sysops
27d45f58e8
Sprint 1: Emails werden vor AES-256-GCM optional gzip-komprimiert (compress: true). Magic-Byte 0x01 als Prefix ermöglicht backward-kompatibles Load() für Legacy-Dateien. Neue DB-Tabelle storage_objects trackt Kompressions-Metadaten. Sprint 2: Attachments werden via SHA-256 dedupliziert — gleicher Anhang in N Mails wird nur einmal gespeichert. Neue Tabellen: attachments, email_attachments. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
57 lines
1.5 KiB
Go
57 lines
1.5 KiB
Go
package storage
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import (
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"bytes"
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"compress/gzip"
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"fmt"
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"io"
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)
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// Compression magic byte — prepended to compressed content before encryption.
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// RFC 2822 email headers always start with printable ASCII (>= 0x20),
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// so 0x01 is safe as a marker and will never appear in legacy uncompressed files.
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const (
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magicGzip = byte(0x01)
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)
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// compressGzip compresses data with gzip and prepends the magic byte.
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// Returns an error only on internal gzip failure (effectively never).
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func compressGzip(data []byte) ([]byte, error) {
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var buf bytes.Buffer
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buf.WriteByte(magicGzip)
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w, err := gzip.NewWriterLevel(&buf, gzip.BestCompression)
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if err != nil {
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return nil, fmt.Errorf("storage: gzip writer: %w", err)
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}
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if _, err := w.Write(data); err != nil {
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_ = w.Close()
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return nil, fmt.Errorf("storage: gzip write: %w", err)
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}
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if err := w.Close(); err != nil {
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return nil, fmt.Errorf("storage: gzip close: %w", err)
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}
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return buf.Bytes(), nil
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}
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// maybeDecompress inspects the first byte of data and decompresses if needed.
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// Legacy files (no magic byte, first byte is printable ASCII) are returned as-is.
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func maybeDecompress(data []byte) ([]byte, error) {
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if len(data) < 2 {
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return data, nil
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}
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if data[0] != magicGzip {
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// Legacy file: no compression — return as-is
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return data, nil
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}
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r, err := gzip.NewReader(bytes.NewReader(data[1:]))
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if err != nil {
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return nil, fmt.Errorf("storage: gzip reader: %w", err)
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}
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defer r.Close()
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out, err := io.ReadAll(r)
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if err != nil {
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return nil, fmt.Errorf("storage: gzip decompress: %w", err)
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}
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return out, nil
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}
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