From: Rafał Miłecki <ra...@milecki.pl>
1) We SHOULD do this according to the RFC 6762 (Section 11, "Source
Address Check").
2) We already do it for IPv6 unicast and both multicast interfaces
3) When receiving IPv4 packet we ignore it if TTL doesn't equal 255
In other words this fixes unicast communication between 2 umdns
instances.
Signed-off-by: Rafał Miłecki <ra...@milecki.pl>
---
interface.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/interface.c b/interface.c
index 587b188..76820c7 100644
--- a/interface.c
+++ b/interface.c
@@ -389,6 +389,7 @@ static void
reconnect_socket4(struct uloop_timeout *timeout)
{
struct interface *iface = container_of(timeout, struct interface,
reconnect);
+ int ttl = 255;
int yes = 1;
iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK |
USOCK_IPV4ONLY,
@@ -404,6 +405,9 @@ reconnect_socket4(struct uloop_timeout *timeout)
if (setsockopt(iface->fd.fd, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof(yes)) < 0)
fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
+ if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) < 0)
+ fprintf(stderr, "ioctl failed: IP_TTL\n");
+
if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes))
< 0)
fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
--
2.11.0
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