Update github.com/mdlayher/netlink with code simplifications

vendor/github.com/mdlayher/netlink/conn.go

@@ -3,7 +3,6 @@ package netlink
 import (
 	"errors"
 	"math/rand"
-	"sync"
 	"sync/atomic"
 
 	"golang.org/x/net/bpf"
@@ -27,11 +26,8 @@ type Conn struct {
 	// numbers when Conn.Send is called.
 	seq *uint32
 
-	// pid is an atomically set/loaded integer which is set to the PID assigned
+	// pid is the PID assigned by netlink.
-	// by netlink, when netlink sends its first response message.  pidOnce performs
+	pid uint32
-	// the assignment exactl once.
-	pid     *uint32
-	pidOnce sync.Once
 }
 
 // An osConn is an operating-system specific implementation of netlink
@@ -50,22 +46,22 @@ type osConn interface {
 // configuration will be used.
 func Dial(proto int, config *Config) (*Conn, error) {
 	// Use OS-specific dial() to create osConn
-	c, err := dial(proto, config)
+	c, pid, err := dial(proto, config)
 	if err != nil {
 		return nil, err
 	}
 
-	return newConn(c), nil
+	return newConn(c, pid), nil
 }
 
 // newConn is the internal constructor for Conn, used in tests.
-func newConn(c osConn) *Conn {
+func newConn(c osConn, pid uint32) *Conn {
 	seq := rand.Uint32()
 
 	return &Conn{
 		c:   c,
 		seq: &seq,
-		pid: new(uint32),
+		pid: pid,
 	}
 }
 
@@ -128,7 +124,7 @@ func (c *Conn) Send(m Message) (Message, error) {
 	}
 
 	if m.Header.PID == 0 {
-		m.Header.PID = atomic.LoadUint32(c.pid)
+		m.Header.PID = c.pid
 	}
 
 	if err := c.c.Send(m); err != nil {
@@ -142,10 +138,6 @@ func (c *Conn) Send(m Message) (Message, error) {
 // handled transparently and returned as a single slice of Messages, with the
 // final empty "multi-part done" message removed.
 //
-// If a PID has not yet been assigned to this Conn by netlink, the PID will
-// be set from the first received message.  This PID will be used in all
-// subsequent communications with netlink.
-//
 // If any of the messages indicate a netlink error, that error will be returned.
 func (c *Conn) Receive() ([]Message, error) {
 	msgs, err := c.receive()
@@ -153,16 +145,6 @@ func (c *Conn) Receive() ([]Message, error) {
 		return nil, err
 	}
 
-	if len(msgs) > 0 {
-		// netlink multicast messages from kernel have PID of 0, so don't
-		// assign 0 as the expected PID for next messages
-		if pid := msgs[0].Header.PID; pid != 0 {
-			c.pidOnce.Do(func() {
-				atomic.StoreUint32(c.pid, pid)
-			})
-		}
-	}
-
 	// Trim the final message with multi-part done indicator if
 	// present
 	if m := msgs[len(msgs)-1]; m.Header.Flags&HeaderFlagsMulti != 0 && m.Header.Type == HeaderTypeDone {

vendor/github.com/mdlayher/netlink/conn_linux.go

@@ -29,21 +29,22 @@ type conn struct {
 type socket interface {
 	Bind(sa unix.Sockaddr) error
 	Close() error
+	Getsockname() (unix.Sockaddr, error)
 	Recvmsg(p, oob []byte, flags int) (n int, oobn int, recvflags int, from unix.Sockaddr, err error)
 	Sendmsg(p, oob []byte, to unix.Sockaddr, flags int) error
 	SetSockopt(level, name int, v unsafe.Pointer, l uint32) error
 }
 
 // dial is the entry point for Dial.  dial opens a netlink socket using
-// system calls.
+// system calls, and returns its PID.
-func dial(family int, config *Config) (*conn, error) {
+func dial(family int, config *Config) (*conn, uint32, error) {
 	fd, err := unix.Socket(
 		unix.AF_NETLINK,
 		unix.SOCK_RAW,
 		family,
 	)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	return bind(&sysSocket{fd: fd}, config)
@@ -51,7 +52,7 @@ func dial(family int, config *Config) (*conn, error) {
 
 // bind binds a connection to netlink using the input socket, which may be
 // a system call implementation or a mocked one for tests.
-func bind(s socket, config *Config) (*conn, error) {
+func bind(s socket, config *Config) (*conn, uint32, error) {
 	if config == nil {
 		config = &Config{}
 	}
@@ -61,17 +62,26 @@ func bind(s socket, config *Config) (*conn, error) {
 		Groups: config.Groups,
 	}
 
+	// Socket must be closed in the event of any system call errors, to avoid
+	// leaking file descriptors.
+
 	if err := s.Bind(addr); err != nil {
-		// Since this never returns conn (and as such, the caller cannot close it),
-		// close the socket here in the event of a failure to bind.
 		_ = s.Close()
-		return nil, err
+		return nil, 0, err
 	}
 
+	sa, err := s.Getsockname()
+	if err != nil {
+		_ = s.Close()
+		return nil, 0, err
+	}
+
+	pid := sa.(*unix.SockaddrNetlink).Pid
+
 	return &conn{
 		s:  s,
 		sa: addr,
-	}, nil
+	}, pid, nil
 }
 
 // Send sends a single Message to netlink.
@@ -201,6 +211,7 @@ type sysSocket struct {
 
 func (s *sysSocket) Bind(sa unix.Sockaddr) error         { return unix.Bind(s.fd, sa) }
 func (s *sysSocket) Close() error                        { return unix.Close(s.fd) }
+func (s *sysSocket) Getsockname() (unix.Sockaddr, error) { return unix.Getsockname(s.fd) }
 func (s *sysSocket) Recvmsg(p, oob []byte, flags int) (int, int, int, unix.Sockaddr, error) {
 	return unix.Recvmsg(s.fd, p, oob, flags)
 }

vendor/vendor.json

@@ -51,10 +51,10 @@
 			"revisionTime": "2016-04-24T11:30:07Z"
 		},
 		{
-			"checksumSHA1": "yDvo49XwrEOOzk4g5eMtz7aZ1RY=",
+			"checksumSHA1": "r3t+HDvOEQVCaLjuMT8rl6opbNQ=",
 			"path": "github.com/mdlayher/netlink",
-			"revision": "11047e3e3daa32f7b757bc9ab59c413cadeccfa1",
+			"revision": "343c07bd16ebbc714f19c528a6deb6723ace06f3",
-			"revisionTime": "2017-03-02T15:49:27Z"
+			"revisionTime": "2017-03-10T17:31:27Z"
 		},
 		{
 			"checksumSHA1": "+2roeIWCAjCC58tZcs12Vqgf1Io=",