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