path: root/ethchain/vm.go

package ethchain

import (
    _ "bytes"
    "fmt"
    "github.com/ethereum/eth-go/ethutil"
    _ "github.com/obscuren/secp256k1-go"
    _ "math"
    "math/big"
)

var (
    GasStep    = big.NewInt(1)
    GasSha     = big.NewInt(20)
    GasSLoad   = big.NewInt(20)
    GasSStore  = big.NewInt(100)
    GasBalance = big.NewInt(20)
    GasCreate  = big.NewInt(100)
    GasCall    = big.NewInt(20)
    GasMemory  = big.NewInt(1)
)

type Vm struct {
    txPool *TxPool
    // Stack for processing contracts
    stack *Stack
    // non-persistent key/value memory storage
    mem map[string]*big.Int

    vars RuntimeVars

    state *State
}

type RuntimeVars struct {
    Origin      []byte
    BlockNumber uint64
    PrevHash    []byte
    Coinbase    []byte
    Time        int64
    Diff        *big.Int
    TxData      []string
}

func NewVm(state *State, vars RuntimeVars) *Vm {
    return &Vm{vars: vars, state: state}
}

var Pow256 = ethutil.BigPow(2, 256)

func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) []byte {
    // If the amount of gas supplied is less equal to 0
    if closure.Gas.Cmp(big.NewInt(0)) <= 0 {
        // TODO Do something
    }

    // Memory for the current closure
    mem := &Memory{}
    // New stack (should this be shared?)
    stack := NewStack()
    // Instruction pointer
    pc := big.NewInt(0)
    // Current step count
    step := 0
    // The base for all big integer arithmetic
    base := new(big.Int)

    /*
        if ethutil.Config.Debug {
            ethutil.Config.Log.Debugf("#   op\n")
        }
    */

    for {
        step++
        // Get the memory location of pc
        val := closure.Get(pc)
        // Get the opcode (it must be an opcode!)
        op := OpCode(val.Uint())
        /*
            if ethutil.Config.Debug {
                ethutil.Config.Log.Debugf("%-3d %-4s", pc, op.String())
            }
        */

        // TODO Get each instruction cost properly
        gas := new(big.Int)
        useGas := func(amount *big.Int) {
            gas.Add(gas, amount)
        }

        switch op {
        case oSHA3:
            useGas(GasSha)
        case oSLOAD:
            useGas(GasSLoad)
        case oSSTORE:
            var mult *big.Int
            y, x := stack.Peekn()
            val := closure.GetMem(x)
            if val.IsEmpty() && len(y.Bytes()) > 0 {
                mult = ethutil.Big2
            } else if !val.IsEmpty() && len(y.Bytes()) == 0 {
                mult = ethutil.Big0
            } else {
                mult = ethutil.Big1
            }
            useGas(base.Mul(mult, GasSStore))
        case oBALANCE:
            useGas(GasBalance)
        case oCREATE:
            useGas(GasCreate)
        case oCALL:
            useGas(GasCall)
        case oMLOAD, oMSIZE, oMSTORE8, oMSTORE:
            useGas(GasMemory)
        default:
            useGas(GasStep)
        }

        if closure.Gas.Cmp(gas) < 0 {
            ethutil.Config.Log.Debugln("Insufficient gas", closure.Gas, gas)

            return closure.Return(nil)
        }

        switch op {
        case oLOG:
            stack.Print()
            mem.Print()
        case oSTOP: // Stop the closure
            return closure.Return(nil)

        // 0x20 range
        case oADD:
            x, y := stack.Popn()
            // (x + y) % 2 ** 256
            base.Add(x, y)
            base.Mod(base, Pow256)
            // Pop result back on the stack
            stack.Push(base)
        case oSUB:
            x, y := stack.Popn()
            // (x - y) % 2 ** 256
            base.Sub(x, y)
            base.Mod(base, Pow256)
            // Pop result back on the stack
            stack.Push(base)
        case oMUL:
            x, y := stack.Popn()
            // (x * y) % 2 ** 256
            base.Mul(x, y)
            base.Mod(base, Pow256)
            // Pop result back on the stack
            stack.Push(base)
        case oDIV:
            x, y := stack.Popn()
            // floor(x / y)
            base.Div(x, y)
            // Pop result back on the stack
            stack.Push(base)
        case oSDIV:
            x, y := stack.Popn()
            // n > 2**255
            if x.Cmp(Pow256) > 0 {
                x.Sub(Pow256, x)
            }
            if y.Cmp(Pow256) > 0 {
                y.Sub(Pow256, y)
            }
            z := new(big.Int)
            z.Div(x, y)
            if z.Cmp(Pow256) > 0 {
                z.Sub(Pow256, z)
            }
            // Push result on to the stack
            stack.Push(z)
        case oMOD:
            x, y := stack.Popn()
            base.Mod(x, y)
            stack.Push(base)
        case oSMOD:
            x, y := stack.Popn()
            // n > 2**255
            if x.Cmp(Pow256) > 0 {
                x.Sub(Pow256, x)
            }
            if y.Cmp(Pow256) > 0 {
                y.Sub(Pow256, y)
            }
            z := new(big.Int)
            z.Mod(x, y)
            if z.Cmp(Pow256) > 0 {
                z.Sub(Pow256, z)
            }
            // Push result on to the stack
            stack.Push(z)
        case oEXP:
            x, y := stack.Popn()
            base.Exp(x, y, Pow256)

            stack.Push(base)
        case oNEG:
            base.Sub(Pow256, stack.Pop())
            stack.Push(base)
        case oLT:
            x, y := stack.Popn()
            // x < y
            if x.Cmp(y) < 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case oGT:
            x, y := stack.Popn()
            // x > y
            if x.Cmp(y) > 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case oEQ:
            x, y := stack.Popn()
            // x == y
            if x.Cmp(y) == 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case oNOT:
            x := stack.Pop()
            if x.Cmp(ethutil.BigFalse) == 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }

        // 0x10 range
        case oAND:
            x, y := stack.Popn()
            if (x.Cmp(ethutil.BigTrue) >= 0) && (y.Cmp(ethutil.BigTrue) >= 0) {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }

        case oOR:
            x, y := stack.Popn()
            if (x.Cmp(ethutil.BigInt0) >= 0) || (y.Cmp(ethutil.BigInt0) >= 0) {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case oXOR:
            x, y := stack.Popn()
            stack.Push(base.Xor(x, y))
        case oBYTE:
            val, th := stack.Popn()
            if th.Cmp(big.NewInt(32)) < 0 {
                stack.Push(big.NewInt(int64(len(val.Bytes())-1) - th.Int64()))
            } else {
                stack.Push(ethutil.BigFalse)
            }

        // 0x20 range
        case oSHA3:
            size, offset := stack.Popn()
            data := mem.Get(offset.Int64(), size.Int64())

            stack.Push(ethutil.BigD(data))
        // 0x30 range
        case oADDRESS:
            stack.Push(ethutil.BigD(closure.Object().Address()))
        case oBALANCE:
            stack.Push(closure.Value)
        case oORIGIN:
            stack.Push(ethutil.BigD(vm.vars.Origin))
        case oCALLER:
            stack.Push(ethutil.BigD(closure.Callee().Address()))
        case oCALLVALUE:
            // FIXME: Original value of the call, not the current value
            stack.Push(closure.Value)
        case oCALLDATA:
            offset := stack.Pop()
            mem.Set(offset.Int64(), int64(len(closure.Args)), closure.Args)
        case oCALLDATASIZE:
            stack.Push(big.NewInt(int64(len(closure.Args))))
        case oGASPRICE:
            // TODO

        // 0x40 range
        case oPREVHASH:
            stack.Push(ethutil.BigD(vm.vars.PrevHash))
        case oCOINBASE:
            stack.Push(ethutil.BigD(vm.vars.Coinbase))
        case oTIMESTAMP:
            stack.Push(big.NewInt(vm.vars.Time))
        case oNUMBER:
            stack.Push(big.NewInt(int64(vm.vars.BlockNumber)))
        case oDIFFICULTY:
            stack.Push(vm.vars.Diff)
        case oGASLIMIT:
            // TODO

        // 0x50 range
        case oPUSH: // Push PC+1 on to the stack
            pc.Add(pc, ethutil.Big1)
            data := closure.Gets(pc, big.NewInt(32))
            val := ethutil.BigD(data.Bytes())

            // Push value to stack
            stack.Push(val)

            pc.Add(pc, big.NewInt(31))
            step++
        case oPUSH20:
            pc.Add(pc, ethutil.Big1)
            data := closure.Gets(pc, big.NewInt(20))
            val := ethutil.BigD(data.Bytes())

            // Push value to stack
            stack.Push(val)

            pc.Add(pc, big.NewInt(19))
            step++
        case oPOP:
            stack.Pop()
        case oDUP:
            stack.Push(stack.Peek())
        case oSWAP:
            x, y := stack.Popn()
            stack.Push(y)
            stack.Push(x)
        case oMLOAD:
            offset := stack.Pop()
            stack.Push(ethutil.BigD(mem.Get(offset.Int64(), 32)))
        case oMSTORE: // Store the value at stack top-1 in to memory at location stack top
            // Pop value of the stack
            val, mStart := stack.Popn()
            mem.Set(mStart.Int64(), 32, ethutil.BigToBytes(val, 256))
        case oMSTORE8:
            val, mStart := stack.Popn()
            base.And(val, new(big.Int).SetInt64(0xff))
            mem.Set(mStart.Int64(), 32, ethutil.BigToBytes(base, 256))
        case oSLOAD:
            loc := stack.Pop()
            val := closure.GetMem(loc)
            stack.Push(val.BigInt())
        case oSSTORE:
            val, loc := stack.Popn()
            closure.SetMem(loc, ethutil.NewValue(val))
        case oJUMP:
            pc = stack.Pop()
        case oJUMPI:
            cond, pos := stack.Popn()
            if cond.Cmp(ethutil.BigTrue) == 0 {
                pc = pos
            }
        case oPC:
            stack.Push(pc)
        case oMSIZE:
            stack.Push(big.NewInt(int64(mem.Len())))
        // 0x60 range
        case oCALL:
            // Closure addr
            addr := stack.Pop()
            // Pop gas and value of the stack.
            gas, value := stack.Popn()
            // Pop input size and offset
            inSize, inOffset := stack.Popn()
            // Pop return size and offset
            retSize, retOffset := stack.Popn()
            // Get the arguments from the memory
            args := mem.Get(inOffset.Int64(), inSize.Int64())
            // Fetch the contract which will serve as the closure body
            contract := vm.state.GetContract(addr.Bytes())
            // Create a new callable closure
            closure := NewClosure(closure, contract, contract.script, vm.state, gas, value)
            // Executer the closure and get the return value (if any)
            ret := closure.Call(vm, args, hook)

            mem.Set(retOffset.Int64(), retSize.Int64(), ret)
        case oRETURN:
            size, offset := stack.Popn()
            ret := mem.Get(offset.Int64(), size.Int64())

            return closure.Return(ret)
        case oSUICIDE:
            /*
                recAddr := stack.Pop().Bytes()
                // Purge all memory
                deletedMemory := contract.state.Purge()
                // Add refunds to the pop'ed address
                refund := new(big.Int).Mul(StoreFee, big.NewInt(int64(deletedMemory)))
                account := state.GetAccount(recAddr)
                account.Amount.Add(account.Amount, refund)
                // Update the refunding address
                state.UpdateAccount(recAddr, account)
                // Delete the contract
                state.trie.Update(string(addr), "")

                ethutil.Config.Log.Debugf("(%d) => %x\n", deletedMemory, recAddr)
                break out
            */
        default:
            ethutil.Config.Log.Debugf("Invalid opcode %x\n", op)

            return closure.Return(nil)
        }

        pc.Add(pc, ethutil.Big1)

        if hook != nil {
            hook(step-1, op, mem, stack)
        }
    }
}

func Disassemble(script []byte) (asm []string) {
    pc := new(big.Int)
    for {
        if pc.Cmp(big.NewInt(int64(len(script)))) >= 0 {
            return
        }

        // Get the memory location of pc
        val := script[pc.Int64()]
        // Get the opcode (it must be an opcode!)
        op := OpCode(val)

        asm = append(asm, fmt.Sprintf("%v", op))

        switch op {
        case oPUSH: // Push PC+1 on to the stack
            pc.Add(pc, ethutil.Big1)
            data := script[pc.Int64() : pc.Int64()+32]
            val := ethutil.BigD(data)

            var b []byte
            if val.Int64() == 0 {
                b = []byte{0}
            } else {
                b = val.Bytes()
            }

            asm = append(asm, fmt.Sprintf("0x%x", b))

            pc.Add(pc, big.NewInt(31))
        case oPUSH20:
            pc.Add(pc, ethutil.Big1)
            data := script[pc.Int64() : pc.Int64()+20]
            val := ethutil.BigD(data)
            var b []byte
            if val.Int64() == 0 {
                b = []byte{0}
            } else {
                b = val.Bytes()
            }

            asm = append(asm, fmt.Sprintf("0x%x", b))

            pc.Add(pc, big.NewInt(19))
        }

        pc.Add(pc, ethutil.Big1)
    }

    return
}