Merge pull request #2114 from weaveworks/1972-non-established-proc-conns

Report persistent connections in states other than ESTABLISHED

probe/endpoint/procspy/procnet.go

@@ -5,22 +5,23 @@ import (
 	"net"
 )
 
+// Used to check whether we are parsing a header line
+var slHeader = []byte("sl")
+
 // ProcNet is an iterator to parse /proc/net/tcp{,6} files.
 type ProcNet struct {
 	b                       []byte
 	c                       Connection
-	wantedState             uint
 	bytesLocal, bytesRemote [16]byte
 	seen                    map[uint64]struct{}
 }
 
 // NewProcNet gives a new ProcNet parser.
-func NewProcNet(b []byte, wantedState uint) *ProcNet {
+func NewProcNet(b []byte) *ProcNet {
 	return &ProcNet{
-		b:           b,
-		c:           Connection{},
-		wantedState: wantedState,
-		seen:        map[uint64]struct{}{},
+		b:    b,
+		c:    Connection{},
+		seen: map[uint64]struct{}{},
 	}
 }
 
@@ -33,20 +34,23 @@ again:
 	}
 	b := p.b
 
-	if p.b[2] == 's' {
+	var (
+		sl, local, remote, state, inode []byte
+	)
+
+	sl, b = nextField(b) // 'sl' column
+	if bytes.Equal(sl, slHeader) {
 		// Skip header
 		p.b = nextLine(b)
 		goto again
 	}
-
-	var (
-		local, remote, state, inode []byte
-	)
-	_, b = nextField(b) // 'sl' column
 	local, b = nextField(b)
 	remote, b = nextField(b)
 	state, b = nextField(b)
-	if parseHex(state) != p.wantedState {
+	switch parseHex(state) {
+	// Only process established or half-closed connections
+	case tcpEstablished, tcpFinWait1, tcpFinWait2, tcpCloseWait:
+	default:
 		p.b = nextLine(b)
 		goto again
 	}

probe/endpoint/procspy/procnet_internal_test.go

@@ -13,7 +13,7 @@ func TestProcNet(t *testing.T) {
    2: 0100007F:0019 00000000:0000 01 00000000:00000000 00:00000000 00000000     0        0 10550 1 ffff8800a729b780 100 0 0 10 0                     
    3: A12CF62E:E4D7 57FC1EC0:01BB 01 00000000:00000000 02:000006FA 00000000  1000        0 639474 2 ffff88007e75a740 48 4 26 10 -1                   
 `
-	p := NewProcNet([]byte(testString), tcpEstablished)
+	p := NewProcNet([]byte(testString))
 	expected := []Connection{
 		{
 			LocalAddress:  net.IP([]byte{0, 0, 0, 0}),
@@ -59,12 +59,12 @@ func TestProcNet(t *testing.T) {
 
 func TestTransport6(t *testing.T) {
 	// Abridged copy of my /proc/net/tcp6
-	testString := ` sl  local_address                         remote_address                        st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout Inode
+	testString := `  sl  local_address                         remote_address                        st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout Inode
    0: 00000000000000000000000000000000:19C8 00000000000000000000000000000000:0000 01 00000000:00000000 00:00000000 00000000     0        0 23661201 1 ffff880103fb4800 100 0 0 10 -1
    8: 4500032000BE692B8AE31EBD919D9D10:D61C 5014002A080805400000000015100000:01BB 01 00000000:00000000 02:00000045 00000000  1000        0 36856710 2 ffff88010b796080 22 4 30 8 7
 `
 
-	p := NewProcNet([]byte(testString), tcpEstablished)
+	p := NewProcNet([]byte(testString))
 	expected := []Connection{
 		{
 			// state:         10,
@@ -114,7 +114,7 @@ func TestTransportNonsense(t *testing.T) {
    0: 00000000:A6C0 00000000:0000 01 000000
 broken line
 `
-	p := NewProcNet([]byte(testString), tcpEstablished)
+	p := NewProcNet([]byte(testString))
 	expected := []Connection{
 		{
 			LocalAddress:  net.IP([]byte{0, 0, 0, 0}),
@@ -142,7 +142,7 @@ func TestProcNetFiltersDuplicates(t *testing.T) {
    0: 00000000:A6C0 00000000:0000 01 00000000:00000000 00:00000000 00000000   105        0 5107 1 ffff8800a6aaf040 100 0 0 10 0                      
    1: 00000000:A6C0 00000000:0000 01 00000000:00000000 00:00000000 00000000   105        0 5107 1 ffff8800a6aaf040 100 0 0 10 0                      
 `
-	p := NewProcNet([]byte(testString), tcpEstablished)
+	p := NewProcNet([]byte(testString))
 	expected := Connection{
 		LocalAddress:  net.IP([]byte{0, 0, 0, 0}),
 		LocalPort:     0xa6c0,

probe/endpoint/procspy/spy.go

@@ -8,7 +8,11 @@ import (
 )
 
 const (
-	tcpEstablished = 1 // according to /include/net/tcp_states.h
+	// according to /include/net/tcp_states.h
+	tcpEstablished = 1
+	tcpFinWait1    = 4
+	tcpFinWait2    = 5
+	tcpCloseWait   = 8
 )
 
 // Connection is a (TCP) connection. The Proc struct might not be filled in.

probe/endpoint/procspy/spy_linux.go

@@ -61,7 +61,7 @@ func (s *linuxScanner) Connections(processes bool) (ConnIter, error) {
 	}
 
 	return &pnConnIter{
-		pn:    NewProcNet(buf.Bytes(), tcpEstablished),
+		pn:    NewProcNet(buf.Bytes()),
 		buf:   buf,
 		procs: procs,
 	}, nil