From 4de0ec6a3bb7b8a9f8bf5cc936f5baeecb202f0d Mon Sep 17 00:00:00 2001
From: Adphi <philippe.adrien.nousse@gmail.com>
Date: Sat, 16 Jul 2022 16:43:00 +0200
Subject: [PATCH] add metadata forwarder server interceptors

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>
---
 interceptors/auth/token.go       |  2 +-
 interceptors/metadata/forward.go | 53 ++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 interceptors/metadata/forward.go

diff --git a/interceptors/auth/token.go b/interceptors/auth/token.go
index 6c8caf9..485dcfa 100644
--- a/interceptors/auth/token.go
+++ b/interceptors/auth/token.go
@@ -22,5 +22,5 @@ func makeTokenAuthFunc(v TokenValidator) grpc_auth.AuthFunc {
 }
 
 func NewBearerClientInterceptors(token string) interceptors.ClientInterceptors {
-	return metadata.NewInterceptors("authorization", "Bearer "+token)
+	return metadata.NewInterceptors("authorization", "bearer "+token)
 }
diff --git a/interceptors/metadata/forward.go b/interceptors/metadata/forward.go
new file mode 100644
index 0000000..dd01c2b
--- /dev/null
+++ b/interceptors/metadata/forward.go
@@ -0,0 +1,53 @@
+package metadata
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+
+	"go.linka.cloud/grpc/interceptors"
+)
+
+func NewForwardInterceptors() interceptors.ServerInterceptors {
+	return &forward{}
+}
+
+type forward struct{}
+
+func (f *forward) UnaryServerInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
+		if md, ok := metadata.FromIncomingContext(ctx); ok {
+			ctx = metadata.NewOutgoingContext(ctx, md.Copy())
+		}
+		return handler(ctx, req)
+	}
+}
+
+func (f *forward) StreamServerInterceptor() grpc.StreamServerInterceptor {
+	return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		ctx := ss.Context()
+		md1, ok := metadata.FromIncomingContext(ctx)
+		if !ok {
+			return handler(srv, ss)
+		}
+		o := md1.Copy()
+		if md2, ok := metadata.FromOutgoingContext(ctx); ok {
+			o = metadata.Join(o, md2.Copy())
+		}
+		return handler(srv, NewContextServerStream(metadata.NewOutgoingContext(ctx, o), ss))
+	}
+}
+
+func NewContextServerStream(ctx context.Context, ss grpc.ServerStream) grpc.ServerStream {
+	return &ContextWrapper{ServerStream: ss, ctx: ctx}
+}
+
+type ContextWrapper struct {
+	grpc.ServerStream
+	ctx context.Context
+}
+
+func (w *ContextWrapper) Context() context.Context {
+	return w.ctx
+}