/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file) 
 and all other portions of this file are Copyright (c) 2013-2016 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#include <fstream>
#include <iomanip>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include "CoreLinux.h"
#include "Platform/SystemInfo.h"
#include "Platform/TextReader.h"
#include "Volume/EncryptionModeXTS.h"
#include "Driver/Fuse/FuseService.h"
#include "Core/Unix/CoreServiceProxy.h"

namespace VeraCrypt
{
	CoreLinux::CoreLinux ()
	{
	}

	CoreLinux::~CoreLinux ()
	{
	}

	DevicePath CoreLinux::AttachFileToLoopDevice (const FilePath &filePath, bool readOnly) const
	{
		list <string> loopPaths;
		loopPaths.push_back ("/dev/loop");
		loopPaths.push_back ("/dev/loop/");
		loopPaths.push_back ("/dev/.static/dev/loop");
		
		// On Fedora 23,"losetup -f" must be called first to create a default loop device
		list <string> args;
		args.push_back ("-f");

		try
		{
			Process::Execute ("losetup", args);
		}
		catch (...) { }

		for (int devIndex = 0; devIndex < 256; devIndex++)
		{
			string loopDev;
			foreach (const string &loopPath, loopPaths)
			{
				loopDev = loopPath + StringConverter::ToSingle (devIndex);
				if (FilesystemPath (loopDev).IsBlockDevice())
					break;
			}

			if (loopDev.empty())
				continue;

			list <string> args;

			list <string>::iterator readOnlyArg;
			if (readOnly)
			{
				args.push_back ("-r");
				readOnlyArg = --args.end();
			}

			args.push_back ("--");
			args.push_back (loopDev);
			args.push_back (filePath);

			try
			{
				Process::Execute ("losetup", args);
				return loopDev;
			}
			catch (ExecutedProcessFailed&)
			{
				if (readOnly)
				{
					try
					{
						args.erase (readOnlyArg);
						Process::Execute ("losetup", args);
						return loopDev;
					}
					catch (ExecutedProcessFailed&) { }
				}
			}
		}

		throw LoopDeviceSetupFailed (SRC_POS, wstring (filePath));
	}

	void CoreLinux::DetachLoopDevice (const DevicePath &devicePath) const
	{
		list <string> args;
		args.push_back ("-d");
		args.push_back (devicePath);

		for (int t = 0; true; t++)
		{
			try
			{
				Process::Execute ("losetup", args);
				break;
			}
			catch (ExecutedProcessFailed&)
			{
				if (t > 5)
					throw;
				Thread::Sleep (200);
			}
		}
	}

	void CoreLinux::DismountNativeVolume (shared_ptr <VolumeInfo> mountedVolume) const
	{
		string devPath = mountedVolume->VirtualDevice;

		if (devPath.find ("/dev/mapper/veracrypt") != 0)
			throw NotApplicable (SRC_POS);

		size_t devCount = 0;
		while (FilesystemPath (devPath).IsBlockDevice())
		{
			list <string> dmsetupArgs;
			dmsetupArgs.push_back ("remove");
			dmsetupArgs.push_back (StringConverter::Split (devPath, "/").back());

			for (int t = 0; true; t++)
			{
				try
				{
					Process::Execute ("dmsetup", dmsetupArgs);
					break;
				}
				catch (...)
				{
					if (t > 20)
						throw;

					Thread::Sleep (100);
				}
			}

			for (int t = 0; FilesystemPath (devPath).IsBlockDevice() && t < 20; t++)
			{
				Thread::Sleep (100);
			}

			devPath = string (mountedVolume->VirtualDevice) + "_" + StringConverter::ToSingle (devCount++);
		}
	}

	HostDeviceList CoreLinux::GetHostDevices (bool pathListOnly) const
	{
		HostDeviceList devices;
		TextReader tr ("/proc/partitions");

		string line;
		while (tr.ReadLine (line))
		{
			vector <string> fields = StringConverter::Split (line);
			
			if (fields.size() != 4
				|| fields[3].find ("loop") == 0	// skip loop devices
				|| fields[3].find ("cloop") == 0
				|| fields[3].find ("ram") == 0	// skip RAM devices
				|| fields[3].find ("dm-") == 0	// skip device mapper devices
				|| fields[2] == "1"				// skip extended partitions
				)
				continue;

			try
			{
				StringConverter::ToUInt32 (fields[0]);
			}
			catch (...)
			{
				continue;
			}

			try
			{
				make_shared_auto (HostDevice, hostDevice);

				hostDevice->Path = string (fields[3].find ("/dev/") == string::npos ? "/dev/" : "") + fields[3];

				if (!pathListOnly)
				{
					hostDevice->Size = StringConverter::ToUInt64 (fields[2]) * 1024;
					hostDevice->MountPoint = GetDeviceMountPoint (hostDevice->Path);
					hostDevice->SystemNumber = 0;
				}

				try
				{
					StringConverter::GetTrailingNumber (fields[3]);
					if (devices.size() > 0)
					{
						HostDevice &prevDev = **--devices.end();
						if (string (hostDevice->Path).find (prevDev.Path) == 0)
						{
							prevDev.Partitions.push_back (hostDevice);
							continue;
						}
					}
				}
				catch (...) { }

				devices.push_back (hostDevice);
				continue;
			}
			catch (...)
			{
				continue;
			}
		}

		return devices;
	}

	MountedFilesystemList CoreLinux::GetMountedFilesystems (const DevicePath &devicePath, const DirectoryPath &mountPoint) const
	{
		MountedFilesystemList mountedFilesystems;
		DevicePath realDevicePath = devicePath;

		if (!devicePath.IsEmpty())
		{
			char *resolvedPath = realpath (string (devicePath).c_str(), NULL);
			if (resolvedPath)
			{
				realDevicePath = resolvedPath;
				free (resolvedPath);
			}
		}

		FILE *mtab = fopen ("/etc/mtab", "r");

		if (!mtab)
			mtab = fopen ("/proc/mounts", "r");

		throw_sys_sub_if (!mtab, "/proc/mounts");
		finally_do_arg (FILE *, mtab, { fclose (finally_arg); });

		static Mutex mutex;
		ScopeLock sl (mutex);

		struct mntent *entry;
		while ((entry = getmntent (mtab)) != nullptr)
		{
			make_shared_auto (MountedFilesystem, mf);

			if (entry->mnt_fsname)
				mf->Device = DevicePath (entry->mnt_fsname);
			else
				continue;

			if (entry->mnt_dir)
				mf->MountPoint = DirectoryPath (entry->mnt_dir);

			if (entry->mnt_type)
				mf->Type = entry->mnt_type;

			if ((devicePath.IsEmpty() || devicePath == mf->Device || realDevicePath == mf->Device) && (mountPoint.IsEmpty() || mountPoint == mf->MountPoint))
				mountedFilesystems.push_back (mf);
		}

		return mountedFilesystems;
	}

	void CoreLinux::MountFilesystem (const DevicePath &devicePath, const DirectoryPath &mountPoint, const string &filesystemType, bool readOnly, const string &systemMountOptions) const
	{
		bool fsMounted = false;

		try
		{
			if (!FilesystemSupportsUnixPermissions (devicePath))
			{
				stringstream userMountOptions;
				userMountOptions << "uid=" << GetRealUserId() << ",gid=" << GetRealGroupId() << ",umask=077" << (!systemMountOptions.empty() ? "," : "");

				CoreUnix::MountFilesystem (devicePath, mountPoint, filesystemType, readOnly, userMountOptions.str() + systemMountOptions);
				fsMounted = true;
			}
		}
		catch (...) { }

		if (!fsMounted)
			CoreUnix::MountFilesystem (devicePath, mountPoint, filesystemType, readOnly, systemMountOptions);
	}

	void CoreLinux::MountVolumeNative (shared_ptr <Volume> volume, MountOptions &options, const DirectoryPath &auxMountPoint) const
	{
		bool xts = (typeid (*volume->GetEncryptionMode()) == typeid (EncryptionModeXTS));

		if (options.NoKernelCrypto
			|| !xts
			|| volume->GetProtectionType() == VolumeProtection::HiddenVolumeReadOnly)
		{
			throw NotApplicable (SRC_POS);
		}

		if (!SystemInfo::IsVersionAtLeast (2, 6, xts ? 24 : 20))
			throw NotApplicable (SRC_POS);

		// Load device mapper kernel module
		list <string> execArgs;
		foreach (const string &dmModule, StringConverter::Split ("dm_mod dm-mod dm"))
		{
			execArgs.clear();
			execArgs.push_back (dmModule);

			try
			{
				Process::Execute ("modprobe", execArgs);
				break;
			}
			catch (...) { }
		}

		bool loopDevAttached = false;
		bool nativeDevCreated = false;
		bool filesystemMounted = false;

		// Attach volume to loopback device if required
		VolumePath volumePath = volume->GetPath();
		if (!volumePath.IsDevice())
		{
			volumePath = AttachFileToLoopDevice (volumePath, options.Protection == VolumeProtection::ReadOnly);
			loopDevAttached = true;
		}

		string nativeDevPath;

		try
		{
			// Create virtual device using device mapper
			size_t nativeDevCount = 0;
			size_t secondaryKeyOffset = volume->GetEncryptionMode()->GetKey().Size();
			size_t cipherCount = volume->GetEncryptionAlgorithm()->GetCiphers().size();

			foreach_reverse_ref (const Cipher &cipher, volume->GetEncryptionAlgorithm()->GetCiphers())
			{
				stringstream dmCreateArgs;
				dmCreateArgs << "0 " << volume->GetSize() / ENCRYPTION_DATA_UNIT_SIZE << " crypt ";

				// Mode
				dmCreateArgs << StringConverter::ToLower (StringConverter::ToSingle (cipher.GetName())) << (xts ? (SystemInfo::IsVersionAtLeast (2, 6, 33) ? "-xts-plain64 " : "-xts-plain ") : "-lrw-benbi ");

				size_t keyArgOffset = dmCreateArgs.str().size();
				dmCreateArgs << setw (cipher.GetKeySize() * (xts ? 4 : 2) + (xts ? 0 : 16 * 2)) << 0 << setw (0);

				// Sector and data unit offset
				uint64 startSector = volume->GetLayout()->GetDataOffset (volume->GetHostSize()) / ENCRYPTION_DATA_UNIT_SIZE;

				dmCreateArgs << ' ' << (xts ? startSector + volume->GetEncryptionMode()->GetSectorOffset() : 0) << ' ';
				if (nativeDevCount == 0)
					dmCreateArgs << string (volumePath) << ' ' << startSector;
				else
					dmCreateArgs << nativeDevPath << " 0";

				SecureBuffer dmCreateArgsBuf (dmCreateArgs.str().size());
				dmCreateArgsBuf.CopyFrom (ConstBufferPtr ((byte *) dmCreateArgs.str().c_str(), dmCreateArgs.str().size()));

				// Keys
				const SecureBuffer &cipherKey = cipher.GetKey();
				secondaryKeyOffset -= cipherKey.Size();
				ConstBufferPtr secondaryKey = volume->GetEncryptionMode()->GetKey().GetRange (xts ? secondaryKeyOffset : 0, xts ? cipherKey.Size() : 16);

				SecureBuffer hexStr (3);
				for (size_t i = 0; i < cipherKey.Size(); ++i)
				{
					sprintf ((char *) hexStr.Ptr(), "%02x", (int) cipherKey[i]);
					dmCreateArgsBuf.GetRange (keyArgOffset + i * 2, 2).CopyFrom (hexStr.GetRange (0, 2));

					sprintf ((char *) hexStr.Ptr(), "%02x", (int) secondaryKey[i]);
					dmCreateArgsBuf.GetRange (keyArgOffset + cipherKey.Size() * 2 + i * 2, 2).CopyFrom (hexStr.GetRange (0, 2));
				}

				stringstream nativeDevName;
				nativeDevName << "veracrypt" << options.SlotNumber;
				
				if (nativeDevCount != cipherCount - 1)
					nativeDevName << "_" << cipherCount - nativeDevCount - 2;
				
				nativeDevPath = "/dev/mapper/" + nativeDevName.str();

				execArgs.clear();
				execArgs.push_back ("create");
				execArgs.push_back (nativeDevName.str());

				Process::Execute ("dmsetup", execArgs, -1, nullptr, &dmCreateArgsBuf);
				
				// Wait for the device to be created
				for (int t = 0; true; t++)
				{
					try
					{
						FilesystemPath (nativeDevPath).GetType();
						break;
					}
					catch (...)
					{
						if (t > 20)
							throw;

						Thread::Sleep (100);
					}
				}

				nativeDevCreated = true;
				++nativeDevCount;
			}

			// Test whether the device mapper is able to read and decrypt the last sector
			SecureBuffer lastSectorBuf (volume->GetSectorSize());
			uint64 lastSectorOffset = volume->GetSize() - volume->GetSectorSize();

			File nativeDev;
			nativeDev.Open (nativeDevPath);
			nativeDev.ReadAt (lastSectorBuf, lastSectorOffset);

			SecureBuffer lastSectorBuf2 (volume->GetSectorSize());
			volume->ReadSectors (lastSectorBuf2, lastSectorOffset);

			if (memcmp (lastSectorBuf.Ptr(), lastSectorBuf2.Ptr(), volume->GetSectorSize()) != 0)
				throw KernelCryptoServiceTestFailed (SRC_POS);

			// Mount filesystem
			if (!options.NoFilesystem && options.MountPoint && !options.MountPoint->IsEmpty())
			{
				MountFilesystem (nativeDevPath, *options.MountPoint,
					StringConverter::ToSingle (options.FilesystemType),
					options.Protection == VolumeProtection::ReadOnly,
					StringConverter::ToSingle (options.FilesystemOptions));

				filesystemMounted = true;
			}

			FuseService::SendAuxDeviceInfo (auxMountPoint, nativeDevPath, volumePath);
		}
		catch (...)
		{
			try
			{
				if (filesystemMounted)
					DismountFilesystem (*options.MountPoint, true);
			}
			catch (...) { }

			try
			{
				if (nativeDevCreated)
				{
					make_shared_auto (VolumeInfo, vol);
					vol->VirtualDevice = nativeDevPath;
					DismountNativeVolume (vol);
				}
			}
			catch (...) { }

			try
			{
				if (loopDevAttached)
					DetachLoopDevice (volumePath);
			}
			catch (...) { }

			throw;
		}
	}

	auto_ptr <CoreBase> Core (new CoreServiceProxy <CoreLinux>);
	auto_ptr <CoreBase> CoreDirect (new CoreLinux);
}