vendor: add github.com/goftp/server

vendor/github.com/goftp/server/socket.go

@@ -0,0 +1,245 @@
+// Copyright 2018 The goftp Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package server
+
+import (
+	"crypto/tls"
+	"io"
+	"net"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+)
+
+// DataSocket describes a data socket is used to send non-control data between the client and
+// server.
+type DataSocket interface {
+	Host() string
+
+	Port() int
+
+	// the standard io.Reader interface
+	Read(p []byte) (n int, err error)
+
+	// the standard io.ReaderFrom interface
+	ReadFrom(r io.Reader) (int64, error)
+
+	// the standard io.Writer interface
+	Write(p []byte) (n int, err error)
+
+	// the standard io.Closer interface
+	Close() error
+}
+
+type ftpActiveSocket struct {
+	conn   *net.TCPConn
+	host   string
+	port   int
+	logger Logger
+}
+
+func newActiveSocket(remote string, port int, logger Logger, sessionID string) (DataSocket, error) {
+	connectTo := net.JoinHostPort(remote, strconv.Itoa(port))
+
+	logger.Print(sessionID, "Opening active data connection to "+connectTo)
+
+	raddr, err := net.ResolveTCPAddr("tcp", connectTo)
+
+	if err != nil {
+		logger.Print(sessionID, err)
+		return nil, err
+	}
+
+	tcpConn, err := net.DialTCP("tcp", nil, raddr)
+
+	if err != nil {
+		logger.Print(sessionID, err)
+		return nil, err
+	}
+
+	socket := new(ftpActiveSocket)
+	socket.conn = tcpConn
+	socket.host = remote
+	socket.port = port
+	socket.logger = logger
+
+	return socket, nil
+}
+
+func (socket *ftpActiveSocket) Host() string {
+	return socket.host
+}
+
+func (socket *ftpActiveSocket) Port() int {
+	return socket.port
+}
+
+func (socket *ftpActiveSocket) Read(p []byte) (n int, err error) {
+	return socket.conn.Read(p)
+}
+
+func (socket *ftpActiveSocket) ReadFrom(r io.Reader) (int64, error) {
+	return socket.conn.ReadFrom(r)
+}
+
+func (socket *ftpActiveSocket) Write(p []byte) (n int, err error) {
+	return socket.conn.Write(p)
+}
+
+func (socket *ftpActiveSocket) Close() error {
+	return socket.conn.Close()
+}
+
+type ftpPassiveSocket struct {
+	conn      net.Conn
+	port      int
+	host      string
+	ingress   chan []byte
+	egress    chan []byte
+	logger    Logger
+	lock      sync.Mutex // protects conn and err
+	err       error
+	tlsConfig *tls.Config
+}
+
+// Detect if an error is "bind: address already in use"
+//
+// Originally from https://stackoverflow.com/a/52152912/164234
+func isErrorAddressAlreadyInUse(err error) bool {
+	errOpError, ok := err.(*net.OpError)
+	if !ok {
+		return false
+	}
+	errSyscallError, ok := errOpError.Err.(*os.SyscallError)
+	if !ok {
+		return false
+	}
+	errErrno, ok := errSyscallError.Err.(syscall.Errno)
+	if !ok {
+		return false
+	}
+	if errErrno == syscall.EADDRINUSE {
+		return true
+	}
+	const WSAEADDRINUSE = 10048
+	if runtime.GOOS == "windows" && errErrno == WSAEADDRINUSE {
+		return true
+	}
+	return false
+}
+
+func newPassiveSocket(host string, port func() int, logger Logger, sessionID string, tlsConfig *tls.Config) (DataSocket, error) {
+	socket := new(ftpPassiveSocket)
+	socket.ingress = make(chan []byte)
+	socket.egress = make(chan []byte)
+	socket.logger = logger
+	socket.host = host
+	socket.tlsConfig = tlsConfig
+	const retries = 10
+	var err error
+	for i := 1; i <= retries; i++ {
+		socket.port = port()
+		err = socket.GoListenAndServe(sessionID)
+		if err != nil && socket.port != 0 && isErrorAddressAlreadyInUse(err) {
+			// choose a different port on error already in use
+			continue
+		}
+		break
+	}
+	return socket, err
+}
+
+func (socket *ftpPassiveSocket) Host() string {
+	return socket.host
+}
+
+func (socket *ftpPassiveSocket) Port() int {
+	return socket.port
+}
+
+func (socket *ftpPassiveSocket) Read(p []byte) (n int, err error) {
+	socket.lock.Lock()
+	defer socket.lock.Unlock()
+	if socket.err != nil {
+		return 0, socket.err
+	}
+	return socket.conn.Read(p)
+}
+
+func (socket *ftpPassiveSocket) ReadFrom(r io.Reader) (int64, error) {
+	socket.lock.Lock()
+	defer socket.lock.Unlock()
+	if socket.err != nil {
+		return 0, socket.err
+	}
+
+	// For normal TCPConn, this will use sendfile syscall; if not,
+	// it will just downgrade to normal read/write procedure
+	return io.Copy(socket.conn, r)
+}
+
+func (socket *ftpPassiveSocket) Write(p []byte) (n int, err error) {
+	socket.lock.Lock()
+	defer socket.lock.Unlock()
+	if socket.err != nil {
+		return 0, socket.err
+	}
+	return socket.conn.Write(p)
+}
+
+func (socket *ftpPassiveSocket) Close() error {
+	socket.lock.Lock()
+	defer socket.lock.Unlock()
+	if socket.conn != nil {
+		return socket.conn.Close()
+	}
+	return nil
+}
+
+func (socket *ftpPassiveSocket) GoListenAndServe(sessionID string) (err error) {
+	laddr, err := net.ResolveTCPAddr("tcp", net.JoinHostPort("", strconv.Itoa(socket.port)))
+	if err != nil {
+		socket.logger.Print(sessionID, err)
+		return
+	}
+
+	var listener net.Listener
+	listener, err = net.ListenTCP("tcp", laddr)
+	if err != nil {
+		socket.logger.Print(sessionID, err)
+		return
+	}
+
+	add := listener.Addr()
+	parts := strings.Split(add.String(), ":")
+	port, err := strconv.Atoi(parts[len(parts)-1])
+	if err != nil {
+		socket.logger.Print(sessionID, err)
+		return
+	}
+
+	socket.port = port
+	if socket.tlsConfig != nil {
+		listener = tls.NewListener(listener, socket.tlsConfig)
+	}
+
+	socket.lock.Lock()
+	go func() {
+		defer socket.lock.Unlock()
+
+		conn, err := listener.Accept()
+		if err != nil {
+			socket.err = err
+			return
+		}
+		socket.err = nil
+		socket.conn = conn
+		_ = listener.Close()
+	}()
+	return nil
+}