config: writing how the config file should look

.gitignore

@@ -2,3 +2,6 @@ bazel-bin
 bazel-kdhcp
 bazel-out
 bazel-testlogs
+
+kdhcpd
+cmd/kdhcpd/kdhcpd

cmd/kdhcpd/main.go

@@ -1,36 +1,34 @@
 package main
 
 import (
+	"context"
 	"flag"
+	"os"
 
+	"git.wntrmute.dev/kyle/kdhcp/bazel-kdhcp/external/com_github_davecgh_go_spew/spew"
+	"git.wntrmute.dev/kyle/kdhcp/config"
 	"git.wntrmute.dev/kyle/kdhcp/log"
-	"git.wntrmute.dev/kyle/kdhcp/server"
+	"github.com/peterbourgon/ff/v3/ffcli"
-	"github.com/davecgh/go-spew/spew"
 )
 
 func main() {
-	cfg := server.DefaultConfig()
+	var configPath string
-	var level, tag string
+
-	flag.StringVar(&level, "l", "DEBUG", "log level") // TODO(kyle): change this warning later
+	flag.StringVar(&configPath, "f", "kdhcpd.yaml", "path to `config file`")
-	flag.IntVar(&cfg.Port, "p", cfg.Port, "port to listen on")
-	flag.StringVar(&tag, "t", "kdhcpd", "logging tag")
 	flag.Parse()
 
-	log.Setup(level, tag)
+	root := &ffcli.Command{
+		Exec: func(ctx context.Context, args []string) error {
+			cfg, err := config.Load(configPath)
+			if err != nil {
+				log.Fatal(err)
+			}
 
-	srv, err := server.NewServer(cfg)
+			log.Debugf("read configuration file with version=%d", cfg.Version)
-	if err != nil {
+			spew.Dump(*cfg)
-		log.Fatal(err)
+			return nil
+		},
 	}
 
-	for {
+	root.ParseAndRun(context.Background(), os.Args[1:])
-		packet, err := srv.ReadFrom()
-		if err != nil {
-			log.Warning(err)
-			continue
-		}
-
-		log.Debugf("receive %d byte packet from %s", len(packet.Data), packet.Addr)
-		spew.Dump(packet.Data)
-	}
 }

config/config.go

@@ -0,0 +1,147 @@
+package config
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net"
+
+	"git.wntrmute.dev/kyle/kdhcp/log"
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	CurrentVersion = 1
+)
+
+func ensureV4(ip net.IP) (net.IP, error) {
+	ip4 := ip.To4()
+	if ip4 == nil {
+		return ip4, fmt.Errorf("%s isn't an IPv4 address", ip)
+	}
+
+	return ip4, nil
+}
+
+type IPRange struct {
+	Start net.IP
+	End   net.IP
+}
+
+func (r *IPRange) ensureV4() (err error) {
+	if r.Start, err = ensureV4(r.Start); err != nil {
+		return fmt.Errorf("config: range start address %w", err)
+	}
+
+	if r.End, err = ensureV4(r.End); err != nil {
+		return fmt.Errorf("config: range end address %w", err)
+	}
+
+	return nil
+}
+
+type Network struct {
+	Gateway   net.IP   `yaml:"gateway"`
+	Mask      net.IP   `yaml:"mask"`
+	Broadcast net.IP   `yaml:"broadcast"`
+	DNS       []net.IP `yaml:"dns"`
+	Domain    string   `yaml:"domain"`
+}
+
+func (n *Network) ensureV4() (err error) {
+	n.Gateway, err = ensureV4(n.Gateway)
+	if err != nil {
+		return fmt.Errorf("config: gateway %w", err)
+	}
+
+	n.Mask, err = ensureV4(n.Mask)
+	if err != nil {
+		return fmt.Errorf("config: mask  %w", err)
+	}
+
+	n.Broadcast, err = ensureV4(n.Broadcast)
+	if err != nil {
+		return fmt.Errorf("config: broadcast  %w", err)
+	}
+
+	for i := range n.DNS {
+		n.DNS[i], err = ensureV4(n.DNS[i])
+		if err != nil {
+			return fmt.Errorf("config: DNS address %w", err)
+		}
+	}
+
+	return nil
+}
+
+type ConfigFile struct {
+	Server *Config `yaml:"kdhcp"`
+}
+
+type Config struct {
+	Version   int                 `yaml:"version"`
+	Interface string              `yaml:"interface"`
+	LeaseFile string              `yaml:"lease_file"`
+	Network   *Network            `yaml:"network"`
+	Pools     map[string]*IPRange `yaml:"pools"`
+	Statics   map[string]net.IP   `yaml:"statics"`
+	Device    *net.Interface
+}
+
+func (cfg *Config) process() (err error) {
+	switch {
+	case cfg.Version == 0:
+		log.Warningln("config: Version is 0, which indicates it hasn't been set. The config may be invalid.")
+	case cfg.Version > CurrentVersion:
+		log.Warningf("config: Version is greater than the current version %d. The config may not behave as expected.", CurrentVersion)
+	}
+
+	cfg.Device, err = net.InterfaceByName(cfg.Interface)
+	if err != nil {
+		return fmt.Errorf("config: while looking up interface %s: %w", cfg.Interface, err)
+	}
+
+	err = cfg.Network.ensureV4()
+	if err != nil {
+		return err
+	}
+
+	for k, v := range cfg.Pools {
+		if err = v.ensureV4(); err != nil {
+			return fmt.Errorf("config: pool %s %w", k, err)
+		}
+
+		cfg.Pools[k] = v
+	}
+
+	for k, v := range cfg.Statics {
+		cfg.Statics[k], err = ensureV4(v)
+		if err != nil {
+			return fmt.Errorf("config: %s %w", k, err)
+		}
+	}
+
+	return nil
+}
+
+func Load(path string) (*Config, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("config: loading %s: %w", path, err)
+	}
+
+	configFile := &ConfigFile{}
+	err = yaml.Unmarshal(data, configFile)
+	if err != nil {
+		return nil, fmt.Errorf("config: while unmarshaling %s: %w", path, err)
+	}
+
+	if configFile.Server == nil {
+		log.Fatal("missing `kdhcp` section of config")
+	}
+	config := configFile.Server
+	if err = config.process(); err != nil {
+		return nil, err
+	}
+
+	return config, nil
+}

go.mod

@@ -5,10 +5,7 @@ go 1.20
 require github.com/hashicorp/go-syslog v1.0.0
 
 require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.1
-	github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16 // indirect
+	github.com/peterbourgon/ff/v3 v3.3.0
-	github.com/josharian/native v1.1.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0
-	github.com/pierrec/lz4/v4 v4.1.14 // indirect
-	github.com/u-root/uio v0.0.0-20230220225925-ffce2a382923 // indirect
-	golang.org/x/sys v0.5.0 // indirect
 )

go.sum

@@ -2,15 +2,9 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/hashicorp/go-syslog v1.0.0 h1:KaodqZuhUoZereWVIYmpUgZysurB1kBLX2j0MwMrUAE=
 github.com/hashicorp/go-syslog v1.0.0/go.mod h1:qPfqrKkXGihmCqbJM2mZgkZGvKG1dFdvsLplgctolz4=
-github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16 h1:+aAGyK41KRn8jbF2Q7PLL0Sxwg6dShGcQSeCC7nZQ8E=
+github.com/peterbourgon/ff/v3 v3.3.0 h1:PaKe7GW8orVFh8Unb5jNHS+JZBwWUMa2se0HM6/BI24=
-github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16/go.mod h1:IKrnDWs3/Mqq5n0lI+RxA2sB7MvN/vbMBP3ehXg65UI=
+github.com/peterbourgon/ff/v3 v3.3.0/go.mod h1:zjJVUhx+twciwfDl0zBcFzl4dW8axCRyXE/eKY9RztQ=
-github.com/josharian/native v1.0.1-0.20221213033349-c1e37c09b531/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
-github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
-github.com/pierrec/lz4/v4 v4.1.14 h1:+fL8AQEZtz/ijeNnpduH0bROTu0O3NZAlPjQxGn8LwE=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
-github.com/pierrec/lz4/v4 v4.1.14/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
-github.com/u-root/uio v0.0.0-20230220225925-ffce2a382923 h1:tHNk7XK9GkmKUR6Gh8gVBKXc2MVSZ4G/NnWLtzw4gNA=
-github.com/u-root/uio v0.0.0-20230220225925-ffce2a382923/go.mod h1:eLL9Nub3yfAho7qB0MzZizFhTU2QkLeoVsWdHtDW264=
-golang.org/x/sys v0.0.0-20220622161953-175b2fd9d664/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.5.0 h1:MUK/U/4lj1t1oPg0HfuXDN/Z1wv31ZJ/YcPiGccS4DU=
-golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

kdhcpd.yaml

@@ -0,0 +1,27 @@
+kdhcp:
+  version: 1
+  lease_file: /tmp/kdhcp_lease.yaml
+    #  interface: enp89s0
+  interface: wlp166s0
+  network:
+    gateway: 192.168.4.254
+    mask: 255.255.255.0
+    broadcast: 192.168.4.255
+    dns:
+      - 1.1.1.1
+      - 8.8.8.8
+    domain: cluster.wntrmute.dev
+  pools:
+    cluster:
+      start: 192.168.4.1
+      end:   192.168.4.32
+    controller:
+      start: 192.168.4.64
+      end:   192.168.4.68
+    default:
+      start: 192.168.4.128
+      end:   192.168.4.164
+  statics:
+    controller: 192.168.4.254
+    haven:      192.168.4.253
+    build01:	192.168.4.252

server/BUILD.bazel

@@ -1,13 +0,0 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
-
-go_library(
-    name = "server",
-    srcs = [
-        "config.go",
-        "packet.go",
-        "server.go",
-    ],
-    importpath = "git.wntrmute.dev/kyle/kdhcp/server",
-    visibility = ["//visibility:public"],
-    deps = ["//log"],
-)

server/config.go

@@ -1,19 +0,0 @@
-package server
-
-const (
-	DefaultPort          = 67
-	DefaultMaxPacketSize = 512
-	DefaultNetwork       = "udp4"
-)
-
-type Config struct {
-	Port          int
-	MaxPacketSize int
-}
-
-func DefaultConfig() *Config {
-	return &Config{
-		Port:          DefaultPort,
-		MaxPacketSize: DefaultMaxPacketSize,
-	}
-}

server/packet.go

@@ -1,14 +0,0 @@
-package server
-
-import (
-	"net"
-
-	"github.com/insomniacslk/dhcp/dhcpv4"
-)
-
-type Packet struct {
-	Data []byte
-	Addr net.Addr
-
-	Raw *dhcpv4.DHCPv4
-}

server/server.go

@@ -1,67 +0,0 @@
-package server
-
-import (
-	"fmt"
-	"net"
-
-	"git.wntrmute.dev/kyle/kdhcp/log"
-	"github.com/insomniacslk/dhcp/dhcpv4"
-)
-
-type Server struct {
-	cfg  *Config
-	conn net.PacketConn
-}
-
-func (srv *Server) Listen() (err error) {
-	if srv.conn != nil {
-		srv.conn.Close()
-	}
-
-	log.Debugf("attempting to set up packet listener on %s 0.0.0.0:%d", DefaultNetwork, srv.cfg.Port)
-	srv.conn, err = net.ListenPacket(DefaultNetwork, fmt.Sprintf(":%d", srv.cfg.Port))
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (srv *Server) Close() error {
-	if srv.conn != nil {
-		return srv.conn.Close()
-	}
-	return nil
-}
-
-func (srv *Server) ReadFrom() (*Packet, error) {
-	b := make([]byte, srv.cfg.MaxPacketSize)
-	n, addr, err := srv.conn.ReadFrom(b)
-	if err != nil {
-		return nil, err
-	}
-
-	packet := &Packet{
-		Data: b[:n],
-		Addr: addr,
-	}
-	packet.Raw, err = dhcpv4.FromBytes(b[:n])
-	if err != nil {
-		return packet, err
-	}
-
-	return packet, nil
-}
-
-func NewServer(cfg *Config) (*Server, error) {
-	srv := &Server{
-		cfg: cfg,
-	}
-
-	err := srv.Listen()
-	if err != nil {
-		return nil, err
-	}
-
-	return srv, nil
-}