cli: implement round-robin DNS IP rotation This change introduces det…

cli/client.go

@@ -51,13 +51,21 @@ const (
 	hostSelectTypeWeighed    hostSelectType = "weighed"
 )
 
+// hostPair holds a resolved host and the original hostname it was resolved from.
+// originalHost is "" when --resolve-host is not used (no pinning needed).
+type hostPair struct {
+	resolved     string // IP:port to dial
+	originalHost string // original hostname (for S3 signing + SNI)
+}
+
 func newClient(ctx *cli.Context) func() (cl *minio.Client, done func()) {
-	hosts := parseHosts(ctx.String("host"), ctx.Bool("resolve-host"))
-	switch len(hosts) {
+	pairs := parseHostPairs(ctx.String("host"), ctx.Bool("resolve-host"))
+
+	switch len(pairs) {
 	case 0:
 		fatalIf(probe.NewError(errors.New("no host defined")), "Unable to create MinIO client")
 	case 1:
-		cl, err := getClient(ctx, hosts[0])
+		cl, err := getClient(ctx, pairs[0].resolved, pairs[0].originalHost)
 		fatalIf(probe.NewError(err), "Unable to create MinIO client")
 
 		return func() (*minio.Client, func()) {
@@ -70,9 +78,9 @@ func newClient(ctx *cli.Context) func() (cl *minio.Client, done func()) {
 		// Do round-robin.
 		var current int
 		var mu sync.Mutex
-		clients := make([]*minio.Client, len(hosts))
-		for i := range hosts {
-			cl, err := getClient(ctx, hosts[i])
+		clients := make([]*minio.Client, len(pairs))
+		for i := range pairs {
+			cl, err := getClient(ctx, pairs[i].resolved, pairs[i].originalHost)
 			fatalIf(probe.NewError(err), "Unable to create MinIO client")
 			clients[i] = cl
 		}
@@ -87,20 +95,20 @@ func newClient(ctx *cli.Context) func() (cl *minio.Client, done func()) {
 		// Keep track of handed out clients.
 		// Select random between the clients that have the fewest handed out.
 		var mu sync.Mutex
-		clients := make([]*minio.Client, len(hosts))
-		for i := range hosts {
-			cl, err := getClient(ctx, hosts[i])
+		clients := make([]*minio.Client, len(pairs))
+		for i := range pairs {
+			cl, err := getClient(ctx, pairs[i].resolved, pairs[i].originalHost)
 			fatalIf(probe.NewError(err), "Unable to create MinIO client")
 			clients[i] = cl
 		}
-		running := make([]int, len(hosts))
-		lastFinished := make([]time.Time, len(hosts))
+		running := make([]int, len(pairs))
+		lastFinished := make([]time.Time, len(pairs))
 		{
 			// Start with a random host
 			now := time.Now()
-			off := rand.New(rand.NewSource(time.Now().UnixNano())).Intn(len(hosts))
+			off := rand.New(rand.NewSource(time.Now().UnixNano())).Intn(len(pairs))
 			for i := range lastFinished {
-				lastFinished[i] = now.Add(time.Duration(i + off%len(hosts)))
+				lastFinished[i] = now.Add(time.Duration(i + off%len(pairs)))
 			}
 		}
 		find := func() int {
@@ -159,13 +167,19 @@ func detectLocalIP(host string) string {
 }
 
 // getClient creates a client with the specified host and the options set in the context.
-func getClient(ctx *cli.Context, host string) (*minio.Client, error) {
+// host is the resolved IP:port to dial; originalHost is the logical hostname for S3 signing
+// and SNI (empty when --resolve-host is not used).
+func getClient(ctx *cli.Context, host, originalHost string) (*minio.Client, error) {
 	var creds *credentials.Credentials
 	localIP := clientListenIP
 	if localIP == "" {
 		localIP = detectLocalIP(host)
 	}
-	transport := clientTransportWithLocalIP(ctx, localIP)
+	endpoint := host
+	if originalHost != "" {
+		endpoint = originalHost
+	}
+	transport := clientTransportWithLocalIP(ctx, localIP, host, originalHost)
 	switch strings.ToUpper(ctx.String("signature")) {
 	case "S3V4":
 		// if Signature version '4' use NewV4 directly.
@@ -189,7 +203,7 @@ func getClient(ctx *cli.Context, host string) (*minio.Client, error) {
 		if ctx.Bool("tls") || ctx.Bool("ktls") {
 			proto = "https"
 		}
-		stsEndPoint := fmt.Sprintf("%s://%s", proto, host)
+		stsEndPoint := fmt.Sprintf("%s://%s", proto, endpoint)
 		creds, err = credentials.NewSTSWebIdentity(stsEndPoint, func() (*credentials.WebIdentityToken, error) {
 			stsToken := ctx.String("sts-web-token")
 			if stsTokenFile, hasFilePrefix := strings.CutPrefix(stsToken, "file:"); hasFilePrefix {
@@ -214,7 +228,7 @@ func getClient(ctx *cli.Context, host string) (*minio.Client, error) {
 	} else if ctx.String("lookup") == "path" {
 		lookup = minio.BucketLookupPath
 	}
-	cl, err := minio.New(host, &minio.Options{
+	cl, err := minio.New(endpoint, &minio.Options{
 		Creds:           creds,
 		Secure:          ctx.Bool("tls") || ctx.Bool("ktls"),
 		Region:          ctx.String("region"),
@@ -236,19 +250,21 @@ func getClient(ctx *cli.Context, host string) (*minio.Client, error) {
 }
 
 func clientTransport(ctx *cli.Context) http.RoundTripper {
-	return clientTransportWithLocalIP(ctx, "")
+	return clientTransportWithLocalIP(ctx, "", "", "")
 }
 
 // clientTransportWithLocalIP creates a transport that binds outbound connections
 // to localIP (empty string means no binding, OS picks the source address).
-func clientTransportWithLocalIP(ctx *cli.Context, localIP string) http.RoundTripper {
+// When resolvedHost and originalHost are both non-empty, the transport also rewrites
+// dial addresses from originalHost to resolvedHost and sets TLS SNI from originalHost.
+func clientTransportWithLocalIP(ctx *cli.Context, localIP, resolvedHost, originalHost string) http.RoundTripper {
 	switch {
 	case ctx.Bool("ktls"):
-		return clientTransportKTLS(ctx, localIP)
+		return clientTransportKTLS(ctx, localIP, resolvedHost, originalHost)
 	case ctx.Bool("tls"):
-		return clientTransportTLS(ctx, localIP)
+		return clientTransportTLS(ctx, localIP, resolvedHost, originalHost)
 	default:
-		return clientTransportDefault(ctx, localIP)
+		return clientTransportDefault(ctx, localIP, resolvedHost)
 	}
 }
 
@@ -325,6 +341,39 @@ func parseHosts(h string, resolveDNS bool) []string {
 	return resolved
 }
 
+// parseHostPairs parses the host string into hostPair slices. When resolveDNS is true,
+// each hostname is resolved to its IPs and each IP becomes a separate pair carrying the
+// original hostname so that S3 signing and SNI remain correct.
+func parseHostPairs(h string, resolveDNS bool) []hostPair {
+	raw := parseHosts(h, false)
+	if !resolveDNS {
+		pairs := make([]hostPair, len(raw))
+		for i, r := range raw {
+			pairs[i] = hostPair{resolved: r}
+		}
+		return pairs
+	}
+	var pairs []hostPair
+	for _, hostport := range raw {
+		host, port, _ := net.SplitHostPort(hostport)
+		if host == "" {
+			host = hostport
+		}
+		ips, err := net.LookupIP(host)
+		if err != nil {
+			fatalIf(probe.NewError(err), "Could not get IPs for "+hostport)
+		}
+		for _, ip := range ips {
+			resolved := ip.String()
+			if port != "" {
+				resolved = ip.String() + ":" + port
+			}
+			pairs = append(pairs, hostPair{resolved: resolved, originalHost: hostport})
+		}
+	}
+	return pairs
+}
+
 // mustGetSystemCertPool - return system CAs or empty pool in case of error (or windows)
 func mustGetSystemCertPool() *x509.CertPool {
 	rootCAs, err := certs.GetRootCAs("")
@@ -338,15 +387,19 @@ func mustGetSystemCertPool() *x509.CertPool {
 }
 
 func newAdminClient(ctx *cli.Context) *madmin.AdminClient {
-	hosts := parseHosts(ctx.String("host"), ctx.Bool("resolve-host"))
-	if len(hosts) == 0 {
+	pairs := parseHostPairs(ctx.String("host"), ctx.Bool("resolve-host"))
+	if len(pairs) == 0 {
 		fatalIf(probe.NewError(errors.New("no host defined")), "Unable to create MinIO admin client")
 	}
 
-	cl, err := madmin.NewWithOptions(hosts[0], &madmin.Options{
+	endpoint := pairs[0].resolved
+	if pairs[0].originalHost != "" {
+		endpoint = pairs[0].originalHost
+	}
+	cl, err := madmin.NewWithOptions(endpoint, &madmin.Options{
 		Creds:     credentials.NewStaticV4(ctx.String("access-key"), ctx.String("secret-key"), ""),
 		Secure:    ctx.Bool("tls") || ctx.Bool("ktls"),
-		Transport: clientTransport(ctx),
+		Transport: clientTransportWithLocalIP(ctx, "", pairs[0].resolved, pairs[0].originalHost),
 	})
 	fatalIf(probe.NewError(err), "Unable to create MinIO admin client")
 	cl.SetAppInfo(appName, pkg.Version)

cli/client_default.go

@@ -23,6 +23,10 @@ import (
 	"github.com/minio/cli"
 )
 
-func clientTransportDefault(ctx *cli.Context, localIP string) http.RoundTripper {
+func clientTransportDefault(ctx *cli.Context, localIP, resolvedHost string) http.RoundTripper {
+	dialer := makeDialer(localIP)
+	if resolvedHost != "" {
+		return newClientTransport(ctx, withResolveHost(resolvedHost, resolvedHost, dialer, false))
+	}
 	return newClientTransport(ctx, withLocalAddr(localIP))
 }

cli/client_ktls.go

@@ -18,6 +18,8 @@
 package cli
 
 import (
+	"context"
+	"net"
 	stdHttp "net/http"
 	"os"
 	"time"
@@ -27,7 +29,15 @@ import (
 	"gitlab.com/go-extension/tls"
 )
 
-func clientTransportKTLS(ctx *cli.Context, localIP string) stdHttp.RoundTripper {
+func clientTransportKTLS(ctx *cli.Context, localIP, resolvedHost, originalHost string) stdHttp.RoundTripper {
+	var sni string
+	if originalHost != "" {
+		if h, _, err := net.SplitHostPort(originalHost); err == nil {
+			sni = h
+		} else {
+			sni = originalHost
+		}
+	}
 	// Keep TLS config.
 	tlsConfig := &tls.Config{
 		RootCAs: mustGetSystemCertPool(),
@@ -36,6 +46,7 @@ func clientTransportKTLS(ctx *cli.Context, localIP string) stdHttp.RoundTripper
 		// Can't use TLSv1.1 because of RC4 cipher usage
 		MinVersion:         tls.VersionTLS12,
 		InsecureSkipVerify: ctx.Bool("insecure"),
+		ServerName:         sni,
 		ClientSessionCache: tls.NewLRUClientSessionCache(1024), // up to 1024 nodes
 
 		// Extra configs
@@ -54,16 +65,42 @@ func clientTransportKTLS(ctx *cli.Context, localIP string) stdHttp.RoundTripper
 
 	netD := makeDialer(localIP)
 
+	getDialAddr := func(addr string) string {
+		if originalHost == "" || resolvedHost == "" {
+			return addr
+		}
+		host, port, err := net.SplitHostPort(addr)
+		if err != nil {
+			host = addr
+			port = "443"
+		}
+		targetHost, _, err := net.SplitHostPort(resolvedHost)
+		if err != nil {
+			targetHost = resolvedHost
+		}
+		if host != targetHost {
+			return net.JoinHostPort(targetHost, port)
+		}
+		return addr
+	}
+
 	// If we don't enable http/2, then using a custom DialTLSConext is the best choice.
 	// It can improve performance by not using a compatibility layer.
 	if !ctx.Bool("http2") {
-		dialer := &tls.Dialer{NetDialer: netD, Config: tlsConfig}
-		return newClientTransport(ctx, withDialTLSContext(dialer.DialContext))
+		tlsDialer := &tls.Dialer{NetDialer: netD, Config: tlsConfig}
+		h1Dialer := func(ctx context.Context, network, addr string) (net.Conn, error) {
+			dialAddr := getDialAddr(addr)
+			return tlsDialer.DialContext(ctx, network, dialAddr)
+		}
+		return newClientTransport(ctx, withDialTLSContext(h1Dialer))
 	}
 
 	tr := &http.Transport{
-		Proxy:                 http.ProxyFromEnvironment,
-		DialContext:           netD.DialContext,
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+			dialAddr := getDialAddr(addr)
+			return netD.DialContext(ctx, network, dialAddr)
+		},
 		MaxIdleConnsPerHost:   ctx.Int("concurrent"),
 		WriteBufferSize:       ctx.Int("sndbuf"), // Configure beyond 4KiB default buffer size.
 		ReadBufferSize:        ctx.Int("rcvbuf"), // Configure beyond 4KiB default buffer size.

cli/client_tls.go

@@ -19,13 +19,22 @@ package cli
 
 import (
 	"crypto/tls"
+	"net"
 	"net/http"
 	"os"
 
 	"github.com/minio/cli"
 )
 
-func clientTransportTLS(ctx *cli.Context, localIP string) http.RoundTripper {
+func clientTransportTLS(ctx *cli.Context, localIP, resolvedHost, originalHost string) http.RoundTripper {
+	var sni string
+	if originalHost != "" {
+		if h, _, err := net.SplitHostPort(originalHost); err == nil {
+			sni = h
+		} else {
+			sni = originalHost
+		}
+	}
 	// Keep TLS config.
 	tlsConfig := &tls.Config{
 		RootCAs: mustGetSystemCertPool(),
@@ -34,12 +43,20 @@ func clientTransportTLS(ctx *cli.Context, localIP string) http.RoundTripper {
 		// Can't use TLSv1.1 because of RC4 cipher usage
 		MinVersion:         tls.VersionTLS12,
 		InsecureSkipVerify: ctx.Bool("insecure"),
+		ServerName:         sni,
 		ClientSessionCache: tls.NewLRUClientSessionCache(1024), // up to 1024 nodes
 	}
 
 	if ctx.Bool("debug") {
 		tlsConfig.KeyLogWriter = os.Stdout
 	}
 
-	return newClientTransport(ctx, withTLSConfig(tlsConfig), withLocalAddr(localIP))
+	dialer := makeDialer(localIP)
+	opts := []transportOption{withTLSConfig(tlsConfig)}
+	if originalHost != "" {
+		opts = append(opts, withResolveHost(resolvedHost, originalHost, dialer, true))
+	} else {
+		opts = append(opts, withLocalAddr(localIP))
+	}
+	return newClientTransport(ctx, opts...)
 }

cli/client_transport.go

@@ -69,6 +69,36 @@ func withDialTLSContext(dialer func(ctx context.Context, network, addr string) (
 	}
 }
 
+// withResolveHost rewrites the dial address from the logical hostname to the
+// resolved IP when --resolve-host is active. Only activates when originalHost != "".
+// Proxy connections are not rewritten (if addr doesn't match our target, it's a proxy).
+func withResolveHost(resolvedHost, originalHost string, dialer *net.Dialer, isTLS bool) transportOption {
+	return func(transport *http.Transport) {
+		if originalHost == "" || resolvedHost == "" {
+			return
+		}
+		targetHost, _, err := net.SplitHostPort(resolvedHost)
+		if err != nil {
+			targetHost = resolvedHost
+		}
+		transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+			host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				host = addr
+				port = "80"
+				if isTLS {
+					port = "443"
+				}
+			}
+			dialAddr := addr
+			if host != targetHost {
+				dialAddr = net.JoinHostPort(targetHost, port)
+			}
+			return dialer.DialContext(ctx, network, dialAddr)
+		}
+	}
+}
+
 func newClientTransport(ctx *cli.Context, options ...transportOption) http.RoundTripper {
 	tr := &http.Transport{
 		Proxy:                 http.ProxyFromEnvironment,

cli/flags.go

@@ -217,7 +217,7 @@ var ioFlags = []cli.Flag{
 	},
 	cli.BoolFlag{
 		Name:   "resolve-host",
-		Usage:  "Resolve the host(s) ip(s) (including multiple A/AAAA records). This can break SSL certificates, use --insecure if so",
+		Usage:  "Resolve the host(s) ip(s) (including multiple A/AAAA records)",
 		Hidden: true,
 	},
 	cli.IntFlag{