oidc-idp/handlers/error.go

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/*
Copyright 2020, 2021 Jan Dittberner
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package handlers
import (
"context"
"fmt"
"html/template"
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"io/fs"
"net/http"
"git.cacert.org/oidc_idp/services"
"github.com/nicksnyder/go-i18n/v2/i18n"
log "github.com/sirupsen/logrus"
)
type errorKey int
const (
errorBucketKey errorKey = iota
)
type ErrorDetails struct {
ErrorMessage string
ErrorDetails []string
ErrorCode string
Error error
}
type ErrorBucket struct {
errorDetails *ErrorDetails
templates *template.Template
logger *log.Logger
bundle *i18n.Bundle
messageCatalog *services.MessageCatalog
}
func (b *ErrorBucket) serveHTTP(w http.ResponseWriter, r *http.Request) {
if b.errorDetails != nil {
accept := r.Header.Get("Accept-Language")
localizer := i18n.NewLocalizer(b.bundle, accept)
err := b.templates.Lookup("base").Execute(w, map[string]interface{}{
"Title": b.messageCatalog.LookupMessage(
"ErrorTitle",
nil,
localizer,
),
"details": b.errorDetails,
})
if err != nil {
log.Errorf("error rendering error template: %v", err)
http.Error(
w,
http.StatusText(http.StatusInternalServerError),
http.StatusInternalServerError,
)
}
}
}
func GetErrorBucket(r *http.Request) *ErrorBucket {
return r.Context().Value(errorBucketKey).(*ErrorBucket)
}
// call this from your application's handler
func (b *ErrorBucket) AddError(details *ErrorDetails) {
b.errorDetails = details
}
type errorResponseWriter struct {
http.ResponseWriter
ctx context.Context
statusCode int
}
func (w *errorResponseWriter) WriteHeader(code int) {
w.statusCode = code
if code >= 400 {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
errorBucket := w.ctx.Value(errorBucketKey).(*ErrorBucket)
if errorBucket != nil && errorBucket.errorDetails == nil {
errorBucket.AddError(&ErrorDetails{
ErrorMessage: http.StatusText(code),
})
}
}
w.ResponseWriter.WriteHeader(code)
}
func (w *errorResponseWriter) Write(content []byte) (int, error) {
if w.statusCode > 400 {
errorBucket := w.ctx.Value(errorBucketKey).(*ErrorBucket)
if errorBucket != nil {
if errorBucket.errorDetails.ErrorDetails == nil {
errorBucket.errorDetails.ErrorDetails = make([]string, 0)
}
errorBucket.errorDetails.ErrorDetails = append(
errorBucket.errorDetails.ErrorDetails, string(content),
)
return len(content), nil
}
}
return w.ResponseWriter.Write(content)
}
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func ErrorHandling(handlerContext context.Context, logger *log.Logger, templateFS fs.FS) (func(http.Handler) http.Handler, error) {
errorTemplates, err := template.ParseFS(
templateFS,
"templates/base.gohtml",
"templates/errors.gohtml",
)
if err != nil {
return nil, err
}
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
errorBucket := &ErrorBucket{
templates: errorTemplates,
logger: logger,
bundle: services.GetI18nBundle(handlerContext),
messageCatalog: services.GetMessageCatalog(handlerContext),
}
ctx := context.WithValue(r.Context(), errorBucketKey, errorBucket)
interCeptingResponseWriter := &errorResponseWriter{
w,
ctx,
http.StatusOK,
}
next.ServeHTTP(
interCeptingResponseWriter,
r.WithContext(ctx),
)
errorBucket.serveHTTP(w, r)
})
}, nil
}
type errorHandler struct {
}
func (e *errorHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
_, _ = fmt.Fprintf(w, `
didumm %#v
`, r.URL.Query())
}
func NewErrorHandler() *errorHandler {
return &errorHandler{}
}