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