swarm/storage/feed: Renamed package

swarm/storage/feed/update.go

@@ -0,0 +1,132 @@
+// 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 feed
+
+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            // Feed 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 feed 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
+}