81 lines
2 KiB
Go
81 lines
2 KiB
Go
// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
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// SPDX-License-Identifier: Apache-2.0
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package sanitizer
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import (
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"fmt"
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"strconv"
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"strings"
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)
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type ImageCandidate struct {
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ImageURL string
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Descriptor string
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}
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type ImageCandidates []*ImageCandidate
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func (c ImageCandidates) String() string {
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var htmlCandidates []string
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for _, imageCandidate := range c {
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var htmlCandidate string
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if imageCandidate.Descriptor != "" {
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htmlCandidate = fmt.Sprintf(`%s %s`, imageCandidate.ImageURL, imageCandidate.Descriptor)
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} else {
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htmlCandidate = imageCandidate.ImageURL
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}
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htmlCandidates = append(htmlCandidates, htmlCandidate)
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}
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return strings.Join(htmlCandidates, ", ")
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}
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// ParseSrcSetAttribute returns the list of image candidates from the set.
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// https://html.spec.whatwg.org/#parse-a-srcset-attribute
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func ParseSrcSetAttribute(attributeValue string) (imageCandidates ImageCandidates) {
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unparsedCandidates := strings.Split(attributeValue, ", ")
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for _, unparsedCandidate := range unparsedCandidates {
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if candidate, err := parseImageCandidate(unparsedCandidate); err == nil {
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imageCandidates = append(imageCandidates, candidate)
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}
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}
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return imageCandidates
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}
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func parseImageCandidate(input string) (*ImageCandidate, error) {
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input = strings.TrimSpace(input)
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parts := strings.Split(strings.TrimSpace(input), " ")
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nbParts := len(parts)
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if nbParts > 2 || nbParts == 0 {
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return nil, fmt.Errorf(`srcset: invalid number of descriptors`)
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}
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if nbParts == 2 {
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if !isValidWidthOrDensityDescriptor(parts[1]) {
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return nil, fmt.Errorf(`srcset: invalid descriptor`)
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}
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return &ImageCandidate{ImageURL: parts[0], Descriptor: parts[1]}, nil
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}
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return &ImageCandidate{ImageURL: parts[0]}, nil
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}
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func isValidWidthOrDensityDescriptor(value string) bool {
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if value == "" {
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return false
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}
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lastChar := value[len(value)-1:]
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if lastChar != "w" && lastChar != "x" {
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return false
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}
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_, err := strconv.ParseFloat(value[0:len(value)-1], 32)
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return err == nil
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}
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