speed up email checks execution

vendor/gitlab.com/etke.cc/go/validator/emails.go

@@ -1,98 +1,142 @@
 package validator
 
 import (
+	"fmt"
 	"net"
 	"net/mail"
 	"strings"
+	"time"
 
 	"blitiri.com.ar/go/spf"
 	"gitlab.com/etke.cc/go/trysmtp"
+	"golang.org/x/net/context"
 )
 
 // Email checks if email is valid
 func (v *V) Email(email string, optionalSenderIP ...net.IP) bool {
-	var senderIP net.IP
-	if len(optionalSenderIP) > 0 {
-		senderIP = optionalSenderIP[0]
-	}
 
 	// edge case: email may be optional
 	if email == "" {
 		return !v.enforce.Email
 	}
 
-	length := len(email)
-	// email cannot too short and too big
-	if length < 3 || length > 254 {
-		v.log.Info("email %s invalid, reason: length", email)
-		return false
-	}
-
-	_, err := mail.ParseAddress(email)
+	address, err := mail.ParseAddress(email)
 	if err != nil {
 		v.log.Info("email %s invalid, reason: %v", email, err)
 		return false
 	}
-
-	emailb := []byte(email)
-	for _, spamregex := range v.spamlist {
-		if spamregex.Match(emailb) {
-			v.log.Info("email %s invalid, reason: spamlist", email)
-			return false
-		}
-	}
-
-	if v.enforce.MX {
-		if v.emailNoMX(email) {
-			return false
-		}
-	}
-
-	if v.enforce.SPF {
-		if v.emailNoSPF(email, senderIP) {
-			return false
-		}
-	}
-
-	if v.enforce.SMTP {
-		if v.emailNoSMTP(email) {
-			return false
-		}
-	}
-
-	return true
+	email = address.Address
+	return v.emailChecks(email, optionalSenderIP...)
 }
 
-func (v *V) emailNoMX(email string) bool {
-	at := strings.LastIndex(email, "@")
-	domain := email[at+1:]
-
-	nomx := !v.MX(domain)
-	if nomx {
-		v.log.Info("email %s domain %s invalid, reason: no MX", email, domain)
-		return true
+func (v *V) emailChecks(email string, optionalSenderIP ...net.IP) bool {
+	maxChecks := 4
+	var senderIP net.IP
+	if len(optionalSenderIP) > 0 {
+		senderIP = optionalSenderIP[0]
 	}
+	errchan := make(chan error, maxChecks)
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
 
-	return false
-}
+	go v.emailSpamlist(ctx, email, errchan)
+	go v.emailNoMX(ctx, email, errchan)
+	go v.emailNoSPF(ctx, email, senderIP, errchan)
+	go v.emailNoSMTP(ctx, email, errchan)
 
-func (v *V) emailNoSMTP(email string) bool {
-	client, err := trysmtp.Connect(v.from, email)
-	if err != nil {
-		if strings.HasPrefix(err.Error(), "45") {
-			v.log.Info("email %s may be invalid, reason: SMTP check (%v)", email, err)
+	var checks int
+	for {
+		checks++
+		err := <-errchan
+		if err != nil {
+			v.log.Info("email %q is invalid, reason: %v", email, err)
 			return false
 		}
-
-		v.log.Info("email %s invalid, reason: SMTP check (%v)", email, err)
-		return true
+		if checks >= maxChecks {
+			return true
+		}
 	}
-	defer client.Close()
-
-	return false
 }
 
-func (v *V) emailNoSPF(email string, senderIP net.IP) bool {
-	result, _ := spf.CheckHostWithSender(senderIP, "", email, spf.WithTraceFunc(v.log.Info)) //nolint:errcheck // not a error
-	return result == spf.Fail
+func (v *V) emailSpamlist(ctx context.Context, email string, errchan chan error) {
+	select {
+	case <-ctx.Done():
+		return
+	default:
+		emailb := []byte(email)
+		for _, spamregex := range v.spamlist {
+			if spamregex.Match(emailb) {
+				errchan <- fmt.Errorf("spamlist")
+				return
+			}
+		}
+		errchan <- nil
+	}
+}
+
+func (v *V) emailNoMX(ctx context.Context, email string, errchan chan error) {
+	select {
+	case <-ctx.Done():
+		return
+	default:
+		if !v.enforce.MX {
+			errchan <- nil
+			return
+		}
+
+		at := strings.LastIndex(email, "@")
+		domain := email[at+1:]
+		if !v.MX(domain) {
+			v.log.Info("email %s domain %s invalid, reason: no MX", email, domain)
+			errchan <- fmt.Errorf("no MX")
+			return
+		}
+		errchan <- nil
+	}
+}
+
+func (v *V) emailNoSMTP(ctx context.Context, email string, errchan chan error) {
+	select {
+	case <-ctx.Done():
+		return
+	default:
+		if !v.enforce.SMTP {
+			errchan <- nil
+			return
+		}
+
+		client, err := trysmtp.Connect(v.from, email)
+		if err != nil {
+			if strings.HasPrefix(err.Error(), "45") {
+				v.log.Info("email %s may be invalid, reason: SMTP check (%v)", email, err)
+				errchan <- nil
+				return
+			}
+
+			v.log.Info("email %s invalid, reason: SMTP check (%v)", email, err)
+			errchan <- fmt.Errorf("SMTP")
+			return
+		}
+		client.Close()
+		errchan <- nil
+	}
+}
+
+func (v *V) emailNoSPF(ctx context.Context, email string, senderIP net.IP, errchan chan error) {
+	select {
+	case <-ctx.Done():
+		return
+	default:
+		if !v.enforce.SPF {
+			errchan <- nil
+			return
+		}
+
+		result, _ := spf.CheckHostWithSender(senderIP, "", email, spf.WithTraceFunc(v.log.Info)) //nolint:errcheck // not a error
+		if result == spf.Fail {
+			errchan <- fmt.Errorf("SPF")
+			return
+		}
+		errchan <- nil
+	}
 }