func main() { flag.Parse() if flag.NArg() != 1 { fmt.Printf("Usage: xray FILE\n") os.Exit(1) } f := flag.Arg(0) fd, err := os.Open(f) if err != nil { errExit(err) } headerBytes := make([]byte, contentenc.HeaderLen) n, err := fd.ReadAt(headerBytes, 0) if err == io.EOF && n == 0 { fmt.Println("empty file") os.Exit(0) } else if err == io.EOF { fmt.Printf("incomplete file header: read %d bytes, want %d\n", n, contentenc.HeaderLen) os.Exit(1) } else if err != nil { errExit(err) } header, err := contentenc.ParseHeader(headerBytes) if err != nil { errExit(err) } prettyPrintHeader(header) var i int64 for i = 0; ; i++ { blockLen := int64(blockSize) off := contentenc.HeaderLen + i*blockSize iv := make([]byte, ivLen) _, err := fd.ReadAt(iv, off) if err == io.EOF { break } else if err != nil { errExit(err) } tag := make([]byte, cryptocore.AuthTagLen) _, err = fd.ReadAt(tag, off+blockSize-cryptocore.AuthTagLen) if err == io.EOF { fi, err2 := fd.Stat() if err2 != nil { errExit(err2) } _, err2 = fd.ReadAt(tag, fi.Size()-cryptocore.AuthTagLen) if err2 != nil { errExit(err2) } blockLen = (fi.Size() - contentenc.HeaderLen) % blockSize } else if err != nil { errExit(err) } fmt.Printf("Block %2d: IV: %s, Tag: %s, Offset: %5d Len: %d\n", i, hex.EncodeToString(iv), hex.EncodeToString(tag), off, blockLen) } }
// readFileID loads the file header from disk and extracts the file ID. // Returns io.EOF if the file is empty. func (f *file) readFileID() ([]byte, error) { buf := make([]byte, contentenc.HeaderLen) _, err := f.fd.ReadAt(buf, 0) if err != nil { return nil, err } h, err := contentenc.ParseHeader(buf) if err != nil { return nil, err } return h.ID, nil }