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tcp.go
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tcp.go
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/*
Copyright 2017 The Kubernetes Authors.
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.
*/
package controller
import (
"fmt"
"io"
"net"
"github.com/golang/glog"
"github.com/paultag/sniff/parser"
)
// TCPServer describes a server that works in passthrough mode.
type TCPServer struct {
Hostname string
IP string
Port int
ProxyProtocol bool
}
// TCPProxy describes the passthrough servers and a default as catch all.
type TCPProxy struct {
ServerList []*TCPServer
Default *TCPServer
}
// Get returns the TCPServer to use for a given host.
func (p *TCPProxy) Get(host string) *TCPServer {
if p.ServerList == nil {
return p.Default
}
for _, s := range p.ServerList {
if s.Hostname == host {
return s
}
}
return p.Default
}
// Handle reads enough information from the connection to extract the hostname
// and open a connection to the passthrough server.
func (p *TCPProxy) Handle(conn net.Conn) {
defer conn.Close()
data := make([]byte, 4096)
length, err := conn.Read(data)
if err != nil {
glog.V(4).Infof("Error reading the first 4k of the connection: %s", err)
return
}
proxy := p.Default
hostname, err := parser.GetHostname(data[:])
if err == nil {
glog.V(4).Infof("Parsed hostname from TLS Client Hello: %s", hostname)
proxy = p.Get(hostname)
}
if proxy == nil {
glog.V(4).Infof("There is no configured proxy for SSL connections.")
return
}
clientConn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", proxy.IP, proxy.Port))
if err != nil {
return
}
defer clientConn.Close()
if proxy.ProxyProtocol {
// write out the Proxy Protocol header
localAddr := conn.LocalAddr().(*net.TCPAddr)
remoteAddr := conn.RemoteAddr().(*net.TCPAddr)
protocol := "UNKNOWN"
if remoteAddr.IP.To4() != nil {
protocol = "TCP4"
} else if remoteAddr.IP.To16() != nil {
protocol = "TCP6"
}
proxyProtocolHeader := fmt.Sprintf("PROXY %s %s %s %d %d\r\n", protocol, remoteAddr.IP.String(), localAddr.IP.String(), remoteAddr.Port, localAddr.Port)
glog.V(4).Infof("Writing Proxy Protocol header: %s", proxyProtocolHeader)
_, err = fmt.Fprintf(clientConn, proxyProtocolHeader)
}
if err != nil {
glog.Errorf("Error writing Proxy Protocol header: %s", err)
clientConn.Close()
} else {
_, err = clientConn.Write(data[:length])
if err != nil {
glog.Errorf("Error writing the first 4k of proxy data: %s", err)
clientConn.Close()
}
}
pipe(clientConn, conn)
}
func pipe(client, server net.Conn) {
doCopy := func(s, c net.Conn, cancel chan<- bool) {
io.Copy(s, c)
cancel <- true
}
cancel := make(chan bool, 2)
go doCopy(server, client, cancel)
go doCopy(client, server, cancel)
select {
case <-cancel:
return
}
}