status-go/waku/mailserver_response.go

159 lines
4.6 KiB
Go

// Copyright 2019 The Waku Library Authors.
//
// The Waku 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 Waku library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty off
// 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 Waku library. If not, see <http://www.gnu.org/licenses/>.
//
// This software uses the go-ethereum library, which is licensed
// under the GNU Lesser General Public Library, version 3 or any later.
package waku
import (
"bytes"
"errors"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/p2p/enode"
)
const (
mailServerFailedPayloadPrefix = "ERROR="
cursorSize = 36
)
func invalidResponseSizeError(size int) error {
return fmt.Errorf("unexpected payload size: %d", size)
}
// CreateMailServerRequestCompletedPayload creates a payload representing
// a successful request to mailserver
func CreateMailServerRequestCompletedPayload(requestID, lastEnvelopeHash common.Hash, cursor []byte) []byte {
payload := make([]byte, len(requestID))
copy(payload, requestID[:])
payload = append(payload, lastEnvelopeHash[:]...)
payload = append(payload, cursor...)
return payload
}
// CreateMailServerRequestFailedPayload creates a payload representing
// a failed request to a mailserver
func CreateMailServerRequestFailedPayload(requestID common.Hash, err error) []byte {
payload := []byte(mailServerFailedPayloadPrefix)
payload = append(payload, requestID[:]...)
payload = append(payload, []byte(err.Error())...)
return payload
}
// CreateMailServerEvent returns EnvelopeEvent with correct data
// if payload corresponds to any of the know mailserver events:
// * request completed successfully
// * request failed
// If the payload is unknown/unparseable, it returns `nil`
func CreateMailServerEvent(nodeID enode.ID, payload []byte) (*EnvelopeEvent, error) {
if len(payload) < common.HashLength {
return nil, invalidResponseSizeError(len(payload))
}
event, err := tryCreateMailServerRequestFailedEvent(nodeID, payload)
if err != nil {
return nil, err
} else if event != nil {
return event, nil
}
return tryCreateMailServerRequestCompletedEvent(nodeID, payload)
}
func tryCreateMailServerRequestFailedEvent(nodeID enode.ID, payload []byte) (*EnvelopeEvent, error) {
if len(payload) < common.HashLength+len(mailServerFailedPayloadPrefix) {
return nil, nil
}
prefix, remainder := extractPrefix(payload, len(mailServerFailedPayloadPrefix))
if !bytes.Equal(prefix, []byte(mailServerFailedPayloadPrefix)) {
return nil, nil
}
var (
requestID common.Hash
errorMsg string
)
requestID, remainder = extractHash(remainder)
errorMsg = string(remainder)
event := EnvelopeEvent{
Peer: nodeID,
Hash: requestID,
Event: EventMailServerRequestCompleted,
Data: &MailServerResponse{
Error: errors.New(errorMsg),
},
}
return &event, nil
}
func tryCreateMailServerRequestCompletedEvent(nodeID enode.ID, payload []byte) (*EnvelopeEvent, error) {
// check if payload is
// - requestID or
// - requestID + lastEnvelopeHash or
// - requestID + lastEnvelopeHash + cursor
// requestID is the hash of the request envelope.
// lastEnvelopeHash is the last envelope sent by the mail server
// cursor is the db key, 36 bytes: 4 for the timestamp + 32 for the envelope hash.
if len(payload) > common.HashLength*2+cursorSize {
return nil, invalidResponseSizeError(len(payload))
}
var (
requestID common.Hash
lastEnvelopeHash common.Hash
cursor []byte
)
requestID, remainder := extractHash(payload)
if len(remainder) >= common.HashLength {
lastEnvelopeHash, remainder = extractHash(remainder)
}
if len(remainder) >= cursorSize {
cursor = remainder
}
event := EnvelopeEvent{
Peer: nodeID,
Hash: requestID,
Event: EventMailServerRequestCompleted,
Data: &MailServerResponse{
LastEnvelopeHash: lastEnvelopeHash,
Cursor: cursor,
},
}
return &event, nil
}
func extractHash(payload []byte) (common.Hash, []byte) {
prefix, remainder := extractPrefix(payload, common.HashLength)
return common.BytesToHash(prefix), remainder
}
func extractPrefix(payload []byte, size int) ([]byte, []byte) {
return payload[:size], payload[size:]
}