mdns: improve numerous aspects of Posix backend

Apple's default implementation of the Posix backend for mDNSResponder
has a number of weaknesses. Address several of them, most notably:

* Improve interface tracking, preventing confusion to mdns's state
  machine. Prevents spurious removal/republication cycles whenever
  network interfaces are added or removed.

* Support network interfaces whose indeces are great than 31. Indices
  grow past that range surprisingly quickly, especially with multi-
  homed, mobile, wifi, Bluetooth, VPN, VLANs, or other interfaces
  present.

* Correctly handle edge cases during removal of a network interface.

The fixes are kept as a patch series for clarity.

Signed-off-by: Matt Hoosier <matt.hoosier@garmin.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/meta-networking/recipes-protocols/mdns/files/0008-Mark-deleted-interfaces-as-being-changed.patch b/meta-networking/recipes-protocols/mdns/files/0008-Mark-deleted-interfaces-as-being-changed.patch
new file mode 100644
index 0000000000..fdc5105cb9
--- /dev/null
+++ b/meta-networking/recipes-protocols/mdns/files/0008-Mark-deleted-interfaces-as-being-changed.patch
@@ -0,0 +1,39 @@
+From 0fcc0f210f3a9310a1963de640b384ce866410fd Mon Sep 17 00:00:00 2001
+From: Nate Karstens <nate.karstens@garmin.com>
+Date: Wed, 9 Aug 2017 09:16:58 -0500
+Subject: [PATCH 08/11] Mark deleted interfaces as being changed
+
+Netlink notification handling ignores messages for deleted links,
+RTM_DELLINK. It does handle RTM_GETLINK. According to libnl docu-
+mentation (http://www.infradead.org/~tgr/libnl/doc/route.html)
+RTM_DELLINK can be sent by the kernel, but RTM_GETLINK cannot.
+There was likely a mixup in the original implementation, so this
+change replaces handling for RTM_GETLINK with RTM_DELLINK.
+
+Testing and Verification Instructions:
+  1. Use ip-link to add and remove a VLAN interface and verify
+     that mDNSResponder handles the deleted link.
+
+Upstream-Status: Submitted [dts@apple.com]
+
+Signed-off-by: Nate Karstens <nate.karstens@garmin.com>
+---
+ mDNSPosix/mDNSPosix.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/mDNSPosix/mDNSPosix.c b/mDNSPosix/mDNSPosix.c
+index 798ab10..a8a57df 100644
+--- a/mDNSPosix/mDNSPosix.c
++++ b/mDNSPosix/mDNSPosix.c
+@@ -1163,7 +1163,7 @@ mDNSlocal void          ProcessRoutingNotification(int sd, GenLinkedList *change
+ #endif
+ 
+         // Process the NetLink message
+-        if (pNLMsg->nlmsg_type == RTM_GETLINK || pNLMsg->nlmsg_type == RTM_NEWLINK)
++        if (pNLMsg->nlmsg_type == RTM_DELLINK || pNLMsg->nlmsg_type == RTM_NEWLINK)
+             AddInterfaceIndexToList(changedInterfaces, ((struct ifinfomsg*) NLMSG_DATA(pNLMsg))->ifi_index);
+         else if (pNLMsg->nlmsg_type == RTM_DELADDR || pNLMsg->nlmsg_type == RTM_NEWADDR)
+             AddInterfaceIndexToList(changedInterfaces, ((struct ifaddrmsg*) NLMSG_DATA(pNLMsg))->ifa_index);
+-- 
+2.17.1
+