Teach VCC to do modules on INT, this is handy in vcl_synth{}:

    sub vcl_synth {
        if (resp.status == 12404) {
            [...]       // this specific 404
        } else if (resp.status % 1000 == 404) {
            [...]       // all other 404's
        }
    }

bin/varnishtest/tests/v00020.vtc

@@ -56,6 +56,13 @@ varnish v1 -errvcl {BOOL + BOOL not possible.} {
 	}
 }
 
+varnish v1 -errvcl {Operator % only possible on INT} {
+	sub vcl_recv {
+		if (req.ttl % 1000) {
+		}
+	}
+}
+
 varnish v1 -vcl {
 	backend b { .host = "${localhost}"; }
 	sub vcl_recv {

bin/varnishtest/tests/v00050.vtc

@@ -123,6 +123,7 @@ varnish v1 -vcl+backend {
 	    }
 	    set resp.status = 22302;
 	    set resp.reason = "Wrong Postcode";
+	    set resp.http.residual = resp.status % 10000;
 	    return (deliver);
 	}
 } -start
@@ -159,6 +160,7 @@ client c1 {
 	txreq -url "/synth"
 	rxresp
 	expect resp.status == 302
+	expect resp.http.residual == 2302
 	expect resp.reason == "Wrong Postcode"
 } -run
 

lib/libvcc/vcc_expr.c

@@ -911,13 +911,20 @@ vcc_expr_mul(struct vcc *tl, struct expr **e, vcc_type_t fmt)
 	struct expr *e2;
 	vcc_type_t f2;
 	struct token *tk;
+	char buf[24];
 
 	*e = NULL;
 	vcc_expr4(tl, e, fmt);
 	ERRCHK(tl);
 	AN(*e);
 
-	while (tl->t->tok == '*' || tl->t->tok == '/') {
+	while (tl->t->tok == '*' || tl->t->tok == '/' || tl->t->tok == '%') {
+		if (tl->t->tok == '%' && ((*e)->fmt != INT)) {
+			VSB_printf(tl->sb,
+			    "Operator %% only possible on INT.\n");
+			vcc_ErrWhere(tl, tl->t);
+			return;
+		}
 		f2 = (*e)->fmt->multype;
 		if (f2 == NULL) {
 			VSB_printf(tl->sb,
@@ -936,10 +943,8 @@ vcc_expr_mul(struct vcc *tl, struct expr **e, vcc_type_t fmt)
 			vcc_ErrWhere(tl, tk);
 			return;
 		}
-		if (tk->tok == '*')
-			*e = vcc_expr_edit(tl, (*e)->fmt, "(\v1*\v2)", *e, e2);
-		else
-			*e = vcc_expr_edit(tl, (*e)->fmt, "(\v1/\v2)", *e, e2);
+		bprintf(buf, "(\v1%c\v2)", tk->tok);
+		*e = vcc_expr_edit(tl, (*e)->fmt, buf, *e, e2);
 	}
 }