feat: enable HTTP redirection

README.md

@@ -157,7 +157,16 @@ When the flag `-keystore` is provided, Slider will store a new KeyPair in disk,
 By default, Slider listens in port `8080`. Specify any other port using this flag.
 
 ##### `-template`:
-Mimic default web page and HTTP header of web server passed as parameter.
+Mimic "server" HTTP Response Header, web page and status code of web server passed as parameter.
+
+Apache and Nginx are presented with their default web pages and a 200 status code. Other templates might be presented
+in the form of error pages with their respective status code.
+
+##### `-redirect`:
+A redirect parameter must be at least a URL with a valid scheme and host (`http[s]://<host>[:<port>]`).
+
+HTTP connections will be redirected to the given URL while Slider connections will proceed as usual.
+Can be used in combination with `-template` to include a server header in the response headers.
 
 ##### `-verbose`:
 Choose the log level verbosity between debug, info, warn and error. When verbosity is set to `off` only non labeled and
@@ -431,7 +440,16 @@ a different Slider Server. This is useful when we want to be able to authorize s
 A connection from a Server with a fingerprint not successfully verified will be rejected.
 
 ##### `-template`:
-Mimic default web page and HTTP header of web server passed as parameter.
+Mimic "server" HTTP Response Header, web page and status code of web server passed as parameter.
+
+Apache and Nginx are presented with their default web pages and a 200 status code. Other templates might be presented 
+in the form of error pages with their respective status code. 
+
+##### `-redirect`:
+A redirect parameter must be at least a URL with a valid scheme and host (`http[s]://<host>[:<port>]`).
+
+HTTP connections will be redirected to the given URL while Slider connections will proceed as usual. 
+Can be used in combination with `-template` to include a server header in the response headers.
 
 #### Reverse Client Flags
 

client/client.go

@@ -48,6 +48,7 @@ type client struct {
 	isListener        bool
 	firstRun          bool
 	webTemplate       web.Template
+	webRedirect       string
 }
 
 const clientHelp = `
@@ -74,7 +75,8 @@ func NewClient(args []string) {
 	port := clientFlags.Int("port", 8081, "Listener Port")
 	address := clientFlags.String("address", "0.0.0.0", "Address the Listener will bind to")
 	retry := clientFlags.Bool("retry", false, "Retries reconnection indefinitely")
-	webTemplate := clientFlags.String("template", "", "Mimic web server page [apache|iis|nginx|tomcat]")
+	webTemplate := clientFlags.String("template", "default", "Mimic web server page [apache|iis|nginx|tomcat]")
+	webRedirect := clientFlags.String("redirect", "", "Redirect incoming HTTP connections to given URL")
 	clientFlags.Usage = func() {
 		fmt.Println(clientHelp)
 		clientFlags.PrintDefaults()
@@ -145,12 +147,21 @@ func NewClient(args []string) {
 	if *listener {
 		c.isListener = *listener
 
+		c.Logger.Debugf("Using \"%s\" web server template", *webTemplate)
 		t, tErr := web.GetTemplate(*webTemplate)
 		if tErr != nil {
 			c.Logger.Errorf("%v", tErr)
 		}
 		c.webTemplate = t
 
+		if *webRedirect != "" {
+			if wErr := web.CheckURL(*webRedirect); wErr != nil {
+				c.Logger.Fatalf("Redirect: %v", wErr)
+			}
+			c.webRedirect = *webRedirect
+			c.Logger.Debugf("Redirecting incomming HTTP requests to \"%s\"", c.webRedirect)
+		}
+
 		fmtAddress := fmt.Sprintf("%s:%d", *address, *port)
 		clientAddr, rErr := net.ResolveTCPAddr("tcp", fmtAddress)
 		if rErr != nil {
@@ -222,6 +233,9 @@ func flagSanityCheck(clientFlags *flag.FlagSet) error {
 		if conf.FlagIsDefined(clientFlags, "template") {
 			flagExclusion = append(flagExclusion, "-template")
 		}
+		if conf.FlagIsDefined(clientFlags, "redirect") {
+			flagExclusion = append(flagExclusion, "-redirect")
+		}
 		argNumber := len(clientFlags.Args())
 		if argNumber != 1 {
 			return fmt.Errorf("%s client requires exactly one valid server address as an argument", clientType)

client/handler.go

@@ -13,10 +13,16 @@ func (c *client) handleHTTPConn(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	w.Header().Add("server", c.webTemplate.ServerHeader)
+
+	if c.webRedirect != "" {
+		http.Redirect(w, r, c.webRedirect, http.StatusFound)
+		return
+	}
+
 	var wErr error
 	switch r.URL.Path {
 	case "/":
-		w.Header().Add("server", c.webTemplate.ServerHeader)
 		w.WriteHeader(c.webTemplate.StatusCode)
 		_, wErr = w.Write([]byte(c.webTemplate.HtmlTemplate))
 	default:

pkg/web/web.go

@@ -3,6 +3,7 @@ package web
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 	"strings"
 )
 
@@ -34,18 +35,31 @@ var (
 			ServerHeader: "Apache Tomcat",
 			StatusCode:   http.StatusNotFound,
 		},
+		"default": {
+			HtmlTemplate: "OK",
+			StatusCode:   http.StatusOK,
+			ServerHeader: "",
+		},
 	}
 )
 
 func GetTemplate(n string) (Template, error) {
 	t, ok := enabledTemplates[strings.ToLower(n)]
 	if !ok {
-		return Template{
-			HtmlTemplate: "OK",
-			StatusCode:   http.StatusOK,
-			ServerHeader: "",
-		}, fmt.Errorf("template not found, using default")
+		return enabledTemplates["default"], fmt.Errorf("template not found, using default")
 	}
 
 	return t, nil
 }
+
+func CheckURL(u string) error {
+	pURL, uErr := url.Parse(u)
+	if uErr != nil {
+		return fmt.Errorf("not a valid URL")
+	}
+	if pURL.Scheme == "" || pURL.Host == "" {
+		return fmt.Errorf("expecting a full URL including scheme and host")
+	}
+
+	return nil
+}

server/handler.go

@@ -16,10 +16,16 @@ func (s *server) handleHTTPClient(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	w.Header().Add("server", s.webTemplate.ServerHeader)
+
+	if s.webRedirect != "" {
+		http.Redirect(w, r, s.webRedirect, http.StatusFound)
+		return
+	}
+
 	var wErr error
 	switch r.URL.Path {
 	case "/":
-		w.Header().Add("server", s.webTemplate.ServerHeader)
 		w.WriteHeader(s.webTemplate.StatusCode)
 		_, wErr = w.Write([]byte(s.webTemplate.HtmlTemplate))
 	default:

server/server.go

@@ -51,6 +51,7 @@ type server struct {
 	certSaveOn        bool
 	keepalive         time.Duration
 	webTemplate       web.Template
+	webRedirect       string
 }
 
 func NewServer(args []string) {
@@ -64,7 +65,8 @@ func NewServer(args []string) {
 	certJarFile := serverFlags.String("certs", "", "Path of a valid slider-certs json file")
 	keyStore := serverFlags.Bool("keystore", false, "Store Server key for later use")
 	keyPath := serverFlags.String("keypath", "", "Path for reading or storing a Server key")
-	webTemplate := serverFlags.String("template", "", "Mimic web server page [apache|iis|nginx|tomcat]")
+	webTemplate := serverFlags.String("template", "default", "Mimic web server page [apache|iis|nginx|tomcat]")
+	webRedirect := serverFlags.String("redirect", "", "Redirect incoming HTTP connections to given URL")
 	serverFlags.Usage = func() {
 		fmt.Println(serverHelp)
 		serverFlags.PrintDefaults()
@@ -179,6 +181,14 @@ func NewServer(args []string) {
 	}
 	s.webTemplate = t
 
+	if *webRedirect != "" {
+		if wErr := web.CheckURL(*webRedirect); wErr != nil {
+			s.Logger.Fatalf("Redirect: %v", wErr)
+		}
+		s.webRedirect = *webRedirect
+		s.Logger.Debugf("Redirect incomming HTTP requests to \"%s\"", s.webRedirect)
+	}
+
 	fmtAddress := fmt.Sprintf("%s:%d", *address, *port)
 	serverAddr, rErr := net.ResolveTCPAddr("tcp", fmtAddress)
 	if rErr != nil {