From d77770d96ea72a04ca4621e0516938648a3bac0d Mon Sep 17 00:00:00 2001
From: Marius van der Wijden <m.vanderwijden@live.de>
Date: Tue, 26 May 2020 13:02:33 +0200
Subject: [PATCH] rpc: internal/ethapi: added custom error types

---
 console/bridge.go      |  2 ++
 internal/ethapi/api.go | 28 ++++++++++++++++++++++++++--
 rpc/json.go            |  4 ++++
 rpc/types.go           |  6 ++++++
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/console/bridge.go b/console/bridge.go
index ace8aeeba0..436db6ca5b 100644
--- a/console/bridge.go
+++ b/console/bridge.go
@@ -435,6 +435,8 @@ func (b *bridge) Send(call jsre.Call) (goja.Value, error) {
 			}
 		case rpc.Error:
 			setError(resp, err.ErrorCode(), err.Error())
+		case rpc.DataError:
+			resp.Set("error", map[string]interface{}{"code": -32603, "message": err.Error(), "data": err.ErrorData()})
 		default:
 			setError(resp, -32603, err.Error())
 		}
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 0a25cdc70c..28aec5228c 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -864,6 +864,21 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 	return result, err
 }
 
+var _ rpc.DataError = (*revertError)(nil)
+
+type revertError struct {
+	err     string      // The error string
+	errData interface{} // additional data
+}
+
+func (e revertError) Error() string {
+	return e.err
+}
+
+func (e revertError) ErrorData() interface{} {
+	return e.errData
+}
+
 // Call executes the given transaction on the state for the given block number.
 //
 // Additionally, the caller can specify a batch of contract for fields overriding.
@@ -883,12 +898,17 @@ func (s *PublicBlockChainAPI) Call(ctx context.Context, args CallArgs, blockNrOr
 	if len(result.Revert()) > 0 {
 		reason, err := abi.UnpackRevert(result.Revert())
 		if err == nil {
-			return nil, fmt.Errorf("execution reverted: %v", reason)
+			return nil, &revertError{
+				err:     "execution reverted",
+				errData: reason,
+			}
 		}
 	}
-	return result.Return(), nil
+	return result.Return(), result.Err
 }
 
+var _ rpc.DataError = (*estimateGasError)(nil)
+
 type estimateGasError struct {
 	error  string // Concrete error type if it's failed to estimate gas usage
 	vmerr  error  // Additional field, it's non-nil if the given transaction is invalid
@@ -906,6 +926,10 @@ func (e estimateGasError) Error() string {
 	return errMsg
 }
 
+func (e estimateGasError) ErrorData() interface{} {
+	return e.revert
+}
+
 func DoEstimateGas(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.BlockNumberOrHash, gasCap *big.Int) (hexutil.Uint64, error) {
 	// Binary search the gas requirement, as it may be higher than the amount used
 	var (
diff --git a/rpc/json.go b/rpc/json.go
index 61631a3d76..5b48e01e67 100644
--- a/rpc/json.go
+++ b/rpc/json.go
@@ -115,6 +115,10 @@ func errorMessage(err error) *jsonrpcMessage {
 	if ok {
 		msg.Error.Code = ec.ErrorCode()
 	}
+	de, ok := err.(DataError)
+	if ok {
+		msg.Error.Data = de.ErrorData()
+	}
 	return msg
 }
 
diff --git a/rpc/types.go b/rpc/types.go
index dc9248d0fe..bab1b3957b 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -41,6 +41,12 @@ type Error interface {
 	ErrorCode() int // returns the code
 }
 
+// A DataError contains some data in addition to the error message.
+type DataError interface {
+	Error() string          // returns the message
+	ErrorData() interface{} // returns the error data
+}
+
 // ServerCodec implements reading, parsing and writing RPC messages for the server side of
 // a RPC session. Implementations must be go-routine safe since the codec can be called in
 // multiple go-routines concurrently.