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package httptoo
import (
"compress/gzip"
"io"
"net/http"
"strings"
)
type gzipResponseWriter struct {
io.Writer
http.ResponseWriter
haveWritten bool
}
var _ http.ResponseWriter = &gzipResponseWriter{}
func (w *gzipResponseWriter) Write(b []byte) (int, error) {
if w.haveWritten {
goto write
}
w.haveWritten = true
if w.Header().Get("Content-Type") != "" {
goto write
}
if type_ := http.DetectContentType(b); type_ != "application/octet-stream" {
w.Header().Set("Content-Type", type_)
}
write:
return w.Writer.Write(b)
}
// Gzips response body if the request says it'll allow it.
func GzipHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") || w.Header().Get("Content-Encoding") != "" || w.Header().Get("Vary") != "" {
h.ServeHTTP(w, r)
return
}
w.Header().Set("Content-Encoding", "gzip")
w.Header().Set("Vary", "Accept-Encoding")
gz := gzip.NewWriter(w)
defer gz.Close()
h.ServeHTTP(&gzipResponseWriter{
Writer: gz,
ResponseWriter: w,
}, r)
})
}
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