multi: add pre-paid bonds (#2730)

* add prepaid bonds

client/core/bond.go

@@ -15,6 +15,7 @@ import (
 	"decred.org/dcrdex/dex"
 	"decred.org/dcrdex/dex/keygen"
 	"decred.org/dcrdex/dex/msgjson"
+	"decred.org/dcrdex/server/account"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/decred/dcrd/hdkeychain/v3"
 )
@@ -807,20 +808,21 @@ func (c *Core) postBond(dc *dexConnection, bond *asset.Bond) (*msgjson.PostBondR
 		return nil, codedError(registerErr, err)
 	}
 
-	dc.acct.authMtx.Lock()
-	dc.updateReputation(postBondRes.Reputation, postBondRes.Tier, nil, nil)
-	dc.acct.authMtx.Unlock()
-
 	// Check the response signature.
 	err = dc.acct.checkSig(postBondRes.Serialize(), postBondRes.Sig)
 	if err != nil {
 		c.log.Warnf("postbond: DEX signature validation error: %v", err)
 	}
+
 	if !bytes.Equal(postBondRes.BondID, bondCoin) {
 		return nil, fmt.Errorf("server reported bond coin ID %v, expected %v", coinIDString(assetID, postBondRes.BondID),
 			bondCoinStr)
 	}
 
+	dc.acct.authMtx.Lock()
+	dc.updateReputation(postBondRes.Reputation, postBondRes.Tier, nil, nil)
+	dc.acct.authMtx.Unlock()
+
 	return postBondRes, nil
 }
 
@@ -926,6 +928,136 @@ func (c *Core) monitorBondConfs(dc *dexConnection, bond *asset.Bond, reqConfs ui
 	})
 }
 
+// RedeemPrepaidBond redeems a pre-paid bond for a dcrdex host server.
+func (c *Core) RedeemPrepaidBond(appPW []byte, code []byte, host string, certI any) (tier uint64, err error) {
+	// Make sure the app has been initialized.
+	if !c.IsInitialized() {
+		return 0, fmt.Errorf("app not initialized")
+	}
+
+	// Check the app password.
+	crypter, err := c.encryptionKey(appPW)
+	if err != nil {
+		return 0, codedError(passwordErr, err)
+	}
+	defer crypter.Close()
+
+	var success, acctExists bool
+
+	c.connMtx.RLock()
+	dc, found := c.conns[host]
+	c.connMtx.RUnlock()
+	if found {
+		acctExists = !dc.acct.isViewOnly()
+		if acctExists {
+			if dc.acct.locked() { // require authDEX first to reconcile any existing bond statuses
+				return 0, newError(acctKeyErr, "acct locked %s (login first)", host)
+			}
+		}
+	} else {
+		// New DEX connection.
+		cert, err := parseCert(host, certI, c.net)
+		if err != nil {
+			return 0, newError(fileReadErr, "failed to read certificate file from %s: %v", cert, err)
+		}
+		dc, err = c.connectDEX(&db.AccountInfo{
+			Host: host,
+			Cert: cert,
+			// bond maintenance options set below.
+		})
+		if err != nil {
+			return 0, codedError(connectionErr, err)
+		}
+
+		// Close the connection to the dex server if the registration fails.
+		defer func() {
+			if !success {
+				dc.connMaster.Disconnect()
+			}
+		}()
+	}
+
+	if !acctExists { // new dex connection or pre-existing view-only connection
+		_, err := c.discoverAccount(dc, crypter)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	pkBytes := dc.acct.pubKey()
+	if len(pkBytes) == 0 {
+		return 0, fmt.Errorf("account keys not decrypted")
+	}
+
+	// Do a postbond request with the raw bytes of the unsigned tx, the bond
+	// script, and our account pubkey.
+	postBond := &msgjson.PostBond{
+		AcctPubKey: pkBytes,
+		AssetID:    account.PrepaidBondID,
+		// Version:    0,
+		CoinID: code,
+	}
+	postBondRes := new(msgjson.PostBondResult)
+	if err = dc.signAndRequest(postBond, msgjson.PostBondRoute, postBondRes, DefaultResponseTimeout); err != nil {
+		return 0, codedError(registerErr, err)
+	}
+
+	// Check the response signature.
+	err = dc.acct.checkSig(postBondRes.Serialize(), postBondRes.Sig)
+	if err != nil {
+		c.log.Warnf("postbond: DEX signature validation error: %v", err)
+	}
+
+	lockTime := postBondRes.Expiry + dc.config().BondExpiry
+
+	dbBond := &db.Bond{
+		// Version:    0,
+		AssetID:   account.PrepaidBondID,
+		CoinID:    code,
+		LockTime:  lockTime,
+		Strength:  postBondRes.Strength,
+		Confirmed: true,
+	}
+
+	dc.acct.authMtx.Lock()
+	dc.updateReputation(postBondRes.Reputation, postBondRes.Tier, nil, nil)
+	dc.acct.bonds = append(dc.acct.bonds, dbBond)
+	dc.acct.authMtx.Unlock()
+
+	if !acctExists {
+		dc.acct.keyMtx.RLock()
+		ai := &db.AccountInfo{
+			Host:      dc.acct.host,
+			Cert:      dc.acct.cert,
+			DEXPubKey: dc.acct.dexPubKey,
+			EncKeyV2:  dc.acct.encKey,
+			Bonds:     []*db.Bond{dbBond},
+		}
+		dc.acct.keyMtx.RUnlock()
+
+		if err = c.dbCreateOrUpdateAccount(dc, ai); err != nil {
+			return 0, fmt.Errorf("failed to store pre-paid account for dex %s: %w", host, err)
+		}
+		c.addDexConnection(dc)
+	}
+
+	success = true // Don't disconnect anymore.
+
+	if err = c.db.AddBond(dc.acct.host, dbBond); err != nil {
+		return 0, fmt.Errorf("failed to store pre-paid bond for dex %s: %w", host, err)
+	}
+
+	if err = c.bondConfirmed(dc, account.PrepaidBondID, code, postBondRes); err != nil {
+		return 0, fmt.Errorf("bond redeemed, but failed to auth: %v", err)
+	}
+
+	c.updateBondReserves()
+
+	c.notify(newBondAuthUpdate(dc.acct.host, c.exchangeAuth(dc)))
+
+	return uint64(postBondRes.Strength), nil
+}
+
 func deriveBondKey(bondXPriv *hdkeychain.ExtendedKey, assetID, bondIndex uint32) (*secp256k1.PrivateKey, error) {
 	kids := []uint32{
 		assetID + hdkeychain.HardenedKeyStart,

client/core/core.go

@@ -4033,7 +4033,7 @@ func (c *Core) GetDEXConfig(dexAddr string, certI any) (*Exchange, error) {
 // activity without setting up account keys or communicating account identity
 // with the DEX. DiscoverAccount, Post Bond or Register (deprecated) may be used
 // to set up a trading account for this DEX if required.
-func (c *Core) AddDEX(dexAddr string, certI any) error {
+func (c *Core) AddDEX(appPW []byte, dexAddr string, certI any) error {
 	if !c.IsInitialized() { // TODO: Allow adding view-only DEX without init.
 		return fmt.Errorf("cannot register DEX because app has not been initialized")
 	}
@@ -4097,6 +4097,23 @@ func (c *Core) AddDEX(dexAddr string, certI any) error {
 	c.conns[dc.acct.host] = dc
 	c.connMtx.Unlock()
 
+	// If a password was provided, try discoverAccount, but OK if we don't find
+	// it.
+	if len(appPW) > 0 {
+		crypter, err := c.encryptionKey(appPW)
+		if err != nil {
+			return codedError(passwordErr, err)
+		}
+		defer crypter.Close()
+
+		paid, err := c.discoverAccount(dc, crypter)
+		if err != nil {
+			c.log.Errorf("discoverAccount error during AddDEX: %v", err)
+		} else if paid {
+			c.upgradeConnection(dc)
+		}
+	}
+
 	return nil
 }
 
@@ -7075,6 +7092,10 @@ func (c *Core) findBondKeyIdx(pkhEqualFn func(bondKey *secp256k1.PrivateKey) boo
 // findBond will attempt to find an unknown bond and add it to the live bonds
 // slice and db for refunding later. Returns the bond strength if no error.
 func (c *Core) findBond(dc *dexConnection, bond *msgjson.Bond) (strength, bondAssetID uint32) {
+	if bond.AssetID == account.PrepaidBondID {
+		c.insertPrepaidBond(dc, bond)
+		return bond.Strength, bond.AssetID
+	}
 	symb := dex.BipIDSymbol(bond.AssetID)
 	bondIDStr := coinIDString(bond.AssetID, bond.CoinID)
 	c.log.Warnf("Unknown bond reported by server: %v (%s)", bondIDStr, symb)
@@ -7140,6 +7161,27 @@ func (c *Core) findBond(dc *dexConnection, bond *msgjson.Bond) (strength, bondAs
 	return strength, bondDetails.AssetID
 }
 
+func (c *Core) insertPrepaidBond(dc *dexConnection, bond *msgjson.Bond) {
+	lockTime := bond.Expiry + dc.config().BondExpiry
+	dbBond := &db.Bond{
+		Version:   bond.Version,
+		AssetID:   bond.AssetID,
+		CoinID:    bond.CoinID,
+		LockTime:  lockTime,
+		Strength:  bond.Strength,
+		Confirmed: true,
+	}
+
+	err := c.db.AddBond(dc.acct.host, dbBond)
+	if err != nil {
+		c.log.Errorf("Failed to store pre-paid bond dex %v: %w", dc.acct.host, err)
+	}
+
+	dc.acct.authMtx.Lock()
+	dc.acct.bonds = append(dc.acct.bonds, dbBond)
+	dc.acct.authMtx.Unlock()
+}
+
 func (dc *dexConnection) maxScore() uint32 {
 	if maxScore := dc.config().MaxScore; maxScore > 0 {
 		return maxScore

client/core/types.go

@@ -1116,6 +1116,9 @@ func token(id []byte) string {
 // coinIDString converts a coin ID to a human-readable string. If an error is
 // encountered the value starting with "<invalid coin>:" prefix is returned.
 func coinIDString(assetID uint32, coinID []byte) string {
+	if assetID == account.PrepaidBondID {
+		return "prepaid-bond:" + hex.EncodeToString(coinID)
+	}
 	coinStr, err := asset.DecodeCoinID(assetID, coinID)
 	if err != nil {
 		// Logging error here with fmt.Printf is better than dropping it. It's not

client/webserver/api.go

@@ -28,9 +28,15 @@ func (s *WebServer) apiAddDEX(w http.ResponseWriter, r *http.Request) {
 	if !readPost(w, r, form) {
 		return
 	}
-	cert := []byte(form.Cert)
-	err := s.core.AddDEX(form.Addr, cert)
+	defer form.AppPW.Clear()
+	appPW, err := s.resolvePass(form.AppPW, r)
 	if err != nil {
+		s.writeAPIError(w, fmt.Errorf("password error: %w", err))
+		return
+	}
+	cert := []byte(form.Cert)
+
+	if err = s.core.AddDEX(appPW, form.Addr, cert); err != nil {
 		s.writeAPIError(w, err)
 		return
 	}
@@ -469,6 +475,37 @@ func (s *WebServer) apiUpdateBondOptions(w http.ResponseWriter, r *http.Request)
 	writeJSON(w, simpleAck(), s.indent)
 }
 
+func (s *WebServer) apiRedeemPrepaidBond(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		Host  string           `json:"host"`
+		Code  dex.Bytes        `json:"code"`
+		AppPW encode.PassBytes `json:"appPW"`
+		Cert  string           `json:"cert"`
+	}
+	defer req.AppPW.Clear()
+	if !readPost(w, r, &req) {
+		return
+	}
+	appPW, err := s.resolvePass(req.AppPW, r)
+	if err != nil {
+		s.writeAPIError(w, fmt.Errorf("password error: %w", err))
+		return
+	}
+	tier, err := s.core.RedeemPrepaidBond(appPW, req.Code, req.Host, req.Cert)
+	if err != nil {
+		s.writeAPIError(w, err)
+		return
+	}
+	resp := &struct {
+		OK   bool   `json:"ok"`
+		Tier uint64 `json:"tier"`
+	}{
+		OK:   true,
+		Tier: tier,
+	}
+	writeJSON(w, resp, s.indent)
+}
+
 // apiNewWallet is the handler for the '/newwallet' API request.
 func (s *WebServer) apiNewWallet(w http.ResponseWriter, r *http.Request) {
 	form := new(newWalletForm)

client/webserver/live_test.go

@@ -638,7 +638,7 @@ func (c *TCore) GetDEXConfig(host string, certI any) (*core.Exchange, error) {
 	return tExchanges[firstDEX], nil
 }
 
-func (c *TCore) AddDEX(dexAddr string, certI any) error {
+func (c *TCore) AddDEX(appPW []byte, dexAddr string, certI any) error {
 	randomDelay()
 	if initErrors {
 		return fmt.Errorf("forced init error")
@@ -681,6 +681,9 @@ func (c *TCore) PostBond(form *core.PostBondForm) (*core.PostBondResult, error)
 		ReqConfirms: uint16(ba.Confs),
 	}, nil
 }
+func (c *TCore) RedeemPrepaidBond(appPW []byte, code []byte, host string, certI any) (tier uint64, err error) {
+	return 1, nil
+}
 func (c *TCore) UpdateBondOptions(form *core.BondOptionsForm) error {
 	xc := tExchanges[form.Host]
 	xc.ViewOnly = false

client/webserver/site/src/html/bodybuilder.tmpl

@@ -13,7 +13,7 @@
 </head>
 <body >
   <div class="popup-notes d-hide" id="popupNotes">
-    <span data-tmpl="note fs15">
+    <span data-tmpl="note" class="fs15">
       <div class="note-indicator d-inline-block" data-tmpl="indicator"></div>
       <span data-tmpl="text"></span>
     </span>

client/webserver/site/src/html/forms.tmpl

@@ -263,7 +263,7 @@
 <div data-tmpl="assetForm">
   <h3 class="text-center">[[[Select your bond asset]]]</h3>
   <div data-tmpl="regAssetErr" class="fs14 text-danger flex-center"></div>
-  <div data-tmpl="bondAssets" class="mt-2">
+  <div data-tmpl="bondAssets">
 
     <div data-tmpl="bondAssetTmpl" class="border rounded3 d-flex align-items-stretch p-2 hoverbg pointer mt-3">
       <div class="flex-center pe-4">
@@ -287,6 +287,10 @@
     </div>
 
   </div>
+  <button type="button" data-tmpl="usePrepaidBond" class="w-100 mt-3">
+    <span class="ico-ticket fs22 me-2"></span>
+    <span class="fs22">Use a pre-paid bond</span>
+  </button>
   <div data-tmpl="whatsABond" class="flex-center fs18 hoverbg pointer underline pt-2 pb-1 mt-1">[[[what_s_a_bond]]]</div>
 </div>
 
@@ -431,6 +435,22 @@
     </tbody>
   </table>
 </div>
+<div data-tmpl="prepaidBonds" class="d-hide">
+  <div class="py-2 fs14 grey">
+    <span class="hoverbg pointer" data-tmpl="ppbGoBack"><span class="ico-arrowback fs12 me-1"></span> go back</span>
+  </div>
+  <h3>Redeem Pre-paid Bond</h3>
+  <label for="prepaidBondCode">Code</label>
+  <input type="text" data-tmpl="prepaidBondCode" autocomplete="off">
+  <div data-tmpl="prepaidBondPWBox">
+    <label for="ppbAppPW">[[[Password]]]</label>
+    <input type="password" data-tmpl="prepaidBondPW" autocomplete="off">
+  </div>
+  <div data-tmpl="prepaidBondErr" class="pt-2 px-2 text-danger d-hide"></div>
+  <div class="text-left mt-2">
+    <button data-tmpl="submitPrepaidBond" type="button" class="go">[[[Submit]]]</button>
+  </div>
+</div>
 {{end}}
 
 {{define "loginForm"}}

client/webserver/site/src/html/register.tmpl

@@ -42,7 +42,6 @@
     <form class="d-hide" id="walletWait">
       {{template "waitingForWalletForm"}}
     </form>
-
   </div>
 </div>
 {{template "bottom"}}