return more descriptive error messages on ticket auth failure

controllers/main.go

@@ -287,6 +287,10 @@ func (controller *MainController) API(c web.C, r *http.Request) *system.APIRespo
 		}
 	}
 
+	if invalidAuthMessage := c.Env["InvalidTicketAuthMessage"]; invalidAuthMessage != "" && code == codes.Unauthenticated {
+		err = fmt.Errorf("error processing ticket auth data: %s", invalidAuthMessage)
+	}
+
 	if err != nil {
 		status = "error"
 		response = response + " - " + err.Error()

v3api/middleware.go

@@ -13,8 +13,11 @@ func (v3Api *V3API) ApplyTicketAuth(c *web.C, h http.Handler) http.Handler {
 	fn := func(w http.ResponseWriter, r *http.Request) {
 		if strings.HasPrefix(r.URL.Path, "/api/v3") {
 			authHeader := r.Header.Get("Authorization")
-			msa := v3Api.validateTicketOwnership(authHeader)
-			if msa != "" {
+			msa, invalidAuthResponse := v3Api.validateTicketOwnership(authHeader)
+			if invalidAuthResponse != "" {
+				log.Warnf(invalidAuthResponse)
+				c.Env["InvalidTicketAuthMessage"] = invalidAuthResponse
+			} else if msa != "" {
 				dbMap := c.Env["DbMap"].(*gorp.DbMap)
 
 				user, err := models.GetUserByMSA(dbMap, msa)

v3api/ticketauth.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/decred/dcrd/dcrutil"
 	"github.com/decred/dcrwallet/wallet"
+	"fmt"
 )
 
 const (
@@ -19,41 +20,41 @@ const (
 	MaxTicketChallengeAge = 60 * 30 // 30 minutes
 )
 
-func (v3Api *V3API) validateTicketOwnership(authHeader string) (multiSigAddress string) {
+func (v3Api *V3API) validateTicketOwnership(authHeader string) (multiSigAddress, authValidationFailureReason string) {
 	if !strings.HasPrefix(authHeader, customAuthScheme) {
-		log.Warnf("invalid API v3 auth header value %s", authHeader)
+		authValidationFailureReason = fmt.Sprintf("invalid API v3 auth header value %s", authHeader)
 		return
 	}
 
 	timestamp, timestampSignature, ticketHash := extractAuthParams(strings.TrimPrefix(authHeader, customAuthScheme))
 	if timestamp == "" || timestampSignature == "" || ticketHash == "" {
-		log.Warnf("invalid API v3 auth header value %s", authHeader)
+		authValidationFailureReason = fmt.Sprintf("invalid API v3 auth header value %s", authHeader)
 		return
 	}
 
 	// Ensure that this signature had not been used in a previous authentication attempt.
 	if v3Api.processedTicketChallenges.containsChallenge(timestampSignature) {
-		log.Warnf("disallowed reuse of ticket auth signature %v", timestampSignature)
+		authValidationFailureReason = fmt.Sprintf("disallowed reuse of ticket auth signature %v", timestampSignature)
 		return
 	}
 
 	authTimestamp, err := strconv.Atoi(timestamp)
 	if err != nil {
-		log.Warnf("invalid ticket auth timestamp value %v", timestamp)
+		authValidationFailureReason = fmt.Sprintf("invalid ticket auth timestamp value %v", timestamp)
 		return
 	}
 
 	// Ensure that the auth timestamp is not in the future and is not more than 30 seconds into the past.
 	timestampDelta := time.Now().Unix() - int64(authTimestamp)
 	if timestampDelta < 0 || timestampDelta > v3Api.ticketChallengeMaxAge {
-		log.Warnf("expired ticket auth timestamp value %v", timestamp)
+		authValidationFailureReason = fmt.Sprintf("expired ticket auth timestamp value %v", timestamp)
 		return
 	}
 
 	// confirm that the timestamp signature is a valid base64 string
 	decodedSignature, err := base64.StdEncoding.DecodeString(timestampSignature)
 	if err != nil {
-		log.Warnf("invalid ticket auth signature %s", timestampSignature)
+		authValidationFailureReason = fmt.Sprintf("invalid ticket auth signature %s", timestampSignature)
 		return
 	}
 
@@ -67,20 +68,20 @@ func (v3Api *V3API) validateTicketOwnership(authHeader string) (multiSigAddress
 	// todo: may be better to maintain a memory map of tickets-userWalletAddresses
 	ticketInfo, err := v3Api.stakepooldConnMan.GetTicketInfo(ticketHash)
 	if err != nil {
-		log.Warnf("ticket auth, get ticket info failed: %v", err)
+		authValidationFailureReason = fmt.Sprintf("ticket auth, get ticket info failed: %v", err)
 		return
 	}
 
 	// check if timestamp signature checks out against address
 	addr, err := dcrutil.DecodeAddress(ticketInfo.OwnerFeeAddress)
 	if err != nil {
-		log.Errorf("ticket auth, unexpected decode address error: %v", err)
+		authValidationFailureReason = fmt.Sprintf("ticket auth, unexpected decode address error: %v", err)
 		return
 	}
 
 	valid, err := wallet.VerifyMessage(timestamp, addr, decodedSignature)
 	if err != nil {
-		log.Errorf("error validating timestamp signature for ticket auth %v", err)
+		authValidationFailureReason = fmt.Sprintf("error validating timestamp signature for ticket auth %v", err)
 		return
 	}