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