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gabriel-vasile · Jul 2, 2018 · 1b28fdf · 1b28fdf
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diff --git a/LICENSE b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 Gabriel Vasile
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
@@ -0,0 +1,31 @@
+<h1 align="center">
+  mimetype
+</h1>
+
+<h4 align="center">
+  A library for detecting mime types and extensions based on magic numbers
+</h4>
+
+## Installation
+```bash
+go get github.com/gabriel-vasile/mimetype
+
+
+## Usage
+The library exposes three functions you can use in order to detect a file type.
+```go
+func Detect(in []byte) (mime, extension string) {...}
+func DetectReader(r io.Reader) (mime, extension string, err error) {...}
+func DetectFile(file string) (mime, extension string, err error) {...}
+```
+See [Godoc](https://godoc.org/github.com/gabriel-vasile/mimetype) for full reference.
+
+## Structure
+<b>mimetype</b> uses an hierarchical structure to keep the matching functions.
+This reduces the number of calls needed for detecting the file type. The reason
+behind this choice is that there are file formats used as containers for other
+file formats. For example, Microsoft office files are just zip archives,
+containing specific metadata files.
+<div align="center">
+  <img alt="Header" src="mimetype.gif" width="88%">
+</div>
diff --git a/matchers/archive.go b/matchers/archive.go
@@ -0,0 +1,49 @@
+// Package matchers holds the matching functions used to find mime types
+package matchers
+
+import (
+	"archive/zip"
+	"bytes"
+)
+
+func Zip(in []byte) bool {
+	return len(in) > 3 &&
+		in[0] == 0x50 && in[1] == 0x4B &&
+		(in[2] == 0x3 || in[2] == 0x5 || in[2] == 0x7) &&
+		(in[3] == 0x4 || in[3] == 0x6 || in[3] == 0x8)
+}
+
+func SevenZ(in []byte) bool {
+	return bytes.Equal(in[:6], []byte{0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C})
+}
+
+func Epub(in []byte) bool {
+	if len(in) < 58 {
+		return false
+	}
+	in = in[30:58]
+
+	return bytes.Equal(in, []byte("mimetypeapplication/epub+zip"))
+}
+
+func Jar(in []byte) bool {
+	reader := bytes.NewReader(in)
+	zipr, err := zip.NewReader(reader, reader.Size())
+	if err != nil {
+		return false
+	}
+
+	return zipHasFile(zipr, "META-INF/MANIFEST.MF")
+}
+
+func Apk(in []byte) bool {
+	reader := bytes.NewReader(in)
+	zipr, err := zip.NewReader(reader, reader.Size())
+	if err != nil {
+		return false
+	}
+
+	return zipHasFile(zipr, "AndroidManifest.xml") &&
+		zipHasFile(zipr, "classes.dex") &&
+		zipHasFile(zipr, "resources.arsc")
+}
diff --git a/matchers/audio.go b/matchers/audio.go
@@ -0,0 +1,31 @@
+package matchers
+
+import "bytes"
+
+func Mp3(in []byte) bool {
+	return bytes.HasPrefix(in, []byte("\x49\x44\x33"))
+}
+
+func Flac(in []byte) bool {
+	return false
+}
+
+func Midi(in []byte) bool {
+	return false
+}
+
+func Ape(in []byte) bool {
+	return false
+}
+
+func MusePack(in []byte) bool {
+	return false
+}
+
+func Wav(in []byte) bool {
+	return false
+}
+
+func Aiff(in []byte) bool {
+	return false
+}
diff --git a/matchers/document.go b/matchers/document.go
@@ -0,0 +1,79 @@
+package matchers
+
+import "bytes"
+
+type htmlSignature []byte
+type xmlSignature []byte
+
+var htmlSignatures = []htmlSignature{
+	htmlSignature("<!DOCTYPE HTML"),
+	htmlSignature("<HTML"),
+	htmlSignature("<HEAD"),
+	htmlSignature("<SCRIPT"),
+	htmlSignature("<IFRAME"),
+	htmlSignature("<H1"),
+	htmlSignature("<DIV"),
+	htmlSignature("<FONT"),
+	htmlSignature("<TABLE"),
+	htmlSignature("<A"),
+	htmlSignature("<STYLE"),
+	htmlSignature("<TITLE"),
+	htmlSignature("<B"),
+	htmlSignature("<BODY"),
+	htmlSignature("<BR"),
+	htmlSignature("<P"),
+	htmlSignature("<!--"),
+}
+
+func Txt(in []byte) bool {
+	in = trimWS(in)
+	for _, b := range in {
+		if b <= 0x08 ||
+			b == 0x0B ||
+			0x0E <= b && b <= 0x1A ||
+			0x1C <= b && b <= 0x1F {
+			return false
+		}
+	}
+
+	return true
+}
+
+func Html(in []byte) bool {
+	in = trimWS(in)
+
+	for _, hSig := range htmlSignatures {
+		if detectHtml(in, hSig) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func Xml(in []byte) bool {
+	in = trimWS(in)
+	return bytes.HasPrefix(in, []byte("<?xml"))
+}
+
+func detectHtml(in []byte, hSig htmlSignature) bool {
+	if len(in) < len(hSig)+1 {
+		return false
+	}
+
+	for i, b := range hSig {
+		db := in[i]
+		if 'A' <= b && b <= 'Z' {
+			db &= 0xDF
+		}
+		if b != db {
+			return false
+		}
+	}
+	// Next byte must be space or right angle bracket.
+	if db := in[len(hSig)]; db != ' ' && db != '>' {
+		return false
+	}
+
+	return true
+}
diff --git a/matchers/image.go b/matchers/image.go
@@ -0,0 +1,46 @@
+package matchers
+
+import "bytes"
+
+func Png(in []byte) bool {
+	return bytes.Equal(in[:8], []byte{0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A})
+}
+
+func Jpg(in []byte) bool {
+	return bytes.Equal(in[:3], []byte{0xFF, 0xD8, 0xFF})
+}
+
+func Gif(in []byte) bool {
+	return bytes.HasPrefix(in, []byte("GIF87a")) ||
+		bytes.HasPrefix(in, []byte("GIF89a"))
+}
+
+func Webp(in []byte) bool {
+	return len(in) > 11 &&
+		in[8] == 0x57 && in[9] == 0x45 &&
+		in[10] == 0x42 && in[11] == 0x50
+}
+
+func Bmp(in []byte) bool {
+	return len(in) > 1 &&
+		in[0] == 0x42 &&
+		in[1] == 0x4D
+}
+
+func Ps(in []byte) bool {
+	return bytes.HasPrefix(in, []byte("%!PS-Adobe-"))
+}
+
+func Psd(in []byte) bool {
+	return bytes.HasPrefix(in, []byte("8BPS"))
+}
+
+func Ico(in []byte) bool {
+	return len(in) > 3 &&
+		in[0] == 0x00 && in[1] == 0x00 &&
+		in[2] == 0x01 && in[3] == 0x00
+}
+
+func Tiff(in []byte) bool {
+	return false
+}
diff --git a/matchers/matchers.go b/matchers/matchers.go
@@ -0,0 +1,26 @@
+package matchers
+
+import "bytes"
+
+func Dummy(_ []byte) bool {
+	return true
+}
+
+func Pdf(in []byte) bool {
+	return bytes.Equal(in[:4], []byte{0x25, 0x50, 0x44, 0x46})
+}
+
+func trimWS(in []byte) []byte {
+	firstNonWS := 0
+	for ; firstNonWS < len(in) && isWS(in[firstNonWS]); firstNonWS++ {
+	}
+	return in[firstNonWS:]
+}
+
+func isWS(b byte) bool {
+	switch b {
+	case '\t', '\n', '\x0c', '\r', ' ':
+		return true
+	}
+	return false
+}
diff --git a/matchers/ms_office.go b/matchers/ms_office.go
@@ -0,0 +1,61 @@
+package matchers
+
+import (
+	"archive/zip"
+	"bytes"
+	"path/filepath"
+)
+
+func Xlsx(in []byte) bool {
+	return checkMsOfficex(in, "xl")
+}
+
+func Docx(in []byte) bool {
+	return checkMsOfficex(in, "word")
+}
+
+func Pptx(in []byte) bool {
+	return checkMsOfficex(in, "ppt")
+}
+
+func Doc(in []byte) bool {
+	return false
+}
+
+func Ppt(in []byte) bool {
+	return false
+}
+
+func Xls(in []byte) bool {
+	return false
+}
+
+func checkMsOfficex(in []byte, folder string) bool {
+	reader := bytes.NewReader(in)
+	zipr, err := zip.NewReader(reader, reader.Size())
+	if err != nil {
+		return false
+	}
+
+	return zipHasFile(zipr, "[Content_Types].xml") && zipHasFolder(zipr, folder)
+}
+
+func zipHasFolder(r *zip.Reader, folder string) bool {
+	for _, f := range r.File {
+		if filepath.Dir(f.Name) == folder {
+			return true
+		}
+	}
+
+	return false
+}
+
+func zipHasFile(r *zip.Reader, file string) bool {
+	for _, f := range r.File {
+		if f.Name == file {
+			return true
+		}
+	}
+
+	return false
+}