ced34bab1a
"ogg" is just a "container" format for audio and video. Golang's `DetectContentType` only reports "application/ogg" for potential ogg files. Actually it could do more "guess" to see whether it is a audio file or a video file.
144 lines
4.3 KiB
Go
144 lines
4.3 KiB
Go
// Copyright 2021 The Gitea Authors. All rights reserved.
|
|
// SPDX-License-Identifier: MIT
|
|
|
|
package typesniffer
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"io"
|
|
"net/http"
|
|
"regexp"
|
|
"strings"
|
|
|
|
"code.gitea.io/gitea/modules/util"
|
|
)
|
|
|
|
// Use at most this many bytes to determine Content Type.
|
|
const sniffLen = 1024
|
|
|
|
const (
|
|
// SvgMimeType MIME type of SVG images.
|
|
SvgMimeType = "image/svg+xml"
|
|
// ApplicationOctetStream MIME type of binary files.
|
|
ApplicationOctetStream = "application/octet-stream"
|
|
)
|
|
|
|
var (
|
|
svgComment = regexp.MustCompile(`(?s)<!--.*?-->`)
|
|
svgTagRegex = regexp.MustCompile(`(?si)\A\s*(?:(<!DOCTYPE\s+svg([\s:]+.*?>|>))\s*)*<svg\b`)
|
|
svgTagInXMLRegex = regexp.MustCompile(`(?si)\A<\?xml\b.*?\?>\s*(?:(<!DOCTYPE\s+svg([\s:]+.*?>|>))\s*)*<svg\b`)
|
|
)
|
|
|
|
// SniffedType contains information about a blobs type.
|
|
type SniffedType struct {
|
|
contentType string
|
|
}
|
|
|
|
// IsText etects if content format is plain text.
|
|
func (ct SniffedType) IsText() bool {
|
|
return strings.Contains(ct.contentType, "text/")
|
|
}
|
|
|
|
// IsImage detects if data is an image format
|
|
func (ct SniffedType) IsImage() bool {
|
|
return strings.Contains(ct.contentType, "image/")
|
|
}
|
|
|
|
// IsSvgImage detects if data is an SVG image format
|
|
func (ct SniffedType) IsSvgImage() bool {
|
|
return strings.Contains(ct.contentType, SvgMimeType)
|
|
}
|
|
|
|
// IsPDF detects if data is a PDF format
|
|
func (ct SniffedType) IsPDF() bool {
|
|
return strings.Contains(ct.contentType, "application/pdf")
|
|
}
|
|
|
|
// IsVideo detects if data is an video format
|
|
func (ct SniffedType) IsVideo() bool {
|
|
return strings.Contains(ct.contentType, "video/")
|
|
}
|
|
|
|
// IsAudio detects if data is an video format
|
|
func (ct SniffedType) IsAudio() bool {
|
|
return strings.Contains(ct.contentType, "audio/")
|
|
}
|
|
|
|
// IsRepresentableAsText returns true if file content can be represented as
|
|
// plain text or is empty.
|
|
func (ct SniffedType) IsRepresentableAsText() bool {
|
|
return ct.IsText() || ct.IsSvgImage()
|
|
}
|
|
|
|
// IsBrowsableBinaryType returns whether a non-text type can be displayed in a browser
|
|
func (ct SniffedType) IsBrowsableBinaryType() bool {
|
|
return ct.IsImage() || ct.IsSvgImage() || ct.IsPDF() || ct.IsVideo() || ct.IsAudio()
|
|
}
|
|
|
|
// GetMimeType returns the mime type
|
|
func (ct SniffedType) GetMimeType() string {
|
|
return strings.SplitN(ct.contentType, ";", 2)[0]
|
|
}
|
|
|
|
// DetectContentType extends http.DetectContentType with more content types. Defaults to text/unknown if input is empty.
|
|
func DetectContentType(data []byte) SniffedType {
|
|
if len(data) == 0 {
|
|
return SniffedType{"text/unknown"}
|
|
}
|
|
|
|
ct := http.DetectContentType(data)
|
|
|
|
if len(data) > sniffLen {
|
|
data = data[:sniffLen]
|
|
}
|
|
|
|
// SVG is unsupported by http.DetectContentType, https://github.com/golang/go/issues/15888
|
|
|
|
detectByHTML := strings.Contains(ct, "text/plain") || strings.Contains(ct, "text/html")
|
|
detectByXML := strings.Contains(ct, "text/xml")
|
|
if detectByHTML || detectByXML {
|
|
dataProcessed := svgComment.ReplaceAll(data, nil)
|
|
dataProcessed = bytes.TrimSpace(dataProcessed)
|
|
if detectByHTML && svgTagRegex.Match(dataProcessed) ||
|
|
detectByXML && svgTagInXMLRegex.Match(dataProcessed) {
|
|
ct = SvgMimeType
|
|
}
|
|
}
|
|
|
|
if strings.HasPrefix(ct, "audio/") && bytes.HasPrefix(data, []byte("ID3")) {
|
|
// The MP3 detection is quite inaccurate, any content with "ID3" prefix will result in "audio/mpeg".
|
|
// So remove the "ID3" prefix and detect again, if result is text, then it must be text content.
|
|
// This works especially because audio files contain many unprintable/invalid characters like `0x00`
|
|
ct2 := http.DetectContentType(data[3:])
|
|
if strings.HasPrefix(ct2, "text/") {
|
|
ct = ct2
|
|
}
|
|
}
|
|
|
|
if ct == "application/ogg" {
|
|
dataHead := data
|
|
if len(dataHead) > 256 {
|
|
dataHead = dataHead[:256] // only need to do a quick check for the file header
|
|
}
|
|
if bytes.Contains(dataHead, []byte("theora")) || bytes.Contains(dataHead, []byte("dirac")) {
|
|
ct = "video/ogg" // ogg is only used for some video formats, and it's not popular
|
|
} else {
|
|
ct = "audio/ogg" // for most cases, it is used as an audio container
|
|
}
|
|
}
|
|
return SniffedType{ct}
|
|
}
|
|
|
|
// DetectContentTypeFromReader guesses the content type contained in the reader.
|
|
func DetectContentTypeFromReader(r io.Reader) (SniffedType, error) {
|
|
buf := make([]byte, sniffLen)
|
|
n, err := util.ReadAtMost(r, buf)
|
|
if err != nil {
|
|
return SniffedType{}, fmt.Errorf("DetectContentTypeFromReader io error: %w", err)
|
|
}
|
|
buf = buf[:n]
|
|
|
|
return DetectContentType(buf), nil
|
|
}
|