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add dhcp failing test

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This commit is contained in:
soypat
2025-06-17 02:07:11 -03:00
parent 47eae76dcf
commit 2133966a16
17 changed files with 596 additions and 195 deletions
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dhcpv4/client.go
+28 -3
View File
@@ -10,6 +10,7 @@ import (
"net"
"github.com/soypat/lneto"
"github.com/soypat/lneto/ipv4"
)
type Client struct {
@@ -63,6 +64,24 @@ func (c *Client) Protocol() uint64 { return uint64(lneto.IPProtoUDP) }
func (c *Client) LocalPort() uint16 { return DefaultClientPort }
func (c *Client) ConnectionID() *uint64 { return &c.connID }
func (c *Client) setIP(b []byte, frameOffset int) {
if frameOffset < 28 {
return // Not an IP/UDP frame.
}
ifrm, _ := ipv4.NewFrame(b)
ifrm.SetID((uint16(c.currentXID) ^ uint16(c.currentXID>>16)) + uint16(c.state))
if c.state > StateInit {
// TODO(soypat): Document why disabling ToS used by DHCP server may cause Request to fail.
// Apparently server sets ToS=192. Uncommenting this line causes DHCP to fail on my setup.
// If left fixed at 192, DHCP does not work.
// If left fixed at 0, DHCP does not work.
// Apparently ToS is a function of which state of DHCP one is in. Not sure why code below works.
// Note: Not exactly needed for all servers.
const ecnmask = 0b1100_0000
ifrm.SetToS(ecnmask)
}
}
func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error) {
if c.isClosed() {
return 0, net.ErrClosed
@@ -98,6 +117,9 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
nextState = StateSelecting
case StateSelecting:
if c.offer == ([4]byte{}) {
return 0, nil // Offer not yet received.
}
// Send out request, we know we've received an offer by now.
optBuf = AppendOption(optBuf, OptMessageType, byte(MsgRequest))
optBuf = AppendOption(optBuf, OptRequestedIPaddress, c.offer[:]...)
@@ -108,8 +130,7 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
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 = AppendOptionString(optBuf, OptHostName, c.reqHostname)
}
optBuf = append(optBuf, 0xff) // End mark.
options := frm.OptionsPayload()
@@ -118,6 +139,7 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
}
c.setHeader(frm)
n := copy(options, optBuf)
c.setIP(carrierFrame, frameOffset)
c.state = nextState
return optionsOffset + n, nil
}
@@ -155,6 +177,7 @@ func (c *Client) Demux(carrierData []byte, frameOffset int) error {
// Lock in on this offer.
c.gateway = *frm.GIAddr()
c.offer = *frm.YIAddr()
c.svip = *frm.SIAddr()
}
case StateRequesting:
@@ -223,7 +246,9 @@ func (c *Client) setHeader(frm Frame) {
frm.SetXID(c.currentXID)
frm.SetHardware(1, 6, 0)
frm.SetSecs(1)
// copy(frm.CIAddr()[:], c.offer[:])
if c.state == StateBound {
// copy(frm.CIAddr()[:], c.offer[:])
}
copy(frm.SIAddr()[:], c.svip[:])
copy(frm.YIAddr()[:], c.offer[:])
copy(frm.CHAddrAs6()[:], c.clientMAC[:])
dhcpv4/definitions.go
+6
View File
@@ -2,6 +2,7 @@ package dhcpv4
import (
"errors"
"unsafe"
)
//go:generate stringer -type=OptNum,Op,MessageType,ClientState -linecomment -output stringers.go
@@ -38,6 +39,11 @@ func AppendOption(dst []byte, opt OptNum, data ...byte) []byte {
return dst
}
func AppendOptionString(dst []byte, opt OptNum, data string) []byte {
bdata := unsafe.Slice(unsafe.StringData(data), len(data))
return AppendOption(dst, opt, bdata...)
}
func EncodeOption(dst []byte, opt OptNum, data ...byte) (int, error) {
if len(data) > 255 {
return 0, errors.New("DHCPv4 option data too long (>255)")
dhcpv4/dhcp_test.go
+66
View File
@@ -0,0 +1,66 @@
package dhcpv4
import (
"testing"
)
func TestClientServer(t *testing.T) {
svAddr := [4]byte{192, 168, 1, 1}
clAddr := svAddr
clAddr[3]++
var sv Server
var cl Client
err := cl.BeginRequest(123, RequestConfig{
RequestedAddr: clAddr,
ClientHardwareAddr: [6]byte{1, 2, 3, 4, 5, 6},
Hostname: "lneto",
})
if err != nil {
t.Fatal(err)
}
assertClState := func(state ClientState) {
t.Helper()
if state != cl.State() {
t.Errorf("want client state %s, got %s", state.String(), cl.State().String())
}
}
sv.Reset(svAddr, DefaultServerPort)
// CLIENT DISCOVER.
assertClState(StateInit)
var buf [1024]byte
n, err := cl.Encapsulate(buf[:], 0)
if err != nil {
t.Fatal(err)
} else if n == 0 {
t.Fatal("no data exchanged")
}
assertClState(StateSelecting)
err = sv.Demux(buf[:n], 0)
if err != nil {
t.Fatal(err)
}
// SERVER REPLY OFFER
n, err = sv.Encapsulate(buf[:], 0)
if err != nil {
t.Fatal(err)
} else if n == 0 {
t.Fatal("no data exchanged")
}
err = cl.Demux(buf[:n], 0)
if err != nil {
t.Fatal(err)
}
assertClState(StateRequesting)
// CLIENT SEND OUT ACK.
n, err = cl.Encapsulate(buf[:], 0)
if err != nil {
t.Fatal(err)
} else if n == 0 {
t.Fatal("no data exchanged")
}
err = sv.Demux(buf[:n], 0)
if err != nil {
t.Fatal(err)
}
}
dhcpv4/frame.go
+38 -11
View File
@@ -3,6 +3,8 @@ package dhcpv4
import (
"encoding/binary"
"errors"
"github.com/soypat/lneto"
)
const (
@@ -25,7 +27,7 @@ const (
// 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 Frame{}, errSmallFrame
}
return Frame{buf: buf}, nil
}
@@ -41,7 +43,7 @@ type Frame struct {
// OptionsPayload returns the options portion of the DHCP frame. May be zero lengthed.
func (frm Frame) OptionsPayload() []byte {
return frm.buf[:optionsOffset]
return frm.buf[optionsOffset:]
}
func (frm Frame) Op() Op { return Op(frm.buf[0]) }
@@ -97,7 +99,10 @@ func (frm Frame) CHAddr() *[16]byte {
return (*[16]byte)(frm.buf[28:44])
}
// MagicCookie returns the magic cookie of the header. Expect this to always be [MagicCookie].
func (frm Frame) MagicCookie() uint32 { return binary.BigEndian.Uint32(frm.buf[magicCookieOffset:]) }
// SetMagicCookie sets the MagicCookie. Call this with [MagicCookie] to create a valid DHCP header.
func (frm Frame) SetMagicCookie(cookie uint32) {
binary.BigEndian.PutUint32(frm.buf[magicCookieOffset:], cookie)
}
@@ -109,18 +114,20 @@ func (frm Frame) ClearHeader() {
}
}
// ForEachOption iterates over all DHCPv4 options returning an error on a malformed option or when user provided callback returns an error.
// If the user provided callback is nil then only option buffer validation is performed.
func (frm Frame) ForEachOption(fn func(op OptNum, data []byte) error) error {
if fn == nil {
return errors.New("nil function to parse DHCP")
}
// Parse DHCP options.
ptr := optionsOffset
if ptr >= len(frm.buf) {
return errors.New("short payload to parse DHCP options")
if ptr > len(frm.buf) {
return errSmallFrame
} else if len(frm.buf[ptr:]) == 0 {
return errNoOptions
}
callback := fn != nil
for ptr+1 < len(frm.buf) {
if int(frm.buf[ptr+1]) >= len(frm.buf) {
return errors.New("DHCP option length exceeds payload")
return errDHCPBadOption
}
optnum := OptNum(frm.buf[ptr])
if optnum == 0xff {
@@ -130,11 +137,31 @@ func (frm Frame) ForEachOption(fn func(op OptNum, data []byte) error) error {
continue
}
optlen := frm.buf[ptr+1]
optionData := frm.buf[ptr+2 : ptr+2+int(optlen)]
if err := fn(optnum, optionData); err != nil {
return err
if callback {
optionData := frm.buf[ptr+2 : ptr+2+int(optlen)]
if err := fn(optnum, optionData); err != nil {
return err
}
}
ptr += int(optlen) + 2
}
return nil
}
//
// Validation API.
//
var (
errSmallFrame = errors.New("DHCPv4: frame size <240")
errDHCPBadOption = errors.New("DHCPv4: opt length exceeds payload")
errNoOptions = errors.New("DHCPv4: no options")
errOptionNotFit = errors.New("DHCPv4: options dont fit")
)
func (frm Frame) ValidateSize(vld *lneto.Validator) {
err := frm.ForEachOption(nil) // Does all necessary validation.
if err != nil {
vld.AddError(errDHCPBadOption)
}
}
dhcpv4/server.go
+239
View File
@@ -0,0 +1,239 @@
package dhcpv4
import (
"encoding/binary"
"errors"
"fmt"
"net/netip"
"github.com/soypat/lneto"
"github.com/soypat/lneto/internal"
)
type Server struct {
connID uint64
nextAddr netip.Addr
prefix netip.Prefix
hosts map[[36]byte]serverEntry
vld lneto.Validator
pending int
port uint16
siaddr [4]byte
gwaddr [4]byte
}
type serverEntry struct {
hostname string
xid uint32
port uint16
addr [4]byte
requestlist [10]byte
hwaddr [6]byte
clientIdlen uint8
// Possible states:
// - 0: No entry/uninitialized
// - Init: Server received discover, pending Offer sent out.
// - Selecting: Server sent out offer, request not received.
// - Requesting: Request received, pending Ack sent out.
// - Bound: Request sent out, no more pending data to be sent.
state ClientState
}
func (sv *Server) Reset(serverAddr [4]byte, port uint16) {
*sv = Server{
connID: sv.connID + 1,
siaddr: serverAddr,
port: port,
hosts: sv.hosts,
nextAddr: netip.AddrFrom4(serverAddr),
}
if sv.hosts == nil {
sv.hosts = make(map[[36]byte]serverEntry)
} else {
for k := range sv.hosts {
delete(sv.hosts, k)
}
}
}
func (sv *Server) ConnectionID() *uint64 { return &sv.connID }
func (sv *Server) Protocol() uint64 { return uint64(lneto.IPProtoUDP) }
func (sv *Server) Port() uint16 { return sv.port }
func (sv *Server) Demux(carrierData []byte, frameOffset int) error {
isIPLayer := frameOffset >= 28
dhcpData := carrierData[frameOffset:]
dfrm, err := NewFrame(dhcpData)
if err != nil {
return err
}
dfrm.ValidateSize(&sv.vld)
if sv.vld.HasError() {
return sv.vld.ErrPop()
}
var msgType MessageType
var clientID []byte
var reqlist []byte
var reqAddr []byte
var hostname []byte
err = dfrm.ForEachOption(func(op OptNum, data []byte) error {
switch op {
case OptMessageType:
if len(data) == 1 {
msgType = MessageType(data[0])
}
case OptHostName:
if len(data) <= 36 {
hostname = data
}
case OptClientIdentifier:
if len(data) <= 36 {
clientID = data
}
case OptParameterRequestList:
if len(data) > 36 {
return errors.New("too many request options")
}
reqlist = data
case OptRequestedIPaddress:
if len(data) == 4 {
reqAddr = data
}
}
return nil
})
var clientIDRaw [36]byte
var client serverEntry
var clientExists bool
if len(clientID) == 0 {
client, clientIDRaw, clientExists = sv.getClientByIP(*dfrm.CIAddr())
} else {
copy(clientIDRaw[:], clientID)
client, clientExists = sv.getClient(clientIDRaw)
}
switch msgType {
case MsgDiscover:
if clientExists {
err = errors.New("DHCP Discover on initialized client")
break
}
if len(reqAddr) == 4 {
println("requested", reqAddr[0], reqAddr[1], reqAddr[2], reqAddr[3])
}
sv.nextAddr = sv.nextAddr.Next()
copy(client.requestlist[:], reqlist)
client.addr = sv.nextAddr.As4()
client.state = StateInit
client.hostname = string(hostname)
client.xid = dfrm.XID()
client.hwaddr = *dfrm.CHAddrAs6()
if isIPLayer {
_, client.port, _ = getSrcIPPort(carrierData)
}
client.clientIdlen = uint8(len(clientID))
sv.pending++
case MsgRequest:
if client.state != StateSelecting && client.state != StateRequesting {
err = errors.New("DHCP request unexpected state")
break
}
client.state = StateBound
sv.pending++
default:
err = errors.New("unhandled message type")
}
if err != nil {
return fmt.Errorf("msgtype=%s client=%+v: %w", msgType.String(), client, err)
}
sv.hosts[clientIDRaw] = client
return nil
// n := copy(dfrm.OptionsPayload(), optBuf)
}
func (sv *Server) Encapsulate(carrierData []byte, frameOffset int) (int, error) {
carrierIsIP := frameOffset >= 28
dfrm, err := NewFrame(carrierData[frameOffset:])
optBuf := dfrm.OptionsPayload()[:0]
if err != nil {
return 0, err
} else if cap(optBuf) < 255 {
return 0, errOptionNotFit
}
if sv.pending == 0 {
return 0, nil // No pending outgoing frames.a
}
var client serverEntry
var clientID [36]byte
for k, v := range sv.hosts {
pending := v.state == StateInit || v.state == StateRequesting
if pending {
client = v
clientID = k
break
}
}
if client.state == 0 {
return 0, nil // Nothing to do.
}
futureState := ClientState(0)
switch client.state {
case StateInit:
futureState = StateSelecting
optBuf = AppendOption(optBuf, OptMessageType, byte(MsgOffer))
case StateRequesting:
futureState = StateBound
optBuf = AppendOption(optBuf, OptMessageType, byte(MsgAck))
*dfrm.CIAddr() = client.addr
}
dfrm.ClearHeader()
dfrm.SetOp(OpReply)
dfrm.SetHardware(1, 6, 0)
dfrm.SetXID(client.xid)
dfrm.SetSecs(0)
dfrm.SetFlags(0)
*dfrm.YIAddr() = client.addr // Offer here.
*dfrm.SIAddr() = sv.siaddr
*dfrm.GIAddr() = sv.gwaddr
copy(dfrm.CHAddrAs6()[:], client.hwaddr[:])
dfrm.SetMagicCookie(MagicCookie)
if carrierIsIP {
internal.SetIPDestinationAddr(carrierData, 0, client.addr[:])
}
client.state = futureState
// Set server state.
sv.hosts[clientID] = client
sv.pending--
return optionsOffset + len(optBuf), nil
}
func (sv *Server) getClient(clientID [36]byte) (serverEntry, bool) {
entry, ok := sv.hosts[clientID]
return entry, ok
}
func (sv *Server) getClientByIP(ip [4]byte) (serverEntry, [36]byte, bool) {
for k, v := range sv.hosts {
if v.addr == ip {
return v, k, true
}
}
return serverEntry{}, [36]byte{}, false
}
func getSrcIPPort(ipCarrier []byte) (addr []byte, port uint16, err error) {
addr, _, off, err := internal.GetIPSourceAddr(ipCarrier)
if err != nil {
return addr, port, err
} else if len(ipCarrier[off:]) < 2 {
return addr, port, errors.New("getSrcIPPort got only IP layer")
}
port = binary.BigEndian.Uint16(ipCarrier[off:]) // TCP and UDP share same port offsets.
return addr, port, nil
}