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dhcp->dhcpv4; finish NTP and DHCPv4 clients

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This commit is contained in:
soypat
2024-12-26 11:55:27 -03:00
parent c99076cd0b
commit 7f03c1c0a6
9 changed files with 370 additions and 124 deletions
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lneto/dhcp/client.go
-56
View File
@@ -1,56 +0,0 @@
package dhcp
import (
"io"
)
type ClientV4 struct {
reqHostname []byte
hostname []byte
offer [4]byte
svip [4]byte
reqIP [4]byte
dns [4]byte
router [4]byte
subnet [4]byte
broadcast [4]byte
gateway [4]byte
optbuf [10]Option
currentXID uint32
tRenew uint32
tRebind uint32
tIPLease uint32
state ClientState
}
type RequestConfig struct {
RequestedAddr [4]byte
// Optional hostname to request.
Hostname string
}
func (c *ClientV4) BeginRequest(xid uint32, cfg RequestConfig) error {
c.currentXID = xid
c.reqHostname = append(c.reqHostname[:0], cfg.Hostname...)
c.reqIP = cfg.RequestedAddr
return nil
}
func (c *ClientV4) Write(dst []byte) (int, error) {
if c.isClosed() {
return 0, io.EOF
}
frm, err := NewFrameV4(dst)
if err != nil {
return 0, err
}
// var options []Option
// var nextState ClientState
switch c.state {
case StateInit:
frm.MagicCookie()
}
return 0, nil
}
func (c *ClientV4) isClosed() bool { return c.state == 0 }
lneto/dhcpv4/client.go
+260
View File
@@ -0,0 +1,260 @@
package dhcpv4
import (
"encoding/binary"
"errors"
"fmt"
"io"
"math"
"math/bits"
)
type Client struct {
reqHostname string
hostname []byte
dns [][4]byte
tRenew uint32
tRebind uint32
tIPLease uint32
currentXID uint32
state ClientState
offer [4]byte
svip [4]byte
reqIP [4]byte
router [4]byte
subnet [4]byte
broadcast [4]byte
gateway [4]byte
clientMAC [6]byte
auxbuf [64]byte
}
type RequestConfig struct {
RequestedAddr [4]byte
ClientHardwareAddr [6]byte
// Optional hostname to request.
Hostname string
}
func (c *Client) BeginRequest(xid uint32, cfg RequestConfig) error {
if len(cfg.Hostname) > 36 {
return errors.New("requested hostname too long")
}
c.reset(xid)
c.currentXID = xid
c.reqHostname = cfg.Hostname
c.reqIP = cfg.RequestedAddr
c.clientMAC = cfg.ClientHardwareAddr
return nil
}
func (c *Client) Send(dst []byte) (int, error) {
if c.isClosed() {
return 0, io.EOF
} else if c.state == StateSelecting && c.offer == [4]byte{} {
return 0, nil // No offer received yet.
} else if c.state == StateBound {
return 0, nil // Done!
}
frm, err := NewFrame(dst)
if err != nil {
return 0, err
}
// var options []Option
// var nextState ClientState
optBuf := c.auxbuf[:0]
var nextState ClientState
switch c.state {
case StateInit:
// Send out discover.
optBuf = AppendOption(optBuf, OptMessageType, byte(MsgDiscover))
optBuf = AppendOption(optBuf, OptParameterRequestList, defaultParamReqList...)
optBuf = AppendOption(optBuf, OptClientIdentifier, c.clientMAC[:]...)
maxlen := len(dst)
if maxlen > math.MaxUint16 {
maxlen = math.MaxUint16
}
optBuf = AppendOption(optBuf, OptMaximumMessageSize, byte(maxlen>>8), byte(maxlen))
if c.reqIP != [4]byte{} {
optBuf = AppendOption(optBuf, OptRequestedIPaddress, c.reqIP[:]...)
}
nextState = StateSelecting
case StateSelecting:
// Send out request, we know we've received an offer by now.
optBuf = AppendOption(optBuf, OptMessageType, byte(MsgRequest))
optBuf = AppendOption(optBuf, OptRequestedIPaddress, c.offer[:]...)
optBuf = AppendOption(optBuf, OptServerIdentification, c.svip[:]...)
nextState = StateRequesting
default:
return 0, errors.New("unhandled state")
}
if len(c.reqHostname) > 0 {
optBuf = append(optBuf, byte(OptHostName), byte(len(c.hostname)))
optBuf = append(optBuf, c.hostname...)
}
optBuf = append(optBuf, 0xff) // End mark.
options := frm.OptionsPayload()
if len(optBuf) > len(options) {
return 0, errors.New("DHCPv4 short buffer for options")
}
c.setHeader(frm)
n := copy(options, optBuf)
c.state = nextState
return optionsOffset + n, nil
}
func (c *Client) Recv(pkt []byte) error {
if c.isClosed() {
return io.EOF
}
frm, err := NewFrame(pkt)
if err != nil {
return err
} else if frm.XID() != c.currentXID {
return errors.New("dhcpv4 unexpected transaction ID")
} else if frm.MagicCookie() != MagicCookie {
return errors.New("dhcpv4 bad magic cookie")
}
msgType := c.getMessageType(frm)
if msgType == MsgNack {
return errors.New("dhcp nack received")
}
msgOK := msgType == MsgOffer || msgType == MsgAck
if !msgOK {
return fmt.Errorf("invalid DHCP message received or none got=%d", msgType)
}
err = c.setOptions(frm)
if err != nil {
return err
}
switch c.state {
case StateSelecting:
if msgType == MsgOffer && c.offer == [4]byte{} {
// Lock in on this offer.
c.gateway = *frm.GIAddr()
c.offer = *frm.YIAddr()
}
case StateRequesting:
if msgType == MsgAck {
c.state = StateBound
}
default:
return fmt.Errorf("dcpv4 unexpected state in recv %s", c.state.String())
}
return nil
}
func (c *Client) getMessageType(frm Frame) MessageType {
c.auxbuf[0] = 255
ptrMsgType := &c.auxbuf[0]
frm.ForEachOption(func(opt OptNum, data []byte) error {
if len(data) == 1 {
*ptrMsgType = data[0]
return io.EOF
}
return nil
})
return MessageType(*ptrMsgType)
}
func (c *Client) setOptions(frm Frame) error {
return frm.ForEachOption(func(opt OptNum, data []byte) error {
switch opt {
case OptRenewTimeValue:
c.tRenew = maybeU32(data)
case OptIPAddressLeaseTime:
c.tIPLease = maybeU32(data)
case OptRebindingTimeValue:
c.tRebind = maybeU32(data)
case OptServerIdentification:
c.svip = maybe4byte(data)
case OptRouter:
c.router = maybe4byte(data)
case OptBroadcastAddress:
c.broadcast = maybe4byte(data)
case OptSubnetMask:
c.subnet = maybe4byte(data)
case OptHostName:
if len(data) < maxHostSize {
c.hostname = append(c.hostname[:0], data...)
}
case OptDNSServers:
if len(c.dns) > 0 || len(data)%4 != 0 {
return nil // No DNS parsing if already got in previous exchange.
}
for i := 0; i < len(data); i += 4 {
c.dns = append(c.dns, [4]byte(data[i:i+4]))
}
}
return nil
})
}
func (c *Client) isClosed() bool { return c.state == 0 || c.currentXID == 0 }
func (c *Client) setHeader(frm Frame) {
frm.ClearHeader()
frm.SetOp(OpRequest)
frm.SetXID(c.currentXID)
frm.SetHardware(1, 6, 0)
frm.SetSecs(1)
// copy(frm.CIAddr()[:], c.offer[:])
copy(frm.SIAddr()[:], c.svip[:])
copy(frm.YIAddr()[:], c.offer[:])
copy(frm.CHAddrAs6()[:], c.clientMAC[:])
frm.SetMagicCookie(MagicCookie)
}
func (c *Client) reset(xid uint32) {
*c = Client{
reqHostname: c.reqHostname,
currentXID: xid,
reqIP: c.reqIP,
clientMAC: c.clientMAC,
}
}
func (d *Client) State() ClientState { return d.state }
func (d *Client) CIDRBits() uint8 {
if d.subnet == [4]byte{} {
return 0
}
v := binary.BigEndian.Uint32(d.subnet[:])
return 32 - uint8(bits.TrailingZeros32(v))
}
var defaultParamReqList = []byte{
byte(OptSubnetMask),
byte(OptTimeOffset),
byte(OptRouter),
byte(OptInterfaceMTUSize),
byte(OptBroadcastAddress),
byte(OptDNSServers),
byte(OptDomainName),
byte(OptNTPServersAddresses),
}
func maybeU32(b []byte) uint32 {
if len(b) < 4 {
return 0
}
return binary.BigEndian.Uint32(b)
}
func maybe4byte(b []byte) [4]byte {
if len(b) != 4 {
return [4]byte{}
}
return [4]byte(b)
}
lneto/dhcp/definitions.go → lneto/dhcpv4/definitions.go
+23 -22
View File
@@ -1,19 +1,18 @@
package dhcp
package dhcpv4
import (
"errors"
"fmt"
)
//go:generate stringer -type=OptNum,Op,MessageType,ClientState -linecomment -output stringers.go
type ClientState uint8
// State transition table:
// ClientState transition table during request:
//
// StateInit -> | Send out Discover | -> StateSelecting
// StateSelecting -> |Accept Offer+Request| -> StateRequesting
// StateRequesting-> | Receive Ack | -> StateBound
type ClientState uint8
const (
_ ClientState = iota
// On clean slate boot, abort, NAK or decline enter the INIT state.
@@ -30,26 +29,26 @@ const (
StateRebooting // rebooting
)
type Option struct {
Num OptNum
Data []byte
func AppendOption(dst []byte, opt OptNum, data ...byte) []byte {
if len(data) > 255 {
panic("option data too long")
}
dst = append(dst, byte(opt), byte(len(data)))
dst = append(dst, data...)
return dst
}
func (opt *Option) String() string {
return opt.Num.String() + ":" + fmt.Sprint(opt.Data)
}
func (opt *Option) Encode(dst []byte) (int, error) {
if len(opt.Data) > 255 {
return 0, errors.New("DHCP option data too long")
} else if len(dst) < 2+len(opt.Data) {
func EncodeOption(dst []byte, opt OptNum, data ...byte) (int, error) {
if len(data) > 255 {
return 0, errors.New("DHCPv4 option data too long (>255)")
} else if len(dst) < 2+len(data) {
return 0, errors.New("DHCP option buffer too short")
}
_ = dst[2+len(opt.Data)]
dst[0] = byte(opt.Num)
dst[1] = byte(len(opt.Data))
copy(dst[2:], opt.Data)
return 2 + len(opt.Data), nil
_ = dst[2+len(data)]
dst[0] = byte(opt)
dst[1] = byte(len(data))
copy(dst[2:], data)
return 2 + len(data), nil
}
type OptNum uint8
@@ -137,7 +136,9 @@ const (
MsgRequest // request
MsgDecline // decline
MsgAck // ack
MsgNak // nak
MsgNack // nak
MsgRelease // release
MsgInform // inform
)
type Flags uint16
lneto/dhcp/frame.go → lneto/dhcpv4/frame.go
+37 -32
View File
@@ -1,4 +1,4 @@
package dhcp
package dhcpv4
import (
"encoding/binary"
@@ -6,6 +6,7 @@ import (
)
const (
maxHostSize = 16 // max size for hostname.
sizeSName = 64 // Server name, part of BOOTP too.
sizeBootFile = 128 // Boot file name, Legacy.
sizeHeader = 44
@@ -20,11 +21,13 @@ const (
DefaultServerPort = 67
)
func NewFrameV4(buf []byte) (FrameV4, error) {
if len(buf) < sizeHeader {
return FrameV4{}, errors.New("DHCP short frame")
// NewFrame returns a new DHCPv4 Frame with data set to buf.
// An error is returned if the buffer size is smaller than 240.
func NewFrame(buf []byte) (Frame, error) {
if len(buf) < optionsOffset {
return Frame{}, errors.New("DHCPv4 short frame")
}
return FrameV4{buf: buf}, nil
return Frame{buf: buf}, nil
}
// Frame encapsulates the raw data of a DHCP packet
@@ -32,79 +35,81 @@ func NewFrameV4(buf []byte) (FrameV4, error) {
// retrieving fields and payload data. See [RFC2131].
//
// [RFC2131]: https://tools.ietf.org/html/rfc2131
type FrameV4 struct {
type Frame struct {
buf []byte
}
func (frm FrameV4) Op() Op {
return Op(frm.buf[0])
// OptionsPayload returns the options portion of the DHCP frame. May be zero lengthed.
func (frm Frame) OptionsPayload() []byte {
return frm.buf[:optionsOffset]
}
func (frm FrameV4) Hardware() (Type, Len, Ops uint8) {
func (frm Frame) Op() Op { return Op(frm.buf[0]) }
func (frm Frame) SetOp(op Op) { frm.buf[0] = byte(op) }
func (frm Frame) Hardware() (Type, Len, Ops uint8) {
return frm.buf[1], frm.buf[2], frm.buf[3]
}
func (frm FrameV4) SetHardware(Type, Len, Ops uint8) {
func (frm Frame) SetHardware(Type, Len, Ops uint8) {
frm.buf[1], frm.buf[2], frm.buf[3] = Type, Len, Ops
}
func (frm FrameV4) XID() uint32 {
return binary.BigEndian.Uint32(frm.buf[4:8])
}
func (frm Frame) XID() uint32 { return binary.BigEndian.Uint32(frm.buf[4:8]) }
func (frm Frame) SetXID(xid uint32) { binary.BigEndian.PutUint32(frm.buf[4:8], xid) }
func (frm FrameV4) Secs() uint16 {
return binary.BigEndian.Uint16(frm.buf[8:10])
}
func (frm Frame) Secs() uint16 { return binary.BigEndian.Uint16(frm.buf[8:10]) }
func (frm Frame) SetSecs(secs uint16) { binary.BigEndian.PutUint16(frm.buf[8:10], secs) }
func (frm FrameV4) Flags() uint16 {
return binary.BigEndian.Uint16(frm.buf[10:12])
}
func (frm Frame) Flags() Flags { return Flags(binary.BigEndian.Uint16(frm.buf[10:12])) }
func (frm Frame) SetFlags(flags Flags) { binary.BigEndian.PutUint16(frm.buf[10:12], uint16(flags)) }
// CIAddr is the client IP address. If the client has not obtained an IP
// address yet, this field is set to 0.
func (frm FrameV4) CIAddr() *[4]byte {
func (frm Frame) CIAddr() *[4]byte {
return (*[4]byte)(frm.buf[12:16])
}
// YIAddr is the IP address offered by the server to the client.
func (frm FrameV4) YIAddr() *[4]byte {
func (frm Frame) YIAddr() *[4]byte {
return (*[4]byte)(frm.buf[16:20])
}
// SIAddr is the IP address of the next server to use in bootstrap. This
// field is used in DHCPOFFER and DHCPACK messages.
func (frm FrameV4) SIAddr() *[4]byte {
func (frm Frame) SIAddr() *[4]byte {
return (*[4]byte)(frm.buf[20:24])
}
// GIAddr is the gateway IP address.
func (frm FrameV4) GIAddr() *[4]byte {
func (frm Frame) GIAddr() *[4]byte {
return (*[4]byte)(frm.buf[24:28])
}
// CHAddrAs6 returns [FrameV4.CHAddr] but limited to first 6 bytes.
func (frm FrameV4) CHAddrAs6() *[6]byte {
// CHAddrAs6 returns [Frame.CHAddr] but limited to first 6 bytes.
func (frm Frame) CHAddrAs6() *[6]byte {
return (*[6]byte)(frm.buf[28 : 28+6])
}
// CHAddr is the client hardware address. Can be up to 16 bytes in length but
// is usually 6 bytes for Ethernet.
func (frm FrameV4) CHAddr() *[16]byte {
func (frm Frame) CHAddr() *[16]byte {
return (*[16]byte)(frm.buf[28:44])
}
func (frm FrameV4) MagicCookie() uint32 {
return binary.BigEndian.Uint32(frm.buf[magicCookieOffset:])
func (frm Frame) MagicCookie() uint32 { return binary.BigEndian.Uint32(frm.buf[magicCookieOffset:]) }
func (frm Frame) SetMagicCookie(cookie uint32) {
binary.BigEndian.PutUint32(frm.buf[magicCookieOffset:], cookie)
}
// ClearHeader zeros out the header contents.
func (frm FrameV4) ClearHeader() {
for i := range frm.buf[:sizeHeader] {
func (frm Frame) ClearHeader() {
for i := range frm.buf[:optionsOffset] {
frm.buf[i] = 0
}
}
func (frm FrameV4) ForEachOption(fn func(opt Option) error) error {
func (frm Frame) ForEachOption(fn func(op OptNum, data []byte) error) error {
if fn == nil {
return errors.New("nil function to parse DHCP")
}
@@ -126,7 +131,7 @@ func (frm FrameV4) ForEachOption(fn func(opt Option) error) error {
}
optlen := frm.buf[ptr+1]
optionData := frm.buf[ptr+2 : ptr+2+int(optlen)]
if err := fn(Option{optnum, optionData}); err != nil {
if err := fn(optnum, optionData); err != nil {
return err
}
ptr += int(optlen) + 2
lneto/dhcp/stringers.go → lneto/dhcpv4/stringers.go
+2 -2
View File
@@ -1,6 +1,6 @@
// Code generated by "stringer -type=OptNum,Op,MessageType,ClientState -linecomment -output stringers.go"; DO NOT EDIT.
package dhcp
package dhcpv4
import "strconv"
@@ -111,7 +111,7 @@ func _() {
_ = x[MsgRequest-3]
_ = x[MsgDecline-4]
_ = x[MsgAck-5]
_ = x[MsgNak-6]
_ = x[MsgNack-6]
_ = x[MsgRelease-7]
_ = x[MsgInform-8]
}
lneto/frames.go
+6
View File
@@ -8,6 +8,7 @@ import (
)
// NewEthFrame returns a EthFrame with data set to buf.
// An error is returned if the buffer size is smaller than 14.
// Users should still call [EthFrame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewEthFrame(buf []byte) (EthFrame, error) {
@@ -18,6 +19,7 @@ func NewEthFrame(buf []byte) (EthFrame, error) {
}
// NewARPFrame returns a ARPFrame with data set to buf.
// An error is returned if the buffer size is smaller than 28 (IPv4 min size).
// Users should still call [ARPFrame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewARPFrame(buf []byte) (ARPFrame, error) {
@@ -28,6 +30,7 @@ func NewARPFrame(buf []byte) (ARPFrame, error) {
}
// NewIPv4Frame returns a new IPv4Frame with data set to buf.
// An error is returned if the buffer size is smaller than 20.
// Users should still call [IPv4Frame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewIPv4Frame(buf []byte) (IPv4Frame, error) {
@@ -38,6 +41,7 @@ func NewIPv4Frame(buf []byte) (IPv4Frame, error) {
}
// NewIPv6Frame returns a new IPv6Frame with data set to buf.
// An error is returned if the buffer size is smaller than 40.
// Users should still call [IPv6Frame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewIPv6Frame(buf []byte) (IPv6Frame, error) {
@@ -48,6 +52,7 @@ func NewIPv6Frame(buf []byte) (IPv6Frame, error) {
}
// NewTCPFrame returns a new TCPFrame with data set to buf.
// An error is returned if the buffer size is smaller than 20.
// Users should still call [TCPFrame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewTCPFrame(buf []byte) (TCPFrame, error) {
@@ -58,6 +63,7 @@ func NewTCPFrame(buf []byte) (TCPFrame, error) {
}
// NewUDPFrame returns a new UDPFrame with data set to buf.
// An error is returned if the buffer size is smaller than 8.
// Users should still call [UDPFrame.ValidateSize] before working
// with payload/options of frames to avoid panics.
func NewUDPFrame(buf []byte) (UDPFrame, error) {
lneto/ntp/client.go
+10 -5
View File
@@ -32,12 +32,13 @@ type Client struct {
t [4]Timestamp
// org Timestamp
// rec Timestamp
xmt Timestamp
state state
_sysprec int8
xmt Timestamp
state state
serverStratum Stratum
_sysprec int8
}
func (c *Client) Write(payload []byte) (int, error) {
func (c *Client) Send(payload []byte) (int, error) {
if c.isDone() {
return 0, io.EOF
}
@@ -71,7 +72,7 @@ func (c *Client) Write(payload []byte) (int, error) {
return SizeHeader, nil
}
func (c *Client) read(payload []byte) error {
func (c *Client) Read(payload []byte) error {
if c.isDone() {
return io.EOF
}
@@ -91,6 +92,7 @@ func (c *Client) read(payload []byte) error {
t[1] = frm.ReceiveTime()
t[2] = tstx
t[3] = c.unsyncTimestamp(c.now())
c.serverStratum = frm.Stratum()
c.state = stateDone
case stateAwait2:
c.state = stateAwait2
@@ -125,6 +127,9 @@ func (c *Client) Now() time.Time {
return c.now().Add(c.Offset())
}
// ServerStratum returns the stratum of the server client synchronized with.
func (c *Client) ServerStratum() Stratum { return c.serverStratum }
// Offset returns the
func (c *Client) Offset() time.Duration {
if c.isDone() {
lneto/ntp/definitions.go
+30 -5
View File
@@ -1,5 +1,8 @@
package ntp
// LeapIndicator represents the leap second indicator.
// It indicates whether there is no warning, an extra second (61 seconds in the last minute),
// or a missing second (59 seconds in the last minute).
type LeapIndicator uint8
const (
@@ -8,20 +11,42 @@ const (
LeapLastMinute59 // last minute 59
)
// Stratum represents the stratum level of the NTP server.
type Stratum uint8
const (
// If the Stratum field is 0, which implies unspecified or invalid, the
// Reference Identifier field can be used to convey messages useful for
// status reporting and access control. These are called Kiss-o'-Death
// (KoD) packets and the ASCII messages they convey are called kiss codes.
StratumUnspecified = 0
StratumPrimary = 1
StratumUnsync = 16
StratumUnspecified Stratum = 0 // unspecified
StratumPrimary Stratum = 1 // primary
StratumUnsync Stratum = 16 // unsynchronized
)
func IsStratumSecondary(stratum uint8) bool {
return stratum > 1 && stratum < 16
// String returns a human readable representation of the Stratum.
func (s Stratum) String() string {
switch s {
case 0:
return "unspecified"
case 1:
return "primary"
case 16:
return "unsynchronized"
}
if s < 16 {
return "secondary"
}
return "invalid"
}
func (s Stratum) IsSecondary() bool {
return s > 1 && s < 16
}
// Mode represents the mode of the NTP message.
// It can be undefined, symmetric active, symmetric passive, client, server, broadcast,
// NTP control message, or private use.
type Mode uint8
const (
lneto/ntp/ntp.go
+2 -2
View File
@@ -53,8 +53,8 @@ func (frm Frame) SetFlags(mode Mode, version uint8, lp LeapIndicator) {
frm.buf[0] = b
}
func (frm Frame) Stratum() uint8 { return frm.buf[1] }
func (frm Frame) SetStratum(stratum uint8) { frm.buf[1] = stratum }
func (frm Frame) Stratum() Stratum { return Stratum(frm.buf[1]) }
func (frm Frame) SetStratum(stratum Stratum) { frm.buf[1] = byte(stratum) }
// Poll is 8-bit signed integer representing the maximum interval between
// successive messages, in log2 seconds. Suggested default limits for