133 lines
4.4 KiB
Go
133 lines
4.4 KiB
Go
// Copyright 2018 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package mru
|
|
|
|
import (
|
|
"fmt"
|
|
"strconv"
|
|
|
|
"github.com/ethereum/go-ethereum/swarm/chunk"
|
|
)
|
|
|
|
// ProtocolVersion defines the current version of the protocol that will be included in each update message
|
|
const ProtocolVersion uint8 = 0
|
|
|
|
const headerLength = 8
|
|
|
|
// Header defines a update message header including a protocol version byte
|
|
type Header struct {
|
|
Version uint8 // Protocol version
|
|
Padding [headerLength - 1]uint8 // reserved for future use
|
|
}
|
|
|
|
// Update encapsulates the information sent as part of a feed update
|
|
type Update struct {
|
|
Header Header //
|
|
ID // Resource update identifying information
|
|
data []byte // actual data payload
|
|
}
|
|
|
|
const minimumUpdateDataLength = idLength + headerLength + 1
|
|
const maxUpdateDataLength = chunk.DefaultSize - signatureLength - idLength - headerLength
|
|
|
|
// binaryPut serializes the feed update information into the given slice
|
|
func (r *Update) binaryPut(serializedData []byte) error {
|
|
datalength := len(r.data)
|
|
if datalength == 0 {
|
|
return NewError(ErrInvalidValue, "a feed update must contain data")
|
|
}
|
|
|
|
if datalength > maxUpdateDataLength {
|
|
return NewErrorf(ErrInvalidValue, "feed update data is too big (length=%d). Max length=%d", datalength, maxUpdateDataLength)
|
|
}
|
|
|
|
if len(serializedData) != r.binaryLength() {
|
|
return NewErrorf(ErrInvalidValue, "slice passed to putBinary must be of exact size. Expected %d bytes", r.binaryLength())
|
|
}
|
|
|
|
var cursor int
|
|
// serialize Header
|
|
serializedData[cursor] = r.Header.Version
|
|
copy(serializedData[cursor+1:headerLength], r.Header.Padding[:headerLength-1])
|
|
cursor += headerLength
|
|
|
|
// serialize ID
|
|
if err := r.ID.binaryPut(serializedData[cursor : cursor+idLength]); err != nil {
|
|
return err
|
|
}
|
|
cursor += idLength
|
|
|
|
// add the data
|
|
copy(serializedData[cursor:], r.data)
|
|
cursor += datalength
|
|
|
|
return nil
|
|
}
|
|
|
|
// binaryLength returns the expected number of bytes this structure will take to encode
|
|
func (r *Update) binaryLength() int {
|
|
return idLength + headerLength + len(r.data)
|
|
}
|
|
|
|
// binaryGet populates this instance from the information contained in the passed byte slice
|
|
func (r *Update) binaryGet(serializedData []byte) error {
|
|
if len(serializedData) < minimumUpdateDataLength {
|
|
return NewErrorf(ErrNothingToReturn, "chunk less than %d bytes cannot be a resource update chunk", minimumUpdateDataLength)
|
|
}
|
|
dataLength := len(serializedData) - idLength - headerLength
|
|
// at this point we can be satisfied that we have the correct data length to read
|
|
|
|
var cursor int
|
|
|
|
// deserialize Header
|
|
r.Header.Version = serializedData[cursor] // extract the protocol version
|
|
copy(r.Header.Padding[:headerLength-1], serializedData[cursor+1:headerLength]) // extract the padding
|
|
cursor += headerLength
|
|
|
|
if err := r.ID.binaryGet(serializedData[cursor : cursor+idLength]); err != nil {
|
|
return err
|
|
}
|
|
cursor += idLength
|
|
|
|
data := serializedData[cursor : cursor+dataLength]
|
|
cursor += dataLength
|
|
|
|
// now that all checks have passed, copy data into structure
|
|
r.data = make([]byte, dataLength)
|
|
copy(r.data, data)
|
|
|
|
return nil
|
|
|
|
}
|
|
|
|
// FromValues deserializes this instance from a string key-value store
|
|
// useful to parse query strings
|
|
func (r *Update) FromValues(values Values, data []byte) error {
|
|
r.data = data
|
|
version, _ := strconv.ParseUint(values.Get("protocolVersion"), 10, 32)
|
|
r.Header.Version = uint8(version)
|
|
return r.ID.FromValues(values)
|
|
}
|
|
|
|
// AppendValues serializes this structure into the provided string key-value store
|
|
// useful to build query strings
|
|
func (r *Update) AppendValues(values Values) []byte {
|
|
r.ID.AppendValues(values)
|
|
values.Set("protocolVersion", fmt.Sprintf("%d", r.Header.Version))
|
|
return r.data
|
|
}
|