builder/amazon: guard aginst empty/nil PrivateIpAddress and updated tests.

builder/amazon/common/ssh.go

@@ -34,7 +34,7 @@ func SSHHost(e ec2Describer, private bool) func(multistep.StateBag) (string, err
 				} else if i.PrivateIpAddress != nil && *i.PrivateIpAddress != "" {
 					host = *i.PrivateIpAddress
 				}
-			} else if private {
+			} else if private && i.PrivateIpAddress != nil && *i.PrivateIpAddress != "" {
 				host = *i.PrivateIpAddress
 			} else if i.PublicDnsName != nil && *i.PublicDnsName != "" {
 				host = *i.PublicDnsName

builder/amazon/common/ssh_test.go

@@ -28,15 +28,15 @@ func TestSSHHost(t *testing.T) {
 		wantHost string
 	}{
 		{1, "", false, true, publicDNS},
-		{1, "", true, true, publicDNS},
+		{1, "", true, true, privateIP},
 		{1, "vpc-id", false, true, publicIP},
 		{1, "vpc-id", true, true, privateIP},
 		{2, "", false, true, publicDNS},
-		{2, "", true, true, publicDNS},
+		{2, "", true, true, privateIP},
 		{2, "vpc-id", false, true, publicIP},
 		{2, "vpc-id", true, true, privateIP},
-		{3, "", false, false, ""},
-		{3, "", true, false, ""},
+		{2, "", false, true, publicDNS},
+		{2, "", true, true, privateIP},
 		{3, "vpc-id", false, false, ""},
 		{3, "vpc-id", true, false, ""},
 	}