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package memberlist
import (
"fmt"
"log"
"net"
"sync"
"sync/atomic"
"time"
"github.com/armon/go-metrics"
sockaddr "github.com/hashicorp/go-sockaddr"
)
const (
// udpPacketBufSize is used to buffer incoming packets during read
// operations.
udpPacketBufSize = 65536
// udpRecvBufSize is a large buffer size that we attempt to set UDP
// sockets to in order to handle a large volume of messages.
udpRecvBufSize = 2 * 1024 * 1024
)
// NetTransportConfig is used to configure a net transport.
type NetTransportConfig struct {
// BindAddrs is a list of addresses to bind to for both TCP and UDP
// communications.
BindAddrs []string
// BindPort is the port to listen on, for each address above.
BindPort int
// Logger is a logger for operator messages.
Logger *log.Logger
}
// NetTransport is a Transport implementation that uses connectionless UDP for
// packet operations, and ad-hoc TCP connections for stream operations.
type NetTransport struct {
config *NetTransportConfig
packetCh chan *Packet
streamCh chan net.Conn
logger *log.Logger
wg sync.WaitGroup
tcpListeners []*net.TCPListener
udpListeners []*net.UDPConn
shutdown int32
}
// NewNetTransport returns a net transport with the given configuration. On
// success all the network listeners will be created and listening.
func NewNetTransport(config *NetTransportConfig) (*NetTransport, error) {
// If we reject the empty list outright we can assume that there's at
// least one listener of each type later during operation.
if len(config.BindAddrs) == 0 {
return nil, fmt.Errorf("At least one bind address is required")
}
// Build out the new transport.
var ok bool
t := NetTransport{
config: config,
packetCh: make(chan *Packet),
streamCh: make(chan net.Conn),
logger: config.Logger,
}
// Clean up listeners if there's an error.
defer func() {
if !ok {
t.Shutdown()
}
}()
// Build all the TCP and UDP listeners.
port := config.BindPort
for _, addr := range config.BindAddrs {
ip := net.ParseIP(addr)
tcpAddr := &net.TCPAddr{IP: ip, Port: port}
tcpLn, err := net.ListenTCP("tcp", tcpAddr)
if err != nil {
return nil, fmt.Errorf("Failed to start TCP listener on %q port %d: %v", addr, port, err)
}
t.tcpListeners = append(t.tcpListeners, tcpLn)
// If the config port given was zero, use the first TCP listener
// to pick an available port and then apply that to everything
// else.
if port == 0 {
port = tcpLn.Addr().(*net.TCPAddr).Port
}
udpAddr := &net.UDPAddr{IP: ip, Port: port}
udpLn, err := net.ListenUDP("udp", udpAddr)
if err != nil {
return nil, fmt.Errorf("Failed to start UDP listener on %q port %d: %v", addr, port, err)
}
if err := setUDPRecvBuf(udpLn); err != nil {
return nil, fmt.Errorf("Failed to resize UDP buffer: %v", err)
}
t.udpListeners = append(t.udpListeners, udpLn)
}
// Fire them up now that we've been able to create them all.
for i := 0; i < len(config.BindAddrs); i++ {
t.wg.Add(2)
go t.tcpListen(t.tcpListeners[i])
go t.udpListen(t.udpListeners[i])
}
ok = true
return &t, nil
}
// GetAutoBindPort returns the bind port that was automatically given by the
// kernel, if a bind port of 0 was given.
func (t *NetTransport) GetAutoBindPort() int {
// We made sure there's at least one TCP listener, and that one's
// port was applied to all the others for the dynamic bind case.
return t.tcpListeners[0].Addr().(*net.TCPAddr).Port
}
// See Transport.
func (t *NetTransport) FinalAdvertiseAddr(ip string, port int) (net.IP, int, error) {
var advertiseAddr net.IP
var advertisePort int
if ip != "" {
// If they've supplied an address, use that.
advertiseAddr = net.ParseIP(ip)
if advertiseAddr == nil {
return nil, 0, fmt.Errorf("Failed to parse advertise address %q", ip)
}
// Ensure IPv4 conversion if necessary.
if ip4 := advertiseAddr.To4(); ip4 != nil {
advertiseAddr = ip4
}
advertisePort = port
} else {
if t.config.BindAddrs[0] == "0.0.0.0" {
// Otherwise, if we're not bound to a specific IP, let's
// use a suitable private IP address.
var err error
ip, err = sockaddr.GetPrivateIP()
if err != nil {
return nil, 0, fmt.Errorf("Failed to get interface addresses: %v", err)
}
if ip == "" {
return nil, 0, fmt.Errorf("No private IP address found, and explicit IP not provided")
}
advertiseAddr = net.ParseIP(ip)
if advertiseAddr == nil {
return nil, 0, fmt.Errorf("Failed to parse advertise address: %q", ip)
}
} else {
// Use the IP that we're bound to, based on the first
// TCP listener, which we already ensure is there.
advertiseAddr = t.tcpListeners[0].Addr().(*net.TCPAddr).IP
}
// Use the port we are bound to.
advertisePort = t.GetAutoBindPort()
}
return advertiseAddr, advertisePort, nil
}
// See Transport.
func (t *NetTransport) WriteTo(b []byte, addr string) (time.Time, error) {
udpAddr, err := net.ResolveUDPAddr("udp", addr)
if err != nil {
return time.Time{}, err
}
// We made sure there's at least one UDP listener, so just use the
// packet sending interface on the first one. Take the time after the
// write call comes back, which will underestimate the time a little,
// but help account for any delays before the write occurs.
_, err = t.udpListeners[0].WriteTo(b, udpAddr)
return time.Now(), err
}
// See Transport.
func (t *NetTransport) PacketCh() <-chan *Packet {
return t.packetCh
}
// See Transport.
func (t *NetTransport) DialTimeout(addr string, timeout time.Duration) (net.Conn, error) {
dialer := net.Dialer{Timeout: timeout}
return dialer.Dial("tcp", addr)
}
// See Transport.
func (t *NetTransport) StreamCh() <-chan net.Conn {
return t.streamCh
}
// See Transport.
func (t *NetTransport) Shutdown() error {
// This will avoid log spam about errors when we shut down.
atomic.StoreInt32(&t.shutdown, 1)
// Rip through all the connections and shut them down.
for _, conn := range t.tcpListeners {
conn.Close()
}
for _, conn := range t.udpListeners {
conn.Close()
}
// Block until all the listener threads have died.
t.wg.Wait()
return nil
}
// tcpListen is a long running goroutine that accepts incoming TCP connections
// and hands them off to the stream channel.
func (t *NetTransport) tcpListen(tcpLn *net.TCPListener) {
defer t.wg.Done()
// baseDelay is the initial delay after an AcceptTCP() error before attempting again
const baseDelay = 5 * time.Millisecond
// maxDelay is the maximum delay after an AcceptTCP() error before attempting again.
// In the case that tcpListen() is error-looping, it will delay the shutdown check.
// Therefore, changes to maxDelay may have an effect on the latency of shutdown.
const maxDelay = 1 * time.Second
var loopDelay time.Duration
for {
conn, err := tcpLn.AcceptTCP()
if err != nil {
if s := atomic.LoadInt32(&t.shutdown); s == 1 {
break
}
if loopDelay == 0 {
loopDelay = baseDelay
} else {
loopDelay *= 2
}
if loopDelay > maxDelay {
loopDelay = maxDelay
}
t.logger.Printf("[ERR] memberlist: Error accepting TCP connection: %v", err)
time.Sleep(loopDelay)
continue
}
// No error, reset loop delay
loopDelay = 0
t.streamCh <- conn
}
}
// udpListen is a long running goroutine that accepts incoming UDP packets and
// hands them off to the packet channel.
func (t *NetTransport) udpListen(udpLn *net.UDPConn) {
defer t.wg.Done()
for {
// Do a blocking read into a fresh buffer. Grab a time stamp as
// close as possible to the I/O.
buf := make([]byte, udpPacketBufSize)
n, addr, err := udpLn.ReadFrom(buf)
ts := time.Now()
if err != nil {
if s := atomic.LoadInt32(&t.shutdown); s == 1 {
break
}
t.logger.Printf("[ERR] memberlist: Error reading UDP packet: %v", err)
continue
}
// Check the length - it needs to have at least one byte to be a
// proper message.
if n < 1 {
t.logger.Printf("[ERR] memberlist: UDP packet too short (%d bytes) %s",
len(buf), LogAddress(addr))
continue
}
// Ingest the packet.
metrics.IncrCounter([]string{"memberlist", "udp", "received"}, float32(n))
t.packetCh <- &Packet{
Buf: buf[:n],
From: addr,
Timestamp: ts,
}
}
}
// setUDPRecvBuf is used to resize the UDP receive window. The function
// attempts to set the read buffer to `udpRecvBuf` but backs off until
// the read buffer can be set.
func setUDPRecvBuf(c *net.UDPConn) error {
size := udpRecvBufSize
var err error
for size > 0 {
if err = c.SetReadBuffer(size); err == nil {
return nil
}
size = size / 2
}
return err
}
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