proxyd: Pass through finalized and safe tags

proxyd/proxyd/rewriter.go

@@ -159,6 +159,13 @@ func rewriteTagMap(rctx RewriteContext, m map[string]interface{}, key string) (b
 }
 
 func rewriteTag(rctx RewriteContext, current string) (string, bool, error) {
+	// If a tag is the safe or finalized block number, don't rewrite it.
+	// We have a custom check here because the rpc.BlockNumberOrHash type
+	// doesn't support these custom tags yet.
+	if current == "safe" || current == "finalized" {
+		return current, false, nil
+	}
+
 	jv, err := json.Marshal(current)
 	if err != nil {
 		return "", false, err
@@ -177,5 +184,6 @@ func rewriteTag(rctx RewriteContext, current string) (string, bool, error) {
 			return "", false, ErrRewriteBlockOutOfRange
 		}
 	}
+
 	return current, false, nil
 }

proxyd/proxyd/rewriter_test.go

@@ -308,6 +308,38 @@ func TestRewriteRequest(t *testing.T) {
 				require.Equal(t, hexutil.Uint64(100).String(), p[0])
 			},
 		},
+		{
+			name: "eth_getBlockByNumber finalized",
+			args: args{
+				rctx: RewriteContext{latest: hexutil.Uint64(100)},
+				req:  &RPCReq{Method: "eth_getBlockByNumber", Params: mustMarshalJSON([]string{"finalized"})},
+				res:  nil,
+			},
+			expected: RewriteNone,
+			check: func(t *testing.T, args args) {
+				var p []string
+				err := json.Unmarshal(args.req.Params, &p)
+				require.Nil(t, err)
+				require.Equal(t, 1, len(p))
+				require.Equal(t, "finalized", p[0])
+			},
+		},
+		{
+			name: "eth_getBlockByNumber safe",
+			args: args{
+				rctx: RewriteContext{latest: hexutil.Uint64(100)},
+				req:  &RPCReq{Method: "eth_getBlockByNumber", Params: mustMarshalJSON([]string{"safe"})},
+				res:  nil,
+			},
+			expected: RewriteNone,
+			check: func(t *testing.T, args args) {
+				var p []string
+				err := json.Unmarshal(args.req.Params, &p)
+				require.Nil(t, err)
+				require.Equal(t, 1, len(p))
+				require.Equal(t, "safe", p[0])
+			},
+		},
 		{
 			name: "eth_getBlockByNumber within range",
 			args: args{