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Diffstat (limited to 'vendor/github.com/google/gopacket/writer.go')
| -rw-r--r-- | vendor/github.com/google/gopacket/writer.go | 213 |
1 files changed, 0 insertions, 213 deletions
diff --git a/vendor/github.com/google/gopacket/writer.go b/vendor/github.com/google/gopacket/writer.go deleted file mode 100644 index 9e85a92..0000000 --- a/vendor/github.com/google/gopacket/writer.go +++ /dev/null @@ -1,213 +0,0 @@ -// Copyright 2012 Google, Inc. All rights reserved. -// -// Use of this source code is governed by a BSD-style license -// that can be found in the LICENSE file in the root of the source -// tree. - -package gopacket - -import ( - "fmt" -) - -// SerializableLayer allows its implementations to be written out as a set of bytes, -// so those bytes may be sent on the wire or otherwise used by the caller. -// SerializableLayer is implemented by certain Layer types, and can be encoded to -// bytes using the LayerWriter object. -type SerializableLayer interface { - // SerializeTo writes this layer to a slice, growing that slice if necessary - // to make it fit the layer's data. - // Args: - // b: SerializeBuffer to write this layer on to. When called, b.Bytes() - // is the payload this layer should wrap, if any. Note that this - // layer can either prepend itself (common), append itself - // (uncommon), or both (sometimes padding or footers are required at - // the end of packet data). It's also possible (though probably very - // rarely needed) to overwrite any bytes in the current payload. - // After this call, b.Bytes() should return the byte encoding of - // this layer wrapping the original b.Bytes() payload. - // opts: options to use while writing out data. - // Returns: - // error if a problem was encountered during encoding. If an error is - // returned, the bytes in data should be considered invalidated, and - // not used. - // - // SerializeTo calls SHOULD entirely ignore LayerContents and - // LayerPayload. It just serializes based on struct fields, neither - // modifying nor using contents/payload. - SerializeTo(b SerializeBuffer, opts SerializeOptions) error -} - -// SerializeOptions provides options for behaviors that SerializableLayers may want to -// implement. -type SerializeOptions struct { - // FixLengths determines whether, during serialization, layers should fix - // the values for any length field that depends on the payload. - FixLengths bool - // ComputeChecksums determines whether, during serialization, layers - // should recompute checksums based on their payloads. - ComputeChecksums bool -} - -// SerializeBuffer is a helper used by gopacket for writing out packet layers. -// SerializeBuffer starts off as an empty []byte. Subsequent calls to PrependBytes -// return byte slices before the current Bytes(), AppendBytes returns byte -// slices after. -// -// Byte slices returned by PrependBytes/AppendBytes are NOT zero'd out, so if -// you want to make sure they're all zeros, set them as such. -// -// SerializeBuffer is specifically designed to handle packet writing, where unlike -// with normal writes it's easier to start writing at the inner-most layer and -// work out, meaning that we often need to prepend bytes. This runs counter to -// typical writes to byte slices using append(), where we only write at the end -// of the buffer. -// -// It can be reused via Clear. Note, however, that a Clear call will invalidate the -// byte slices returned by any previous Bytes() call (the same buffer is -// reused). -// -// 1) Reusing a write buffer is generally much faster than creating a new one, -// and with the default implementation it avoids additional memory allocations. -// 2) If a byte slice from a previous Bytes() call will continue to be used, -// it's better to create a new SerializeBuffer. -// -// The Clear method is specifically designed to minimize memory allocations for -// similar later workloads on the SerializeBuffer. IE: if you make a set of -// Prepend/Append calls, then clear, then make the same calls with the same -// sizes, the second round (and all future similar rounds) shouldn't allocate -// any new memory. -type SerializeBuffer interface { - // Bytes returns the contiguous set of bytes collected so far by Prepend/Append - // calls. The slice returned by Bytes will be modified by future Clear calls, - // so if you're planning on clearing this SerializeBuffer, you may want to copy - // Bytes somewhere safe first. - Bytes() []byte - // PrependBytes returns a set of bytes which prepends the current bytes in this - // buffer. These bytes start in an indeterminate state, so they should be - // overwritten by the caller. The caller must only call PrependBytes if they - // know they're going to immediately overwrite all bytes returned. - PrependBytes(num int) ([]byte, error) - // AppendBytes returns a set of bytes which appends the current bytes in this - // buffer. These bytes start in an indeterminate state, so they should be - // overwritten by the caller. The caller must only call AppendBytes if they - // know they're going to immediately overwrite all bytes returned. - AppendBytes(num int) ([]byte, error) - // Clear resets the SerializeBuffer to a new, empty buffer. After a call to clear, - // the byte slice returned by any previous call to Bytes() for this buffer - // should be considered invalidated. - Clear() error -} - -type serializeBuffer struct { - data []byte - start int - prepended, appended int -} - -// NewSerializeBuffer creates a new instance of the default implementation of -// the SerializeBuffer interface. -func NewSerializeBuffer() SerializeBuffer { - return &serializeBuffer{} -} - -// NewSerializeBufferExpectedSize creates a new buffer for serialization, optimized for an -// expected number of bytes prepended/appended. This tends to decrease the -// number of memory allocations made by the buffer during writes. -func NewSerializeBufferExpectedSize(expectedPrependLength, expectedAppendLength int) SerializeBuffer { - return &serializeBuffer{ - data: make([]byte, expectedPrependLength, expectedPrependLength+expectedAppendLength), - start: expectedPrependLength, - prepended: expectedPrependLength, - appended: expectedAppendLength, - } -} - -func (w *serializeBuffer) Bytes() []byte { - return w.data[w.start:] -} - -func (w *serializeBuffer) PrependBytes(num int) ([]byte, error) { - if num < 0 { - panic("num < 0") - } - if w.start < num { - toPrepend := w.prepended - if toPrepend < num { - toPrepend = num - } - w.prepended += toPrepend - length := cap(w.data) + toPrepend - newData := make([]byte, length) - newStart := w.start + toPrepend - copy(newData[newStart:], w.data[w.start:]) - w.start = newStart - w.data = newData[:toPrepend+len(w.data)] - } - w.start -= num - return w.data[w.start : w.start+num], nil -} - -func (w *serializeBuffer) AppendBytes(num int) ([]byte, error) { - if num < 0 { - panic("num < 0") - } - initialLength := len(w.data) - if cap(w.data)-initialLength < num { - toAppend := w.appended - if toAppend < num { - toAppend = num - } - w.appended += toAppend - newData := make([]byte, cap(w.data)+toAppend) - copy(newData[w.start:], w.data[w.start:]) - w.data = newData[:initialLength] - } - // Grow the buffer. We know it'll be under capacity given above. - w.data = w.data[:initialLength+num] - return w.data[initialLength:], nil -} - -func (w *serializeBuffer) Clear() error { - w.start = w.prepended - w.data = w.data[:w.start] - return nil -} - -// SerializeLayers clears the given write buffer, then writes all layers into it so -// they correctly wrap each other. Note that by clearing the buffer, it -// invalidates all slices previously returned by w.Bytes() -// -// Example: -// buf := gopacket.NewSerializeBuffer() -// opts := gopacket.SerializeOptions{} -// gopacket.SerializeLayers(buf, opts, a, b, c) -// firstPayload := buf.Bytes() // contains byte representation of a(b(c)) -// gopacket.SerializeLayers(buf, opts, d, e, f) -// secondPayload := buf.Bytes() // contains byte representation of d(e(f)). firstPayload is now invalidated, since the SerializeLayers call Clears buf. -func SerializeLayers(w SerializeBuffer, opts SerializeOptions, layers ...SerializableLayer) error { - w.Clear() - for i := len(layers) - 1; i >= 0; i-- { - layer := layers[i] - err := layer.SerializeTo(w, opts) - if err != nil { - return err - } - } - return nil -} - -// SerializePacket is a convenience function that calls SerializeLayers -// on packet's Layers(). -// It returns an error if one of the packet layers is not a SerializebleLayer. -func SerializePacket(buf SerializeBuffer, opts SerializeOptions, packet Packet) error { - sls := []SerializableLayer{} - for _, layer := range packet.Layers() { - sl, ok := layer.(SerializableLayer) - if !ok { - return fmt.Errorf("layer %s is not serializable", layer.LayerType().String()) - } - sls = append(sls, sl) - } - return SerializeLayers(buf, opts, sls...) -} |