Fix DHCP client unable to get IP and config not persisting

- Fixed verifyAssignment being too strict for new clients
- Fixed parseRequestedIP string conversion bug
- Fixed response sent to 0.0.0.0 instead of broadcast address
- Added SO_BROADCAST support for UDP socket
- Fixed session persistence after page refresh (localStorage)
- Added in-memory session store for auth middleware
- Added config reloader so DHCP server picks up web UI changes dynamically

internal/db/database.go

@@ -0,0 +1,123 @@
+package db
+
+import (
+	"time"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type DB struct {
+	*gorm.DB
+}
+
+type DHCPLease struct {
+	ID        uint   `gorm:"primaryKey"`
+	MAC       string `gorm:"index"`
+	IP        string
+	Hostname  string
+	ExpiresAt int64
+}
+
+type DHCPStaticBinding struct {
+	ID          uint   `gorm:"primaryKey"`
+	MAC         string `gorm:"uniqueIndex"`
+	IP          string `gorm:"uniqueIndex"`
+	Hostname    string
+	Description string
+	Enabled     bool
+}
+
+type DNSZone struct {
+	ID   uint   `gorm:"primaryKey"`
+	Name string `gorm:"uniqueIndex"`
+	Type string // master, slave, forward
+}
+
+type DNSRecord struct {
+	ID        uint   `gorm:"primaryKey"`
+	ZoneID    uint
+	Zone      DNSZone
+	Name      string `gorm:"index"`
+	Type      string // A, CNAME, MX, TXT
+	Value     string
+	TTL       int
+	Enabled   bool
+}
+
+type DNSQueryLog struct {
+	ID        uint   `gorm:"primaryKey"`
+	ClientIP  string
+	QueryName string
+	QueryType string
+	Response  string
+	Timestamp int64
+}
+
+func InitDB(path string) (*DB, error) {
+	db, err := gorm.Open(sqlite.Open(path), &gorm.Config{})
+	if err != nil {
+		return nil, err
+	}
+
+	// Auto migrate
+	err = db.AutoMigrate(
+		&DHCPLease{},
+		&DHCPStaticBinding{},
+		&DNSZone{},
+		&DNSRecord{},
+		&DNSQueryLog{},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &DB{db}, nil
+}
+
+func (d *DB) GetActiveLeases() ([]DHCPLease, error) {
+	var leases []DHCPLease
+	err := d.Where("expires_at > ?", time.Now().Unix()).Find(&leases).Error
+	return leases, err
+}
+
+func (d *DB) GetStaticBindings() ([]DHCPStaticBinding, error) {
+	var bindings []DHCPStaticBinding
+	err := d.Where("enabled = ?", true).Find(&bindings).Error
+	return bindings, err
+}
+
+func (d *DB) GetDNSRecords() ([]DNSRecord, error) {
+	var records []DNSRecord
+	err := d.Where("enabled = ?", true).Preload("Zone").Find(&records).Error
+	return records, err
+}
+
+func (d *DB) GetDNSZones() ([]DNSZone, error) {
+	var zones []DNSZone
+	err := d.Find(&zones).Error
+	return zones, err
+}
+
+func (d *DB) CreateDNSZone(name, zoneType string) error {
+	zone := DNSZone{
+		Name: name,
+		Type: zoneType,
+	}
+	return d.Create(&zone).Error
+}
+
+func (d *DB) DeleteDNSZone(id uint) error {
+	return d.Delete(&DNSZone{}, id).Error
+}
+
+func (d *DB) AddQueryLog(clientIP, queryName, queryType, response string) error {
+	log := DNSQueryLog{
+		ClientIP:  clientIP,
+		QueryName: queryName,
+		QueryType: queryType,
+		Response:  response,
+		Timestamp: time.Now().Unix(),
+	}
+	return d.Create(&log).Error
+}