From b7286213d593316cc47f5eebcac64c815db8bad0 Mon Sep 17 00:00:00 2001
From: Daniil Skomarovskiy <0xbad0c0d3@gmail.com>
Date: Thu, 26 Sep 2019 12:13:16 +0300
Subject: [PATCH] --dns-option "resolve-docker-internal" to enable the feature

Signed-off-by: Daniil Skomarovskiy <0xbad0c0d3@gmail.com>
---
 network.go | 17 +++++++++++++++++
 sandbox.go | 27 ++++++++++++++++++---------
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/network.go b/network.go
index f128cac785..bb273c18ee 100644
--- a/network.go
+++ b/network.go
@@ -23,6 +23,14 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+type hostInfoStruct struct {
+	ipV4 net.IP
+	ipV6 net.IP
+}
+
+// HostInfo will be used to resolve host.docker.internal hostname to an address
+var HostInfo *hostInfoStruct
+
 // A Network represents a logical connectivity zone that containers may
 // join using the Link method. A Network is managed by a specific driver.
 type Network interface {
@@ -802,6 +810,15 @@ func NetworkOptionScope(scope string) NetworkOption {
 
 // NetworkOptionIpam function returns an option setter for the ipam configuration for this network
 func NetworkOptionIpam(ipamDriver string, addrSpace string, ipV4 []*IpamConf, ipV6 []*IpamConf, opts map[string]string) NetworkOption {
+	if ipamDriver == "default" && HostInfo == nil {
+		HostInfo = &hostInfoStruct{}
+		if len(ipV4) > 0 {
+			HostInfo.ipV4 = net.ParseIP(ipV4[0].Gateway)
+		}
+		if len(ipV6) > 0 {
+			HostInfo.ipV6 = net.ParseIP(ipV6[0].Gateway)
+		}
+	}
 	return func(n *network) {
 		if ipamDriver != "" {
 			n.ipamType = ipamDriver
diff --git a/sandbox.go b/sandbox.go
index 8c104667b3..87640becf1 100644
--- a/sandbox.go
+++ b/sandbox.go
@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"net"
-	"runtime"
 	"sort"
 	"strings"
 	"sync"
@@ -134,9 +133,10 @@ type containerConfig struct {
 }
 
 const (
-	resolverIPSandbox     = "127.0.0.11"
-	hostDockerInternal    = "host.docker.internal"
-	gatewayDockerInternal = "gateway.docker.internal"
+	resolverIPSandbox           = "127.0.0.11"
+	dnsOptResolveDockerInternal = "resolve-docker-internal"
+	hostDockerInternal          = "host.docker.internal"
+	gatewayDockerInternal       = "gateway.docker.internal"
 )
 
 func (sb *sandbox) ID() string {
@@ -404,6 +404,15 @@ func (sb *sandbox) getEndpoint(id string) *endpoint {
 	return nil
 }
 
+func (sb *sandbox) shouldResolveInternal() bool {
+	for _, opt := range sb.config.dnsOptionsList {
+		if opt == dnsOptResolveDockerInternal {
+			return true
+		}
+	}
+	return false
+}
+
 func (sb *sandbox) updateGateway(ep *endpoint) error {
 	sb.Lock()
 	osSbox := sb.osSbox
@@ -430,11 +439,6 @@ func (sb *sandbox) updateGateway(ep *endpoint) error {
 		return fmt.Errorf("failed to set IPv6 gateway while updating gateway: %v", err)
 	}
 
-	if ep.needResolver() && runtime.GOOS == "linux" {
-		ep.network.addSvcRecords(ep.ID(), hostDockerInternal, ep.svcID, ep.Gateway(), ep.GatewayIPv6(), true, "updateGateway")
-		ep.network.addSvcRecords(ep.ID(), gatewayDockerInternal, ep.svcID, ep.Gateway(), ep.GatewayIPv6(), true, "updateGateway")
-	}
-
 	return nil
 }
 
@@ -711,6 +715,11 @@ func (sb *sandbox) EnableService() (err error) {
 				return fmt.Errorf("could not update state for endpoint %s into cluster: %v", ep.Name(), err)
 			}
 			ep.enableService()
+			if ep.needResolver() && sb.shouldResolveInternal() {
+				ep.network.addSvcRecords(ep.ID(), hostDockerInternal, ep.svcID, HostInfo.ipV4, HostInfo.ipV6, true, "updateGateway")
+				ep.network.addSvcRecords(ep.ID(), gatewayDockerInternal, ep.svcID, HostInfo.ipV4, HostInfo.ipV6, true, "updateGateway")
+			}
+
 		}
 	}
 	logrus.Debugf("EnableService %s DONE", sb.containerID)