Add vote-validator tool. (#335)

vote-validator is a tool for VSP admins to verify that their vspd deployment
is voting correctly according to user preferences.

.gitignore

@@ -3,6 +3,13 @@
 ./cmd/vspd/vspd.exe
 ./cmd/vspd/vspd
 
+./vote-validator.exe
+./vote-validator
+./cmd/vote-validator/vote-validator.exe
+./cmd/vote-validator/vote-validator
+
+vote-validator.log
+
 # Testing, profiling, and benchmarking artifacts
 cov.out
 *cpu.out

cmd/vote-validator/README.md

@@ -0,0 +1,23 @@
+# vote-validator
+
+vote-validator is a tool for VSP admins to verify that their vspd deployment
+is voting correctly according to user preferences.
+
+## What it does
+
+1. Retrieve all voted tickets from the provided vspd database file.
+1. Retrieve vote info from dcrdata for every voted ticket.
+1. For the n most recently voted tickets, compare the vote choices recorded
+   on-chain to the vote choices set by the user.
+1. Write details of any discrepancies to a file for further investigation.
+
+## How to run it
+
+Only run vote-validator using a copy of the vspd database backup file.
+Never use a real production database.
+
+vote-validator can be run from the repository root as such:
+
+```no-highlight
+go run ./cmd/vote-validator -n 1000 -f ./vspd.db-backup
+```

cmd/vote-validator/dcrdata.go

@@ -0,0 +1,87 @@
+// Copyright (c) 2022 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/decred/dcrd/rpc/jsonrpc/types/v3"
+)
+
+type txns struct {
+	Transactions []string `json:"transactions"`
+}
+
+type txInputID struct {
+	Hash  string `json:"hash"`
+	Index uint32 `json:"vin_index"`
+}
+
+type vout struct {
+	Value               float64                  `json:"value"`
+	N                   uint32                   `json:"n"`
+	Version             uint16                   `json:"version"`
+	ScriptPubKeyDecoded types.ScriptPubKeyResult `json:"scriptPubKey"`
+	Spend               *txInputID               `json:"spend"`
+}
+
+type tx struct {
+	TxID          string      `json:"txid"`
+	Size          int32       `json:"size"`
+	Version       int32       `json:"version"`
+	Locktime      uint32      `json:"locktime"`
+	Expiry        uint32      `json:"expiry"`
+	Vin           []types.Vin `json:"vin"`
+	Vout          []vout      `json:"vout"`
+	Confirmations int64       `json:"confirmations"`
+}
+
+type dcrdataClient struct {
+	URL string
+}
+
+func (d *dcrdataClient) txns(txnHashes []string, spends bool) ([]tx, error) {
+	jsonData, err := json.Marshal(txns{
+		Transactions: txnHashes,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	url := fmt.Sprintf("%s/api/txs?spends=%t", d.URL, spends)
+	request, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
+	if err != nil {
+		return nil, err
+	}
+	request.Header.Set("Content-Type", "application/json; charset=UTF-8")
+
+	client := &http.Client{}
+	resp, err := client.Do(request)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("dcrdata response: %v", resp.Status)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var txns []tx
+	err = json.Unmarshal(body, &txns)
+	if err != nil {
+		return nil, err
+	}
+
+	return txns, nil
+}

cmd/vote-validator/main.go

@@ -0,0 +1,250 @@
+// Copyright (c) 2022 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"os"
+	"sort"
+
+	"github.com/decred/dcrd/chaincfg/v3"
+	"github.com/decred/slog"
+	"github.com/jessevdk/go-flags"
+
+	"github.com/decred/vspd/database"
+)
+
+const (
+	logPath = "./vote-validator.log"
+
+	// Send tx hashes to dcrdata in "chunks" to avoid hitting request size limits.
+	chunkSize = 2000
+)
+
+var cfg struct {
+	Testnet      bool   `short:"t" long:"testnet" description:"Run testnet instead of mainnet"`
+	ToCheck      int    `short:"n" long:"tickets_to_check" required:"true" description:"Validate votes of the n most recently voted tickets"`
+	DatabaseFile string `short:"f" long:"database_file" required:"true" description:"Full path of database file"`
+}
+
+type votedTicket struct {
+	// From vspd db.
+	ticket database.Ticket
+	// From dcrdata.
+	voteHeight  uint32
+	voteVersion uint32
+	vote        map[string]string
+}
+
+func main() {
+	// Run until an exit code is returned.
+	os.Exit(run())
+}
+
+func run() int {
+	// Load config, display help if requested.
+	_, err := flags.Parse(&cfg)
+	if err != nil {
+		var e *flags.Error
+		if errors.As(err, &e) {
+			if e.Type == flags.ErrHelp {
+				return 0
+			}
+		}
+		return 1
+	}
+
+	var dcrdata *dcrdataClient
+	var params *chaincfg.Params
+	if cfg.Testnet {
+		dcrdata = &dcrdataClient{URL: "https://testnet.dcrdata.org"}
+		params = chaincfg.TestNet3Params()
+	} else {
+		dcrdata = &dcrdataClient{URL: "https://explorer.dcrdata.org"}
+		params = chaincfg.MainNetParams()
+	}
+
+	// Get the latest vote version. Any votes which don't match this version
+	// will be ignored.
+	var latestVoteVersion uint32
+	for version := range params.Deployments {
+		if version > latestVoteVersion {
+			latestVoteVersion = version
+		}
+	}
+
+	// Open database.
+	log := slog.NewBackend(os.Stdout).Logger("")
+	vdb, err := database.Open(cfg.DatabaseFile, log, 999)
+	if err != nil {
+		log.Error(err)
+		return 1
+	}
+
+	// Get all voted tickets from database.
+	dbTickets, err := vdb.GetVotedTickets()
+	if err != nil {
+		log.Error(err)
+		return 1
+	}
+
+	numTickets := len(dbTickets)
+	log.Infof("Database has %d voted tickets", numTickets)
+
+	// A bit of pre-processing for later:
+	//   - Store the tickets in a map using their hash as the key. This makes
+	//     it easier to reference them later.
+	//   - Create an array of all hashes. This can easily be sliced into
+	//     "chunks" and sent to dcrdata.
+
+	ticketMap := make(map[string]*votedTicket, numTickets)
+	ticketHashes := make([]string, 0)
+	for _, t := range dbTickets {
+		ticketMap[t.Hash] = &votedTicket{ticket: t}
+		ticketHashes = append(ticketHashes, t.Hash)
+	}
+
+	// Use dcrdata to get spender info for voted tickets (dcrd can't do this).
+	log.Infof("Getting vote info from %s", dcrdata.URL)
+	for i := 0; i < numTickets; i += chunkSize {
+		end := i + chunkSize
+		if end > numTickets {
+			end = numTickets
+		}
+
+		// Get the tx info for each ticket.
+		ticketTxns, err := dcrdata.txns(ticketHashes[i:end], true)
+		if err != nil {
+			log.Error(err)
+			return 1
+		}
+
+		spenderHashes := make([]string, 0)
+		mapSpenderToTicket := make(map[string]string, len(ticketTxns))
+		for _, txn := range ticketTxns {
+			spenderHash := txn.Vout[0].Spend.Hash
+			spenderHashes = append(spenderHashes, spenderHash)
+			mapSpenderToTicket[spenderHash] = txn.TxID
+		}
+
+		spenderTxns, err := dcrdata.txns(spenderHashes, false)
+		if err != nil {
+			log.Error(err)
+			return 1
+		}
+
+		for _, tx := range spenderTxns {
+			ticketHash := mapSpenderToTicket[tx.TxID]
+
+			// Extract vote height from vOut[0]
+			vOut0Script, err := hex.DecodeString(tx.Vout[0].ScriptPubKeyDecoded.Hex)
+			if err != nil {
+				log.Error(err)
+				return 1
+			}
+			// dcrd/blockchain/stake/staketx.go - SSGenBlockVotedOn()
+			votedHeight := binary.LittleEndian.Uint32(vOut0Script[34:38])
+
+			// Extract vote version and votebits from vOut[1]
+			vOut1Script, err := hex.DecodeString(tx.Vout[1].ScriptPubKeyDecoded.Hex)
+			if err != nil {
+				log.Error(err)
+				return 1
+			}
+			// dcrd/blockchain/stake/staketx.go - SSGenVersion()
+			voteVersion := binary.LittleEndian.Uint32(vOut1Script[4:8])
+
+			// dcrd/blockchain/stake/staketx.go - SSGenVoteBits()
+			votebits := binary.LittleEndian.Uint16(vOut1Script[2:4])
+
+			// Get the recorded on-chain votes for this ticket.
+			actualVote := make(map[string]string)
+			agendas := params.Deployments[latestVoteVersion]
+			for _, agenda := range agendas {
+				for _, choice := range agenda.Vote.Choices {
+					if votebits&agenda.Vote.Mask == choice.Bits {
+						actualVote[agenda.Vote.Id] = choice.Id
+					}
+				}
+			}
+
+			ticketMap[ticketHash].voteHeight = votedHeight
+			ticketMap[ticketHash].voteVersion = voteVersion
+			ticketMap[ticketHash].vote = actualVote
+		}
+
+		log.Infof(" %6d of %d (%0.2f%%)", end, numTickets, float32(end)/float32(numTickets)*100)
+	}
+
+	// Convert ticketMap into a slice so that it can be sorted.
+	sorted := make([]*votedTicket, 0)
+	for _, ticket := range ticketMap {
+		sorted = append(sorted, ticket)
+	}
+
+	// Sort tickets by vote height
+	sort.Slice(sorted, func(i, j int) bool {
+		return sorted[i].voteHeight > sorted[j].voteHeight
+	})
+
+	// Do the checks.
+	results := &results{
+		badVotes:      make([]*votedTicket, 0),
+		noPreferences: make([]*votedTicket, 0),
+		wrongVersion:  make([]*votedTicket, 0),
+	}
+
+	for _, t := range sorted[0:cfg.ToCheck] {
+
+		if t.voteVersion != latestVoteVersion {
+			results.wrongVersion = append(results.wrongVersion, t)
+			continue
+		}
+
+		// Get the vote preferences requested by the user.
+		requestedVote := t.ticket.VoteChoices
+
+		if len(requestedVote) == 0 {
+			results.noPreferences = append(results.noPreferences, t)
+		}
+
+		badVote := false
+		for agenda, actualChoice := range t.vote {
+			reqChoice, ok := requestedVote[agenda]
+			// If no choice set, should be abstain.
+			if !ok {
+				reqChoice = "abstain"
+			}
+
+			if actualChoice != reqChoice {
+				badVote = true
+			}
+		}
+
+		if badVote {
+			results.badVotes = append(results.badVotes, t)
+		}
+	}
+
+	log.Infof("")
+	log.Infof("Checked %d most recently voted tickets", cfg.ToCheck)
+	log.Infof(" %6d tickets had incorrect votes", len(results.badVotes))
+	log.Infof(" %6d tickets not checked due to wrong vote version", len(results.wrongVersion))
+	log.Infof(" %6d tickets had no voting preferences set by user", len(results.noPreferences))
+
+	written, err := results.writeFile(logPath)
+	if err != nil {
+		log.Errorf("Failed to write log file: %v", err)
+		return 1
+	}
+	if written {
+		log.Infof("")
+		log.Infof("Detailed information written to %s", logPath)
+	}
+
+	return 0
+}

cmd/vote-validator/results.go

@@ -0,0 +1,79 @@
+// Copyright (c) 2022 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+type results struct {
+	badVotes      []*votedTicket
+	noPreferences []*votedTicket
+	wrongVersion  []*votedTicket
+}
+
+func (r *results) writeFile(path string) (bool, error) {
+
+	if len(r.badVotes) == 0 &&
+		len(r.noPreferences) == 0 &&
+		len(r.wrongVersion) == 0 {
+		return false, nil
+	}
+
+	// Open a log file.
+	f, err := os.Create(path)
+	if err != nil {
+		return false, fmt.Errorf("opening log file failed: %w", err)
+	}
+
+	write := func(f *os.File, str string, a ...any) {
+		_, err := f.WriteString(fmt.Sprintf(str+"\n", a...))
+		if err != nil {
+			f.Close()
+			panic(fmt.Sprintf("writing to log file failed: %v", err))
+		}
+	}
+
+	if len(r.badVotes) > 0 {
+		write(f, "Tickets with bad votes:")
+		for _, t := range r.badVotes {
+			write(f,
+				"Hash: %s VoteHeight: %d ExpectedVote: %v ActualVote: %v",
+				t.ticket.Hash, t.voteHeight, t.ticket.VoteChoices, t.vote,
+			)
+		}
+		write(f, "\n")
+	}
+
+	if len(r.wrongVersion) > 0 {
+		write(f, "Tickets with the wrong vote version:")
+		for _, t := range r.wrongVersion {
+			write(f,
+				"Hash: %s",
+				t.ticket.Hash,
+			)
+		}
+		write(f, "\n")
+	}
+
+	if len(r.noPreferences) > 0 {
+		write(f, "Tickets with no user set vote preferences:")
+		for _, t := range r.noPreferences {
+			write(f,
+				"Hash: %s",
+				t.ticket.Hash,
+			)
+		}
+		write(f, "\n")
+	}
+
+	err = f.Close()
+	if err != nil {
+		return false, fmt.Errorf("closing log file failed: %w", err)
+	}
+
+	return true, nil
+}

database/ticket.go

@@ -383,6 +383,13 @@ func (vdb *VspDatabase) GetVotableTickets() ([]Ticket, error) {
 	})
 }
 
+// GetVotedTickets returns tickets with a confirmed fee tx and outcome == voted.
+func (vdb *VspDatabase) GetVotedTickets() ([]Ticket, error) {
+	return vdb.filterTickets(func(t *bolt.Bucket) bool {
+		return FeeStatus(t.Get(feeTxStatusK)) == FeeConfirmed && TicketOutcome(t.Get(outcomeK)) == Voted
+	})
+}
+
 // GetMissingPurchaseHeight returns tickets which are confirmed but do not have
 // a purchase height.
 func (vdb *VspDatabase) GetMissingPurchaseHeight() ([]Ticket, error) {

go.mod

@@ -1,6 +1,6 @@
 module github.com/decred/vspd
 
-go 1.17
+go 1.18
 
 require (
 	decred.org/dcrwallet/v2 v2.0.1