95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
package headers
|
|
|
|
import (
|
|
"bufio"
|
|
"fmt"
|
|
"net"
|
|
"net/http"
|
|
|
|
"github.com/traefik/traefik/v2/pkg/log"
|
|
)
|
|
|
|
type responseModifier struct {
|
|
r *http.Request
|
|
w http.ResponseWriter
|
|
|
|
headersSent bool // whether headers have already been sent
|
|
code int // status code, must default to 200
|
|
|
|
modifier func(*http.Response) error // can be nil
|
|
modified bool // whether modifier has already been called for the current request
|
|
modifierErr error // returned by modifier call
|
|
}
|
|
|
|
// modifier can be nil.
|
|
func newResponseModifier(w http.ResponseWriter, r *http.Request, modifier func(*http.Response) error) *responseModifier {
|
|
return &responseModifier{
|
|
r: r,
|
|
w: w,
|
|
modifier: modifier,
|
|
code: http.StatusOK,
|
|
}
|
|
}
|
|
|
|
func (w *responseModifier) WriteHeader(code int) {
|
|
if w.headersSent {
|
|
return
|
|
}
|
|
defer func() {
|
|
w.code = code
|
|
w.headersSent = true
|
|
}()
|
|
|
|
if w.modifier == nil || w.modified {
|
|
w.w.WriteHeader(code)
|
|
return
|
|
}
|
|
|
|
resp := http.Response{
|
|
Header: w.w.Header(),
|
|
Request: w.r,
|
|
}
|
|
|
|
if err := w.modifier(&resp); err != nil {
|
|
w.modifierErr = err
|
|
// we are propagating when we are called in Write, but we're logging anyway,
|
|
// because we could be called from another place which does not take care of
|
|
// checking w.modifierErr.
|
|
log.WithoutContext().Errorf("Error when applying response modifier: %v", err)
|
|
w.w.WriteHeader(http.StatusInternalServerError)
|
|
return
|
|
}
|
|
|
|
w.modified = true
|
|
w.w.WriteHeader(code)
|
|
}
|
|
|
|
func (w *responseModifier) Header() http.Header {
|
|
return w.w.Header()
|
|
}
|
|
|
|
func (w *responseModifier) Write(b []byte) (int, error) {
|
|
w.WriteHeader(w.code)
|
|
if w.modifierErr != nil {
|
|
return 0, w.modifierErr
|
|
}
|
|
|
|
return w.w.Write(b)
|
|
}
|
|
|
|
// Hijack hijacks the connection.
|
|
func (w *responseModifier) Hijack() (net.Conn, *bufio.ReadWriter, error) {
|
|
if h, ok := w.w.(http.Hijacker); ok {
|
|
return h.Hijack()
|
|
}
|
|
|
|
return nil, nil, fmt.Errorf("not a hijacker: %T", w.w)
|
|
}
|
|
|
|
// Flush sends any buffered data to the client.
|
|
func (w *responseModifier) Flush() {
|
|
if flusher, ok := w.w.(http.Flusher); ok {
|
|
flusher.Flush()
|
|
}
|
|
}
|