Add Debian package registry (#22854)

Co-authored-by: @awkwardbunny

This PR adds a Debian package registry. You can follow [this
tutorial](https://www.baeldung.com/linux/create-debian-package) to build
a *.deb package for testing. Source packages are not supported at the
moment and I did not find documentation of the architecture "all" and
how these packages should be treated.

---------

Co-authored-by: Brian Hong <brian@hongs.me>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/packages/debian/metadata_test.go

@@ -0,0 +1,171 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package debian
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"io"
+	"testing"
+
+	"github.com/blakesmith/ar"
+	"github.com/klauspost/compress/zstd"
+	"github.com/stretchr/testify/assert"
+	"github.com/ulikunitz/xz"
+)
+
+const (
+	packageName         = "gitea"
+	packageVersion      = "0:1.0.1-te~st"
+	packageArchitecture = "amd64"
+	packageAuthor       = "KN4CK3R"
+	description         = "Description with multiple lines."
+	projectURL          = "https://gitea.io"
+)
+
+func TestParsePackage(t *testing.T) {
+	createArchive := func(files map[string][]byte) io.Reader {
+		var buf bytes.Buffer
+		aw := ar.NewWriter(&buf)
+		aw.WriteGlobalHeader()
+		for filename, content := range files {
+			hdr := &ar.Header{
+				Name: filename,
+				Mode: 0o600,
+				Size: int64(len(content)),
+			}
+			aw.WriteHeader(hdr)
+			aw.Write(content)
+		}
+		return &buf
+	}
+
+	t.Run("MissingControlFile", func(t *testing.T) {
+		data := createArchive(map[string][]byte{"dummy.txt": {}})
+
+		p, err := ParsePackage(data)
+		assert.Nil(t, p)
+		assert.ErrorIs(t, err, ErrMissingControlFile)
+	})
+
+	t.Run("Compression", func(t *testing.T) {
+		t.Run("Unsupported", func(t *testing.T) {
+			data := createArchive(map[string][]byte{"control.tar.foo": {}})
+
+			p, err := ParsePackage(data)
+			assert.Nil(t, p)
+			assert.ErrorIs(t, err, ErrUnsupportedCompression)
+		})
+
+		var buf bytes.Buffer
+		tw := tar.NewWriter(&buf)
+		tw.WriteHeader(&tar.Header{
+			Name: "control",
+			Mode: 0o600,
+			Size: 50,
+		})
+		tw.Write([]byte("Package: gitea\nVersion: 1.0.0\nArchitecture: amd64\n"))
+		tw.Close()
+
+		t.Run("None", func(t *testing.T) {
+			data := createArchive(map[string][]byte{"control.tar": buf.Bytes()})
+
+			p, err := ParsePackage(data)
+			assert.NotNil(t, p)
+			assert.NoError(t, err)
+			assert.Equal(t, "gitea", p.Name)
+		})
+
+		t.Run("gz", func(t *testing.T) {
+			var zbuf bytes.Buffer
+			zw := gzip.NewWriter(&zbuf)
+			zw.Write(buf.Bytes())
+			zw.Close()
+
+			data := createArchive(map[string][]byte{"control.tar.gz": zbuf.Bytes()})
+
+			p, err := ParsePackage(data)
+			assert.NotNil(t, p)
+			assert.NoError(t, err)
+			assert.Equal(t, "gitea", p.Name)
+		})
+
+		t.Run("xz", func(t *testing.T) {
+			var xbuf bytes.Buffer
+			xw, _ := xz.NewWriter(&xbuf)
+			xw.Write(buf.Bytes())
+			xw.Close()
+
+			data := createArchive(map[string][]byte{"control.tar.xz": xbuf.Bytes()})
+
+			p, err := ParsePackage(data)
+			assert.NotNil(t, p)
+			assert.NoError(t, err)
+			assert.Equal(t, "gitea", p.Name)
+		})
+
+		t.Run("zst", func(t *testing.T) {
+			var zbuf bytes.Buffer
+			zw, _ := zstd.NewWriter(&zbuf)
+			zw.Write(buf.Bytes())
+			zw.Close()
+
+			data := createArchive(map[string][]byte{"control.tar.zst": zbuf.Bytes()})
+
+			p, err := ParsePackage(data)
+			assert.NotNil(t, p)
+			assert.NoError(t, err)
+			assert.Equal(t, "gitea", p.Name)
+		})
+	})
+}
+
+func TestParseControlFile(t *testing.T) {
+	buildContent := func(name, version, architecture string) *bytes.Buffer {
+		var buf bytes.Buffer
+		buf.WriteString("Package: " + name + "\nVersion: " + version + "\nArchitecture: " + architecture + "\nMaintainer: " + packageAuthor + " <kn4ck3r@gitea.io>\nHomepage: " + projectURL + "\nDepends: a,\n b\nDescription: Description\n with multiple\n lines.")
+		return &buf
+	}
+
+	t.Run("InvalidName", func(t *testing.T) {
+		for _, name := range []string{"", "-cd"} {
+			p, err := ParseControlFile(buildContent(name, packageVersion, packageArchitecture))
+			assert.Nil(t, p)
+			assert.ErrorIs(t, err, ErrInvalidName)
+		}
+	})
+
+	t.Run("InvalidVersion", func(t *testing.T) {
+		for _, version := range []string{"", "1-", ":1.0", "1_0"} {
+			p, err := ParseControlFile(buildContent(packageName, version, packageArchitecture))
+			assert.Nil(t, p)
+			assert.ErrorIs(t, err, ErrInvalidVersion)
+		}
+	})
+
+	t.Run("InvalidArchitecture", func(t *testing.T) {
+		p, err := ParseControlFile(buildContent(packageName, packageVersion, ""))
+		assert.Nil(t, p)
+		assert.ErrorIs(t, err, ErrInvalidArchitecture)
+	})
+
+	t.Run("Valid", func(t *testing.T) {
+		content := buildContent(packageName, packageVersion, packageArchitecture)
+		full := content.String()
+
+		p, err := ParseControlFile(content)
+		assert.NoError(t, err)
+		assert.NotNil(t, p)
+
+		assert.Equal(t, packageName, p.Name)
+		assert.Equal(t, packageVersion, p.Version)
+		assert.Equal(t, packageArchitecture, p.Architecture)
+		assert.Equal(t, description, p.Metadata.Description)
+		assert.Equal(t, projectURL, p.Metadata.ProjectURL)
+		assert.Equal(t, packageAuthor, p.Metadata.Maintainer)
+		assert.Equal(t, []string{"a", "b"}, p.Metadata.Dependencies)
+		assert.Equal(t, full, p.Control)
+	})
+}