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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,283 @@ | ||
| /* | ||
| * Copyright (C) 2020-2022, IrineSistiana | ||
| * | ||
| * This file is part of mosdns. | ||
| * | ||
| * mosdns is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
| * the Free Software Foundation, either version 3 of the License, or | ||
| * (at your option) any later version. | ||
| * | ||
| * mosdns is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <https://www.gnu.org/licenses/>. | ||
| */ | ||
|
|
||
| package doq | ||
|
|
||
| import ( | ||
| "context" | ||
| "crypto/rand" | ||
| "crypto/tls" | ||
| "errors" | ||
| "net" | ||
| "sync" | ||
| "sync/atomic" | ||
| "time" | ||
|
|
||
| "github.com/IrineSistiana/mosdns/v5/pkg/dnsutils" | ||
| "github.com/IrineSistiana/mosdns/v5/pkg/pool" | ||
| "github.com/miekg/dns" | ||
| "github.com/quic-go/quic-go" | ||
| ) | ||
|
|
||
| const ( | ||
| defaultDoQTimeout = time.Second * 5 | ||
| dialTimeout = time.Second * 3 | ||
| connectionLostThreshold = time.Second * 5 | ||
| ) | ||
|
|
||
| var ( | ||
| doqAlpn = []string{"doq"} | ||
| ) | ||
|
|
||
| type Upstream struct { | ||
| t *quic.Transport | ||
| addr string | ||
| tlsConfig *tls.Config | ||
| quicConfig *quic.Config | ||
|
|
||
| cm sync.Mutex | ||
| lc *lazyConn | ||
| } | ||
|
|
||
| // tlsConfig cannot be nil, it should have Servername or InsecureSkipVerify. | ||
| func NewUpstream(addr string, lc *net.UDPConn, tlsConfig *tls.Config, quicConfig *quic.Config) (*Upstream, error) { | ||
| srk, err := initSrk() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| if tlsConfig == nil { | ||
| return nil, errors.New("nil tls config") | ||
| } | ||
|
|
||
| tlsConfig = tlsConfig.Clone() | ||
| tlsConfig.NextProtos = doqAlpn | ||
|
|
||
| return &Upstream{ | ||
| t: &quic.Transport{ | ||
| Conn: lc, | ||
| StatelessResetKey: (*quic.StatelessResetKey)(srk), | ||
| }, | ||
| addr: addr, | ||
| tlsConfig: tlsConfig, | ||
| quicConfig: quicConfig, | ||
| }, nil | ||
| } | ||
|
|
||
| func initSrk() (*[32]byte, error) { | ||
| var b [32]byte | ||
| _, err := rand.Read(b[:]) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return &b, nil | ||
| } | ||
|
|
||
| func (u *Upstream) Close() error { | ||
| return u.t.Close() | ||
| } | ||
|
|
||
| func (u *Upstream) newStream(ctx context.Context) (quic.Stream, *lazyConn, error) { | ||
| var lc *lazyConn | ||
| u.cm.Lock() | ||
| if u.lc == nil { // First dial. | ||
| u.lc = u.asyncDialConn() | ||
| } else { | ||
| select { | ||
| case <-u.lc.dialFinished: | ||
| if u.lc.err != nil { // previous dial failed | ||
| u.lc = u.asyncDialConn() | ||
| } else { | ||
| err := u.lc.c.Context().Err() | ||
| if err != nil { // previous connection is dead or closed | ||
| u.lc = u.asyncDialConn() | ||
| } | ||
| // previous connection looks good | ||
| } | ||
| default: | ||
| // still dialing | ||
| } | ||
| } | ||
| lc = u.lc | ||
| u.cm.Unlock() | ||
|
|
||
| select { | ||
| case <-lc.dialFinished: | ||
| if lc.c == nil { | ||
| return nil, nil, lc.err | ||
| } | ||
| s, err := lc.c.OpenStream() | ||
| if err != nil { | ||
| lc.queryFailedAndCloseIfConnLost(time.Now()) | ||
| return nil, nil, err | ||
| } | ||
| return s, lc, nil | ||
| case <-ctx.Done(): | ||
| return nil, nil, ctx.Err() | ||
| } | ||
| } | ||
|
|
||
| type lazyConn struct { | ||
| cancelDial func() | ||
|
|
||
| m sync.Mutex | ||
| closed bool | ||
| dialFinished chan struct{} | ||
| c quic.Connection | ||
| err error | ||
|
|
||
| latestRecvMs atomic.Int64 | ||
| } | ||
|
|
||
| func (u *Upstream) asyncDialConn() *lazyConn { | ||
| ctx, cancel := context.WithTimeout(context.Background(), dialTimeout) | ||
| lc := &lazyConn{ | ||
| cancelDial: cancel, | ||
| dialFinished: make(chan struct{}), | ||
| } | ||
|
|
||
| go func() { | ||
| defer cancel() | ||
|
|
||
| ua, err := net.ResolveUDPAddr("udp", u.addr) // TODO: Support bootstrap. | ||
| if err != nil { | ||
| lc.err = err | ||
| return | ||
| } | ||
|
|
||
| c, err := u.t.Dial(ctx, ua, u.tlsConfig, u.quicConfig) | ||
|
|
||
| var closeC bool | ||
| lc.m.Lock() | ||
| if lc.closed { | ||
| closeC = true // lc was closed, nothing to do | ||
| } else { | ||
| if err != nil { | ||
| lc.err = err | ||
| } else { | ||
| lc.c = c | ||
| lc.saveLatestRespRecvTime(time.Now()) | ||
| } | ||
| close(lc.dialFinished) | ||
| } | ||
| lc.m.Unlock() | ||
|
|
||
| if closeC && c != nil { // lc was closed while dialing. | ||
| c.CloseWithError(0, "") | ||
| } | ||
| }() | ||
| return lc | ||
| } | ||
|
|
||
| func (lc *lazyConn) close() { | ||
| lc.m.Lock() | ||
| defer lc.m.Unlock() | ||
|
|
||
| if lc.closed { | ||
| return | ||
| } | ||
| lc.closed = true | ||
|
|
||
| select { | ||
| case <-lc.dialFinished: | ||
| if lc.c != nil { | ||
| lc.c.CloseWithError(0, "") | ||
| } | ||
| default: | ||
| lc.cancelDial() | ||
| lc.err = net.ErrClosed | ||
| close(lc.dialFinished) | ||
| } | ||
| } | ||
|
|
||
| func (lc *lazyConn) saveLatestRespRecvTime(t time.Time) { | ||
| lc.latestRecvMs.Store(t.UnixMilli()) | ||
| } | ||
|
|
||
| func (lc *lazyConn) latestRespRecvTime() time.Time { | ||
| return time.UnixMilli(lc.latestRecvMs.Load()) | ||
| } | ||
|
|
||
| func (lc *lazyConn) queryFailedAndCloseIfConnLost(t time.Time) { | ||
| // No msg received for a quit long time. This connection may be lost. | ||
| if time.Since(lc.latestRespRecvTime()) > connectionLostThreshold { | ||
| lc.close() | ||
| } | ||
| } | ||
|
|
||
| func (u *Upstream) ExchangeContext(ctx context.Context, q *dns.Msg) (*dns.Msg, error) { | ||
| payload, err := pool.PackTCPBuffer(q) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| // 4.2.1. DNS Message IDs | ||
| // When sending queries over a QUIC connection, the DNS Message ID MUST | ||
| // be set to 0. The stream mapping for DoQ allows for unambiguous | ||
| // correlation of queries and responses, so the Message ID field is not | ||
| // required. | ||
| (*payload)[2], (*payload)[3] = 0, 0 | ||
|
|
||
| s, lc, err := u.newStream(ctx) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| type res struct { | ||
| resp *dns.Msg | ||
| err error | ||
| } | ||
| rc := make(chan res, 1) | ||
| go func() { | ||
| defer pool.ReleaseBuf(payload) | ||
| defer s.Close() | ||
| r, err := u.exchange(s, *payload) | ||
| rc <- res{resp: r, err: err} | ||
| if err != nil { | ||
| lc.queryFailedAndCloseIfConnLost(time.Now()) | ||
| } else { | ||
| lc.saveLatestRespRecvTime(time.Now()) | ||
| } | ||
| }() | ||
|
|
||
| select { | ||
| case <-ctx.Done(): | ||
| return nil, context.Cause(ctx) | ||
| case r := <-rc: | ||
| resp := r.resp | ||
| err := r.err | ||
| if resp != nil { | ||
| resp.Id = q.Id | ||
| } | ||
| return resp, err | ||
| } | ||
| } | ||
|
|
||
| func (u *Upstream) exchange(s quic.Stream, payload []byte) (*dns.Msg, error) { | ||
| s.SetDeadline(time.Now().Add(defaultDoQTimeout)) | ||
|
|
||
| _, err := s.Write(payload) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| resp, _, err := dnsutils.ReadMsgFromTCP(s) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return resp, nil | ||
| } |
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