add auth interceptors

interceptors/auth/basic.go

@@ -0,0 +1,36 @@
+package auth
+
+import (
+	"context"
+	"encoding/base64"
+	"strings"
+
+	grpc_auth "github.com/grpc-ecosystem/go-grpc-middleware/auth"
+
+	"go.linka.cloud/grpc/errors"
+)
+
+func BasicAuth(user, password string) string {
+	return "basic " + base64.StdEncoding.EncodeToString([]byte(user+":"+password))
+}
+
+type BasicValidator func(ctx context.Context, user, password string) (context.Context,error)
+
+func makeBasicAuthFunc(v BasicValidator) grpc_auth.AuthFunc {
+	return func(ctx context.Context) (context.Context, error) {
+		a, err := grpc_auth.AuthFromMD(ctx, "basic")
+		if err != nil {
+			return ctx, err
+		}
+		c, err := base64.StdEncoding.DecodeString(a)
+		if err != nil {
+			return ctx, err
+		}
+		cs := string(c)
+		s := strings.IndexByte(cs, ':')
+		if s < 0 {
+			return ctx, errors.Unauthenticatedf("malformed basic auth")
+		}
+		return v(ctx, cs[:s], cs[s+1:])
+	}
+}