Report an ipaddress in a Linux corner case observed on Cisco IOS XR

- we have a default route to an interface
- the route has a configured src
- the src address is not configured on the default interface,
  but the default interface has no address at all

In this case we will choose the src as the ipaddress to report.

lib/ohai/plugins/linux/network.rb

@@ -113,7 +113,15 @@ def check_routing_table(family, iface)
 
         # a sanity check, especially for Linux-VServer, OpenVZ and LXC:
         # don't report the route entry if the src address isn't set on the node
-        next if route_entry[:src] and not iface[route_int][:addresses].has_key? route_entry[:src]
+        # unless the interface has no addresses of this type at all
+        if route_entry[:src]
+          addr = iface[route_int][:addresses]
+          unless addr.nil? || addr.has_key?(route_entry[:src]) ||
+                 addr.values.all? { |a| a['family'] != family[:name] }
+            Ohai::Log.debug("Skipping route entry whose src does not match the interface IP")
+            next
+          end
+        end
 
         iface[route_int][:routes] = Array.new unless iface[route_int][:routes]
         iface[route_int][:routes] << route_entry
@@ -126,6 +134,7 @@ def check_routing_table(family, iface)
   # for information, default routes can be of this form :
   # - default via 10.0.2.4 dev br0
   # - default dev br0  scope link
+  # - default dev eth0  scope link src 1.1.1.1
   # - default via 10.0.3.1 dev eth1  src 10.0.3.2  metric 10
   # - default via 10.0.4.1 dev eth2  src 10.0.4.2  metric 20
 
@@ -310,7 +319,7 @@ def parse_ip_addr_inet6_line(cint, iface, line)
 
   # returns the macaddress for interface from a hash of interfaces (iface elsewhere in this file)
   def get_mac_for_interface(interfaces, interface)
-    interfaces[interface][:addresses].select{|k,v| v["family"]=="lladdr"}.first.first unless interfaces[interface][:flags].include? "NOARP"
+    interfaces[interface][:addresses].select{|k,v| v["family"]=="lladdr"}.first.first unless interfaces[interface][:addresses].nil? || interfaces[interface][:flags].include?("NOARP")
   end
 
   # returns the default route with the lowest metric (unspecified metric is 0)
@@ -332,15 +341,22 @@ def favored_default_route(routes, iface, default_route, family)
         # using the source field when it's specified :
         # 1) in the default route
         # 2) in the route entry used to reach the default gateway
-        r[:src] and # it has a src field
-          iface[r[:dev]] and # the iface exists
-          iface[r[:dev]][:addresses].has_key? r[:src] and # the src ip is set on the node
-          iface[r[:dev]][:addresses][r[:src]][:scope].downcase != "link" and # this isn't a link level addresse
-          ( r[:destination] == "default" or
-            ( default_route[:via] and # the default route has a gateway
-              IPAddress(r[:destination]).include? IPAddress(default_route[:via]) # the route matches the gateway
-              )
+        r[:src] && # it has a src field
+          iface[r[:dev]] && # the iface exists
+          (
+            iface[r[:dev]][:addresses].nil? || # this int has no addresses
+            iface[r[:dev]][:addresses].values.all? { |addr| addr['family'] != family[:name] } || # this int has no ip
+            (
+              iface[r[:dev]][:addresses].has_key?(r[:src]) && # the src ip is set on the node
+              iface[r[:dev]][:addresses][r[:src]][:scope].downcase != "link" # this isn't a link level address
+            )
+          ) && (
+            r[:destination] == "default" ||
+            (
+              default_route[:via] && # the default route has a gateway
+              IPAddress(r[:destination]).include?(IPAddress(default_route[:via])) # the route matches the gateway
             )
+          )
       elsif family[:name] == "inet6"
         # selecting routes for ipv6
         iface[r[:dev]] and # the iface exists

spec/unit/plugins/linux/network_spec.rb

@@ -138,6 +138,14 @@
           TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:21515031 (20.5 MiB)  TX bytes:2052 (2.0 KiB)
+
+fwdintf   Link encap:Ethernet  HWaddr 00:00:00:00:00:0a
+          inet6 addr: fe80::200:ff:fe00:a/64 Scope:Link
+          UP RUNNING NOARP MULTICAST  MTU:1496  Metric:1
+          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
+          TX packets:2 errors:0 dropped:1 overruns:0 carrier:0
+          collisions:0 txqueuelen:1000
+          RX bytes:0 (0.0 B)  TX bytes:140 (140.0 B)
 '
 # Note that ifconfig shows foo:veth0@eth0 but fails to show any address information.
 # This was not a mistake collecting the output and Apparently ifconfig is broken in this regard.
@@ -225,6 +233,8 @@
     link/ether e8:39:35:c5:c8:50 brd ff:ff:ff:ff:ff:ff
     inet 192.168.13.34/24 brd 192.168.13.255 scope global xapi1
        valid_lft forever preferred_lft forever
+13: fwdintf: <MULTICAST,NOARP,UP,LOWER_UP> mtu 1496 qdisc pfifo_fast state UNKNOWN group default qlen 1000
+    link/ether 00:00:00:00:00:0a brd ff:ff:ff:ff:ff:ff
 '
   }
 
@@ -278,6 +288,12 @@
     21468183   159866   0       0       0       0
     TX: bytes  packets  errors  dropped carrier collsns
     2052       6        0       0       0       0
+13: fwdintf: <MULTICAST,NOARP,UP,LOWER_UP> mtu 1496 qdisc pfifo_fast state UNKNOWN mode DEFAULT group default qlen 1000
+    link/ether 00:00:00:00:00:0a brd ff:ff:ff:ff:ff:ff promiscuity 0
+    RX: bytes  packets  errors  dropped overrun mcast
+    0          0        0       0       0       0
+    TX: bytes  packets  errors  dropped carrier collsns
+    140        2        0       1       0       0
 '
   }
 
@@ -375,7 +391,7 @@
       end
 
       it "detects the interfaces" do
-        expect(plugin['network']['interfaces'].keys.sort).to eq(["eth0", "eth0.11", "eth0.151", "eth0.152", "eth0.153", "eth0:5", "eth3", "foo:veth0@eth0", "lo", "ovs-system",  "tun0", "venet0", "venet0:0", "xapi1"])
+        expect(plugin['network']['interfaces'].keys.sort).to eq(["eth0", "eth0.11", "eth0.151", "eth0.152", "eth0.153", "eth0:5", "eth3", "foo:veth0@eth0", "fwdintf", "lo", "ovs-system",  "tun0", "venet0", "venet0:0", "xapi1"])
       end
 
       it "detects the layer one details of an ethernet interface" do
@@ -898,6 +914,54 @@
         end
       end
 
+      describe "with a link level default route to an unaddressed int" do
+        let(:linux_ip_route) {
+'default dev eth3 scope link
+'
+        }
+
+        before(:each) do
+          plugin.run
+        end
+
+        it "completes the run" do
+          expect(Ohai::Log).not_to receive(:debug).with(/Plugin linux::network threw exception/)
+          expect(plugin['network']).not_to be_nil
+        end
+
+        it "sets default_interface" do
+          expect(plugin['network']['default_interface']).to eq('eth3')
+        end
+
+        it "doesn't set ipaddress" do
+          expect(plugin['ipaddress']).to be_nil
+        end
+      end
+
+      describe "with a link level default route with a source" do
+        let(:linux_ip_route) {
+'default dev fwdintf scope link src 2.2.2.2
+'
+        }
+
+        before(:each) do
+          plugin.run
+        end
+
+        it "completes the run" do
+          expect(Ohai::Log).not_to receive(:debug).with(/Plugin linux::network threw exception/)
+          expect(plugin['network']).not_to be_nil
+        end
+
+        it "sets default_interface" do
+          expect(plugin['network']['default_interface']).to eq('fwdintf')
+        end
+
+        it "sets ipaddress" do
+          expect(plugin['ipaddress']).to eq('2.2.2.2')
+        end
+      end
+
       describe "when not having a global scope ipv6 address" do
         let(:linux_ip_route_inet6) {
 'fe80::/64 dev eth0  proto kernel  metric 256