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snative.go
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snative.go
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// Copyright 2017 Monax Industries Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package vm
import (
"fmt"
"github.com/hyperledger/burrow/common/sanity"
"github.com/hyperledger/burrow/manager/burrow-mint/evm/sha3"
ptypes "github.com/hyperledger/burrow/permission/types"
. "github.com/hyperledger/burrow/word256"
"strings"
"github.com/hyperledger/burrow/manager/burrow-mint/evm/abi"
)
//
// SNative (from 'secure natives') are native (go) contracts that are dispatched
// based on account permissions and can access and modify an account's permissions
//
// Metadata for SNative contract. Acts as a call target from the EVM. Can be
// used to generate bindings in a smart contract languages.
type SNativeContractDescription struct {
// Comment describing purpose of SNative contract and reason for assembling
// the particular functions
Comment string
// Name of the SNative contract
Name string
functionsByID map[abi.FunctionSelector]*SNativeFunctionDescription
functions []*SNativeFunctionDescription
}
// Metadata for SNative functions. Act as call targets for the EVM when
// collected into an SNativeContractDescription. Can be used to generate
// bindings in a smart contract languages.
type SNativeFunctionDescription struct {
// Comment describing function's purpose, parameters, and return value
Comment string
// Function name (used to form signature)
Name string
// Function arguments (used to form signature)
Args []abi.Arg
// Function return value
Return abi.Return
// Permissions required to call function
PermFlag ptypes.PermFlag
// Native function to which calls will be dispatched when a containing
// contract is called with a FunctionSelector matching this NativeContract
F NativeContract
}
func registerSNativeContracts() {
for _, contract := range SNativeContracts() {
registeredNativeContracts[contract.AddressWord256()] = contract.Dispatch
}
}
// Returns a map of all SNative contracts defined indexed by name
func SNativeContracts() map[string]*SNativeContractDescription {
permFlagTypeName := abi.Uint64TypeName
roleTypeName := abi.Bytes32TypeName
contracts := []*SNativeContractDescription{
NewSNativeContract(`
* Interface for managing Secure Native authorizations.
* @dev This interface describes the functions exposed by the SNative permissions layer in burrow.
`,
"Permissions",
&SNativeFunctionDescription{`
* @notice Adds a role to an account
* @param _account account address
* @param _role role name
* @return result whether role was added
`,
"addRole",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_role", roleTypeName),
},
abiReturn("result", abi.BoolTypeName),
ptypes.AddRole,
addRole},
&SNativeFunctionDescription{`
* @notice Removes a role from an account
* @param _account account address
* @param _role role name
* @return result whether role was removed
`,
"removeRole",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_role", roleTypeName),
},
abiReturn("result", abi.BoolTypeName),
ptypes.RmRole,
removeRole},
&SNativeFunctionDescription{`
* @notice Indicates whether an account has a role
* @param _account account address
* @param _role role name
* @return result whether account has role
`,
"hasRole",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_role", roleTypeName),
},
abiReturn("result", abi.BoolTypeName),
ptypes.HasRole,
hasRole},
&SNativeFunctionDescription{`
* @notice Sets the permission flags for an account. Makes them explicitly set (on or off).
* @param _account account address
* @param _permission the base permissions flags to set for the account
* @param _set whether to set or unset the permissions flags at the account level
* @return result the effective permissions flags on the account after the call
`,
"setBase",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_permission", permFlagTypeName),
abiArg("_set", abi.BoolTypeName),
},
abiReturn("result", permFlagTypeName),
ptypes.SetBase,
setBase},
&SNativeFunctionDescription{`
* @notice Unsets the permissions flags for an account. Causes permissions being unset to fall through to global permissions.
* @param _account account address
* @param _permission the permissions flags to unset for the account
* @return result the effective permissions flags on the account after the call
`,
"unsetBase",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_permission", permFlagTypeName)},
abiReturn("result", permFlagTypeName),
ptypes.UnsetBase,
unsetBase},
&SNativeFunctionDescription{`
* @notice Indicates whether an account has a subset of permissions set
* @param _account account address
* @param _permission the permissions flags (mask) to check whether enabled against base permissions for the account
* @return result whether account has the passed permissions flags set
`,
"hasBase",
[]abi.Arg{
abiArg("_account", abi.AddressTypeName),
abiArg("_permission", permFlagTypeName)},
abiReturn("result", abi.BoolTypeName),
ptypes.HasBase,
hasBase},
&SNativeFunctionDescription{`
* @notice Sets the global (default) permissions flags for the entire chain
* @param _permission the permissions flags to set
* @param _set whether to set (or unset) the permissions flags
* @return result the global permissions flags after the call
`,
"setGlobal",
[]abi.Arg{
abiArg("_permission", permFlagTypeName),
abiArg("_set", abi.BoolTypeName)},
abiReturn("result", permFlagTypeName),
ptypes.SetGlobal,
setGlobal},
),
}
contractMap := make(map[string]*SNativeContractDescription, len(contracts))
for _, contract := range contracts {
if _, ok := contractMap[contract.Name]; ok {
// If this happens we have a pseudo compile time error that will be caught
// on native.go init()
panic(fmt.Errorf("Duplicate contract with name %s defined. "+
"Contract names must be unique.", contract.Name))
}
contractMap[contract.Name] = contract
}
return contractMap
}
// Create a new SNative contract description object by passing a comment, name
// and a list of member functions descriptions
func NewSNativeContract(comment, name string,
functions ...*SNativeFunctionDescription) *SNativeContractDescription {
functionsByID := make(map[abi.FunctionSelector]*SNativeFunctionDescription, len(functions))
for _, f := range functions {
fid := f.ID()
otherF, ok := functionsByID[fid]
if ok {
panic(fmt.Errorf("Function with ID %x already defined: %s", fid,
otherF))
}
functionsByID[fid] = f
}
return &SNativeContractDescription{
Comment: comment,
Name: name,
functionsByID: functionsByID,
functions: functions,
}
}
// This function is designed to be called from the EVM once a SNative contract
// has been selected. It is also placed in a registry by registerSNativeContracts
// So it can be looked up by SNative address
func (contract *SNativeContractDescription) Dispatch(appState AppState,
caller *Account, args []byte, gas *int64) (output []byte, err error) {
if len(args) < abi.FunctionSelectorLength {
return nil, fmt.Errorf("SNatives dispatch requires a 4-byte function "+
"identifier but arguments are only %s bytes long", len(args))
}
function, err := contract.FunctionByID(firstFourBytes(args))
if err != nil {
return nil, err
}
remainingArgs := args[abi.FunctionSelectorLength:]
// check if we have permission to call this function
if !HasPermission(appState, caller, function.PermFlag) {
return nil, ErrInvalidPermission{caller.Address, function.Name}
}
// ensure there are enough arguments
if len(remainingArgs) != function.NArgs()*Word256Length {
return nil, fmt.Errorf("%s() takes %d arguments", function.Name,
function.NArgs())
}
// call the function
return function.F(appState, caller, remainingArgs, gas)
}
// We define the address of an SNative contact as the last 20 bytes of the sha3
// hash of its name
func (contract *SNativeContractDescription) Address() abi.Address {
var address abi.Address
hash := sha3.Sha3([]byte(contract.Name))
copy(address[:], hash[len(hash)-abi.AddressLength:])
return address
}
// Get address as a byte slice
func (contract *SNativeContractDescription) AddressBytes() []byte {
address := contract.Address()
return address[:]
}
// Get address as a left-padded Word256
func (contract *SNativeContractDescription) AddressWord256() Word256 {
return LeftPadWord256(contract.AddressBytes())
}
// Get function by calling identifier FunctionSelector
func (contract *SNativeContractDescription) FunctionByID(id abi.FunctionSelector) (*SNativeFunctionDescription, error) {
f, ok := contract.functionsByID[id]
if !ok {
return nil,
fmt.Errorf("Unknown SNative function with ID %x", id)
}
return f, nil
}
// Get function by name
func (contract *SNativeContractDescription) FunctionByName(name string) (*SNativeFunctionDescription, error) {
for _, f := range contract.functions {
if f.Name == name {
return f, nil
}
}
return nil, fmt.Errorf("Unknown SNative function with name %s", name)
}
// Get functions in order of declaration
func (contract *SNativeContractDescription) Functions() []*SNativeFunctionDescription {
functions := make([]*SNativeFunctionDescription, len(contract.functions))
copy(functions, contract.functions)
return functions
}
//
// SNative functions
//
// Get function signature
func (function *SNativeFunctionDescription) Signature() string {
argTypeNames := make([]string, len(function.Args))
for i, arg := range function.Args {
argTypeNames[i] = string(arg.TypeName)
}
return fmt.Sprintf("%s(%s)", function.Name,
strings.Join(argTypeNames, ","))
}
// Get function calling identifier FunctionSelector
func (function *SNativeFunctionDescription) ID() abi.FunctionSelector {
return firstFourBytes(sha3.Sha3([]byte(function.Signature())))
}
// Get number of function arguments
func (function *SNativeFunctionDescription) NArgs() int {
return len(function.Args)
}
func abiArg(name string, abiTypeName abi.TypeName) abi.Arg {
return abi.Arg{
Name: name,
TypeName: abiTypeName,
}
}
func abiReturn(name string, abiTypeName abi.TypeName) abi.Return {
return abi.Return{
Name: name,
TypeName: abiTypeName,
}
}
// Permission function defintions
// TODO: catch errors, log em, return 0s to the vm (should some errors cause exceptions though?)
func hasBase(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, permNum := returnTwoArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
permN := ptypes.PermFlag(Uint64FromWord256(permNum)) // already shifted
if !ValidPermN(permN) {
return nil, ptypes.ErrInvalidPermission(permN)
}
permInt := byteFromBool(HasPermission(appState, vmAcc, permN))
dbg.Printf("snative.hasBasePerm(0x%X, %b) = %v\n", addr.Postfix(20), permN, permInt)
return LeftPadWord256([]byte{permInt}).Bytes(), nil
}
func setBase(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, permNum, permVal := returnThreeArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
permN := ptypes.PermFlag(Uint64FromWord256(permNum))
if !ValidPermN(permN) {
return nil, ptypes.ErrInvalidPermission(permN)
}
permV := !permVal.IsZero()
if err = vmAcc.Permissions.Base.Set(permN, permV); err != nil {
return nil, err
}
appState.UpdateAccount(vmAcc)
dbg.Printf("snative.setBasePerm(0x%X, %b, %v)\n", addr.Postfix(20), permN, permV)
return effectivePermBytes(vmAcc.Permissions.Base, globalPerms(appState)), nil
}
func unsetBase(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, permNum := returnTwoArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
permN := ptypes.PermFlag(Uint64FromWord256(permNum))
if !ValidPermN(permN) {
return nil, ptypes.ErrInvalidPermission(permN)
}
if err = vmAcc.Permissions.Base.Unset(permN); err != nil {
return nil, err
}
appState.UpdateAccount(vmAcc)
dbg.Printf("snative.unsetBasePerm(0x%X, %b)\n", addr.Postfix(20), permN)
return effectivePermBytes(vmAcc.Permissions.Base, globalPerms(appState)), nil
}
func setGlobal(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
permNum, permVal := returnTwoArgs(args)
vmAcc := appState.GetAccount(ptypes.GlobalPermissionsAddress256)
if vmAcc == nil {
sanity.PanicSanity("cant find the global permissions account")
}
permN := ptypes.PermFlag(Uint64FromWord256(permNum))
if !ValidPermN(permN) {
return nil, ptypes.ErrInvalidPermission(permN)
}
permV := !permVal.IsZero()
if err = vmAcc.Permissions.Base.Set(permN, permV); err != nil {
return nil, err
}
appState.UpdateAccount(vmAcc)
dbg.Printf("snative.setGlobalPerm(%b, %v)\n", permN, permV)
return permBytes(vmAcc.Permissions.Base.ResultantPerms()), nil
}
func hasRole(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, role := returnTwoArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
roleS := string(role.Bytes())
permInt := byteFromBool(vmAcc.Permissions.HasRole(roleS))
dbg.Printf("snative.hasRole(0x%X, %s) = %v\n", addr.Postfix(20), roleS, permInt > 0)
return LeftPadWord256([]byte{permInt}).Bytes(), nil
}
func addRole(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, role := returnTwoArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
roleS := string(role.Bytes())
permInt := byteFromBool(vmAcc.Permissions.AddRole(roleS))
appState.UpdateAccount(vmAcc)
dbg.Printf("snative.addRole(0x%X, %s) = %v\n", addr.Postfix(20), roleS, permInt > 0)
return LeftPadWord256([]byte{permInt}).Bytes(), nil
}
func removeRole(appState AppState, caller *Account, args []byte, gas *int64) (output []byte, err error) {
addr, role := returnTwoArgs(args)
vmAcc := appState.GetAccount(addr)
if vmAcc == nil {
return nil, fmt.Errorf("Unknown account %X", addr)
}
roleS := string(role.Bytes())
permInt := byteFromBool(vmAcc.Permissions.RmRole(roleS))
appState.UpdateAccount(vmAcc)
dbg.Printf("snative.rmRole(0x%X, %s) = %v\n", addr.Postfix(20), roleS, permInt > 0)
return LeftPadWord256([]byte{permInt}).Bytes(), nil
}
//------------------------------------------------------------------------------------------------
// Errors and utility funcs
type ErrInvalidPermission struct {
Address Word256
SNative string
}
func (e ErrInvalidPermission) Error() string {
return fmt.Sprintf("Account %X does not have permission snative.%s", e.Address.Postfix(20), e.SNative)
}
// Checks if a permission flag is valid (a known base chain or snative permission)
func ValidPermN(n ptypes.PermFlag) bool {
return n <= ptypes.TopPermFlag
}
// Get the global BasePermissions
func globalPerms(appState AppState) ptypes.BasePermissions {
vmAcc := appState.GetAccount(ptypes.GlobalPermissionsAddress256)
if vmAcc == nil {
sanity.PanicSanity("cant find the global permissions account")
}
return vmAcc.Permissions.Base
}
// Compute the effective permissions from an Account's BasePermissions by
// taking the bitwise or with the global BasePermissions resultant permissions
func effectivePermBytes(basePerms ptypes.BasePermissions,
globalPerms ptypes.BasePermissions) []byte {
return permBytes(basePerms.ResultantPerms() | globalPerms.ResultantPerms())
}
func permBytes(basePerms ptypes.PermFlag) []byte {
return Uint64ToWord256(uint64(basePerms)).Bytes()
}
// CONTRACT: length has already been checked
func returnTwoArgs(args []byte) (a Word256, b Word256) {
copy(a[:], args[:32])
copy(b[:], args[32:64])
return
}
// CONTRACT: length has already been checked
func returnThreeArgs(args []byte) (a Word256, b Word256, c Word256) {
copy(a[:], args[:32])
copy(b[:], args[32:64])
copy(c[:], args[64:96])
return
}
func byteFromBool(b bool) byte {
if b {
return 0x1
}
return 0x0
}
func firstFourBytes(byteSlice []byte) [4]byte {
var bs [4]byte
copy(bs[:], byteSlice[:4])
return bs
}