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Feature: add dhcp type dns client (#1509)

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This commit is contained in:
Kr328
2021-09-06 23:07:34 +08:00
committed by GitHub
parent a2d59d6ef5
commit a5b950a779
26 changed files with 759 additions and 288 deletions
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35
dns/resolver.go
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@ -87,6 +87,11 @@ func (r *Resolver) shouldIPFallback(ip net.IP) bool {
// Exchange a batch of dns request, and it use cache
func (r *Resolver) Exchange(m *D.Msg) (msg *D.Msg, err error) {
return r.ExchangeContext(context.Background(), m)
}
// ExchangeContext a batch of dns request with context.Context, and it use cache
func (r *Resolver) ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
if len(m.Question) == 0 {
return nil, errors.New("should have one question at least")
}
@ -98,17 +103,17 @@ func (r *Resolver) Exchange(m *D.Msg) (msg *D.Msg, err error) {
msg = cache.(*D.Msg).Copy()
if expireTime.Before(now) {
setMsgTTL(msg, uint32(1)) // Continue fetch
go r.exchangeWithoutCache(m)
go r.exchangeWithoutCache(ctx, m)
} else {
setMsgTTL(msg, uint32(time.Until(expireTime).Seconds()))
}
return
}
return r.exchangeWithoutCache(m)
return r.exchangeWithoutCache(ctx, m)
}
// ExchangeWithoutCache a batch of dns request, and it do NOT GET from cache
func (r *Resolver) exchangeWithoutCache(m *D.Msg) (msg *D.Msg, err error) {
func (r *Resolver) exchangeWithoutCache(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
q := m.Question[0]
ret, err, shared := r.group.Do(q.String(), func() (result interface{}, err error) {
@ -124,13 +129,13 @@ func (r *Resolver) exchangeWithoutCache(m *D.Msg) (msg *D.Msg, err error) {
isIPReq := isIPRequest(q)
if isIPReq {
return r.ipExchange(m)
return r.ipExchange(ctx, m)
}
if matched := r.matchPolicy(m); len(matched) != 0 {
return r.batchExchange(matched, m)
return r.batchExchange(ctx, matched, m)
}
return r.batchExchange(r.main, m)
return r.batchExchange(ctx, r.main, m)
})
if err == nil {
@ -143,8 +148,8 @@ func (r *Resolver) exchangeWithoutCache(m *D.Msg) (msg *D.Msg, err error) {
return
}
func (r *Resolver) batchExchange(clients []dnsClient, m *D.Msg) (msg *D.Msg, err error) {
fast, ctx := picker.WithTimeout(context.Background(), resolver.DefaultDNSTimeout)
func (r *Resolver) batchExchange(ctx context.Context, clients []dnsClient, m *D.Msg) (msg *D.Msg, err error) {
fast, ctx := picker.WithTimeout(ctx, resolver.DefaultDNSTimeout)
for _, client := range clients {
r := client
fast.Go(func() (interface{}, error) {
@ -209,21 +214,21 @@ func (r *Resolver) shouldOnlyQueryFallback(m *D.Msg) bool {
return false
}
func (r *Resolver) ipExchange(m *D.Msg) (msg *D.Msg, err error) {
func (r *Resolver) ipExchange(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
if matched := r.matchPolicy(m); len(matched) != 0 {
res := <-r.asyncExchange(matched, m)
res := <-r.asyncExchange(ctx, matched, m)
return res.Msg, res.Error
}
onlyFallback := r.shouldOnlyQueryFallback(m)
if onlyFallback {
res := <-r.asyncExchange(r.fallback, m)
res := <-r.asyncExchange(ctx, r.fallback, m)
return res.Msg, res.Error
}
msgCh := r.asyncExchange(r.main, m)
msgCh := r.asyncExchange(ctx, r.main, m)
if r.fallback == nil { // directly return if no fallback servers are available
res := <-msgCh
@ -231,7 +236,7 @@ func (r *Resolver) ipExchange(m *D.Msg) (msg *D.Msg, err error) {
return
}
fallbackMsg := r.asyncExchange(r.fallback, m)
fallbackMsg := r.asyncExchange(ctx, r.fallback, m)
res := <-msgCh
if res.Error == nil {
if ips := msgToIP(res.Msg); len(ips) != 0 {
@ -287,10 +292,10 @@ func (r *Resolver) msgToDomain(msg *D.Msg) string {
return ""
}
func (r *Resolver) asyncExchange(client []dnsClient, msg *D.Msg) <-chan *result {
func (r *Resolver) asyncExchange(ctx context.Context, client []dnsClient, msg *D.Msg) <-chan *result {
ch := make(chan *result, 1)
go func() {
res, err := r.batchExchange(client, msg)
res, err := r.batchExchange(ctx, client, msg)
ch <- &result{Msg: res, Error: err}
}()
return ch