From 422f294129f2beb7c2a89ae3dad7a68b6b165e73 Mon Sep 17 00:00:00 2001
From: Zhongcheng Lao <Zhongcheng.Lao@microsoft.com>
Date: Thu, 14 Nov 2019 21:08:11 +0800
Subject: [PATCH] Prefer IPv4 over v6 and global unicast IP by default in
 Hyper-V driver

Signed-off-by: Zhongcheng Lao <Zhongcheng.Lao@microsoft.com>
---
 drivers/hyperv/hyperv.go | 41 +++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff --git a/drivers/hyperv/hyperv.go b/drivers/hyperv/hyperv.go
index 70e840fc06..be8dc2e04f 100644
--- a/drivers/hyperv/hyperv.go
+++ b/drivers/hyperv/hyperv.go
@@ -18,7 +18,7 @@ import (
 )
 
 const (
-	DefaultProtocol = iota
+	Default = iota
 	PreferIPv4
 	PreferIPv6
 )
@@ -58,7 +58,7 @@ func NewDriver(hostName, storePath string) *Driver {
 		MemSize:                  defaultMemory,
 		CPU:                      defaultCPU,
 		DisableDynamicMemory:     defaultDisableDynamicMemory,
-		PreferredNetworkProtocol: DefaultProtocol,
+		PreferredNetworkProtocol: Default,
 		WaitTimeoutInSeconds:     defaultWaitTimeoutInSeconds,
 	}
 }
@@ -464,7 +464,7 @@ func (d *Driver) Kill() error {
 }
 
 func isIPv4(address string) bool {
-	return strings.Count(address, ":") < 2
+	return strings.Count(address, ":") < 1
 }
 
 func (d *Driver) GetIP() (string, error) {
@@ -486,20 +486,33 @@ func (d *Driver) GetIP() (string, error) {
 		return "", fmt.Errorf("IP not found")
 	}
 
+	var preferredIP string
 	switch d.PreferredNetworkProtocol {
 	case PreferIPv4:
 		for _, ipStr := range resp {
 			ip := net.ParseIP(ipStr)
-			if isIPv4(ipStr) && ip.To4() != nil && ip.IsGlobalUnicast() {
-				return ipStr, nil
+			if isIPv4(ipStr) && ip.To4() != nil {
+				if preferredIP == "" {
+					preferredIP = ipStr
+				}
+				if ip.IsGlobalUnicast() {
+					preferredIP = ipStr
+					break
+				}
 			}
 		}
 
 	case PreferIPv6:
 		for _, ipStr := range resp {
 			ip := net.ParseIP(ipStr)
-			if !isIPv4(ipStr) && ip.IsGlobalUnicast() {
-				return ipStr, nil
+			if !isIPv4(ipStr) {
+				if preferredIP == "" {
+					preferredIP = ipStr
+				}
+				if ip.IsGlobalUnicast() {
+					preferredIP = ipStr
+					break
+				}
 			}
 		}
 
@@ -507,12 +520,22 @@ func (d *Driver) GetIP() (string, error) {
 		for _, ipStr := range resp {
 			ip := net.ParseIP(ipStr)
 			if ip.IsGlobalUnicast() {
-				return ipStr, nil
+				if preferredIP == "" {
+					preferredIP = ipStr
+				}
+				if isIPv4(ipStr) && ip.To4() != nil {
+					preferredIP = ipStr
+					break
+				}
 			}
 		}
+
+		if preferredIP == "" {
+			preferredIP = resp[0]
+		}
 	}
 
-	return "", nil
+	return preferredIP, nil
 }
 
 func (d *Driver) publicSSHKeyPath() string {