mirror of https://github.com/0xERR0R/blocky.git
115 lines
2.9 KiB
Go
115 lines
2.9 KiB
Go
package resolver
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import (
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"fmt"
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"strings"
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"github.com/0xERR0R/blocky/config"
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"github.com/0xERR0R/blocky/util"
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"github.com/miekg/dns"
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"github.com/sirupsen/logrus"
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)
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// ConditionalUpstreamResolver delegates DNS question to other DNS resolver dependent on domain name in question
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type ConditionalUpstreamResolver struct {
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NextResolver
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mapping map[string]Resolver
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rewrite map[string]string
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}
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// NewConditionalUpstreamResolver returns new resolver instance
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func NewConditionalUpstreamResolver(cfg config.ConditionalUpstreamConfig) ChainedResolver {
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m := make(map[string]Resolver)
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rewrite := make(map[string]string)
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for domain, upstream := range cfg.Mapping.Upstreams {
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upstreams := make(map[string][]config.Upstream)
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upstreams[upstreamDefaultCfgName] = upstream
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m[strings.ToLower(domain)] = NewParallelBestResolver(upstreams)
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}
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for k, v := range cfg.Rewrite {
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rewrite[strings.ToLower(k)] = strings.ToLower(v)
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}
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return &ConditionalUpstreamResolver{mapping: m, rewrite: rewrite}
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}
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// Configuration returns current configuration
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func (r *ConditionalUpstreamResolver) Configuration() (result []string) {
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if len(r.mapping) > 0 {
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for key, val := range r.mapping {
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result = append(result, fmt.Sprintf("%s = \"%s\"", key, val))
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}
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result = append(result, "rewrite:")
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for key, val := range r.rewrite {
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result = append(result, fmt.Sprintf("%s = \"%s\"", key, val))
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}
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} else {
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result = []string{"deactivated"}
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}
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return
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}
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func (r *ConditionalUpstreamResolver) applyRewrite(domain string) string {
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for k, v := range r.rewrite {
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if strings.HasSuffix(domain, "."+k) {
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return strings.TrimSuffix(domain, "."+k) + "." + v
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}
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}
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return domain
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}
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// Resolve uses the conditional resolver to resolve the query
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func (r *ConditionalUpstreamResolver) Resolve(request *Request) (*Response, error) {
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logger := withPrefix(request.Log, "conditional_resolver")
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if len(r.mapping) > 0 {
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question := request.Req.Question[0]
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domainFromQuestion := r.applyRewrite(util.ExtractDomain(question))
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domain := domainFromQuestion
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// try with domain with and without sub-domains
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for len(domain) > 0 {
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r, found := r.mapping[domain]
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if found {
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request.Req.Question[0].Name = dns.Fqdn(domainFromQuestion)
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response, err := r.Resolve(request)
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if err == nil {
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response.Reason = "CONDITIONAL"
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response.RType = CONDITIONAL
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response.Res.Question[0].Name = question.Name
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}
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var answer string
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if response != nil {
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answer = util.AnswerToString(response.Res.Answer)
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}
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logger.WithFields(logrus.Fields{
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"answer": answer,
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"domain": domain,
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"upstream": r,
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}).Debugf("received response from conditional upstream")
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return response, err
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}
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if i := strings.Index(domain, "."); i >= 0 {
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domain = domain[i+1:]
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} else {
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break
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}
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}
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}
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logger.WithField("next_resolver", Name(r.next)).Trace("go to next resolver")
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return r.next.Resolve(request)
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}
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