add custom error templates

experimental/middleware/middleware.go

@@ -4,11 +4,33 @@
 package experimental
 
 import (
+	"embed"
 	"net/http"
 
 	"github.com/corazawaf/coraza/v3"
 )
 
+//go:embed error_template.html error_template.html
+var embededTemplates embed.FS
+
+var (
+	errorTemplate        []byte
+	interruptionTemplate []byte
+)
+
+func init() {
+	var err error
+	errorTemplate, err = embededTemplates.ReadFile("error_template.html")
+	if err != nil {
+		panic(err)
+	}
+	interruptionTemplate, err = embededTemplates.ReadFile("interruption_template.html")
+	if err != nil {
+		panic(err)
+	}
+
+}
+
 // Options represents the options for the experimental middleware
 type Options struct {
 	// EnforceBlocking enables the blocking of requests that are interrupted
@@ -41,6 +63,21 @@ type Options struct {
 	// If the rate is 0, the middleware will not sample
 	// If the rate is 100, the middleware will sample all requests
 	SamplingRate int
+
+	// CustomInterruptionTemplate represents the custom interruption template
+	// If the interruption is not processed, the middleware will use a default
+	// Interruption template supports variables in macro expansion format: %{var}
+	// Variables are:
+	//   - transaction_id
+	CustomInterruptionTemplate []byte
+
+	// CustomErrorTemplate represents the custom error template
+	// If the middleware fails to process the request, it will use a default
+	// Error template supports variables in macro expansion format: %{var}
+	// Variables are:
+	//   - transaction_id
+	//   - error
+	CustomErrorTemplate []byte
 }
 
 // DefaultOptions returns the default options for the middleware
@@ -64,6 +101,11 @@ func DefaultOptions(waf coraza.WAF) Options {
 // Keys are:
 //   - coraza_transaction: types.Transaction
 //   - coraza_interruption: types.Interruption
+//   - coraza_error: error
+//
+// If Coraza fails to process the request, the middleware will return a generic error.
+// The next handler will not be executed and coraza_error will be available under
+// the request context.
 //
 // The middleware will flush the request body and it will consume
 // the response in case ProcessResponse Option is enabled.