1 files changed, 163 insertions, 0 deletions
diff --git a/signer/core/validation.go b/signer/core/validation.go
new file mode 100644
index 000000000..97bb3b685
--- /dev/null
+++ b/signer/core/validation.go
@@ -0,0 +1,163 @@
+// 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 core
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// The validation package contains validation checks for transactions
+// - ABI-data validation
+// - Transaction semantics validation
+// The package provides warnings for typical pitfalls
+
+func (vs *ValidationMessages) crit(msg string) {
+	vs.Messages = append(vs.Messages, ValidationInfo{"CRITICAL", msg})
+}
+func (vs *ValidationMessages) warn(msg string) {
+	vs.Messages = append(vs.Messages, ValidationInfo{"WARNING", msg})
+}
+func (vs *ValidationMessages) info(msg string) {
+	vs.Messages = append(vs.Messages, ValidationInfo{"Info", msg})
+}
+
+type Validator struct {
+	db *AbiDb
+}
+
+func NewValidator(db *AbiDb) *Validator {
+	return &Validator{db}
+}
+func testSelector(selector string, data []byte) (*decodedCallData, error) {
+	if selector == "" {
+		return nil, fmt.Errorf("selector not found")
+	}
+	abiData, err := MethodSelectorToAbi(selector)
+	if err != nil {
+		return nil, err
+	}
+	info, err := parseCallData(data, string(abiData))
+	if err != nil {
+		return nil, err
+	}
+	return info, nil
+
+}
+
+// validateCallData checks if the ABI-data + methodselector (if given) can be parsed and seems to match
+func (v *Validator) validateCallData(msgs *ValidationMessages, data []byte, methodSelector *string) {
+	if len(data) == 0 {
+		return
+	}
+	if len(data) < 4 {
+		msgs.warn("Tx contains data which is not valid ABI")
+		return
+	}
+	var (
+		info *decodedCallData
+		err  error
+	)
+	// Check the provided one
+	if methodSelector != nil {
+		info, err = testSelector(*methodSelector, data)
+		if err != nil {
+			msgs.warn(fmt.Sprintf("Tx contains data, but provided ABI signature could not be matched: %v", err))
+		} else {
+			msgs.info(info.String())
+			//Successfull match. add to db if not there already (ignore errors there)
+			v.db.AddSignature(*methodSelector, data[:4])
+		}
+		return
+	}
+	// Check the db
+	selector, err := v.db.LookupMethodSelector(data[:4])
+	if err != nil {
+		msgs.warn(fmt.Sprintf("Tx contains data, but the ABI signature could not be found: %v", err))
+		return
+	}
+	info, err = testSelector(selector, data)
+	if err != nil {
+		msgs.warn(fmt.Sprintf("Tx contains data, but provided ABI signature could not be matched: %v", err))
+	} else {
+		msgs.info(info.String())
+	}
+}
+
+// validateSemantics checks if the transactions 'makes sense', and generate warnings for a couple of typical scenarios
+func (v *Validator) validate(msgs *ValidationMessages, txargs *SendTxArgs, methodSelector *string) error {
+	// Prevent accidental erroneous usage of both 'input' and 'data'
+	if txargs.Data != nil && txargs.Input != nil && !bytes.Equal(*txargs.Data, *txargs.Input) {
+		// This is a showstopper
+		return errors.New(`Ambiguous request: both "data" and "input" are set and are not identical`)
+	}
+	var (
+		data []byte
+	)
+	// Place data on 'data', and nil 'input'
+	if txargs.Input != nil {
+		txargs.Data = txargs.Input
+		txargs.Input = nil
+	}
+	if txargs.Data != nil {
+		data = *txargs.Data
+	}
+
+	if txargs.To == nil {
+		//Contract creation should contain sufficient data to deploy a contract
+		// A typical error is omitting sender due to some quirk in the javascript call
+		// e.g. https://github.com/ethereum/go-ethereum/issues/16106
+		if len(data) == 0 {
+			if txargs.Value.ToInt().Cmp(big.NewInt(0)) > 0 {
+				// Sending ether into black hole
+				return errors.New(`Tx will create contract with value but empty code!`)
+			}
+			// No value submitted at least
+			msgs.crit("Tx will create contract with empty code!")
+		} else if len(data) < 40 { //Arbitrary limit
+			msgs.warn(fmt.Sprintf("Tx will will create contract, but payload is suspiciously small (%d b)", len(data)))
+		}
+		// methodSelector should be nil for contract creation
+		if methodSelector != nil {
+			msgs.warn("Tx will create contract, but method selector supplied; indicating intent to call a method.")
+		}
+
+	} else {
+		if !txargs.To.ValidChecksum() {
+			msgs.warn("Invalid checksum on to-address")
+		}
+		// Normal transaction
+		if bytes.Equal(txargs.To.Address().Bytes(), common.Address{}.Bytes()) {
+			// Sending to 0
+			msgs.crit("Tx destination is the zero address!")
+		}
+		// Validate calldata
+		v.validateCallData(msgs, data, methodSelector)
+	}
+	return nil
+}
+
+// ValidateTransaction does a number of checks on the supplied transaction, and returns either a list of warnings,
+// or an error, indicating that the transaction should be immediately rejected
+func (v *Validator) ValidateTransaction(txArgs *SendTxArgs, methodSelector *string) (*ValidationMessages, error) {
+	msgs := &ValidationMessages{}
+	return msgs, v.validate(msgs, txArgs, methodSelector)
+}