path: root/signer/rules/rules.go

// Copyright 2018 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package rules

import (
    "encoding/json"
    "fmt"
    "os"
    "strings"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/internal/ethapi"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/signer/core"
    "github.com/ethereum/go-ethereum/signer/rules/deps"
    "github.com/ethereum/go-ethereum/signer/storage"
    "github.com/robertkrimen/otto"
)

var (
    BigNumber_JS = deps.MustAsset("bignumber.js")
)

// consoleOutput is an override for the console.log and console.error methods to
// stream the output into the configured output stream instead of stdout.
func consoleOutput(call otto.FunctionCall) otto.Value {
    output := []string{"JS:> "}
    for _, argument := range call.ArgumentList {
        output = append(output, fmt.Sprintf("%v", argument))
    }
    fmt.Fprintln(os.Stdout, strings.Join(output, " "))
    return otto.Value{}
}

// rulesetUI provides an implementation of SignerUI that evaluates a javascript
// file for each defined UI-method
type rulesetUI struct {
    next        core.SignerUI // The next handler, for manual processing
    storage     storage.Storage
    credentials storage.Storage
    jsRules     string // The rules to use
}

func NewRuleEvaluator(next core.SignerUI, jsbackend, credentialsBackend storage.Storage) (*rulesetUI, error) {
    c := &rulesetUI{
        next:        next,
        storage:     jsbackend,
        credentials: credentialsBackend,
        jsRules:     "",
    }

    return c, nil
}

func (r *rulesetUI) Init(javascriptRules string) error {
    r.jsRules = javascriptRules
    return nil
}
func (r *rulesetUI) execute(jsfunc string, jsarg interface{}) (otto.Value, error) {

    // Instantiate a fresh vm engine every time
    vm := otto.New()
    // Set the native callbacks
    consoleObj, _ := vm.Get("console")
    consoleObj.Object().Set("log", consoleOutput)
    consoleObj.Object().Set("error", consoleOutput)
    vm.Set("storage", r.storage)

    // Load bootstrap libraries
    script, err := vm.Compile("bignumber.js", BigNumber_JS)
    if err != nil {
        log.Warn("Failed loading libraries", "err", err)
        return otto.UndefinedValue(), err
    }
    vm.Run(script)

    // Run the actual rule implementation
    _, err = vm.Run(r.jsRules)
    if err != nil {
        log.Warn("Execution failed", "err", err)
        return otto.UndefinedValue(), err
    }

    // And the actual call
    // All calls are objects with the parameters being keys in that object.
    // To provide additional insulation between js and go, we serialize it into JSON on the Go-side,
    // and deserialize it on the JS side.

    jsonbytes, err := json.Marshal(jsarg)
    if err != nil {
        log.Warn("failed marshalling data", "data", jsarg)
        return otto.UndefinedValue(), err
    }
    // Now, we call foobar(JSON.parse(<jsondata>)).
    var call string
    if len(jsonbytes) > 0 {
        call = fmt.Sprintf("%v(JSON.parse(%v))", jsfunc, string(jsonbytes))
    } else {
        call = fmt.Sprintf("%v()", jsfunc)
    }
    return vm.Run(call)
}

func (r *rulesetUI) checkApproval(jsfunc string, jsarg []byte, err error) (bool, error) {
    if err != nil {
        return false, err
    }
    v, err := r.execute(jsfunc, string(jsarg))
    if err != nil {
        log.Info("error occurred during execution", "error", err)
        return false, err
    }
    result, err := v.ToString()
    if err != nil {
        log.Info("error occurred during response unmarshalling", "error", err)
        return false, err
    }
    if result == "Approve" {
        log.Info("Op approved")
        return true, nil
    } else if result == "Reject" {
        log.Info("Op rejected")
        return false, nil
    }
    return false, fmt.Errorf("Unknown response")
}

func (r *rulesetUI) ApproveTx(request *core.SignTxRequest) (core.SignTxResponse, error) {
    jsonreq, err := json.Marshal(request)
    approved, err := r.checkApproval("ApproveTx", jsonreq, err)
    if err != nil {
        log.Info("Rule-based approval error, going to manual", "error", err)
        return r.next.ApproveTx(request)
    }

    if approved {
        return core.SignTxResponse{
                Transaction: request.Transaction,
                Approved:    true,
                Password:    r.lookupPassword(request.Transaction.From.Address()),
            },
            nil
    }
    return core.SignTxResponse{Approved: false}, err
}

func (r *rulesetUI) lookupPassword(address common.Address) string {
    return r.credentials.Get(strings.ToLower(address.String()))
}

func (r *rulesetUI) ApproveSignData(request *core.SignDataRequest) (core.SignDataResponse, error) {
    jsonreq, err := json.Marshal(request)
    approved, err := r.checkApproval("ApproveSignData", jsonreq, err)
    if err != nil {
        log.Info("Rule-based approval error, going to manual", "error", err)
        return r.next.ApproveSignData(request)
    }
    if approved {
        return core.SignDataResponse{Approved: true, Password: r.lookupPassword(request.Address.Address())}, nil
    }
    return core.SignDataResponse{Approved: false, Password: ""}, err
}

func (r *rulesetUI) ApproveExport(request *core.ExportRequest) (core.ExportResponse, error) {
    jsonreq, err := json.Marshal(request)
    approved, err := r.checkApproval("ApproveExport", jsonreq, err)
    if err != nil {
        log.Info("Rule-based approval error, going to manual", "error", err)
        return r.next.ApproveExport(request)
    }
    if approved {
        return core.ExportResponse{Approved: true}, nil
    }
    return core.ExportResponse{Approved: false}, err
}

func (r *rulesetUI) ApproveImport(request *core.ImportRequest) (core.ImportResponse, error) {
    // This cannot be handled by rules, requires setting a password
    // dispatch to next
    return r.next.ApproveImport(request)
}

func (r *rulesetUI) ApproveListing(request *core.ListRequest) (core.ListResponse, error) {
    jsonreq, err := json.Marshal(request)
    approved, err := r.checkApproval("ApproveListing", jsonreq, err)
    if err != nil {
        log.Info("Rule-based approval error, going to manual", "error", err)
        return r.next.ApproveListing(request)
    }
    if approved {
        return core.ListResponse{Accounts: request.Accounts}, nil
    }
    return core.ListResponse{}, err
}

func (r *rulesetUI) ApproveNewAccount(request *core.NewAccountRequest) (core.NewAccountResponse, error) {
    // This cannot be handled by rules, requires setting a password
    // dispatch to next
    return r.next.ApproveNewAccount(request)
}

func (r *rulesetUI) ShowError(message string) {
    log.Error(message)
    r.next.ShowError(message)
}

func (r *rulesetUI) ShowInfo(message string) {
    log.Info(message)
    r.next.ShowInfo(message)
}
func (r *rulesetUI) OnSignerStartup(info core.StartupInfo) {
    jsonInfo, err := json.Marshal(info)
    if err != nil {
        log.Warn("failed marshalling data", "data", info)
        return
    }
    r.next.OnSignerStartup(info)
    _, err = r.execute("OnSignerStartup", string(jsonInfo))
    if err != nil {
        log.Info("error occurred during execution", "error", err)
    }
}

func (r *rulesetUI) OnApprovedTx(tx ethapi.SignTransactionResult) {
    jsonTx, err := json.Marshal(tx)
    if err != nil {
        log.Warn("failed marshalling transaction", "tx", tx)
        return
    }
    _, err = r.execute("OnApprovedTx", string(jsonTx))
    if err != nil {
        log.Info("error occurred during execution", "error", err)
    }
}