A /31-addressed interface requires a 255.255.255.255 broadcast, because
there is no room for a proper broadcast address. Without this, any packet
destinated to the other end of the link is sent as broadcast, which is
incorrect.
Signed-off-by: Baptiste Jonglez <g...@bitsofnetworks.org>
---
interface-ip.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/interface-ip.c b/interface-ip.c
index 8eb2ff3..439b8af 100644
--- a/interface-ip.c
+++ b/interface-ip.c
@@ -473,11 +473,16 @@ interface_update_proto_addr(struct vlist_tree *tree,
if ((a_new->flags & DEVADDR_FAMILY) == DEVADDR_INET4 &&
!a_new->broadcast) {
- uint32_t mask = ~0;
- uint32_t *a = (uint32_t *) &a_new->addr;
-
- mask >>= a_new->mask;
- a_new->broadcast = *a | htonl(mask);
+ /* /31 addressing needs 255.255.255.255 broadcast */
+ if (a_new->mask == 31) {
+ a_new->broadcast = (uint32_t) ~0;
+ } else {
+ uint32_t mask = ~0;
+ uint32_t *a = (uint32_t *) &a_new->addr;
+
+ mask >>= a_new->mask;
+ a_new->broadcast = *a | htonl(mask);
+ }
}
}
--
2.5.1
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