Add a hint for an invalid IP prefix

bird> eval 200.210.220.0/16
Invalid IPv4 prefix 200.210.220.0/16, maybe you wanted 200.210.0.0/16

bird> eval 1000:2000::/8
Invalid IPv6 prefix 1000:2000::/8, maybe you wanted 1000::/8

diff --git a/conf/confbase.Y b/conf/confbase.Y
index 47ee07cec6ff75fa38c0a255caaee21bb65f4238..e7fd1677a68fcd72df76e9c043ef34fdf8af8ffb 100644 (file)
--- a/conf/confbase.Y
+++ b/conf/confbase.Y
@@ -187,17 +187,24 @@ pxlen4:
 net_ip4_: IP4 pxlen4
 {
   net_fill_ip4(&($$), $1, $2);
-  if (!net_validate_ip4((net_addr_ip4 *) &($$)))
-    cf_error("Invalid IPv4 prefix");
+
+  net_addr_ip4 *n = (void *) &($$);
+  if (!net_validate_ip4(n))
+    cf_error("Invalid IPv4 prefix %I4/%d, maybe you wanted %I4/%d",
+            n->prefix, n->pxlen, ip4_and(n->prefix, ip4_mkmask(n->pxlen)), n->pxlen);
 };
 
 net_ip6_: IP6 '/' NUM
 {
-  net_fill_ip6(&($$), $1, $3);
   if ($3 < 0 || $3 > IP6_MAX_PREFIX_LENGTH)
     cf_error("Invalid prefix length %d", $3);
-  if (!net_validate_ip6((net_addr_ip6 *) &($$)))
-    cf_error("Invalid IPv6 prefix");
+
+  net_fill_ip6(&($$), $1, $3);
+
+  net_addr_ip6 *n = (void *) &($$);
+  if (!net_validate_ip6(n))
+    cf_error("Invalid IPv6 prefix %I6/%d, maybe you wanted %I6/%d",
+            n->prefix, n->pxlen, ip6_and(n->prefix, ip6_mkmask(n->pxlen)), n->pxlen);
 };
 
 net_vpn4_: VPN_RD net_ip4_