From 97cf240fe0bc7bec20b697d16b6733f65246a21b Mon Sep 17 00:00:00 2001
From: Austin Roberts <austin.roberts@openrelay.xyz>
Date: Fri, 25 Jun 2021 13:55:31 -0500
Subject: [PATCH] Add tracer hooks for debug_traceCall, etc.

---
 eth/tracers/api.go       | 30 ++++++++++++++++++------------
 plugins/plugin_loader.go | 35 ++++++++++++++++++++++++++++++++---
 2 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/eth/tracers/api.go b/eth/tracers/api.go
index 65bf84dc4..d02f35730 100644
--- a/eth/tracers/api.go
+++ b/eth/tracers/api.go
@@ -40,6 +40,7 @@ import (
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/plugins"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
 )
@@ -799,19 +800,24 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *txTrac
 				return nil, err
 			}
 		}
-		// Constuct the JavaScript tracer to execute with
-		if tracer, err = New(*config.Tracer, txContext); err != nil {
-			return nil, err
-		}
-		// Handle timeouts and RPC cancellations
-		deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
-		go func() {
-			<-deadlineCtx.Done()
-			if deadlineCtx.Err() == context.DeadlineExceeded {
-				tracer.(*Tracer).Stop(errors.New("execution timeout"))
+		// Get the tracer from the plugin loader
+		if tr, ok := plugins.GetTracer(*config.Tracer); ok {
+			tracer = tr(statedb)
+		} else {
+			// Constuct the JavaScript tracer to execute with
+			if tracer, err = New(*config.Tracer, txContext); err != nil {
+				return nil, err
 			}
-		}()
-		defer cancel()
+			// Handle timeouts and RPC cancellations
+			deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
+			go func() {
+				<-deadlineCtx.Done()
+				if deadlineCtx.Err() == context.DeadlineExceeded {
+					tracer.(*Tracer).Stop(errors.New("execution timeout"))
+				}
+				}()
+				defer cancel()
+		}
 
 	case config == nil:
 		tracer = vm.NewStructLogger(nil)
diff --git a/plugins/plugin_loader.go b/plugins/plugin_loader.go
index 35290575c..a843678b7 100644
--- a/plugins/plugin_loader.go
+++ b/plugins/plugin_loader.go
@@ -5,6 +5,8 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/core/state"
 	"gopkg.in/urfave/cli.v1"
 	"flag"
 	"io/ioutil"
@@ -19,7 +21,7 @@ type Subcommand func(*cli.Context, []string) error
 
 
 type PluginLoader struct{
-	TracerPlugins map[string]interface{} // TODO: Set interface
+	Tracers map[string]func(*state.StateDB)vm.Tracer
 	StateHooks []interface{} // TODO: Set interface
 	ChainEventHooks []interface{} // TODO: Set interface
 	RPCPlugins []APILoader
@@ -76,7 +78,7 @@ func NewPluginLoader(target string) (*PluginLoader, error) {
 		if err == nil {
 			subcommands, ok := sb.(map[string]func(*cli.Context, []string) error)
 			if !ok {
-				log.Warn("Could not cast plugin.Subocmmands to `map[string]func(*cli.Context, []string) error`", "file", fpath)
+				log.Warn("Could not cast plugin.Subcommands to `map[string]func(*cli.Context, []string) error`", "file", fpath)
 			} else {
 				for k, v := range subcommands {
 					if _, ok := pl.Subcommands[k]; ok {
@@ -86,6 +88,20 @@ func NewPluginLoader(target string) (*PluginLoader, error) {
 				}
 			}
 		}
+		tr, err := plug.Lookup("Tracers")
+		if err == nil {
+			tracers, ok := tr.(map[string]func(*state.StateDB)vm.Tracer)
+			if !ok {
+				log.Warn("Could not cast plugin.Tracers to `map[string]vm.Tracer`", "file", fpath)
+			} else {
+				for k, v := range tracers {
+					if _, ok := pl.Tracers[k]; ok {
+						log.Warn("Tracer redeclared", "file", fpath, "tracer", k)
+					}
+					pl.Tracers[k] = v
+				}
+			}
+		}
 	}
 	return pl, nil
 }
@@ -133,8 +149,21 @@ func (pl *PluginLoader) GetAPIs(stack *node.Node, backend Backend) []rpc.API {
 
 func GetAPIs(stack *node.Node, backend Backend) []rpc.API {
 	if defaultPluginLoader == nil {
-		log.Warn("Attempting GetAPIs ,but default PluginLoader has not been initialized")
+		log.Warn("Attempting GetAPIs, but default PluginLoader has not been initialized")
 		return []rpc.API{}
 	 }
 	return defaultPluginLoader.GetAPIs(stack, backend)
 }
+
+func (pl *PluginLoader) GetTracer(s string) (func(*state.StateDB)vm.Tracer, bool) {
+	tr, ok := pl.Tracers[s]
+	return tr, ok
+}
+
+func GetTracer(s string) (func(*state.StateDB)vm.Tracer, bool) {
+	if defaultPluginLoader == nil {
+		log.Warn("Attempting GetTracer, but default PluginLoader has not been initialized")
+		return nil, false
+	}
+	return defaultPluginLoader.GetTracer(s)
+}