Split voting wallet and fee wallet clients (#45)

README.md

@@ -4,17 +4,54 @@
 [![ISC License](https://img.shields.io/badge/license-ISC-blue.svg)](http://copyfree.org)
 [![Go Report Card](https://goreportcard.com/badge/github.com/jholdstock/dcrvsp)](https://goreportcard.com/report/github.com/jholdstock/dcrvsp)
 
-## Design decisions
+## Overview
 
-- [gin-gonic](https://github.com/gin-gonic/gin) webserver for both front-end and API.
+User purchases a ticket, doesnt need any special conditions, indistinguishable
+from solo ticket. User can then choose to use a VSP on a per-ticket basis. Once
+the ticket is mined, and ideally before it has matured, the user sends the
+ticket details + fee to a VSP, and the VSP will take the fee and vote in return.
+
+## Advantages
+
+### For Administrators
+
+- bbolt db.
+- No stakepoold.
+- Client accountability.
+
+### For Users
+
+- No redeem script to back up.
+- No registration required. No email.
+- Multiple VSPs on a single ticket.
+- Voting preferences per ticket.
+- Server accountability.
+- No address reuse.
+- VSP fees are paid "out of band", rather than being included in the ticket
+  itself. This makes solo tickets and VSP tickets indistinguishable from
+  eachother, enabling VSP users to purchase tickets in the same anonymity set
+  as solo stakers.
+
+## Design Decisions
+
+- [gin-gonic](https://github.com/gin-gonic/gin) webserver.
   - Success responses use HTTP status 200 and a JSON encoded body.
-  - Error responses use either HTTP status 500 or 400, and a JSON encoded error in the body (eg. `{"error":"Description"}')
+  - Error responses use either HTTP status 500 or 400, and a JSON encoded error
+    in the body (eg. `{"error":"Description"}')
 - [bbolt](https://github.com/etcd-io/bbolt) k/v database.
   - Tickets are stored in a single bucket, using ticket hash as the key and a
     json encoded representation of the ticket as the value.
-- [wsrpc](https://github.com/jrick/wsrpc) for dcrwallet comms.
+- [wsrpc](https://github.com/jrick/wsrpc) for RPC communication between dcrvsp
+  and dcrwallet.
 
-## MVP features
+## Architecture
+
+- Single server running dcrvsp, dcrwallet and dcrd. dcrd requires txindex so
+  `getrawtransaction` can be used.
+- Multiple remote "Voting servers", each running dcrwallet and dcrd. dcrwallet
+  on these servers should be constantly unlocked and have voting enabled.
+
+## MVP Features
 
 - When dcrvsp is started for the first time, it generates a ed25519 keypair and
   stores it in the database. This key is used to sign all API responses, and the
@@ -29,11 +66,12 @@
   - Pay fee (`POST /payFee`)
   - Ticket status (`GET /ticketstatus`)
   - Set voting preferences (`POST /setvotechoices`)
-- A minimal, static, web front-end providing pool stats and basic connection instructions.
+- A minimal, static, web front-end providing pool stats and basic connection
+  instructions.
 - Fees have an expiry period. If the fee is not paid within this period, the
   client must request a new fee. This enables the VSP to alter its fee rate.
 
-## Future features
+## Future Features
 
 - Write database backups to disk periodically.
 - Backup over http.
@@ -41,9 +79,11 @@
 - Accountability for both client and server changes to voting preferences.
 - Consistency checking across connected wallets.
 
-## Notes
+## Backup and Recovery
 
-- dcrd must have transaction index enabled so `getrawtransaction` can be used.
+- Regular backups of bbolt database.
+- Restore requires manual repair of fee wallet. Import xpub into account "fees",
+  and rescan with a very large gap limit.
 
 ## Issue Tracker
 

config.go

@@ -17,35 +17,41 @@ import (
 )
 
 var (
-	defaultListen         = ":3000"
+	defaultListen           = ":3000"
-	defaultLogLevel       = "debug"
+	defaultLogLevel         = "debug"
-	defaultVSPFee         = 0.01
+	defaultVSPFee           = 0.01
-	defaultNetwork        = "testnet"
+	defaultNetwork          = "testnet"
-	defaultHomeDir        = dcrutil.AppDataDir("dcrvsp", false)
+	defaultHomeDir          = dcrutil.AppDataDir("dcrvsp", false)
-	defaultConfigFilename = "dcrvsp.conf"
+	defaultConfigFilename   = "dcrvsp.conf"
-	defaultConfigFile     = filepath.Join(defaultHomeDir, defaultConfigFilename)
+	defaultConfigFile       = filepath.Join(defaultHomeDir, defaultConfigFilename)
-	defaultWalletHost     = "127.0.0.1"
+	defaultFeeWalletHost    = "127.0.0.1"
-	defaultWebServerDebug = false
+	defaultVotingWalletHost = "127.0.0.1"
+	defaultWebServerDebug   = false
 )
 
 // config defines the configuration options for the VSP.
 type config struct {
-	Listen         string  `long:"listen" ini-name:"listen" description:"The ip:port to listen for API requests."`
+	Listen           string  `long:"listen" ini-name:"listen" description:"The ip:port to listen for API requests."`
-	LogLevel       string  `long:"loglevel" ini-name:"loglevel" description:"Logging level." choice:"trace" choice:"debug" choice:"info" choice:"warn" choice:"error" choice:"critical"`
+	LogLevel         string  `long:"loglevel" ini-name:"loglevel" description:"Logging level." choice:"trace" choice:"debug" choice:"info" choice:"warn" choice:"error" choice:"critical"`
-	Network        string  `long:"network" ini-name:"network" description:"Decred network to use." choice:"testnet" choice:"mainnet" choice:"simnet"`
+	Network          string  `long:"network" ini-name:"network" description:"Decred network to use." choice:"testnet" choice:"mainnet" choice:"simnet"`
-	FeeXPub        string  `long:"feexpub" ini-name:"feexpub" description:"Cold wallet xpub used for collecting fees."`
+	FeeXPub          string  `long:"feexpub" ini-name:"feexpub" description:"Cold wallet xpub used for collecting fees."`
-	VSPFee         float64 `long:"vspfee" ini-name:"vspfee" description:"Fee percentage charged for VSP use. eg. 0.01 (1%), 0.05 (5%)."`
+	VSPFee           float64 `long:"vspfee" ini-name:"vspfee" description:"Fee percentage charged for VSP use. eg. 0.01 (1%), 0.05 (5%)."`
-	HomeDir        string  `long:"homedir" ini-name:"homedir" no-ini:"true" description:"Path to application home directory. Used for storing VSP database and logs."`
+	HomeDir          string  `long:"homedir" ini-name:"homedir" no-ini:"true" description:"Path to application home directory. Used for storing VSP database and logs."`
-	ConfigFile     string  `long:"configfile" ini-name:"configfile" no-ini:"true" description:"Path to configuration file."`
+	ConfigFile       string  `long:"configfile" ini-name:"configfile" no-ini:"true" description:"Path to configuration file."`
-	WalletHost     string  `long:"wallethost" ini-name:"wallethost" description:"The ip:port to establish a JSON-RPC connection with dcrwallet."`
+	FeeWalletHost    string  `long:"feewallethost" ini-name:"feewallethost" description:"The ip:port to establish a JSON-RPC connection with fee dcrwallet."`
-	WalletUser     string  `long:"walletuser" ini-name:"walletuser" description:"Username for dcrwallet RPC connections."`
+	FeeWalletUser    string  `long:"feewalletuser" ini-name:"feewalletuser" description:"Username for fee dcrwallet RPC connections."`
-	WalletPass     string  `long:"walletpass" ini-name:"walletpass" description:"Password for dcrwallet RPC connections."`
+	FeeWalletPass    string  `long:"feewalletpass" ini-name:"feewalletpass" description:"Password for fee dcrwallet RPC connections."`
-	WalletCert     string  `long:"walletcert" ini-name:"walletcert" description:"The dcrwallet RPC certificate file."`
+	FeeWalletCert    string  `long:"feewalletcert" ini-name:"feewalletcert" description:"The fee dcrwallet RPC certificate file."`
-	WebServerDebug bool    `long:"webserverdebug" ini-name:"webserverdebug" description:"Enable web server debug mode (verbose logging to terminal and live-reloading templates)."`
+	VotingWalletHost string  `long:"votingwallethost" ini-name:"votingwallethost" description:"The ip:port to establish a JSON-RPC connection with voting dcrwallet."`
+	VotingWalletUser string  `long:"votingwalletuser" ini-name:"votingwalletuser" description:"Username for voting dcrwallet RPC connections."`
+	VotingWalletPass string  `long:"votingwalletpass" ini-name:"votingwalletpass" description:"Password for voting dcrwallet RPC connections."`
+	VotingWalletCert string  `long:"votingwalletcert" ini-name:"votingwalletcert" description:"The voting dcrwallet RPC certificate file."`
+	WebServerDebug   bool    `long:"webserverdebug" ini-name:"webserverdebug" description:"Enable web server debug mode (verbose logging to terminal and live-reloading templates)."`
 
-	dbPath    string
+	dbPath           string
-	netParams *netParams
+	netParams        *netParams
-	dcrwCert  []byte
+	feeWalletCert    []byte
+	votingWalletCert []byte
 }
 
 // fileExists reports whether the named file or directory exists.
@@ -136,14 +142,15 @@ func loadConfig() (*config, error) {
 
 	// Default config.
 	cfg := config{
-		Listen:         defaultListen,
+		Listen:           defaultListen,
-		LogLevel:       defaultLogLevel,
+		LogLevel:         defaultLogLevel,
-		Network:        defaultNetwork,
+		Network:          defaultNetwork,
-		VSPFee:         defaultVSPFee,
+		VSPFee:           defaultVSPFee,
-		HomeDir:        defaultHomeDir,
+		HomeDir:          defaultHomeDir,
-		ConfigFile:     defaultConfigFile,
+		ConfigFile:       defaultConfigFile,
-		WalletHost:     defaultWalletHost,
+		FeeWalletHost:    defaultFeeWalletHost,
-		WebServerDebug: defaultWebServerDebug,
+		VotingWalletHost: defaultVotingWalletHost,
+		WebServerDebug:   defaultWebServerDebug,
 	}
 
 	// Pre-parse the command line options to see if an alternative config
@@ -233,30 +240,53 @@ func loadConfig() (*config, error) {
 		cfg.netParams = &simNetParams
 	}
 
-	// Ensure the dcrwallet RPC username is set.
+	// Ensure the fee dcrwallet RPC username is set.
-	if cfg.WalletUser == "" {
+	if cfg.FeeWalletUser == "" {
-		return nil, errors.New("the walletuser option is not set")
+		return nil, errors.New("the feewalletuser option is not set")
 	}
 
-	// Ensure the dcrwallet RPC password is set.
+	// Ensure the fee dcrwallet RPC password is set.
-	if cfg.WalletPass == "" {
+	if cfg.FeeWalletPass == "" {
-		return nil, errors.New("the walletpass option is not set")
+		return nil, errors.New("the feewalletpass option is not set")
 	}
 
-	// Ensure the dcrwallet RPC cert path is set.
+	// Ensure the fee dcrwallet RPC cert path is set.
-	if cfg.WalletCert == "" {
+	if cfg.FeeWalletCert == "" {
-		return nil, errors.New("the walletcert option is not set")
+		return nil, errors.New("the feewalletcert option is not set")
+	}
+
+	// Load fee dcrwallet RPC certificate.
+	cfg.FeeWalletCert = cleanAndExpandPath(cfg.FeeWalletCert)
+	cfg.feeWalletCert, err = ioutil.ReadFile(cfg.FeeWalletCert)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read fee dcrwallet cert file: %v", err)
+	}
+
+	// Ensure the voting dcrwallet RPC username is set.
+	if cfg.VotingWalletUser == "" {
+		return nil, errors.New("the votingwalletuser option is not set")
+	}
+
+	// Ensure the voting dcrwallet RPC password is set.
+	if cfg.VotingWalletPass == "" {
+		return nil, errors.New("the votingwalletpass option is not set")
+	}
+
+	// Ensure the voting dcrwallet RPC cert path is set.
+	if cfg.VotingWalletCert == "" {
+		return nil, errors.New("the votingwalletcert option is not set")
+	}
+
+	// Load voting dcrwallet RPC certificate.
+	cfg.VotingWalletCert = cleanAndExpandPath(cfg.VotingWalletCert)
+	cfg.votingWalletCert, err = ioutil.ReadFile(cfg.VotingWalletCert)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read voting dcrwallet cert file: %v", err)
 	}
 
 	// Add default port for the active network if there is no port specified.
-	cfg.WalletHost = normalizeAddress(cfg.WalletHost, cfg.netParams.WalletRPCServerPort)
+	cfg.FeeWalletHost = normalizeAddress(cfg.FeeWalletHost, cfg.netParams.WalletRPCServerPort)
-
+	cfg.VotingWalletHost = normalizeAddress(cfg.VotingWalletHost, cfg.netParams.WalletRPCServerPort)
-	// Load dcrwallet RPC certificate.
-	cfg.WalletCert = cleanAndExpandPath(cfg.WalletCert)
-	cfg.dcrwCert, err = ioutil.ReadFile(cfg.WalletCert)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read dcrwallet cert file: %v", err)
-	}
 
 	// Create the data directory.
 	dataDir := filepath.Join(cfg.HomeDir, "data", cfg.netParams.Name)

main.go

@@ -11,7 +11,6 @@ import (
 	"github.com/jholdstock/dcrvsp/database"
 	"github.com/jholdstock/dcrvsp/rpc"
 	"github.com/jholdstock/dcrvsp/webapi"
-	"github.com/jrick/wsrpc/v2"
 )
 
 const (
@@ -59,11 +58,36 @@ func run(ctx context.Context) error {
 		return err
 	}
 
-	// Create dcrwallet RPC client.
+	// Create RPC client for local dcrwallet instance (used for generating fee
-	walletRPC := rpc.Setup(ctx, &shutdownWg, cfg.WalletUser, cfg.WalletPass, cfg.WalletHost, cfg.dcrwCert)
+	// addresses and broadcasting fee transactions).
-	walletClient, err := walletRPC()
+	feeWalletConnect := rpc.Setup(ctx, &shutdownWg, cfg.FeeWalletUser, cfg.FeeWalletPass, cfg.FeeWalletHost, cfg.feeWalletCert)
+	feeWalletConn, err := feeWalletConnect()
 	if err != nil {
-		log.Errorf("dcrwallet RPC error: %v", err)
+		log.Errorf("Fee wallet connection error: %v", err)
+		requestShutdown()
+		shutdownWg.Wait()
+		return err
+	}
+	feeWalletClient, err := rpc.FeeWalletClient(ctx, feeWalletConn)
+	if err != nil {
+		log.Errorf("Fee wallet client error: %v", err)
+		requestShutdown()
+		shutdownWg.Wait()
+		return err
+	}
+
+	// Create RPC client for remote dcrwallet instance (used for voting).
+	votingWalletConnect := rpc.Setup(ctx, &shutdownWg, cfg.VotingWalletUser, cfg.VotingWalletPass, cfg.VotingWalletHost, cfg.votingWalletCert)
+	votingWalletConn, err := votingWalletConnect()
+	if err != nil {
+		log.Errorf("Voting wallet connection error: %v", err)
+		requestShutdown()
+		shutdownWg.Wait()
+		return err
+	}
+	_, err = rpc.VotingWalletClient(ctx, votingWalletConn)
+	if err != nil {
+		log.Errorf("Voting wallet client error: %v", err)
 		requestShutdown()
 		shutdownWg.Wait()
 		return err
@@ -78,7 +102,7 @@ func run(ctx context.Context) error {
 	}
 
 	// Ensure the wallet account for collecting fees exists and matches config.
-	err = setupFeeAccount(ctx, walletClient, cfg.FeeXPub)
+	err = setupFeeAccount(ctx, feeWalletClient, cfg.FeeXPub)
 	if err != nil {
 		log.Errorf("Fee account error: %v", err)
 		requestShutdown()
@@ -95,7 +119,7 @@ func run(ctx context.Context) error {
 		FeeAccountName:       feeAccountName,
 		FeeAddressExpiration: defaultFeeAddressExpiration,
 	}
-	err = webapi.Start(ctx, shutdownRequestChannel, &shutdownWg, cfg.Listen, db, walletRPC, cfg.WebServerDebug, apiCfg)
+	err = webapi.Start(ctx, shutdownRequestChannel, &shutdownWg, cfg.Listen, db, feeWalletConnect, votingWalletConnect, cfg.WebServerDebug, apiCfg)
 	if err != nil {
 		log.Errorf("Failed to initialise webapi: %v", err)
 		requestShutdown()
@@ -109,20 +133,18 @@ func run(ctx context.Context) error {
 	return ctx.Err()
 }
 
-func setupFeeAccount(ctx context.Context, walletClient *wsrpc.Client, feeXpub string) error {
+func setupFeeAccount(ctx context.Context, walletClient *rpc.FeeWalletRPC, feeXpub string) error {
 	// Check if account for fee collection already exists.
-	var accounts map[string]float64
+	accounts, err := walletClient.ListAccounts(ctx)
-	err := walletClient.Call(ctx, "listaccounts", &accounts)
 	if err != nil {
-		return fmt.Errorf("dcrwallet RPC error: %v", err)
+		return fmt.Errorf("ListAccounts error: %v", err)
 	}
 
 	if _, ok := accounts[feeAccountName]; ok {
 		// Account already exists. Check xpub matches xpub from config.
-		var existingXPub string
+		existingXPub, err := walletClient.GetMasterPubKey(ctx, feeAccountName)
-		err = walletClient.Call(ctx, "getmasterpubkey", &existingXPub, feeAccountName)
 		if err != nil {
-			return fmt.Errorf("dcrwallet RPC error: %v", err)
+			return fmt.Errorf("GetMasterPubKey error: %v", err)
 		}
 
 		if existingXPub != feeXpub {
@@ -133,8 +155,8 @@ func setupFeeAccount(ctx context.Context, walletClient *wsrpc.Client, feeXpub st
 
 	} else {
 		// Account does not exist. Create it using xpub from config.
-		if err = walletClient.Call(ctx, "importxpub", nil, feeAccountName, feeXpub); err != nil {
+		if err = walletClient.ImportXPub(ctx, feeAccountName, feeXpub); err != nil {
-			log.Errorf("Failed to import xpub: %v", err)
+			log.Errorf("ImportXPub error: %v", err)
 			return err
 		}
 		log.Debugf("Created new wallet account %q to collect fees", feeAccountName)

rpc/client.go

@@ -4,25 +4,29 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
-	"fmt"
 	"sync"
 
-	wallettypes "decred.org/dcrwallet/rpc/jsonrpc/types"
-	dcrdtypes "github.com/decred/dcrd/rpc/jsonrpc/types/v2"
 	"github.com/jrick/wsrpc/v2"
 )
 
-type Client func() (*wsrpc.Client, error)
+// Caller provides a client interface to perform JSON-RPC remote procedure calls.
+type Caller interface {
+	// Call performs the remote procedure call defined by method and
+	// waits for a response or a broken client connection.
+	// Args provides positional parameters for the call.
+	// Res must be a pointer to a struct, slice, or map type to unmarshal
+	// a result (if any), or nil if no result is needed.
+	Call(ctx context.Context, method string, res interface{}, args ...interface{}) error
+}
 
-const (
+// Connect dials and returns a connected RPC client.
-	requiredWalletVersion = "8.1.0"
+type Connect func() (Caller, error)
-)
 
 // Setup accepts RPC connection details, creates an RPC client, and returns a
 // function which can be called to access the client. The returned function will
 // try to handle any client disconnects by attempting to reconnect, but will
 // return an error if a new connection cannot be established.
-func Setup(ctx context.Context, shutdownWg *sync.WaitGroup, user, pass, addr string, cert []byte) Client {
+func Setup(ctx context.Context, shutdownWg *sync.WaitGroup, user, pass, addr string, cert []byte) Connect {
 
 	// Create TLS options.
 	pool := x509.NewCertPool()
@@ -33,6 +37,8 @@ func Setup(ctx context.Context, shutdownWg *sync.WaitGroup, user, pass, addr str
 	// Create authentication options.
 	authOpt := wsrpc.WithBasicAuth(user, pass)
 
+	fullAddr := "wss://" + addr + "/ws"
+
 	var mu sync.Mutex
 	var c *wsrpc.Client
 
@@ -59,7 +65,7 @@ func Setup(ctx context.Context, shutdownWg *sync.WaitGroup, user, pass, addr str
 		shutdownWg.Done()
 	}()
 
-	return func() (*wsrpc.Client, error) {
+	return func() (Caller, error) {
 		defer mu.Unlock()
 		mu.Lock()
 
@@ -73,45 +79,11 @@ func Setup(ctx context.Context, shutdownWg *sync.WaitGroup, user, pass, addr str
 			}
 		}
 
-		fullAddr := "wss://" + addr + "/ws"
+		var err error
-		c, err := wsrpc.Dial(ctx, fullAddr, tlsOpt, authOpt)
+		c, err = wsrpc.Dial(ctx, fullAddr, tlsOpt, authOpt)
 		if err != nil {
 			return nil, err
 		}
-		log.Infof("Dialed RPC websocket %v", addr)
-
-		// Verify dcrwallet at is at the required api version
-		var verMap map[string]dcrdtypes.VersionResult
-		err = c.Call(ctx, "version", &verMap)
-		if err != nil {
-			c.Close()
-			return nil, fmt.Errorf("wallet %v version failed: %v",
-				addr, err)
-		}
-		walletVersion, exists := verMap["dcrwalletjsonrpcapi"]
-		if !exists {
-			c.Close()
-			return nil, fmt.Errorf("wallet %v version response "+
-				"missing 'dcrwalletjsonrpcapi'", addr)
-		}
-		if walletVersion.VersionString != requiredWalletVersion {
-			c.Close()
-			return nil, fmt.Errorf("wallet %v is not at the "+
-				"proper version: %s != %s", addr,
-				walletVersion.VersionString, requiredWalletVersion)
-		}
-
-		// Verify dcrwallet is voting
-		var walletInfo wallettypes.WalletInfoResult
-		err = c.Call(ctx, "walletinfo", &walletInfo)
-		if err != nil {
-			c.Close()
-			return nil, err
-		}
-		if !walletInfo.Voting || !walletInfo.Unlocked {
-			c.Close()
-			return nil, fmt.Errorf("wallet %s has voting disabled", addr)
-		}
 
 		return c, nil
 	}

rpc/feewallet.go

@@ -0,0 +1,113 @@
+package rpc
+
+import (
+	"context"
+	"fmt"
+
+	wallettypes "decred.org/dcrwallet/rpc/jsonrpc/types"
+	dcrdtypes "github.com/decred/dcrd/rpc/jsonrpc/types/v2"
+)
+
+const (
+	requiredFeeWalletVersion = "8.1.0"
+)
+
+// FeeWalletRPC provides methods for calling dcrwallet JSON-RPCs without exposing the details
+// of JSON encoding.
+type FeeWalletRPC struct {
+	Caller
+}
+
+// FeeWalletClient creates a new WalletRPC client instance from a caller.
+func FeeWalletClient(ctx context.Context, c Caller) (*FeeWalletRPC, error) {
+
+	// Verify dcrwallet is at the required api version.
+	var verMap map[string]dcrdtypes.VersionResult
+	err := c.Call(ctx, "version", &verMap)
+	if err != nil {
+		return nil, fmt.Errorf("version check failed: %v", err)
+	}
+	walletVersion, exists := verMap["dcrwalletjsonrpcapi"]
+	if !exists {
+		return nil, fmt.Errorf("version response missing 'dcrwalletjsonrpcapi'")
+	}
+	if walletVersion.VersionString != requiredFeeWalletVersion {
+		return nil, fmt.Errorf("wrong dcrwallet RPC version: expected %s, got %s",
+			walletVersion.VersionString, requiredFeeWalletVersion)
+	}
+
+	// Verify dcrwallet is connected to dcrd (not SPV).
+	var walletInfo wallettypes.WalletInfoResult
+	err = c.Call(ctx, "walletinfo", &walletInfo)
+	if err != nil {
+		return nil, fmt.Errorf("walletinfo check failed: %v", err)
+	}
+	if !walletInfo.DaemonConnected {
+		return nil, fmt.Errorf("wallet is not connected to dcrd")
+	}
+
+	// TODO: Ensure correct network.
+
+	return &FeeWalletRPC{c}, nil
+}
+
+func (c *FeeWalletRPC) ImportXPub(ctx context.Context, account, xpub string) error {
+	return c.Call(ctx, "importxpub", nil, account, xpub)
+}
+
+func (c *FeeWalletRPC) GetMasterPubKey(ctx context.Context, account string) (string, error) {
+	var pubKey string
+	err := c.Call(ctx, "getmasterpubkey", &pubKey, account)
+	if err != nil {
+		return "", err
+	}
+	return pubKey, nil
+}
+
+func (c *FeeWalletRPC) ListAccounts(ctx context.Context) (map[string]float64, error) {
+	var accounts map[string]float64
+	err := c.Call(ctx, "listaccounts", &accounts)
+	if err != nil {
+		return nil, err
+	}
+	return accounts, nil
+}
+
+func (c *FeeWalletRPC) GetNewAddress(ctx context.Context, account string) (string, error) {
+	var newAddress string
+	err := c.Call(ctx, "getnewaddress", &newAddress, account)
+	if err != nil {
+		return "", err
+	}
+	return newAddress, nil
+}
+
+func (c *FeeWalletRPC) GetBlockHeader(ctx context.Context, blockHash string) (*dcrdtypes.GetBlockHeaderVerboseResult, error) {
+	verbose := true
+	var blockHeader dcrdtypes.GetBlockHeaderVerboseResult
+	err := c.Call(ctx, "getblockheader", &blockHeader, blockHash, verbose)
+	if err != nil {
+		return nil, err
+	}
+	return &blockHeader, nil
+}
+
+func (c *FeeWalletRPC) GetRawTransaction(ctx context.Context, txHash string) (*dcrdtypes.TxRawResult, error) {
+	verbose := 1
+	var resp dcrdtypes.TxRawResult
+	err := c.Call(ctx, "getrawtransaction", &resp, txHash, verbose)
+	if err != nil {
+		return nil, err
+	}
+	return &resp, nil
+}
+
+func (c *FeeWalletRPC) SendRawTransaction(ctx context.Context, txHex string) (string, error) {
+	allowHighFees := false
+	var txHash string
+	err := c.Call(ctx, "sendrawtransaction", &txHash, txHex, allowHighFees)
+	if err != nil {
+		return "", err
+	}
+	return txHash, nil
+}

rpc/votingwallet.go

@@ -0,0 +1,73 @@
+package rpc
+
+import (
+	"context"
+	"fmt"
+
+	wallettypes "decred.org/dcrwallet/rpc/jsonrpc/types"
+	dcrdtypes "github.com/decred/dcrd/rpc/jsonrpc/types/v2"
+)
+
+const (
+	requiredVotingWalletVersion = "8.1.0"
+)
+
+// VotingWalletRPC provides methods for calling dcrwallet JSON-RPCs without exposing the details
+// of JSON encoding.
+type VotingWalletRPC struct {
+	Caller
+}
+
+// VotingWalletClient creates a new VotingWalletRPC client instance from a caller.
+func VotingWalletClient(ctx context.Context, c Caller) (*VotingWalletRPC, error) {
+
+	// Verify dcrwallet is at the required api version.
+	var verMap map[string]dcrdtypes.VersionResult
+	err := c.Call(ctx, "version", &verMap)
+	if err != nil {
+		return nil, fmt.Errorf("version check failed: %v", err)
+	}
+	walletVersion, exists := verMap["dcrwalletjsonrpcapi"]
+	if !exists {
+		return nil, fmt.Errorf("version response missing 'dcrwalletjsonrpcapi'")
+	}
+	if walletVersion.VersionString != requiredVotingWalletVersion {
+		return nil, fmt.Errorf("wrong dcrwallet RPC version: expected %s, got %s",
+			walletVersion.VersionString, requiredVotingWalletVersion)
+	}
+
+	// Verify dcrwallet is voting, unlocked, and is connected to dcrd (not SPV).
+	var walletInfo wallettypes.WalletInfoResult
+	err = c.Call(ctx, "walletinfo", &walletInfo)
+	if err != nil {
+		return nil, fmt.Errorf("walletinfo check failed: %v", err)
+	}
+	if !walletInfo.Voting {
+		return nil, fmt.Errorf("wallet has voting disabled")
+	}
+	if !walletInfo.Unlocked {
+		return nil, fmt.Errorf("wallet is not unlocked")
+	}
+	if !walletInfo.DaemonConnected {
+		return nil, fmt.Errorf("wallet is not connected to dcrd")
+	}
+
+	// TODO: Ensure correct network.
+
+	return &VotingWalletRPC{c}, nil
+}
+
+func (c *VotingWalletRPC) AddTransaction(ctx context.Context, blockHash, txHex string) error {
+	return c.Call(ctx, "addtransaction", nil, blockHash, txHex)
+}
+
+func (c *VotingWalletRPC) ImportPrivKey(ctx context.Context, votingWIF string) error {
+	label := "imported"
+	rescan := false
+	scanFrom := 0
+	return c.Call(ctx, "importprivkey", nil, votingWIF, label, rescan, scanFrom)
+}
+
+func (c *VotingWalletRPC) SetVoteChoice(ctx context.Context, agenda, choice, ticketHash string) error {
+	return c.Call(ctx, "setvotechoice", nil, agenda, choice, ticketHash)
+}

webapi/getfeeaddress.go

@@ -11,10 +11,10 @@ import (
 	"github.com/decred/dcrd/blockchain/stake/v3"
 	"github.com/decred/dcrd/chaincfg/chainhash"
 	"github.com/decred/dcrd/dcrutil/v3"
-	dcrdtypes "github.com/decred/dcrd/rpc/jsonrpc/types/v2"
 	"github.com/decred/dcrd/wire"
 	"github.com/gin-gonic/gin"
 	"github.com/jholdstock/dcrvsp/database"
+	"github.com/jholdstock/dcrvsp/rpc"
 )
 
 // feeAddress is the handler for "POST /feeaddress"
@@ -82,17 +82,21 @@ func feeAddress(c *gin.Context) {
 		return
 	}
 
-	walletClient, err := walletRPC()
+	fWalletConn, err := feeWalletConnect()
 	if err != nil {
-		log.Errorf("Failed to dial dcrwallet RPC: %v", err)
+		log.Errorf("Fee wallet connection error: %v", err)
+		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
+		return
+	}
+	ctx := c.Request.Context()
+	fWalletClient, err := rpc.FeeWalletClient(ctx, fWalletConn)
+	if err != nil {
+		log.Errorf("Fee wallet client error: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
 
-	ctx := c.Request.Context()
+	resp, err := fWalletClient.GetRawTransaction(ctx, txHash.String())
-
-	var resp dcrdtypes.TxRawResult
-	err = walletClient.Call(ctx, "getrawtransaction", &resp, txHash.String(), 1)
 	if err != nil {
 		log.Warnf("Could not retrieve tx %s for %s: %v", txHash, c.ClientIP(), err)
 		sendErrorResponse("unknown transaction", http.StatusBadRequest, c)
@@ -153,16 +157,15 @@ func feeAddress(c *gin.Context) {
 	// get blockheight and sdiff which is required by
 	// txrules.StakePoolTicketFee, and store them in the database
 	// for processing by payfee
-	var blockHeader dcrdtypes.GetBlockHeaderVerboseResult
+	blockHeader, err := fWalletClient.GetBlockHeader(ctx, resp.BlockHash)
-	err = walletClient.Call(ctx, "getblockheader", &blockHeader, resp.BlockHash, true)
 	if err != nil {
 		log.Errorf("GetBlockHeader error: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
 
-	var newAddress string
+	// TODO: Generate this within dcrvsp without an RPC call?
-	err = walletClient.Call(ctx, "getnewaddress", &newAddress, "fees")
+	newAddress, err := fWalletClient.GetNewAddress(ctx, cfg.FeeAccountName)
 	if err != nil {
 		log.Errorf("GetNewAddress error: %v", err)
 		sendErrorResponse("unable to generate fee address", http.StatusInternalServerError, c)

webapi/payfee.go

@@ -10,10 +10,10 @@ import (
 	"github.com/decred/dcrd/chaincfg/chainhash"
 	"github.com/decred/dcrd/dcrec"
 	"github.com/decred/dcrd/dcrutil/v3"
-	dcrdtypes "github.com/decred/dcrd/rpc/jsonrpc/types/v2"
 	"github.com/decred/dcrd/txscript/v3"
 	"github.com/decred/dcrd/wire"
 	"github.com/gin-gonic/gin"
+	"github.com/jholdstock/dcrvsp/rpc"
 )
 
 // payFee is the handler for "POST /payfee"
@@ -131,31 +131,49 @@ findAddress:
 		return
 	}
 
-	walletClient, err := walletRPC()
+	fWalletConn, err := feeWalletConnect()
 	if err != nil {
-		log.Errorf("Failed to dial dcrwallet RPC: %v", err)
+		log.Errorf("Fee wallet connection error: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
-
 	ctx := c.Request.Context()
-	var rawTicket dcrdtypes.TxRawResult
 
-	err = walletClient.Call(ctx, "getrawtransaction", &rawTicket, ticketHash.String(), 1)
+	fWalletClient, err := rpc.FeeWalletClient(ctx, fWalletConn)
 	if err != nil {
-		log.Errorf("GetRawTransaction failed: %v", err)
+		log.Errorf("Fee wallet client error: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
 
-	err = walletClient.Call(ctx, "addtransaction", nil, rawTicket.BlockHash, rawTicket.Hex)
+	rawTicket, err := fWalletClient.GetRawTransaction(ctx, ticketHash.String())
+	if err != nil {
+		log.Warnf("Could not retrieve tx %s for %s: %v", ticketHash.String(), c.ClientIP(), err)
+		sendErrorResponse("unknown transaction", http.StatusBadRequest, c)
+		return
+	}
+
+	vWalletConn, err := votingWalletConnect()
+	if err != nil {
+		log.Errorf("Voting wallet connection error: %v", err)
+		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
+		return
+	}
+	vWalletClient, err := rpc.VotingWalletClient(ctx, vWalletConn)
+	if err != nil {
+		log.Errorf("Voting wallet client error: %v", err)
+		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
+		return
+	}
+
+	err = vWalletClient.AddTransaction(ctx, rawTicket.BlockHash, rawTicket.Hex)
 	if err != nil {
 		log.Errorf("AddTransaction failed: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
 
-	err = walletClient.Call(ctx, "importprivkey", nil, votingWIF.String(), "imported", false, 0)
+	err = vWalletClient.ImportPrivKey(ctx, votingWIF.String())
 	if err != nil {
 		log.Errorf("ImportPrivKey failed: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
@@ -164,9 +182,9 @@ findAddress:
 
 	// Update vote choices on voting wallets.
 	for agenda, choice := range voteChoices {
-		err = walletClient.Call(ctx, "setvotechoice", nil, agenda, choice, ticket.Hash)
+		err = vWalletClient.SetVoteChoice(ctx, agenda, choice, ticket.Hash)
 		if err != nil {
-			log.Errorf("setvotechoice failed: %v", err)
+			log.Errorf("SetVoteChoice failed: %v", err)
 			sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 			return
 		}
@@ -181,8 +199,7 @@ findAddress:
 		return
 	}
 
-	var sendTxHash string
+	sendTxHash, err := fWalletClient.SendRawTransaction(ctx, hex.EncodeToString(feeTxBuf.Bytes()))
-	err = walletClient.Call(ctx, "sendrawtransaction", &sendTxHash, hex.EncodeToString(feeTxBuf.Bytes()), false)
 	if err != nil {
 		log.Errorf("SendRawTransaction failed: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)

webapi/setvotechoices.go

@@ -9,6 +9,7 @@ import (
 	"github.com/decred/dcrd/chaincfg/chainhash"
 	"github.com/decred/dcrd/dcrutil/v3"
 	"github.com/gin-gonic/gin"
+	"github.com/jholdstock/dcrvsp/rpc"
 )
 
 // setVoteChoices is the handler for "POST /setvotechoices"
@@ -61,25 +62,33 @@ func setVoteChoices(c *gin.Context) {
 		return
 	}
 
-	walletClient, err := walletRPC()
+	vWalletConn, err := votingWalletConnect()
 	if err != nil {
-		log.Errorf("Failed to dial dcrwallet RPC: %v", err)
+		log.Errorf("Voting wallet connection error: %v", err)
 		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 		return
 	}
 
 	ctx := c.Request.Context()
+	vWalletClient, err := rpc.VotingWalletClient(ctx, vWalletConn)
+	if err != nil {
+		log.Errorf("Voting wallet client error: %v", err)
+		sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
+		return
+	}
 
 	// Update vote choices on voting wallets.
 	for agenda, choice := range voteChoices {
-		err = walletClient.Call(ctx, "setvotechoice", nil, agenda, choice, ticket.Hash)
+		err = vWalletClient.SetVoteChoice(ctx, agenda, choice, ticket.Hash)
 		if err != nil {
-			log.Errorf("setvotechoice failed: %v", err)
+			log.Errorf("SetVoteChoice failed: %v", err)
 			sendErrorResponse("dcrwallet RPC error", http.StatusInternalServerError, c)
 			return
 		}
 	}
 
+	// TODO: Update database before updating wallets. DB is source of truth and
+	// is less likely to error.
 	err = db.UpdateVoteChoices(txHash.String(), voteChoices)
 	if err != nil {
 		log.Errorf("UpdateVoteChoices error: %v", err)

webapi/webapi.go

@@ -28,10 +28,11 @@ type Config struct {
 
 var cfg Config
 var db *database.VspDatabase
-var walletRPC rpc.Client
+var feeWalletConnect rpc.Connect
+var votingWalletConnect rpc.Connect
 
 func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *sync.WaitGroup,
-	listen string, vdb *database.VspDatabase, wRPC rpc.Client, debugMode bool, config Config) error {
+	listen string, vdb *database.VspDatabase, fWalletConnect rpc.Connect, vWalletConnect rpc.Connect, debugMode bool, config Config) error {
 
 	// Create TCP listener.
 	var listenConfig net.ListenConfig
@@ -79,7 +80,8 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 
 	cfg = config
 	db = vdb
-	walletRPC = wRPC
+	feeWalletConnect = fWalletConnect
+	votingWalletConnect = vWalletConnect
 
 	return nil
 }