iptools: reorganizing and continuing pool work

.gitignore

@@ -5,3 +5,4 @@ bazel-testlogs
 
 kdhcpd
 cmd/kdhcpd/kdhcpd
+strace.txt

config/BUILD.bazel

@@ -9,6 +9,7 @@ go_library(
     importpath = "git.wntrmute.dev/kyle/kdhcp/config",
     visibility = ["//visibility:public"],
     deps = [
+        "//iptools",
         "//log",
         "@in_gopkg_yaml_v2//:yaml_v2",
     ],

config/config.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"net"
 
+	"git.wntrmute.dev/kyle/kdhcp/iptools"
 	"git.wntrmute.dev/kyle/kdhcp/log"
 	"gopkg.in/yaml.v2"
 )
@@ -23,23 +24,6 @@ func ensureV4(ip net.IP) (net.IP, error) {
 	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 {
 	IP        net.IP   `yaml:"address"`
 	Gateway   net.IP   `yaml:"gateway"`
@@ -91,7 +75,7 @@ type Config struct {
 	Port      int                       `yaml:"port"`
 	LeaseFile string                    `yaml:"lease_file"`
 	Network   *Network                  `yaml:"network"`
-	Pools     map[string]*IPRange `yaml:"pools"`
+	Pools     map[string]*iptools.Range `yaml:"pools"`
 	Statics   map[string]net.IP         `yaml:"statics"`
 }
 
@@ -114,7 +98,7 @@ func (cfg *Config) process() (err error) {
 	}
 
 	for k, v := range cfg.Pools {
-		if err = v.ensureV4(); err != nil {
+		if err = v.Validate(); err != nil {
 			return fmt.Errorf("config: pool %s %w", k, err)
 		}
 

dhcp/options.go

@@ -2,6 +2,7 @@ package dhcp
 
 import (
 	"errors"
+	"fmt"
 	"io"
 )
 
@@ -11,14 +12,14 @@ type Option func(req *BootRequest, r io.Reader) error
 
 const (
 	OptionTagPadding              OptionTag = 0
-	OptionTagHostName                       = 12
-	OptionTagMessageType                    = 53
-	OptionTagParameterRequestList           = 55
-	OptionTagEnd                            = 255
+	OptionTagHostName             OptionTag = 12
+	OptionTagMessageType          OptionTag = 53
+	OptionTagParameterRequestList OptionTag = 55
+	OptionTagEnd                  OptionTag = 255
 )
 
 var optionRegistry = map[OptionTag]Option{
-	OptionTagPadding:              OptionTag,
+	OptionTagPadding:              OptionPad,
 	OptionTagHostName:             OptionHostName,
 	OptionTagMessageType:          OptionMessageType,
 	OptionTagParameterRequestList: OptionParameterRequestList,
@@ -44,3 +45,13 @@ func OptionParameterRequestList(req *BootRequest, r io.Reader) error {
 func OptionEnd(req *BootRequest, r io.Reader) error {
 	return errors.New("dhcp: option not implemented yet")
 }
+
+func ReadOption(req *BootRequest, tag byte, r io.Reader) error {
+	opt := OptionTag(tag)
+	if f, ok := optionRegistry[opt]; ok {
+		return f(req, r)
+
+	}
+
+	return fmt.Errorf("dhcp: unknown/unhandled option %d", opt)
+}

iptools/BUILD.bazel

@@ -0,0 +1,17 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "iptools",
+    srcs = [
+        "pool.go",
+        "range.go",
+    ],
+    importpath = "git.wntrmute.dev/kyle/kdhcp/iptools",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "iptools_test",
+    srcs = ["range_test.go"],
+    embed = [":iptools"],
+)

iptools/hardware_address.go

@@ -0,0 +1,41 @@
+package iptools
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+type HardwareAddress []byte
+
+func (mac HardwareAddress) String() string {
+	marshalled := []string{}
+	for i := 0; i < len(mac); i++ {
+		marshalled = append(marshalled, fmt.Sprintf("%02x", []byte(mac[i:i+1])))
+	}
+
+	return strings.Join(marshalled, ":")
+}
+
+func (mac HardwareAddress) MarshalText() ([]byte, error) {
+	return []byte(mac.String()), nil
+}
+
+func (mac *HardwareAddress) UnmarshalText(b []byte) error {
+	rb := bytes.Split(b, []byte(":"))
+	for _, octet := range rb {
+		n, err := strconv.ParseUint(string(octet), 16, 8)
+		if err != nil {
+			return err
+		}
+
+		*mac = append(*mac, uint8(n))
+	}
+
+	return nil
+}
+
+func (mac HardwareAddress) Match(other HardwareAddress) bool {
+	return bytes.Equal(mac, other)
+}

iptools/hardware_address_test.go

@@ -0,0 +1,31 @@
+package iptools
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestHardwareMacMarshalling(t *testing.T) {
+	macString := "b8:27:eb:b6:a1:a7"
+	mac := HardwareAddress([]byte{0xb8, 0x27, 0xeb, 0xb6, 0xa1, 0xa7})
+
+	b, err := mac.MarshalText()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s := string(b)
+	if s != macString {
+		t.Fatalf("have %s, want %s", s, macString)
+	}
+
+	mac2 := &HardwareAddress{}
+	err = mac2.UnmarshalText(b)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(*mac2, mac) {
+		t.Fatalf("have %x, want %x", *mac2, mac)
+	}
+}

iptools/lease_info.go

@@ -0,0 +1,69 @@
+package iptools
+
+import (
+	"fmt"
+	"net/netip"
+	"sort"
+	"strings"
+	"time"
+)
+
+type LeaseInfo struct {
+	HostName        string          `yaml:"hostname"`
+	Addr            netip.Addr      `yaml:"addr"`
+	HardwareAddress HardwareAddress `yaml:"mac_addr"`
+	Expires         time.Time       `yaml:"expires"`
+}
+
+type sortableLease []LeaseInfo
+
+func (a sortableLease) Len() int           { return len(a) }
+func (a sortableLease) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a sortableLease) Less(i, j int) bool { return a[i].Addr.Less(a[j].Addr) }
+
+func (li *LeaseInfo) ResetExpiry(t time.Time, dur time.Duration) {
+	li.Expires = t.Add(dur)
+}
+
+func (li *LeaseInfo) IsExpired(t time.Time) bool {
+	return t.After(li.Expires)
+}
+
+func (li *LeaseInfo) Expire() {
+	li.Expires = time.Time{}
+}
+
+func SortLeases(leases []LeaseInfo) []LeaseInfo {
+	sortable := sortableLease(leases)
+	sort.Sort(sortable)
+
+	return []LeaseInfo(sortable)
+}
+
+func (lease LeaseInfo) Reset() LeaseInfo {
+	lease.Expires = time.Time{}
+	lease.HardwareAddress = nil
+	return lease
+}
+
+func (lease LeaseInfo) Compare(other LeaseInfo) error {
+	susFields := []string{}
+
+	if lease.Addr != other.Addr {
+		susFields = append(susFields, fmt.Sprintf("address is %s, but is recorded as %s", lease.Addr, other.Addr))
+	}
+
+	if !lease.HardwareAddress.Match(other.HardwareAddress) {
+		susFields = append(susFields, fmt.Sprintf("hardware address is %s, but is recorded as %s", lease.HardwareAddress, other.HardwareAddress))
+	}
+
+	if lease.HostName != other.HostName {
+		susFields = append(susFields, fmt.Sprintf("hostname is %s, but is recorded as %s", lease.HostName, other.HostName))
+	}
+
+	if len(susFields) > 0 {
+		return fmt.Errorf("suspicious lease: %s", strings.Join(susFields, ";"))
+	}
+
+	return nil
+}

iptools/pool_test.go

@@ -0,0 +1,37 @@
+package iptools
+
+import (
+	"fmt"
+	"net/netip"
+	"testing"
+	"time"
+)
+
+var (
+	poolTestIP1 = netip.MustParseAddr("192.168.4.1")
+	poolTestIP2 = netip.MustParseAddr("192.168.4.32")
+)
+
+func TestBasicPool(t *testing.T) {
+	r := &Range{
+		Start: poolTestIP1,
+		End:   poolTestIP2,
+	}
+
+	p, err := NewPool("cluster", 24*time.Hour, r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(p.Available) != 32 {
+		t.Fatalf("have %d available leases, want %d", len(p.Available), 32)
+	}
+
+	for i := range p.Available {
+		l := p.Available[i]
+		expectedName := fmt.Sprintf("cluster%02d", l.Addr.As4()[3])
+		if l.HostName != expectedName {
+			t.Fatalf("have hostname %s, want %s", l.HostName, expectedName)
+		}
+	}
+}

iptools/range.go

@@ -0,0 +1,61 @@
+package iptools
+
+import (
+	"fmt"
+	"net/netip"
+)
+
+const (
+	DefaultMaskBits = 24
+)
+
+type Range struct {
+	Start   netip.Addr   `yaml:"start"`
+	End     netip.Addr   `yaml:"end"`
+	Network netip.Prefix `yaml:"network"`
+}
+
+func (r *Range) Validate() error {
+	if !r.Start.Is4() {
+		return fmt.Errorf("range start %s is not a valid IPv4 address", r.Start)
+	}
+
+	if !r.End.Is4() {
+		return fmt.Errorf("range end %s is not a valid IPv4 address", r.End)
+	}
+
+	// Compare returns -1 if lhs < rhs, 0 if lhs == rhs, and 1 if lhs > rhs.
+	if r.End.Compare(r.Start) != 1 {
+		return fmt.Errorf("start address %s is not before end address %s", r.Start, r.End)
+	}
+
+	var err error
+	if !r.Network.IsValid() {
+		r.Network, err = r.Start.Prefix(DefaultMaskBits)
+		if err != nil {
+			return err
+		}
+	}
+
+	if !r.Network.Contains(r.Start) {
+		return fmt.Errorf("prefix %s does not contain start address %s", r.Network, r.Start)
+	}
+
+	if !r.Network.Contains(r.End) {
+		return fmt.Errorf("prefix %s does not contain end address %s", r.Network, r.End)
+	}
+
+	return nil
+}
+
+// this is probably dumb, but it's a one-time cost upfront on pool instantiation.
+func (r *Range) numHosts() int {
+	cur := r.Start
+	hosts := 0
+	for cur.Compare(r.End) < 1 {
+		hosts++
+		cur.Next()
+	}
+
+	return hosts
+}

iptools/range_test.go

@@ -0,0 +1,49 @@
+package iptools
+
+import (
+	"net/netip"
+	"testing"
+)
+
+var (
+	rangeTestIP1 = netip.AddrFrom4([4]byte{192, 168, 4, 3})
+	rangeTestIP2 = netip.AddrFrom4([4]byte{192, 168, 4, 17})
+)
+
+func TestBasicValidation(t *testing.T) {
+	r1 := &Range{
+		Start: rangeTestIP1,
+		End:   rangeTestIP2,
+	}
+
+	if err := r1.Validate(); err != nil {
+		t.Fatalf("range 1 should be valid: %s", err)
+	}
+
+	r2 := &Range{
+		Start: rangeTestIP2,
+		End:   rangeTestIP1,
+	}
+
+	if r2.Validate() == nil {
+		t.Fatal("range 2 should be invalid")
+	}
+
+	r3 := &Range{
+		Start: netip.IPv6LinkLocalAllRouters(),
+		End:   rangeTestIP1,
+	}
+
+	if r3.Validate() == nil {
+		t.Fatal("range 3 should be invalid")
+	}
+
+	r4 := &Range{
+		Start: rangeTestIP2,
+		End:   netip.IPv6LinkLocalAllRouters(),
+	}
+
+	if r4.Validate() == nil {
+		t.Fatal("range 4 should be invalid")
+	}
+}

iptools/tools.go

@@ -0,0 +1,25 @@
+package iptools
+
+import "fmt"
+
+func enumerateRange(name string, r *Range, startFromOne bool) []LeaseInfo {
+	start := r.Start
+	cur := start
+	lenfmt := fmt.Sprintf("%%s%%0%dd", len(fmt.Sprintf("%d", r.numHosts())))
+	i := 0
+	if startFromOne {
+		i++
+	}
+	leases := []LeaseInfo{}
+
+	for r.End.Compare(cur) >= 0 {
+		leases = append(leases, LeaseInfo{
+			HostName: fmt.Sprintf(lenfmt, name, i),
+			Addr:     cur,
+		})
+		i++
+		cur = cur.Next()
+	}
+
+	return leases
+}

server/BUILD.bazel

@@ -4,6 +4,7 @@ go_library(
     name = "server",
     srcs = [
         "ifi.go",
+        "ifi_linux.go",
         "server.go",
     ],
     importpath = "git.wntrmute.dev/kyle/kdhcp/server",

server/server.go

@@ -70,6 +70,7 @@ func (s *Server) Listen() {
 			log.Errf("server: error reading packet: %s", err)
 			continue
 		}
+		break
 	}
 }