kdhcp/server/server.go

124 lines
2.5 KiB
Go

package server
import (
"errors"
"net"
"time"
log "git.wntrmute.dev/kyle/goutils/syslog"
"git.wntrmute.dev/kyle/kdhcp/config"
"git.wntrmute.dev/kyle/kdhcp/dhcp"
"git.wntrmute.dev/kyle/kdhcp/iptools"
)
const (
DefaultPool = "default"
MaxPacketSize = 512
MaxResponseWait = 5 * time.Minute
)
type Server struct {
Conn net.PacketConn
Config *config.Config
Pools map[string]*iptools.Pool
Static map[string]*iptools.LeaseInfo
}
func (s *Server) Close() error {
return s.Conn.Close()
}
func (s *Server) Bind() (err error) {
// In order to read DHCP packets, we'll need to listen on all addresses.
// That being said, we also want to limit our listening to the DHCP
// network device.
ip := net.IP([]byte{0, 0, 0, 0})
s.Conn, err = BindInterface(ip, s.Config.Port, s.Config.Interface)
return err
}
func (s *Server) ReadFrom() ([]byte, net.Addr, error) {
b := make([]byte, MaxPacketSize)
n, addr, err := s.Conn.ReadFrom(b)
if err != nil {
return nil, nil, err
}
b = b[:n]
return b, addr, nil
}
func (s *Server) ReadDHCPRequest() (*dhcp.BootRequest, error) {
pkt, addr, err := s.ReadFrom()
if err != nil {
return nil, err
}
log.Debugf("server: read packet from %s", addr)
return dhcp.ReadRequest(pkt)
}
func (s *Server) WriteTo(b []byte, addr net.Addr) error {
return errors.New("server: not implemented")
}
func (s *Server) AcceptPacket() error {
request, err := s.ReadDHCPRequest()
if err != nil {
return err
}
log.Debugf("BOOTP request received from %x", request.HardwareAddress)
return nil
}
func (s *Server) Listen() {
for {
if err := s.AcceptPacket(); err != nil {
log.Errf("server: error reading packet: %s", err)
continue
}
break
}
}
func New(cfg *config.Config) (*Server, error) {
srv := &Server{
Config: cfg,
Pools: map[string]*iptools.Pool{},
Static: map[string]*iptools.LeaseInfo{},
}
if err := srv.loadPoolsFromConfig(); err != nil {
return nil, err
}
if err := srv.LoadLeases(); err != nil {
return nil, err
}
if err := srv.Bind(); err != nil {
return nil, err
}
log.Infof("server: bound to %s:%s", cfg.Interface, srv.Conn.LocalAddr())
return srv, nil
}
func (srv *Server) SelectLease(req *dhcp.BootRequest, t time.Time) *iptools.LeaseInfo {
if li, ok := srv.Static[req.HostName]; ok {
return li
}
if pool, ok := srv.Pools[req.HostName]; ok {
return pool.Peek(t, MaxResponseWait)
}
if pool, ok := srv.Pools[DefaultPool]; ok {
return pool.Peek(t, MaxResponseWait)
}
return nil
}