From: David Schweizer <dschweizer@opensourcerouting.org>
Date: Wed, 12 Feb 2025 12:07:38 +0000 (+0100)
Subject: lib,zebra: Allow class E prefixes in RIB
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=1eef3a77e32b711311551a699b475317f8f9729a;p=mirror%2Ffrr.git

lib,zebra: Allow class E prefixes in RIB

Changes allow ipv4 class E addresses and prefixes in the 240.0.0.0/4
range to be configured on interfaces, imported from the kernel routing
table and redistributed as connected routes in zebra by default.

Changes also fix routes with class E prefixes in kernel routing table
getting rejected by zebra during early daemon startup.

Drivin this change in default behavior are cloud providers (with
customers still using obsolete ipv4 protocol, i.e. Azure, AWS) running
out of ip space and abusing class E for addressing instances (announced
via BGP) over tunneling connections back to customers on premise
infrastructure.

Signed-off-by: David Schweizer <dschweizer@opensourcerouting.org>
---

diff --git a/lib/prefix.c b/lib/prefix.c
index 2485c3e61b..feaf3e5f1c 100644
--- a/lib/prefix.c
+++ b/lib/prefix.c
@@ -1439,10 +1439,13 @@ bool ipv4_unicast_valid(const struct in_addr *addr)
 {
 	in_addr_t ip = ntohl(addr->s_addr);
 
+	if (IPV4_CLASS_E(ip))
+		return true;
+
 	if (IPV4_CLASS_D(ip))
 		return false;
 
-	if (IPV4_NET0(ip) || IPV4_NET127(ip) || IPV4_CLASS_E(ip)) {
+	if (IPV4_NET0(ip) || IPV4_NET127(ip)) {
 		if (cmd_allow_reserved_ranges_get())
 			return true;
 		else
diff --git a/zebra/zebra_rib.c b/zebra/zebra_rib.c
index a1c8cd3059..8cea605f41 100644
--- a/zebra/zebra_rib.c
+++ b/zebra/zebra_rib.c
@@ -391,11 +391,10 @@ int zebra_check_addr(const struct prefix *p)
 	if (p->family == AF_INET) {
 		uint32_t addr;
 
-		addr = p->u.prefix4.s_addr;
-		addr = ntohl(addr);
+		addr = ntohl(p->u.prefix4.s_addr);
 
-		if (IPV4_NET127(addr) || IN_CLASSD(addr)
-		    || IPV4_LINKLOCAL(addr))
+		if (IPV4_NET127(addr) || IN_CLASSD(addr) ||
+		    (IPV4_LINKLOCAL(addr) && !IPV4_CLASS_E(addr)))
 			return 0;
 	}
 	if (p->family == AF_INET6) {