f-34: route: fix missing route for metadata #34

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

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\n", strings.Join(classlessRoutes(c), ","))
-		fmt.Fprintf(&sb, "dhcp-option=121,%s,%s\n", c.VPCRoute.String(), c.VPCGateway.String())
-	}
 	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)
+	InterfaceIP    net.IP     // subnet gateway; next-hop for the metadata and VPC routes
-	VPCRoute       *net.IPNet // if non-nil, emit dhcp-option=121,VPCRoute,VPCGateway
+	VPCRoute       *net.IPNet // if non-nil, routed via InterfaceIP in option 121
-	DefaultGateway net.IP     // if non-nil, emit dhcp-option=3,DefaultGateway; if nil, emit a bare dhcp-option=3 to suppress the dnsmasq default
+	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 +1,7 @@
 package metadata
 
+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 {