75 lines
2.1 KiB
Go
75 lines
2.1 KiB
Go
package dhcp
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import (
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"fmt"
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"net"
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"os"
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"path/filepath"
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"strings"
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"git.g3e.fr/syonad/two/internal/metadata"
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)
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func GenerateConfig(c Config) (string, map[string]string, error) {
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if c.InterfaceIP == nil {
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return "", nil, fmt.Errorf("interface ip is required: guests would have no route to the metadata server")
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}
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mask := fmt.Sprintf("%d.%d.%d.%d", c.Network.Mask[0], c.Network.Mask[1], c.Network.Mask[2], c.Network.Mask[3])
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var sb strings.Builder
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fmt.Fprintf(&sb, "no-resolv\n")
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fmt.Fprintf(&sb, "dhcp-range=%s,static,%s,12h\n", c.Network.IP.String(), mask)
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fmt.Fprintf(&sb, "dhcp-option=121,%s\n", strings.Join(classlessRoutes(c), ","))
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if c.DefaultGateway != nil {
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fmt.Fprintf(&sb, "dhcp-option=3,%s\n", c.DefaultGateway.String())
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} else {
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fmt.Fprintf(&sb, "dhcp-option=3\n")
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}
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fmt.Fprintf(&sb, "dhcp-option=6,1.1.1.1,8.8.8.8\n")
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fmt.Fprintf(&sb, "dhcp-hostsdir=%s\n", HostsDir(c.ConfDir, c.Name))
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fmt.Fprintf(&sb, "dhcp-optsdir=%s\n", OptsDir(c.ConfDir, c.Name))
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entries := make(map[string]string)
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i := 0
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for ip := cloneIP(c.Network.IP); c.Network.Contains(ip); incrementIP(ip) {
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entries[ip.String()] = fmt.Sprintf("00:22:33:%02X:%02X:%02X", (i>>16)&0xFF, (i>>8)&0xFF, i&0xFF)
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i++
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}
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for _, dir := range []string{c.ConfDir, HostsDir(c.ConfDir, c.Name), OptsDir(c.ConfDir, c.Name)} {
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if err := os.MkdirAll(dir, 0755); err != nil {
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return "", nil, fmt.Errorf("create %s: %w", dir, err)
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}
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}
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outPath := filepath.Join(c.ConfDir, c.Name+".conf")
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return outPath, entries, os.WriteFile(outPath, []byte(sb.String()), 0644)
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}
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func classlessRoutes(c Config) []string {
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nextHop := c.InterfaceIP.String()
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routes := []string{metadata.ServiceIP + "/32," + nextHop}
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if c.VPCRoute != nil {
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routes = append(routes, c.VPCRoute.String()+","+nextHop)
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}
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if c.DefaultGateway != nil {
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routes = append(routes, "0.0.0.0/0,"+c.DefaultGateway.String())
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}
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return routes
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}
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func incrementIP(ip net.IP) {
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for j := len(ip) - 1; j >= 0; j-- {
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ip[j]++
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if ip[j] != 0 {
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break
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}
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}
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}
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func cloneIP(ip net.IP) net.IP {
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clone := make(net.IP, len(ip))
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copy(clone, ip)
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return clone
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}
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