AdGuardHome/internal/dnsforward/config.go

645 lines
20 KiB
Go

package dnsforward
import (
"crypto/tls"
"crypto/x509"
"fmt"
"net"
"net/netip"
"os"
"strings"
"time"
"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
"github.com/AdguardTeam/AdGuardHome/internal/aghtls"
"github.com/AdguardTeam/AdGuardHome/internal/filtering"
"github.com/AdguardTeam/dnsproxy/proxy"
"github.com/AdguardTeam/dnsproxy/upstream"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
"github.com/AdguardTeam/golibs/netutil"
"github.com/AdguardTeam/golibs/stringutil"
"github.com/AdguardTeam/golibs/timeutil"
"github.com/ameshkov/dnscrypt/v2"
"golang.org/x/exp/slices"
)
// BlockingMode is an enum of all allowed blocking modes.
type BlockingMode string
// Allowed blocking modes.
const (
// BlockingModeCustomIP means respond with a custom IP address.
BlockingModeCustomIP BlockingMode = "custom_ip"
// BlockingModeDefault is the same as BlockingModeNullIP for
// Adblock-style rules, but responds with the IP address specified in
// the rule when blocked by an `/etc/hosts`-style rule.
BlockingModeDefault BlockingMode = "default"
// BlockingModeNullIP means respond with a zero IP address: "0.0.0.0"
// for A requests and "::" for AAAA ones.
BlockingModeNullIP BlockingMode = "null_ip"
// BlockingModeNXDOMAIN means respond with the NXDOMAIN code.
BlockingModeNXDOMAIN BlockingMode = "nxdomain"
// BlockingModeREFUSED means respond with the REFUSED code.
BlockingModeREFUSED BlockingMode = "refused"
)
// FilteringConfig represents the DNS filtering configuration of AdGuard Home
// The zero FilteringConfig is empty and ready for use.
type FilteringConfig struct {
// Callbacks for other modules
// FilterHandler is an optional additional filtering callback.
FilterHandler func(clientAddr net.IP, clientID string, settings *filtering.Settings) `yaml:"-"`
// GetCustomUpstreamByClient is a callback that returns upstreams
// configuration based on the client IP address or ClientID. It returns
// nil if there are no custom upstreams for the client.
GetCustomUpstreamByClient func(id string) (conf *proxy.UpstreamConfig, err error) `yaml:"-"`
// Protection configuration
// ProtectionEnabled defines whether or not use any of filtering features.
ProtectionEnabled bool `yaml:"protection_enabled"`
// BlockingMode defines the way how blocked responses are constructed.
BlockingMode BlockingMode `yaml:"blocking_mode"`
// BlockingIPv4 is the IP address to be returned for a blocked A request.
BlockingIPv4 net.IP `yaml:"blocking_ipv4"`
// BlockingIPv6 is the IP address to be returned for a blocked AAAA
// request.
BlockingIPv6 net.IP `yaml:"blocking_ipv6"`
// BlockedResponseTTL is the time-to-live value for blocked responses. If
// 0, then default value is used (3600).
BlockedResponseTTL uint32 `yaml:"blocked_response_ttl"`
// ParentalBlockHost is the IP (or domain name) which is used to respond to
// DNS requests blocked by parental control.
ParentalBlockHost string `yaml:"parental_block_host"`
// SafeBrowsingBlockHost is the IP (or domain name) which is used to
// respond to DNS requests blocked by safe-browsing.
SafeBrowsingBlockHost string `yaml:"safebrowsing_block_host"`
// Anti-DNS amplification
// Ratelimit is the maximum number of requests per second from a given IP
// (0 to disable).
Ratelimit uint32 `yaml:"ratelimit"`
// RatelimitWhitelist is the list of whitelisted client IP addresses.
RatelimitWhitelist []string `yaml:"ratelimit_whitelist"`
// RefuseAny, if true, refuse ANY requests.
RefuseAny bool `yaml:"refuse_any"`
// Upstream DNS servers configuration
// UpstreamDNS is the list of upstream DNS servers.
UpstreamDNS []string `yaml:"upstream_dns"`
// UpstreamDNSFileName, if set, points to the file which contains upstream
// DNS servers.
UpstreamDNSFileName string `yaml:"upstream_dns_file"`
// BootstrapDNS is the list of bootstrap DNS servers for DoH and DoT
// resolvers (plain DNS only).
BootstrapDNS []string `yaml:"bootstrap_dns"`
// AllServers, if true, parallel queries to all configured upstream servers
// are enabled.
AllServers bool `yaml:"all_servers"`
// FastestAddr, if true, use Fastest Address algorithm.
FastestAddr bool `yaml:"fastest_addr"`
// FastestTimeout replaces the default timeout for dialing IP addresses
// when FastestAddr is true.
FastestTimeout timeutil.Duration `yaml:"fastest_timeout"`
// Access settings
// AllowedClients is the slice of IP addresses, CIDR networks, and
// ClientIDs of allowed clients. If not empty, only these clients are
// allowed, and [FilteringConfig.DisallowedClients] are ignored.
AllowedClients []string `yaml:"allowed_clients"`
// DisallowedClients is the slice of IP addresses, CIDR networks, and
// ClientIDs of disallowed clients.
DisallowedClients []string `yaml:"disallowed_clients"`
// BlockedHosts is the list of hosts that should be blocked.
BlockedHosts []string `yaml:"blocked_hosts"`
// TrustedProxies is the list of IP addresses and CIDR networks to detect
// proxy servers addresses the DoH requests from which should be handled.
// The value of nil or an empty slice for this field makes Proxy not trust
// any address.
TrustedProxies []string `yaml:"trusted_proxies"`
// DNS cache settings
// CacheSize is the DNS cache size (in bytes).
CacheSize uint32 `yaml:"cache_size"`
// CacheMinTTL is the override TTL value (minimum) received from upstream
// server.
CacheMinTTL uint32 `yaml:"cache_ttl_min"`
// CacheMaxTTL is the override TTL value (maximum) received from upstream
// server.
CacheMaxTTL uint32 `yaml:"cache_ttl_max"`
// CacheOptimistic defines if optimistic cache mechanism should be used.
CacheOptimistic bool `yaml:"cache_optimistic"`
// Other settings
// BogusNXDomain is the list of IP addresses, responses with them will be
// transformed to NXDOMAIN.
BogusNXDomain []string `yaml:"bogus_nxdomain"`
// AAAADisabled, if true, respond with an empty answer to all AAAA
// requests.
AAAADisabled bool `yaml:"aaaa_disabled"`
// EnableDNSSEC, if true, set AD flag in outcoming DNS request.
EnableDNSSEC bool `yaml:"enable_dnssec"`
// EDNSClientSubnet is the settings list for EDNS Client Subnet.
EDNSClientSubnet *EDNSClientSubnet `yaml:"edns_client_subnet"`
// MaxGoroutines is the max number of parallel goroutines for processing
// incoming requests.
MaxGoroutines uint32 `yaml:"max_goroutines"`
// HandleDDR, if true, handle DDR requests
HandleDDR bool `yaml:"handle_ddr"`
// IpsetList is the ipset configuration that allows AdGuard Home to add IP
// addresses of the specified domain names to an ipset list. Syntax:
//
// DOMAIN[,DOMAIN].../IPSET_NAME
//
// This field is ignored if [IpsetListFileName] is set.
IpsetList []string `yaml:"ipset"`
// IpsetListFileName, if set, points to the file with ipset configuration.
// The format is the same as in [IpsetList].
IpsetListFileName string `yaml:"ipset_file"`
}
// EDNSClientSubnet is the settings list for EDNS Client Subnet.
type EDNSClientSubnet struct {
// CustomIP for EDNS Client Subnet.
CustomIP string `yaml:"custom_ip"`
// Enabled defines if EDNS Client Subnet is enabled.
Enabled bool `yaml:"enabled"`
// UseCustom defines if CustomIP should be used.
UseCustom bool `yaml:"use_custom"`
}
// TLSConfig is the TLS configuration for HTTPS, DNS-over-HTTPS, and DNS-over-TLS
type TLSConfig struct {
cert tls.Certificate
TLSListenAddrs []*net.TCPAddr `yaml:"-" json:"-"`
QUICListenAddrs []*net.UDPAddr `yaml:"-" json:"-"`
HTTPSListenAddrs []*net.TCPAddr `yaml:"-" json:"-"`
// PEM-encoded certificates chain
CertificateChain string `yaml:"certificate_chain" json:"certificate_chain"`
// PEM-encoded private key
PrivateKey string `yaml:"private_key" json:"private_key"`
CertificatePath string `yaml:"certificate_path" json:"certificate_path"`
PrivateKeyPath string `yaml:"private_key_path" json:"private_key_path"`
CertificateChainData []byte `yaml:"-" json:"-"`
PrivateKeyData []byte `yaml:"-" json:"-"`
// ServerName is the hostname of the server. Currently, it is only being
// used for ClientID checking and Discovery of Designated Resolvers (DDR).
ServerName string `yaml:"-" json:"-"`
// DNS names from certificate (SAN) or CN value from Subject
dnsNames []string
// OverrideTLSCiphers, when set, contains the names of the cipher suites to
// use. If the slice is empty, the default safe suites are used.
OverrideTLSCiphers []string `yaml:"override_tls_ciphers,omitempty" json:"-"`
// StrictSNICheck controls if the connections with SNI mismatching the
// certificate's ones should be rejected.
StrictSNICheck bool `yaml:"strict_sni_check" json:"-"`
// hasIPAddrs is set during the certificate parsing and is true if the
// configured certificate contains at least a single IP address.
hasIPAddrs bool
}
// DNSCryptConfig is the DNSCrypt server configuration struct.
type DNSCryptConfig struct {
ResolverCert *dnscrypt.Cert
ProviderName string
UDPListenAddrs []*net.UDPAddr
TCPListenAddrs []*net.TCPAddr
Enabled bool
}
// ServerConfig represents server configuration.
// The zero ServerConfig is empty and ready for use.
type ServerConfig struct {
UDPListenAddrs []*net.UDPAddr // UDP listen address
TCPListenAddrs []*net.TCPAddr // TCP listen address
UpstreamConfig *proxy.UpstreamConfig // Upstream DNS servers config
OnDNSRequest func(d *proxy.DNSContext)
FilteringConfig
TLSConfig
DNSCryptConfig
TLSAllowUnencryptedDoH bool
// UpstreamTimeout is the timeout for querying upstream servers.
UpstreamTimeout time.Duration
TLSv12Roots *x509.CertPool // list of root CAs for TLSv1.2
// TLSCiphers are the IDs of TLS cipher suites to use.
TLSCiphers []uint16
// Called when the configuration is changed by HTTP request
ConfigModified func()
// Register an HTTP handler
HTTPRegister aghhttp.RegisterFunc
// LocalPTRResolvers is a slice of addresses to be used as upstreams for
// resolving PTR queries for local addresses.
LocalPTRResolvers []string
// DNS64Prefixes is a slice of NAT64 prefixes to be used for DNS64.
DNS64Prefixes []netip.Prefix
// ResolveClients signals if the RDNS should resolve clients' addresses.
ResolveClients bool
// UsePrivateRDNS defines if the PTR requests for unknown addresses from
// locally-served networks should be resolved via private PTR resolvers.
UsePrivateRDNS bool
// UseDNS64 defines if DNS64 is enabled for incoming requests.
UseDNS64 bool
// ServeHTTP3 defines if HTTP/3 is be allowed for incoming requests.
ServeHTTP3 bool
// UseHTTP3Upstreams defines if HTTP/3 is be allowed for DNS-over-HTTPS
// upstreams.
UseHTTP3Upstreams bool
}
// if any of ServerConfig values are zero, then default values from below are used
var defaultValues = ServerConfig{
UDPListenAddrs: []*net.UDPAddr{{Port: 53}},
TCPListenAddrs: []*net.TCPAddr{{Port: 53}},
FilteringConfig: FilteringConfig{BlockedResponseTTL: 3600},
}
// createProxyConfig creates and validates configuration for the main proxy.
func (s *Server) createProxyConfig() (conf proxy.Config, err error) {
srvConf := s.conf
conf = proxy.Config{
UDPListenAddr: srvConf.UDPListenAddrs,
TCPListenAddr: srvConf.TCPListenAddrs,
HTTP3: srvConf.ServeHTTP3,
Ratelimit: int(srvConf.Ratelimit),
RatelimitWhitelist: srvConf.RatelimitWhitelist,
RefuseAny: srvConf.RefuseAny,
TrustedProxies: srvConf.TrustedProxies,
CacheMinTTL: srvConf.CacheMinTTL,
CacheMaxTTL: srvConf.CacheMaxTTL,
CacheOptimistic: srvConf.CacheOptimistic,
UpstreamConfig: srvConf.UpstreamConfig,
BeforeRequestHandler: s.beforeRequestHandler,
RequestHandler: s.handleDNSRequest,
EnableEDNSClientSubnet: srvConf.EDNSClientSubnet.Enabled,
MaxGoroutines: int(srvConf.MaxGoroutines),
UseDNS64: srvConf.UseDNS64,
DNS64Prefs: srvConf.DNS64Prefixes,
}
if srvConf.EDNSClientSubnet.UseCustom {
// TODO(s.chzhen): Add wrapper around netip.Addr.
var ip net.IP
ip, err = netutil.ParseIP(srvConf.EDNSClientSubnet.CustomIP)
if err != nil {
return conf, fmt.Errorf("edns: %w", err)
}
// TODO(s.chzhen): Use netip.Addr instead of net.IP inside dnsproxy.
conf.EDNSAddr = ip
}
if srvConf.CacheSize != 0 {
conf.CacheEnabled = true
conf.CacheSizeBytes = int(srvConf.CacheSize)
}
setProxyUpstreamMode(
&conf,
srvConf.AllServers,
srvConf.FastestAddr,
srvConf.FastestTimeout.Duration,
)
for i, s := range srvConf.BogusNXDomain {
var subnet *net.IPNet
subnet, err = netutil.ParseSubnet(s)
if err != nil {
log.Error("subnet at index %d: %s", i, err)
continue
}
conf.BogusNXDomain = append(conf.BogusNXDomain, subnet)
}
err = s.prepareTLS(&conf)
if err != nil {
return conf, fmt.Errorf("validating tls: %w", err)
}
if c := srvConf.DNSCryptConfig; c.Enabled {
conf.DNSCryptUDPListenAddr = c.UDPListenAddrs
conf.DNSCryptTCPListenAddr = c.TCPListenAddrs
conf.DNSCryptProviderName = c.ProviderName
conf.DNSCryptResolverCert = c.ResolverCert
}
if conf.UpstreamConfig == nil || len(conf.UpstreamConfig.Upstreams) == 0 {
return conf, errors.Error("no default upstream servers configured")
}
return conf, nil
}
const (
defaultSafeBrowsingBlockHost = "standard-block.dns.adguard.com"
defaultParentalBlockHost = "family-block.dns.adguard.com"
)
// initDefaultSettings initializes default settings if nothing
// is configured
func (s *Server) initDefaultSettings() {
if len(s.conf.UpstreamDNS) == 0 {
s.conf.UpstreamDNS = defaultDNS
}
if len(s.conf.BootstrapDNS) == 0 {
s.conf.BootstrapDNS = defaultBootstrap
}
if s.conf.ParentalBlockHost == "" {
s.conf.ParentalBlockHost = defaultParentalBlockHost
}
if s.conf.SafeBrowsingBlockHost == "" {
s.conf.SafeBrowsingBlockHost = defaultSafeBrowsingBlockHost
}
if s.conf.UDPListenAddrs == nil {
s.conf.UDPListenAddrs = defaultValues.UDPListenAddrs
}
if s.conf.TCPListenAddrs == nil {
s.conf.TCPListenAddrs = defaultValues.TCPListenAddrs
}
if len(s.conf.BlockedHosts) == 0 {
s.conf.BlockedHosts = defaultBlockedHosts
}
if s.conf.UpstreamTimeout == 0 {
s.conf.UpstreamTimeout = DefaultTimeout
}
}
// UpstreamHTTPVersions returns the HTTP versions for upstream configuration
// depending on configuration.
func UpstreamHTTPVersions(http3 bool) (v []upstream.HTTPVersion) {
if !http3 {
return upstream.DefaultHTTPVersions
}
return []upstream.HTTPVersion{
upstream.HTTPVersion3,
upstream.HTTPVersion2,
upstream.HTTPVersion11,
}
}
// prepareUpstreamSettings - prepares upstream DNS server settings
func (s *Server) prepareUpstreamSettings() error {
// We're setting a customized set of RootCAs. The reason is that Go default
// mechanism of loading TLS roots does not always work properly on some
// routers so we're loading roots manually and pass it here.
//
// See [aghtls.SystemRootCAs].
upstream.RootCAs = s.conf.TLSv12Roots
upstream.CipherSuites = s.conf.TLSCiphers
// Load upstreams either from the file, or from the settings
var upstreams []string
if s.conf.UpstreamDNSFileName != "" {
data, err := os.ReadFile(s.conf.UpstreamDNSFileName)
if err != nil {
return fmt.Errorf("reading upstream from file: %w", err)
}
upstreams = stringutil.SplitTrimmed(string(data), "\n")
log.Debug("dns: using %d upstream servers from file %s", len(upstreams), s.conf.UpstreamDNSFileName)
} else {
upstreams = s.conf.UpstreamDNS
}
httpVersions := UpstreamHTTPVersions(s.conf.UseHTTP3Upstreams)
upstreams = stringutil.FilterOut(upstreams, IsCommentOrEmpty)
upstreamConfig, err := proxy.ParseUpstreamsConfig(
upstreams,
&upstream.Options{
Bootstrap: s.conf.BootstrapDNS,
Timeout: s.conf.UpstreamTimeout,
HTTPVersions: httpVersions,
},
)
if err != nil {
return fmt.Errorf("parsing upstream config: %w", err)
}
if len(upstreamConfig.Upstreams) == 0 {
log.Info("warning: no default upstream servers specified, using %v", defaultDNS)
var uc *proxy.UpstreamConfig
uc, err = proxy.ParseUpstreamsConfig(
defaultDNS,
&upstream.Options{
Bootstrap: s.conf.BootstrapDNS,
Timeout: s.conf.UpstreamTimeout,
HTTPVersions: httpVersions,
},
)
if err != nil {
return fmt.Errorf("parsing default upstreams: %w", err)
}
upstreamConfig.Upstreams = uc.Upstreams
}
s.conf.UpstreamConfig = upstreamConfig
return nil
}
// setProxyUpstreamMode sets the upstream mode and related settings in conf
// based on provided parameters.
func setProxyUpstreamMode(
conf *proxy.Config,
allServers bool,
fastestAddr bool,
fastestTimeout time.Duration,
) {
if allServers {
conf.UpstreamMode = proxy.UModeParallel
} else if fastestAddr {
conf.UpstreamMode = proxy.UModeFastestAddr
conf.FastestPingTimeout = fastestTimeout
} else {
conf.UpstreamMode = proxy.UModeLoadBalance
}
}
// prepareIpsetListSettings reads and prepares the ipset configuration either
// from a file or from the data in the configuration file.
func (s *Server) prepareIpsetListSettings() (err error) {
fn := s.conf.IpsetListFileName
if fn == "" {
return s.ipset.init(s.conf.IpsetList)
}
data, err := os.ReadFile(fn)
if err != nil {
return err
}
ipsets := stringutil.SplitTrimmed(string(data), "\n")
log.Debug("dns: using %d ipset rules from file %q", len(ipsets), fn)
return s.ipset.init(ipsets)
}
// prepareTLS - prepares TLS configuration for the DNS proxy
func (s *Server) prepareTLS(proxyConfig *proxy.Config) (err error) {
if len(s.conf.CertificateChainData) == 0 || len(s.conf.PrivateKeyData) == 0 {
return nil
}
if s.conf.TLSListenAddrs == nil && s.conf.QUICListenAddrs == nil {
return nil
}
proxyConfig.TLSListenAddr = aghalg.CoalesceSlice(
s.conf.TLSListenAddrs,
proxyConfig.TLSListenAddr,
)
proxyConfig.QUICListenAddr = aghalg.CoalesceSlice(
s.conf.QUICListenAddrs,
proxyConfig.QUICListenAddr,
)
s.conf.cert, err = tls.X509KeyPair(s.conf.CertificateChainData, s.conf.PrivateKeyData)
if err != nil {
return fmt.Errorf("failed to parse TLS keypair: %w", err)
}
cert, err := x509.ParseCertificate(s.conf.cert.Certificate[0])
if err != nil {
return fmt.Errorf("x509.ParseCertificate(): %w", err)
}
s.conf.hasIPAddrs = aghtls.CertificateHasIP(cert)
if s.conf.StrictSNICheck {
if len(cert.DNSNames) != 0 {
s.conf.dnsNames = cert.DNSNames
log.Debug("dnsforward: using certificate's SAN as DNS names: %v", cert.DNSNames)
slices.Sort(s.conf.dnsNames)
} else {
s.conf.dnsNames = append(s.conf.dnsNames, cert.Subject.CommonName)
log.Debug("dnsforward: using certificate's CN as DNS name: %s", cert.Subject.CommonName)
}
}
proxyConfig.TLSConfig = &tls.Config{
GetCertificate: s.onGetCertificate,
CipherSuites: s.conf.TLSCiphers,
MinVersion: tls.VersionTLS12,
}
return nil
}
// isWildcard returns true if host is a wildcard hostname.
func isWildcard(host string) (ok bool) {
return len(host) >= 2 && host[0] == '*' && host[1] == '.'
}
// matchesDomainWildcard returns true if host matches the domain wildcard
// pattern pat.
func matchesDomainWildcard(host, pat string) (ok bool) {
return isWildcard(pat) && strings.HasSuffix(host, pat[1:])
}
// anyNameMatches returns true if sni, the client's SNI value, matches any of
// the DNS names and patterns from certificate. dnsNames must be sorted.
func anyNameMatches(dnsNames []string, sni string) (ok bool) {
// Check sni is either a valid hostname or a valid IP address.
if netutil.ValidateHostname(sni) != nil && net.ParseIP(sni) == nil {
return false
}
if _, ok = slices.BinarySearch(dnsNames, sni); ok {
return true
}
for _, dn := range dnsNames {
if matchesDomainWildcard(sni, dn) {
return true
}
}
return false
}
// Called by 'tls' package when Client Hello is received
// If the server name (from SNI) supplied by client is incorrect - we terminate the ongoing TLS handshake.
func (s *Server) onGetCertificate(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
if s.conf.StrictSNICheck && !anyNameMatches(s.conf.dnsNames, ch.ServerName) {
log.Info("dns: tls: unknown SNI in Client Hello: %s", ch.ServerName)
return nil, fmt.Errorf("invalid SNI")
}
return &s.conf.cert, nil
}