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rephrase tcp.Value methods; add Ring.FreeLimited; work on TxQueue

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This commit is contained in:
soypat
2025-01-18 09:30:36 -03:00
parent 93d1f80015
commit 51ca0a95b5
5 changed files with 95 additions and 39 deletions
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internal/ring.go
+13 -7
View File
@@ -23,8 +23,19 @@ type Ring struct {
End int
}
// SizeLimited returns the amount of bytes that can be written up to the
// argument offset limitOffset. See [Ring.WriteLimited]
func (r *Ring) FreeLimited(limitOffset int) (free int) {
if limitOffset > r.End {
free = limitOffset - r.End
} else {
free = len(r.Buf) - r.End + limitOffset
}
return free
}
// WriteLimited performs a write that does not write over the ring buffer's
// limitOffset index, which points to a position to r.Buf.
// limitOffset index, which points to a position to r.Buf. Up to [Ring.FreeLimited] bytes can be written.
func (r *Ring) WriteLimited(b []byte, limitOffset int) (int, error) {
if limitOffset > len(r.Buf) {
panic("bad limit offset")
@@ -32,12 +43,7 @@ func (r *Ring) WriteLimited(b []byte, limitOffset int) (int, error) {
if len(b) > len(r.Buf) {
return 0, io.ErrShortBuffer
}
var limit int
if limitOffset > r.End {
limit = limitOffset - r.End
} else {
limit = len(r.Buf) - r.End + limitOffset
}
limit := r.FreeLimited(limitOffset)
if len(b) > limit {
return 0, errRingBufferFull
}
tcp/control.go
+6 -6
View File
@@ -352,7 +352,7 @@ func (tcb *ControlBlock) validateOutgoingSegment(seg Segment) (err error) {
seglast := seg.Last()
// Extra check for when send Window is zero and no data is being sent.
zeroWindowOK := tcb.snd.WND == 0 && seg.DATALEN == 0 && seg.SEQ == tcb.snd.NXT
outOfWindow := checkSeq && !InWindow(seg.SEQ, tcb.snd.NXT, tcb.snd.WND) &&
outOfWindow := checkSeq && !seg.SEQ.InWindow(tcb.snd.NXT, tcb.snd.WND) &&
!zeroWindowOK
switch {
case tcb.state == StateClosed:
@@ -375,7 +375,7 @@ func (tcb *ControlBlock) validateOutgoingSegment(seg Segment) (err error) {
case checkSeq && tcb.snd.WND == 0 && seg.DATALEN > 0 && seg.SEQ == tcb.snd.NXT:
err = errZeroWindow
case checkSeq && !InWindow(seglast, tcb.snd.NXT, tcb.snd.WND) && !zeroWindowOK:
case checkSeq && !seglast.InWindow(tcb.snd.NXT, tcb.snd.WND) && !zeroWindowOK:
err = errLastNotInWindow
}
return err
@@ -388,8 +388,8 @@ func (tcb *ControlBlock) validateIncomingSegment(seg Segment) (err error) {
checkSEQ := !flags.HasAny(FlagSYN)
established := tcb.state == StateEstablished
preestablished := tcb.state.IsPreestablished()
acksOld := hasAck && !LessThan(tcb.snd.UNA, seg.ACK)
acksUnsentData := hasAck && !LessThanEq(seg.ACK, tcb.snd.NXT)
acksOld := hasAck && !tcb.snd.UNA.LessThan(seg.ACK)
acksUnsentData := hasAck && !seg.ACK.LessThanEq(tcb.snd.NXT)
ctlOrDataSegment := established && (seg.DATALEN > 0 || flags.HasAny(FlagFIN|FlagRST))
zeroWindowOK := tcb.rcv.WND == 0 && seg.DATALEN == 0 && seg.SEQ == tcb.rcv.NXT
// See section 3.4 of RFC 9293 for more on these checks.
@@ -402,10 +402,10 @@ func (tcb *ControlBlock) validateIncomingSegment(seg Segment) (err error) {
case checkSEQ && tcb.rcv.WND == 0 && seg.DATALEN > 0 && seg.SEQ == tcb.rcv.NXT:
err = errZeroWindow
case checkSEQ && !InWindow(seg.SEQ, tcb.rcv.NXT, tcb.rcv.WND) && !zeroWindowOK:
case checkSEQ && !seg.SEQ.InWindow(tcb.rcv.NXT, tcb.rcv.WND) && !zeroWindowOK:
err = errSeqNotInWindow
case checkSEQ && !InWindow(seg.Last(), tcb.rcv.NXT, tcb.rcv.WND) && !zeroWindowOK:
case checkSEQ && !seg.Last().InWindow(tcb.rcv.NXT, tcb.rcv.WND) && !zeroWindowOK:
err = errLastNotInWindow
case checkSEQ && seg.SEQ != tcb.rcv.NXT:
tcp/txqueue.go
+69 -20
View File
@@ -23,9 +23,9 @@ type ringTx struct {
rawbuf []byte
// packets contains
packets []ringidx
// firstPkt is the index of the oldest packet in the packets field.
firstPkt int
lastPkt int
// _firstPkt is the index of the oldest packet in the packets field.
_firstPkt int
_lastPkt int
// unsentOff is the offset of start of unsent data into rawbuf.
unsentoff int
// unsentend is the offset of end of unsent data in rawbuf.
@@ -58,21 +58,27 @@ func (tx *ringTx) BufferedSent() int {
}
// Write writes data to the underlying unsent data ring buffer.
func (tx *ringTx) Write(b []byte) (int, error) {
first := tx.packets[tx.firstPkt]
func (tx *ringTx) Write(b []byte) (n int, err error) {
first := tx.packets[tx._firstPkt]
r := tx.unsentRing()
if first.off < 0 {
// No packets in queue case.
return r.Write(b)
n, err = r.Write(b)
} else {
n, err = r.WriteLimited(b, first.off)
}
return r.WriteLimited(b, first.off)
if err != nil {
return 0, err
}
tx.unsentend = tx.addOff(tx.unsentend, n)
return n, err
}
// MakePacket reads from the unsent data ring buffer and generates a new packet segment.
// It fails if the sent packet queue is full.
func (tx *ringTx) MakePacket(b []byte) (int, error) {
nxtpkt := (tx.lastPkt + 1) % len(tx.packets)
if tx.firstPkt == nxtpkt {
nxtpkt := (tx._lastPkt + 1) % len(tx.packets)
if tx._firstPkt == nxtpkt {
return 0, errors.New("packet queue full")
}
@@ -82,20 +88,20 @@ func (tx *ringTx) MakePacket(b []byte) (int, error) {
if err != nil {
return n, err
}
last := &tx.packets[tx.lastPkt]
rlast := tx.packetRing(tx.lastPkt)
last := &tx.packets[tx._lastPkt]
rlast := tx.packetRing(tx._lastPkt)
tx.packets[nxtpkt].off = start
tx.packets[nxtpkt].end = r.Off
tx.packets[nxtpkt].end = tx.addOff(start, n)
tx.packets[nxtpkt].seq = last.seq + Value(rlast.Buffered())
tx.lastPkt = nxtpkt
tx.unsentoff = r.Off
tx._lastPkt = nxtpkt
tx.unsentoff = tx.addOff(tx.unsentoff, n)
return n, nil
}
// IsQueueFull returns true if the sent packet queue is full in which
// case a call to ReadPacket is guaranteed to fail.
func (tx *ringTx) IsQueueFull() bool {
return tx.firstPkt == (tx.lastPkt+1)%len(tx.packets)
return tx._firstPkt == (tx._lastPkt+1)%len(tx.packets)
}
func (tx *ringTx) packetRing(i int) internal.Ring {
@@ -108,16 +114,16 @@ func (tx *ringTx) packetRing(i int) internal.Ring {
// RecvSegment processes an incoming segment and updates the sent packet queue
func (tx *ringTx) RecvACK(ack Value) error {
i := tx.firstPkt
i := tx._firstPkt
for {
pkt := &tx.packets[i]
if ack >= pkt.seq {
// Packet was received by remote. Mark it as acked.
pkt.off = -1
tx.firstPkt++
tx._firstPkt++
continue
}
if i == tx.lastPkt {
if i == tx._lastPkt {
break
}
i = (i + 1) % len(tx.packets)
@@ -129,15 +135,58 @@ func (tx *ringTx) unsentRing() internal.Ring {
return tx.ring(tx.unsentoff, tx.unsentend)
}
func (tx *ringTx) freeRing() (internal.Ring, int) {
return tx.ring(tx.unsentoff, tx.unsentend), 0
}
func (tx *ringTx) a() {
}
func (tx *ringTx) sentRing() internal.Ring {
first := tx.packets[tx.firstPkt]
first := tx.packets[tx._firstPkt]
if first.off < 0 {
return tx.ring(0, 0)
}
last := tx.packets[tx.lastPkt]
last := tx.packets[tx._lastPkt]
return tx.ring(first.off, last.end)
}
func (tx *ringTx) ring(off, end int) internal.Ring {
return internal.Ring{Buf: tx.rawbuf, Off: off, End: end}
}
// addOff adds two integers together and wraps the value around the ring's buffer size.
func (tx *ringTx) addOff(a, b int) int {
off := a + b
if off >= len(tx.rawbuf) {
off -= len(tx.rawbuf)
}
return off
}
func (tx *ringTx) firstPkt() int {
seq := tx.packets[0].seq
idx := -1
for i := 0; i < len(tx.packets); i++ {
pkt := &tx.packets[i]
if (pkt.end != 0 || pkt.off != 0) && seq.LessThanEq(pkt.seq) {
seq = pkt.seq
idx = i
}
}
return idx
}
func (tx *ringTx) lastPkt() int {
seq := tx.packets[0].seq
idx := -1
for i := 0; i < len(tx.packets); i++ {
pkt := &tx.packets[i]
if (pkt.end != 0 || pkt.off != 0) && pkt.seq.LessThanEq(seq) {
seq = pkt.seq
idx = i
}
}
return idx
}
tcp/txqueue_test.go
+1
View File
@@ -23,6 +23,7 @@ func TestTxQueueWrite(t *testing.T) {
} else if n != len(buf) {
t.Fatalf("want %d written, got %d", len(buf), n)
}
n, err = rtx.MakePacket(data[:])
if err != nil {
t.Fatalf("making packet %d: %s", i, err)
tcp/valuesize.go
+6 -6
View File
@@ -24,24 +24,24 @@ type Value uint32
type Size uint32
// LessThan checks if v is before w (modulo 32) i.e., v < w.
func LessThan(v, w Value) bool {
func (v Value) LessThan(w Value) bool {
return int32(v-w) < 0
}
// LessThanEq returns true if v==w or v is before (modulo 32) i.e., v < w.
func LessThanEq(v, w Value) bool {
return v == w || LessThan(v, w)
func (v Value) LessThanEq(w Value) bool {
return v == w || v.LessThan(w)
}
// InRange checks if v is in the range [a,b) (modulo 32), i.e., a <= v < b.
func InRange(v, a, b Value) bool {
func (v Value) InRange(a, b Value) bool {
return v-a < b-a
}
// InWindow checks if v is in the window that starts at 'first' and spans 'size'
// sequence numbers (modulo 32).
func InWindow(v, first Value, size Size) bool {
return InRange(v, first, Add(first, size))
func (v Value) InWindow(first Value, size Size) bool {
return v.InRange(first, Add(first, size))
}
// Add calculates the sequence number following the [v, v+s) window.