go-usertoken/grpc.go

package usertoken

import (
	"context"

	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"
)

// UnaryServerInterceptor requires a bearer on every RPC.
// Success stores the Caller and the raw JWT on the handler context, same as
// [Auth.Middleware]. Native clients send metadata key "authorization".
// The HTTP gateway's forwarded header is "grpcgateway-authorization".
func (a *Auth) UnaryServerInterceptor() grpc.UnaryServerInterceptor {
	return func(ctx context.Context, req any, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
		raw, ok := bearerFromMetadata(ctx)
		if !ok {
			return nil, status.Error(codes.Unauthenticated, "unauthorized")
		}
		caller, err := a.Verify(ctx, raw)
		if err != nil {
			return nil, status.Error(codes.Unauthenticated, "unauthorized")
		}
		return handler(withAuth(ctx, caller, raw), req)
	}
}

func bearerFromMetadata(ctx context.Context) (string, bool) {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return "", false
	}
	for _, key := range []string{"authorization", "grpcgateway-authorization"} {
		vals := md.Get(key)
		if len(vals) == 0 {
			continue
		}
		if raw, ok := bearerToken(vals[0]); ok {
			return raw, true
		}
	}
	return "", false
}