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255 lines
10 KiB
255 lines
10 KiB
// Copyright 2024 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"errors"
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"fmt"
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"io"
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)
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// Below are all possible errors that can occur during validation of
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// EOF containers.
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var (
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errInvalidMagic = errors.New("invalid magic")
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errUndefinedInstruction = errors.New("undefined instruction")
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errTruncatedImmediate = errors.New("truncated immediate")
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errInvalidSectionArgument = errors.New("invalid section argument")
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errInvalidCallArgument = errors.New("callf into non-returning section")
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errInvalidDataloadNArgument = errors.New("invalid dataloadN argument")
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errInvalidJumpDest = errors.New("invalid jump destination")
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errInvalidBackwardJump = errors.New("invalid backward jump")
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errInvalidOutputs = errors.New("invalid number of outputs")
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errInvalidMaxStackHeight = errors.New("invalid max stack height")
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errInvalidCodeTermination = errors.New("invalid code termination")
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errEOFCreateWithTruncatedSection = errors.New("eofcreate with truncated section")
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errOrphanedSubcontainer = errors.New("subcontainer not referenced at all")
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errIncompatibleContainerKind = errors.New("incompatible container kind")
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errStopAndReturnContract = errors.New("Stop/Return and Returncontract in the same code section")
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errStopInInitCode = errors.New("initcode contains a RETURN or STOP opcode")
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errTruncatedTopLevelContainer = errors.New("truncated top level container")
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errUnreachableCode = errors.New("unreachable code")
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errInvalidNonReturningFlag = errors.New("invalid non-returning flag, bad RETF")
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errInvalidVersion = errors.New("invalid version")
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errMissingTypeHeader = errors.New("missing type header")
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errInvalidTypeSize = errors.New("invalid type section size")
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errMissingCodeHeader = errors.New("missing code header")
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errInvalidCodeSize = errors.New("invalid code size")
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errInvalidContainerSectionSize = errors.New("invalid container section size")
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errMissingDataHeader = errors.New("missing data header")
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errMissingTerminator = errors.New("missing header terminator")
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errTooManyInputs = errors.New("invalid type content, too many inputs")
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errTooManyOutputs = errors.New("invalid type content, too many outputs")
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errInvalidSection0Type = errors.New("invalid section 0 type, input and output should be zero and non-returning (0x80)")
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errTooLargeMaxStackHeight = errors.New("invalid type content, max stack height exceeds limit")
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errInvalidContainerSize = errors.New("invalid container size")
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)
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const (
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notRefByEither = iota
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refByReturnContract
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refByEOFCreate
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)
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type validationResult struct {
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visitedCode map[int]struct{}
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visitedSubContainers map[int]int
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isInitCode bool
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isRuntime bool
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}
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// validateCode validates the code parameter against the EOF v1 validity requirements.
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func validateCode(code []byte, section int, container *Container, jt *JumpTable, isInitCode bool) (*validationResult, error) {
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var (
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i = 0
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// Tracks the number of actual instructions in the code (e.g.
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// non-immediate values). This is used at the end to determine
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// if each instruction is reachable.
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count = 0
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op OpCode
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analysis bitvec
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visitedCode map[int]struct{}
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visitedSubcontainers map[int]int
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hasReturnContract bool
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hasStop bool
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)
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// This loop visits every single instruction and verifies:
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// * if the instruction is valid for the given jump table.
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// * if the instruction has an immediate value, it is not truncated.
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// * if performing a relative jump, all jump destinations are valid.
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// * if changing code sections, the new code section index is valid and
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// will not cause a stack overflow.
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for i < len(code) {
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count++
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op = OpCode(code[i])
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if jt[op].undefined {
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return nil, fmt.Errorf("%w: op %s, pos %d", errUndefinedInstruction, op, i)
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}
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size := int(immediates[op])
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if size != 0 && len(code) <= i+size {
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return nil, fmt.Errorf("%w: op %s, pos %d", errTruncatedImmediate, op, i)
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}
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switch op {
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case RJUMP, RJUMPI:
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if err := checkDest(code, &analysis, i+1, i+3, len(code)); err != nil {
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return nil, err
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}
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case RJUMPV:
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max_size := int(code[i+1])
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length := max_size + 1
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if len(code) <= i+length {
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return nil, fmt.Errorf("%w: jump table truncated, op %s, pos %d", errTruncatedImmediate, op, i)
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}
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offset := i + 2
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for j := 0; j < length; j++ {
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if err := checkDest(code, &analysis, offset+j*2, offset+(length*2), len(code)); err != nil {
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return nil, err
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}
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}
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i += 2 * max_size
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case CALLF:
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arg, _ := parseUint16(code[i+1:])
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if arg >= len(container.types) {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errInvalidSectionArgument, arg, len(container.types), i)
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}
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if container.types[arg].outputs == 0x80 {
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return nil, fmt.Errorf("%w: section %v", errInvalidCallArgument, arg)
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}
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if visitedCode == nil {
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visitedCode = make(map[int]struct{})
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}
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visitedCode[arg] = struct{}{}
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case JUMPF:
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arg, _ := parseUint16(code[i+1:])
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if arg >= len(container.types) {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errInvalidSectionArgument, arg, len(container.types), i)
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}
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if container.types[arg].outputs != 0x80 && container.types[arg].outputs > container.types[section].outputs {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errInvalidOutputs, arg, len(container.types), i)
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}
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if visitedCode == nil {
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visitedCode = make(map[int]struct{})
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}
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visitedCode[arg] = struct{}{}
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case DATALOADN:
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arg, _ := parseUint16(code[i+1:])
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// TODO why are we checking this? We should just pad
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if arg+32 > len(container.data) {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errInvalidDataloadNArgument, arg, len(container.data), i)
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}
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case RETURNCONTRACT:
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if !isInitCode {
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return nil, errIncompatibleContainerKind
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}
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arg := int(code[i+1])
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if arg >= len(container.subContainers) {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errUnreachableCode, arg, len(container.subContainers), i)
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}
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if visitedSubcontainers == nil {
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visitedSubcontainers = make(map[int]int)
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}
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// We need to store per subcontainer how it was referenced
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if v, ok := visitedSubcontainers[arg]; ok && v != refByReturnContract {
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return nil, fmt.Errorf("section already referenced, arg :%d", arg)
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}
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if hasStop {
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return nil, errStopAndReturnContract
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}
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hasReturnContract = true
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visitedSubcontainers[arg] = refByReturnContract
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case EOFCREATE:
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arg := int(code[i+1])
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if arg >= len(container.subContainers) {
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return nil, fmt.Errorf("%w: arg %d, last %d, pos %d", errUnreachableCode, arg, len(container.subContainers), i)
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}
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if ct := container.subContainers[arg]; len(ct.data) != ct.dataSize {
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return nil, fmt.Errorf("%w: container %d, have %d, claimed %d, pos %d", errEOFCreateWithTruncatedSection, arg, len(ct.data), ct.dataSize, i)
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}
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if visitedSubcontainers == nil {
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visitedSubcontainers = make(map[int]int)
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}
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// We need to store per subcontainer how it was referenced
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if v, ok := visitedSubcontainers[arg]; ok && v != refByEOFCreate {
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return nil, fmt.Errorf("section already referenced, arg :%d", arg)
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}
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visitedSubcontainers[arg] = refByEOFCreate
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case STOP, RETURN:
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if isInitCode {
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return nil, errStopInInitCode
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}
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if hasReturnContract {
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return nil, errStopAndReturnContract
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}
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hasStop = true
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}
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i += size + 1
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}
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// Code sections may not "fall through" and require proper termination.
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// Therefore, the last instruction must be considered terminal or RJUMP.
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if !terminals[op] && op != RJUMP {
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return nil, fmt.Errorf("%w: end with %s, pos %d", errInvalidCodeTermination, op, i)
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}
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if paths, err := validateControlFlow(code, section, container.types, jt); err != nil {
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return nil, err
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} else if paths != count {
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// TODO(matt): return actual position of unreachable code
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return nil, errUnreachableCode
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}
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return &validationResult{
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visitedCode: visitedCode,
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visitedSubContainers: visitedSubcontainers,
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isInitCode: hasReturnContract,
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isRuntime: hasStop,
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}, nil
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}
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// checkDest parses a relative offset at code[0:2] and checks if it is a valid jump destination.
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func checkDest(code []byte, analysis *bitvec, imm, from, length int) error {
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if len(code) < imm+2 {
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return io.ErrUnexpectedEOF
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}
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if analysis != nil && *analysis == nil {
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*analysis = eofCodeBitmap(code)
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}
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offset := parseInt16(code[imm:])
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dest := from + offset
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if dest < 0 || dest >= length {
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return fmt.Errorf("%w: out-of-bounds offset: offset %d, dest %d, pos %d", errInvalidJumpDest, offset, dest, imm)
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}
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if !analysis.codeSegment(uint64(dest)) {
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return fmt.Errorf("%w: offset into immediate: offset %d, dest %d, pos %d", errInvalidJumpDest, offset, dest, imm)
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}
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return nil
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}
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//// disasm is a helper utility to show a sequence of comma-separated operations,
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//// with immediates shown inline,
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//// e.g: PUSH1(0x00),EOFCREATE(0x00),
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//func disasm(code []byte) string {
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// var ops []string
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// for i := 0; i < len(code); i++ {
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// var op string
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// if args := immediates[code[i]]; args > 0 {
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// op = fmt.Sprintf("%v(%#x)", OpCode(code[i]).String(), code[i+1:i+1+int(args)])
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// i += int(args)
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// } else {
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// op = OpCode(code[i]).String()
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// }
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// ops = append(ops, op)
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// }
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// return strings.Join(ops, ",")
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//}
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