first commit

network/config.go

@@ -0,0 +1,195 @@
+package network
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+)
+
+const ConfigFile = "/etc/network/interfaces"
+
+// InterfaceConfig represents one stanza in /etc/network/interfaces.
+type InterfaceConfig struct {
+	Name    string            `json:"name"`
+	Auto   bool              `json:"auto"`
+	Mode    string            `json:"mode"`              // dhcp, static, loopback, manual
+	Address string            `json:"address,omitempty"` // static only
+	Netmask string            `json:"netmask,omitempty"`
+	Gateway string            `json:"gateway,omitempty"`
+	DNS     []string          `json:"dns,omitempty"`
+	Extra   map[string]string `json:"extra,omitempty"` // other raw options
+}
+
+// --- Pending config store (in-memory, not yet written to disk) ---
+
+var (
+	pendingMu sync.Mutex
+	pending   = map[string]*InterfaceConfig{}
+)
+
+func GetPendingConfig(name string) *InterfaceConfig {
+	pendingMu.Lock()
+	defer pendingMu.Unlock()
+	return pending[name]
+}
+
+func SetPendingConfig(cfg *InterfaceConfig) {
+	pendingMu.Lock()
+	defer pendingMu.Unlock()
+	pending[cfg.Name] = cfg
+}
+
+func ClearPendingConfig(name string) {
+	pendingMu.Lock()
+	defer pendingMu.Unlock()
+	delete(pending, name)
+}
+
+func ClearAllPending() {
+	pendingMu.Lock()
+	defer pendingMu.Unlock()
+	pending = map[string]*InterfaceConfig{}
+}
+
+func GetAllPending() map[string]*InterfaceConfig {
+	pendingMu.Lock()
+	defer pendingMu.Unlock()
+	out := make(map[string]*InterfaceConfig, len(pending))
+	for k, v := range pending {
+		cp := *v
+		out[k] = &cp
+	}
+	return out
+}
+
+// --- Parse /etc/network/interfaces ---
+
+func ParseConfig() (map[string]*InterfaceConfig, error) {
+	f, err := os.Open(ConfigFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return map[string]*InterfaceConfig{}, nil
+		}
+		return nil, fmt.Errorf("open %s: %w", ConfigFile, err)
+	}
+	defer f.Close()
+
+	configs := map[string]*InterfaceConfig{}
+	autoSet := map[string]bool{}
+	var cur *InterfaceConfig
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		// Strip inline comments
+		if idx := strings.Index(line, "#"); idx >= 0 {
+			line = line[:idx]
+		}
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		fields := strings.Fields(line)
+		switch fields[0] {
+		case "auto":
+			for _, n := range fields[1:] {
+				autoSet[n] = true
+			}
+
+		case "iface":
+			// iface <name> <family> <method>
+			if len(fields) < 4 {
+				continue
+			}
+			cur = &InterfaceConfig{
+				Name:  fields[1],
+				Mode:  fields[3],
+				Extra: map[string]string{},
+			}
+			configs[fields[1]] = cur
+
+		default:
+			if cur == nil || len(fields) < 2 {
+				continue
+			}
+			val := strings.Join(fields[1:], " ")
+			switch fields[0] {
+			case "address":
+				cur.Address = val
+			case "netmask":
+				cur.Netmask = val
+			case "gateway":
+				cur.Gateway = val
+			case "dns-nameservers":
+				cur.DNS = fields[1:]
+			default:
+				cur.Extra[fields[0]] = val
+			}
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	for name, cfg := range configs {
+		cfg.Auto = autoSet[name]
+	}
+	return configs, nil
+}
+
+// --- Write /etc/network/interfaces ---
+
+func WriteConfig(configs map[string]*InterfaceConfig) error {
+	// Backup
+	if data, err := os.ReadFile(ConfigFile); err == nil {
+		_ = os.WriteFile(ConfigFile+".bak", data, 0644)
+	}
+
+	f, err := os.Create(ConfigFile)
+	if err != nil {
+		return fmt.Errorf("create %s: %w", ConfigFile, err)
+	}
+	defer f.Close()
+
+	// loopback first
+	if lo, ok := configs["lo"]; ok {
+		writeStanza(f, lo)
+	}
+	for name, cfg := range configs {
+		if name == "lo" {
+			continue
+		}
+		writeStanza(f, cfg)
+	}
+	return nil
+}
+
+func writeStanza(f *os.File, c *InterfaceConfig) {
+	if c.Auto {
+		fmt.Fprintf(f, "auto %s\n", c.Name)
+	}
+	family := "inet"
+	fmt.Fprintf(f, "iface %s %s %s\n", c.Name, family, c.Mode)
+
+	if c.Mode == "static" {
+		if c.Address != "" {
+			fmt.Fprintf(f, "\taddress %s\n", c.Address)
+		}
+		if c.Netmask != "" {
+			fmt.Fprintf(f, "\tnetmask %s\n", c.Netmask)
+		}
+		if c.Gateway != "" {
+			fmt.Fprintf(f, "\tgateway %s\n", c.Gateway)
+		}
+		if len(c.DNS) > 0 {
+			fmt.Fprintf(f, "\tdns-nameservers %s\n", strings.Join(c.DNS, " "))
+		}
+	}
+	for k, v := range c.Extra {
+		fmt.Fprintf(f, "\t%s %s\n", k, v)
+	}
+	fmt.Fprintln(f)
+}