From bab0d39d51666142548ec1dc09f1428008c1d4d4 Mon Sep 17 00:00:00 2001
From: Andrii Chubatiuk <andrew.chubatiuk@gmail.com>
Date: Tue, 13 Apr 2021 16:33:33 +0300
Subject: [PATCH] support multiple host network aliases for the same interface

---
 client/fingerprint/network.go      | 36 +++++++++++++---------
 client/fingerprint/network_test.go | 49 ++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 15 deletions(-)

diff --git a/client/fingerprint/network.go b/client/fingerprint/network.go
index 1c77a7657b3..b36a5482684 100644
--- a/client/fingerprint/network.go
+++ b/client/fingerprint/network.go
@@ -168,17 +168,19 @@ func (f *NetworkFingerprint) createNodeNetworkResources(ifaces []net.Interface,
 			} else {
 				family = structs.NodeNetworkAF_IPv6
 			}
-			newAddr := structs.NodeNetworkAddress{
-				Address: ip.String(),
-				Family:  family,
-				Alias:   deriveAddressAlias(iface, ip, conf),
-			}
+			for _, alias := range deriveAddressAliases(iface, ip, conf) {
+				newAddr := structs.NodeNetworkAddress{
+					Address: ip.String(),
+					Family:  family,
+					Alias:   alias,
+				}
 
-			if newAddr.Alias != "" {
-				if ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
-					linkLocalAddrs = append(linkLocalAddrs, newAddr)
-				} else {
-					networkAddrs = append(networkAddrs, newAddr)
+				if newAddr.Alias != "" {
+					if ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
+						linkLocalAddrs = append(linkLocalAddrs, newAddr)
+					} else {
+						networkAddrs = append(networkAddrs, newAddr)
+					}
 				}
 			}
 		}
@@ -200,7 +202,7 @@ func (f *NetworkFingerprint) createNodeNetworkResources(ifaces []net.Interface,
 	return nets, nil
 }
 
-func deriveAddressAlias(iface net.Interface, addr net.IP, config *config.Config) string {
+func deriveAddressAliases(iface net.Interface, addr net.IP, config *config.Config) (aliases []string) {
 	for name, conf := range config.HostNetworks {
 		var cidrMatch, ifaceMatch bool
 		if conf.CIDR != "" {
@@ -231,22 +233,26 @@ func deriveAddressAlias(iface net.Interface, addr net.IP, config *config.Config)
 			ifaceMatch = true
 		}
 		if cidrMatch && ifaceMatch {
-			return name
+			aliases = append(aliases, name)
 		}
 	}
 
+	if len(aliases) > 0 {
+		return
+	}
+
 	if config.NetworkInterface != "" {
 		if config.NetworkInterface == iface.Name {
-			return "default"
+			return []string{"default"}
 		}
 	} else if ri, err := sockaddr.NewRouteInfo(); err == nil {
 		defaultIface, err := ri.GetDefaultInterfaceName()
 		if err == nil && iface.Name == defaultIface {
-			return "default"
+			return []string{"default"}
 		}
 	}
 
-	return ""
+	return
 }
 
 // createNetworkResources creates network resources for every IP
diff --git a/client/fingerprint/network_test.go b/client/fingerprint/network_test.go
index 5b55b87a690..4b0fce93dcc 100644
--- a/client/fingerprint/network_test.go
+++ b/client/fingerprint/network_test.go
@@ -4,11 +4,13 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"sort"
 	"testing"
 
 	"github.com/hashicorp/nomad/client/config"
 	"github.com/hashicorp/nomad/helper/testlog"
 	"github.com/hashicorp/nomad/nomad/structs"
+	"github.com/stretchr/testify/require"
 )
 
 // Set skipOnlineTestEnvVar to a non-empty value to skip network tests.  Useful
@@ -437,3 +439,50 @@ func TestNetworkFingerPrint_LinkLocal_Disallowed(t *testing.T) {
 		t.Fatalf("should not apply attributes")
 	}
 }
+
+func TestNetworkFingerPrint_MultipleAliases(t *testing.T) {
+	f := &NetworkFingerprint{logger: testlog.HCLogger(t), interfaceDetector: &NetworkInterfaceDetectorMultipleInterfaces{}}
+	node := &structs.Node{
+		Attributes: make(map[string]string),
+	}
+	cfg := &config.Config{
+		NetworkSpeed:     100,
+		NetworkInterface: "eth3",
+		HostNetworks: map[string]*structs.ClientHostNetworkConfig{
+			"alias1": {
+				Name:      "alias1",
+				Interface: "eth3",
+				CIDR:      "169.254.155.20/32",
+			},
+			"alias2": {
+				Name:      "alias2",
+				Interface: "eth3",
+				CIDR:      "169.254.155.20/32",
+			},
+			"alias3": {
+				Name:      "alias3",
+				Interface: "eth0",
+				CIDR:      "100.64.0.11/10",
+			},
+		},
+	}
+
+	request := &FingerprintRequest{Config: cfg, Node: node}
+	var response FingerprintResponse
+	err := f.Fingerprint(request, &response)
+	require.NoError(t, err)
+
+	aliases := []string{}
+	for _, network := range response.NodeResources.NodeNetworks {
+		for _, address := range network.Addresses {
+			aliases = append(aliases, address.Alias)
+		}
+	}
+	expected := []string{}
+	for alias, _ := range cfg.HostNetworks {
+		expected = append(expected, alias)
+	}
+	sort.Strings(expected)
+	sort.Strings(aliases)
+	require.Equal(t, expected, aliases, "host networks should match aliases")
+}