// Copyright 2020 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 config provides basic infrastructure to set configuration settings
// for runsc. The configuration is set by flags to the command line. They can
// also propagate to a different process using the same flags.
package config

import (
	"fmt"
	"strconv"
	"strings"

	"gvisor.dev/gvisor/pkg/refs"
	"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)
	}
}

// MakeRefsLeakMode converts type from string.
func MakeRefsLeakMode(s string) (refs.LeakMode, error) {
	switch strings.ToLower(s) {
	case "disabled":
		return refs.NoLeakChecking, nil
	case "log-names":
		return refs.LeaksLogWarning, nil
	case "log-traces":
		return refs.LeaksLogTraces, nil
	default:
		return 0, fmt.Errorf("invalid refs leakmode %q", s)
	}
}

func refsLeakModeToString(mode refs.LeakMode) string {
	switch mode {
	// If not set, default it to disabled.
	case refs.UninitializedLeakChecking, refs.NoLeakChecking:
		return "disabled"
	case refs.LeaksLogWarning:
		return "log-names"
	case refs.LeaksLogTraces:
		return "log-traces"
	default:
		panic(fmt.Sprintf("Invalid leakmode: %d", mode))
	}
}

// QueueingDiscipline is used to specify the kind of Queueing Discipline to
// apply for a give FDBasedLink.
type QueueingDiscipline int

const (
	// QDiscNone disables any queueing for the underlying FD.
	QDiscNone QueueingDiscipline = iota

	// QDiscFIFO applies a simple fifo based queue to the underlying
	// FD.
	QDiscFIFO
)

// MakeQueueingDiscipline if possible the equivalent QueuingDiscipline for s
// else returns an error.
func MakeQueueingDiscipline(s string) (QueueingDiscipline, error) {
	switch s {
	case "none":
		return QDiscNone, nil
	case "fifo":
		return QDiscFIFO, nil
	default:
		return 0, fmt.Errorf("unsupported qdisc specified: %q", s)
	}
}

// String implements fmt.Stringer.
func (q QueueingDiscipline) String() string {
	switch q {
	case QDiscNone:
		return "none"
	case QDiscFIFO:
		return "fifo"
	default:
		panic(fmt.Sprintf("Invalid queueing discipline: %d", q))
	}
}

// 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

	// PanicLog is the path to log GO's runtime messages, if not empty.
	PanicLog 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

	// FSGoferHostUDS enables the gofer to mount a host UDS.
	FSGoferHostUDS 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

	// HardwareGSO indicates that hardware segmentation offload is enabled.
	HardwareGSO bool

	// SoftwareGSO indicates that software segmentation offload is enabled.
	SoftwareGSO bool

	// TXChecksumOffload indicates that TX Checksum Offload is enabled.
	TXChecksumOffload bool

	// RXChecksumOffload indicates that RX Checksum Offload is enabled.
	RXChecksumOffload bool

	// QDisc indicates the type of queuening discipline to use by default
	// for non-loopback interfaces.
	QDisc QueueingDiscipline

	// 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

	// 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

	// ReferenceLeakMode sets reference leak check mode
	ReferenceLeakMode refs.LeakMode

	// OverlayfsStaleRead instructs the sandbox to assume that the root mount
	// is on a Linux overlayfs mount, which does not necessarily preserve
	// coherence between read-only and subsequent writable file descriptors
	// representing the "same" file.
	OverlayfsStaleRead bool

	// CPUNumFromQuota sets CPU number count to available CPU quota, using
	// least integer value greater than or equal to quota.
	//
	// E.g. 0.2 CPU quota will result in 1, and 1.9 in 2.
	CPUNumFromQuota bool

	// Enables VFS2 (not plumbed through yet).
	VFS2 bool

	// Enables FUSE usage (not plumbed through yet).
	FUSE bool

	// 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

	// TestOnlyTestNameEnv should only be used in tests. It looks up for the
	// test name in the container environment variables and adds it to the debug
	// log file name. This is done to help identify the log with the test when
	// multiple tests are run in parallel, since there is no way to pass
	// parameters to the runtime from docker.
	TestOnlyTestNameEnv string
}

// 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,
		"--panic-log=" + c.PanicLog,
		"--debug-log-format=" + c.DebugLogFormat,
		"--file-access=" + c.FileAccess.String(),
		"--overlay=" + strconv.FormatBool(c.Overlay),
		"--fsgofer-host-uds=" + strconv.FormatBool(c.FSGoferHostUDS),
		"--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),
		"--ref-leak-mode=" + refsLeakModeToString(c.ReferenceLeakMode),
		"--gso=" + strconv.FormatBool(c.HardwareGSO),
		"--software-gso=" + strconv.FormatBool(c.SoftwareGSO),
		"--rx-checksum-offload=" + strconv.FormatBool(c.RXChecksumOffload),
		"--tx-checksum-offload=" + strconv.FormatBool(c.TXChecksumOffload),
		"--overlayfs-stale-read=" + strconv.FormatBool(c.OverlayfsStaleRead),
		"--qdisc=" + c.QDisc.String(),
		"--vfs2=" + strconv.FormatBool(c.VFS2),
		"--fuse=" + strconv.FormatBool(c.FUSE),
	}
	if c.CPUNumFromQuota {
		f = append(f, "--cpu-num-from-quota")
	}
	if c.VFS2 {
		f = append(f, "--vfs2=true")
	}
	if c.FUSE {
		f = append(f, "--fuse=true")
	}

	// Only include these if set since it is never to be used by users.
	if c.TestOnlyAllowRunAsCurrentUserWithoutChroot {
		f = append(f, "--TESTONLY-unsafe-nonroot=true")
	}
	if len(c.TestOnlyTestNameEnv) != 0 {
		f = append(f, "--TESTONLY-test-name-env="+c.TestOnlyTestNameEnv)
	}

	return f
}