92 lines
2.0 KiB
Go
92 lines
2.0 KiB
Go
package urls
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import (
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"bytes"
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"encoding/base64"
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"strings"
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"unicode/utf8"
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"github.com/andybalholm/brotli"
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)
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const (
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htmlTagStart = 60 // Unicode `<`
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htmlTagEnd = 62 // Unicode `>`
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)
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// Taken from https://stackoverflow.com/a/64701836
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// Aggressively strips HTML tags from a string.
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// It will only keep anything between `>` and `<`.
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func stripHTMLTags(s string) string {
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// Setup a string builder and allocate enough memory for the new string.
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var builder strings.Builder
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builder.Grow(len(s) + utf8.UTFMax)
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in := false // True if we are inside an HTML tag.
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start := 0 // The index of the previous start tag character `<`
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end := 0 // The index of the previous end tag character `>`
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for i, c := range s {
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// If this is the last character and we are not in an HTML tag, save it.
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if (i+1) == len(s) && end >= start {
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builder.WriteString(s[end:])
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}
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// Keep going if the character is not `<` or `>`
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if c != htmlTagStart && c != htmlTagEnd {
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continue
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}
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if c == htmlTagStart {
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// Only update the start if we are not in a tag.
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// This make sure we strip out `<<br>` not just `<br>`
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if !in {
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start = i
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}
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in = true
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// Write the valid string between the close and start of the two tags.
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builder.WriteString(s[end:start])
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continue
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}
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// else c == htmlTagEnd
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in = false
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end = i + 1
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}
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s = builder.String()
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return s
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}
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func encodeDataURL(data []byte) (string, error) {
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bb := bytes.NewBuffer([]byte{})
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writer := brotli.NewWriter(bb)
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_, err := writer.Write(data)
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if err != nil {
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return "", err
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}
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err = writer.Close()
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if err != nil {
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return "", err
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}
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return base64.URLEncoding.EncodeToString(bb.Bytes()), nil
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}
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func decodeDataURL(data string) ([]byte, error) {
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decoded, err := base64.URLEncoding.DecodeString(data)
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if err != nil {
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return nil, err
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}
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output := make([]byte, 4096)
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bb := bytes.NewBuffer(decoded)
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reader := brotli.NewReader(bb)
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n, err := reader.Read(output)
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if err != nil {
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return nil, err
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}
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return output[:n], nil
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}
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