f-34: route: add test for route metadata #34

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

internal/dhcp/dhcp_test.go

@@ -55,7 +55,7 @@ func newConf(t *testing.T, cidr string) Config {
 	gw := net.ParseIP("192.168.1.1").To4()
 	return Config{
 		Network:        network,
-		VPCGateway:     gw,
+		InterfaceIP:    net.ParseIP("192.168.1.254").To4(),
 		VPCRoute:       vpcNet,
 		DefaultGateway: gw,
 		Name:           "test",
@@ -136,23 +136,19 @@ func TestGenerateConfig_VxlanEmitsNoRouterOption(t *testing.T) {
 }
 
 func TestGenerateConfig_ContainsVPCRoute(t *testing.T) {
-	conf := newConf(t, "192.168.1.0/29")
-	path, _, _ := GenerateConfig(conf)
-	content, _ := os.ReadFile(path)
-
-	if !strings.Contains(string(content), "dhcp-option=121,10.0.0.0/16,192.168.1.1") {
-		t.Errorf("dhcp-option=121 absente ou incorrecte :\n%s", content)
+	routes := route121(t, confLines(t, newConf(t, "192.168.1.0/29")))
+	if !strings.Contains(routes, "10.0.0.0/16,192.168.1.254") {
+		t.Errorf("route VPC absente, ou next-hop autre que l'interface_ip du subnet :\n%s", routes)
 	}
 }
 
 func TestGenerateConfig_NoVPCRoute(t *testing.T) {
 	conf := newConf(t, "192.168.1.0/29")
 	conf.VPCRoute = nil
-	path, _, _ := GenerateConfig(conf)
-	content, _ := os.ReadFile(path)
 
-	if strings.Contains(string(content), "dhcp-option=121,") {
-		t.Errorf("dhcp-option=121 présente alors que VPCRoute=nil :\n%s", content)
+	routes := route121(t, confLines(t, conf))
+	if strings.Contains(routes, "10.0.0.0/16") {
+		t.Errorf("route VPC présente alors que VPCRoute=nil :\n%s", routes)
 	}
 }
 
@@ -160,6 +156,7 @@ func TestGenerateConfig_ContainsDhcpRange(t *testing.T) {
 	_, network, _ := net.ParseCIDR("10.10.0.0/24")
 	conf := Config{
 		Network:     network,
+		InterfaceIP: net.ParseIP("10.10.0.1").To4(),
 		Name:        "vpc1",
 		ConfDir:     t.TempDir(),
 	}
@@ -205,6 +202,7 @@ func TestGenerateConfig_CreatesConfDir(t *testing.T) {
 	_, network, _ := net.ParseCIDR("10.0.0.0/30")
 	conf := Config{
 		Network:     network,
+		InterfaceIP: net.ParseIP("10.0.0.1").To4(),
 		Name:        "net",
 		ConfDir:     dir,
 	}
@@ -215,3 +213,79 @@ func TestGenerateConfig_CreatesConfDir(t *testing.T) {
 		t.Errorf("répertoire %q non créé", dir)
 	}
 }
+
+// --- option 121 : routes classless ---
+
+func confLines(t *testing.T, c Config) string {
+	t.Helper()
+	path, _, err := GenerateConfig(c)
+	if err != nil {
+		t.Fatalf("GenerateConfig : %v", err)
+	}
+	content, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("lecture : %v", err)
+	}
+	return string(content)
+}
+
+func route121(t *testing.T, content string) string {
+	t.Helper()
+	for _, line := range strings.Split(content, "\n") {
+		if strings.HasPrefix(line, "dhcp-option=121,") {
+			return strings.TrimPrefix(line, "dhcp-option=121,")
+		}
+	}
+	t.Fatalf("aucune dhcp-option=121 dans :\n%s", content)
+	return ""
+}
+
+func TestGenerateConfig_AlwaysRoutesToMetadata(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.VPCRoute = nil
+	conf.DefaultGateway = nil
+
+	routes := route121(t, confLines(t, conf))
+	if !strings.Contains(routes, "169.254.169.254/32,192.168.1.254") {
+		t.Errorf("sans route vers le serveur de métadonnées, cloud-init échoue et la VM n'est pas provisionnée :\n%s", routes)
+	}
+}
+
+func TestGenerateConfig_MetadataRouteEvenInBridgeMode(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.VPCRoute = nil
+
+	routes := route121(t, confLines(t, conf))
+	if !strings.Contains(routes, "169.254.169.254/32") {
+		t.Errorf("le mode bridge a besoin de la même route :\n%s", routes)
+	}
+}
+
+func TestGenerateConfig_DefaultRouteAlsoInOption121(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.VPCRoute = nil
+
+	routes := route121(t, confLines(t, conf))
+	if !strings.Contains(routes, "0.0.0.0/0,192.168.1.1") {
+		t.Errorf("RFC 3442 : un client qui lit l'option 121 ignore l'option 3, la route par défaut doit donc figurer dans la 121 :\n%s", routes)
+	}
+}
+
+func TestGenerateConfig_NoDefaultRouteMeansNoCatchAllInOption121(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.DefaultGateway = nil
+
+	routes := route121(t, confLines(t, conf))
+	if strings.Contains(routes, "0.0.0.0/0") {
+		t.Errorf("aucune route par défaut demandée, la 121 ne doit pas en contenir :\n%s", routes)
+	}
+}
+
+func TestGenerateConfig_MissingInterfaceIPIsAnError(t *testing.T) {
+	conf := newConf(t, "192.168.1.0/29")
+	conf.InterfaceIP = nil
+
+	if _, _, err := GenerateConfig(conf); err == nil {
+		t.Error("sans interface_ip aucune route metadata n'est possible : il faut échouer, pas écrire une conf muette")
+	}
+}

internal/dhcp/generate.go

@@ -6,17 +6,20 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"git.g3e.fr/syonad/two/internal/metadata"
 )
 
 func GenerateConfig(c Config) (string, map[string]string, error) {
+	if c.InterfaceIP == nil {
+		return "", nil, fmt.Errorf("interface ip is required: guests would have no route to the metadata server")
+	}
 	mask := fmt.Sprintf("%d.%d.%d.%d", c.Network.Mask[0], c.Network.Mask[1], c.Network.Mask[2], c.Network.Mask[3])
 
 	var sb strings.Builder
 	fmt.Fprintf(&sb, "no-resolv\n")
 	fmt.Fprintf(&sb, "dhcp-range=%s,static,%s,12h\n", c.Network.IP.String(), mask)
-	if c.VPCRoute != nil {
-		fmt.Fprintf(&sb, "dhcp-option=121,%s,%s\n", c.VPCRoute.String(), c.VPCGateway.String())
-	}
+	fmt.Fprintf(&sb, "dhcp-option=121,%s\n", strings.Join(classlessRoutes(c), ","))
 	if c.DefaultGateway != nil {
 		fmt.Fprintf(&sb, "dhcp-option=3,%s\n", c.DefaultGateway.String())
 	} else {
@@ -40,6 +43,19 @@ func GenerateConfig(c Config) (string, map[string]string, error) {
 	return outPath, entries, os.WriteFile(outPath, []byte(sb.String()), 0644)
 }
 
+func classlessRoutes(c Config) []string {
+	nextHop := c.InterfaceIP.String()
+
+	routes := []string{metadata.ServiceIP + "/32," + nextHop}
+	if c.VPCRoute != nil {
+		routes = append(routes, c.VPCRoute.String()+","+nextHop)
+	}
+	if c.DefaultGateway != nil {
+		routes = append(routes, "0.0.0.0/0,"+c.DefaultGateway.String())
+	}
+	return routes
+}
+
 func incrementIP(ip net.IP) {
 	for j := len(ip) - 1; j >= 0; j-- {
 		ip[j]++

internal/dhcp/struct.go

@@ -8,9 +8,9 @@ const DefaultConfDir = "/etc/dnsmasq.d"
 
 type Config struct {
 	Network        *net.IPNet
-	VPCGateway     net.IP     // next-hop for VPCRoute (option 121)
-	VPCRoute       *net.IPNet // if non-nil, emit dhcp-option=121,VPCRoute,VPCGateway
-	DefaultGateway net.IP     // if non-nil, emit dhcp-option=3,DefaultGateway; if nil, emit a bare dhcp-option=3 to suppress the dnsmasq default
+	InterfaceIP    net.IP     // subnet gateway; next-hop for the metadata and VPC routes
+	VPCRoute       *net.IPNet // if non-nil, routed via InterfaceIP in option 121
+	DefaultGateway net.IP     // if non-nil, default route via option 3 and 0.0.0.0/0 in option 121
 	Name           string
 	ConfDir        string
 }

internal/iptables/iptables.go

@@ -3,6 +3,8 @@ package iptables
 import (
 	"fmt"
 	"os/exec"
+
+	"git.g3e.fr/syonad/two/internal/metadata"
 )
 
 func addRule(args ...string) error {
@@ -16,7 +18,7 @@ func deleteRule(args ...string) error {
 func AddMetadataRedirect(vmIP, gatewayIP, metadataPort string) error {
 	if err := addRule("PREROUTING",
 		"-s", vmIP+"/32",
-		"-d", "169.254.169.254/32",
+		"-d", metadata.ServiceIP+"/32",
 		"-p", "tcp", "-m", "tcp",
 		"--dport", "80",
 		"-j", "DNAT",
@@ -30,7 +32,7 @@ func AddMetadataRedirect(vmIP, gatewayIP, metadataPort string) error {
 func DeleteMetadataRedirect(vmIP, gatewayIP, metadataPort string) error {
 	if err := deleteRule("PREROUTING",
 		"-s", vmIP+"/32",
-		"-d", "169.254.169.254/32",
+		"-d", metadata.ServiceIP+"/32",
 		"-p", "tcp", "-m", "tcp",
 		"--dport", "80",
 		"-j", "DNAT",

internal/metadata/struct.go

@@ -1,5 +1,10 @@
 package metadata
 
+// ServiceIP is the well-known address guests use to reach the metadata server.
+// Traffic to it is DNATed to the subnet gateway by internal/iptables, and the
+// route to it is advertised by internal/dhcp.
+const ServiceIP = "169.254.169.254"
+
 type NoCloudData struct {
 	MetaData      string
 	UserData      string

internal/subnet/create.go

@@ -139,10 +139,10 @@ func startDHCP(db *badger.DB, subnetName string, d subnetData) error {
 		Network:     d.cidr,
 		Name:        d.vpc + "_" + d.bridge,
 		ConfDir:     dhcp.DefaultConfDir,
+		InterfaceIP: d.interfaceIP,
 	}
 	switch d.mode {
 	case "vxlan":
-		conf.VPCGateway = d.interfaceIP
 		conf.VPCRoute = d.vpcCIDR
 	case "bridge":
 		if d.defaultRoute {