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, 45 insertions, 0 deletions

diff --git a/meta-networking/recipes-protocols/mdns/files/0009-Fix-possible-NULL-dereference.patch b/meta-networking/recipes-protocols/mdns/files/0009-Fix-possible-NULL-dereference.patch
new file mode 100644
index 0000000000..362d69768e
--- /dev/null
+++ b/meta-networking/recipes-protocols/mdns/files/0009-Fix-possible-NULL-dereference.patch
@@ -0,0 +1,45 @@
+From 38cff19781f81586926b02f0fd1cb36c040395e0 Mon Sep 17 00:00:00 2001
+From: Nate Karstens <nate.karstens@garmin.com>
+Date: Thu, 10 Aug 2017 08:21:53 -0500
+Subject: [PATCH 09/11] Fix possible NULL dereference
+
+Fixes a possible NULL dereference if memory for
+the PosixNetworkInterface could not be allocated.
+Other logic seems to prevent dereferencing this
+variable if NULL, but this instance seems to have
+been overlooked.
+
+Upstream-Status: Submitted [dts@apple.com]
+
+Signed-off-by: Nate Karstens <nate.karstens@garmin.com>
+---
+ mDNSPosix/mDNSPosix.c | 11 +++++++----
+ 1 file changed, 7 insertions(+), 4 deletions(-)
+
+diff --git a/mDNSPosix/mDNSPosix.c b/mDNSPosix/mDNSPosix.c
+index a8a57df..3243ed4 100644
+--- a/mDNSPosix/mDNSPosix.c
++++ b/mDNSPosix/mDNSPosix.c
+@@ -951,12 +951,15 @@ mDNSlocal int SetupOneInterface(mDNS *const m, struct ifi_info *const ifi)
+ 
+     // If interface is a direct link, address record will be marked as kDNSRecordTypeKnownUnique
+     // and skip the probe phase of the probe/announce packet sequence.
+-    intf->coreIntf.DirectLink = mDNSfalse;
++    if (err == 0)
++    {
++        intf->coreIntf.DirectLink = mDNSfalse;
+ #ifdef DIRECTLINK_INTERFACE_NAME
+-    if (strcmp(intfName, STRINGIFY(DIRECTLINK_INTERFACE_NAME)) == 0)
+-        intf->coreIntf.DirectLink = mDNStrue;
++        if (strcmp(intfName, STRINGIFY(DIRECTLINK_INTERFACE_NAME)) == 0)
++            intf->coreIntf.DirectLink = mDNStrue;
+ #endif
+-    intf->coreIntf.SupportsUnicastMDNSResponse = mDNStrue;
++        intf->coreIntf.SupportsUnicastMDNSResponse = mDNStrue;
++    }
+ 
+     // The interface is all ready to go, let's register it with the mDNS core.
+     if (err == 0)
+-- 
+2.17.1
+