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forgejo/vendor/github.com/couchbase/gomemcached/mc_req.go

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2019-02-05 17:52:51 +01:00
package gomemcached
import (
"encoding/binary"
"fmt"
"io"
)
// The maximum reasonable body length to expect.
// Anything larger than this will result in an error.
// The current limit, 20MB, is the size limit supported by ep-engine.
var MaxBodyLen = int(20 * 1024 * 1024)
// MCRequest is memcached Request
type MCRequest struct {
// The command being issued
Opcode CommandCode
// The CAS (if applicable, or 0)
Cas uint64
// An opaque value to be returned with this request
Opaque uint32
// The vbucket to which this command belongs
VBucket uint16
// Command extras, key, and body
Extras, Key, Body, ExtMeta []byte
// Datatype identifier
DataType uint8
}
// Size gives the number of bytes this request requires.
func (req *MCRequest) Size() int {
return HDR_LEN + len(req.Extras) + len(req.Key) + len(req.Body) + len(req.ExtMeta)
}
// A debugging string representation of this request
func (req MCRequest) String() string {
return fmt.Sprintf("{MCRequest opcode=%s, bodylen=%d, key='%s'}",
req.Opcode, len(req.Body), req.Key)
}
func (req *MCRequest) fillHeaderBytes(data []byte) int {
pos := 0
data[pos] = REQ_MAGIC
pos++
data[pos] = byte(req.Opcode)
pos++
binary.BigEndian.PutUint16(data[pos:pos+2],
uint16(len(req.Key)))
pos += 2
// 4
data[pos] = byte(len(req.Extras))
pos++
// Data type
if req.DataType != 0 {
data[pos] = byte(req.DataType)
}
pos++
binary.BigEndian.PutUint16(data[pos:pos+2], req.VBucket)
pos += 2
// 8
binary.BigEndian.PutUint32(data[pos:pos+4],
uint32(len(req.Body)+len(req.Key)+len(req.Extras)+len(req.ExtMeta)))
pos += 4
// 12
binary.BigEndian.PutUint32(data[pos:pos+4], req.Opaque)
pos += 4
// 16
if req.Cas != 0 {
binary.BigEndian.PutUint64(data[pos:pos+8], req.Cas)
}
pos += 8
if len(req.Extras) > 0 {
copy(data[pos:pos+len(req.Extras)], req.Extras)
pos += len(req.Extras)
}
if len(req.Key) > 0 {
copy(data[pos:pos+len(req.Key)], req.Key)
pos += len(req.Key)
}
return pos
}
// HeaderBytes will return the wire representation of the request header
// (with the extras and key).
func (req *MCRequest) HeaderBytes() []byte {
data := make([]byte, HDR_LEN+len(req.Extras)+len(req.Key))
req.fillHeaderBytes(data)
return data
}
// Bytes will return the wire representation of this request.
func (req *MCRequest) Bytes() []byte {
data := make([]byte, req.Size())
pos := req.fillHeaderBytes(data)
if len(req.Body) > 0 {
copy(data[pos:pos+len(req.Body)], req.Body)
}
if len(req.ExtMeta) > 0 {
copy(data[pos+len(req.Body):pos+len(req.Body)+len(req.ExtMeta)], req.ExtMeta)
}
return data
}
// Transmit will send this request message across a writer.
func (req *MCRequest) Transmit(w io.Writer) (n int, err error) {
if len(req.Body) < 128 {
n, err = w.Write(req.Bytes())
} else {
n, err = w.Write(req.HeaderBytes())
if err == nil {
m := 0
m, err = w.Write(req.Body)
n += m
}
}
return
}
// Receive will fill this MCRequest with the data from a reader.
func (req *MCRequest) Receive(r io.Reader, hdrBytes []byte) (int, error) {
if len(hdrBytes) < HDR_LEN {
hdrBytes = []byte{
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0}
}
n, err := io.ReadFull(r, hdrBytes)
if err != nil {
return n, err
}
if hdrBytes[0] != RES_MAGIC && hdrBytes[0] != REQ_MAGIC {
return n, fmt.Errorf("bad magic: 0x%02x", hdrBytes[0])
}
klen := int(binary.BigEndian.Uint16(hdrBytes[2:]))
elen := int(hdrBytes[4])
// Data type at 5
req.DataType = uint8(hdrBytes[5])
req.Opcode = CommandCode(hdrBytes[1])
// Vbucket at 6:7
req.VBucket = binary.BigEndian.Uint16(hdrBytes[6:])
totalBodyLen := int(binary.BigEndian.Uint32(hdrBytes[8:]))
req.Opaque = binary.BigEndian.Uint32(hdrBytes[12:])
req.Cas = binary.BigEndian.Uint64(hdrBytes[16:])
if totalBodyLen > 0 {
buf := make([]byte, totalBodyLen)
m, err := io.ReadFull(r, buf)
n += m
if err == nil {
if req.Opcode >= TAP_MUTATION &&
req.Opcode <= TAP_CHECKPOINT_END &&
len(buf) > 1 {
// In these commands there is "engine private"
// data at the end of the extras. The first 2
// bytes of extra data give its length.
elen += int(binary.BigEndian.Uint16(buf))
}
req.Extras = buf[0:elen]
req.Key = buf[elen : klen+elen]
// get the length of extended metadata
extMetaLen := 0
if elen > 29 {
extMetaLen = int(binary.BigEndian.Uint16(req.Extras[28:30]))
}
bodyLen := totalBodyLen - klen - elen - extMetaLen
if bodyLen > MaxBodyLen {
return n, fmt.Errorf("%d is too big (max %d)",
bodyLen, MaxBodyLen)
}
req.Body = buf[klen+elen : klen+elen+bodyLen]
req.ExtMeta = buf[klen+elen+bodyLen:]
}
}
return n, err
}