race the tcp connections (#6898)

Signed-off-by: abhishek818 <[email protected]>

Author: abhishek818

services/auth/source/ldap/source_search.go

@@ -112,50 +112,68 @@ func (source *Source) findUserDN(l *ldap.Conn, name string) (string, bool) {
 func dial(source *Source) (*ldap.Conn, error) {
 	log.Trace("Dialing LDAP with security protocol (%v) without verifying: %v", source.SecurityProtocol, source.SkipVerify)
 
-	ldap.DefaultTimeout = time.Second * 15
+	ldap.DefaultTimeout = time.Second * 10
 	// Remove any extra spaces in HostList string
 	tempHostList := strings.ReplaceAll(source.HostList, " ", "")
 	// HostList is a list of hosts separated by commas
 	hostList := strings.Split(tempHostList, ",")
-	// hostList := strings.Split(source.HostList, ",")
 
-	for _, host := range hostList {
-		tlsConfig := &tls.Config{
-			ServerName:         host,
-			InsecureSkipVerify: source.SkipVerify,
-		}
+	type result struct {
+		conn *ldap.Conn
+		err  error
+	}
 
-		if source.SecurityProtocol == SecurityProtocolLDAPS {
-			conn, err := ldap.DialTLS("tcp", net.JoinHostPort(host, strconv.Itoa(source.Port)), tlsConfig)
-			if err != nil {
-				// Connection failed, try again with the next host.
-				conn.Close()
-				log.Trace("error during Dial for host %s: %w", host, err)
-				continue
+	results := make(chan result, len(hostList))
+
+	for _, host := range hostList {
+		go func(host string) {
+			tlsConfig := &tls.Config{
+				ServerName:         host,
+				InsecureSkipVerify: source.SkipVerify,
 			}
-			conn.SetTimeout(time.Second * 10)
 
-			return conn, err
-		}
+			var conn *ldap.Conn
+			var err error
 
-		conn, err := ldap.Dial("tcp", net.JoinHostPort(host, strconv.Itoa(source.Port)))
-		if err != nil {
-			conn.Close()
-			log.Trace("error during Dial for host %s: %w", host, err)
-			continue
-		}
-		conn.SetTimeout(time.Second * 10)
+			if source.SecurityProtocol == SecurityProtocolLDAPS {
+				conn, err = ldap.DialTLS("tcp", net.JoinHostPort(host, strconv.Itoa(source.Port)), tlsConfig)
+			} else {
+				conn, err = ldap.Dial("tcp", net.JoinHostPort(host, strconv.Itoa(source.Port)))
+				if err == nil && source.SecurityProtocol == SecurityProtocolStartTLS {
+					err = conn.StartTLS(tlsConfig)
+				}
+			}
 
-		if source.SecurityProtocol == SecurityProtocolStartTLS {
-			if err = conn.StartTLS(tlsConfig); err != nil {
-				conn.Close()
-				log.Trace("error during StartTLS for host %s: %w", host, err)
-				continue
+			if err != nil {
+				if conn != nil {
+					conn.Close()
+				}
+				log.Trace("error during Dial for host %s: %w", host, err)
+				results <- result{nil, err}
+				return
 			}
+
+			conn.SetTimeout(time.Second * 10)
+			results <- result{conn, nil}
+		}(host)
+	}
+
+	for range hostList {
+		r := <-results
+		if r.err == nil {
+			// Close other connections still in progress
+			go func() {
+				for range hostList {
+					r := <-results
+					if r.conn != nil {
+						r.conn.Close()
+					}
+				}
+			}()
+			return r.conn, nil
 		}
 	}
 
-	// All servers were unreachable
 	return nil, fmt.Errorf("dial failed for all provided servers: %s", hostList)
 }