[systemd-devel] [PATCH 1/2] Ignore IPv6 link-local addresses

[Eelco Dolstra]

Returning IPv6 link-local addresses is a bad idea, because they only
work if an application connects specifically over the corresponding
interface.  So you get errors like:

  $ curl -6 http://my-machine/
  curl: (7) Failed to connect to fe80::d6be:d9ff:fe1b:8477: Invalid argument

To prevent this, this patch filters out link-local addresses.  So if
you don't have a routable IPv6 address, nss-myhostname will fall back
to returning ::1.
---
 src/nss-myhostname/netlink.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/nss-myhostname/netlink.c b/src/nss-myhostname/netlink.c
index 53c3b50..621ca1d 100644
--- a/src/nss-myhostname/netlink.c
+++ b/src/nss-myhostname/netlink.c
@@ -155,6 +155,10 @@ int ifconf_acquire_addresses(struct address **_list, unsigned *_n_list) {
                             ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE)
                                 continue;
 
+                        if (ifaddrmsg->ifa_family == AF_INET6 &&
+                            ifaddrmsg->ifa_scope == RT_SCOPE_LINK)
+                                continue;
+
                         if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED)
                                 continue;
 
-- 
1.8.1