diff options
Diffstat (limited to 'pkg/tcpip/stack/packet_buffer.go')
| -rw-r--r-- | pkg/tcpip/stack/packet_buffer.go | 248 |
1 files changed, 237 insertions, 11 deletions
diff --git a/pkg/tcpip/stack/packet_buffer.go b/pkg/tcpip/stack/packet_buffer.go index 4f013b212..8f288675d 100644 --- a/pkg/tcpip/stack/packet_buffer.go +++ b/pkg/tcpip/stack/packet_buffer.go @@ -59,7 +59,7 @@ type PacketBuffer struct { // PacketBuffers. PacketBufferEntry - // Data holds the payload of the packet. + // data holds the payload of the packet. // // For inbound packets, Data is initially the whole packet. Then gets moved to // headers via PacketHeader.Consume, when the packet is being parsed. @@ -69,7 +69,7 @@ type PacketBuffer struct { // // The bytes backing Data are immutable, a.k.a. users shouldn't write to its // backing storage. - Data buffer.VectorisedView + data buffer.VectorisedView // headers stores metadata about each header. headers [numHeaderType]headerInfo @@ -127,7 +127,7 @@ type PacketBuffer struct { // NewPacketBuffer creates a new PacketBuffer with opts. func NewPacketBuffer(opts PacketBufferOptions) *PacketBuffer { pk := &PacketBuffer{ - Data: opts.Data, + data: opts.Data, } if opts.ReserveHeaderBytes != 0 { pk.header = buffer.NewPrependable(opts.ReserveHeaderBytes) @@ -184,13 +184,18 @@ func (pk *PacketBuffer) HeaderSize() int { // Size returns the size of packet in bytes. func (pk *PacketBuffer) Size() int { - return pk.HeaderSize() + pk.Data.Size() + return pk.HeaderSize() + pk.data.Size() } // MemSize returns the estimation size of the pk in memory, including backing // buffer data. func (pk *PacketBuffer) MemSize() int { - return pk.HeaderSize() + pk.Data.MemSize() + packetBufferStructSize + return pk.HeaderSize() + pk.data.MemSize() + packetBufferStructSize +} + +// Data returns the handle to data portion of pk. +func (pk *PacketBuffer) Data() PacketData { + return PacketData{pk: pk} } // Views returns the underlying storage of the whole packet. @@ -204,7 +209,7 @@ func (pk *PacketBuffer) Views() []buffer.View { } } - dataViews := pk.Data.Views() + dataViews := pk.data.Views() var vs []buffer.View if useHeader { @@ -242,11 +247,11 @@ func (pk *PacketBuffer) consume(typ headerType, size int) (v buffer.View, consum if h.buf != nil { panic(fmt.Sprintf("consume must not be called twice: type %s", typ)) } - v, ok := pk.Data.PullUp(size) + v, ok := pk.data.PullUp(size) if !ok { return } - pk.Data.TrimFront(size) + pk.data.TrimFront(size) h.buf = v return h.buf, true } @@ -258,7 +263,7 @@ func (pk *PacketBuffer) consume(typ headerType, size int) (v buffer.View, consum func (pk *PacketBuffer) Clone() *PacketBuffer { return &PacketBuffer{ PacketBufferEntry: pk.PacketBufferEntry, - Data: pk.Data.Clone(nil), + data: pk.data.Clone(nil), headers: pk.headers, header: pk.header, Hash: pk.Hash, @@ -339,13 +344,234 @@ func (h PacketHeader) Consume(size int) (v buffer.View, consumed bool) { return h.pk.consume(h.typ, size) } +// PacketData represents the data portion of a PacketBuffer. +type PacketData struct { + pk *PacketBuffer +} + +// PullUp returns a contiguous view of size bytes from the beginning of d. +// Callers should not write to or keep the view for later use. +func (d PacketData) PullUp(size int) (buffer.View, bool) { + return d.pk.data.PullUp(size) +} + +// TrimFront removes count from the beginning of d. It panics if count > +// d.Size(). +func (d PacketData) TrimFront(count int) { + d.pk.data.TrimFront(count) +} + +// CapLength reduces d to at most length bytes. +func (d PacketData) CapLength(length int) { + d.pk.data.CapLength(length) +} + +// Views returns the underlying storage of d in a slice of Views. Caller should +// not modify the returned slice. +func (d PacketData) Views() []buffer.View { + return d.pk.data.Views() +} + +// AppendView appends v into d, taking the ownership of v. +func (d PacketData) AppendView(v buffer.View) { + d.pk.data.AppendView(v) +} + +// ReadFromData moves at most count bytes from the beginning of srcData to the +// end of d and returns the number of bytes moved. +func (d PacketData) ReadFromData(srcData PacketData, count int) int { + return srcData.pk.data.ReadToVV(&d.pk.data, count) +} + +// ReadFromVV moves at most count bytes from the beginning of srcVV to the end +// of d and returns the number of bytes moved. +func (d PacketData) ReadFromVV(srcVV *buffer.VectorisedView, count int) int { + return srcVV.ReadToVV(&d.pk.data, count) +} + +// Size returns the number of bytes in the data payload of the packet. +func (d PacketData) Size() int { + return d.pk.data.Size() +} + +// AsRange returns a Range representing the current data payload of the packet. +func (d PacketData) AsRange() Range { + return Range{ + pk: d.pk, + offset: d.pk.HeaderSize(), + length: d.Size(), + } +} + +// ExtractVV returns a VectorisedView of d. This method has the semantic to +// destruct the underlying packet, hence the packet cannot be used again. +// +// This method exists for compatibility between PacketBuffer and VectorisedView. +// It may be removed later and should be used with care. +func (d PacketData) ExtractVV() buffer.VectorisedView { + return d.pk.data +} + +// Replace replaces the data portion of the packet with vv, taking the ownership +// of vv. +// +// This method exists for compatibility between PacketBuffer and VectorisedView. +// It may be removed later and should be used with care. +func (d PacketData) Replace(vv buffer.VectorisedView) { + d.pk.data = vv +} + +// Range represents a contiguous subportion of a PacketBuffer. +type Range struct { + pk *PacketBuffer + offset int + length int +} + +// Size returns the number of bytes in r. +func (r Range) Size() int { + return r.length +} + +// SubRange returns a new Range starting at off bytes of r. It returns an empty +// range if off is out-of-bounds. +func (r Range) SubRange(off int) Range { + if off > r.length { + return Range{pk: r.pk} + } + return Range{ + pk: r.pk, + offset: r.offset + off, + length: r.length - off, + } +} + +// Capped returns a new Range with the same starting point of r and length +// capped at max. +func (r Range) Capped(max int) Range { + if r.length <= max { + return r + } + return Range{ + pk: r.pk, + offset: r.offset, + length: max, + } +} + +// AsView returns the backing storage of r if possible. It will allocate a new +// View if r spans multiple pieces internally. Caller should not write to the +// returned View in any way. +func (r Range) AsView() buffer.View { + var allocated bool + var v buffer.View + r.iterate(func(b []byte) { + if v == nil { + // v has not been assigned, allowing first view to be returned. + v = b + } else { + // v has been assigned. This range spans more than a view, a new view + // needs to be allocated. + if !allocated { + allocated = true + all := make([]byte, 0, r.length) + all = append(all, v...) + v = all + } + v = append(v, b...) + } + }) + return v +} + +// ToOwnedView returns a owned copy of data in r. +func (r Range) ToOwnedView() buffer.View { + if r.length == 0 { + return nil + } + all := make([]byte, 0, r.length) + r.iterate(func(b []byte) { + all = append(all, b...) + }) + return all +} + +// Checksum calculates the RFC 1071 checksum for the underlying bytes of r. +func (r Range) Checksum() uint16 { + var c header.Checksumer + r.iterate(c.Add) + return c.Checksum() +} + +// iterate calls fn for each piece in r. fn is always called with a non-empty +// slice. +func (r Range) iterate(fn func([]byte)) { + w := window{ + offset: r.offset, + length: r.length, + } + // Header portion. + for i := range r.pk.headers { + if b := w.process(r.pk.headers[i].buf); len(b) > 0 { + fn(b) + } + if w.isDone() { + break + } + } + // Data portion. + if !w.isDone() { + for _, v := range r.pk.data.Views() { + if b := w.process(v); len(b) > 0 { + fn(b) + } + if w.isDone() { + break + } + } + } +} + +// window represents contiguous region of byte stream. User would call process() +// to input bytes, and obtain a subslice that is inside the window. +type window struct { + offset int + length int +} + +// isDone returns true if the window has passed and further process() calls will +// always return an empty slice. This can be used to end processing early. +func (w *window) isDone() bool { + return w.length == 0 +} + +// process feeds b in and returns a subslice that is inside the window. The +// returned slice will be a subslice of b, and it does not keep b after method +// returns. This method may return an empty slice if nothing in b is inside the +// window. +func (w *window) process(b []byte) (inWindow []byte) { + if w.offset >= len(b) { + w.offset -= len(b) + return nil + } + if w.offset > 0 { + b = b[w.offset:] + w.offset = 0 + } + if w.length < len(b) { + b = b[:w.length] + } + w.length -= len(b) + return b +} + // PayloadSince returns packet payload starting from and including a particular // header. // // The returned View is owned by the caller - its backing buffer is separate // from the packet header's underlying packet buffer. func PayloadSince(h PacketHeader) buffer.View { - size := h.pk.Data.Size() + size := h.pk.data.Size() for _, hinfo := range h.pk.headers[h.typ:] { size += len(hinfo.buf) } @@ -356,7 +582,7 @@ func PayloadSince(h PacketHeader) buffer.View { v = append(v, hinfo.buf...) } - for _, view := range h.pk.Data.Views() { + for _, view := range h.pk.data.Views() { v = append(v, view...) } |