soypat/lneto
1
0
Fork 0
mirror of https://github.com/soypat/lneto.git synced 2026-09-01 12:29:05 +00:00
Code Issues Packages Projects Releases 1 Wiki Activity

Tcp rst handling (#40)

Browse Source 
* claude suggests a way forward

* add timing to capture printer

* add pcap.Flags

* fix ICMP CRC calculation and add test

* bugfix: still send data on half-close state(close-wait)

* fix pcap test
This commit is contained in:
Pat Whittingslow
2026-02-23 13:50:13 +01:00
committed by GitHub
parent 08423d0dba
commit 7d323aae19
10 changed files with 386 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
internal/ltesto/ltesto.go
+68
View File
@@ -8,6 +8,7 @@ import (
"github.com/soypat/lneto"
"github.com/soypat/lneto/ethernet"
"github.com/soypat/lneto/ipv4"
"github.com/soypat/lneto/ipv4/icmpv4"
"github.com/soypat/lneto/tcp"
)
@@ -160,6 +161,73 @@ func (gen *PacketGen) AppendRandomIPv4TCPPacket(dst []byte, rng *rand.Rand, seg
return dst
}
// ICMPEchoConfig configures an ICMP echo request packet.
type ICMPEchoConfig struct {
Identifier uint16
SequenceNumber uint16
Payload []byte
}
// AppendIPv4ICMPEcho builds and appends a complete Ethernet+IPv4+ICMP echo request packet to dst.
// The packet has valid Ethernet, IPv4, and ICMP checksums.
func (gen *PacketGen) AppendIPv4ICMPEcho(dst []byte, cfg ICMPEchoConfig) []byte {
const icmpHdrLen = 8
ethsize := sizeHeaderEthNoVLAN
if gen.EnableVLAN {
ethsize += 4
}
totalPayload := icmpHdrLen + len(cfg.Payload)
off := len(dst)
dst = append(dst, make([]byte, ethsize+sizeHeaderIPv4+totalPayload)...)
pkt := dst[off:]
// Ethernet header.
efrm, err := ethernet.NewFrame(pkt)
if err != nil {
panic(err)
}
*efrm.DestinationHardwareAddr() = gen.DstMAC
*efrm.SourceHardwareAddr() = gen.SrcMAC
efrm.SetEtherType(ethernet.TypeIPv4)
// IPv4 header.
ethernetPayload := efrm.Payload()
ifrm, err := ipv4.NewFrame(ethernetPayload)
if err != nil {
panic(err)
}
ifrm.SetVersionAndIHL(4, 5)
ifrm.SetTotalLength(uint16(sizeHeaderIPv4 + totalPayload))
ifrm.SetID(0)
ifrm.SetFlags(0)
ifrm.SetTTL(64)
ifrm.SetProtocol(lneto.IPProtoICMP)
*ifrm.SourceAddr() = gen.SrcIPv4
*ifrm.DestinationAddr() = gen.DstIPv4
ifrm.SetCRC(0)
ifrm.SetCRC(ifrm.CalculateHeaderCRC())
// ICMP echo request.
icmpData := ifrm.Payload()
icmpFrm, err := icmpv4.NewFrame(icmpData)
if err != nil {
panic(err)
}
icmpFrm.SetType(icmpv4.TypeEcho)
icmpFrm.SetCode(0)
echo := icmpv4.FrameEcho{Frame: icmpFrm}
echo.SetIdentifier(cfg.Identifier)
echo.SetSequenceNumber(cfg.SequenceNumber)
copy(echo.Data(), cfg.Payload)
// ICMP checksum covers the entire ICMP message (no pseudo header).
icmpFrm.SetCRC(0)
var crc lneto.CRC791
icmpFrm.SetCRC(crc.PayloadSum16(icmpData[:totalPayload]))
return dst
}
func sizeWord(l int) uint8 {
return uint8((l + 3) / 4)
}