soypat/lneto
1
0
Fork 0
mirror of https://github.com/soypat/lneto.git synced 2026-08-22 07:29:04 +00:00
Code Issues Packages Projects Releases 1 Wiki Activity

dhcp working!

Browse Source
This commit is contained in:
soypat
2025-07-09 16:54:48 -03:00
parent 9c0e250cf6
commit 489e9951fa
10 changed files with 228 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files
dhcpv4/client.go
+25 -22
View File
@@ -19,6 +19,7 @@ type Client struct {
hostname []byte
dns [][4]byte
svIPtos ipv4.ToS
tRenew uint32
tRebind uint32
tIPLease uint32
@@ -73,26 +74,16 @@ func (c *Client) setIP(b []byte, frameOffset int) {
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)
// Match server ToS since some routers drop DHCP requests if no ToS set apparently?
ifrm.SetToS(c.svIPtos)
}
src := ifrm.SourceAddr()
for i := range src {
src[i] = 0
}
dst := ifrm.DestinationAddr()[:]
if c.svip == ([4]byte{}) {
for i := range dst {
dst[i] = 255
}
} else {
copy(dst, c.svip[:])
for i := range dst {
dst[i] = 255
}
}
@@ -103,6 +94,8 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
return 0, nil // No offer received yet.
} else if c.state == StateBound {
return 0, nil // Done!
} else if c.state == StateRequesting {
return 0, nil // Currently awaiting ACK.
}
dst := carrierFrame[frameOffset:]
frm, err := NewFrame(dst)
@@ -149,7 +142,7 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
nextState = StateRequesting
default:
return 0, errors.New("unhandled state")
return 0, errors.New("unhandled state" + c.state.String())
}
n, _ := EncodeOption(opts[numOpts:], OptClientIdentifier, c.clientMAC[:]...)
numOpts += n
@@ -166,10 +159,11 @@ func (c *Client) Encapsulate(carrierFrame []byte, frameOffset int) (int, error)
c.setHeader(frm)
c.setIP(carrierFrame, frameOffset)
c.state = nextState
return optionsOffset + numOpts, nil
return OptionsOffset + numOpts, nil
}
func (c *Client) Demux(carrierData []byte, frameOffset int) error {
fmt.Println("DEMUX DHCP")
if c.isClosed() {
return net.ErrClosed
}
@@ -212,13 +206,17 @@ func (c *Client) Demux(carrierData []byte, frameOffset int) error {
default:
return fmt.Errorf("dcpv4 unexpected state in recv %s", c.state.String())
}
if frameOffset > 28 && c.svIPtos == 0 {
ifrm, _ := ipv4.NewFrame(carrierData)
c.svIPtos = ifrm.ToS()
}
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 {
frm.ForEachOption(func(_ int, opt OptNum, data []byte) error {
if len(data) == 1 {
*ptrMsgType = data[0]
return io.EOF
@@ -229,7 +227,7 @@ func (c *Client) getMessageType(frm Frame) MessageType {
}
func (c *Client) setOptions(frm Frame) error {
return frm.ForEachOption(func(opt OptNum, data []byte) error {
err := frm.ForEachOption(func(_ int, opt OptNum, data []byte) error {
switch opt {
case OptRenewTimeValue:
c.tRenew = maybeU32(data)
@@ -237,7 +235,6 @@ func (c *Client) setOptions(frm Frame) error {
c.tIPLease = maybeU32(data)
case OptRebindingTimeValue:
c.tRebind = maybeU32(data)
case OptServerIdentification:
c.svip = maybe4byte(data)
case OptRouter:
@@ -261,6 +258,7 @@ func (c *Client) setOptions(frm Frame) error {
}
return nil
})
return err
}
func (c *Client) isClosed() bool { return c.state == 0 || c.currentXID == 0 }
@@ -272,16 +270,21 @@ func (c *Client) setHeader(frm Frame) {
frm.SetHardware(1, 6, 0)
frm.SetSecs(1)
if c.state.HasIP() {
copy(frm.CIAddr()[:], c.offer[:])
*frm.CIAddr() = c.offer
}
if c.state == StateInit {
siaddr := frm.SIAddr()[:]
for i := range siaddr {
siaddr[i] = 255
}
} else {
if c.siip == [4]byte{} {
*frm.SIAddr() = c.svip
} else {
*frm.SIAddr() = c.siip
}
}
copy(frm.YIAddr()[:], c.offer[:])
*frm.YIAddr() = c.offer
copy(frm.CHAddrAs6()[:], c.clientMAC[:])
frm.SetMagicCookie(MagicCookie)
}
dhcpv4/dhcp_test.go
+27 -13
View File
@@ -98,13 +98,18 @@ func TestExample(t *testing.T) {
Hostname: clientHostname,
})
buf := make([]byte, 2048)
buf2 := make([]byte, len(buf))
n, err := cl.Encapsulate(buf, 0)
if err != nil {
t.Fatal(err)
} else if n <= 0 {
t.Fatal("no data sent out by client after starting request")
}
n, err = cl.Encapsulate(buf2, 0)
if err != nil {
t.Error("client encaps double tap after discover:", err)
}
// Fabricate server OFFER response.
dfrm, _ := NewFrame(buf)
dfrm.ClearHeader()
dfrm.SetOp(OpReply)
@@ -116,27 +121,36 @@ func TestExample(t *testing.T) {
copy(dfrm.CHAddr()[:], clientHwaddr[:])
dfrm.SetMagicCookie(MagicCookie)
ntot := 0
nopt, _ := EncodeOption(buf[optionsOffset+ntot:], OptMessageType, byte(MsgOffer))
nopt, _ := EncodeOption(buf[OptionsOffset+ntot:], OptMessageType, byte(MsgOffer))
ntot += nopt
nopt, _ = EncodeOption(buf[optionsOffset+ntot:], OptServerIdentification, serverIP[:]...)
nopt, _ = EncodeOption(buf[OptionsOffset+ntot:], OptServerIdentification, serverIP[:]...)
ntot += nopt
nopt, _ = EncodeOption32(buf[optionsOffset+ntot:], OptServerIdentification, offerLease)
nopt, _ = EncodeOption32(buf[OptionsOffset+ntot:], OptServerIdentification, offerLease)
ntot += nopt
nopt, _ = EncodeOption(buf[optionsOffset+ntot:], OptSubnetMask, subnetMask[:]...)
nopt, _ = EncodeOption(buf[OptionsOffset+ntot:], OptSubnetMask, subnetMask[:]...)
ntot += nopt
nopt, _ = EncodeOption(buf[optionsOffset+ntot:], OptRouter, routerAddr[:]...)
nopt, _ = EncodeOption(buf[OptionsOffset+ntot:], OptRouter, routerAddr[:]...)
ntot += nopt
nopt, _ = EncodeOption(buf[optionsOffset+ntot:], OptDNSServers, dnsAddr[:]...)
nopt, _ = EncodeOption(buf[OptionsOffset+ntot:], OptDNSServers, dnsAddr[:]...)
ntot += nopt
nopt, _ = EncodeOption(buf[optionsOffset+ntot:], OptEnd, dnsAddr[:]...)
nopt, _ = EncodeOption(buf[OptionsOffset+ntot:], OptEnd, dnsAddr[:]...)
ntot += nopt
err = cl.Demux(buf[:optionsOffset+ntot], 0)
err = cl.Demux(buf[:OptionsOffset+ntot], 0)
if err != nil {
t.Fatal(err)
}
// frame := buf[:optionsOffset]
// frame = AppendOption(frame, OptMessageType, byte(MsgOffer))
// frame = AppendOption(frame, OptServerIdentification, serverIP[:]...)
// frame = AppendOption(frame, OptIPAddressLeaseTime, serverIP[:]...)
n, err = cl.Encapsulate(buf[:], 0)
if err != nil {
t.Fatal(err)
} else if n <= 0 {
t.Fatal("no data written from client in response to offer")
}
n, err = cl.Encapsulate(buf[:], 0)
if err != nil {
t.Error("encapsulate double tap after request:", err)
} else if n > 0 {
t.Error("encapsulate double tap got data!", n)
}
}
dhcpv4/frame.go
+11 -7
View File
@@ -17,7 +17,7 @@ const (
// Expected Magic Cookie value.
MagicCookie uint32 = 0x63825363
// DHCP Options offset measured from the start of the UDP payload.
optionsOffset = magicCookieOffset + 4
OptionsOffset = magicCookieOffset + 4
DefaultClientPort = 68
DefaultServerPort = 67
@@ -26,12 +26,16 @@ const (
// 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 {
if len(buf) < OptionsOffset {
return Frame{}, errSmallFrame
}
return Frame{buf: buf}, nil
}
func PayloadIsDHCPv4(payload []byte) bool {
return len(payload) >= OptionsOffset && binary.BigEndian.Uint32(payload[magicCookieOffset:]) == MagicCookie
}
// Frame encapsulates the raw data of a DHCP packet
// and provides methods for manipulating, validating and
// retrieving fields and payload data. See [RFC2131].
@@ -43,7 +47,7 @@ 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]) }
@@ -111,16 +115,16 @@ func (frm Frame) SetMagicCookie(cookie uint32) {
// ClearHeader zeros out the header contents.
func (frm Frame) ClearHeader() {
for i := range frm.buf[:optionsOffset] {
for i := range frm.buf[:OptionsOffset] {
frm.buf[i] = 0
}
}
// 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 {
func (frm Frame) ForEachOption(fn func(off int, op OptNum, data []byte) error) error {
// Parse DHCP options.
ptr := optionsOffset
ptr := OptionsOffset
if ptr > len(frm.buf) {
return errSmallFrame
} else if len(frm.buf[ptr:]) == 0 {
@@ -141,7 +145,7 @@ func (frm Frame) ForEachOption(fn func(op OptNum, data []byte) error) error {
optlen := frm.buf[ptr+1]
if callback {
optionData := frm.buf[ptr+2 : ptr+2+int(optlen)]
if err := fn(optnum, optionData); err != nil {
if err := fn(ptr, optnum, optionData); err != nil {
return err
}
}
dhcpv4/server.go
+2 -2
View File
@@ -77,7 +77,7 @@ func (sv *Server) Demux(carrierData []byte, frameOffset int) error {
var reqlist []byte
var reqAddr []byte
var hostname []byte
err = dfrm.ForEachOption(func(op OptNum, data []byte) error {
err = dfrm.ForEachOption(func(off int, op OptNum, data []byte) error {
switch op {
case OptMessageType:
if len(data) == 1 {
@@ -231,7 +231,7 @@ func (sv *Server) Encapsulate(carrierData []byte, frameOffset int) (int, error)
// Set server state.
sv.hosts[clientID] = client
sv.pending--
return optionsOffset + nopt, nil
return OptionsOffset + nopt, nil
}
func (sv *Server) getClient(clientID [36]byte) (serverEntry, bool) {