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