117 lines
2.4 KiB
Go
117 lines
2.4 KiB
Go
package resolver
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import (
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"context"
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"crypto/tls"
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"errors"
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"net"
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"net/http"
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"net/netip"
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"strings"
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)
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var errNotRetry = errors.New("not retry")
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type Resolver struct {
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sysAddr, addr string
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network string
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tlsConfig *tls.Config
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httpClient *http.Client
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r *net.Resolver
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}
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func (r *Resolver) LookupNetIP(ctx context.Context, network, host string) ([]netip.Addr, error) {
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ipNetwork := network
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switch network {
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case "tcp", "udp":
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ipNetwork = "ip"
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case "tcp4", "udp4":
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ipNetwork = "ip4"
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case "tcp6", "udp6":
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ipNetwork = "ip6"
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}
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return r.r.LookupNetIP(ctx, ipNetwork, host)
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}
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func New(dns string, dial func(ctx context.Context, network, address string) (net.Conn, error)) *Resolver {
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r := &Resolver{}
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switch {
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case strings.HasPrefix(dns, "tls://"):
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r.addr = withDefaultPort(dns[len("tls://"):], "853")
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host, _, _ := net.SplitHostPort(r.addr)
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r.tlsConfig = &tls.Config{
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ServerName: host,
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}
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r.r = &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, _, address string) (net.Conn, error) {
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if r.sysAddr == "" {
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r.sysAddr = address
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}
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if r.sysAddr != address {
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return nil, errNotRetry
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}
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conn, err := dial(ctx, "tcp", r.addr)
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if err != nil {
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return nil, err
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}
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return tls.Client(conn, r.tlsConfig), nil
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},
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}
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case strings.HasPrefix(dns, "https://"):
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r.httpClient = &http.Client{
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Transport: &http.Transport{
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DialContext: dial,
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},
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}
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r.r = &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, _, address string) (net.Conn, error) {
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if r.sysAddr == "" {
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r.sysAddr = address
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}
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if r.sysAddr != address {
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return nil, errNotRetry
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}
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return newDoHConn(ctx, r.httpClient, dns)
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},
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}
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case dns != "":
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r.addr = dns
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r.network = "udp"
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if strings.HasPrefix(dns, "tcp://") || strings.HasPrefix(dns, "udp://") {
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r.addr = dns[len("tcp://"):]
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r.network = dns[:len("tcp")]
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}
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r.addr = withDefaultPort(r.addr, "53")
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r.r = &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, _, address string) (net.Conn, error) {
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if r.sysAddr == "" {
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r.sysAddr = address
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}
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if r.sysAddr != address {
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return nil, errNotRetry
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}
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return dial(ctx, r.network, r.addr)
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},
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}
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default:
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r.r = &net.Resolver{}
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}
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return r
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}
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func withDefaultPort(addr, port string) string {
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if _, _, err := net.SplitHostPort(addr); err == nil {
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return addr
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}
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return net.JoinHostPort(addr, port)
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}
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