Ensures that ARP facts are returned only on EC2 hosts

ARP facts on large network might lead to inconstant values
as we are always using the first ARP entry from the output of the ARP
command

Signed-off-by: Ohad Levy <ohadlevy@gmail.com>

2 files changed, 13 insertions, 15 deletions

diff --git a/lib/facter/arp.rb b/lib/facter/arp.rb
index 5035ad0..0a7cf67 100644
--- a/lib/facter/arp.rb
+++ b/lib/facter/arp.rb
@@ -3,14 +3,17 @@ require 'facter/util/ip'
 Facter.add(:arp) do
   confine :kernel => :linux
   setcode do
-    arp = []
     output = Facter::Util::Resolution.exec('arp -a')
     if not output.nil?
+      arp = ""
       output.each_line do |s|
-        arp.push($1) if s =~ /^\S+\s\S+\s\S+\s(\S+)\s\S+\s\S+\s\S+$/
+        if s =~ /^\S+\s\S+\s\S+\s(\S+)\s\S+\s\S+\s\S+$/
+          arp = $1
+          break # stops on the first match
+        end
       end
     end
-    arp[0]
+    EC2_ARP == arp ? arp : nil
   end
 end
 
@@ -18,7 +21,8 @@ Facter::Util::IP.get_interfaces.each do |interface|
   Facter.add("arp_" + Facter::Util::IP.alphafy(interface)) do
     confine :kernel => :linux
     setcode do
-      Facter::Util::IP.get_arp_value(interface)
+      arp = Facter::Util::IP.get_arp_value(interface)
+      EC2_ARP == arp ? arp : nil
     end
   end
 end
diff --git a/lib/facter/ec2.rb b/lib/facter/ec2.rb
index 29b2a1c..693e78e 100644
--- a/lib/facter/ec2.rb
+++ b/lib/facter/ec2.rb
@@ -6,9 +6,11 @@
 require 'open-uri'
 require 'socket'
 
-EC2_ADDR = "169.254.169.254"
+EC2_ADDR         = "169.254.169.254"
 EC2_METADATA_URL = "http://#{EC2_ADDR}/2008-02-01/meta-data"
 EC2_USERDATA_URL = "http://#{EC2_ADDR}/2008-02-01/user-data"
+EC2_ARP          = "fe:ff:ff:ff:ff:ff"
+EC2_EUCA_MAC     = %r{^[dD]0:0[dD]:}
 
 def can_metadata_connect?(addr, port, timeout=2)
   t = Socket.new(Socket::Constants::AF_INET, Socket::Constants::SOCK_STREAM, 0)
@@ -61,19 +63,11 @@ def userdata()
 end
 
 def has_euca_mac?
-  if Facter.value(:macaddress) =~ /^[dD]0:0[dD]:/
-    return true
-  else
-    return false
-  end
+  !!(Facter.value(:macaddress) =~ EC2_EUCA_MAC)
 end
 
 def has_ec2_arp?
-  if Facter.value(:arp) == 'fe:ff:ff:ff:ff:ff'
-    return true
-  else
-    return false
-  end
+  !!(Facter.value(:arp) == EC2_ARP)
 end
 
 if (has_euca_mac? || has_ec2_arp?) && can_metadata_connect?(EC2_ADDR,80)