cfg.go

/*
Copyright 2015-2021 Gravitational, Inc.

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 service

import (
	"crypto/x509"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"go.mongodb.org/mongo-driver/mongo/readpref"
	"go.mongodb.org/mongo-driver/x/mongo/driver/connstring"
	"golang.org/x/crypto/ssh"
	"golang.org/x/net/http/httpguts"
	"k8s.io/apimachinery/pkg/util/validation"

	"github.com/gravitational/teleport/api/types"
	apiutils "github.com/gravitational/teleport/api/utils"
	"github.com/gravitational/teleport/lib/auth"
	"github.com/gravitational/teleport/lib/auth/keystore"
	"github.com/gravitational/teleport/lib/backend"
	"github.com/gravitational/teleport/lib/backend/lite"
	"github.com/gravitational/teleport/lib/backend/memory"
	"github.com/gravitational/teleport/lib/bpf"
	"github.com/gravitational/teleport/lib/defaults"
	"github.com/gravitational/teleport/lib/events"
	"github.com/gravitational/teleport/lib/kube/proxy"
	"github.com/gravitational/teleport/lib/limiter"
	"github.com/gravitational/teleport/lib/pam"
	"github.com/gravitational/teleport/lib/plugin"
	restricted "github.com/gravitational/teleport/lib/restrictedsession"
	"github.com/gravitational/teleport/lib/services"
	"github.com/gravitational/teleport/lib/srv/app/common"
	"github.com/gravitational/teleport/lib/sshca"
	"github.com/gravitational/teleport/lib/tlsca"
	"github.com/gravitational/teleport/lib/utils"

	"github.com/ghodss/yaml"
	"github.com/gravitational/trace"
	"github.com/jonboulle/clockwork"
)

// Rate describes a rate ratio, i.e. the number of "events" that happen over
// some unit time period
type Rate struct {
	Amount int
	Time   time.Duration
}

// Config structure is used to initialize _all_ services Teleport can run.
// Some settings are global (like DataDir) while others are grouped into
// sections, like AuthConfig
type Config struct {
	// Teleport configuration version.
	Version string
	// DataDir provides directory where teleport stores it's permanent state
	// (in case of auth server backed by BoltDB) or local state, e.g. keys
	DataDir string

	// Hostname is a node host name
	Hostname string

	// Token is used to register this Teleport instance with the auth server
	Token string

	// JoinMethod is the method the instance will use to join the auth server
	JoinMethod JoinMethod

	// AuthServers is a list of auth servers, proxies and peer auth servers to
	// connect to. Yes, this is not just auth servers, the field name is
	// misleading.
	AuthServers []utils.NetAddr

	// Identities is an optional list of pre-generated key pairs
	// for teleport roles, this is helpful when server is preconfigured
	Identities []*auth.Identity

	// AdvertiseIP is used to "publish" an alternative IP address or hostname this node
	// can be reached on, if running behind NAT
	AdvertiseIP string

	// CachePolicy sets caching policy for nodes and proxies
	// in case if they lose connection to auth servers
	CachePolicy CachePolicy

	// Auth service configuration. Manages cluster state and configuration.
	Auth AuthConfig

	// Proxy service configuration. Manages incoming and outbound
	// connections to the cluster.
	Proxy ProxyConfig

	// SSH service configuration. Manages SSH servers running within the cluster.
	SSH SSHConfig

	// App service configuration. Manages applications running within the cluster.
	Apps AppsConfig

	// Databases defines database proxy service configuration.
	Databases DatabasesConfig

	// Metrics defines the metrics service configuration.
	Metrics MetricsConfig

	// WindowsDesktop defines the Windows desktop service configuration.
	WindowsDesktop WindowsDesktopConfig

	// Keygen points to a key generator implementation
	Keygen sshca.Authority

	// KeyStore configuration. Handles CA private keys which may be held in a HSM.
	KeyStore keystore.Config

	// HostUUID is a unique UUID of this host (it will be known via this UUID within
	// a teleport cluster). It's automatically generated on 1st start
	HostUUID string

	// Console writer to speak to a user
	Console io.Writer

	// ReverseTunnels is a list of reverse tunnels to create on the
	// first cluster start
	ReverseTunnels []types.ReverseTunnel

	// OIDCConnectors is a list of trusted OpenID Connect identity providers
	OIDCConnectors []types.OIDCConnector

	// PidFile is a full path of the PID file for teleport daemon
	PIDFile string

	// Trust is a service that manages users and credentials
	Trust services.Trust

	// Presence service is a discovery and hearbeat tracker
	Presence services.Presence

	// Events is events service
	Events types.Events

	// Provisioner is a service that keeps track of provisioning tokens
	Provisioner services.Provisioner

	// Trust is a service that manages users and credentials
	Identity services.Identity

	// Access is a service that controls access
	Access services.Access

	// ClusterConfiguration is a service that provides cluster configuration
	ClusterConfiguration services.ClusterConfiguration

	// CipherSuites is a list of TLS ciphersuites that Teleport supports. If
	// omitted, a Teleport selected list of defaults will be used.
	CipherSuites []uint16

	// Ciphers is a list of SSH ciphers that the server supports. If omitted,
	// the defaults will be used.
	Ciphers []string

	// KEXAlgorithms is a list of SSH key exchange (KEX) algorithms that the
	// server supports. If omitted, the defaults will be used.
	KEXAlgorithms []string

	// MACAlgorithms is a list of SSH message authentication codes (MAC) that
	// the server supports. If omitted the defaults will be used.
	MACAlgorithms []string

	// CASignatureAlgorithm is an SSH Certificate Authority (CA) signature
	// algorithm that the server uses for signing user and host certificates.
	// If omitted, the default will be used.
	CASignatureAlgorithm *string

	// DiagnosticAddr is an address for diagnostic and healthz endpoint service
	DiagnosticAddr utils.NetAddr

	// Debug sets debugging mode, results in diagnostic address
	// endpoint extended with additional /debug handlers
	Debug bool

	// UploadEventsC is a channel for upload events
	// used in tests
	UploadEventsC chan events.UploadEvent `json:"-"`

	// FileDescriptors is an optional list of file descriptors for the process
	// to inherit and use for listeners, used for in-process updates.
	FileDescriptors []FileDescriptor

	// PollingPeriod is set to override default internal polling periods
	// of sync agents, used to speed up integration tests.
	PollingPeriod time.Duration

	// ClientTimeout is set to override default client timeouts
	// used by internal clients, used to speed up integration tests.
	ClientTimeout time.Duration

	// ShutdownTimeout is set to override default shutdown timeout.
	ShutdownTimeout time.Duration

	// CAPins are the SKPI hashes of the CAs used to verify the Auth Server.
	CAPins []string

	// Clock is used to control time in tests.
	Clock clockwork.Clock

	// FIPS means FedRAMP/FIPS 140-2 compliant configuration was requested.
	FIPS bool

	// BPFConfig holds configuration for the BPF service.
	BPFConfig *bpf.Config

	// Kube is a Kubernetes API gateway using Teleport client identities.
	Kube KubeConfig

	// Log optionally specifies the logger
	Log utils.Logger

	// PluginRegistry allows adding enterprise logic to Teleport services
	PluginRegistry plugin.Registry

	// RotationConnectionInterval is the interval between connection
	// attempts as used by the rotation state service
	RotationConnectionInterval time.Duration

	// RestartThreshold describes the number of connection failures per
	// unit time that the node can sustain before restarting itself, as
	// measured by the rotation state service.
	RestartThreshold Rate

	// MaxRetryPeriod is the maximum period between reconnection attempts to auth
	MaxRetryPeriod time.Duration

	// ConnectFailureC is a channel to notify of failures to connect to auth (used in tests).
	ConnectFailureC chan time.Duration
}

// ApplyToken assigns a given token to all internal services but only if token
// is not an empty string.
//
// returns:
// true, nil if the token has been modified
// false, nil if the token has not been modified
// false, err if there was an error
func (cfg *Config) ApplyToken(token string) (bool, error) {
	if token != "" {
		var err error
		cfg.Token, err = utils.ReadToken(token)
		if err != nil {
			return false, trace.Wrap(err)
		}
		return true, nil
	}
	return false, nil
}

// RoleConfig is a config for particular Teleport role
func (cfg *Config) RoleConfig() RoleConfig {
	return RoleConfig{
		DataDir:     cfg.DataDir,
		HostUUID:    cfg.HostUUID,
		HostName:    cfg.Hostname,
		AuthServers: cfg.AuthServers,
		Auth:        cfg.Auth,
		Console:     cfg.Console,
	}
}

// DebugDumpToYAML is useful for debugging: it dumps the Config structure into
// a string
func (cfg *Config) DebugDumpToYAML() string {
	shallow := *cfg
	// do not copy sensitive data to stdout
	shallow.Identities = nil
	shallow.Auth.Authorities = nil
	out, err := yaml.Marshal(shallow)
	if err != nil {
		return err.Error()
	}
	return string(out)
}

// CachePolicy sets caching policy for proxies and nodes
type CachePolicy struct {
	// Type sets the cache type
	Type string
	// Enabled enables or disables caching
	Enabled bool
}

// CheckAndSetDefaults checks and sets default values
func (c *CachePolicy) CheckAndSetDefaults() error {
	switch c.Type {
	case "", lite.GetName():
		c.Type = lite.GetName()
	case memory.GetName():
	default:
		return trace.BadParameter("unsupported cache type %q, supported values are %q and %q",
			c.Type, lite.GetName(), memory.GetName())
	}
	return nil
}

// String returns human-friendly representation of the policy
func (c CachePolicy) String() string {
	if !c.Enabled {
		return "no cache policy"
	}
	return fmt.Sprintf("%v cache will store frequently accessed items", c.Type)
}

// ProxyConfig specifies configuration for proxy service
type ProxyConfig struct {
	// Enabled turns proxy role on or off for this process
	Enabled bool

	// DisableTLS is enabled if we don't want self-signed certs
	DisableTLS bool

	// DisableWebInterface allows turning off serving the Web UI interface
	DisableWebInterface bool

	// DisableWebService turns off serving web service completely, including web UI
	DisableWebService bool

	// DisableReverseTunnel disables reverse tunnel on the proxy
	DisableReverseTunnel bool

	// DisableDatabaseProxy disables database access proxy listener
	DisableDatabaseProxy bool

	// ReverseTunnelListenAddr is address where reverse tunnel dialers connect to
	ReverseTunnelListenAddr utils.NetAddr

	// EnableProxyProtocol enables proxy protocol support
	EnableProxyProtocol bool

	// WebAddr is address for web portal of the proxy
	WebAddr utils.NetAddr

	// SSHAddr is address of ssh proxy
	SSHAddr utils.NetAddr

	// MySQLAddr is address of MySQL proxy.
	MySQLAddr utils.NetAddr

	// PostgresAddr is address of Postgres proxy.
	PostgresAddr utils.NetAddr

	// MongoAddr is address of Mongo proxy.
	MongoAddr utils.NetAddr

	Limiter limiter.Config

	// PublicAddrs is a list of the public addresses the proxy advertises
	// for the HTTP endpoint. The hosts in in PublicAddr are included in the
	// list of host principals on the TLS and SSH certificate.
	PublicAddrs []utils.NetAddr

	// SSHPublicAddrs is a list of the public addresses the proxy advertises
	// for the SSH endpoint. The hosts in in PublicAddr are included in the
	// list of host principals on the TLS and SSH certificate.
	SSHPublicAddrs []utils.NetAddr

	// TunnelPublicAddrs is a list of the public addresses the proxy advertises
	// for the tunnel endpoint. The hosts in PublicAddr are included in the
	// list of host principals on the TLS and SSH certificate.
	TunnelPublicAddrs []utils.NetAddr

	// PostgresPublicAddrs is a list of the public addresses the proxy
	// advertises for Postgres clients.
	PostgresPublicAddrs []utils.NetAddr

	// MySQLPublicAddrs is a list of the public addresses the proxy
	// advertises for MySQL clients.
	MySQLPublicAddrs []utils.NetAddr

	// MongoPublicAddrs is a list of the public addresses the proxy
	// advertises for Mongo clients.
	MongoPublicAddrs []utils.NetAddr

	// Kube specifies kubernetes proxy configuration
	Kube KubeProxyConfig

	// KeyPairs are the key and certificate pairs that the proxy will load.
	KeyPairs []KeyPairPath

	// ACME is ACME protocol support config
	ACME ACME

	// DisableALPNSNIListener allows turning off the ALPN Proxy listener. Used in tests.
	DisableALPNSNIListener bool
}

// ACME configures ACME automatic certificate renewal
type ACME struct {
	// Enabled enables or disables ACME support
	Enabled bool
	// Email receives notifications from ACME server
	Email string
	// URI is ACME server URI
	URI string
}

// KeyPairPath are paths to a key and certificate file.
type KeyPairPath struct {
	// PrivateKey is the path to a PEM encoded private key.
	PrivateKey string
	// Certificate is the path to a PEM encoded certificate.
	Certificate string
}

// KubeAddr returns the address for the Kubernetes endpoint on this proxy that
// can be reached by clients.
func (c ProxyConfig) KubeAddr() (string, error) {
	if !c.Kube.Enabled {
		return "", trace.NotFound("kubernetes support not enabled on this proxy")
	}
	if len(c.Kube.PublicAddrs) > 0 {
		return fmt.Sprintf("https://%s", c.Kube.PublicAddrs[0].Addr), nil
	}
	host := "<proxyhost>"
	// Try to guess the hostname from the HTTP public_addr.
	if len(c.PublicAddrs) > 0 {
		host = c.PublicAddrs[0].Host()
	}
	u := url.URL{
		Scheme: "https",
		Host:   net.JoinHostPort(host, strconv.Itoa(c.Kube.ListenAddr.Port(defaults.KubeListenPort))),
	}
	return u.String(), nil
}

// KubeProxyConfig specifies configuration for proxy service
type KubeProxyConfig struct {
	// Enabled turns kubernetes proxy role on or off for this process
	Enabled bool

	// ListenAddr is the address to listen on for incoming kubernetes requests.
	ListenAddr utils.NetAddr

	// ClusterOverride causes all traffic to go to a specific remote
	// cluster, used only in tests
	ClusterOverride string

	// PublicAddrs is a list of the public addresses the Teleport Kube proxy can be accessed by,
	// it also affects the host principals and routing logic
	PublicAddrs []utils.NetAddr

	// KubeconfigPath is a path to kubeconfig
	KubeconfigPath string

	// LegacyKubeProxy specifies that this proxy was configured using the
	// legacy kubernetes section.
	LegacyKubeProxy bool
}

// AuthConfig is a configuration of the auth server
type AuthConfig struct {
	// Enabled turns auth role on or off for this process
	Enabled bool

	// EnableProxyProtocol enables proxy protocol support
	EnableProxyProtocol bool

	// SSHAddr is the listening address of SSH tunnel to HTTP service
	SSHAddr utils.NetAddr

	// Authorities is a set of trusted certificate authorities
	// that will be added by this auth server on the first start
	Authorities []types.CertAuthority

	// Resources is a set of previously backed up resources
	// used to bootstrap backend state on the first start.
	Resources []types.Resource

	// Roles is a set of roles to pre-provision for this cluster
	Roles []types.Role

	// ClusterName is a name that identifies this authority and all
	// host nodes in the cluster that will share this authority domain name
	// as a base name, e.g. if authority domain name is example.com,
	// all nodes in the cluster will have UUIDs in the form: <uuid>.example.com
	ClusterName types.ClusterName

	// StaticTokens are pre-defined host provisioning tokens supplied via config file for
	// environments where paranoid security is not needed
	StaticTokens types.StaticTokens

	// StorageConfig contains configuration settings for the storage backend.
	StorageConfig backend.Config

	Limiter limiter.Config

	// NoAudit, when set to true, disables session recording and event audit
	NoAudit bool

	// Preference defines the authentication preference (type and second factor) for
	// the auth server.
	Preference types.AuthPreference

	// AuditConfig stores cluster audit configuration.
	AuditConfig types.ClusterAuditConfig

	// NetworkingConfig stores cluster networking configuration.
	NetworkingConfig types.ClusterNetworkingConfig

	// SessionRecordingConfig stores session recording configuration.
	SessionRecordingConfig types.SessionRecordingConfig

	// LicenseFile is a full path to the license file
	LicenseFile string

	// PublicAddrs affects the SSH host principals and DNS names added to the SSH and TLS certs.
	PublicAddrs []utils.NetAddr

	// KeyStore configuration. Handles CA private keys which may be held in a HSM.
	KeyStore keystore.Config
}

// SSHConfig configures SSH server node role
type SSHConfig struct {
	Enabled               bool
	Addr                  utils.NetAddr
	Namespace             string
	Shell                 string
	Limiter               limiter.Config
	Labels                map[string]string
	CmdLabels             services.CommandLabels
	PermitUserEnvironment bool

	// PAM holds PAM configuration for Teleport.
	PAM *pam.Config

	// PublicAddrs affects the SSH host principals and DNS names added to the SSH and TLS certs.
	PublicAddrs []utils.NetAddr

	// BPF holds BPF configuration for Teleport.
	BPF *bpf.Config

	// RestrictedSession holds kernel objects restrictions for Teleport.
	RestrictedSession *restricted.Config

	// AllowTCPForwarding indicates that TCP port forwarding is allowed on this node
	AllowTCPForwarding bool

	// IdleTimeoutMessage is sent to the client when a session expires due to
	// the inactivity timeout expiring. The empty string indicates that no
	// timeout message will be sent.
	IdleTimeoutMessage string
}

// KubeConfig specifies configuration for kubernetes service
type KubeConfig struct {
	// Enabled turns kubernetes service role on or off for this process
	Enabled bool

	// ListenAddr is the address to listen on for incoming kubernetes requests.
	// Optional.
	ListenAddr *utils.NetAddr

	// PublicAddrs is a list of the public addresses the Teleport kubernetes
	// service can be reached by the proxy service.
	PublicAddrs []utils.NetAddr

	// KubeClusterName is the name of a kubernetes cluster this proxy is running
	// in. If empty, defaults to the Teleport cluster name.
	KubeClusterName string

	// KubeconfigPath is a path to kubeconfig
	KubeconfigPath string

	// Labels are used for RBAC on clusters.
	StaticLabels  map[string]string
	DynamicLabels services.CommandLabels

	// Limiter limits the connection and request rates.
	Limiter limiter.Config

	// CheckImpersonationPermissions is an optional override to the default
	// impersonation permissions check, for use in testing.
	CheckImpersonationPermissions proxy.ImpersonationPermissionsChecker
}

// DatabasesConfig configures the database proxy service.
type DatabasesConfig struct {
	// Enabled enables the database proxy service.
	Enabled bool
	// Databases is a list of databases proxied by this service.
	Databases []Database
	// ResourceMatchers match cluster database resources.
	ResourceMatchers []services.ResourceMatcher
	// AWSMatchers match AWS hosted databases.
	AWSMatchers []services.AWSMatcher
	// Limiter limits the connection and request rates.
	Limiter limiter.Config
}

// Database represents a single database that's being proxied.
type Database struct {
	// Name is the database name, used to refer to in CLI.
	Name string
	// Description is a free-form database description.
	Description string
	// Protocol is the database type, e.g. postgres or mysql.
	Protocol string
	// URI is the database endpoint to connect to.
	URI string
	// StaticLabels is a map of database static labels.
	StaticLabels map[string]string
	// DynamicLabels is a list of database dynamic labels.
	DynamicLabels services.CommandLabels
	// TLS keeps database connection TLS configuration.
	TLS DatabaseTLS
	// AWS contains AWS specific settings for RDS/Aurora/Redshift databases.
	AWS DatabaseAWS
	// GCP contains GCP specific settings for Cloud SQL databases.
	GCP DatabaseGCP
}

// TLSMode defines all possible database verification modes.
type TLSMode string

const (
	// VerifyFull is the strictest. Verifies certificate and server name.
	VerifyFull TLSMode = "verify-full"
	// VerifyCA checks the certificate, but skips the server name verification.
	VerifyCA TLSMode = "verify-ca"
	// Insecure accepts any certificate.
	Insecure TLSMode = "insecure"
)

// AllTLSModes keeps all possible database TLS modes for easy access.
var AllTLSModes = []TLSMode{VerifyFull, VerifyCA, Insecure}

// CheckAndSetDefaults check if TLSMode holds a correct value. If the value is not set
// VerifyFull is set as a default. BadParameter error is returned if value set is incorrect.
func (m *TLSMode) CheckAndSetDefaults() error {
	switch *m {
	case "": // Use VerifyFull if not set.
		*m = VerifyFull
	case VerifyFull, VerifyCA, Insecure:
		// Correct value, do nothing.
	default:
		return trace.BadParameter("provided incorrect TLSMode value. Correct values are: %v", AllTLSModes)
	}

	return nil
}

// ToProto returns a matching protobuf type or VerifyFull for empty value.
func (m TLSMode) ToProto() types.DatabaseTLSMode {
	switch m {
	case VerifyCA:
		return types.DatabaseTLSMode_VERIFY_CA
	case Insecure:
		return types.DatabaseTLSMode_INSECURE
	default: // VerifyFull
		return types.DatabaseTLSMode_VERIFY_FULL
	}
}

// DatabaseTLS keeps TLS settings used when connecting to database.
type DatabaseTLS struct {
	// Mode is the TLS connection mode. See TLSMode for more details.
	Mode TLSMode
	// ServerName allows providing custom server name.
	// This name will override DNS name when validating certificate presented by the database.
	ServerName string
	// CACert is an optional database CA certificate.
	CACert []byte
}

// DatabaseAWS contains AWS specific settings for RDS/Aurora databases.
type DatabaseAWS struct {
	// Region is the cloud region database is running in when using AWS RDS.
	Region string
	// Redshift contains Redshift specific settings.
	Redshift DatabaseAWSRedshift
	// RDS contains RDS specific settings.
	RDS DatabaseAWSRDS
}

// DatabaseAWSRedshift contains AWS Redshift specific settings.
type DatabaseAWSRedshift struct {
	// ClusterID is the Redshift cluster identifier.
	ClusterID string
}

// DatabaseAWSRDS contains AWS RDS specific settings.
type DatabaseAWSRDS struct {
	// InstanceID is the RDS instance identifier.
	InstanceID string
	// ClusterID is the RDS cluster (Aurora) identifier.
	ClusterID string
}

// DatabaseGCP contains GCP specific settings for Cloud SQL databases.
type DatabaseGCP struct {
	// ProjectID is the GCP project ID where the database is deployed.
	ProjectID string
	// InstanceID is the Cloud SQL instance ID.
	InstanceID string
}

// CheckAndSetDefaults validates the database proxy configuration.
func (d *Database) CheckAndSetDefaults() error {
	if d.Name == "" {
		return trace.BadParameter("empty database name")
	}
	// Unlike application access proxy, database proxy name doesn't necessarily
	// need to be a valid subdomain but use the same validation logic for the
	// simplicity and consistency.
	if errs := validation.IsDNS1035Label(d.Name); len(errs) > 0 {
		return trace.BadParameter("invalid database %q name: %v", d.Name, errs)
	}
	if !apiutils.SliceContainsStr(defaults.DatabaseProtocols, d.Protocol) {
		return trace.BadParameter("unsupported database %q protocol %q, supported are: %v",
			d.Name, d.Protocol, defaults.DatabaseProtocols)
	}
	// Mark the database as coming from the static configuration.
	if d.StaticLabels == nil {
		d.StaticLabels = make(map[string]string)
	}
	d.StaticLabels[types.OriginLabel] = types.OriginConfigFile
	// For MongoDB we support specifying either server address or connection
	// string in the URI which is useful when connecting to a replica set.
	if d.Protocol == defaults.ProtocolMongoDB &&
		(strings.HasPrefix(d.URI, connstring.SchemeMongoDB+"://") ||
			strings.HasPrefix(d.URI, connstring.SchemeMongoDBSRV+"://")) {
		connString, err := connstring.ParseAndValidate(d.URI)
		if err != nil {
			return trace.BadParameter("invalid MongoDB database %q connection string %q: %v",
				d.Name, d.URI, err)
		}
		// Validate read preference to catch typos early.
		if connString.ReadPreference != "" {
			if _, err := readpref.ModeFromString(connString.ReadPreference); err != nil {
				return trace.BadParameter("invalid MongoDB database %q read preference %q",
					d.Name, connString.ReadPreference)
			}
		}
	} else if _, _, err := net.SplitHostPort(d.URI); err != nil {
		return trace.BadParameter("invalid database %q address %q: %v",
			d.Name, d.URI, err)
	}
	if len(d.TLS.CACert) != 0 {
		if _, err := tlsca.ParseCertificatePEM(d.TLS.CACert); err != nil {
			return trace.BadParameter("provided database %q CA doesn't appear to be a valid x509 certificate: %v",
				d.Name, err)
		}
	}
	if err := d.TLS.Mode.CheckAndSetDefaults(); err != nil {
		return trace.Wrap(err)
	}

	// Validate Cloud SQL specific configuration.
	switch {
	case d.GCP.ProjectID != "" && d.GCP.InstanceID == "":
		return trace.BadParameter("missing Cloud SQL instance ID for database %q", d.Name)
	case d.GCP.ProjectID == "" && d.GCP.InstanceID != "":
		return trace.BadParameter("missing Cloud SQL project ID for database %q", d.Name)
	}
	return nil
}

// AppsConfig configures application proxy service.
type AppsConfig struct {
	// Enabled enables application proxying service.
	Enabled bool

	// DebugApp enabled a header dumping debugging application.
	DebugApp bool

	// Apps is the list of applications that are being proxied.
	Apps []App

	// ResourceMatchers match cluster database resources.
	ResourceMatchers []services.ResourceMatcher
}

// App is the specific application that will be proxied by the application
// service. This needs to exist because if the "config" package tries to
// directly create a services.App it will get into circular imports.
type App struct {
	// Name of the application.
	Name string

	// Description is the app description.
	Description string

	// URI is the internal address of the application.
	URI string

	// Public address of the application. This is the address users will access
	// the application at.
	PublicAddr string

	// StaticLabels is a map of static labels to apply to this application.
	StaticLabels map[string]string

	// DynamicLabels is a list of dynamic labels to apply to this application.
	DynamicLabels services.CommandLabels

	// InsecureSkipVerify is used to skip validating the server's certificate.
	InsecureSkipVerify bool

	// Rewrite defines a block that is used to rewrite requests and responses.
	Rewrite *Rewrite
}

// CheckAndSetDefaults validates an application.
func (a *App) CheckAndSetDefaults() error {
	if a.Name == "" {
		return trace.BadParameter("missing application name")
	}
	if a.URI == "" {
		return trace.BadParameter("missing application %q URI", a.Name)
	}
	// Check if the application name is a valid subdomain. Don't allow names that
	// are invalid subdomains because for trusted clusters the name is used to
	// construct the domain that the application will be available at.
	if errs := validation.IsDNS1035Label(a.Name); len(errs) > 0 {
		return trace.BadParameter("application name %q must be a valid DNS subdomain: https://goteleport.com/teleport/docs/application-access/#application-name", a.Name)
	}
	// Parse and validate URL.
	if _, err := url.Parse(a.URI); err != nil {
		return trace.BadParameter("application %q URI invalid: %v", a.Name, err)
	}
	// If a port was specified or an IP address was provided for the public
	// address, return an error.
	if a.PublicAddr != "" {
		if _, _, err := net.SplitHostPort(a.PublicAddr); err == nil {
			return trace.BadParameter("application %q public_addr %q can not contain a port, applications will be available on the same port as the web proxy", a.Name, a.PublicAddr)
		}
		if net.ParseIP(a.PublicAddr) != nil {
			return trace.BadParameter("application %q public_addr %q can not be an IP address, Teleport Application Access uses DNS names for routing", a.Name, a.PublicAddr)
		}
	}
	// Mark the app as coming from the static configuration.
	if a.StaticLabels == nil {
		a.StaticLabels = make(map[string]string)
	}
	a.StaticLabels[types.OriginLabel] = types.OriginConfigFile
	// Make sure there are no reserved headers in the rewrite configuration.
	// They wouldn't be rewritten even if we allowed them here but catch it
	// early and let the user know.
	if a.Rewrite != nil {
		for _, h := range a.Rewrite.Headers {
			if common.IsReservedHeader(h.Name) {
				return trace.BadParameter("invalid application %q header rewrite configuration: header %q is reserved and can't be rewritten",
					a.Name, http.CanonicalHeaderKey(h.Name))
			}
		}
	}
	return nil
}

// MetricsConfig specifies configuration for the metrics service
type MetricsConfig struct {
	// Enabled turns the metrics service role on or off for this process
	Enabled bool

	// ListenAddr is the address to listen on for incoming metrics requests.
	// Optional.
	ListenAddr *utils.NetAddr

	// MTLS turns mTLS on the metrics service on or off
	MTLS bool

	// KeyPairs are the key and certificate pairs that the metrics service will
	// use for mTLS.
	// Used in conjunction with MTLS = true
	KeyPairs []KeyPairPath

	// CACerts are prometheus ca certs
	// use for mTLS.
	// Used in conjunction with MTLS = true
	CACerts []string
}

// WindowsDesktopConfig specifies the configuration for the Windows Desktop
// Access service.
type WindowsDesktopConfig struct {
	Enabled bool
	// ListenAddr is the address to listed on for incoming desktop connections.
	ListenAddr utils.NetAddr
	// PublicAddrs is a list of advertised public addresses of the service.
	PublicAddrs []utils.NetAddr
	// LDAP is the LDAP connection parameters.
	LDAP LDAPConfig

	// Discovery configures automatic desktop discovery via LDAP.
	Discovery LDAPDiscoveryConfig

	// Hosts is an optional list of static Windows hosts to expose through this
	// service.
	Hosts []utils.NetAddr
	// ConnLimiter limits the connection and request rates.
	ConnLimiter limiter.Config
	// HostLabels specifies rules that are used to apply labels to Windows hosts.
	HostLabels HostLabelRules
}

type LDAPDiscoveryConfig struct {
	// BaseDN is the base DN to search for desktops.
	// Use the value '*' to search from the root of the domain,
	// or leave blank to disable desktop discovery.
	BaseDN string `yaml:"base_dn"`
	// Filters are additional LDAP filters to apply to the search.
	// See: https://ldap.com/ldap-filters/
	Filters []string `yaml:"filters"`
}

// HostLabelRules is a collection of rules describing how to apply labels to hosts.
type HostLabelRules []HostLabelRule

// LabelsForHost returns the set of all labels that should be applied
// to the specified host. If multiple rules match and specify the same
// label keys, the value will be that of the last matching rule.
func (h HostLabelRules) LabelsForHost(host string) map[string]string {
	// TODO(zmb3): consider memoizing this call - the set of rules doesn't
	// change, so it may be worth not matching regexps on each heartbeat.
	result := make(map[string]string)
	for _, rule := range h {
		if rule.Regexp.MatchString(host) {
			for k, v := range rule.Labels {
				result[k] = v
			}
		}
	}
	return result
}

// HostLabelRule specifies a set of labels that should be applied to
// hosts matching the provided regexp.
type HostLabelRule struct {
	Regexp *regexp.Regexp
	Labels map[string]string
}

// LDAPConfig is the LDAP connection parameters.
type LDAPConfig struct {
	// Addr is the address:port of the LDAP server (typically port 389).
	Addr string
	// Domain is the ActiveDirectory domain name.
	Domain string
	// Username for LDAP authentication.
	Username string
	// Password for LDAP authentication.
	Password string
	// InsecureSkipVerify decides whether whether we skip verifying with the LDAP server's CA when making the LDAPS connection.
	InsecureSkipVerify bool
	// CA is an optional CA cert to be used for verification if InsecureSkipVerify is set to false.
	CA *x509.Certificate
}

// Rewrite is a list of rewriting rules to apply to requests and responses.
type Rewrite struct {
	// Redirect is a list of hosts that should be rewritten to the public address.
	Redirect []string
	// Headers is a list of extra headers to inject in the request.
	Headers []Header
}

// Header represents a single http header passed over to the proxied application.
type Header struct {
	// Name is the http header name.
	Name string
	// Value is the http header value.
	Value string
}

// ParseHeader parses the provided string as a http header.
func ParseHeader(header string) (*Header, error) {
	parts := strings.SplitN(header, ":", 2)
	if len(parts) != 2 {
		return nil, trace.BadParameter("failed to parse %q as http header", header)
	}
	name := strings.TrimSpace(parts[0])
	value := strings.TrimSpace(parts[1])
	if !httpguts.ValidHeaderFieldName(name) {
		return nil, trace.BadParameter("invalid http header name: %q", header)
	}
	if !httpguts.ValidHeaderFieldValue(value) {
		return nil, trace.BadParameter("invalid http header value: %q", header)
	}
	return &Header{
		Name:  name,
		Value: value,
	}, nil
}

// ParseHeaders parses the provided list as http headers.
func ParseHeaders(headers []string) (headersOut []Header, err error) {
	for _, header := range headers {
		h, err := ParseHeader(header)
		if err != nil {
			return nil, trace.Wrap(err)
		}
		headersOut = append(headersOut, *h)
	}
	return headersOut, nil
}

// MakeDefaultConfig creates a new Config structure and populates it with defaults
func MakeDefaultConfig() (config *Config) {
	config = &Config{}
	ApplyDefaults(config)
	return config
}

// ApplyDefaults applies default values to the existing config structure
func ApplyDefaults(cfg *Config) {
	// Get defaults for Cipher, Kex algorithms, and MAC algorithms from
	// golang.org/x/crypto/ssh default config.
	var sc ssh.Config
	sc.SetDefaults()

	if cfg.Log == nil {
		cfg.Log = utils.NewLogger()
	}

	// Remove insecure and (borderline insecure) cryptographic primitives from
	// default configuration. These can still be added back in file configuration by
	// users, but not supported by default by Teleport. See #1856 for more
	// details.
	kex := utils.RemoveFromSlice(sc.KeyExchanges,
		defaults.DiffieHellmanGroup1SHA1,
		defaults.DiffieHellmanGroup14SHA1)
	macs := utils.RemoveFromSlice(sc.MACs,
		defaults.HMACSHA1,
		defaults.HMACSHA196)

	hostname, err := os.Hostname()
	if err != nil {
		hostname = "localhost"
		cfg.Log.Errorf("Failed to determine hostname: %v.", err)
	}

	// Global defaults.
	cfg.Hostname = hostname
	cfg.DataDir = defaults.DataDir
	cfg.Console = os.Stdout
	cfg.CipherSuites = utils.DefaultCipherSuites()
	cfg.Ciphers = sc.Ciphers
	cfg.KEXAlgorithms = kex
	cfg.MACAlgorithms = macs

	// Auth service defaults.
	cfg.Auth.Enabled = true
	cfg.Auth.SSHAddr = *defaults.AuthListenAddr()
	cfg.Auth.StorageConfig.Type = lite.GetName()
	cfg.Auth.StorageConfig.Params = backend.Params{defaults.BackendPath: filepath.Join(cfg.DataDir, defaults.BackendDir)}
	cfg.Auth.StaticTokens = types.DefaultStaticTokens()
	cfg.Auth.AuditConfig = types.DefaultClusterAuditConfig()
	cfg.Auth.NetworkingConfig = types.DefaultClusterNetworkingConfig()
	cfg.Auth.SessionRecordingConfig = types.DefaultSessionRecordingConfig()
	cfg.Auth.Preference = types.DefaultAuthPreference()
	defaults.ConfigureLimiter(&cfg.Auth.Limiter)
	cfg.Auth.LicenseFile = filepath.Join(cfg.DataDir, defaults.LicenseFile)

	cfg.Proxy.WebAddr = *defaults.ProxyWebListenAddr()
	// Proxy service defaults.
	cfg.Proxy.Enabled = true
	cfg.Proxy.Kube.Enabled = false

	defaults.ConfigureLimiter(&cfg.Proxy.Limiter)

	// SSH service defaults.
	cfg.SSH.Enabled = true
	cfg.SSH.Shell = defaults.DefaultShell
	defaults.ConfigureLimiter(&cfg.SSH.Limiter)
	cfg.SSH.PAM = &pam.Config{Enabled: false}
	cfg.SSH.BPF = &bpf.Config{Enabled: false}
	cfg.SSH.RestrictedSession = &restricted.Config{Enabled: false}
	cfg.SSH.AllowTCPForwarding = true

	// Kubernetes service defaults.
	cfg.Kube.Enabled = false
	defaults.ConfigureLimiter(&cfg.Kube.Limiter)

	// Apps service defaults. It's disabled by default.
	cfg.Apps.Enabled = false

	// Databases proxy service is disabled by default.
	cfg.Databases.Enabled = false
	defaults.ConfigureLimiter(&cfg.Databases.Limiter)

	// Metrics service defaults.
	cfg.Metrics.Enabled = false

	// Windows desktop service is disabled by default.
	cfg.WindowsDesktop.Enabled = false
	defaults.ConfigureLimiter(&cfg.WindowsDesktop.ConnLimiter)

	cfg.RotationConnectionInterval = defaults.HighResPollingPeriod
	cfg.RestartThreshold = Rate{
		Amount: defaults.MaxConnectionErrorsBeforeRestart,
		Time:   defaults.ConnectionErrorMeasurementPeriod,
	}
	cfg.MaxRetryPeriod = defaults.MaxWatcherBackoff
	cfg.ConnectFailureC = make(chan time.Duration, 1)
}

// ApplyFIPSDefaults updates default configuration to be FedRAMP/FIPS 140-2
// compliant.
func ApplyFIPSDefaults(cfg *Config) {
	cfg.FIPS = true

	// Update TLS and SSH cryptographic primitives.
	cfg.CipherSuites = defaults.FIPSCipherSuites
	cfg.Ciphers = defaults.FIPSCiphers
	cfg.KEXAlgorithms = defaults.FIPSKEXAlgorithms
	cfg.MACAlgorithms = defaults.FIPSMACAlgorithms

	// Only SSO based authentication is supported in FIPS mode. The SSO
	// provider is where any FedRAMP/FIPS 140-2 compliance (like password
	// complexity) should be enforced.
	cfg.Auth.Preference.SetAllowLocalAuth(false)

	// Update cluster configuration to record sessions at node, this way the
	// entire cluster is FedRAMP/FIPS 140-2 compliant.
	cfg.Auth.SessionRecordingConfig.SetMode(types.RecordAtNode)
}

// JoinMethod is the method the instance will use to join the auth server.
type JoinMethod int

const (
	// JoinMethodToken means the instance will use a basic token.
	JoinMethodToken JoinMethod = iota
	// JoinMethodEC2 means the instance will use Simplified Node Joining and send an
	// EC2 Instance Identity Document.
	JoinMethodEC2
)