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dns.go
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dns.go
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/*
* SPDX-License-Identifier: AGPL-3.0-only
* Copyright (c) 2022-2024, daeuniverse Organization <dae@v2raya.org>
*/
package dns
import (
"fmt"
"net/netip"
"net/url"
"sync"
"github.com/daeuniverse/dae/common"
"github.com/daeuniverse/dae/common/assets"
"github.com/daeuniverse/dae/common/consts"
"github.com/daeuniverse/dae/component/routing"
"github.com/daeuniverse/dae/config"
dnsmessage "github.com/miekg/dns"
"github.com/sirupsen/logrus"
)
var ErrBadUpstreamFormat = fmt.Errorf("bad upstream format")
type Dns struct {
log *logrus.Logger
upstream []*UpstreamResolver
upstream2IndexMu sync.Mutex
upstream2Index map[*Upstream]int
reqMatcher *RequestMatcher
respMatcher *ResponseMatcher
}
type NewOption struct {
Logger *logrus.Logger
LocationFinder *assets.LocationFinder
UpstreamReadyCallback func(dnsUpstream *Upstream) (err error)
UpstreamResolverNetwork string
}
func New(dns *config.Dns, opt *NewOption) (s *Dns, err error) {
s = &Dns{
log: opt.Logger,
upstream2Index: map[*Upstream]int{
nil: int(consts.DnsRequestOutboundIndex_AsIs),
},
}
// Parse upstream.
upstreamName2Id := map[string]uint8{}
for i, upstreamRaw := range dns.Upstream {
if i >= int(consts.DnsRequestOutboundIndex_UserDefinedMax) ||
i >= int(consts.DnsResponseOutboundIndex_UserDefinedMax) {
return nil, fmt.Errorf("too many upstreams")
}
tag, link := common.GetTagFromLinkLikePlaintext(string(upstreamRaw))
if tag == "" {
return nil, fmt.Errorf("%w: '%v' has no tag", ErrBadUpstreamFormat, upstreamRaw)
}
var u *url.URL
u, err = url.Parse(link)
if err != nil {
return nil, fmt.Errorf("%w: %v", ErrBadUpstreamFormat, err)
}
r := &UpstreamResolver{
Raw: u,
Network: opt.UpstreamResolverNetwork,
FinishInitCallback: func(i int) func(raw *url.URL, upstream *Upstream) (err error) {
return func(raw *url.URL, upstream *Upstream) (err error) {
if opt != nil && opt.UpstreamReadyCallback != nil {
if err = opt.UpstreamReadyCallback(upstream); err != nil {
return err
}
}
s.upstream2IndexMu.Lock()
s.upstream2Index[upstream] = i
s.upstream2IndexMu.Unlock()
return nil
}
}(i),
mu: sync.Mutex{},
upstream: nil,
init: false,
}
upstreamName2Id[tag] = uint8(len(s.upstream))
s.upstream = append(s.upstream, r)
}
// Optimize routings.
if dns.Routing.Request.Rules, err = routing.ApplyRulesOptimizers(dns.Routing.Request.Rules,
&routing.DatReaderOptimizer{Logger: opt.Logger, LocationFinder: opt.LocationFinder},
&routing.MergeAndSortRulesOptimizer{},
&routing.DeduplicateParamsOptimizer{},
); err != nil {
return nil, err
}
if dns.Routing.Response.Rules, err = routing.ApplyRulesOptimizers(dns.Routing.Response.Rules,
&routing.DatReaderOptimizer{Logger: opt.Logger, LocationFinder: opt.LocationFinder},
&routing.MergeAndSortRulesOptimizer{},
&routing.DeduplicateParamsOptimizer{},
); err != nil {
return nil, err
}
// Parse request routing.
reqMatcherBuilder, err := NewRequestMatcherBuilder(opt.Logger, dns.Routing.Request.Rules, upstreamName2Id, dns.Routing.Request.Fallback)
if err != nil {
return nil, fmt.Errorf("failed to build DNS request routing: %w", err)
}
s.reqMatcher, err = reqMatcherBuilder.Build()
if err != nil {
return nil, fmt.Errorf("failed to build DNS request routing: %w", err)
}
// Parse response routing.
respMatcherBuilder, err := NewResponseMatcherBuilder(opt.Logger, dns.Routing.Response.Rules, upstreamName2Id, dns.Routing.Response.Fallback)
if err != nil {
return nil, fmt.Errorf("failed to build DNS response routing: %w", err)
}
s.respMatcher, err = respMatcherBuilder.Build()
if err != nil {
return nil, fmt.Errorf("failed to build DNS response routing: %w", err)
}
if len(dns.Upstream) == 0 {
// Immediately ready.
go opt.UpstreamReadyCallback(nil)
}
return s, nil
}
func (s *Dns) CheckUpstreamsFormat() error {
for _, upstream := range s.upstream {
_, _, _, err := ParseRawUpstream(upstream.Raw)
if err != nil {
return err
}
}
return nil
}
func (s *Dns) InitUpstreams() {
var wg sync.WaitGroup
for _, upstream := range s.upstream {
wg.Add(1)
go func(upstream *UpstreamResolver) {
_, err := upstream.GetUpstream()
if err != nil {
s.log.WithError(err).Debugln("Dns.GetUpstream")
}
wg.Done()
}(upstream)
}
wg.Wait()
}
func (s *Dns) RequestSelect(qname string, qtype uint16) (upstreamIndex consts.DnsRequestOutboundIndex, upstream *Upstream, err error) {
// Route.
upstreamIndex, err = s.reqMatcher.Match(qname, qtype)
if err != nil {
return 0, nil, err
}
// nil indicates AsIs.
if upstreamIndex == consts.DnsRequestOutboundIndex_AsIs ||
upstreamIndex == consts.DnsRequestOutboundIndex_Reject {
return upstreamIndex, nil, nil
}
if int(upstreamIndex) >= len(s.upstream) {
return 0, nil, fmt.Errorf("bad upstream index: %v not in [0, %v]", upstreamIndex, len(s.upstream)-1)
}
// Get corresponding upstream.
upstream, err = s.upstream[upstreamIndex].GetUpstream()
if err != nil {
return 0, nil, err
}
return upstreamIndex, upstream, nil
}
func (s *Dns) ResponseSelect(msg *dnsmessage.Msg, fromUpstream *Upstream) (upstreamIndex consts.DnsResponseOutboundIndex, upstream *Upstream, err error) {
if !msg.Response {
return 0, nil, fmt.Errorf("DNS response expected but DNS request received")
}
// Prepare routing.
var qname string
var qtype uint16
var ips []netip.Addr
if len(msg.Question) == 0 {
qname = ""
qtype = 0
} else {
q := msg.Question[0]
qname = q.Name
qtype = q.Qtype
for _, ans := range msg.Answer {
var (
ip netip.Addr
ok bool
)
switch body := ans.(type) {
case *dnsmessage.A:
ip, ok = netip.AddrFromSlice(body.A)
case *dnsmessage.AAAA:
ip, ok = netip.AddrFromSlice(body.AAAA)
}
if !ok {
continue
}
ips = append(ips, ip)
}
}
s.upstream2IndexMu.Lock()
from := s.upstream2Index[fromUpstream]
s.upstream2IndexMu.Unlock()
// Route.
upstreamIndex, err = s.respMatcher.Match(qname, qtype, ips, consts.DnsRequestOutboundIndex(from))
if err != nil {
return 0, nil, err
}
// Get corresponding upstream if upstream is neither 'accept' nor 'reject'.
if !upstreamIndex.IsReserved() {
if int(upstreamIndex) >= len(s.upstream) {
return 0, nil, fmt.Errorf("bad upstream index: %v not in [0, %v]", upstreamIndex, len(s.upstream)-1)
}
upstream, err = s.upstream[upstreamIndex].GetUpstream()
if err != nil {
return 0, nil, err
}
} else {
// Assign explicitly to let coder know.
upstream = nil
}
return upstreamIndex, upstream, nil
}