Parse link statistics (#118)

Signed-off-by: Alessandro Boch <aboch@docker.com>

link.go

@@ -31,6 +31,7 @@ type LinkAttrs struct {
 	MasterIndex  int         // must be the index of a bridge
 	Namespace    interface{} // nil | NsPid | NsFd
 	Alias        string
+	Statistics   *LinkStatistics
 }
 
 // NewLinkAttrs returns LinkAttrs structure filled with default values
@@ -40,6 +41,35 @@ func NewLinkAttrs() LinkAttrs {
 	}
 }
 
+/*
+Ref: struct rtnl_link_stats {...}
+*/
+type LinkStatistics struct {
+	RxPackets         uint32
+	TxPackets         uint32
+	RxBytes           uint32
+	TxBytes           uint32
+	RxErrors          uint32
+	TxErrors          uint32
+	RxDropped         uint32
+	TxDropped         uint32
+	Multicast         uint32
+	Collisions        uint32
+	RxLengthErrors    uint32
+	RxOverErrors      uint32
+	RxCrcErrors       uint32
+	RxFrameErrors     uint32
+	RxFifoErrors      uint32
+	RxMissedErrors    uint32
+	TxAbortedErrors   uint32
+	TxCarrierErrors   uint32
+	TxFifoErrors      uint32
+	TxHeartbeatErrors uint32
+	TxWindowErrors    uint32
+	RxCompressed      uint32
+	TxCompressed      uint32
+}
+
 // Device links cannot be created via netlink. These links
 // are links created by udev like 'lo' and 'etho0'
 type Device struct {

link_linux.go

@@ -12,6 +12,8 @@ import (
 	"github.com/vishvananda/netlink/nl"
 )
 
+const SizeofLinkStats = 0x5c
+
 var native = nl.NativeEndian()
 var lookupByDump = false
 
@@ -943,6 +945,8 @@ func linkDeserialize(m []byte) (Link, error) {
 			base.TxQLen = int(native.Uint32(attr.Value[0:4]))
 		case syscall.IFLA_IFALIAS:
 			base.Alias = string(attr.Value[:len(attr.Value)-1])
+		case syscall.IFLA_STATS:
+			base.Statistics = parseLinkStats(attr.Value[:])
 		}
 	}
 	// Links that don't have IFLA_INFO_KIND are hardware devices
@@ -1360,3 +1364,7 @@ func parseGretapData(link Link, data []syscall.NetlinkRouteAttr) {
 		}
 	}
 }
+
+func parseLinkStats(data []byte) *LinkStatistics {
+	return (*LinkStatistics)(unsafe.Pointer(&data[0:SizeofLinkStats][0]))
+}

link_test.go

@@ -779,3 +779,51 @@ func TestLinkSubscribe(t *testing.T) {
 		t.Fatal("Del update not received as expected")
 	}
 }
+
+func TestLinkStats(t *testing.T) {
+	defer setUpNetlinkTest(t)()
+
+	// Create a veth pair and verify the cross-stats once both
+	// ends are brought up and some ICMPv6 packets are exchanged
+	v0 := "v0"
+	v1 := "v1"
+
+	vethLink := &Veth{LinkAttrs: LinkAttrs{Name: v0}, PeerName: v1}
+	if err := LinkAdd(vethLink); err != nil {
+		t.Fatal(err)
+	}
+
+	veth0, err := LinkByName(v0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := LinkSetUp(veth0); err != nil {
+		t.Fatal(err)
+	}
+
+	veth1, err := LinkByName(v1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := LinkSetUp(veth1); err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(2 * time.Second)
+
+	// verify statistics
+	veth0, err = LinkByName(v0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	veth1, err = LinkByName(v1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	v0Stats := veth0.Attrs().Statistics
+	v1Stats := veth1.Attrs().Statistics
+	if v0Stats.RxPackets != v1Stats.TxPackets || v0Stats.TxPackets != v1Stats.RxPackets ||
+		v0Stats.RxBytes != v1Stats.TxBytes || v0Stats.TxBytes != v1Stats.RxBytes {
+		t.Fatalf("veth ends counters differ:\n%v\n%v", v0Stats, v1Stats)
+	}
+}