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package staticpages
import (
"encoding/json"
"fmt"
"net/http"
"os"
"path/filepath"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"gitlab.com/gitlab-org/gitlab/workhorse/internal/helper"
)
var (
staticErrorResponses = promauto.NewCounterVec(
prometheus.CounterOpts{
Name: "gitlab_workhorse_static_error_responses",
Help: "How many HTTP responses have been changed to a static error page, by HTTP status code.",
},
[]string{"code"},
)
)
type ErrorFormat int
const (
ErrorFormatHTML ErrorFormat = iota
ErrorFormatJSON
ErrorFormatText
)
type errorPageResponseWriter struct {
rw http.ResponseWriter
status int
hijacked bool
path string
format ErrorFormat
}
func (s *errorPageResponseWriter) Header() http.Header {
return s.rw.Header()
}
func (s *errorPageResponseWriter) Write(data []byte) (int, error) {
if s.status == 0 {
s.WriteHeader(http.StatusOK)
}
if s.hijacked {
return len(data), nil
}
return s.rw.Write(data)
}
func (s *errorPageResponseWriter) WriteHeader(status int) {
if s.status != 0 {
return
}
s.status = status
if s.status < 400 || s.status > 599 || s.rw.Header().Get("X-GitLab-Custom-Error") != "" {
s.rw.WriteHeader(status)
return
}
var contentType string
var data []byte
switch s.format {
case ErrorFormatText:
contentType, data = s.writeText()
case ErrorFormatJSON:
contentType, data = s.writeJSON()
default:
contentType, data = s.writeHTML()
}
if contentType == "" {
s.rw.WriteHeader(status)
return
}
s.hijacked = true
staticErrorResponses.WithLabelValues(fmt.Sprintf("%d", s.status)).Inc()
helper.SetNoCacheHeaders(s.rw.Header())
s.rw.Header().Set("Content-Type", contentType)
s.rw.Header().Set("Content-Length", fmt.Sprintf("%d", len(data)))
s.rw.Header().Del("Transfer-Encoding")
s.rw.WriteHeader(s.status)
s.rw.Write(data)
}
func (s *errorPageResponseWriter) writeHTML() (string, []byte) {
if s.rw.Header().Get("Content-Type") != "application/json" {
errorPageFile := filepath.Join(s.path, fmt.Sprintf("%d.html", s.status))
// check if custom error page exists, serve this page instead
if data, err := os.ReadFile(errorPageFile); err == nil {
return "text/html; charset=utf-8", data
}
}
return "", nil
}
func (s *errorPageResponseWriter) writeJSON() (string, []byte) {
message, err := json.Marshal(map[string]interface{}{"error": http.StatusText(s.status), "status": s.status})
if err != nil {
return "", nil
}
return "application/json; charset=utf-8", append(message, "\n"...)
}
func (s *errorPageResponseWriter) writeText() (string, []byte) {
return "text/plain; charset=utf-8", []byte(http.StatusText(s.status) + "\n")
}
func (s *errorPageResponseWriter) flush() {
s.WriteHeader(http.StatusOK)
}
func (st *Static) ErrorPagesUnless(disabled bool, format ErrorFormat, handler http.Handler) http.Handler {
if disabled {
return handler
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
rw := errorPageResponseWriter{
rw: w,
path: st.DocumentRoot,
format: format,
}
defer rw.flush()
handler.ServeHTTP(&rw, r)
})
}
|