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dns.go
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dns.go
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// +build !confonly
// Package dns is an implementation of core.DNS feature.
package dns
//go:generate go run github.com/v2fly/v2ray-core/v4/common/errors/errorgen
import (
"context"
"fmt"
"strings"
"sync"
"github.com/v2fly/v2ray-core/v4/app/router"
"github.com/v2fly/v2ray-core/v4/common"
"github.com/v2fly/v2ray-core/v4/common/errors"
"github.com/v2fly/v2ray-core/v4/common/net"
"github.com/v2fly/v2ray-core/v4/common/session"
"github.com/v2fly/v2ray-core/v4/common/strmatcher"
"github.com/v2fly/v2ray-core/v4/features"
"github.com/v2fly/v2ray-core/v4/features/dns"
)
// DNS is a DNS rely server.
type DNS struct {
sync.Mutex
tag string
disableCache bool
hosts *StaticHosts
clients []*Client
ctx context.Context
domainMatcher strmatcher.IndexMatcher
matcherInfos []DomainMatcherInfo
}
// DomainMatcherInfo contains information attached to index returned by Server.domainMatcher
type DomainMatcherInfo struct {
clientIdx uint16
domainRuleIdx uint16
}
// New creates a new DNS server with given configuration.
func New(ctx context.Context, config *Config) (*DNS, error) {
var tag string
if len(config.Tag) > 0 {
tag = config.Tag
} else {
tag = generateRandomTag()
}
var clientIP net.IP
switch len(config.ClientIp) {
case 0, net.IPv4len, net.IPv6len:
clientIP = net.IP(config.ClientIp)
default:
return nil, newError("unexpected client IP length ", len(config.ClientIp))
}
hosts, err := NewStaticHosts(config.StaticHosts, config.Hosts)
if err != nil {
return nil, newError("failed to create hosts").Base(err)
}
clients := []*Client{}
domainRuleCount := 0
for _, ns := range config.NameServer {
domainRuleCount += len(ns.PrioritizedDomain)
}
// MatcherInfos is ensured to cover the maximum index domainMatcher could return, where matcher's index starts from 1
matcherInfos := make([]DomainMatcherInfo, domainRuleCount+1)
domainMatcher := &strmatcher.MatcherGroup{}
geoipContainer := router.GeoIPMatcherContainer{}
for _, endpoint := range config.NameServers {
features.PrintDeprecatedFeatureWarning("simple DNS server")
client, err := NewSimpleClient(ctx, endpoint, clientIP)
if err != nil {
return nil, newError("failed to create client").Base(err)
}
clients = append(clients, client)
}
for _, ns := range config.NameServer {
clientIdx := len(clients)
updateDomain := func(domainRule strmatcher.Matcher, originalRuleIdx int, matcherInfos []DomainMatcherInfo) error {
midx := domainMatcher.Add(domainRule)
matcherInfos[midx] = DomainMatcherInfo{
clientIdx: uint16(clientIdx),
domainRuleIdx: uint16(originalRuleIdx),
}
return nil
}
myClientIP := clientIP
switch len(ns.ClientIp) {
case net.IPv4len, net.IPv6len:
myClientIP = net.IP(ns.ClientIp)
}
client, err := NewClient(ctx, ns, myClientIP, geoipContainer, &matcherInfos, updateDomain)
if err != nil {
return nil, newError("failed to create client").Base(err)
}
clients = append(clients, client)
}
// If there is no DNS client in config, add a `localhost` DNS client
if len(clients) == 0 {
clients = append(clients, NewLocalDNSClient())
}
return &DNS{
tag: tag,
hosts: hosts,
clients: clients,
ctx: ctx,
domainMatcher: domainMatcher,
matcherInfos: matcherInfos,
disableCache: config.DisableCache,
}, nil
}
// Type implements common.HasType.
func (*DNS) Type() interface{} {
return dns.ClientType()
}
// Start implements common.Runnable.
func (s *DNS) Start() error {
return nil
}
// Close implements common.Closable.
func (s *DNS) Close() error {
return nil
}
// IsOwnLink implements proxy.dns.ownLinkVerifier
func (s *DNS) IsOwnLink(ctx context.Context) bool {
inbound := session.InboundFromContext(ctx)
return inbound != nil && inbound.Tag == s.tag
}
// LookupIP implements dns.Client.
func (s *DNS) LookupIP(domain string, option dns.IPOption) ([]net.IP, error) {
if domain == "" {
return nil, newError("empty domain name")
}
// Normalize the FQDN form query
if strings.HasSuffix(domain, ".") {
domain = domain[:len(domain)-1]
}
// Static host lookup
switch addrs := s.hosts.Lookup(domain, option); {
case addrs == nil: // Domain not recorded in static host
break
case len(addrs) == 0: // Domain recorded, but no valid IP returned (e.g. IPv4 address with only IPv6 enabled)
return nil, dns.ErrEmptyResponse
case len(addrs) == 1 && addrs[0].Family().IsDomain(): // Domain replacement
newError("domain replaced: ", domain, " -> ", addrs[0].Domain()).WriteToLog()
domain = addrs[0].Domain()
default: // Successfully found ip records in static host
newError("returning ", len(addrs), " IPs for domain ", domain).WriteToLog()
return toNetIP(addrs)
}
// Name servers lookup
errs := []error{}
ctx := session.ContextWithInbound(s.ctx, &session.Inbound{Tag: s.tag})
for _, client := range s.sortClients(domain) {
if !option.FakeEnable && strings.EqualFold(client.Name(), "FakeDNS") {
newError("skip DNS resolution for domain ", domain, " at server ", client.Name()).AtDebug().WriteToLog()
continue
}
ips, err := client.QueryIP(ctx, domain, option, s.disableCache)
if len(ips) > 0 {
return ips, nil
}
if err != nil {
newError("failed to lookup ip for domain ", domain, " at server ", client.Name()).Base(err).WriteToLog()
errs = append(errs, err)
}
if err != context.Canceled && err != context.DeadlineExceeded && err != errExpectedIPNonMatch {
return nil, err
}
}
return nil, newError("returning nil for domain ", domain).Base(errors.Combine(errs...))
}
func (s *DNS) sortClients(domain string) []*Client {
clients := make([]*Client, 0, len(s.clients))
clientUsed := make([]bool, len(s.clients))
clientNames := make([]string, 0, len(s.clients))
domainRules := []string{}
// Priority domain matching
for _, match := range s.domainMatcher.Match(domain) {
info := s.matcherInfos[match]
client := s.clients[info.clientIdx]
domainRule := client.domains[info.domainRuleIdx]
domainRules = append(domainRules, fmt.Sprintf("%s(DNS idx:%d)", domainRule, info.clientIdx))
if clientUsed[info.clientIdx] {
continue
}
clientUsed[info.clientIdx] = true
clients = append(clients, client)
clientNames = append(clientNames, client.Name())
}
// Default round-robin query
for idx, client := range s.clients {
if clientUsed[idx] {
continue
}
clientUsed[idx] = true
clients = append(clients, client)
clientNames = append(clientNames, client.Name())
}
if len(domainRules) > 0 {
newError("domain ", domain, " matches following rules: ", domainRules).AtDebug().WriteToLog()
}
if len(clientNames) > 0 {
newError("domain ", domain, " will use DNS in order: ", clientNames).AtDebug().WriteToLog()
}
return clients
}
func init() {
common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
return New(ctx, config.(*Config))
}))
}