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tcp: mss honoring; accept syn with ECE/CWR flags; add RSTQueue type (#41)
* tcp: mss honoring; accept syn with ECE/CWR flags; add RSTQueue type * tcp: move option logic to own file * remove prints in pcap * add MSS send threshold inspired by linux/freebsd/lwip thresh
This commit is contained in:
Pat Whittingslow
GitHub
@@ -5,7 +5,6 @@ import (
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"fmt"
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"math/bits"
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"strconv"
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"strings"
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"unsafe"
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)
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@@ -332,143 +331,3 @@ func (s State) isOpen() bool {
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func (s State) hasIRS() bool {
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return s.isOpen() && s != StateSynSent && s != StateListen
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}
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type OptionKind uint8
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const (
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OptEnd OptionKind = iota // end of option list
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OptNop // no-operation
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OptMaxSegmentSize // maximum segment size
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OptWindowScale // window scale
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OptSACKPermitted // SACK permitted
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OptSACK // SACK
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OptEcho // echo(obsolete)
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optEchoReply // echo reply(obsolete)
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OptTimestamps // timestamps
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optPOCP // partial order connection permitted(obsolete)
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optPOSP // partial order service profile(obsolete)
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optCC // CC(obsolete)
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optCCnew // CC.new(obsolete)
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optCCecho // CC.echo(obsolete)
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optACR // alternate checksum request(obsolete)
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optACD // alternate checksum data(obsolete)
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optSkeeter // skeeter
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optBubba // bubba
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OptTrailerChecksum // trailer checksum
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optMD5Signature // MD5 signature(obsolete)
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OptSCPSCapabilities // SCPS capabilities
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OptSNA // selective negative acks
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OptRecordBoundaries // record boundaries
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OptCorruptionExperienced // corruption experienced
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OptSNAP // SNAP
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OptUnassigned // unassigned
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OptCompressionFilter // compression filter
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OptQuickStartResponse // quick-start response
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OptUserTimeout // user timeout or unauthorized use
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OptAuthetication // Authentication TCP-AO
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OptMultipath // multipath TCP
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)
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const (
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OptFastOpenCookie OptionKind = 34 // fast open cookie
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OptEncryptionNegotiation OptionKind = 69 // encryption negotiation
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OptAccurateECN0 OptionKind = 172 // accurate ECN order 0
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OptAccurateECN1 OptionKind = 174 // accurate ECN order 1
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)
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// IsObsolete returns true if option considered obsolete by newer TCP specifications.
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func (kind OptionKind) IsObsolete() bool {
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if kind.IsDefined() {
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return strings.HasSuffix(kind.String(), "(obsolete)")
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}
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return false
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}
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// IsDefined returns true if the option is a known unreserved option kind.
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func (kind OptionKind) IsDefined() bool {
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return kind <= 30 || kind == 34 || kind == 69 || kind == 172 || kind == 174
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}
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type OptionCodec struct {
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Flags OptionFlags
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}
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type OptionFlags uint8
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const (
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OptFlagSkipSizeValidation OptionFlags = 1 << iota
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OptFlagSkipObsolete
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)
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func (flags OptionFlags) HasAny(ofTheseFlags OptionFlags) bool {
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return flags&ofTheseFlags != 0
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}
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func (op OptionCodec) PutOption16(dst []byte, kind OptionKind, v uint16) (int, error) {
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return op.PutOption(dst, kind, byte(v>>8), byte(v))
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}
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func (op OptionCodec) PutOption32(dst []byte, kind OptionKind, v uint32) (int, error) {
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return op.PutOption(dst, kind, byte(v>>24), byte(v>>16), byte(v>>7), byte(v))
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}
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func (op OptionCodec) PutOption(dst []byte, kind OptionKind, data ...byte) (int, error) {
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putSize := 2 + len(data)
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if len(dst) < putSize {
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return -1, errBufferTooSmall
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} else if putSize > 255 {
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return -1, errors.New("option data too large")
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} else if kind == OptNop || kind == OptEnd {
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return -1, errors.New("cant put Nop or End option type")
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}
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dst[0] = byte(kind)
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dst[1] = byte(putSize)
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copy(dst[2:], data)
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return putSize, nil
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}
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func (op OptionCodec) ForEachOption(opts []byte, fn func(OptionKind, []byte) error) error {
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off := 0
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skipSizeValidation := op.Flags.HasAny(OptFlagSkipSizeValidation)
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skipObsolete := op.Flags.HasAny(OptFlagSkipObsolete)
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for off < len(opts) && opts[off] != 0 {
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kind := OptionKind(opts[off])
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off++
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if kind == OptNop {
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continue
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}
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if len(opts[off:]) < 2 {
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return errors.New("short TCP options")
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}
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size := int(opts[off])
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off++
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if len(opts[off:]) < size {
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return fmt.Errorf("option %q length %d exceeds buffer size %d", kind.String(), size, len(opts[off:]))
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}
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if !skipSizeValidation {
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expectSize := -1
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switch kind {
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case OptTimestamps:
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expectSize = 10
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case OptMaxSegmentSize, OptUserTimeout:
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expectSize = 4
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case OptWindowScale:
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expectSize = 3
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case OptSACKPermitted:
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expectSize = 2
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}
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if expectSize != -1 && size != expectSize {
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return fmt.Errorf("bad TCP option %q size want %d got %d", kind.String(), expectSize, opts[off])
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}
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}
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if skipObsolete && kind.IsObsolete() {
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err := fn(kind, opts[off:off+size])
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if err != nil {
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return err
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}
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}
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off += size
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}
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return nil
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}
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