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-rw-r--r--swarm/storage/feeds/update.go132
1 files changed, 132 insertions, 0 deletions
diff --git a/swarm/storage/feeds/update.go b/swarm/storage/feeds/update.go
new file mode 100644
index 000000000..02bd37522
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+++ b/swarm/storage/feeds/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 feeds
+
+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
+}