More nca stuff

src/common/common_types.h

@@ -48,6 +48,9 @@ using PAddr = u64; ///< Represents a pointer in the ARM11 physical address space
 using u128 = std::array<std::uint64_t, 2>;
 static_assert(sizeof(u128) == 16, "u128 must be 128 bits wide");
 
+using u256 = std::array<std::uint64_t, 4>;
+static_assert(sizeof(u256) == 32, "u256 must be 256 bits wide");
+
 // An inheritable class to disallow the copy constructor and operator= functions
 class NonCopyable {
 protected:

src/core/loader/nca.cpp

@@ -17,11 +17,109 @@
 
 namespace Loader {
 
+enum NcaContentType {
+    NCT_PROGRAM = 0,
+    NCT_META = 1,
+    NCT_CONTROL = 2,
+    NCT_MANUAL = 3,
+    NCT_DATA = 4
+};
+
+struct NcaHeader {
+    u8 rsa_signature_1[0x100];
+    u8 rsa_signature_2[0x100];
+    u32 magic;
+    u8 is_system;
+    u8 content_type;
+    u8 crypto_type;
+    u8 key_index;
+    u64 size;
+    u64 title_id;
+    INSERT_PADDING_BYTES(0x4);
+    u32 sdk_version;
+    u8 crypto_type_2;
+    INSERT_PADDING_BYTES(0x9);
+    u128 rights_id;
+    u128 section_tables[0x4];
+    u256 hash_tables[0x4];
+    u128 key_area[0x4];
+    INSERT_PADDING_BYTES(0xC0);
+    INSERT_PADDING_BYTES(0x800);
+};
+static_assert(sizeof(NcaHeader) == 0xC00, "NcaHeader has incorrect size.");
+
+/**
+ * Adapted from hactool/aes.c, void aes_xts_decrypt(aes_ctx_t *ctx, void *dst,
+ *      const void *src, size_t l, size_t sector, size_t sector_size)
+ * and from various other functions in aes.c (get_tweak, aes_setiv, aes_decrypt)
+ *
+ * Copyright (c) 2018, SciresM
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ */
+template <size_t size>
+static std::array<u8, size> AesXtsDecrypt(std::array<u8, size> in, size_t sector_size) {
+    std::array<u8, 0x10> tweak;
+    ASSERT(size % sector_size == 0);
+
+    u8 sector = 0;
+
+    for (size_t i = 0; i < size; i += sector_size) {
+
+        // Get tweak
+        size_t sector_temp = sector++;
+        for (int i = 0xF; i >= 0; --i) {
+            tweak[i] = static_cast<u8>(sector_temp);
+            sector_temp >>= 8;
+        }
+
+        // Decrypt using lib or something
+    }
+}
+
+/**
+ * Adapted from hactool/nca.c, int nca_decrypt_header(nca_ctx_t *ctx)
+ *
+ * Copyright (c) 2018, SciresM
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ */
+static NcaHeader DecryptHeader(std::array<u8, 0xC00> enc_data) {
+    // Just in case its decrypted.
+    NcaHeader* header = reinterpret_cast<NcaHeader*>(enc_data.data());
+    if (header->magic == Common::MakeMagic('N', 'C', 'A', '2') ||
+        header->magic == Common::MakeMagic('N', 'C', 'A', '3'))
+        return *header;
+
+    std::array<u8, 0xC00> dec = AesXtsDecrypt(enc_data, 0x200);
+
+    header = reinterpret_cast<NcaHeader*>(dec.data());
+    return *header;
+}
+
+static bool IsValidNca(const NcaHeader& header) {
+    return header.magic == Common::MakeMagic('N', 'C', 'A', '2') ||
+           header.magic == Common::MakeMagic('N', 'C', 'A', '3');
+}
+
 AppLoader_NCA::AppLoader_NCA(FileUtil::IOFile&& file, std::string filepath)
     : AppLoader(std::move(file)), filepath(std::move(filepath)) {}
 
 FileType AppLoader_NCA::IdentifyType(FileUtil::IOFile& file, const std::string&) {
-    // Check for NCA header here -- that part might be enc. too :(
+
+    std::array<u8, 0xC00> header_enc_array{};
+    if (1 != file.ReadArray(header_enc_array.data(), 0xC00))
+        return FileType::Error;
+
+    NcaHeader header = DecryptHeader(header_enc_array);
+
+    if (IsValidNca(header) && header.content_type == NCT_PROGRAM)
+        return FileType::NCA;
+
     return FileType::Error;
 }
 

src/core/loader/nca.h

@@ -12,7 +12,7 @@
 
 namespace Loader {
 
-/// Loads an NRO file
+/// Loads an NCA file
 class AppLoader_NCA final : public AppLoader, Linker {
 public:
     AppLoader_NCA(FileUtil::IOFile&& file, std::string filepath);