memorySize uint64
		// calculate the new memory size and expand the memory to fit
		// the operation
		// Memory check needs to be done prior to evaluating the dynamic gas portion,
		// to detect calculation overflows
		if operation.memorySize != nil {
			memSize, overflow := operation.memorySize(stack)
			if overflow {
				return nil, errGasUintOverflow
			}
			// memory is expanded in words of 32 bytes. Gas
			// is also calculated in words.
			if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow {
				return nil, errGasUintOverflow
			}
		}
		// Dynamic portion of gas
		// consume the gas and return an error if not enough gas is available.
		// cost is explicitly set so that the capture state defer method can get the proper cost
		if operation.dynamicGas != nil {
			var dynamicCost uint64
			dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize)
			cost += dynamicCost // total cost, for debug tracing
			if err != nil || !contract.UseGas(dynamicCost) {
				return nil, ErrOutOfGas
			}
		}
		if memorySize > 0 {
			mem.Resize(memorySize)
		}

		if in.cfg.Debug {
			in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
			logged = true
		}

		// execute the operation
		res, err = operation.execute(&pc, in, contract, mem, stack)
		// verifyPool is a build flag. Pool verification makes sure the integrity
		// of the integer pool by comparing values to a default value.
		if verifyPool {
			verifyIntegerPool(in.intPool)
		}
		// if the operation clears the return data (e.g. it has returning data)
		// set the last return to the result of the operation.
		if operation.returns {
			in.returnData = res
		}

		switch {
		case err != nil:
			return nil, err
		case operation.reverts:
			return res, errExecutionReverted
		case operation.halts:
			return res, nil
		case !operation.jumps:
			pc++
		}
	}
	return nil, nil
}

// CanRun tells if the contract, passed as an argument, can be
// run by the current interpreter.
func (in *EVMInterpreter) CanRun(code []byte) bool {
	return true
}