Update gemspec

"pid" is not "process id" in netlink, but rather, "port id". If you bind to a
sockaddr == 0 then Linux automatically assigns your socket a port id - which
happens to be the same as the process ID for the first one concurrently open.

For the second and subsequent concurrently-open sockets, binding 0 (as most
users of this library will do) gets you back a random high-numbered port id.

This change preserves the existing use case (one port open in the process,
binding to 0) while fixing multiple-ports-open-in-the-same-process, socket-is-
passed-in-and-pid-is-not-specified, and specific-pid-is-requested-but-could-
not-bind-to-it.

We're probably still not thread-safe - the seq handling looks dodgy - but at
least now we can use multiple sockets in separate threads and have them all
work.

Using the same socket from multiple threads is a slightly niche use case, and
it's tempting to say "don't do this" instead...

lib/linux/constants.rb

@@ -29,8 +29,8 @@ module Linux
   NETLINK_SCSITRANSPORT	= 18
   NETLINK_ECRYPTFS	= 19
   NETLINK_RDMA      = 20
-  NETLINK_CRYPTO    = 21  
- 
+  NETLINK_CRYPTO    = 21
+
   NLM_F_REQUEST		= 1
   NLM_F_MULTI		= 2
   NLM_F_ACK		= 4
@@ -40,72 +40,74 @@ module Linux
   NLM_F_MATCH		= 0x200
   NLM_F_ATOMIC		= 0x400
   NLM_F_DUMP		= (NLM_F_ROOT|NLM_F_MATCH)
-  
+
   NLM_F_REPLACE		= 0x100
   NLM_F_EXCL		= 0x200
   NLM_F_CREATE		= 0x400
   NLM_F_APPEND		= 0x800
 
   NLMSG_ALIGNTO		= 4	# same on i686 and x86_64
-  
+
   NLMSG_NOOP		= 0x1
   NLMSG_ERROR		= 0x2
   NLMSG_DONE		= 0x3
   NLMSG_OVERRUN		= 0x4
-  
+
   NETLINK_ADD_MEMBERSHIP	= 1
   NETLINK_DROP_MEMBERSHIP	= 2
   NETLINK_PKTINFO		= 3
   NETLINK_BROADCAST_ERROR	= 4
   NETLINK_NO_ENOBUFS		= 5
-  
+  NETLINK_RX_RING	= 6
+  NETLINK_TX_RING = 7
+
   NETLINK_UNCONNECTED		= 0
   NETLINK_CONNECTED		= 1
-  
+
   NLA_F_NESTED			= (1 << 15)
   NLA_F_NET_BYTEORDER		= (1 << 14)
   NLA_TYPE_MASK			= ~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
-  
+
   NLA_ALIGNTO			= 4	# same on i686 and x86_64
-  
+
   # from linux/rtnetlink.h.
   RTM_NEWLINK		= 16
   RTM_DELLINK		= 17
   RTM_GETLINK		= 18
   RTM_SETLINK		= 19
-  
-  RTM_NEWADDR		= 20     
+
+  RTM_NEWADDR		= 20
   RTM_DELADDR		= 21
   RTM_GETADDR		= 22
-  
+
   RTM_NEWROUTE		= 24
   RTM_DELROUTE		= 25
   RTM_GETROUTE		= 26
-  
+
   RTM_NEWNEIGH		= 28
   RTM_DELNEIGH		= 29
   RTM_GETNEIGH		= 30
-  
+
   RTM_NEWRULE		= 32
   RTM_DELRULE		= 33
   RTM_GETRULE		= 34
-  
+
   RTM_NEWQDISC		= 36
   RTM_DELQDISC		= 37
   RTM_GETQDISC		= 38
-  
+
   RTM_NEWTCLASS		= 40
   RTM_DELTCLASS		= 41
   RTM_GETTCLASS		= 42
-  
+
   RTM_NEWTFILTER	= 44
   RTM_DELTFILTER	= 45
   RTM_GETTFILTER	= 46
-  
+
   RTM_NEWACTION		= 48
   RTM_DELACTION		= 49
   RTM_GETACTION		= 50
-  
+
   RTM_NEWPREFIX		= 52
   RTM_GETMULTICAST	= 58
   RTM_GETANYCAST	= 62
@@ -113,16 +115,25 @@ module Linux
   RTM_NEWNEIGHTBL	= 64
   RTM_GETNEIGHTBL	= 66
   RTM_SETNEIGHTBL	= 67
-  
+
   RTM_NEWNDUSEROPT	= 68
 
   RTM_NEWADDRLABEL	= 72
   RTM_DELADDRLABEL	= 73
   RTM_GETADDRLABEL	= 74
-  
+
   RTM_GETDCB		= 78
   RTM_SETDCB		= 79
 
+
+  RTM_NEWNETCONF = 80
+  RTM_GETNETCONF = 82
+
+  RTM_NEWMDB = 84
+  RTM_DELMDB = 85
+  RTM_GETMDB = 86
+
+
   # RT#type
   RTN_UNSPEC		= 0
   RTN_UNICAST		= 1
@@ -136,7 +147,7 @@ module Linux
   RTN_THROW		= 9
   RTN_NAT		= 10
   RTN_XRESOLVE		= 11
-  
+
   # RT#protocol
   RTPROT_UNSPEC		= 0
   RTPROT_REDIRECT	= 1
@@ -152,7 +163,8 @@ module Linux
   RTPROT_XORP		= 14
   RTPROT_NTK		= 15
   RTPROT_DHCP		= 16
-  
+  RTPROT_MROUTED = 17
+
   # RT#scope, IFAddr#scope
   RT_SCOPE_UNIVERSE	= 0
   RT_SCOPE_SITE		= 200
@@ -172,7 +184,7 @@ module Linux
   RT_TABLE_DEFAULT	= 253
   RT_TABLE_MAIN		= 254
   RT_TABLE_LOCAL	= 255
-  
+
   # routing message attributes
   RTA_UNSPEC		= 0
   RTA_DST		= 1
@@ -188,7 +200,13 @@ module Linux
   RTA_CACHEINFO		= 12
   RTA_TABLE		= 15
   RTA_MARK		= 16
-  
+  RTA_MFC_STATS = 17
+
+  # Keys for RT#nh_flags
+  RTNH_F_DEAD	    = 1    # Nexthop is dead (used by multipath)
+  RTNH_F_PERVASIVE	= 2  # Do recursive gateway lookup
+  RTNH_F_ONLINK    = 4   # Gateway is forced on link
+
   # Keys for RT#metrics
   RTAX_UNSPEC		= 0
   RTAX_LOCK		= 1
@@ -205,7 +223,8 @@ module Linux
   RTAX_FEATURES		= 12
   RTAX_RTO_MIN		= 13
   RTAX_INITRWND		= 14
-    
+  RTAX_QUICKACK   = 15
+
   # from linux/if_link.h
   IFLA_UNSPEC		= 0
   IFLA_ADDRESS		= 1
@@ -233,11 +252,29 @@ module Linux
   IFLA_STATS64		= 23
   IFLA_VF_PORTS		= 24
   IFLA_PORT_SELF	= 25
-  IFLA_AF_SPEC    = 26
-  IFLA_GROUP      = 27
-  IFLA_NET_NS_FD  = 28
-  IFLA_EXT_MASK   = 29 
-  IFLA_PROMISCUITY = 30
+  IFLA_AF_SPEC          = 26
+  IFLA_GROUP            = 27
+  IFLA_NET_NS_FD        = 28
+  IFLA_EXT_MASK   = 29
+  IFLA_PROMISCUITY      = 30
+  IFLA_NUM_TX_QUEUES    = 31
+  IFLA_NUM_RX_QUEUES    = 32
+  IFLA_CARRIER          = 33
+  IFLA_PHYS_PORT_ID  = 34
+
+  BRIDGE_MODE_UNSPEC = 0
+  BRIDGE_MODE_HAIRPIN = 1
+
+  IFLA_BRPORT_UNSPEC        = 0
+  IFLA_BRPORT_STATE         = 1 # Spanning tree state
+  IFLA_BRPORT_PRIORITY      = 2 # "             priority
+  IFLA_BRPORT_COST          = 3 # "             cost
+  IFLA_BRPORT_MODE          = 4 # mode (hairpin)
+  IFLA_BRPORT_GUARD         = 5 # bpdu guard
+  IFLA_BRPORT_PROTECT       = 6 # root port protection
+  IFLA_BRPORT_FAST_LEAVE    = 7 # multicast fast leave
+  IFLA_BRPORT_LEARNING      = 8 # mac learning
+  IFLA_BRPORT_UNICAST_FLOOD = 9 # flood unicast traffic
 
   IFLA_INFO_UNSPEC	= 0
   IFLA_INFO_KIND	= 1	# "vlan", "gre" etc
@@ -250,44 +287,52 @@ module Linux
   IFLA_VLAN_FLAGS	= 2	# struct ifla_vlan_flags
   IFLA_VLAN_EGRESS_QOS	= 3	# followed by instance of IFLA_VLAN_QOS_*
   IFLA_VLAN_INGRESS_QOS	= 4	# followed by instance of IFLA_VLAN_QOS_*
-  
+  IFLA_VLAN_PROTOCOL    = 5
+
   IFLA_VLAN_QOS_UNSPEC	= 0
-  IFLA_VLAN_QOS_MAPPING	= 1
-  
+  IFLA_VLAN_QOS_MAPPING = 1
+
   IFLA_MACVLAN_UNSPEC	= 0
   IFLA_MACVLAN_MODE	= 1
-  
+  IFLA_MACVLAN_FLAGS	= 2
+
   MACVLAN_MODE_PRIVATE	= 1
   MACVLAN_MODE_VEPA	= 2
   MACVLAN_MODE_BRIDGE	= 4
   MACVLAN_MODE_PASSTHRU	= 8
-  
+
+  # TODO: VXLAN and VF stuff is missing here
+
   # linux/if_vlan.h
   VLAN_FLAG_REORDER_HDR		= 0x1
   VLAN_FLAG_GVRP		= 0x2
   VLAN_FLAG_LOOSE_BINDING	= 0x4
-  
+  VLAN_FLAG_MVRP          = 0x8
+
   # from linux/if_addr.h
-  IFA_UNSPEC		= 0
-  IFA_ADDRESS		= 1
-  IFA_LOCAL		= 2
-  IFA_LABEL		= 3
-  IFA_BROADCAST		= 4
-  IFA_ANYCAST		= 5
-  IFA_CACHEINFO		= 6
-  IFA_MULTICAST		= 7
+  IFA_UNSPEC      = 0
+  IFA_ADDRESS     = 1
+  IFA_LOCAL       = 2
+  IFA_LABEL       = 3
+  IFA_BROADCAST   = 4
+  IFA_ANYCAST     = 5
+  IFA_CACHEINFO   = 6
+  IFA_MULTICAST   = 7
+  IFA_FLAGS       = 8
 
-  IFA_F_SECONDARY	= 0x01
-  IFA_F_TEMPORARY	= IFA_F_SECONDARY
-  IFA_F_NODAD		= 0x02
-  IFA_F_OPTIMISTIC	= 0x04
-  IFA_F_DADFAILED	= 0x08
-  IFA_F_HOMEADDRESS	= 0x10
-  IFA_F_DEPRECATED	= 0x20
-  IFA_F_TENTATIVE	= 0x40
-  IFA_F_PERMANENT	= 0x80
+  IFA_F_SECONDARY      = 0x01
+  IFA_F_TEMPORARY      = IFA_F_SECONDARY
+  IFA_F_NODAD          = 0x02
+  IFA_F_OPTIMISTIC     = 0x04
+  IFA_F_DADFAILED      = 0x08
+  IFA_F_HOMEADDRESS    = 0x10
+  IFA_F_DEPRECATED     = 0x20
+  IFA_F_TENTATIVE      = 0x40
+  IFA_F_PERMANENT      = 0x80
+  IFA_F_MANAGETEMPADDR = 0x100
+  IFA_F_NOPREFIXROUTE  = 0x200
 
-  # from linux/if_arp.h
+  # from linux/if_arp.h - selected subset
   ARPHRD_NETROM		= 0
   ARPHRD_ETHER		= 1
   ARPHRD_EETHER		= 2
@@ -345,7 +390,7 @@ module Linux
   NF_INET_LOCAL_OUT	= 3
   NF_INET_POST_ROUTING	= 4
   NF_INET_NUMHOOKS	= 5
-    
+
   NFPROTO_UNSPEC	= 0
   NFPROTO_IPV4		= 2
   NFPROTO_ARP		= 3
@@ -357,7 +402,7 @@ module Linux
   IPQ_COPY_NONE		= 0
   IPQ_COPY_META		= 1
   IPQ_COPY_PACKET	= 2
-  
+
   IPQM_MODE		= 17
   IPQM_VERDICT		= 18
   IPQM_PACKET		= 19
@@ -366,22 +411,22 @@ module Linux
   # linux/netfilter_ipv4/ipt_ULOG.h
   ULOG_MAC_LEN		= 80
   ULOG_PREFIX_LEN	= 32
-  
+
   # linux/netfilter/x_tables.h
   XT_TABLE_MAXNAMELEN	= 32
-  
+
   XT_CONTINUE		= 0xffffffff
   XT_RETURN		= (-NF_REPEAT - 1)
 
   XT_INV_PROTO		= 0x40
-  
+
   # linux/netfilter_ipv4/ip_tables.h
   IPT_TABLE_MAXNAMELEN	= XT_TABLE_MAXNAMELEN
-  
+
   IPT_F_FRAG		= 0x01
   IPT_F_GOTO		= 0x02
   IPT_F_MASK		= 0x03
-  
+
   IPT_INV_VIA_IN	= 0x01
   IPT_INV_VIA_OUT	= 0x02
   IPT_INV_TOS		= 0x04
@@ -390,17 +435,17 @@ module Linux
   IPT_INV_FRAG		= 0x20
   IPT_INV_PROTO		= XT_INV_PROTO
   IPT_INV_MASK		= 0x7f
-  
+
   IPT_BASE_CTL			= 64
 
   IPT_SO_SET_REPLACE		= IPT_BASE_CTL
   IPT_SO_SET_ADD_COUNTERS	= IPT_BASE_CTL + 1
-  
+
   IPT_SO_GET_INFO		= IPT_BASE_CTL
   IPT_SO_GET_ENTRIES		= IPT_BASE_CTL + 1
   IPT_SO_GET_REVISION_MATCH	= IPT_BASE_CTL + 2
   IPT_SO_GET_REVISION_TARGET	= IPT_BASE_CTL + 3
-  
+
   IPT_CONTINUE			= XT_CONTINUE
   IPT_RETURN			= XT_RETURN
 end

lib/linux/netlink/message.rb

@@ -187,7 +187,7 @@ module Netlink
             warn "Duplicate attribute #{name} (#{code}): #{attrs[name].inspect} -> #{val.inspect}" if attrs[name]
             attrs[name] = val
           else
-            warn "Unknown attribute #{code}, in class #{self}, value #{val.inspect}"
+            warn "Unknown attribute #{code}, in class #{self}, value #{val.inspect}" if $DEBUG
             attrs[code] = val
           end
         end

lib/linux/netlink/nlsocket.rb

@@ -25,7 +25,7 @@ module Netlink
     # Check the sockaddr on a received message. Raises an error if the AF
     # is not AF_NETLINK or the PID is not 0 (this is important for security)
     def self.check_sockaddr(str)
-      af, pad, pid, groups = str.unpack(SOCKADDR_PACK)
+      af, _, pid, _ = str.unpack(SOCKADDR_PACK)
       raise "Bad AF #{af}!" if af != Socket::AF_NETLINK
       raise "Bad PID #{pid}!" if pid != 0
     end
@@ -58,14 +58,16 @@ module Netlink
     #   :timeout => N (seconds, default to DEFAULT_TIMEOUT. Pass nil for no timeout)
     #   :junk_handler => lambda { ... } for unexpected packets
     def initialize(opt)
-      @socket ||= opt[:socket] || ::Socket.new(
+      @socket = opt[:socket] || ::Socket.new(
         Socket::AF_NETLINK,
         Socket::SOCK_DGRAM,
         opt[:protocol] || (raise "Missing :protocol")
       )
       @socket.bind(NLSocket.sockaddr(opt)) unless opt[:socket]
       @seq = opt[:seq] || Time.now.to_i
-      @pid = opt[:pid] || $$
+
+      @pid = @socket.getsockname.unpack(SOCKADDR_PACK)[2]
+
       @timeout = opt.has_key?(:timeout) ? opt[:timeout] : DEFAULT_TIMEOUT
       if opt.has_key?(:junk_handler)
         @junk_handler = opt[:junk_handler]
@@ -75,7 +77,7 @@ module Netlink
         }
       end
     end
-    
+
     # Close the Netlink socket
     def close
       @socket.close
@@ -85,7 +87,7 @@ module Netlink
     def next_seq
       @seq = (@seq + 1) & 0xffffffff
     end
-    
+
     # Add a header and send a single message over the socket.
     #   type:: the message type code
     #   msg:: the message to send (without header)
@@ -135,8 +137,8 @@ module Netlink
     # (Compare: rtnl_talk in lib/libnetlink.c, with answer=NULL)
     def cmd(type, msg, flags=NLM_F_REQUEST, resp_type=NLMSG_ERROR, timeout=@timeout, sockaddr=SOCKADDR_DEFAULT)
       send_request(type, msg, flags|NLM_F_ACK, sockaddr)
-      receive_responses(true, timeout) do |type,msg|
-        return msg if type == resp_type
+      receive_responses(true, timeout) do |rtype,rmsg|
+        return rmsg if rtype == resp_type
         false
       end
     end
@@ -144,7 +146,7 @@ module Netlink
     # Discard all waiting messages
     def drain
       while select([@socket], nil, nil, 0)
-        mesg, sender, rflags, controls = @socket.recvmsg
+        mesg, _, _, _ = @socket.recvmsg
         raise EOFError unless mesg
       end
     end
@@ -203,13 +205,13 @@ module Netlink
         end
       end
     end
-    
+
     # Receive one datagram from kernel. Validates the sender, and returns
     # the raw binary message. Raises an exception on timeout or if the
     # kernel closes the socket.
     def recvmsg(timeout=@timeout)
       if select([@socket], nil, nil, timeout)
-        mesg, sender, rflags, controls = @socket.recvmsg
+        mesg, sender, _, _ = @socket.recvmsg
         raise EOFError unless mesg
         sender = sender.to_sockaddr if sender.respond_to? :to_sockaddr
         NLSocket.check_sockaddr(sender)

lib/linux/netlink/route/addr_handler.rb

@@ -24,6 +24,10 @@ module Netlink
         :pack   => lambda { |val,obj| val.to_a.pack("L*") },
         :unpack => lambda { |str,obj| IFACacheInfo.new(*(str.unpack("L*"))) }
     rtattr :multicast, IFA_MULTICAST, :l3addr
+
+    # TODO: is there any difference between flags and ifa_flags? The latter only
+    # shows up on newer kernels
+    rtattr :ifa_flags, IFA_FLAGS, :uint
   end
 
   module Route

lib/linux/netlink/route/link_handler.rb

@@ -65,6 +65,9 @@ module Netlink
     rtattr :net_ns_fd, IFLA_NET_NS_FD
     rtattr :ext_mask, IFLA_EXT_MASK   
     rtattr :promiscuity, IFLA_PROMISCUITY
+    rtattr :num_tx_queues, IFLA_NUM_TX_QUEUES
+    rtattr :num_rx_queues, IFLA_NUM_RX_QUEUES
+    rtattr :carrier, IFLA_CARRIER
  
     # Return the best stats available (64bit or 32bit)
     def stats
@@ -119,6 +122,7 @@ module Netlink
       :unpack => lambda { |str,obj| VlanFlags.parse(str) }
     rtattr :egress_qos, IFLA_VLAN_EGRESS_QOS
     rtattr :ingress_qos, IFLA_VLAN_INGRESS_QOS
+    rtattr :protocol, IFLA_VLAN_PROTOCOL, :ushort
   end
 
   module Route

lib/linux/netlink/route/vlan_handler.rb

@@ -8,12 +8,12 @@ module Netlink
       def clear_cache
         # No cache
       end
-      
+
       def list(filter={}, &blk)
         @rtsocket.link.list(filter.merge(:kind=>"vlan"))
       end
       alias :each :list
-            
+
       # Higher-level API to manipulate VLAN interface.
       #    nl.vlans.add(
       #      :link=>"lo",
@@ -24,15 +24,15 @@ module Netlink
       def add(opt)
         @rtsocket.link.add(vlan_options(opt))
       end
-      
+
       def change(opt)
         @rtsocket.link.change(vlan_options(opt))
       end
-      
+
       def replace(opt)
         @rtsocket.link.replace(vlan_options(opt))
       end
-      
+
       # Delete vlan given :link and :vlan_id. If you want to delete
       # by :index then call link.delete instead.
       def delete(opt)
@@ -59,6 +59,7 @@ module Netlink
         end
         li.data.egress_qos = opt.delete(:egress_qos) if opt.has_key?(:egress_qos)
         li.data.ingress_qos = opt.delete(:ingress_qos) if opt.has_key?(:ingress_qos)
+        li.data.protocol = opt.delete(:protocol) if opt.has_key?(:protocol)
         opt
       end
     end

netlinkrb.gemspec

@@ -5,9 +5,9 @@ $:.unshift lib unless $:.include? lib
 
 Gem::Specification.new do |s|
   s.name = "netlinkrb"
-  s.version = "0.12"
+  s.version = "0.16"
   s.platform = Gem::Platform::RUBY
-  s.authors = ["Brian Candler", "Matthew Bloch", "Patrick Cherry", "Alex Young"]
+  s.authors = ["Brian Candler", "Matthew Bloch", "Patrick Cherry", "Alex Young", "Nicholas Thomas"]
   s.email = ["matthew@bytemark.co.uk"]
   s.summary = "Interface to Linux' Netlink API"
   s.description = "Ruby native interface to the Netlink API which avoids shelling out to command-line tools as much as possible."

test/t_route.rb

@@ -1,10 +1,6 @@
-require File.join(File.dirname(__FILE__), 'test_helper')
+require File.expand_path( File.join(File.dirname(__FILE__), 'test_helper') )
 require 'linux/netlink/route'
 
-# Note: multiple sockets bound to the same PID seem to cause timeout problems.
-# (Should we use different algorithm for generating the PID? PID + seq?)
-$ip ||= Linux::Netlink::Route::Socket.new
-
 #
 # Ruby 1.8.7 appears to lack the KeyError constant.
 #
@@ -15,21 +11,57 @@ end
 class TestAddr < Test::Unit::TestCase
   context "With netlink route socket" do
     setup do
-      @ip = $ip
+      @ip =  Linux::Netlink::Route::Socket.new
+      @ifname = nil
     end
 
     teardown do
       begin
-        delete_test_interface
+        delete_test_interface(@ifname)
       rescue KeyError, IndexError
         # Do nothing
       end
+
+      @ip.close
     end
 
     test "Read link type" do
       assert_equal Linux::ARPHRD_LOOPBACK, @ip.link["lo"].type
     end
 
+    test "Both sockets work if two are open at the same time" do
+      begin
+        @ip2 = Linux::Netlink::Route::Socket.new
+
+        assert_kind_of Enumerable, @ip.route.list
+        assert_kind_of Enumerable, @ip2.route.list
+      ensure
+        @ip2.close
+      end
+    end
+
+    test "massively parallel IP address addition" do
+      @ifname = create_test_interface
+
+      ips = (10..20).map {|y| (1..254).map {|z| "10.100.#{y}.#{z}" } }.flatten.compact
+
+      threads = ips.map {|ip|
+        Thread.new {
+          Linux::Netlink::Route::Socket.new.addr.add(
+            :index => @ifname,
+            :local => ip,
+            :prefixlen => 8
+          )
+        }
+      }
+
+      threads.map(&:join)
+      created = @ip.addr.list(:index => @ifname, :family => Socket::AF_INET).
+        map {|ifaddr| ifaddr.address.to_s }
+
+      ips.each {|ip| assert created.include?( ip ), "#{ip} was not created" }
+    end
+
     def create_test_interface(ifname = "test_#{$$}")
       begin
         @ip.link.add(
@@ -38,28 +70,29 @@ class TestAddr < Test::Unit::TestCase
             :kind => "dummy"
           )
         )
+      rescue Errno::EOPNOTSUPP
+        # Ugh, fall back to eth0
+        ifname = "eth0"
       rescue Errno::EPERM => err
-        if self.respond_to?(:skip)
-          skip err.to_s
-        else
-          puts "Skipping #{self.method_name} -- #{err.to_s}"
-          return nil
-        end
+        do_skip err.to_s
       end
 
       return ifname
     end
 
     def set_interface_up(ifname)
-        link = @ip.link.list.find{|l| l.ifname == ifname}
+      link = @ip.link.list.find{|l| l.ifname == ifname}
 
-        #
-        # Bring the link up
-        #
-        @ip.link.change(
-         :index => link.index,
-         :flags => link.flags | Linux::IFF_UP | Linux::IFF_RUNNING
-       )
+      return if link.nil?
+      return unless link.linkinfo and "dummy" == link.linkinfo.kind
+
+      #
+      # Bring the link up
+      #
+      @ip.link.change(
+        :index => link.index,
+        :flags => link.flags | Linux::IFF_UP | Linux::IFF_RUNNING
+      )
 
       link = @ip.link.list.find{|l| l.ifname == ifname}
 
@@ -71,6 +104,7 @@ class TestAddr < Test::Unit::TestCase
       link = @ip.link.list.find{|l| l.ifname == ifname}
 
       return if link.nil?
+      return unless link.linkinfo and "dummy" == link.linkinfo.kind
       return unless link.flags == (link.flags | Linux::IFF_UP | Linux::IFF_RUNNING)
 
       #
@@ -87,19 +121,39 @@ class TestAddr < Test::Unit::TestCase
       assert_equal(0, link.flags & Linux::IFF_RUNNING, "Link still has the IFF_RUNNING flag set") 
     end
 
-    def delete_test_interface(ifname = "test_#{$$}")
+    def delete_test_interface(ifname) 
+      unless @ip.link[ifname] and @ip.link[ifname].linkinfo and "dummy" == @ip.link[ifname].linkinfo.kind
+        return nil
+      end
+
       begin
         set_interface_down(ifname)
       ensure
         @ip.link.delete(:index => ifname)
       end
     end
-      
-    test "Add and remove dummy interface" do
-      ifname = create_test_interface
-      return if ifname.nil?
 
-      delete_test_interface(ifname)
+    def do_skip(msg)
+      if self.respond_to?(:skip)
+        skip msg
+      else
+        puts "Skipping #{self.method_name} -- #{msg}"
+      end
+      return nil
+    end
+
+    test "Add and remove dummy interface" do
+      @ifname = create_test_interface
+      return if @ifname.nil?
+      
+      link = @ip.link.list.find{|x| x.ifname == @ifname} 
+      return if link.nil?
+
+      unless link.linkinfo and "dummy" == link.linkinfo.kind
+        return do_skip("Could not create dummy interface")
+      end
+
+      delete_test_interface(@ifname)
     end
     
     def addrlist(opt = {:index=>"lo"})
@@ -107,23 +161,26 @@ class TestAddr < Test::Unit::TestCase
     end
 
     def add_and_remove_addr(testaddr, pfx)
-      ifname = create_test_interface
-      return if ifname.nil?
+      @ifname = create_test_interface
+      return if @ifname.nil?
 
-      addrs1 = addrlist({:index => ifname})
+      link = @ip.link.list.find{|x| x.ifname == @ifname} 
+      return if link.nil?
+      
+      addrs1 = addrlist({:index => @ifname})
       assert !addrs1.include?(testaddr)
 
-      @ip.addr.add(:index=>ifname, :local=>testaddr, :prefixlen=>pfx)
+      @ip.addr.add(:index=>@ifname, :local=>testaddr, :prefixlen=>pfx)
       assert_raises(Errno::EEXIST) {
-        @ip.addr.add(:index=>ifname, :local=>testaddr, :prefixlen=>pfx)
+        @ip.addr.add(:index=>@ifname, :local=>testaddr, :prefixlen=>pfx)
       }
 
-      addrs2 = addrlist({:index => ifname})
+      addrs2 = addrlist({:index => @ifname})
       assert addrs2.include?(testaddr), "#{addrs2.inspect} doesn't include #{testaddr}"
       
-      @ip.addr.delete(:index=>ifname, :local=>testaddr, :prefixlen=>pfx)
+      @ip.addr.delete(:index=>@ifname, :local=>testaddr, :prefixlen=>pfx)
       
-      addrs3 = addrlist({:index => ifname})
+      addrs3 = addrlist({:index => @ifname})
       assert_equal addrs1, addrs3
     end
 
@@ -158,22 +215,24 @@ class TestAddr < Test::Unit::TestCase
     end
   
     test "Add and remove vlan" do
-      ifname = create_test_interface
-      return if ifname.nil?
+      @ifname = create_test_interface
+      return if @ifname.nil?
 
-      vlans1 = vlanlist(ifname)
+      link = @ip.link.list.find{|x| x.ifname == @ifname}
+      return if link.nil?
+
+      vlans1 = vlanlist(@ifname)
       assert !vlans1.include?(1234)
 
-      @ip.vlan.add(:link=>ifname, :vlan_id=>1234)
+      @ip.vlan.add(:link=>@ifname, :vlan_id=>1234)
 
-      vlans2 = vlanlist(ifname)
+      vlans2 = vlanlist(@ifname)
       assert vlans2.include?(1234)
 
-      @ip.vlan.delete(:link=>ifname, :vlan_id=>1234)
+      @ip.vlan.delete(:link=>@ifname, :vlan_id=>1234)
 
-      vlans3 = vlanlist(ifname)
+      vlans3 = vlanlist(@ifname)
       assert_equal vlans1, vlans3
-      @ip.link.delete(:index => ifname)
     end
 
     def routes
@@ -191,13 +250,17 @@ class TestAddr < Test::Unit::TestCase
     end
     
     def add_and_remove_route(info)
-      ifname = create_test_interface
-      return if ifname.nil?
+      @ifname = create_test_interface
+      return if @ifname.nil?
 
-      set_interface_up(ifname) 
+      set_interface_up(@ifname) 
 
-      info[:oif] = ifname
-      ifidx = @ip.link.list.find{|x| x.ifname == info[:oif]}.index
+      info[:oif] = @ifname
+
+      link = @ip.link.list.find{|x| x.ifname == info[:oif]}
+      return if link.nil?
+
+      ifidx = link.index
 
       assert_equal 0, routes.select { |x| x == [info[:dst], info[:dst_len], ifidx] }.size