✨ Add parameter to configure the ban page Content-Type response header (#325)

* Add parameter to configure Ban Response Content-Type

* Add testing for new BanResponseContentType parameter

* Ensure there is a fallback to default Content-Type is user provided empty value

* Set Content-Type even if banTemplate is nil

* Add more edge cases for testing ban response Content-Type

* Add CR/LF validation for BanResponseContentType

* Add CaptchaResponseContentType to allow separate Content-Type configuration for captcha responses

* Add testing for new CaptchaResponseContentType

* Update README

* Split nil and CR/LF response Content-Type value validation into separate function

* Throw error instead of setting the default in case of empty parameter declaration

* Update testing accordingly

* ✨ remove HTML from var name, add tests and infer content type from filePath

* 🍱 fix lint ?

* 🍱 fix lint

* 🍱 fix lint

* 🍱 fix lint + naming

* 🍱 fix lint

* 🍱 fuck lint

---------

Co-authored-by: maxlerebourg <maxlerebourg@gmail.com>

README.md

@@ -513,14 +513,14 @@ make run
   - int64
   - default: 1800 (= 30 minutes)
   - Period after validation of a captcha before a new validation is required if Crowdsec decision is still valid
-- CaptchaHTMLFilePath
+- CaptchaFilePath
   - string
   - default: /captcha.html
-  - Path where the captcha template is stored
-- BanHTMLFilePath
+  - Path where the captcha template is stored. The Content-Type header is automatically inferred from the file extension.
+- BanFilePath
   - string
   - default: ""
-  - Path where the ban html file is stored (default empty ""=disabled)
+  - Path where the ban file is stored (default empty ""=disabled). The Content-Type header is automatically inferred from the file extension.
 - TraceHeadersCustomName
   - string
   - default: ""

bouncer.go

@@ -9,7 +9,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	htmltemplate "html/template"
 	"io"
 	"log/slog"
 	"net/http"
@@ -110,7 +109,8 @@ type Bouncer struct {
 	crowdsecStreamRoute     string
 	crowdsecHeader          string
 	redisUnreachableBlock   bool
-	banTemplate             *htmltemplate.Template
+	banTemplate             *template.Template
+	banTemplateContentType  string
 	traceCustomHeader       string
 	clientPoolStrategy      *ip.PoolStrategy
 	serverPoolStrategy      *ip.PoolStrategy
@@ -123,10 +123,18 @@ type Bouncer struct {
 
 // New creates the crowdsec bouncer plugin.
 //
-//nolint:nestif,gocyclo,gocognit
+//nolint:nestif,gocyclo,gocognit,funlen,maintidx
 func New(_ context.Context, next http.Handler, config *configuration.Config, name string) (http.Handler, error) {
 	config.LogLevel = strings.ToUpper(config.LogLevel)
 	log := logger.NewWithFormat(config.LogLevel, config.LogFilePath, config.LogFormat)
+
+	if config.BanFilePath == "" && config.BanHTMLFilePath != "" {
+		config.BanFilePath = config.BanHTMLFilePath
+	}
+	if config.CaptchaHTMLFilePath != "" {
+		config.CaptchaFilePath = config.CaptchaHTMLFilePath
+	}
+
 	err := configuration.ValidateParams(config, log)
 	if err != nil {
 		log.Error("New:validateParams " + err.Error())
@@ -184,9 +192,10 @@ func New(_ context.Context, next http.Handler, config *configuration.Config, nam
 		}
 	}
 
-	var banTemplate *htmltemplate.Template
-	if config.BanHTMLFilePath != "" {
-		banTemplate, _ = configuration.GetHTMLTemplate(config.BanHTMLFilePath)
+	var banTemplate *template.Template
+	var banTemplateContentType string
+	if config.BanFilePath != "" {
+		banTemplate, banTemplateContentType, _ = configuration.GetTemplate(config.BanFilePath)
 	}
 
 	bouncer := &Bouncer{
@@ -219,6 +228,7 @@ func New(_ context.Context, next http.Handler, config *configuration.Config, nam
 		remediationStatusCode:   config.RemediationStatusCode,
 		redisUnreachableBlock:   config.RedisCacheUnreachableBlock,
 		banTemplate:             banTemplate,
+		banTemplateContentType:  banTemplateContentType,
 		traceCustomHeader:       config.TraceHeadersCustomName,
 		crowdsecStreamRoute:     crowdsecStreamRoute,
 		crowdsecHeader:          crowdsecHeader,
@@ -276,7 +286,7 @@ func New(_ context.Context, next http.Handler, config *configuration.Config, nam
 		config.CaptchaSiteKey,
 		config.CaptchaSecretKey,
 		config.RemediationHeadersCustomName,
-		config.CaptchaHTMLFilePath,
+		config.CaptchaFilePath,
 		config.CaptchaGracePeriodSeconds,
 	)
 	if err != nil {
@@ -433,14 +443,9 @@ func (bouncer *Bouncer) handleBanServeHTTP(rw http.ResponseWriter, req *http.Req
 	if bouncer.remediationCustomHeader != "" {
 		rw.Header().Set(bouncer.remediationCustomHeader, "ban")
 	}
-	if bouncer.banTemplate == nil {
+	rw.Header().Set("Content-Type", bouncer.banTemplateContentType)
 	rw.WriteHeader(bouncer.remediationStatusCode)
-		return
-	}
-	rw.Header().Set("Content-Type", "text/html; charset=utf-8")
-	rw.WriteHeader(bouncer.remediationStatusCode)
-
-	if req.Method == http.MethodHead {
+	if bouncer.banTemplate == nil || req.Method == http.MethodHead {
 		return
 	}
 	templateData := map[string]string{

bouncer_logging_test.go

@@ -32,13 +32,13 @@ func getTestConfig() *configuration.Config {
 		ForwardedHeadersTrustedIPs:           []string{"127.0.0.1"},
 		ForwardedHeadersCustomName:           "",
 		RemediationStatusCode:                403,
-		BanHTMLFilePath:                      "",
+		BanFilePath:                          "",
 		RemediationHeadersCustomName:         "",
 		CaptchaProvider:                      "",
 		CaptchaSiteKey:                       "",
 		CaptchaSecretKey:                     "",
 		CaptchaGracePeriodSeconds:            1,
-		CaptchaHTMLFilePath:                  "",
+		CaptchaFilePath:                      "",
 		RedisCacheEnabled:                    false,
 		RedisCacheHost:                       "",
 		RedisCachePassword:                   "",

bouncer_test.go

@@ -2,7 +2,6 @@ package crowdsec_bouncer_traefik_plugin //nolint:revive,stylecheck
 
 import (
 	"context"
-	htmltemplate "html/template"
 	"net/http"
 	"net/http/httptest"
 	"reflect"
@@ -190,11 +189,11 @@ func Test_crowdsecQuery(t *testing.T) {
 
 func TestHandleBanServeHTTPWithDifferentMethods(t *testing.T) {
 	html := "<html>You are banned</html>"
-	banTemplate, _ := htmltemplate.New("html").Parse(html)
+	banTemplate, _ := template.New("html").Delims("{{", "}}").Parse(html)
 	tests := []struct {
 		name              string
 		method            string
-		banTemplate       *htmltemplate.Template
+		banTemplate       *template.Template
 		expectBodyContent bool
 	}{
 		{
@@ -235,6 +234,7 @@ func TestHandleBanServeHTTPWithDifferentMethods(t *testing.T) {
 				remediationStatusCode:   http.StatusForbidden,
 				remediationCustomHeader: "X-Test-Remediation",
 				banTemplate:             tt.banTemplate,
+				banTemplateContentType:  "text/html; charset=utf-8",
 			}
 
 			rw := httptest.NewRecorder()
@@ -269,6 +269,50 @@ func TestHandleBanServeHTTPWithDifferentMethods(t *testing.T) {
 	}
 }
 
+func TestHandleBanServeHTTPContentType(t *testing.T) {
+	html := "<html>You are banned</html>"
+	banTemplate, _ := template.New("html").Delims("{{", "}}").Parse(html)
+	tests := []struct {
+		name                   string
+		banTemplate            *template.Template
+		banTemplateContentType string
+	}{
+		{
+			name:                   "Default HTML content type",
+			banTemplate:            banTemplate,
+			banTemplateContentType: "text/html; charset=utf-8",
+		},
+		{
+			name:                   "Custom JSON content type",
+			banTemplate:            banTemplate,
+			banTemplateContentType: "application/json",
+		},
+		{
+			name:                   "Content type set even when banTemplate is nil",
+			banTemplate:            nil,
+			banTemplateContentType: "application/json",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			bouncer := &Bouncer{
+				remediationStatusCode:  http.StatusForbidden,
+				banTemplate:            tt.banTemplate,
+				banTemplateContentType: tt.banTemplateContentType,
+			}
+
+			rw := httptest.NewRecorder()
+			req := &http.Request{Method: http.MethodGet}
+			bouncer.handleBanServeHTTP(rw, req, "0.0.0.0", "TEST")
+
+			if got := rw.Header().Get("Content-Type"); got != tt.banTemplateContentType {
+				t.Errorf("Expected Content-Type %q, got %q", tt.banTemplateContentType, got)
+			}
+		})
+	}
+}
+
 func TestCaptchaMethodBasedLogic(t *testing.T) {
 	tests := []struct {
 		name              string

examples/custom-ban-page/README.md

@@ -9,11 +9,11 @@ This can be usefull as some browser (Firefox for instance) return a 403 blank we
 
 ```yaml
   labels:
-      # Define ban HTML file path
-      - "traefik.http.middlewares.crowdsec.plugin.bouncer.banHtmlFilePath=/ban.html"
+      # Define ban file path
+      - "traefik.http.middlewares.crowdsec.plugin.bouncer.banFilePath=/ban.html"
 ```
 
-The ban HTML file must be present in the Traefik container (bind mounted or added during a custom build).  
+The ban file must be present in the Traefik container (bind mounted or added during a custom build).  
 It is not directly accessible from Traefik even when importing the plugin, so [download](https://raw.githubusercontent.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/master/ban.html) it locally to expose it to Traefik.
 
 ```yaml 

examples/custom-ban-page/docker-compose.yml

@@ -42,8 +42,8 @@ services:
       - "traefik.http.middlewares.crowdsec.plugin.bouncer.enabled=true"
       - "traefik.http.middlewares.crowdsec.plugin.bouncer.crowdseclapikey=40796d93c2958f9e58345514e67740e5"
       - "traefik.http.middlewares.crowdsec.plugin.bouncer.loglevel=DEBUG"
-      # Define ban HTML file path
-      - "traefik.http.middlewares.crowdsec.plugin.bouncer.banHtmlFilePath=/ban.html"
+      # Define ban file path
+      - "traefik.http.middlewares.crowdsec.plugin.bouncer.banFilePath=/ban.html"
 
   crowdsec:
     image: crowdsecurity/crowdsec:v1.6.1-2

pkg/captcha/captcha.go

@@ -4,11 +4,11 @@ package captcha
 import (
 	"encoding/json"
 	"fmt"
-	"html/template"
 	"log/slog"
 	"net/http"
 	"net/url"
 	"strings"
+	"text/template"
 
 	cache "github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/pkg/cache"
 	configuration "github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/pkg/configuration"
@@ -21,7 +21,8 @@ type Client struct {
 	secretKey               string
 	remediationCustomHeader string
 	gracePeriodSeconds      int64
-	captchaTemplate         *template.Template
+	templateContentType     string
+	template                *template.Template
 	cacheClient             *cache.Client
 	httpClient              *http.Client
 	log                     *slog.Logger
@@ -74,8 +75,9 @@ func (c *Client) New(log *slog.Logger, cacheClient *cache.Client, httpClient *ht
 	c.siteKey = siteKey
 	c.secretKey = secretKey
 	c.remediationCustomHeader = remediationCustomHeader
-	html, _ := configuration.GetHTMLTemplate(captchaTemplatePath)
-	c.captchaTemplate = html
+	template, contentType, _ := configuration.GetTemplate(captchaTemplatePath)
+	c.template = template
+	c.templateContentType = contentType
 	c.gracePeriodSeconds = gracePeriodSeconds
 	c.log = log
 	c.httpClient = httpClient
@@ -100,12 +102,12 @@ func (c *Client) ServeHTTP(rw http.ResponseWriter, r *http.Request, remoteIP str
 		http.Redirect(rw, r, r.URL.String(), http.StatusFound)
 		return
 	}
-	rw.Header().Set("Content-Type", "text/html; charset=utf-8")
+	rw.Header().Set("Content-Type", c.templateContentType)
 	if c.remediationCustomHeader != "" {
 		rw.Header().Set(c.remediationCustomHeader, "captcha")
 	}
 	rw.WriteHeader(http.StatusOK)
-	err = c.captchaTemplate.Execute(rw, map[string]string{
+	err = c.template.Execute(rw, map[string]string{
 		"SiteKey":     c.siteKey,
 		"FrontendJS":  c.infoProvider.js,
 		"FrontendKey": c.infoProvider.key,

pkg/configuration/configuration.go

@@ -6,7 +6,6 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
-	"html/template"
 	"log/slog"
 	"net/http"
 	"net/url"
@@ -15,6 +14,7 @@ import (
 	"reflect"
 	"regexp"
 	"strings"
+	"text/template"
 
 	ip "github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/pkg/ip"
 )
@@ -99,8 +99,10 @@ type Config struct {
 	RedisCachePasswordFile                     string   `json:"redisCachePasswordFile,omitempty"`
 	RedisCacheDatabase                         string   `json:"redisCacheDatabase,omitempty"`
 	RedisCacheUnreachableBlock                 bool     `json:"redisCacheUnreachableBlock,omitempty"`
-	BanHTMLFilePath                            string   `json:"banHtmlFilePath,omitempty"`
-	CaptchaHTMLFilePath                        string   `json:"captchaHtmlFilePath,omitempty"`
+	BanHTMLFilePath                            string   `json:"banHtmlFilePath,omitempty"` // Deprecated: Keep it for historical compatibility
+	BanFilePath                                string   `json:"banFilePath,omitempty"`
+	CaptchaHTMLFilePath                        string   `json:"captchaHtmlFilePath,omitempty"` // Deprecated: Keep it for historical compatibility
+	CaptchaFilePath                            string   `json:"captchaFilePath,omitempty"`
 	CaptchaProvider                            string   `json:"captchaProvider,omitempty"`
 	CaptchaCustomJsURL                         string   `json:"captchaCustomJsUrl,omitempty"`
 	CaptchaCustomValidateURL                   string   `json:"captchaCustomValidateUrl,omitempty"`
@@ -159,8 +161,8 @@ func New() *Config {
 		CaptchaSiteKey:                  "",
 		CaptchaSecretKey:                "",
 		CaptchaGracePeriodSeconds:       1800,
-		CaptchaHTMLFilePath:             "/captcha.html",
-		BanHTMLFilePath:                 "",
+		CaptchaFilePath:                 "/captcha.html",
+		BanFilePath:                     "",
 		TraceHeadersCustomName:          "",
 		RemediationHeadersCustomName:    "",
 		ForwardedHeadersCustomName:      "X-Forwarded-For",
@@ -201,28 +203,50 @@ func GetVariable(config *Config, key string) (string, error) {
 	return strings.TrimSpace(value), nil
 }
 
-// GetHTMLTemplate get compiled HTML template.
-func GetHTMLTemplate(path string) (*template.Template, error) {
-	var err error
+func getContentTypeFromPath(path string) string {
 	if path == "" {
-		return nil, errors.New("no html template provided")
+		return ""
 	}
+	ext := strings.ToLower(filepath.Ext(path))
+	contentTypeMap := map[string]string{
+		".html": "text/html; charset=utf-8",
+		".htm":  "text/html; charset=utf-8",
+		".json": "application/json",
+		".txt":  "text/plain",
+		".xml":  "application/xml",
+		".js":   "application/javascript",
+		".css":  "text/css",
+	}
+	if contentType, ok := contentTypeMap[ext]; ok {
+		return contentType
+	}
+	// Default to HTML for backward compatibility
+	return "text/html; charset=utf-8"
+}
+
+// GetTemplate get compiled template with {{ and }} delimiters.
+// Uses text/template for all file types to avoid HTML escaping issues.
+func GetTemplate(path string) (*template.Template, string, error) {
+	if path == "" {
+		return nil, "", errors.New("no template file provided")
+	}
+	contentType := getContentTypeFromPath(path)
 	//nolint:gosec
 	b, err := os.ReadFile(path)
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
-	html := string(b)
-	compiledTemplate, err := template.New("html").Parse(html)
+	content := string(b)
+	compiledTemplate, err := template.New(filepath.Base(path)).Delims("{{", "}}").Parse(content)
 	if err != nil {
-		return nil, fmt.Errorf("impossible to compile html template: %w", err)
+		return nil, "", fmt.Errorf("impossible to compile template %s: %w", path, err)
 	}
-	return compiledTemplate, nil
+	return compiledTemplate, contentType, nil
 }
 
 // ValidateParams validate all the param gave by user.
 //
-//nolint:gocyclo,gocognit
+//nolint:gocyclo,gocognit,nestif
 func ValidateParams(config *Config, log *slog.Logger) error {
 	if err := validateParamsRequired(config); err != nil {
 		return err
@@ -260,12 +284,14 @@ func ValidateParams(config *Config, log *slog.Logger) error {
 		if _, err := GetVariable(config, "CaptchaSecretKey"); err != nil {
 			return err
 		}
-		if _, err := GetHTMLTemplate(config.CaptchaHTMLFilePath); err != nil {
+		if config.CaptchaFilePath != "" {
+			if _, _, err := GetTemplate(config.CaptchaFilePath); err != nil {
 				return err
 			}
 		}
-	if config.BanHTMLFilePath != "" {
-		if _, err := GetHTMLTemplate(config.BanHTMLFilePath); err != nil {
+	}
+	if config.BanFilePath != "" {
+		if _, _, err := GetTemplate(config.BanFilePath); err != nil {
 			return err
 		}
 	}

pkg/configuration/configuration_test.go

@@ -301,3 +301,28 @@ func Test_GetTLSConfigCrowdsec(t *testing.T) {
 		})
 	}
 }
+
+func Test_getContentTypeFromPath(t *testing.T) {
+	tests := []struct {
+		name     string
+		path     string
+		expected string
+	}{
+		{name: "HTML file with .html extension", path: "/ban.html", expected: "text/html; charset=utf-8"},
+		{name: "JSON file", path: "/ban.json", expected: "application/json"},
+		{name: "Text file", path: "/ban.txt", expected: "text/plain"},
+		{name: "File with mixed case extension", path: "/ban.HtMl", expected: "text/html; charset=utf-8"},
+		{name: "Unknown extension defaults to HTML", path: "/ban.xyz", expected: "text/html; charset=utf-8"},
+		{name: "File without extension", path: "/ban", expected: "text/html; charset=utf-8"},
+		{name: "Empty path", path: "", expected: ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := getContentTypeFromPath(tt.path)
+			if got != tt.expected {
+				t.Errorf("GetContentTypeFromPath(%q) = %q, want %q", tt.path, got, tt.expected)
+			}
+		})
+	}
+}

tests/e2e/mock/scenarios/captcha/run.sh

@@ -16,6 +16,9 @@ body() {
   echo "[$SCENARIO] captcha page must be served once the decision is polled (200 + marker)"
   wait_for_body_contains "http://127.0.0.1:${WEB_PORT}/foo" "E2E_CAPTCHA_PAGE_MARKER" 15 -H "X-Forwarded-For: 1.2.3.4"
 
+  echo "[$SCENARIO] captcha response Content-Type is HTML"
+  assert_header "http://127.0.0.1:${WEB_PORT}/foo" Content-Type "text/html; charset=utf-8" -H "X-Forwarded-For: 1.2.3.4"
+
   echo "[$SCENARIO] captcha response is HTTP 200 (the captcha page itself, not a 403)"
   assert_status "http://127.0.0.1:${WEB_PORT}/foo" 200 -H "X-Forwarded-For: 1.2.3.4"
 

tests/e2e/mock/scenarios/custom-ban-page/ban.html

@@ -1,8 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head><meta charset="utf-8"><title>E2E ban marker</title></head>
-<body>
-<h1 id="e2e-ban-marker">E2E_CUSTOM_BAN_PAGE_MARKER</h1>
-<p>IP: {{ .ClientIP }} reason: {{ .RemediationReason }}</p>
-</body>
-</html>

tests/e2e/mock/scenarios/custom-ban-page/ban.json

@@ -0,0 +1,4 @@
+{
+  "marker": "E2E_CUSTOM_BAN_PAGE_MARKER",
+  "body": "IP: {{ .ClientIP }}, reason: {{ .RemediationReason }}, trace: {{ .TraceID }}"
+}

tests/e2e/mock/scenarios/custom-ban-page/dynamic.yml

@@ -24,5 +24,6 @@ http:
           crowdsecLapiKey: "@@APIKEY@@"
           forwardedHeadersTrustedIps:
             - "127.0.0.1/32"
-          banHtmlFilePath: "@@SCENARIO_DIR@@/ban.html"
+          banFilePath: "@@SCENARIO_DIR@@/ban.json"
           remediationHeadersCustomName: "X-E2E-Remediation"
+          traceHeadersCustomName: x-trace

tests/e2e/mock/scenarios/custom-ban-page/run.sh

@@ -15,11 +15,14 @@ body() {
   wait_for_status "http://127.0.0.1:${WEB_PORT}/foo" 403 15 -H "X-Forwarded-For: 1.2.3.4"
 
   echo "[$SCENARIO] banned response Content-Type is HTML"
-  assert_header "http://127.0.0.1:${WEB_PORT}/foo" Content-Type "text/html; charset=utf-8" -H "X-Forwarded-For: 1.2.3.4"
+  assert_header "http://127.0.0.1:${WEB_PORT}/foo" Content-Type "application/json" -H "X-Forwarded-For: 1.2.3.4"
 
   echo "[$SCENARIO] banned response body contains the custom marker"
   assert_body_contains "http://127.0.0.1:${WEB_PORT}/foo" "E2E_CUSTOM_BAN_PAGE_MARKER" -H "X-Forwarded-For: 1.2.3.4"
 
+  echo "[$SCENARIO] banned response body contains the IP and reason from templating"
+  assert_body_contains "http://127.0.0.1:${WEB_PORT}/foo" "IP: 1.2.3.4, reason: LAPI, trace: 0123456789" -H "X-Forwarded-For: 1.2.3.4" -H "X-Trace: 0123456789"
+
   echo "[$SCENARIO] banned response carries the custom remediation header (remediationHeadersCustomName)"
   assert_header "http://127.0.0.1:${WEB_PORT}/foo" X-E2E-Remediation "ban" -H "X-Forwarded-For: 1.2.3.4"
 }