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feat(dns): add cname_flattening option #3758

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feat(dns): add cname_flattening option #3758

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13 changes: 7 additions & 6 deletions adapter/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,13 @@ type DNSClient interface {
}

type DNSQueryOptions struct {
Transport DNSTransport
Strategy C.DomainStrategy
LookupStrategy C.DomainStrategy
DisableCache bool
RewriteTTL *uint32
ClientSubnet netip.Prefix
Transport DNSTransport
Strategy C.DomainStrategy
LookupStrategy C.DomainStrategy
DisableCache bool
RewriteTTL *uint32
ClientSubnet netip.Prefix
CnameFlattening bool
}

func DNSQueryOptionsFrom(ctx context.Context, options *option.DomainResolveOptions) (*DNSQueryOptions, error) {
Expand Down
65 changes: 34 additions & 31 deletions dns/client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ type Client struct {
cacheLock compatible.Map[dns.Question, chan struct{}]
transportCache freelru.Cache[transportCacheKey, *dns.Msg]
transportCacheLock compatible.Map[dns.Question, chan struct{}]
cnameFlattening bool
}

type ClientOptions struct {
Expand All @@ -53,6 +54,7 @@ type ClientOptions struct {
IndependentCache bool
CacheCapacity uint32
ClientSubnet netip.Prefix
CnameFlattening bool
RDRC func() adapter.RDRCStore
Logger logger.ContextLogger
}
Expand All @@ -64,6 +66,7 @@ func NewClient(options ClientOptions) *Client {
disableExpire: options.DisableExpire,
independentCache: options.IndependentCache,
clientSubnet: options.ClientSubnet,
cnameFlattening: options.CnameFlattening,
initRDRCFunc: options.RDRC,
logger: options.Logger,
}
Expand Down Expand Up @@ -193,41 +196,41 @@ func (c *Client) Exchange(ctx context.Context, transport adapter.DNSTransport, m
return nil, err
}
}
/*if question.Qtype == dns.TypeA || question.Qtype == dns.TypeAAAA {
validResponse := response
loop:
for {
var (
addresses int
queryCNAME string
)
for _, rawRR := range validResponse.Answer {
switch rr := rawRR.(type) {
case *dns.A:
break loop
case *dns.AAAA:
break loop
case *dns.CNAME:
queryCNAME = rr.Target
if c.cnameFlattening || options.CnameFlattening {
if question.Qtype == dns.TypeA || question.Qtype == dns.TypeAAAA {
validResponse := response
loop:
for {
var queryCNAME string
for _, rawRR := range validResponse.Answer {
switch rr := rawRR.(type) {
case *dns.A:
break loop
case *dns.AAAA:
break loop
case *dns.CNAME:
queryCNAME = rr.Target
}
}
if queryCNAME == "" {
break
}
exMessage := *message
exMessage.Question = []dns.Question{{
Name: queryCNAME,
Qtype: question.Qtype,
Qclass: question.Qclass,
}}
validResponse, err = c.Exchange(ctx, transport, &exMessage, options, responseChecker)
if err != nil {
return nil, err
}
}
if queryCNAME == "" {
break
}
exMessage := *message
exMessage.Question = []dns.Question{{
Name: queryCNAME,
Qtype: question.Qtype,
}}
validResponse, err = c.Exchange(ctx, transport, &exMessage, options, responseChecker)
if err != nil {
return nil, err
if validResponse != response {
response.Answer = append(response.Answer, validResponse.Answer...)
}
}
if validResponse != response {
response.Answer = append(response.Answer, validResponse.Answer...)
}
}*/
}
disableCache = disableCache || (response.Rcode != dns.RcodeSuccess && response.Rcode != dns.RcodeNameError)
if responseChecker != nil {
var rejected bool
Expand Down
5 changes: 3 additions & 2 deletions dns/router.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ import (
"github.com/sagernet/sing-box/log"
"github.com/sagernet/sing-box/option"
R "github.com/sagernet/sing-box/route/rule"
"github.com/sagernet/sing-tun"
tun "github.com/sagernet/sing-tun"
"github.com/sagernet/sing/common"
E "github.com/sagernet/sing/common/exceptions"
F "github.com/sagernet/sing/common/format"
Expand Down Expand Up @@ -65,7 +65,8 @@ func NewRouter(ctx context.Context, logFactory log.Factory, options option.DNSOp
}
return cacheFile
},
Logger: router.logger,
CnameFlattening: options.DNSClientOptions.CnameFlattening,
Logger: router.logger,
})
if options.ReverseMapping {
router.dnsReverseMapping = common.Must1(freelru.NewSharded[netip.Addr, string](1024, maphash.NewHasher[netip.Addr]().Hash32))
Expand Down
1 change: 1 addition & 0 deletions option/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,7 @@ type DNSClientOptions struct {
IndependentCache bool `json:"independent_cache,omitempty"`
CacheCapacity uint32 `json:"cache_capacity,omitempty"`
ClientSubnet *badoption.Prefixable `json:"client_subnet,omitempty"`
CnameFlattening bool `json:"cname_flattening,omitempty"`
}

type LegacyDNSFakeIPOptions struct {
Expand Down