working on adding lease handouts

server/BUILD.bazel

@@ -5,6 +5,8 @@ go_library(
     srcs = [
         "ifi.go",
         "ifi_linux.go",
+        "lease_state.go",
+        "pools.go",
         "server.go",
     ],
     importpath = "git.wntrmute.dev/kyle/kdhcp/server",
@@ -12,6 +14,8 @@ go_library(
     deps = [
         "//config",
         "//dhcp",
+        "//iptools",
         "@dev_wntrmute_git_kyle_goutils//syslog",
+        "@in_gopkg_yaml_v2//:yaml_v2",
     ],
 )

server/lease_state.go

@@ -0,0 +1,62 @@
+package server
+
+import (
+	"fmt"
+	"os"
+
+	log "git.wntrmute.dev/kyle/goutils/syslog"
+	"git.wntrmute.dev/kyle/kdhcp/iptools"
+	"gopkg.in/yaml.v2"
+)
+
+type LeaseState struct {
+	Pools  map[string]*iptools.Pool      `yaml:"pools"`
+	Static map[string]*iptools.LeaseInfo `yaml:"static"`
+}
+
+func (srv *Server) SaveLeases() error {
+	leaseFile, err := os.Create(srv.Config.LeaseFile)
+	if err != nil {
+		return fmt.Errorf("server: while saving leases: %w", err)
+	}
+	defer leaseFile.Close()
+	encoder := yaml.NewEncoder(leaseFile)
+
+	state := &LeaseState{
+		Pools:  srv.Pools,
+		Static: srv.Static,
+	}
+
+	if err = encoder.Encode(state); err != nil {
+		return fmt.Errorf("server: while saving leases: %w", err)
+	}
+
+	if err = encoder.Close(); err != nil {
+		return fmt.Errorf("server: while saving leases: %w", err)
+	}
+
+	return nil
+}
+
+func (srv *Server) LoadLeases() error {
+	leaseState := &LeaseState{}
+	leaseFile, err := os.Open(srv.Config.LeaseFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			log.Warningf("server: not loading leases from %s: lease file not found", srv.Config.LeaseFile)
+			return nil
+		}
+
+		return fmt.Errorf("server: while reading leases: %w", err)
+	}
+	defer leaseFile.Close()
+	decoder := yaml.NewDecoder(leaseFile)
+
+	if err = decoder.Decode(leaseState); err != nil {
+		return fmt.Errorf("server: while reading leases: %w", err)
+	}
+
+	srv.Pools = leaseState.Pools
+	srv.Static = leaseState.Static
+	return nil
+}

server/pools.go

@@ -0,0 +1,37 @@
+package server
+
+import (
+	"fmt"
+	"net/netip"
+
+	log "git.wntrmute.dev/kyle/goutils/syslog"
+	"git.wntrmute.dev/kyle/kdhcp/iptools"
+)
+
+// pools.go adds pool functionality to the server.
+
+func (srv *Server) loadPoolsFromConfig() error {
+	for host, ip := range srv.Config.Statics {
+		addr, ok := netip.AddrFromSlice(ip.To4())
+		if !ok {
+			return fmt.Errorf("server: while instantiating pools, could not load IP %s", ip)
+		}
+		log.Debugf("server: added static host entry %s -> %s", host, addr)
+		srv.Static[host] = &iptools.LeaseInfo{
+			HostName: host,
+			Addr:     addr,
+		}
+	}
+
+	for name, ipRange := range srv.Config.Pools {
+		pool, err := iptools.NewPool(name, ipRange)
+		if err != nil {
+			return fmt.Errorf("server: couldn't load pool %s: %w", name, err)
+		}
+		log.Debugf("server: added pool %s: %s -> %s", name, ipRange.Start, ipRange.End)
+
+		srv.Pools[name] = pool
+	}
+
+	return nil
+}

server/server.go

@@ -3,19 +3,25 @@ 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 (
-	MaxPacketSize = 512
+	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 {
@@ -24,6 +30,8 @@ func (s *Server) Close() error {
 
 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
@@ -46,7 +54,7 @@ func (s *Server) ReadDHCPRequest() (*dhcp.BootRequest, error) {
 		return nil, err
 	}
 
-	log.Debugf("server: read %db packet from %s", len(pkt), addr)
+	log.Debugf("server: read packet from %s", addr)
 	return dhcp.ReadRequest(pkt)
 }
 
@@ -77,10 +85,19 @@ func (s *Server) Listen() {
 func New(cfg *config.Config) (*Server, error) {
 	srv := &Server{
 		Config: cfg,
+		Pools:  map[string]*iptools.Pool{},
+		Static: map[string]*iptools.LeaseInfo{},
 	}
 
-	err := srv.Bind()
-	if err != nil {
+	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
 	}
 
@@ -88,3 +105,19 @@ func New(cfg *config.Config) (*Server, error) {
 
 	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
+}