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fix TCP checksum in internet.StackBasic; more logging

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soypat
2025-05-27 23:37:21 -03:00
parent a967f083cb
commit 20946c7e22
7 changed files with 133 additions and 35 deletions
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internet/basicstack.go
+31 -21
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@@ -38,35 +38,41 @@ func (sb *StackBasic) Addr() netip.Addr {
}
func (sb *StackBasic) Recv(frame []byte) error {
sb.info("StackBasic.Recv:start")
ifrm, err := ipv4.NewFrame(frame)
if err != nil {
return err
}
dst := ifrm.DestinationAddr()
if *dst != sb.ip {
return errors.New("packet not for us")
goto DROP
}
sb.validator.ResetErr()
ifrm.ValidateExceptCRC(&sb.validator)
if err = sb.validator.Err(); err != nil {
return err
}
gotCRC := ifrm.CRC()
wantCRC := ifrm.CalculateHeaderCRC()
if gotCRC != wantCRC {
sb.error("IPv4Stack:Recv:crc-mismatch", slog.Uint64("want", uint64(wantCRC)), slog.Uint64("got", uint64(gotCRC)))
return errors.New("IPv4 CRC mismatch")
}
off := ifrm.HeaderLength()
totalLen := ifrm.TotalLength()
for i := range sb.handlers {
h := &sb.handlers[i]
proto := ifrm.Protocol()
if h.proto == proto {
sb.info("iprecv", slog.String("ipproto", proto.String()), slog.Int("plen", int(totalLen)))
return h.recv(frame[:totalLen], off)
{
sb.validator.ResetErr()
ifrm.ValidateExceptCRC(&sb.validator)
if err = sb.validator.Err(); err != nil {
return err
}
gotCRC := ifrm.CRC()
wantCRC := ifrm.CalculateHeaderCRC()
if gotCRC != wantCRC {
sb.error("IPv4Stack:Recv:crc-mismatch", slog.Uint64("want", uint64(wantCRC)), slog.Uint64("got", uint64(gotCRC)))
return errors.New("IPv4 CRC mismatch")
}
off := ifrm.HeaderLength()
totalLen := ifrm.TotalLength()
for i := range sb.handlers {
h := &sb.handlers[i]
proto := ifrm.Protocol()
if h.proto == proto {
sb.info("iprecv", slog.String("ipproto", proto.String()), slog.Int("plen", int(totalLen)))
return h.recv(frame[:totalLen], off)
}
}
}
DROP:
sb.info("iprecv:drop", slog.String("dstaddr", netip.AddrFrom4(*ifrm.DestinationAddr()).String()), slog.String("proto", ifrm.Protocol().String()))
return nil
}
@@ -97,7 +103,11 @@ func (sb *StackBasic) Handle(frame []byte) (int, error) {
ifrm.SetProtocol(h.proto)
ifrm.SetCRC(ifrm.CalculateHeaderCRC())
if ifrm.Protocol() == lneto.IPProtoTCP {
var crc lneto.CRC791
ifrm.CRCWriteTCPPseudo(&crc)
tfrm, _ := tcp.NewFrame(ifrm.Payload())
tfrm.CRCWrite(&crc)
tfrm.SetCRC(crc.Sum16())
sb.info("IPv4Stack:send", slog.String("ip", ifrm.String()), slog.String("tcp", tfrm.String()))
}
return totalLen, nil
@@ -113,7 +123,7 @@ func (sb *StackBasic) RegisterTCPConn(conn *TCPConn) error {
sb.handlers = append(sb.handlers, handler{
recv: conn.RecvIP,
handle: conn.HandleIP,
proto: lneto.IPProtoIPv4,
proto: lneto.IPProtoTCP,
port: conn.LocalPort(),
})
return nil