// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package boot

import (
	"fmt"
	"strconv"
	"strings"

	"gvisor.dev/gvisor/pkg/sentry/watchdog"
)

// FileAccessType tells how the filesystem is accessed.
type FileAccessType int

const (
	// FileAccessShared sends IO requests to a Gofer process that validates the
	// requests and forwards them to the host.
	FileAccessShared FileAccessType = iota

	// FileAccessExclusive is the same as FileAccessShared, but enables
	// extra caching for improved performance. It should only be used if
	// the sandbox has exclusive access to the filesystem.
	FileAccessExclusive
)

// MakeFileAccessType converts type from string.
func MakeFileAccessType(s string) (FileAccessType, error) {
	switch s {
	case "shared":
		return FileAccessShared, nil
	case "exclusive":
		return FileAccessExclusive, nil
	default:
		return 0, fmt.Errorf("invalid file access type %q", s)
	}
}

func (f FileAccessType) String() string {
	switch f {
	case FileAccessShared:
		return "shared"
	case FileAccessExclusive:
		return "exclusive"
	default:
		return fmt.Sprintf("unknown(%d)", f)
	}
}

// NetworkType tells which network stack to use.
type NetworkType int

const (
	// NetworkSandbox uses internal network stack, isolated from the host.
	NetworkSandbox NetworkType = iota

	// NetworkHost redirects network related syscalls to the host network.
	NetworkHost

	// NetworkNone sets up just loopback using netstack.
	NetworkNone
)

// MakeNetworkType converts type from string.
func MakeNetworkType(s string) (NetworkType, error) {
	switch s {
	case "sandbox":
		return NetworkSandbox, nil
	case "host":
		return NetworkHost, nil
	case "none":
		return NetworkNone, nil
	default:
		return 0, fmt.Errorf("invalid network type %q", s)
	}
}

func (n NetworkType) String() string {
	switch n {
	case NetworkSandbox:
		return "sandbox"
	case NetworkHost:
		return "host"
	case NetworkNone:
		return "none"
	default:
		return fmt.Sprintf("unknown(%d)", n)
	}
}

// MakeWatchdogAction converts type from string.
func MakeWatchdogAction(s string) (watchdog.Action, error) {
	switch strings.ToLower(s) {
	case "log", "logwarning":
		return watchdog.LogWarning, nil
	case "panic":
		return watchdog.Panic, nil
	default:
		return 0, fmt.Errorf("invalid watchdog action %q", s)
	}
}

// Config holds configuration that is not part of the runtime spec.
type Config struct {
	// RootDir is the runtime root directory.
	RootDir string

	// Debug indicates that debug logging should be enabled.
	Debug bool

	// LogFilename is the filename to log to, if not empty.
	LogFilename string

	// LogFormat is the log format.
	LogFormat string

	// DebugLog is the path to log debug information to, if not empty.
	DebugLog string

	// DebugLogFormat is the log format for debug.
	DebugLogFormat string

	// FileAccess indicates how the filesystem is accessed.
	FileAccess FileAccessType

	// Overlay is whether to wrap the root filesystem in an overlay.
	Overlay bool

	// fsGoferHostUDSAllowed enables the gofer to mount a host UDS
	FSGoferHostUDSAllowed bool

	// Network indicates what type of network to use.
	Network NetworkType

	// EnableRaw indicates whether raw sockets should be enabled. Raw
	// sockets are disabled by stripping CAP_NET_RAW from the list of
	// capabilities.
	EnableRaw bool

	// GSO indicates that generic segmentation offload is enabled.
	GSO bool

	// LogPackets indicates that all network packets should be logged.
	LogPackets bool

	// Platform is the platform to run on.
	Platform string

	// Strace indicates that strace should be enabled.
	Strace bool

	// StraceSyscalls is the set of syscalls to trace.  If StraceEnable is
	// true and this list is empty, then all syscalls will be traced.
	StraceSyscalls []string

	// StraceLogSize is the max size of data blobs to display.
	StraceLogSize uint

	// DisableSeccomp indicates whether seccomp syscall filters should be
	// disabled. Pardon the double negation, but default to enabled is important.
	DisableSeccomp bool

	// WatchdogAction sets what action the watchdog takes when triggered.
	WatchdogAction watchdog.Action

	// PanicSignal registers signal handling that panics. Usually set to
	// SIGUSR2(12) to troubleshoot hangs. -1 disables it.
	PanicSignal int

	// ProfileEnable is set to prepare the sandbox to be profiled.
	ProfileEnable bool

	// RestoreFile is the path to the saved container image
	RestoreFile string

	// TestOnlyAllowRunAsCurrentUserWithoutChroot should only be used in
	// tests. It allows runsc to start the sandbox process as the current
	// user, and without chrooting the sandbox process. This can be
	// necessary in test environments that have limited capabilities.
	TestOnlyAllowRunAsCurrentUserWithoutChroot bool

	// NumNetworkChannels controls the number of AF_PACKET sockets that map
	// to the same underlying network device. This allows netstack to better
	// scale for high throughput use cases.
	NumNetworkChannels int

	// Rootless allows the sandbox to be started with a user that is not root.
	// Defense is depth measures are weaker with rootless. Specifically, the
	// sandbox and Gofer process run as root inside a user namespace with root
	// mapped to the caller's user.
	Rootless bool

	// AlsoLogToStderr allows to send log messages to stderr.
	AlsoLogToStderr bool
}

// ToFlags returns a slice of flags that correspond to the given Config.
func (c *Config) ToFlags() []string {
	f := []string{
		"--root=" + c.RootDir,
		"--debug=" + strconv.FormatBool(c.Debug),
		"--log=" + c.LogFilename,
		"--log-format=" + c.LogFormat,
		"--debug-log=" + c.DebugLog,
		"--debug-log-format=" + c.DebugLogFormat,
		"--file-access=" + c.FileAccess.String(),
		"--overlay=" + strconv.FormatBool(c.Overlay),
		"--network=" + c.Network.String(),
		"--log-packets=" + strconv.FormatBool(c.LogPackets),
		"--platform=" + c.Platform,
		"--strace=" + strconv.FormatBool(c.Strace),
		"--strace-syscalls=" + strings.Join(c.StraceSyscalls, ","),
		"--strace-log-size=" + strconv.Itoa(int(c.StraceLogSize)),
		"--watchdog-action=" + c.WatchdogAction.String(),
		"--panic-signal=" + strconv.Itoa(c.PanicSignal),
		"--profile=" + strconv.FormatBool(c.ProfileEnable),
		"--net-raw=" + strconv.FormatBool(c.EnableRaw),
		"--num-network-channels=" + strconv.Itoa(c.NumNetworkChannels),
		"--rootless=" + strconv.FormatBool(c.Rootless),
		"--alsologtostderr=" + strconv.FormatBool(c.AlsoLogToStderr),
	}
	if c.TestOnlyAllowRunAsCurrentUserWithoutChroot {
		// Only include if set since it is never to be used by users.
		f = append(f, "-TESTONLY-unsafe-nonroot=true")
	}
	return f
}