For more deeper understanding https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/
206 lines
5.5 KiB
Go
206 lines
5.5 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2017 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package http
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import (
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"fmt"
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"io"
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"net"
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"os"
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"sync"
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"syscall"
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)
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type acceptResult struct {
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conn net.Conn
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err error
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}
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// httpListener - HTTP listener capable of handling multiple server addresses.
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type httpListener struct {
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mutex sync.Mutex // to guard Close() method.
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tcpListeners []*net.TCPListener // underlaying TCP listeners.
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acceptCh chan acceptResult // channel where all TCP listeners write accepted connection.
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doneCh chan struct{} // done channel for TCP listener goroutines.
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}
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// isRoutineNetErr returns true if error is due to a network timeout,
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// connect reset or io.EOF and false otherwise
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func isRoutineNetErr(err error) bool {
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if err == nil {
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return false
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}
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if nErr, ok := err.(*net.OpError); ok {
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// Check if the error is a tcp connection reset
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if syscallErr, ok := nErr.Err.(*os.SyscallError); ok {
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if errno, ok := syscallErr.Err.(syscall.Errno); ok {
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return errno == syscall.ECONNRESET
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}
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}
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// Check if the error is a timeout
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return nErr.Timeout()
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}
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// check for io.EOF and also some times io.EOF is wrapped is another error type.
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return err == io.EOF || err.Error() == "EOF"
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}
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// start - starts separate goroutine for each TCP listener. A valid new connection is passed to httpListener.acceptCh.
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func (listener *httpListener) start() {
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listener.acceptCh = make(chan acceptResult)
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listener.doneCh = make(chan struct{})
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// Closure to send acceptResult to acceptCh.
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// It returns true if the result is sent else false if returns when doneCh is closed.
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send := func(result acceptResult, doneCh <-chan struct{}) bool {
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select {
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case listener.acceptCh <- result:
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// Successfully written to acceptCh
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return true
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case <-doneCh:
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// As stop signal is received, close accepted connection.
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if result.conn != nil {
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result.conn.Close()
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}
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return false
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}
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}
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// Closure to handle single connection.
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handleConn := func(tcpConn *net.TCPConn, doneCh <-chan struct{}) {
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rawConn, err := tcpConn.SyscallConn()
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if err == nil {
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setTCPParameters(rawConn)
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}
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send(acceptResult{tcpConn, nil}, doneCh)
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}
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// Closure to handle TCPListener until done channel is closed.
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handleListener := func(tcpListener *net.TCPListener, doneCh <-chan struct{}) {
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for {
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tcpConn, err := tcpListener.AcceptTCP()
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if err != nil {
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// Returns when send fails.
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if !send(acceptResult{nil, err}, doneCh) {
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return
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}
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} else {
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go handleConn(tcpConn, doneCh)
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}
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}
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}
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// Start separate goroutine for each TCP listener to handle connection.
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for _, tcpListener := range listener.tcpListeners {
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go handleListener(tcpListener, listener.doneCh)
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}
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}
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// Accept - reads from httpListener.acceptCh for one of previously accepted TCP connection and returns the same.
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func (listener *httpListener) Accept() (conn net.Conn, err error) {
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result, ok := <-listener.acceptCh
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if ok {
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return result.conn, result.err
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}
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return nil, syscall.EINVAL
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}
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// Close - closes underneath all TCP listeners.
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func (listener *httpListener) Close() (err error) {
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listener.mutex.Lock()
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defer listener.mutex.Unlock()
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if listener.doneCh == nil {
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return syscall.EINVAL
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}
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for i := range listener.tcpListeners {
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listener.tcpListeners[i].Close()
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}
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close(listener.doneCh)
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listener.doneCh = nil
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return nil
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}
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// Addr - net.Listener interface compatible method returns net.Addr. In case of multiple TCP listeners, it returns '0.0.0.0' as IP address.
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func (listener *httpListener) Addr() (addr net.Addr) {
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addr = listener.tcpListeners[0].Addr()
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if len(listener.tcpListeners) == 1 {
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return addr
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}
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tcpAddr := addr.(*net.TCPAddr)
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if ip := net.ParseIP("0.0.0.0"); ip != nil {
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tcpAddr.IP = ip
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}
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addr = tcpAddr
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return addr
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}
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// Addrs - returns all address information of TCP listeners.
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func (listener *httpListener) Addrs() (addrs []net.Addr) {
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for i := range listener.tcpListeners {
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addrs = append(addrs, listener.tcpListeners[i].Addr())
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}
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return addrs
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}
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// newHTTPListener - creates new httpListener object which is interface compatible to net.Listener.
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// httpListener is capable to
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// * listen to multiple addresses
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// * controls incoming connections only doing HTTP protocol
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func newHTTPListener(serverAddrs []string) (listener *httpListener, err error) {
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var tcpListeners []*net.TCPListener
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// Close all opened listeners on error
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defer func() {
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if err == nil {
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return
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}
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for _, tcpListener := range tcpListeners {
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// Ignore error on close.
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tcpListener.Close()
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}
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}()
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for _, serverAddr := range serverAddrs {
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var l net.Listener
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if l, err = listen("tcp", serverAddr); err != nil {
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if l, err = fallbackListen("tcp", serverAddr); err != nil {
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return nil, err
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}
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}
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tcpListener, ok := l.(*net.TCPListener)
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if !ok {
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return nil, fmt.Errorf("unexpected listener type found %v, expected net.TCPListener", l)
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}
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tcpListeners = append(tcpListeners, tcpListener)
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}
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listener = &httpListener{
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tcpListeners: tcpListeners,
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}
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listener.start()
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return listener, nil
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}
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