IsNETAssembly checks if a PE file is a .NET assembly by looking for a non-zero CLR Runtime Header data directory entry.
(path string)
| 12 | // IsNETAssembly checks if a PE file is a .NET assembly by looking for a |
| 13 | // non-zero CLR Runtime Header data directory entry. |
| 14 | func IsNETAssembly(path string) (bool, error) { |
| 15 | f, err := os.Open(path) |
| 16 | if err != nil { |
| 17 | return false, err |
| 18 | } |
| 19 | defer f.Close() |
| 20 | |
| 21 | buf := make([]byte, 512) |
| 22 | n, err := f.Read(buf) |
| 23 | if err != nil { |
| 24 | return false, fmt.Errorf("read PE header: %w", err) |
| 25 | } |
| 26 | buf = buf[:n] |
| 27 | |
| 28 | if n < 2 || buf[0] != 'M' || buf[1] != 'Z' { |
| 29 | return false, nil |
| 30 | } |
| 31 | if n < 0x3C+4 { |
| 32 | return false, nil |
| 33 | } |
| 34 | peOffset := int(binary.LittleEndian.Uint32(buf[0x3C:])) |
| 35 | |
| 36 | if peOffset+4 > n { |
| 37 | return false, nil |
| 38 | } |
| 39 | if buf[peOffset] != 'P' || buf[peOffset+1] != 'E' || buf[peOffset+2] != 0 || buf[peOffset+3] != 0 { |
| 40 | return false, nil |
| 41 | } |
| 42 | |
| 43 | optHeaderOffset := peOffset + 4 + 20 |
| 44 | if optHeaderOffset+2 > n { |
| 45 | return false, nil |
| 46 | } |
| 47 | magic := binary.LittleEndian.Uint16(buf[optHeaderOffset:]) |
| 48 | |
| 49 | var dataDirOffset int |
| 50 | switch magic { |
| 51 | case 0x10b: // PE32 |
| 52 | dataDirOffset = optHeaderOffset + 96 |
| 53 | case 0x20b: // PE32+ |
| 54 | dataDirOffset = optHeaderOffset + 112 |
| 55 | default: |
| 56 | return false, nil |
| 57 | } |
| 58 | |
| 59 | clrEntryOffset := dataDirOffset + 14*8 |
| 60 | if clrEntryOffset+8 > n { |
| 61 | return false, nil |
| 62 | } |
| 63 | |
| 64 | rva := binary.LittleEndian.Uint32(buf[clrEntryOffset:]) |
| 65 | size := binary.LittleEndian.Uint32(buf[clrEntryOffset+4:]) |
| 66 | |
| 67 | return rva != 0 && size != 0, nil |
| 68 | } |
| 69 | |
| 70 | var microsoftTokens = map[string]bool{ |
| 71 | "b77a5c561934e089": true, // ECMA key (System.*, mscorlib) |