rpcperms: add unique request ID

This commit adds a unique request ID that is the same for each gRPC
request and response intercept message or each request/response message
of a gRPC stream.

rpcperms/interceptor.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"sync"
+	"sync/atomic"
 
 	"github.com/btcsuite/btclog"
 	grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
@@ -134,6 +135,12 @@ var (
 //        | edited gRPC request to client
 //        v
 type InterceptorChain struct {
+	// lastRequestID is the ID of the last gRPC request or stream that was
+	// intercepted by the middleware interceptor.
+	//
+	// NOTE: Must be used atomically!
+	lastRequestID uint64
+
 	// Required by the grpc-gateway/v2 library for forward compatibility.
 	lnrpc.UnimplementedStateServer
 
@@ -790,7 +797,8 @@ func (r *InterceptorChain) middlewareUnaryServerInterceptor() grpc.UnaryServerIn
 			return nil, err
 		}
 
-		err = r.acceptRequest(msg)
+		requestID := atomic.AddUint64(&r.lastRequestID, 1)
+		err = r.acceptRequest(requestID, msg)
 		if err != nil {
 			return nil, err
 		}
@@ -800,7 +808,9 @@ func (r *InterceptorChain) middlewareUnaryServerInterceptor() grpc.UnaryServerIn
 			return resp, respErr
 		}
 
-		return r.interceptResponse(ctx, false, info.FullMethod, resp)
+		return r.interceptResponse(
+			ctx, requestID, false, info.FullMethod, resp,
+		)
 	}
 }
 
@@ -845,13 +855,15 @@ func (r *InterceptorChain) middlewareStreamServerInterceptor() grpc.StreamServer
 			return err
 		}
 
-		err = r.acceptRequest(msg)
+		requestID := atomic.AddUint64(&r.lastRequestID, 1)
+		err = r.acceptRequest(requestID, msg)
 		if err != nil {
 			return err
 		}
 
 		wrappedSS := &serverStreamWrapper{
 			ServerStream: ss,
+			requestID:    requestID,
 			fullMethod:   info.FullMethod,
 			interceptor:  r,
 		}
@@ -900,7 +912,9 @@ func (r *InterceptorChain) middlewareRegistered() bool {
 // registered for it. This means either a middleware has requested read-only
 // access or the request actually has a macaroon which a caveat the middleware
 // registered for.
-func (r *InterceptorChain) acceptRequest(msg *InterceptionRequest) error {
+func (r *InterceptorChain) acceptRequest(requestID uint64,
+	msg *InterceptionRequest) error {
+
 	r.RLock()
 	defer r.RUnlock()
 
@@ -915,7 +929,7 @@ func (r *InterceptorChain) acceptRequest(msg *InterceptionRequest) error {
 			continue
 		}
 
-		resp, err := middleware.intercept(msg)
+		resp, err := middleware.intercept(requestID, msg)
 
 		// Error during interception itself.
 		if err != nil {
@@ -936,7 +950,8 @@ func (r *InterceptorChain) acceptRequest(msg *InterceptionRequest) error {
 // overwrite/replace the response, this needs to be handled differently than the
 // request/auth path above.
 func (r *InterceptorChain) interceptResponse(ctx context.Context,
-	isStream bool, fullMethod string, m interface{}) (interface{}, error) {
+	requestID uint64, isStream bool, fullMethod string,
+	m interface{}) (interface{}, error) {
 
 	r.RLock()
 	defer r.RUnlock()
@@ -960,7 +975,7 @@ func (r *InterceptorChain) interceptResponse(ctx context.Context,
 			continue
 		}
 
-		resp, err := middleware.intercept(msg)
+		resp, err := middleware.intercept(requestID, msg)
 
 		// Error during interception itself.
 		if err != nil {
@@ -988,6 +1003,8 @@ type serverStreamWrapper struct {
 	// ServerStream is the stream that's being wrapped.
 	grpc.ServerStream
 
+	requestID uint64
+
 	fullMethod string
 
 	interceptor *InterceptorChain
@@ -997,7 +1014,7 @@ type serverStreamWrapper struct {
 // intercept streaming RPC responses.
 func (w *serverStreamWrapper) SendMsg(m interface{}) error {
 	newMsg, err := w.interceptor.interceptResponse(
-		w.ServerStream.Context(), true, w.fullMethod, m,
+		w.ServerStream.Context(), w.requestID, true, w.fullMethod, m,
 	)
 	if err != nil {
 		return err
@@ -1022,5 +1039,5 @@ func (w *serverStreamWrapper) RecvMsg(m interface{}) error {
 		return err
 	}
 
-	return w.interceptor.acceptRequest(msg)
+	return w.interceptor.acceptRequest(w.requestID, msg)
 }