97 lines
2.5 KiB
Go
97 lines
2.5 KiB
Go
package filtering
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import (
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"github.com/AdguardTeam/urlfilter"
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"github.com/AdguardTeam/urlfilter/rules"
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"github.com/miekg/dns"
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)
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// DNSRewriteResult is the result of application of $dnsrewrite rules.
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type DNSRewriteResult struct {
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Response DNSRewriteResultResponse `json:",omitempty"`
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RCode rules.RCode `json:",omitempty"`
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}
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// DNSRewriteResultResponse is the collection of DNS response records
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// the server returns.
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type DNSRewriteResultResponse map[rules.RRType][]rules.RRValue
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// processDNSRewrites processes DNS rewrite rules in dnsr. It returns an empty
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// result if dnsr is empty. Otherwise, the result will have either CanonName or
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// DNSRewriteResult set. dnsr is expected to be non-empty.
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func (d *DNSFilter) processDNSRewrites(dnsr []*rules.NetworkRule) (res Result) {
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var rules []*ResultRule
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dnsrr := &DNSRewriteResult{
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Response: DNSRewriteResultResponse{},
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}
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for _, nr := range dnsr {
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dr := nr.DNSRewrite
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if dr.NewCNAME != "" {
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// NewCNAME rules have a higher priority than other rules.
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rules = []*ResultRule{{
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FilterListID: nr.GetFilterListID(),
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Text: nr.RuleText,
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}}
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return Result{
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Rules: rules,
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Reason: RewrittenRule,
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CanonName: dr.NewCNAME,
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}
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}
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switch dr.RCode {
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case dns.RcodeSuccess:
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dnsrr.RCode = dr.RCode
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dnsrr.Response[dr.RRType] = append(dnsrr.Response[dr.RRType], dr.Value)
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rules = append(rules, &ResultRule{
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FilterListID: nr.GetFilterListID(),
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Text: nr.RuleText,
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})
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default:
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// RcodeRefused and other such codes have higher priority. Return
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// immediately.
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rules = []*ResultRule{{
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FilterListID: nr.GetFilterListID(),
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Text: nr.RuleText,
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}}
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dnsrr = &DNSRewriteResult{
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RCode: dr.RCode,
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}
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return Result{
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DNSRewriteResult: dnsrr,
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Rules: rules,
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Reason: RewrittenRule,
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}
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}
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}
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return Result{
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DNSRewriteResult: dnsrr,
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Rules: rules,
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Reason: RewrittenRule,
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}
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}
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// processDNSResultRewrites returns an empty Result if there are no dnsrewrite
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// rules in dnsres. Otherwise, it returns the processed Result.
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func (d *DNSFilter) processDNSResultRewrites(
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dnsres *urlfilter.DNSResult,
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host string,
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) (dnsRWRes Result) {
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dnsr := dnsres.DNSRewrites()
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if len(dnsr) == 0 {
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return Result{}
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}
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res := d.processDNSRewrites(dnsr)
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if res.Reason == RewrittenRule && res.CanonName == host {
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// A rewrite of a host to itself. Go on and try matching other things.
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return Result{}
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}
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return res
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}
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