Merge pull request #10932 from JosJuice/nfs

DiscIO: Add support for the NFS format

1 files changed, 306 insertions, 0 deletions

diff --git a/Source/Core/DiscIO/NFSBlob.cpp b/Source/Core/DiscIO/NFSBlob.cpp
new file mode 100644
index 0000000000..da558361da
--- /dev/null
+++ b/Source/Core/DiscIO/NFSBlob.cpp
@@ -0,0 +1,306 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "DiscIO/NFSBlob.h"
+
+#include <algorithm>
+#include <array>
+#include <cstring>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+#include <fmt/format.h>
+
+#include "Common/Align.h"
+#include "Common/CommonTypes.h"
+#include "Common/Crypto/AES.h"
+#include "Common/IOFile.h"
+#include "Common/Logging/Log.h"
+#include "Common/StringUtil.h"
+#include "Common/Swap.h"
+
+namespace DiscIO
+{
+bool NFSFileReader::ReadKey(const std::string& path, const std::string& directory, Key* key_out)
+{
+  const std::string_view directory_without_trailing_slash =
+      std::string_view(directory).substr(0, directory.size() - 1);
+
+  std::string parent, parent_name, parent_extension;
+  SplitPath(directory_without_trailing_slash, &parent, &parent_name, &parent_extension);
+
+  if (parent_name + parent_extension != "content")
+  {
+    ERROR_LOG_FMT(DISCIO, "hif_000000.nfs is not in a directory named 'content': {}", path);
+    return false;
+  }
+
+  const std::string key_path = parent + "code/htk.bin";
+  File::IOFile key_file(key_path, "rb");
+  if (!key_file.ReadBytes(key_out->data(), key_out->size()))
+  {
+    ERROR_LOG_FMT(DISCIO, "Failed to read from {}", key_path);
+    return false;
+  }
+
+  return true;
+}
+
+std::vector<NFSLBARange> NFSFileReader::GetLBARanges(const NFSHeader& header)
+{
+  const size_t lba_range_count =
+      std::min<size_t>(Common::swap32(header.lba_range_count), header.lba_ranges.size());
+
+  std::vector<NFSLBARange> lba_ranges;
+  lba_ranges.reserve(lba_range_count);
+
+  for (size_t i = 0; i < lba_range_count; ++i)
+  {
+    const NFSLBARange& unswapped_lba_range = header.lba_ranges[i];
+    lba_ranges.push_back(NFSLBARange{Common::swap32(unswapped_lba_range.start_block),
+                                     Common::swap32(unswapped_lba_range.num_blocks)});
+  }
+
+  return lba_ranges;
+}
+
+std::vector<File::IOFile> NFSFileReader::OpenFiles(const std::string& directory,
+                                                   File::IOFile first_file, u64 expected_raw_size,
+                                                   u64* raw_size_out)
+{
+  const u64 file_count = Common::AlignUp(expected_raw_size, MAX_FILE_SIZE) / MAX_FILE_SIZE;
+
+  std::vector<File::IOFile> files;
+  files.reserve(file_count);
+
+  u64 raw_size = first_file.GetSize();
+  files.emplace_back(std::move(first_file));
+
+  for (u64 i = 1; i < file_count; ++i)
+  {
+    const std::string child_path = fmt::format("{}hif_{:06}.nfs", directory, i);
+    File::IOFile child(child_path, "rb");
+    if (!child)
+    {
+      ERROR_LOG_FMT(DISCIO, "Failed to open {}", child_path);
+      return {};
+    }
+
+    raw_size += child.GetSize();
+    files.emplace_back(std::move(child));
+  }
+
+  if (raw_size < expected_raw_size)
+  {
+    ERROR_LOG_FMT(
+        DISCIO,
+        "Expected sum of NFS file sizes for {} to be at least {} bytes, but it was {} bytes",
+        directory, expected_raw_size, raw_size);
+    return {};
+  }
+
+  return files;
+}
+
+u64 NFSFileReader::CalculateExpectedRawSize(const std::vector<NFSLBARange>& lba_ranges)
+{
+  u64 total_blocks = 0;
+  for (const NFSLBARange& range : lba_ranges)
+    total_blocks += range.num_blocks;
+
+  return sizeof(NFSHeader) + total_blocks * BLOCK_SIZE;
+}
+
+u64 NFSFileReader::CalculateExpectedDataSize(const std::vector<NFSLBARange>& lba_ranges)
+{
+  u32 greatest_block_index = 0;
+  for (const NFSLBARange& range : lba_ranges)
+    greatest_block_index = std::max(greatest_block_index, range.start_block + range.num_blocks);
+
+  return u64(greatest_block_index) * BLOCK_SIZE;
+}
+
+std::unique_ptr<NFSFileReader> NFSFileReader::Create(File::IOFile first_file,
+                                                     const std::string& path)
+{
+  std::string directory, filename, extension;
+  SplitPath(path, &directory, &filename, &extension);
+  if (filename + extension != "hif_000000.nfs")
+    return nullptr;
+
+  std::array<u8, 16> key;
+  if (!ReadKey(path, directory, &key))
+    return nullptr;
+
+  NFSHeader header;
+  if (!first_file.Seek(0, File::SeekOrigin::Begin) ||
+      !first_file.ReadArray(&header, 1) && header.magic != NFS_MAGIC)
+  {
+    return nullptr;
+  }
+
+  std::vector<NFSLBARange> lba_ranges = GetLBARanges(header);
+
+  const u64 expected_raw_size = CalculateExpectedRawSize(lba_ranges);
+
+  u64 raw_size;
+  std::vector<File::IOFile> files =
+      OpenFiles(directory, std::move(first_file), expected_raw_size, &raw_size);
+
+  if (files.empty())
+    return nullptr;
+
+  return std::unique_ptr<NFSFileReader>(
+      new NFSFileReader(std::move(lba_ranges), std::move(files), key, raw_size));
+}
+
+NFSFileReader::NFSFileReader(std::vector<NFSLBARange> lba_ranges, std::vector<File::IOFile> files,
+                             Key key, u64 raw_size)
+    : m_lba_ranges(std::move(lba_ranges)), m_files(std::move(files)),
+      m_aes_context(Common::AES::CreateContextDecrypt(key.data())), m_raw_size(raw_size)
+{
+  m_data_size = CalculateExpectedDataSize(m_lba_ranges);
+}
+
+u64 NFSFileReader::GetDataSize() const
+{
+  return m_data_size;
+}
+
+u64 NFSFileReader::GetRawSize() const
+{
+  return m_raw_size;
+}
+
+u64 NFSFileReader::ToPhysicalBlockIndex(u64 logical_block_index)
+{
+  u64 physical_blocks_so_far = 0;
+
+  for (const NFSLBARange& range : m_lba_ranges)
+  {
+    if (logical_block_index >= range.start_block &&
+        logical_block_index < range.start_block + range.num_blocks)
+    {
+      return physical_blocks_so_far + (logical_block_index - range.start_block);
+    }
+
+    physical_blocks_so_far += range.num_blocks;
+  }
+
+  return std::numeric_limits<u64>::max();
+}
+
+bool NFSFileReader::ReadEncryptedBlock(u64 physical_block_index)
+{
+  constexpr u64 BLOCKS_PER_FILE = MAX_FILE_SIZE / BLOCK_SIZE;
+
+  const u64 file_index = physical_block_index / BLOCKS_PER_FILE;
+  const u64 block_in_file = physical_block_index % BLOCKS_PER_FILE;
+
+  if (block_in_file == BLOCKS_PER_FILE - 1)
+  {
+    // Special case. Because of the 0x200 byte header at the very beginning,
+    // the last block of each file has its last 0x200 bytes stored in the next file.
+
+    constexpr size_t PART_1_SIZE = BLOCK_SIZE - sizeof(NFSHeader);
+    constexpr size_t PART_2_SIZE = sizeof(NFSHeader);
+
+    File::IOFile& file_1 = m_files[file_index];
+    File::IOFile& file_2 = m_files[file_index + 1];
+
+    if (!file_1.Seek(sizeof(NFSHeader) + block_in_file * BLOCK_SIZE, File::SeekOrigin::Begin) ||
+        !file_1.ReadBytes(m_current_block_encrypted.data(), PART_1_SIZE))
+    {
+      file_1.ClearError();
+      return false;
+    }
+
+    if (!file_2.Seek(0, File::SeekOrigin::Begin) ||
+        !file_2.ReadBytes(m_current_block_encrypted.data() + PART_1_SIZE, PART_2_SIZE))
+    {
+      file_2.ClearError();
+      return false;
+    }
+  }
+  else
+  {
+    // Normal case. The read is offset by 0x200 bytes, but it's all within one file.
+
+    File::IOFile& file = m_files[file_index];
+
+    if (!file.Seek(sizeof(NFSHeader) + block_in_file * BLOCK_SIZE, File::SeekOrigin::Begin) ||
+        !file.ReadBytes(m_current_block_encrypted.data(), BLOCK_SIZE))
+    {
+      file.ClearError();
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void NFSFileReader::DecryptBlock(u64 logical_block_index)
+{
+  std::array<u8, 16> iv{};
+  const u64 swapped_block_index = Common::swap64(logical_block_index);
+  std::memcpy(iv.data() + iv.size() - sizeof(swapped_block_index), &swapped_block_index,
+              sizeof(swapped_block_index));
+
+  m_aes_context->Crypt(iv.data(), m_current_block_encrypted.data(),
+                       m_current_block_decrypted.data(), BLOCK_SIZE);
+}
+
+bool NFSFileReader::ReadAndDecryptBlock(u64 logical_block_index)
+{
+  const u64 physical_block_index = ToPhysicalBlockIndex(logical_block_index);
+
+  if (physical_block_index == std::numeric_limits<u64>::max())
+  {
+    // The block isn't physically present. Treat its contents as all zeroes.
+    m_current_block_decrypted.fill(0);
+  }
+  else
+  {
+    if (!ReadEncryptedBlock(physical_block_index))
+      return false;
+
+    DecryptBlock(logical_block_index);
+  }
+
+  // Small hack: Set 0x61 of the header to 1 so that VolumeWii realizes that the disc is unencrypted
+  if (logical_block_index == 0)
+    m_current_block_decrypted[0x61] = 1;
+
+  return true;
+}
+
+bool NFSFileReader::Read(u64 offset, u64 nbytes, u8* out_ptr)
+{
+  while (nbytes != 0)
+  {
+    const u64 logical_block_index = offset / BLOCK_SIZE;
+    const u64 offset_in_block = offset % BLOCK_SIZE;
+
+    if (logical_block_index != m_current_logical_block_index)
+    {
+      if (!ReadAndDecryptBlock(logical_block_index))
+        return false;
+
+      m_current_logical_block_index = logical_block_index;
+    }
+
+    const u64 bytes_to_copy = std::min(nbytes, BLOCK_SIZE - offset_in_block);
+    std::memcpy(out_ptr, m_current_block_decrypted.data() + offset_in_block, bytes_to_copy);
+
+    offset += bytes_to_copy;
+    nbytes -= bytes_to_copy;
+    out_ptr += bytes_to_copy;
+  }
+
+  return true;
+}
+
+}  // namespace DiscIO