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fixes #362 Co-authored-by: Dimitri Herzog <dimitri.herzog@gmail.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,225 @@ | ||
| package resolver | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "net" | ||
| "os" | ||
| "strings" | ||
| "time" | ||
|
|
||
| "github.com/0xERR0R/blocky/config" | ||
| "github.com/0xERR0R/blocky/model" | ||
| "github.com/0xERR0R/blocky/util" | ||
| "github.com/miekg/dns" | ||
| "github.com/sirupsen/logrus" | ||
| ) | ||
|
|
||
| const ( | ||
| hostsFileResolverLogger = "hosts_file_resolver" | ||
| ) | ||
|
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| type HostsFileResolver struct { | ||
| NextResolver | ||
| HostsFilePath string | ||
| hosts []host | ||
| ttl uint32 | ||
| refreshPeriod time.Duration | ||
| } | ||
|
|
||
| func (r *HostsFileResolver) handleReverseDNS(request *model.Request) *model.Response { | ||
| question := request.Req.Question[0] | ||
| if question.Qtype == dns.TypePTR { | ||
| response := new(dns.Msg) | ||
| response.SetReply(request.Req) | ||
|
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| for _, host := range r.hosts { | ||
| raddr, _ := dns.ReverseAddr(host.IP.String()) | ||
|
|
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| if raddr == question.Name { | ||
| ptr := new(dns.PTR) | ||
| ptr.Ptr = dns.Fqdn(host.Hostname) | ||
| ptr.Hdr = util.CreateHeader(question, r.ttl) | ||
| response.Answer = append(response.Answer, ptr) | ||
|
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| for _, alias := range host.Aliases { | ||
| ptrAlias := new(dns.PTR) | ||
| ptrAlias.Ptr = dns.Fqdn(alias) | ||
| ptrAlias.Hdr = util.CreateHeader(question, r.ttl) | ||
| response.Answer = append(response.Answer, ptrAlias) | ||
| } | ||
|
|
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| return &model.Response{Res: response, RType: model.ResponseTypeHOSTSFILE, Reason: "HOSTS FILE"} | ||
| } | ||
| } | ||
| } | ||
|
|
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| return nil | ||
| } | ||
|
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| func (r *HostsFileResolver) Resolve(request *model.Request) (*model.Response, error) { | ||
| logger := withPrefix(request.Log, hostsFileResolverLogger) | ||
|
|
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| if r.HostsFilePath == "" { | ||
| return r.next.Resolve(request) | ||
| } | ||
|
|
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| reverseResp := r.handleReverseDNS(request) | ||
| if reverseResp != nil { | ||
| return reverseResp, nil | ||
| } | ||
|
|
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| if len(r.hosts) != 0 { | ||
| response := new(dns.Msg) | ||
| response.SetReply(request.Req) | ||
|
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| question := request.Req.Question[0] | ||
| domain := util.ExtractDomain(question) | ||
|
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| for _, host := range r.hosts { | ||
| if host.Hostname == domain { | ||
| if isSupportedType(host.IP, question) { | ||
| rr, _ := util.CreateAnswerFromQuestion(question, host.IP, r.ttl) | ||
| response.Answer = append(response.Answer, rr) | ||
| } | ||
| } | ||
|
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||
| for _, alias := range host.Aliases { | ||
| if alias == domain { | ||
| if isSupportedType(host.IP, question) { | ||
| rr, _ := util.CreateAnswerFromQuestion(question, host.IP, r.ttl) | ||
| response.Answer = append(response.Answer, rr) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
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| if len(response.Answer) > 0 { | ||
| logger.WithFields(logrus.Fields{ | ||
| "answer": util.AnswerToString(response.Answer), | ||
| "domain": domain, | ||
| }).Debugf("returning hosts file entry") | ||
|
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| return &model.Response{Res: response, RType: model.ResponseTypeHOSTSFILE, Reason: "HOSTS FILE"}, nil | ||
| } | ||
| } | ||
|
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| logger.WithField("resolver", Name(r.next)).Trace("go to next resolver") | ||
|
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| return r.next.Resolve(request) | ||
| } | ||
|
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| func (r *HostsFileResolver) Configuration() (result []string) { | ||
| if r.HostsFilePath != "" && len(r.hosts) != 0 { | ||
| result = append(result, fmt.Sprintf("hosts file path: %s", r.HostsFilePath)) | ||
| result = append(result, fmt.Sprintf("hosts TTL: %d", r.ttl)) | ||
| result = append(result, fmt.Sprintf("hosts refresh period: %s", r.refreshPeriod.String())) | ||
| } else { | ||
| result = []string{"deactivated"} | ||
| } | ||
|
|
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| return | ||
| } | ||
|
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| func NewHostsFileResolver(cfg config.HostsFileConfig) ChainedResolver { | ||
| r := HostsFileResolver{ | ||
| HostsFilePath: cfg.Filepath, | ||
| ttl: uint32(time.Duration(cfg.HostsTTL).Seconds()), | ||
| refreshPeriod: time.Duration(cfg.RefreshPeriod), | ||
| } | ||
|
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| err := r.parseHostsFile() | ||
|
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| if err != nil { | ||
| logger := logger(hostsFileResolverLogger) | ||
| logger.Warnf("cannot parse hosts file: %s, hosts file resolving is disabled", r.HostsFilePath) | ||
| r.HostsFilePath = "" | ||
| } else { | ||
| go r.periodicUpdate() | ||
| } | ||
|
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| return &r | ||
| } | ||
|
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| type host struct { | ||
| IP net.IP | ||
| Hostname string | ||
| Aliases []string | ||
| } | ||
|
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| func (r *HostsFileResolver) parseHostsFile() error { | ||
| if r.HostsFilePath == "" { | ||
| return nil | ||
| } | ||
|
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| buf, err := os.ReadFile(r.HostsFilePath) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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| newHosts := make([]host, 0) | ||
|
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| for _, line := range strings.Split(string(buf), "\n") { | ||
| trimmed := strings.TrimSpace(line) | ||
|
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| if len(trimmed) == 0 || trimmed[0] == '#' { | ||
| // Skip empty and commented lines | ||
| continue | ||
| } | ||
|
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| // Find comment symbol at the end of the line | ||
| var fields []string | ||
|
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| end := strings.IndexRune(trimmed, '#') | ||
|
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| if end == -1 { | ||
| fields = strings.Fields(trimmed) | ||
| } else { | ||
| fields = strings.Fields(trimmed[:end]) | ||
| } | ||
|
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| if len(fields) < 2 { | ||
| // Skip invalid entry | ||
| continue | ||
| } | ||
|
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| if net.ParseIP(fields[0]) == nil { | ||
| // Skip invalid IP address | ||
| continue | ||
| } | ||
|
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| var h host | ||
| h.IP = net.ParseIP(fields[0]) | ||
| h.Hostname = fields[1] | ||
|
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| if len(fields) > 2 { | ||
| for i := 2; i < len(fields); i++ { | ||
| h.Aliases = append(h.Aliases, fields[i]) | ||
| } | ||
| } | ||
|
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| newHosts = append(newHosts, h) | ||
| } | ||
|
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| r.hosts = newHosts | ||
|
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| return nil | ||
| } | ||
|
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| func (r *HostsFileResolver) periodicUpdate() { | ||
| if r.refreshPeriod > 0 { | ||
| ticker := time.NewTicker(r.refreshPeriod) | ||
| defer ticker.Stop() | ||
|
|
||
| for { | ||
| <-ticker.C | ||
|
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| logger := logger(hostsFileResolverLogger) | ||
| logger.WithField("file", r.HostsFilePath).Debug("refreshing hosts file") | ||
|
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| err := r.parseHostsFile() | ||
| if err != nil { | ||
| logger.Warn("can't refresh hosts file: ", err) | ||
| } | ||
| } | ||
| } | ||
| } |
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