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- package dns
- import (
- "context"
- "fmt"
- "net"
- "strings"
- "sync"
- "time"
- "github.com/metacubex/mihomo/component/resolver"
- "github.com/metacubex/mihomo/log"
- D "github.com/miekg/dns"
- "golang.org/x/exp/slices"
- )
- const (
- SystemDnsFlushTime = 5 * time.Minute
- SystemDnsDeleteTimes = 12 // 12*5 = 60min
- )
- type systemDnsClient struct {
- disableTimes uint32
- dnsClient
- }
- type systemClient struct {
- mu sync.Mutex
- dnsClients map[string]*systemDnsClient
- lastFlush time.Time
- }
- func (c *systemClient) getDnsClients() ([]dnsClient, error) {
- c.mu.Lock()
- defer c.mu.Unlock()
- var err error
- if time.Since(c.lastFlush) > SystemDnsFlushTime {
- var nameservers []string
- if nameservers, err = dnsReadConfig(); err == nil {
- log.Debugln("[DNS] system dns update to %s", nameservers)
- for _, addr := range nameservers {
- if resolver.IsSystemDnsBlacklisted(addr) {
- continue
- }
- if _, ok := c.dnsClients[addr]; !ok {
- clients := transform(
- []NameServer{{
- Addr: net.JoinHostPort(addr, "53"),
- Net: "udp",
- }},
- nil,
- )
- if len(clients) > 0 {
- c.dnsClients[addr] = &systemDnsClient{
- disableTimes: 0,
- dnsClient: clients[0],
- }
- }
- }
- }
- available := 0
- for nameserver, sdc := range c.dnsClients {
- if slices.Contains(nameservers, nameserver) {
- sdc.disableTimes = 0 // enable
- available++
- } else {
- if sdc.disableTimes > SystemDnsDeleteTimes {
- delete(c.dnsClients, nameserver) // drop too old dnsClient
- } else {
- sdc.disableTimes++
- }
- }
- }
- if available > 0 {
- c.lastFlush = time.Now()
- }
- }
- }
- dnsClients := make([]dnsClient, 0, len(c.dnsClients))
- for _, sdc := range c.dnsClients {
- if sdc.disableTimes == 0 {
- dnsClients = append(dnsClients, sdc.dnsClient)
- }
- }
- if len(dnsClients) > 0 {
- return dnsClients, nil
- }
- return nil, err
- }
- func (c *systemClient) ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
- dnsClients, err := c.getDnsClients()
- if err != nil {
- return
- }
- msg, _, err = batchExchange(ctx, dnsClients, m)
- return
- }
- // Address implements dnsClient
- func (c *systemClient) Address() string {
- dnsClients, _ := c.getDnsClients()
- addrs := make([]string, 0, len(dnsClients))
- for _, c := range dnsClients {
- addrs = append(addrs, c.Address())
- }
- return fmt.Sprintf("system(%s)", strings.Join(addrs, ","))
- }
- var _ dnsClient = (*systemClient)(nil)
- func newSystemClient() *systemClient {
- return &systemClient{
- dnsClients: map[string]*systemDnsClient{},
- }
- }
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