Make netplay's "same game" check more robust

Instead of comparing the game ID, revision, disc number and name,
we can compare a hash of important parts of the disc including
all the aforementioned data but also additional data such as the
FST. The primary reason why I'm making this change is to let us
catch more desyncs before they happen, but this should also fix
https://bugs.dolphin-emu.org/issues/12115. As a bonus, the UI can
now distinguish the case where a client doesn't have the game at
all from the case where a client has the wrong version of the game.

Source/Core/UICommon/GameFile.cpp

@@ -5,6 +5,7 @@
 #include "UICommon/GameFile.h"
 
 #include <algorithm>
+#include <array>
 #include <cinttypes>
 #include <cstdio>
 #include <cstring>
@@ -13,11 +14,13 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <string_view>
 #include <tuple>
 #include <utility>
 #include <vector>
 
 #include <fmt/format.h>
+#include <mbedtls/sha1.h>
 #include <pugixml.hpp>
 
 #include "Common/ChunkFile.h"
@@ -532,7 +535,7 @@ std::vector<DiscIO::Language> GameFile::GetLanguages() const
   return languages;
 }
 
-std::string GameFile::GetUniqueIdentifier() const
+std::string GameFile::GetNetPlayName() const
 {
   std::vector<std::string> info;
   if (!GetGameID().empty())
@@ -566,6 +569,66 @@ std::string GameFile::GetUniqueIdentifier() const
   return name + " (" + ss.str() + ")";
 }
 
+std::array<u8, 20> GameFile::GetSyncHash() const
+{
+  std::array<u8, 20> hash{};
+
+  if (m_platform == DiscIO::Platform::ELFOrDOL)
+  {
+    std::string buffer;
+    if (File::ReadFileToString(m_file_path, buffer))
+      mbedtls_sha1_ret(reinterpret_cast<unsigned char*>(buffer.data()), buffer.size(), hash.data());
+  }
+  else
+  {
+    if (std::unique_ptr<DiscIO::Volume> volume = DiscIO::CreateVolume(m_file_path))
+      hash = volume->GetSyncHash();
+  }
+
+  return hash;
+}
+
+NetPlay::SyncIdentifier GameFile::GetSyncIdentifier() const
+{
+  const u64 dol_elf_size = m_platform == DiscIO::Platform::ELFOrDOL ? m_file_size : 0;
+  return NetPlay::SyncIdentifier{dol_elf_size,  m_game_id,       m_revision,
+                                 m_disc_number, m_is_datel_disc, GetSyncHash()};
+}
+
+NetPlay::SyncIdentifierComparison
+GameFile::CompareSyncIdentifier(const NetPlay::SyncIdentifier& sync_identifier) const
+{
+  const bool is_elf_or_dol = m_platform == DiscIO::Platform::ELFOrDOL;
+  if ((is_elf_or_dol ? m_file_size : 0) != sync_identifier.dol_elf_size)
+    return NetPlay::SyncIdentifierComparison::DifferentGame;
+
+  const auto trim = [](const std::string& str, size_t n) {
+    return std::string_view(str.data(), std::min(n, str.size()));
+  };
+
+  if (trim(m_game_id, 3) != trim(sync_identifier.game_id, 3))
+    return NetPlay::SyncIdentifierComparison::DifferentGame;
+
+  if (m_disc_number != sync_identifier.disc_number || m_is_datel_disc != sync_identifier.is_datel)
+    return NetPlay::SyncIdentifierComparison::DifferentGame;
+
+  const NetPlay::SyncIdentifierComparison mismatch_result =
+      is_elf_or_dol || m_is_datel_disc ? NetPlay::SyncIdentifierComparison::DifferentGame :
+                                         NetPlay::SyncIdentifierComparison::DifferentVersion;
+
+  if (m_game_id != sync_identifier.game_id)
+  {
+    const bool game_id_is_title_id = m_game_id.size() > 6 || sync_identifier.game_id.size() > 6;
+    return game_id_is_title_id ? NetPlay::SyncIdentifierComparison::DifferentGame : mismatch_result;
+  }
+
+  if (m_revision != sync_identifier.revision)
+    return mismatch_result;
+
+  return GetSyncHash() == sync_identifier.sync_hash ? NetPlay::SyncIdentifierComparison::SameGame :
+                                                      mismatch_result;
+}
+
 std::string GameFile::GetWiiFSPath() const
 {
   ASSERT(DiscIO::IsWii(m_platform));

Source/Core/UICommon/GameFile.h

@@ -4,11 +4,13 @@
 
 #pragma once
 
+#include <array>
 #include <map>
 #include <string>
 #include <vector>
 
 #include "Common/CommonTypes.h"
+#include "Core/SyncIdentifier.h"
 #include "DiscIO/Blob.h"
 #include "DiscIO/Enums.h"
 
@@ -80,7 +82,16 @@ public:
   u16 GetRevision() const { return m_revision; }
   // 0 is the first disc, 1 is the second disc
   u8 GetDiscNumber() const { return m_disc_number; }
-  std::string GetUniqueIdentifier() const;
+  std::string GetNetPlayName() const;
+
+  // This function is slow
+  std::array<u8, 20> GetSyncHash() const;
+  // This function is slow
+  NetPlay::SyncIdentifier GetSyncIdentifier() const;
+  // This function is slow if all of game_id, revision, disc_number, is_datel are identical
+  NetPlay::SyncIdentifierComparison
+  CompareSyncIdentifier(const NetPlay::SyncIdentifier& sync_identifier) const;
+
   std::string GetWiiFSPath() const;
   DiscIO::Region GetRegion() const { return m_region; }
   DiscIO::Country GetCountry() const { return m_country; }