forked from google/seesaw
/
dial.go
214 lines (186 loc) · 5.31 KB
/
dial.go
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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Author: jsing@google.com (Joel Sing)
package healthcheck
// This file contains helper routines for dialing connections.
import (
"errors"
"fmt"
"net"
"os"
"strconv"
"syscall"
"time"
)
type conn struct {
fd int
f *os.File
net.Conn
}
func (c *conn) Close() error {
if c.Conn != nil {
c.Conn.Close()
}
if c.f != nil {
err := c.f.Close()
c.fd, c.f = -1, nil
return err
}
if c.fd != -1 {
err := syscall.Close(c.fd)
c.fd = -1
return err
}
return nil
}
func sockaddrToString(sa syscall.Sockaddr) string {
switch sa := sa.(type) {
case *syscall.SockaddrInet4:
return net.JoinHostPort(net.IP(sa.Addr[:]).String(), strconv.Itoa(sa.Port))
case *syscall.SockaddrInet6:
return net.JoinHostPort(net.IP(sa.Addr[:]).String(), strconv.Itoa(sa.Port))
default:
return fmt.Sprintf("(unknown - %T)", sa)
}
}
// dialTCP dials a TCP connection to the specified host and sets marking on the
// socket. The host must be given as an IP address. A mark of zero results in a
// normal (non-marked) connection.
func dialTCP(network, addr string, timeout time.Duration, mark int) (nc net.Conn, err error) {
host, port, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
ip := net.ParseIP(host)
if ip == nil {
return nil, fmt.Errorf("invalid IP address %q", host)
}
p, err := strconv.ParseUint(port, 10, 16)
if err != nil {
return nil, fmt.Errorf("invalid port number %q", port)
}
var domain int
var rsa syscall.Sockaddr
switch network {
case "tcp4":
domain = syscall.AF_INET
if ip.To4() == nil {
return nil, fmt.Errorf("invalid IPv4 address %q", host)
}
sa := &syscall.SockaddrInet4{Port: int(p)}
copy(sa.Addr[:], ip.To4())
rsa = sa
case "tcp6":
domain = syscall.AF_INET6
if ip.To4() != nil {
return nil, fmt.Errorf("invalid IPv6 address %q", host)
}
sa := &syscall.SockaddrInet6{Port: int(p)}
copy(sa.Addr[:], ip.To16())
rsa = sa
default:
return nil, fmt.Errorf("unsupported network %q", network)
}
c := &conn{}
defer func() {
if err != nil {
c.Close()
}
}()
c.fd, err = syscall.Socket(domain, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0)
if err != nil {
return nil, os.NewSyscallError("socket", err)
}
if mark != 0 {
if err := setSocketMark(c.fd, mark); err != nil {
return nil, err
}
}
if err := setSocketTimeout(c.fd, timeout); err != nil {
return nil, err
}
if err := syscall.Connect(c.fd, rsa); err != nil {
return nil, os.NewSyscallError("connect", err)
}
if err := setSocketTimeout(c.fd, 0); err != nil {
return nil, err
}
lsa, _ := syscall.Getsockname(c.fd)
rsa, _ = syscall.Getpeername(c.fd)
name := fmt.Sprintf("%s %s -> %s", network, sockaddrToString(lsa), sockaddrToString(rsa))
c.f = os.NewFile(uintptr(c.fd), name)
// When we call net.FileConn the socket will be made non-blocking and
// we will get a *net.TCPConn in return. The *os.File needs to be
// closed in addition to the *net.TCPConn when we're done (conn.Close
// takes care of that for us).
if c.Conn, err = net.FileConn(c.f); err != nil {
return nil, err
}
if _, ok := c.Conn.(*net.TCPConn); !ok {
return nil, fmt.Errorf("%T is not a *net.TCPConn", c.Conn)
}
return c, nil
}
// dialUDP dials a UDP connection to the specified host and sets marking on the
// socket. A mark of zero results in a normal (non-marked) connection.
func dialUDP(network, addr string, timeout time.Duration, mark int) (*net.UDPConn, error) {
d := net.Dialer{Timeout: timeout}
conn, err := d.Dial(network, addr)
if err != nil {
return nil, err
}
udpConn, ok := conn.(*net.UDPConn)
if !ok {
conn.Close()
return nil, errors.New("dial did not return a *net.UDPConn")
}
if mark == 0 {
return udpConn, nil
}
f, err := udpConn.File()
if err != nil {
udpConn.Close()
return nil, err
}
defer f.Close()
fd := int(f.Fd())
// Calling File results in the socket being set to blocking mode.
// We need to undo this.
if err := syscall.SetNonblock(fd, true); err != nil {
udpConn.Close()
return nil, err
}
if err := setSocketMark(fd, mark); err != nil {
udpConn.Close()
return nil, err
}
return udpConn, nil
}
// setSocketMark sets packet marking on the given socket.
func setSocketMark(fd, mark int) error {
if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_MARK, mark); err != nil {
return os.NewSyscallError("failed to set mark", err)
}
return nil
}
// setSocketTimeout sets the receive and send timeouts on the given socket.
func setSocketTimeout(fd int, timeout time.Duration) error {
tv := syscall.NsecToTimeval(timeout.Nanoseconds())
for _, opt := range []int{syscall.SO_RCVTIMEO, syscall.SO_SNDTIMEO} {
if err := syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, opt, &tv); err != nil {
return os.NewSyscallError("setsockopt", err)
}
}
return nil
}