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forwarding_proxy.go
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/
forwarding_proxy.go
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package net
import (
"fmt"
"net"
"strconv"
"github.com/carvel-dev/kwt/pkg/kwt/net/dstconn"
"github.com/carvel-dev/kwt/pkg/kwt/net/forwarder"
)
type ForwardingProxy struct {
forwarderFactory forwarder.Factory
dnsServerFactory DNSServerFactory
shutdownCh chan struct{}
logTag string
logger Logger
}
func NewForwardingProxy(forwarderFactory forwarder.Factory, dnsServerFactory DNSServerFactory, logger Logger) *ForwardingProxy {
return &ForwardingProxy{forwarderFactory, dnsServerFactory, make(chan struct{}), "ForwardingProxy", logger}
}
func (o *ForwardingProxy) Serve(dstConnFactory dstconn.Factory, subnets []net.IPNet, dnsIPs []net.IP) error {
origDstResolver, err := o.forwarderFactory.NewOriginalDstResolver()
if err != nil {
return err
}
tcpProxy := NewTCPProxy(origDstResolver, dstConnFactory, o.logger)
tcpProxyErrCh := make(chan error)
tcpProxyStartedCh := make(chan struct{})
udpProxy := NewUDPProxy(dstConnFactory, o.logger)
udpProxyErrCh := make(chan error)
udpProxyStartedCh := make(chan struct{})
dnsServer, err := o.dnsServerFactory.NewDNSServer(dstConnFactory)
if err != nil {
return err
}
dnsServerErrCh := make(chan error)
dnsServerStartedCh := make(chan struct{})
forwarder := forwarder.NewLocking()
forwarderErrCh := make(chan error)
go func() {
tcpProxyErrCh <- tcpProxy.Serve(tcpProxyStartedCh)
}()
go func() {
udpProxyErrCh <- udpProxy.Serve(udpProxyStartedCh)
}()
go func() {
dnsServerErrCh <- dnsServer.Serve(dnsServerStartedCh)
}()
go func() {
<-tcpProxyStartedCh
<-udpProxyStartedCh
<-dnsServerStartedCh
actualForwarder, err := o.buildForwarder(tcpProxy, dnsServer)
if err != nil {
forwarderErrCh <- err
return
}
err = actualForwarder.CheckPrereqs()
if err != nil {
forwarderErrCh <- err
return
}
forwarder.SetForwarder(actualForwarder)
o.logger.Info(o.logTag, "Forwarding subnets: %s", SubnetsAsString(subnets))
err = forwarder.Add(subnets, dnsIPs)
if err != nil {
forwarderErrCh <- err
return
}
o.dnsServerFactory.NewDNSOSCache().Flush()
o.logger.Info(o.logTag, "Ready!")
}()
errCh := make(chan error)
go func() {
select {
case <-o.shutdownCh:
errCh <- nil
case err := <-tcpProxyErrCh:
errCh <- err
case err := <-udpProxyErrCh:
errCh <- err
case err := <-dnsServerErrCh:
errCh <- err
case err := <-forwarderErrCh:
errCh <- err
}
}()
origErr := <-errCh
// Most import to reset since forwarder's resources are not reclaimed automatically
err = forwarder.Reset()
if err != nil {
o.logger.Error(o.logTag, "Failed resetting forwarder: %s", err)
}
err = tcpProxy.Shutdown()
if err != nil {
o.logger.Error(o.logTag, "Failed shutting down TCP proxy: %s", err)
}
err = udpProxy.Shutdown()
if err != nil {
o.logger.Error(o.logTag, "Failed shutting down UDP proxy: %s", err)
}
err = dnsServer.Shutdown()
if err != nil {
o.logger.Error(o.logTag, "Failed shutting down DNS server: %s", err)
}
return origErr
}
func (o *ForwardingProxy) Shutdown() error {
close(o.shutdownCh)
return nil
}
func (o *ForwardingProxy) buildForwarder(tcpProxy *TCPProxy, dnsServer DNSServer) (forwarder.Forwarder, error) {
tcpPort, err := o.portFromAddr(tcpProxy.Addr())
if err != nil {
return nil, err
}
dnsTCPPort, err := o.portFromAddr(dnsServer.TCPAddr())
if err != nil {
return nil, err
}
dnsUDPPort, err := o.portFromAddr(dnsServer.UDPAddr())
if err != nil {
return nil, err
}
return o.forwarderFactory.NewForwarder(forwarder.ForwarderOpts{
DstTCPPort: tcpPort,
DstDNSTCPPort: dnsTCPPort,
DstDNSUDPPort: dnsUDPPort,
})
}
func (*ForwardingProxy) portFromAddr(addr net.Addr) (int, error) {
_, portStr, err := net.SplitHostPort(addr.String())
if err != nil {
return 0, fmt.Errorf("Parsing addr: %s", err)
}
port, err := strconv.Atoi(portStr)
if err != nil {
return 0, fmt.Errorf("Parsing port: %s", err)
}
return port, nil
}