mirror of
https://github.com/go-gitea/gitea
synced 2024-12-25 13:14:48 +01:00
482 lines
14 KiB
Go
482 lines
14 KiB
Go
package gomemcached
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import (
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"encoding/binary"
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"fmt"
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"io"
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)
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// The maximum reasonable body length to expect.
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// Anything larger than this will result in an error.
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// The current limit, 20MB, is the size limit supported by ep-engine.
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var MaxBodyLen = int(20 * 1024 * 1024)
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// MCRequest is memcached Request
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type MCRequest struct {
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// The command being issued
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Opcode CommandCode
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// The CAS (if applicable, or 0)
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Cas uint64
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// An opaque value to be returned with this request
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Opaque uint32
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// The vbucket to which this command belongs
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VBucket uint16
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// Command extras, key, and body
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Extras, Key, Body, ExtMeta []byte
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// Datatype identifier
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DataType uint8
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// len() calls are expensive - cache this in case for collection
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Keylen int
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// Flexible Framing Extras
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FramingExtras []FrameInfo
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// Stored length of incoming framing extras
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FramingElen int
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}
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// Size gives the number of bytes this request requires.
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func (req *MCRequest) Size() int {
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return HDR_LEN + len(req.Extras) + len(req.Key) + len(req.Body) + len(req.ExtMeta) + req.FramingElen
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}
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// A debugging string representation of this request
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func (req MCRequest) String() string {
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return fmt.Sprintf("{MCRequest opcode=%s, bodylen=%d, key='%s'}",
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req.Opcode, len(req.Body), req.Key)
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}
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func (req *MCRequest) fillRegularHeaderBytes(data []byte) int {
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// Byte/ 0 | 1 | 2 | 3 |
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// / | | | |
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// |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
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// +---------------+---------------+---------------+---------------+
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// 0| Magic | Opcode | Key length |
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// +---------------+---------------+---------------+---------------+
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// 4| Extras length | Data type | vbucket id |
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// +---------------+---------------+---------------+---------------+
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// 8| Total body length |
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// +---------------+---------------+---------------+---------------+
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// 12| Opaque |
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// +---------------+---------------+---------------+---------------+
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// 16| CAS |
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// | |
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// +---------------+---------------+---------------+---------------+
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// Total 24 bytes
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pos := 0
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data[pos] = REQ_MAGIC
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pos++
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data[pos] = byte(req.Opcode)
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pos++
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binary.BigEndian.PutUint16(data[pos:pos+2],
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uint16(len(req.Key)))
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pos += 2
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// 4
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data[pos] = byte(len(req.Extras))
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pos++
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// Data type
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if req.DataType != 0 {
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data[pos] = byte(req.DataType)
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}
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pos++
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binary.BigEndian.PutUint16(data[pos:pos+2], req.VBucket)
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pos += 2
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// 8
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binary.BigEndian.PutUint32(data[pos:pos+4],
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uint32(len(req.Body)+len(req.Key)+len(req.Extras)+len(req.ExtMeta)))
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pos += 4
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// 12
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binary.BigEndian.PutUint32(data[pos:pos+4], req.Opaque)
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pos += 4
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// 16
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if req.Cas != 0 {
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binary.BigEndian.PutUint64(data[pos:pos+8], req.Cas)
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}
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pos += 8
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if len(req.Extras) > 0 {
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copy(data[pos:pos+len(req.Extras)], req.Extras)
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pos += len(req.Extras)
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}
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if len(req.Key) > 0 {
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copy(data[pos:pos+len(req.Key)], req.Key)
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pos += len(req.Key)
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}
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return pos
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}
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// Returns pos and if trailing by half byte
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func (req *MCRequest) fillFlexHeaderBytes(data []byte) (int, bool) {
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// Byte/ 0 | 1 | 2 | 3 |
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// / | | | |
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// |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
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// +---------------+---------------+---------------+---------------+
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// 0| Magic (0x08) | Opcode | Framing extras| Key Length |
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// +---------------+---------------+---------------+---------------+
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// 4| Extras length | Data type | vbucket id |
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// +---------------+---------------+---------------+---------------+
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// 8| Total body length |
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// +---------------+---------------+---------------+---------------+
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// 12| Opaque |
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// +---------------+---------------+---------------+---------------+
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// 16| CAS |
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// | |
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// +---------------+---------------+---------------+---------------+
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// Total 24 bytes
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data[0] = FLEX_MAGIC
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data[1] = byte(req.Opcode)
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data[2] = byte(req.FramingElen)
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data[3] = byte(req.Keylen)
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elen := len(req.Extras)
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data[4] = byte(elen)
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if req.DataType != 0 {
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data[5] = byte(req.DataType)
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}
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binary.BigEndian.PutUint16(data[6:8], req.VBucket)
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binary.BigEndian.PutUint32(data[8:12],
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uint32(len(req.Body)+req.Keylen+elen+len(req.ExtMeta)+req.FramingElen))
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binary.BigEndian.PutUint32(data[12:16], req.Opaque)
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if req.Cas != 0 {
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binary.BigEndian.PutUint64(data[16:24], req.Cas)
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}
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pos := HDR_LEN
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// Add framing infos
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var framingExtras []byte
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var outputBytes []byte
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var mergeModeSrc []byte
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var frameBytes int
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var halfByteMode bool
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var mergeMode bool
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for _, frameInfo := range req.FramingExtras {
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if !mergeMode {
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outputBytes, halfByteMode = frameInfo.Bytes()
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if !halfByteMode {
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framingExtras = append(framingExtras, outputBytes...)
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frameBytes += len(outputBytes)
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} else {
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mergeMode = true
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mergeModeSrc = outputBytes
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}
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} else {
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outputBytes, halfByteMode = frameInfo.Bytes()
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outputBytes := ShiftByteSliceRight4Bits(outputBytes)
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if halfByteMode {
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// Previous halfbyte merge with this halfbyte will result in a complete byte
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mergeMode = false
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outputBytes = Merge2HalfByteSlices(mergeModeSrc, outputBytes)
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framingExtras = append(framingExtras, outputBytes...)
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frameBytes += len(outputBytes)
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} else {
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// Merge half byte with a non-half byte will result in a combined half-byte that will
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// become the source for the next iteration
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mergeModeSrc = Merge2HalfByteSlices(mergeModeSrc, outputBytes)
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}
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}
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}
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if mergeMode {
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// Commit the temporary merge area into framingExtras
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framingExtras = append(framingExtras, mergeModeSrc...)
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frameBytes += len(mergeModeSrc)
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}
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copy(data[pos:pos+frameBytes], framingExtras)
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pos += frameBytes
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// Add Extras
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if len(req.Extras) > 0 {
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if mergeMode {
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outputBytes = ShiftByteSliceRight4Bits(req.Extras)
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data = Merge2HalfByteSlices(data, outputBytes)
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} else {
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copy(data[pos:pos+elen], req.Extras)
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}
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pos += elen
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}
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// Add keys
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if req.Keylen > 0 {
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if mergeMode {
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outputBytes = ShiftByteSliceRight4Bits(req.Key)
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data = Merge2HalfByteSlices(data, outputBytes)
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} else {
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copy(data[pos:pos+req.Keylen], req.Key)
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}
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pos += req.Keylen
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}
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return pos, mergeMode
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}
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func (req *MCRequest) FillHeaderBytes(data []byte) (int, bool) {
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if req.FramingElen == 0 {
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return req.fillRegularHeaderBytes(data), false
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} else {
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return req.fillFlexHeaderBytes(data)
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}
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}
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// HeaderBytes will return the wire representation of the request header
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// (with the extras and key).
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func (req *MCRequest) HeaderBytes() []byte {
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data := make([]byte, HDR_LEN+len(req.Extras)+len(req.Key)+req.FramingElen)
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req.FillHeaderBytes(data)
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return data
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}
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// Bytes will return the wire representation of this request.
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func (req *MCRequest) Bytes() []byte {
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data := make([]byte, req.Size())
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pos, halfByteMode := req.FillHeaderBytes(data)
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// TODO - the halfByteMode should be revisited for a more efficient
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// way of doing things
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if len(req.Body) > 0 {
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if halfByteMode {
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shifted := ShiftByteSliceRight4Bits(req.Body)
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data = Merge2HalfByteSlices(data, shifted)
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} else {
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copy(data[pos:pos+len(req.Body)], req.Body)
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}
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}
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if len(req.ExtMeta) > 0 {
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if halfByteMode {
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shifted := ShiftByteSliceRight4Bits(req.ExtMeta)
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data = Merge2HalfByteSlices(data, shifted)
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} else {
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copy(data[pos+len(req.Body):pos+len(req.Body)+len(req.ExtMeta)], req.ExtMeta)
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}
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}
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return data
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}
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// Transmit will send this request message across a writer.
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func (req *MCRequest) Transmit(w io.Writer) (n int, err error) {
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if len(req.Body) < 128 {
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n, err = w.Write(req.Bytes())
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} else {
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n, err = w.Write(req.HeaderBytes())
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if err == nil {
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m := 0
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m, err = w.Write(req.Body)
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n += m
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}
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}
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return
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}
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func (req *MCRequest) receiveHeaderCommon(hdrBytes []byte) (elen, totalBodyLen int) {
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elen = int(hdrBytes[4])
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// Data type at 5
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req.DataType = uint8(hdrBytes[5])
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req.Opcode = CommandCode(hdrBytes[1])
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// Vbucket at 6:7
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req.VBucket = binary.BigEndian.Uint16(hdrBytes[6:])
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totalBodyLen = int(binary.BigEndian.Uint32(hdrBytes[8:]))
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req.Opaque = binary.BigEndian.Uint32(hdrBytes[12:])
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req.Cas = binary.BigEndian.Uint64(hdrBytes[16:])
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return
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}
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func (req *MCRequest) receiveRegHeader(hdrBytes []byte) (elen, totalBodyLen int) {
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elen, totalBodyLen = req.receiveHeaderCommon(hdrBytes)
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req.Keylen = int(binary.BigEndian.Uint16(hdrBytes[2:]))
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return
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}
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func (req *MCRequest) receiveFlexibleFramingHeader(hdrBytes []byte) (elen, totalBodyLen, framingElen int) {
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elen, totalBodyLen = req.receiveHeaderCommon(hdrBytes)
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// For flexible framing header, key length is a single byte at byte index 3
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req.Keylen = int(binary.BigEndian.Uint16(hdrBytes[2:]) & 0x0ff)
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// Flexible framing lengh is a single byte at index 2
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framingElen = int(binary.BigEndian.Uint16(hdrBytes[2:]) >> 8)
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req.FramingElen = framingElen
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return
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}
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func (req *MCRequest) populateRegularBody(r io.Reader, totalBodyLen, elen int) (int, error) {
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var m int
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var err error
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if totalBodyLen > 0 {
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buf := make([]byte, totalBodyLen)
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m, err = io.ReadFull(r, buf)
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if err == nil {
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if req.Opcode >= TAP_MUTATION &&
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req.Opcode <= TAP_CHECKPOINT_END &&
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len(buf) > 1 {
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// In these commands there is "engine private"
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// data at the end of the extras. The first 2
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// bytes of extra data give its length.
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elen += int(binary.BigEndian.Uint16(buf))
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}
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req.Extras = buf[0:elen]
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req.Key = buf[elen : req.Keylen+elen]
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// get the length of extended metadata
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extMetaLen := 0
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if elen > 29 {
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extMetaLen = int(binary.BigEndian.Uint16(req.Extras[28:30]))
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}
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bodyLen := totalBodyLen - req.Keylen - elen - extMetaLen
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if bodyLen > MaxBodyLen {
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return m, fmt.Errorf("%d is too big (max %d)",
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bodyLen, MaxBodyLen)
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}
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req.Body = buf[req.Keylen+elen : req.Keylen+elen+bodyLen]
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req.ExtMeta = buf[req.Keylen+elen+bodyLen:]
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}
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}
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return m, err
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}
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func (req *MCRequest) populateFlexBody(r io.Reader, totalBodyLen, elen, framingElen int) (int, error) {
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var m int
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var err error
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if totalBodyLen > 0 {
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buf := make([]byte, totalBodyLen)
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m, err = io.ReadFull(r, buf)
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if err != nil {
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return m, err
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}
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err = req.populateFlexBodyInternal(buf, totalBodyLen, elen, framingElen)
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}
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return m, err
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}
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func (req *MCRequest) populateFlexBodyInternal(buf []byte, totalBodyLen, elen, framingElen int) error {
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var halfByteOffset bool
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var err error
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if framingElen > 0 {
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var objs []FrameInfo
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objs, err, halfByteOffset = parseFrameInfoObjects(buf, framingElen)
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if err != nil {
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return err
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}
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req.FramingExtras = objs
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}
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err = req.populateFlexBodyAfterFrames(buf, totalBodyLen, elen, framingElen, halfByteOffset)
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if err != nil {
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return err
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}
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return nil
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}
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func (req *MCRequest) populateFlexBodyAfterFrames(buf []byte, totalBodyLen, elen, framingElen int, halfByteOffset bool) error {
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var idxCursor int = framingElen
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if req.Opcode >= TAP_MUTATION && req.Opcode <= TAP_CHECKPOINT_END && len(buf[idxCursor:]) > 1 {
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// In these commands there is "engine private"
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// data at the end of the extras. The first 2
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// bytes of extra data give its length.
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if !halfByteOffset {
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elen += int(binary.BigEndian.Uint16(buf[idxCursor:]))
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} else {
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// 0 1 2 3 4 .... 19 20 21 22 ... 32
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// ^-----^ ^-------^ ^------------^
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// offset data do not care
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var buffer uint32 = binary.BigEndian.Uint32(buf[idxCursor:])
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buffer &= 0xffff000
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elen += int(buffer >> 12)
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}
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}
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// Get the extras
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if !halfByteOffset {
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req.Extras = buf[idxCursor : idxCursor+elen]
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} else {
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preShift := buf[idxCursor : idxCursor+elen+1]
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req.Extras = ShiftByteSliceLeft4Bits(preShift)
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}
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idxCursor += elen
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// Get the Key
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if !halfByteOffset {
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req.Key = buf[idxCursor : idxCursor+req.Keylen]
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} else {
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preShift := buf[idxCursor : idxCursor+req.Keylen+1]
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req.Key = ShiftByteSliceLeft4Bits(preShift)
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}
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idxCursor += req.Keylen
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// get the length of extended metadata
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extMetaLen := 0
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if elen > 29 {
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extMetaLen = int(binary.BigEndian.Uint16(req.Extras[28:30]))
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}
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idxCursor += extMetaLen
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bodyLen := totalBodyLen - req.Keylen - elen - extMetaLen - framingElen
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if bodyLen > MaxBodyLen {
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return fmt.Errorf("%d is too big (max %d)",
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bodyLen, MaxBodyLen)
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}
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if !halfByteOffset {
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req.Body = buf[idxCursor : idxCursor+bodyLen]
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idxCursor += bodyLen
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} else {
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preShift := buf[idxCursor : idxCursor+bodyLen+1]
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req.Body = ShiftByteSliceLeft4Bits(preShift)
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idxCursor += bodyLen
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}
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if extMetaLen > 0 {
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if !halfByteOffset {
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req.ExtMeta = buf[idxCursor:]
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} else {
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preShift := buf[idxCursor:]
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req.ExtMeta = ShiftByteSliceLeft4Bits(preShift)
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}
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}
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return nil
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}
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// Receive will fill this MCRequest with the data from a reader.
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func (req *MCRequest) Receive(r io.Reader, hdrBytes []byte) (int, error) {
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if len(hdrBytes) < HDR_LEN {
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hdrBytes = []byte{
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0}
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}
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n, err := io.ReadFull(r, hdrBytes)
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if err != nil {
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fmt.Printf("Err %v\n", err)
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return n, err
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}
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switch hdrBytes[0] {
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case RES_MAGIC:
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fallthrough
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case REQ_MAGIC:
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elen, totalBodyLen := req.receiveRegHeader(hdrBytes)
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bodyRead, err := req.populateRegularBody(r, totalBodyLen, elen)
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return n + bodyRead, err
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case FLEX_MAGIC:
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elen, totalBodyLen, framingElen := req.receiveFlexibleFramingHeader(hdrBytes)
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bodyRead, err := req.populateFlexBody(r, totalBodyLen, elen, framingElen)
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return n + bodyRead, err
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default:
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return n, fmt.Errorf("bad magic: 0x%02x", hdrBytes[0])
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}
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}
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