80 lines
2.2 KiB
Go
80 lines
2.2 KiB
Go
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// Copyright 2013 The Go Authors. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd.
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package httputil
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import (
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"github.com/golang/gddo/httputil/header"
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"net/http"
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"strings"
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)
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// NegotiateContentEncoding returns the best offered content encoding for the
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// request's Accept-Encoding header. If two offers match with equal weight and
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// then the offer earlier in the list is preferred. If no offers are
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// acceptable, then "" is returned.
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func NegotiateContentEncoding(r *http.Request, offers []string) string {
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bestOffer := "identity"
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bestQ := -1.0
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specs := header.ParseAccept(r.Header, "Accept-Encoding")
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for _, offer := range offers {
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for _, spec := range specs {
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if spec.Q > bestQ &&
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(spec.Value == "*" || spec.Value == offer) {
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bestQ = spec.Q
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bestOffer = offer
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}
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}
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}
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if bestQ == 0 {
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bestOffer = ""
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}
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return bestOffer
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}
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// NegotiateContentType returns the best offered content type for the request's
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// Accept header. If two offers match with equal weight, then the more specific
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// offer is preferred. For example, text/* trumps */*. If two offers match
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// with equal weight and specificity, then the offer earlier in the list is
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// preferred. If no offers match, then defaultOffer is returned.
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func NegotiateContentType(r *http.Request, offers []string, defaultOffer string) string {
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bestOffer := defaultOffer
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bestQ := -1.0
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bestWild := 3
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specs := header.ParseAccept(r.Header, "Accept")
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for _, offer := range offers {
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for _, spec := range specs {
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switch {
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case spec.Q == 0.0:
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// ignore
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case spec.Q < bestQ:
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// better match found
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case spec.Value == "*/*":
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if spec.Q > bestQ || bestWild > 2 {
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bestQ = spec.Q
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bestWild = 2
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bestOffer = offer
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}
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case strings.HasSuffix(spec.Value, "/*"):
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if strings.HasPrefix(offer, spec.Value[:len(spec.Value)-1]) &&
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(spec.Q > bestQ || bestWild > 1) {
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bestQ = spec.Q
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bestWild = 1
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bestOffer = offer
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}
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default:
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if spec.Value == offer &&
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(spec.Q > bestQ || bestWild > 0) {
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bestQ = spec.Q
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bestWild = 0
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bestOffer = offer
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}
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}
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}
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}
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return bestOffer
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}
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