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generalize ARP to any protocol

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soypat
2024-12-24 16:17:48 -03:00
parent 8c3492b54b
commit 4476c7bae3
4 changed files with 117 additions and 32 deletions
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lneto/definitions.go
+9 -1
View File
@@ -1,6 +1,6 @@
package lneto
//go:generate stringer -type=EtherType,IPProto -linecomment -output stringers.go .
//go:generate stringer -type=EtherType,IPProto,ARPOp -linecomment -output stringers.go .
type EtherType uint16
@@ -245,3 +245,11 @@ const (
IPProtoAGGFRAG IPProto = 144 // AGGFRAG Encapsulation payload for ESP
IPProtoNSH IPProto = 145 // Network Service Header
)
// ARPOp represents the type of ARP packet, either request or reply/response.
type ARPOp uint8
const (
ARPRequest ARPOp = 1 // request
ARPReply ARPOp = 2 // reply
)
lneto/frames.go
+75 -29
View File
@@ -9,8 +9,8 @@ import (
func NewEthFrame(buf []byte) EthFrame {
return EthFrame{buf: mustBufferFrameLen(buf, sizeHeaderEthNoVLAN, "Ethernet")}
}
func NewARPv4Frame(buf []byte) ARPv4Frame {
return ARPv4Frame{buf: mustBufferFrameLen(buf, sizeHeaderARPv4, "ARPv4")}
func NewARPFrame(buf []byte) ARPFrame {
return ARPFrame{buf: mustBufferFrameLen(buf, sizeHeaderARPv4, "ARPv4")}
}
func NewIPv4Frame(buf []byte) IPv4Frame {
return IPv4Frame{buf: mustBufferFrameLen(buf, sizeHeaderIPv4, "IPv4")}
@@ -82,55 +82,84 @@ func (efrm EthFrame) IsVLAN() bool {
return efrm.EtherTypeOrSize() == EtherTypeVLAN
}
type ARPv4Frame struct {
type ARPFrame struct {
buf []byte
}
// RawData returns the underlying slice with which the frame was created.
func (afrm ARPv4Frame) RawData() []byte { return afrm.buf }
func (afrm ARPFrame) RawData() []byte { return afrm.buf }
// HardwareType specifies the network link protocol type. Example: Ethernet is 1.
func (afrm ARPv4Frame) Hardware() (Type uint16, length uint8) {
func (afrm ARPFrame) Hardware() (Type uint16, length uint8) {
Type = binary.BigEndian.Uint16(afrm.buf[0:2])
length = afrm.buf[4]
return Type, length
}
func (afrm ARPv4Frame) SetHardware(Type uint16, length uint8) {
// SetHardware sets the networl link protocol type. See [ARPFrame.SetHardware].
func (afrm ARPFrame) SetHardware(Type uint16, length uint8) {
binary.BigEndian.PutUint16(afrm.buf[0:2], Type)
afrm.buf[4] = length
}
func (afrm ARPv4Frame) Protocol() (Type uint16, length uint8) {
Type = binary.BigEndian.Uint16(afrm.buf[2:4])
// Protocol returns the internet protocol type and length. See [EtherType].
func (afrm ARPFrame) Protocol() (Type EtherType, length uint8) {
Type = EtherType(binary.BigEndian.Uint16(afrm.buf[2:4]))
length = afrm.buf[5]
return Type, length
}
func (afrm ARPv4Frame) SetProtocol(Type uint16, length uint8) {
binary.BigEndian.PutUint16(afrm.buf[2:4], Type)
// SetProtocol sets the protocol type and length fields of the ARP frame. See [ARPFrame.Protocol] and [EtherType].
func (afrm ARPFrame) SetProtocol(Type EtherType, length uint8) {
binary.BigEndian.PutUint16(afrm.buf[2:4], uint16(Type))
afrm.buf[5] = length
}
func (afrm ARPv4Frame) SetOperation(b uint8) { afrm.buf[6] = b }
// Operation returns the ARP header operation field. See [ARPOp].
func (afrm ARPFrame) Operation() ARPOp { return ARPOp(afrm.buf[6]) }
func (afrm ARPv4Frame) IsOperationRequest() bool { return afrm.buf[6] == 1 }
func (afrm ARPv4Frame) IsOperationReply() bool { return afrm.buf[6] == 2 }
// SetOperation sets the ARP header operation field. See [ARPOp].
func (afrm ARPFrame) SetOperation(b ARPOp) { afrm.buf[6] = uint8(b) }
// Sender returns the MAC (hardware) and IP (protocol) addresses of sender of ARP packet.
// In an ARP request MAC is used to indicate
// the address of the host sending the request. In an ARP reply MAC is
// Sender returns the hardware (MAC) and protocol addresses of sender of ARP packet.
// In an ARP request MAC address is used to indicate
// the address of the host sending the request. In an ARP reply MAC address is
// used to indicate the address of the host that the request was looking for.
func (afrm ARPv4Frame) Sender() (hardwareAddr *[6]byte, proto *[4]byte) {
func (afrm ARPFrame) Sender() (hardwareAddr []byte, proto []byte) {
_, hlen := afrm.Hardware()
_, ilen := afrm.Protocol()
return afrm.buf[8 : 8+hlen], afrm.buf[8+hlen : 8+hlen+ilen]
}
// Target returns the hardware (MAC) and protocol addresses of target of ARP packet.
// In an ARP request MAC target is ignored. In ARP reply MAC is used to indicate the address of host that originated request.
func (afrm ARPFrame) Target() (hardwareAddr []byte, proto []byte) {
_, hlen := afrm.Hardware()
_, ilen := afrm.Protocol()
toff := 8 + hlen + ilen
return afrm.buf[toff : toff+hlen], afrm.buf[toff+hlen : toff+hlen+ilen]
}
// Sender4 returns the IPv4 sender addresses. See [ARPFrame.Sender].
func (afrm ARPFrame) Sender4() (hardwareAddr *[6]byte, proto *[4]byte) {
return (*[6]byte)(afrm.buf[8:14]), (*[4]byte)(afrm.buf[14:18])
}
// Target returns the MAC (hardware) and IP (protocol) addresses of target of ARP packet.
// In an ARP request MAC target is ignored. In ARP reply MAC is used to indicate the address of host that originated request.
func (afrm ARPv4Frame) Target() (hardwareAddr *[6]byte, proto *[4]byte) {
// Target4 returns the IPv4 target addresses. See [ARPFrame.Sender].
func (afrm ARPFrame) Target4() (hardwareAddr *[6]byte, proto *[4]byte) {
return (*[6]byte)(afrm.buf[18:24]), (*[4]byte)(afrm.buf[24:28])
}
// Sender6 returns the IPv6 sender addresses. See [ARPFrame.Sender].
func (afrm ARPFrame) Sender16() (hardwareAddr *[6]byte, proto *[16]byte) {
return (*[6]byte)(afrm.buf[8:14]), (*[16]byte)(afrm.buf[14:30])
}
// Target6 returns the IPv6 target addresses. See [ARPFrame.Sender].
func (afrm ARPFrame) Target16() (hardwareAddr *[6]byte, proto *[16]byte) {
return (*[6]byte)(afrm.buf[30:36]), (*[16]byte)(afrm.buf[36:52])
}
type IPv4Frame struct {
buf []byte
}
@@ -138,14 +167,22 @@ type IPv4Frame struct {
// RawData returns the underlying slice with which the frame was created.
func (ifrm IPv4Frame) RawData() []byte { return ifrm.buf }
func (ifrm IPv4Frame) Version() uint8 { return ifrm.buf[0] & 0xf }
func (ifrm IPv4Frame) IHL() uint8 { return ifrm.buf[0] >> 4 }
// HeaderLength returns the length of the IPv4 header as calculated using IHL. It includes IP options.
func (ifrm IPv4Frame) HeaderLength() int {
return int(ifrm.IHL()) * 4
return int(ifrm.ihl()) * 4
}
func (ifrm IPv4Frame) ihl() uint8 {
return ifrm.buf[0] >> 4
}
// VersionAndIHL returns the version and IHL fields in the IPv4 header. Version should always be 4.
func (ifrm IPv4Frame) VersionAndIHL() (version, IHL uint8) {
v := ifrm.buf[0]
return v & 0xf, v >> 4
}
// SetVersionAndIHL sets the version and IHL fields in the IPv4 header. Version should always be 4.
func (ifrm IPv4Frame) SetVersionAndIHL(version, IHL uint8) { ifrm.buf[0] = version&0xf | IHL<<4 }
// ToS (Type of Service) contains Differential Services Code Point (DSCP) and
@@ -217,7 +254,7 @@ func (ifrm IPv4Frame) Protocol() IPProto { return IPProto(ifrm.buf[9]) }
// SetProtocol sets protocol field. See [IPv4Frame.Protocol] and [IPProto].
func (ifrm IPv4Frame) SetProtocol(proto IPProto) { ifrm.buf[9] = uint8(proto) }
// CRC returns the cyclic-redundancy check field of the IPv4 packet.
// CRC returns the cyclic-redundancy-check (checksum) field of the IPv4 header.
func (ifrm IPv4Frame) CRC() uint16 {
return binary.BigEndian.Uint16(ifrm.buf[10:12])
}
@@ -238,7 +275,7 @@ func (ifrm IPv4Frame) CalculateHeaderCRC() uint16 {
func (ifrm IPv4Frame) crcWriteTCPPseudo(crc *CRC791) {
crc.Write(ifrm.SourceAddr()[:])
crc.Write(ifrm.DestinationAddr()[:])
crc.AddUint16(ifrm.TotalLength() - 4*uint16(ifrm.IHL()))
crc.AddUint16(ifrm.TotalLength() - 4*uint16(ifrm.ihl()))
crc.AddUint16(uint16(ifrm.Protocol()))
}
@@ -258,6 +295,8 @@ func (ifrm IPv4Frame) DestinationAddr() *[4]byte {
return (*[4]byte)(ifrm.buf[16:20])
}
// Payload returns the contents of the IPv4 packet, which may be zero sized.
// Be sure to call [IPv4Frame.ValidateSize] beforehand to avoid panic.
func (ifrm IPv4Frame) Payload() []byte {
off := ifrm.HeaderLength()
l := ifrm.TotalLength()
@@ -272,6 +311,7 @@ type IPv6Frame struct {
func (i6frm IPv6Frame) RawData() []byte { return i6frm.buf }
// Payload returns the contents of the IPv6 packet, which may be zero sized.
// Be sure to call [IPv6Frame.ValidateSize] beforehand to avoid panic.
func (i6frm IPv6Frame) Payload() []byte {
pl := i6frm.PayloadLength()
return i6frm.buf[sizeHeaderIPv6 : sizeHeaderIPv6+pl]
@@ -432,7 +472,7 @@ func (tfrm TCPFrame) SetCRC(checksum uint16) {
func (tfrm TCPFrame) CalculateIPv4CRC(ifrm IPv4Frame) uint16 {
var crc CRC791
ifrm.crcWriteTCPPseudo(&crc)
expectLen := int(ifrm.TotalLength()) - 4*int(ifrm.IHL())
expectLen := int(ifrm.TotalLength()) - ifrm.HeaderLength()
if expectLen != len(tfrm.buf) {
println("unexpected TCP buffer length mismatches IPv4 header total length", expectLen, len(tfrm.buf))
}
@@ -466,6 +506,8 @@ func (tfrm TCPFrame) UrgentPtr() uint16 {
return binary.BigEndian.Uint16(tfrm.buf[18:20])
}
// Payload returns the payload content section of the TCP packet (not including TCP options).
// Be sure to call [TCPFrame.ValidateSize] beforehand to avoid panic.
func (tfrm TCPFrame) Payload() []byte {
return tfrm.buf[tfrm.HeaderLength():]
}
@@ -477,15 +519,17 @@ type UDPFrame struct {
// RawData returns the underlying slice with which the frame was created.
func (ufrm UDPFrame) RawData() []byte { return ufrm.buf }
// SourcePort identifies the sending port for the UDP packet. Must be non-zero.
func (ufrm UDPFrame) SourcePort() uint16 {
return binary.BigEndian.Uint16(ufrm.buf[0:2])
}
// SetSourcePort sets UDP source port. See [UDPFrame.SetSourcePort]
// SetSourcePort sets UDP source port. See [UDPFrame.SourcePort]
func (ufrm UDPFrame) SetSourcePort(src uint16) {
binary.BigEndian.PutUint16(ufrm.buf[0:2], src)
}
// DestinationPort identifies the receiving port for the UDP packet. Must be non-zero.
func (ufrm UDPFrame) DestinationPort() uint16 {
return binary.BigEndian.Uint16(ufrm.buf[2:4])
}
@@ -507,6 +551,7 @@ func (ufrm UDPFrame) SetLength(length uint16) {
binary.BigEndian.PutUint16(ufrm.buf[4:6], length)
}
// CRC returns the checksum field in the UDP header.
func (ufrm UDPFrame) CRC() uint16 {
return binary.BigEndian.Uint16(ufrm.buf[6:8])
}
@@ -516,7 +561,8 @@ func (ufrm UDPFrame) SetCRC(checksum uint16) {
binary.BigEndian.PutUint16(ufrm.buf[6:8], checksum)
}
// Payload returns the data part of the UDP frame.
// Payload returns the payload content section of the UDP packet.
// Be sure to call [UDPFrame.ValidateSize] beforehand to avoid panic.
func (ufrm UDPFrame) Payload() []byte {
l := ufrm.Length()
return ufrm.buf[sizeHeaderUDP:l]
lneto/stringers.go
+20 -1
View File
@@ -1,4 +1,4 @@
// Code generated by "stringer -type=EtherType,IPProto -linecomment -output stringers.go ."; DO NOT EDIT.
// Code generated by "stringer -type=EtherType,IPProto,ARPOp -linecomment -output stringers.go ."; DO NOT EDIT.
package lneto
@@ -289,3 +289,22 @@ func (i IPProto) String() string {
return "IPProto(" + strconv.FormatInt(int64(i), 10) + ")"
}
}
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[ARPRequest-1]
_ = x[ARPReply-2]
}
const _ARPOp_name = "requestreply"
var _ARPOp_index = [...]uint8{0, 7, 12}
func (i ARPOp) String() string {
i -= 1
if i >= ARPOp(len(_ARPOp_index)-1) {
return "ARPOp(" + strconv.FormatInt(int64(i+1), 10) + ")"
}
return _ARPOp_name[_ARPOp_index[i]:_ARPOp_index[i+1]]
}
lneto/validation.go
+13 -1
View File
@@ -8,11 +8,23 @@ var (
errShortIPv4 = errors.New("IPv4 total length exceeds frame")
errBadIPv4TL = errors.New("IPv4 short total length")
errShortIPv6 = errors.New("IPv6 payload length exceeds frame")
errShortARP = errors.New("bad ARP size")
errShortTCP = errors.New("TCP offset exceeds frame")
errBadTCPOff = errors.New("TCP offset invalid")
)
// ValidateSize checks the frame's size fields and compares with the actual buffer
// the frame. It returns a non-nil error on finding an inconsistency.
func (afrm ARPFrame) ValidateSize() error {
_, hlen := afrm.Hardware()
_, ilen := afrm.Protocol()
minLen := 8 + 2*(hlen+ilen)
if len(afrm.buf) < int(minLen) {
return errShortARP
}
return nil
}
// ValidateSize checks the frame's size fields and compares with the actual buffer
// the frame. It returns a non-nil error on finding an inconsistency.
func (ufrm UDPFrame) ValidateSize() error {