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// Copyright (C) 2019-2023 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package rpcs
import (
"encoding/base64"
"net/http"
"strconv"
"strings"
"time"
"github.com/gorilla/mux"
"github.com/algorand/go-deadlock"
"github.com/algorand/go-algorand/data/transactions"
"github.com/algorand/go-algorand/logging"
"github.com/algorand/go-algorand/protocol"
"github.com/algorand/go-algorand/util/bloom"
)
// TxService provides a service that allows a remote caller to retrieve missing pending transactions
type TxService struct {
pool PendingTxAggregate
pendingTxGroups [][]transactions.SignedTxn
lastUpdate int64
mu deadlock.RWMutex
genesisID string
log logging.Logger
// limit the amount of data we're going to process on this request.
// the request body should include the bloom filter encoding. This would
// protect the server from calls that include large body requests.
maxRequestBodyLength int64
// cap the response size by stop sending transactions once we reached
// that size. This allows us to optimize the response size
// and prevent sending huge responses. The client could make several
// request to retrieve the remaining trasactions.
responseSizeLimit int
}
const updateInterval = int64(30)
const responseContentType = "application/x-algorand-ptx-v1"
// calculate the number of bytes that would be consumed when packing a n-bytes buffer into a base64 buffer.
func base64PaddedSize(n int64) int64 {
return ((n + 2) / 3) * 4
}
func makeTxService(pool PendingTxAggregate, genesisID string, txPoolSize int, responseSizeLimit int) *TxService {
// figure out how many bytes do we expect the bloom filter to be in the worst case scenario.
filterBytes := bloom.BinaryMarshalLength(txPoolSize, bloomFilterFalsePositiveRate)
// since the bloom filter is going to be base64 encoded, account for that as well.
filterPackedBytes := base64PaddedSize(filterBytes)
// The http transport add some additional content to the form ( form keys, separators, etc.)
// we need to account for these if we're trying to match the size in the worst case scenario.
const httpFormPostingOverhead = 13
service := &TxService{
pool: pool,
genesisID: genesisID,
log: logging.Base(),
maxRequestBodyLength: filterPackedBytes + httpFormPostingOverhead,
responseSizeLimit: responseSizeLimit,
}
return service
}
// ServeHTTP returns pending transactions that match a bloom filter
func (txs *TxService) ServeHTTP(response http.ResponseWriter, request *http.Request) {
pathVars := mux.Vars(request)
genesisID, hasGenesisID := pathVars["genesisID"]
if hasGenesisID {
if txs.genesisID != genesisID {
txs.log.Infof("http block bad genesisID mine=%#v theirs=%#v", txs.genesisID, genesisID)
response.WriteHeader(http.StatusBadRequest)
return
}
} else {
txs.log.Debug("http block no genesisID")
response.WriteHeader(http.StatusBadRequest)
return
}
contentTypes := request.Header["Content-Type"]
if len(contentTypes) != 1 {
txs.log.Infof("http request had %d content types headers", len(contentTypes))
response.WriteHeader(http.StatusBadRequest)
return
}
if contentTypes[0] != requestContentType {
txs.log.Infof("http request has an invalid content type : %v", contentTypes[0])
response.WriteHeader(http.StatusBadRequest)
return
}
// limit the request body size to maxRequestBodyLength
request.Body = http.MaxBytesReader(response, request.Body, txs.maxRequestBodyLength)
err := request.ParseForm()
if err != nil {
if strings.Contains(err.Error(), "http: request body too large") {
txs.log.Infof("http.ParseForm fail due to body length exceed max limit size of %d", txs.maxRequestBodyLength)
} else {
txs.log.Infof("http.ParseForm fail: %s", err)
}
response.WriteHeader(http.StatusBadRequest)
return
}
bloomFilterText := request.FormValue("bf")
if len(bloomFilterText) == 0 {
txs.log.Info("no bloom filter arg")
response.WriteHeader(http.StatusBadRequest)
return
}
bfblob, err := base64.URLEncoding.DecodeString(bloomFilterText)
if err != nil {
txs.log.Infof("filter decode fail: %s", err)
response.WriteHeader(http.StatusBadRequest)
return
}
filter, err := bloom.UnmarshalBinary(bfblob)
if err != nil {
txs.log.Infof("filter parse fail: %s", err)
response.WriteHeader(http.StatusBadRequest)
return
}
txns := txs.getFilteredTxns(filter)
txblob := protocol.EncodeReflect(txns)
txs.log.Debugf("sending %d txns in %d bytes", len(txns), len(txblob))
response.Header().Set("Content-Length", strconv.Itoa(len(txblob)))
response.Header().Set("Content-Type", responseContentType)
response.WriteHeader(http.StatusOK)
_, err = response.Write(txblob)
if err != nil {
txs.log.Warn("http block write failed", err)
}
}
func (txs *TxService) getFilteredTxns(bloom *bloom.Filter) (txns []transactions.SignedTxn) {
pendingTxGroups := txs.updateTxCache()
missingTxns := make([]transactions.SignedTxn, 0)
encodedLength := 0
for _, txgroup := range pendingTxGroups {
missing := false
txGroupLength := 0
for _, tx := range txgroup {
id := tx.ID()
if !bloom.Test(id[:]) {
missing = true
}
txGroupLength += tx.GetEncodedLength()
}
if missing {
if encodedLength+txGroupLength > txs.responseSizeLimit {
break
}
for _, tx := range txgroup {
missingTxns = append(missingTxns, tx)
}
encodedLength += txGroupLength
}
}
return missingTxns
}
func (txs *TxService) updateTxCache() (pendingTxGroups [][]transactions.SignedTxn) {
currentUnixTime := time.Now().Unix()
txs.mu.RLock()
if txs.lastUpdate != 0 && txs.lastUpdate+updateInterval >= currentUnixTime {
// no need to update.
pendingTxGroups = txs.pendingTxGroups
txs.mu.RUnlock()
return
}
txs.mu.RUnlock()
txs.mu.Lock()
defer txs.mu.Unlock()
// we need to check again, since we released and took the lock.
if txs.lastUpdate == 0 || txs.lastUpdate+updateInterval < currentUnixTime {
// The txs.pool.PendingTxGroups() function allocates a new array on every call. That means that the old
// array ( if being used ) is still valid. There is no risk of data race here since
// the txs.pendingTxGroups is a slice (hence a pointer to the array) and not the array itself.
txs.pendingTxGroups = txs.pool.PendingTxGroups()
txs.lastUpdate = currentUnixTime
}
return txs.pendingTxGroups
}
// TxServiceHTTPPath is the URL path to sync pending transactions from
const TxServiceHTTPPath = "/v1/{genesisID}/txsync"
// RegisterTxService creates a TxService around the provider transaction pool and registers it for RPC with the provided Registrar
func RegisterTxService(pool PendingTxAggregate, registrar Registrar, genesisID string, txPoolSize int, responseSizeLimit int) {
service := makeTxService(pool, genesisID, txPoolSize, responseSizeLimit)
registrar.RegisterHTTPHandler(TxServiceHTTPPath, service)
}
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