Use Accept request header instead of user agent to figure out non-browser clients. Funny fact, I borrowed the idea from a fork ('8a3e142cf3/router/generic.go (L33)')

README.md

@@ -47,7 +47,7 @@ curl -6 ifconfig.es
 ## Endpoints
 
 - https://ifconfig.es/
-- https://ifconfig.es/json
+- https://ifconfig.es/json (this is the same as `curl -H "Accept: application/json" https://ifconfig.es/`)
 - https://ifconfig.es/geo
   - https://ifconfig.es/geo/city
   - https://ifconfig.es/geo/country

cmd/whatismyip.go

@@ -17,6 +17,7 @@ import (
 	"github.com/dcarrillo/whatismyip/router"
 
 	"github.com/gin-gonic/gin"
+	"github.com/unrolled/secure"
 )
 
 var (
@@ -138,6 +139,28 @@ func setupEngine() {
 	engine = gin.New()
 	engine.Use(gin.LoggerWithFormatter(httputils.GetLogFormatter))
 	engine.Use(gin.Recovery())
+	if setting.App.EnableSecureHeaders {
+		engine.Use(addSecureHeaders())
+	}
 	_ = engine.SetTrustedProxies(nil)
 	engine.TrustedPlatform = setting.App.TrustedHeader
 }
+
+func addSecureHeaders() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		err := secure.New(secure.Options{
+			BrowserXssFilter:   true,
+			ContentTypeNosniff: true,
+			FrameDeny:          true,
+		}).Process(c.Writer, c.Request)
+		if err != nil {
+			c.Abort()
+			return
+		}
+
+		// Avoid header rewrite if response is a redirection.
+		if status := c.Writer.Status(); status > 300 && status < 399 {
+			c.Abort()
+		}
+	}
+}

go.mod

@@ -4,9 +4,10 @@ go 1.18
 
 require (
 	github.com/gin-gonic/gin v1.7.7
-	github.com/oschwald/maxminddb-golang v1.8.0
+	github.com/oschwald/maxminddb-golang v1.9.0
 	github.com/stretchr/testify v1.7.1
 	github.com/testcontainers/testcontainers-go v0.12.0
+	github.com/unrolled/secure v1.10.0
 )
 
 require (
@@ -15,10 +16,10 @@ require (
 	github.com/Microsoft/hcsshim v0.9.2 // indirect
 	github.com/cenkalti/backoff v2.2.1+incompatible // indirect
 	github.com/containerd/cgroups v1.0.3 // indirect
-	github.com/containerd/containerd v1.6.1 // indirect
+	github.com/containerd/containerd v1.6.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/docker/distribution v2.8.1+incompatible // indirect
-	github.com/docker/docker v20.10.13+incompatible // indirect
+	github.com/docker/docker v20.10.14+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect
@@ -41,19 +42,19 @@ require (
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.0.2 // indirect
-	github.com/opencontainers/runc v1.1.0 // indirect
+	github.com/opencontainers/runc v1.1.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sirupsen/logrus v1.8.1 // indirect
 	github.com/ugorji/go/codec v1.2.7 // indirect
 	go.opencensus.io v0.23.0 // indirect
-	golang.org/x/crypto v0.0.0-20220315160706-3147a52a75dd // indirect
+	golang.org/x/crypto v0.0.0-20220331220935-ae2d96664a29 // indirect
-	golang.org/x/net v0.0.0-20220225172249-27dd8689420f // indirect
+	golang.org/x/net v0.0.0-20220401154927-543a649e0bdd // indirect
-	golang.org/x/sys v0.0.0-20220319134239-a9b59b0215f8 // indirect
+	golang.org/x/sys v0.0.0-20220330033206-e17cdc41300f // indirect
 	golang.org/x/text v0.3.7 // indirect
-	google.golang.org/genproto v0.0.0-20220317150908-0efb43f6373e // indirect
+	google.golang.org/genproto v0.0.0-20220401170504-314d38edb7de // indirect
 	google.golang.org/grpc v1.45.0 // indirect
-	google.golang.org/protobuf v1.27.1 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

integration-tests/integration_test.go

@@ -34,6 +34,7 @@ func buildContainer() testcontainers.ContainerRequest {
 			"-tls-crt", "/tmp/server.pem",
 			"-tls-key", "/tmp/server.key",
 			"-trusted-header", "X-Real-IP",
+			"-enable-secure-headers",
 		},
 		ExposedPorts: []string{"8000:8000", "8001:8001"},
 		WaitingFor:   wait.ForLog("Starting TLS server listening on :8001"),
@@ -69,16 +70,18 @@ func TestContainerIntegration(t *testing.T) {
 	}()
 
 	http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
-	for _, url := range []string{"http://localhost:8000/json", "https://localhost:8001/json"} {
+	for _, url := range []string{"http://localhost:8000", "https://localhost:8001"} {
-		resp, _ := http.Get(url)
+		client := &http.Client{}
+		req, _ := http.NewRequest("GET", url, nil)
+		req.Header.Set("Accept", "application/json")
+		resp, _ := client.Do(req)
 		assert.Equal(t, 200, resp.StatusCode)
 
-		var dat router.JSONResponse
 		body, err := ioutil.ReadAll(resp.Body)
 		if err != nil {
 			log.Fatal(err)
 		}
 
-		assert.NoError(t, json.Unmarshal(body, &dat))
+		assert.NoError(t, json.Unmarshal(body, &router.JSONResponse{}))
 	}
 }

internal/setting/app.go

@@ -27,6 +27,7 @@ type settings struct {
 	TLSCrtPath          string
 	TLSKeyPath          string
 	TrustedHeader       string
+	EnableSecureHeaders bool
 	Server              serverSettings
 	version             bool
 }
@@ -74,6 +75,12 @@ func Setup(args []string) (output string, err error) {
 		"Trusted request header for remote IP (e.g. X-Real-IP)",
 	)
 	flags.BoolVar(&App.version, "version", false, "Output version information and exit")
+	flags.BoolVar(
+		&App.EnableSecureHeaders,
+		"enable-secure-headers",
+		false,
+		"Add sane security-related headers to every response",
+	)
 
 	err = flags.Parse(args)
 	if err != nil {

internal/setting/app_test.go

@@ -76,6 +76,7 @@ func TestParseFlags(t *testing.T) {
 				TLSCrtPath:          "",
 				TLSKeyPath:          "",
 				TrustedHeader:       "",
+				EnableSecureHeaders: false,
 				Server: serverSettings{
 					ReadTimeout:  10 * time.Second,
 					WriteTimeout: 10 * time.Second,
@@ -95,6 +96,7 @@ func TestParseFlags(t *testing.T) {
 				TLSCrtPath:          "",
 				TLSKeyPath:          "",
 				TrustedHeader:       "",
+				EnableSecureHeaders: false,
 				Server: serverSettings{
 					ReadTimeout:  10 * time.Second,
 					WriteTimeout: 10 * time.Second,
@@ -117,6 +119,7 @@ func TestParseFlags(t *testing.T) {
 				TLSCrtPath:          "/crt-path",
 				TLSKeyPath:          "/key-path",
 				TrustedHeader:       "",
+				EnableSecureHeaders: false,
 				Server: serverSettings{
 					ReadTimeout:  10 * time.Second,
 					WriteTimeout: 10 * time.Second,
@@ -126,7 +129,7 @@ func TestParseFlags(t *testing.T) {
 		{
 			[]string{
 				"-geoip2-city", "/city-path", "-geoip2-asn", "/asn-path",
-				"-trusted-header", "header",
+				"-trusted-header", "header", "-enable-secure-headers",
 			},
 			settings{
 				GeodbPath: geodbPath{
@@ -139,6 +142,7 @@ func TestParseFlags(t *testing.T) {
 				TLSCrtPath:          "",
 				TLSKeyPath:          "",
 				TrustedHeader:       "header",
+				EnableSecureHeaders: true,
 				Server: serverSettings{
 					ReadTimeout:  10 * time.Second,
 					WriteTimeout: 10 * time.Second,

router/generic.go

@@ -4,7 +4,6 @@ import (
 	"net"
 	"net/http"
 	"path/filepath"
-	"regexp"
 
 	"github.com/dcarrillo/whatismyip/internal/httputils"
 	"github.com/dcarrillo/whatismyip/internal/setting"
@@ -12,8 +11,6 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-const userAgentPattern = `curl|wget|libwww-perl|python|ansible-httpget|HTTPie|WindowsPowerShell|http_request|Go-http-client|^$`
-
 // JSONResponse maps data as json
 type JSONResponse struct {
 	IP              string      `json:"ip"`
@@ -33,15 +30,17 @@ type JSONResponse struct {
 }
 
 func getRoot(ctx *gin.Context) {
-	reg := regexp.MustCompile(userAgentPattern)
+	switch ctx.NegotiateFormat(gin.MIMEPlain, gin.MIMEHTML, gin.MIMEJSON) {
-	if reg.Match([]byte(ctx.Request.UserAgent())) {
+	case gin.MIMEHTML:
-		ctx.String(http.StatusOK, ctx.ClientIP())
-	} else {
 		name := "home"
 		if setting.App.TemplatePath != "" {
 			name = filepath.Base(setting.App.TemplatePath)
 		}
 		ctx.HTML(http.StatusOK, name, jsonOutput(ctx))
+	case gin.MIMEJSON:
+		getJSON(ctx)
+	default:
+		ctx.String(http.StatusOK, ctx.ClientIP()+"\n")
 	}
 }
 

router/generic_test.go

@@ -9,31 +9,80 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestIP4RootFromCli(t *testing.T) {
+func TestRootContentType(t *testing.T) {
-	uas := []string{
+	tests := []struct {
-		"",
+		name     string
-		"curl",
+		accepted string
-		"wget",
+		expected string
-		"libwww-perl",
+	}{
-		"python",
+		{
-		"ansible-httpget",
+			name:     "Accept wildcard",
-		"HTTPie",
+			accepted: "*/*",
-		"WindowsPowerShell",
+			expected: contentType.text,
-		"http_request",
+		},
-		"Go-http-client",
+		{
+			name:     "Bogus accept",
+			accepted: "bogus/plain",
+			expected: contentType.text,
+		},
+		{
+			name:     "Accept plain text",
+			accepted: "text/plain",
+			expected: contentType.text,
+		},
+		{
+			name:     "Accept json",
+			accepted: "application/json",
+			expected: contentType.json,
+		},
 	}
-
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			req, _ := http.NewRequest("GET", "/", nil)
-	req.Header.Set("X-Real-IP", testIP.ipv4)
+			req.Header.Set(trustedHeader, testIP.ipv4)
-
+			req.Header.Set("Accept", tt.accepted)
-	for _, ua := range uas {
-		req.Header.Set("User-Agent", ua)
 
 			w := httptest.NewRecorder()
 			app.ServeHTTP(w, req)
 
 			assert.Equal(t, 200, w.Code)
-		assert.Equal(t, testIP.ipv4, w.Body.String())
+			assert.Equal(t, tt.expected, w.Header().Get("Content-Type"))
+		})
+	}
+}
+
+func TestGetIP(t *testing.T) {
+	expected := testIP.ipv4 + "\n"
+	tests := []struct {
+		name     string
+		accepted string
+	}{
+		{
+			name:     "No browser",
+			accepted: "*/*",
+		},
+		{
+			name:     "Bogus accept",
+			accepted: "bogus/plain",
+		},
+		{
+			name:     "Plain accept",
+			accepted: "text/plain",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req, _ := http.NewRequest("GET", "/", nil)
+			req.Header.Set(trustedHeader, testIP.ipv4)
+			req.Header.Set("Accept", tt.accepted)
+
+			w := httptest.NewRecorder()
+			app.ServeHTTP(w, req)
+
+			assert.Equal(t, 200, w.Code)
+			assert.Equal(t, expected, w.Body.String())
+			assert.Equal(t, contentType.text, w.Header().Get("Content-Type"))
+		})
 	}
 }
 
@@ -50,7 +99,7 @@ func TestHost(t *testing.T) {
 func TestClientPort(t *testing.T) {
 	req, _ := http.NewRequest("GET", "/client-port", nil)
 	req.RemoteAddr = net.JoinHostPort(testIP.ipv4, "1000")
-	req.Header.Set("X-Real-IP", testIP.ipv4)
+	req.Header.Set(trustedHeader, testIP.ipv4)
 
 	w := httptest.NewRecorder()
 	app.ServeHTTP(w, req)
@@ -71,31 +120,44 @@ func TestNotFound(t *testing.T) {
 }
 
 func TestJSON(t *testing.T) {
-	expectedIPv4 := `{"client_port":"1000","ip":"81.2.69.192","ip_version":4,"country":"United Kingdom","country_code":"GB","city":"London","latitude":51.5142,"longitude":-0.0931,"postal_code":"","time_zone":"Europe/London","asn":0,"asn_organization":"","host":"test","headers":{"X-Real-Ip":["81.2.69.192"]}}`
+	type args struct {
-	expectedIPv6 := `{"asn":3352, "asn_organization":"TELEFONICA DE ESPANA", "city":"", "client_port":"1000", "country":"", "country_code":"", "headers":{"X-Real-Ip":["2a02:9000::1"]}, "host":"test", "ip":"2a02:9000::1", "ip_version":6, "latitude":0, "longitude":0, "postal_code":"", "time_zone":""}`
+		ip string
-
+	}
+	tests := []struct {
+		name     string
+		args     args
+		expected string
+	}{
+		{
+			name: "IPv4",
+			args: args{
+				ip: testIP.ipv4,
+			},
+			expected: jsonIPv4,
+		},
+		{
+			name: "IPv6",
+			args: args{
+				ip: testIP.ipv6,
+			},
+			expected: jsonIPv6,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			req, _ := http.NewRequest("GET", "/json", nil)
-	req.RemoteAddr = net.JoinHostPort(testIP.ipv4, "1000")
+			req.RemoteAddr = net.JoinHostPort(tt.args.ip, "1000")
 			req.Host = "test"
-	req.Header.Set("X-Real-IP", testIP.ipv4)
+			req.Header.Set(trustedHeader, tt.args.ip)
 
 			w := httptest.NewRecorder()
 			app.ServeHTTP(w, req)
 
 			assert.Equal(t, 200, w.Code)
 			assert.Equal(t, contentType.json, w.Header().Get("Content-Type"))
-	assert.JSONEq(t, expectedIPv4, w.Body.String())
+			assert.JSONEq(t, tt.expected, w.Body.String())
-
+		})
-	req.RemoteAddr = net.JoinHostPort(testIP.ipv6, "1000")
+	}
-	req.Host = "test"
-	req.Header.Set("X-Real-IP", testIP.ipv6)
-
-	w = httptest.NewRecorder()
-	app.ServeHTTP(w, req)
-
-	assert.Equal(t, 200, w.Code)
-	assert.Equal(t, contentType.json, w.Header().Get("Content-Type"))
-	assert.JSONEq(t, expectedIPv6, w.Body.String())
 }
 
 func TestAll(t *testing.T) {
@@ -120,7 +182,7 @@ X-Real-Ip: 81.2.69.192
 	req, _ := http.NewRequest("GET", "/all", nil)
 	req.RemoteAddr = net.JoinHostPort(testIP.ipv4, "1000")
 	req.Host = "test"
-	req.Header.Set("X-Real-IP", testIP.ipv4)
+	req.Header.Set(trustedHeader, testIP.ipv4)
 	req.Header.Set("Header1", "one")
 
 	w := httptest.NewRecorder()

router/setup_test.go

@@ -16,6 +16,7 @@ type testIPs struct {
 }
 
 type contentTypes struct {
+	html string
 	text string
 	json string
 }
@@ -29,9 +30,12 @@ var (
 		ipv6ASN: "2a02:a800::1",
 	}
 	contentType = contentTypes{
+		html: "content-type: text/html; charset=utf-8",
 		text: "text/plain; charset=utf-8",
 		json: "application/json; charset=utf-8",
 	}
+	jsonIPv4 = `{"client_port":"1000","ip":"81.2.69.192","ip_version":4,"country":"United Kingdom","country_code":"GB","city":"London","latitude":51.5142,"longitude":-0.0931,"postal_code":"","time_zone":"Europe/London","asn":0,"asn_organization":"","host":"test","headers":{"X-Real-Ip":["81.2.69.192"]}}`
+	jsonIPv6 = `{"asn":3352, "asn_organization":"TELEFONICA DE ESPANA", "city":"", "client_port":"1000", "country":"", "country_code":"", "headers":{"X-Real-Ip":["2a02:9000::1"]}, "host":"test", "ip":"2a02:9000::1", "ip_version":6, "latitude":0, "longitude":0, "postal_code":"", "time_zone":""}`
 )
 
 const trustedHeader = "X-Real-IP"