1 files changed, 202 insertions, 0 deletions
diff --git a/internal/slackware_com/mirror.go b/internal/slackware_com/mirror.go
new file mode 100644
index 0000000..f3bb4a8
--- /dev/null
+++ b/internal/slackware_com/mirror.go
@@ -0,0 +1,202 @@
+package slackware_com
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"hash"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"path"
+	"strings"
+)
+
+type Mirror struct {
+	client *http.Client
+	url    *url.URL
+
+	ChangeLog *ChangeLog
+	Checksums *Checksums
+}
+
+func OpenMirror(mirrorURL *url.URL) (*Mirror, error) {
+	var zeroDialer net.Dialer
+	transport := http.DefaultTransport.(*http.Transport).Clone()
+	transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+		return zeroDialer.DialContext(ctx, "tcp4", addr)
+	}
+	http.DefaultClient.Transport = transport
+
+	mirror := Mirror{
+		client: http.DefaultClient,
+		url:    mirrorURL,
+	}
+
+	err := mirror.Sync()
+	if err != nil {
+		return nil, err
+	}
+
+	return &mirror, nil
+}
+
+func signaturePath(filePath string) string {
+	return fmt.Sprintf("%s.asc", filePath)
+}
+
+func isSignature(filePath string) bool {
+	return strings.HasSuffix(filePath, ".asc")
+}
+
+func (m *Mirror) hasSignature(filePath string) bool {
+	if isSignature(filePath) {
+		return false
+	}
+	if path.Base(filePath) == ChecksumsMD5 {
+		return true
+	}
+	return m.Checksums.HasFilePath(signaturePath(filePath))
+}
+
+func (m *Mirror) DownloadAndVerify(wr io.Writer, filePath string) error {
+	fileUrl := m.url.JoinPath(filePath).String()
+	resp, err := m.client.Get(fileUrl)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("bad HTTP response: %s", http.StatusText(resp.StatusCode))
+	}
+
+	var r io.Reader = resp.Body
+	defer resp.Body.Close()
+
+	var hash *hash.Hash
+	if filePath != ChecksumsMD5 && filePath != signaturePath(ChecksumsMD5) {
+		h := m.Checksums.Hash()
+		r = io.TeeReader(r, h)
+
+		hash = &h
+	}
+
+	var signatureVerifier *GnuPGVerifier
+	if m.hasSignature(filePath) {
+		var signature bytes.Buffer
+		err := m.DownloadAndVerify(&signature, signaturePath(filePath))
+		if err != nil {
+			return err
+		}
+
+		signatureVerifier = RunSignatureVerifier(signature.String())
+		r = io.TeeReader(r, signatureVerifier)
+	}
+
+	_, err = io.Copy(wr, r)
+	if err != nil {
+		return err
+	}
+
+	if hash != nil {
+		ok, err := m.Checksums.Verify(filePath, (*hash).Sum(nil))
+		if err != nil {
+			return err
+		}
+		if !ok {
+			return fmt.Errorf("MD5 verification failed")
+		}
+	}
+
+	if signatureVerifier != nil {
+		ok, _ := signatureVerifier.IsValid()
+		if !ok {
+			return fmt.Errorf("signature verification failed")
+		}
+	}
+
+	return nil
+}
+
+func (m *Mirror) downloadChangeLog() error {
+	var buf bytes.Buffer
+	err := m.DownloadAndVerify(&buf, ChangeLogTxt)
+	if err != nil {
+		return fmt.Errorf("downloading %s: %w", ChangeLogTxt, err)
+	}
+
+	var changeLog ChangeLog
+	err = changeLog.UnmarshalText(buf.Bytes())
+	if err != nil {
+		return fmt.Errorf("%s: %w", ChangeLogTxt, err)
+	}
+	m.ChangeLog = &changeLog
+
+	return nil
+}
+
+func (m *Mirror) downloadChecksums() error {
+	var buf bytes.Buffer
+	err := m.DownloadAndVerify(&buf, ChecksumsMD5)
+	if err != nil {
+		return fmt.Errorf("downloading %s: %w", ChecksumsMD5, err)
+	}
+
+	var checksums Checksums
+	err = checksums.UnmarshalText(buf.Bytes())
+	if err != nil {
+		return fmt.Errorf("%s: %w", ChecksumsMD5, err)
+	}
+	m.Checksums = &checksums
+
+	return nil
+}
+
+// FindPackage returns the file path for the most appropriate package.
+func (m *Mirror) FindPackage(pattern PackageNamePattern) (string, bool) {
+	found := ""
+	priority := 0
+
+	pathPriority := 0
+	for _, file := range m.Checksums.Files() {
+		if !IsPackage(file) {
+			continue
+		}
+		file = path.Clean(file)
+
+		if strings.HasPrefix(file, "patches/packages") {
+			pathPriority = 5
+		} else if strings.HasPrefix(file, "slackware") {
+			pathPriority = 4
+		} else if strings.HasPrefix(file, "extra") {
+			pathPriority = 3
+		} else if strings.HasPrefix(file, "testing/packages") {
+			pathPriority = 2
+		} else if strings.HasPrefix(file, "pasture") {
+			pathPriority = 1
+		} else {
+			continue
+		}
+
+		pkg, _ := NewPackageNameFromPath(file)
+		if pattern.IsMatch(pkg) && pathPriority > priority {
+			found = file
+			priority = pathPriority
+		}
+	}
+
+	return found, found != ""
+}
+
+func (m *Mirror) Sync() error {
+	err := m.downloadChecksums()
+	if err != nil {
+		return err
+	}
+	err = m.downloadChangeLog()
+	if err != nil {
+		return err
+	}
+	return nil
+}