2020-05-08 16:39:37 +01:00
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package dnsforward
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import (
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2021-12-03 14:56:07 +00:00
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"encoding/binary"
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2020-08-18 10:36:52 +01:00
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"net"
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2020-06-23 10:13:13 +01:00
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"strings"
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2020-05-08 16:39:37 +01:00
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"time"
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2020-10-30 10:32:02 +00:00
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"github.com/AdguardTeam/AdGuardHome/internal/dhcpd"
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2021-05-21 14:15:47 +01:00
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"github.com/AdguardTeam/AdGuardHome/internal/filtering"
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2020-05-08 16:39:37 +01:00
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"github.com/AdguardTeam/dnsproxy/proxy"
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"github.com/AdguardTeam/golibs/log"
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2021-08-09 14:03:37 +01:00
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"github.com/AdguardTeam/golibs/netutil"
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2021-07-29 15:40:31 +01:00
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"github.com/AdguardTeam/golibs/stringutil"
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2020-05-08 16:39:37 +01:00
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"github.com/miekg/dns"
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)
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// To transfer information between modules
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type dnsContext struct {
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2021-01-27 15:32:13 +00:00
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proxyCtx *proxy.DNSContext
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2021-12-13 15:06:01 +00:00
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2021-01-27 15:32:13 +00:00
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// setts are the filtering settings for the client.
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2021-12-13 15:06:01 +00:00
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setts *filtering.Settings
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result *filtering.Result
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2021-01-27 15:32:13 +00:00
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// origResp is the response received from upstream. It is set when the
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// response is modified by filters.
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origResp *dns.Msg
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2021-12-13 15:06:01 +00:00
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2021-03-31 13:00:47 +01:00
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// unreversedReqIP stores an IP address obtained from PTR request if it
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2021-11-15 14:42:10 +00:00
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// parsed successfully and belongs to one of locally-served IP ranges as per
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// RFC 6303.
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2021-03-31 13:00:47 +01:00
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unreversedReqIP net.IP
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2021-12-13 15:06:01 +00:00
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2021-01-27 15:32:13 +00:00
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// err is the error returned from a processing function.
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err error
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2021-12-13 15:06:01 +00:00
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2022-02-10 12:42:59 +00:00
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// clientID is the ClientID from DoH, DoQ, or DoT, if provided.
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2021-01-27 15:32:13 +00:00
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clientID string
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2021-12-13 15:06:01 +00:00
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2021-01-27 15:32:13 +00:00
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// origQuestion is the question received from the client. It is set
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// when the request is modified by rewrites.
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origQuestion dns.Question
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2021-12-13 15:06:01 +00:00
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// startTime is the time at which the processing of the request has started.
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startTime time.Time
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2021-01-27 15:32:13 +00:00
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// protectionEnabled shows if the filtering is enabled, and if the
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// server's DNS filter is ready.
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protectionEnabled bool
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2021-12-13 15:06:01 +00:00
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2021-01-27 15:32:13 +00:00
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// responseFromUpstream shows if the response is received from the
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// upstream servers.
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responseFromUpstream bool
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2021-12-13 15:06:01 +00:00
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// responseAD shows if the response had the AD bit set.
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responseAD bool
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2021-04-08 16:07:29 +01:00
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// isLocalClient shows if client's IP address is from locally-served
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// network.
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isLocalClient bool
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2020-05-08 16:39:37 +01:00
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}
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2021-01-27 15:32:13 +00:00
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// resultCode is the result of a request processing function.
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type resultCode int
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2020-05-08 16:39:37 +01:00
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const (
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// resultCodeSuccess is returned when a handler performed successfully,
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// and the next handler must be called.
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resultCodeSuccess resultCode = iota
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// resultCodeFinish is returned when a handler performed successfully,
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// and the processing of the request must be stopped.
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resultCodeFinish
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// resultCodeError is returned when a handler failed, and the processing
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// of the request must be stopped.
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resultCodeError
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2020-05-08 16:39:37 +01:00
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)
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2022-04-27 09:39:48 +01:00
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// ddrHostFQDN is the FQDN used in Discovery of Designated Resolvers (DDR) requests.
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// See https://www.ietf.org/archive/id/draft-ietf-add-ddr-06.html.
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const ddrHostFQDN = "_dns.resolver.arpa."
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2020-05-08 16:39:37 +01:00
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// handleDNSRequest filters the incoming DNS requests and writes them to the query log
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2022-09-02 12:52:19 +01:00
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func (s *Server) handleDNSRequest(_ *proxy.Proxy, pctx *proxy.DNSContext) error {
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dctx := &dnsContext{
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proxyCtx: pctx,
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result: &filtering.Result{},
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2021-01-27 15:32:13 +00:00
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startTime: time.Now(),
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}
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2020-05-08 16:39:37 +01:00
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2021-01-27 15:32:13 +00:00
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type modProcessFunc func(ctx *dnsContext) (rc resultCode)
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2020-12-28 16:26:37 +00:00
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// Since (*dnsforward.Server).handleDNSRequest(...) is used as
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// proxy.(Config).RequestHandler, there is no need for additional index
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// out of range checking in any of the following functions, because the
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// (*proxy.Proxy).handleDNSRequest method performs it before calling the
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// appropriate handler.
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2020-05-08 16:39:37 +01:00
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mods := []modProcessFunc{
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2021-05-27 17:19:19 +01:00
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s.processRecursion,
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2021-11-15 14:42:10 +00:00
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s.processInitial,
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2022-04-27 09:39:48 +01:00
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s.processDDRQuery,
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s.processDetermineLocal,
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2022-06-28 17:09:26 +01:00
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s.processDHCPHosts,
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2021-03-31 13:00:47 +01:00
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s.processRestrictLocal,
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2022-06-28 17:09:26 +01:00
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s.processDHCPAddrs,
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2021-10-20 17:52:13 +01:00
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s.processFilteringBeforeRequest,
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2021-03-31 13:00:47 +01:00
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s.processLocalPTR,
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2021-05-27 17:19:19 +01:00
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s.processUpstream,
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s.processFilteringAfterResponse,
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2020-09-02 12:13:45 +01:00
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s.ipset.process,
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2021-11-15 14:42:10 +00:00
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s.processQueryLogsAndStats,
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2020-05-08 16:39:37 +01:00
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}
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for _, process := range mods {
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2022-09-02 12:52:19 +01:00
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r := process(dctx)
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2020-05-08 16:39:37 +01:00
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switch r {
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2021-01-27 15:32:13 +00:00
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case resultCodeSuccess:
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2020-05-08 16:39:37 +01:00
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// continue: call the next filter
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2021-01-27 15:32:13 +00:00
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case resultCodeFinish:
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2020-05-08 16:39:37 +01:00
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return nil
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2021-01-27 15:32:13 +00:00
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case resultCodeError:
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2022-09-02 12:52:19 +01:00
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return dctx.err
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2020-05-08 16:39:37 +01:00
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}
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}
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2022-09-02 12:52:19 +01:00
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if pctx.Res != nil {
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// Some devices require DNS message compression.
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pctx.Res.Compress = true
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2020-05-08 16:39:37 +01:00
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}
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2022-09-02 12:52:19 +01:00
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2020-05-08 16:39:37 +01:00
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return nil
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}
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2021-05-27 17:19:19 +01:00
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// processRecursion checks the incoming request and halts it's handling if s
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// have tried to resolve it recently.
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func (s *Server) processRecursion(dctx *dnsContext) (rc resultCode) {
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pctx := dctx.proxyCtx
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if msg := pctx.Req; msg != nil && s.recDetector.check(*msg) {
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log.Debug("recursion detected resolving %q", msg.Question[0].Name)
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pctx.Res = s.genNXDomain(pctx.Req)
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return resultCodeFinish
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}
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return resultCodeSuccess
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}
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2021-12-03 14:56:07 +00:00
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// processInitial terminates the following processing for some requests if
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// needed and enriches the ctx with some client-specific information.
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//
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// TODO(e.burkov): Decompose into less general processors.
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2022-09-02 12:52:19 +01:00
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func (s *Server) processInitial(dctx *dnsContext) (rc resultCode) {
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pctx := dctx.proxyCtx
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q := pctx.Req.Question[0]
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qt := q.Qtype
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if s.conf.AAAADisabled && qt == dns.TypeAAAA {
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_ = proxy.CheckDisabledAAAARequest(pctx, true)
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2021-01-27 15:32:13 +00:00
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return resultCodeFinish
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2020-05-08 16:39:37 +01:00
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}
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if s.conf.OnDNSRequest != nil {
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2022-09-02 12:52:19 +01:00
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s.conf.OnDNSRequest(pctx)
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2020-05-08 16:39:37 +01:00
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}
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2022-09-02 12:52:19 +01:00
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// Disable Mozilla DoH.
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//
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// See https://support.mozilla.org/en-US/kb/canary-domain-use-application-dnsnet.
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if (qt == dns.TypeA || qt == dns.TypeAAAA) && q.Name == "use-application-dns.net." {
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pctx.Res = s.genNXDomain(pctx.Req)
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2021-01-27 15:32:13 +00:00
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return resultCodeFinish
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2020-05-08 16:39:37 +01:00
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}
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2022-09-02 12:52:19 +01:00
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// Get the ClientID, if any, before getting client-specific filtering
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// settings.
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2021-12-03 14:56:07 +00:00
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var key [8]byte
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2022-09-02 12:52:19 +01:00
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binary.BigEndian.PutUint64(key[:], pctx.RequestID)
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dctx.clientID = string(s.clientIDCache.Get(key[:]))
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2021-12-03 14:56:07 +00:00
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// Get the client-specific filtering settings.
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2022-09-02 12:52:19 +01:00
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dctx.protectionEnabled = s.conf.ProtectionEnabled
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dctx.setts = s.getClientRequestFilteringSettings(dctx)
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2021-11-15 14:42:10 +00:00
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2021-01-27 15:32:13 +00:00
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return resultCodeSuccess
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2020-05-08 16:39:37 +01:00
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}
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2021-04-15 15:52:53 +01:00
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func (s *Server) setTableHostToIP(t hostToIPTable) {
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s.tableHostToIPLock.Lock()
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defer s.tableHostToIPLock.Unlock()
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s.tableHostToIP = t
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}
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2021-08-09 14:03:37 +01:00
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func (s *Server) setTableIPToHost(t *netutil.IPMap) {
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2021-04-15 15:52:53 +01:00
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s.tableIPToHostLock.Lock()
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defer s.tableIPToHostLock.Unlock()
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s.tableIPToHost = t
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}
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2020-06-23 10:13:13 +01:00
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func (s *Server) onDHCPLeaseChanged(flags int) {
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2021-04-19 14:04:40 +01:00
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var err error
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2021-04-15 15:52:53 +01:00
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add := true
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2020-06-23 10:13:13 +01:00
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switch flags {
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case dhcpd.LeaseChangedAdded,
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dhcpd.LeaseChangedAddedStatic,
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dhcpd.LeaseChangedRemovedStatic:
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2021-04-15 15:52:53 +01:00
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// Go on.
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case dhcpd.LeaseChangedRemovedAll:
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add = false
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2020-06-23 10:13:13 +01:00
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default:
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return
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}
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2021-04-15 15:52:53 +01:00
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var hostToIP hostToIPTable
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2021-08-09 14:03:37 +01:00
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var ipToHost *netutil.IPMap
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2021-04-15 15:52:53 +01:00
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if add {
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ll := s.dhcpServer.Leases(dhcpd.LeasesAll)
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2020-08-18 10:36:52 +01:00
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2021-06-29 13:53:28 +01:00
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hostToIP = make(hostToIPTable, len(ll))
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2021-08-09 14:03:37 +01:00
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ipToHost = netutil.NewIPMap(len(ll))
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2021-06-29 13:53:28 +01:00
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2021-04-15 15:52:53 +01:00
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for _, l := range ll {
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2022-01-25 16:47:02 +00:00
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// TODO(a.garipov): Remove this after we're finished with the client
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// hostname validations in the DHCP server code.
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2021-08-09 14:03:37 +01:00
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err = netutil.ValidateDomainName(l.Hostname)
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2021-04-19 14:04:40 +01:00
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if err != nil {
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log.Debug(
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"dns: skipping invalid hostname %q from dhcp: %s",
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l.Hostname,
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err,
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)
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2021-04-15 15:52:53 +01:00
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}
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2020-08-18 15:40:36 +01:00
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2022-06-28 17:09:26 +01:00
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lowhost := strings.ToLower(l.Hostname + "." + s.localDomainSuffix)
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ip := netutil.CloneIP(l.IP)
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2020-08-18 10:36:52 +01:00
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2022-06-28 17:09:26 +01:00
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ipToHost.Set(ip, lowhost)
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2021-04-15 15:52:53 +01:00
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hostToIP[lowhost] = ip
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}
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2020-08-18 10:36:52 +01:00
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2021-06-29 13:53:28 +01:00
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log.Debug("dns: added %d A/PTR entries from DHCP", ipToHost.Len())
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2021-04-15 15:52:53 +01:00
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}
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2020-08-18 10:36:52 +01:00
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2021-04-15 15:52:53 +01:00
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s.setTableHostToIP(hostToIP)
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s.setTableIPToHost(ipToHost)
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2020-06-23 10:13:13 +01:00
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}
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2022-09-02 14:56:59 +01:00
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// processDDRQuery responds to Discovery of Designated Resolvers (DDR) SVCB
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// queries. The response contains different types of encryption supported by
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// current user configuration.
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2022-04-27 09:39:48 +01:00
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//
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2022-09-02 14:56:59 +01:00
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// See https://www.ietf.org/archive/id/draft-ietf-add-ddr-10.html.
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2022-09-02 12:52:19 +01:00
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func (s *Server) processDDRQuery(dctx *dnsContext) (rc resultCode) {
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pctx := dctx.proxyCtx
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q := pctx.Req.Question[0]
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2022-04-27 09:39:48 +01:00
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if !s.conf.HandleDDR {
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return resultCodeSuccess
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}
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2022-09-02 12:52:19 +01:00
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if q.Name == ddrHostFQDN {
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2022-05-31 15:28:50 +01:00
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if s.dnsProxy.TLSListenAddr == nil && s.conf.HTTPSListenAddrs == nil &&
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2022-09-02 12:52:19 +01:00
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s.dnsProxy.QUICListenAddr == nil || q.Qtype != dns.TypeSVCB {
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pctx.Res = s.makeResponse(pctx.Req)
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2022-04-27 09:39:48 +01:00
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return resultCodeFinish
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}
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2022-09-02 12:52:19 +01:00
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pctx.Res = s.makeDDRResponse(pctx.Req)
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2022-04-27 09:39:48 +01:00
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return resultCodeFinish
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}
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return resultCodeSuccess
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}
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|
2022-09-02 14:56:59 +01:00
|
|
|
// makeDDRResponse creates a DDR answer based on the server configuration. The
|
|
|
|
// constructed SVCB resource records have the priority of 1 for each entry,
|
|
|
|
// similar to examples provided by the [draft standard].
|
2022-06-20 15:48:56 +01:00
|
|
|
//
|
|
|
|
// TODO(a.meshkov): Consider setting the priority values based on the protocol.
|
2022-09-02 14:56:59 +01:00
|
|
|
//
|
|
|
|
// [draft standard]: https://www.ietf.org/archive/id/draft-ietf-add-ddr-10.html.
|
2022-04-27 09:39:48 +01:00
|
|
|
func (s *Server) makeDDRResponse(req *dns.Msg) (resp *dns.Msg) {
|
|
|
|
resp = s.makeResponse(req)
|
2022-05-31 15:28:50 +01:00
|
|
|
// TODO(e.burkov): Think about storing the FQDN version of the server's
|
2022-05-30 14:04:28 +01:00
|
|
|
// name somewhere.
|
|
|
|
domainName := dns.Fqdn(s.conf.ServerName)
|
2022-04-27 09:39:48 +01:00
|
|
|
|
2022-05-31 15:28:50 +01:00
|
|
|
for _, addr := range s.conf.HTTPSListenAddrs {
|
2022-04-27 09:39:48 +01:00
|
|
|
values := []dns.SVCBKeyValue{
|
|
|
|
&dns.SVCBAlpn{Alpn: []string{"h2"}},
|
|
|
|
&dns.SVCBPort{Port: uint16(addr.Port)},
|
2022-09-20 13:26:10 +01:00
|
|
|
&dns.SVCBDoHPath{Template: "/dns-query{?dns}"},
|
2022-04-27 09:39:48 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
ans := &dns.SVCB{
|
|
|
|
Hdr: s.hdr(req, dns.TypeSVCB),
|
|
|
|
Priority: 1,
|
|
|
|
Target: domainName,
|
|
|
|
Value: values,
|
|
|
|
}
|
|
|
|
|
|
|
|
resp.Answer = append(resp.Answer, ans)
|
|
|
|
}
|
|
|
|
|
|
|
|
for _, addr := range s.dnsProxy.TLSListenAddr {
|
|
|
|
values := []dns.SVCBKeyValue{
|
|
|
|
&dns.SVCBAlpn{Alpn: []string{"dot"}},
|
|
|
|
&dns.SVCBPort{Port: uint16(addr.Port)},
|
|
|
|
}
|
|
|
|
|
|
|
|
ans := &dns.SVCB{
|
|
|
|
Hdr: s.hdr(req, dns.TypeSVCB),
|
2022-06-20 15:48:56 +01:00
|
|
|
Priority: 1,
|
2022-04-27 09:39:48 +01:00
|
|
|
Target: domainName,
|
|
|
|
Value: values,
|
|
|
|
}
|
|
|
|
|
|
|
|
resp.Answer = append(resp.Answer, ans)
|
|
|
|
}
|
|
|
|
|
2022-05-26 15:53:11 +01:00
|
|
|
for _, addr := range s.dnsProxy.QUICListenAddr {
|
|
|
|
values := []dns.SVCBKeyValue{
|
|
|
|
&dns.SVCBAlpn{Alpn: []string{"doq"}},
|
|
|
|
&dns.SVCBPort{Port: uint16(addr.Port)},
|
|
|
|
}
|
|
|
|
|
|
|
|
ans := &dns.SVCB{
|
|
|
|
Hdr: s.hdr(req, dns.TypeSVCB),
|
2022-06-20 15:48:56 +01:00
|
|
|
Priority: 1,
|
2022-05-26 15:53:11 +01:00
|
|
|
Target: domainName,
|
|
|
|
Value: values,
|
|
|
|
}
|
|
|
|
|
|
|
|
resp.Answer = append(resp.Answer, ans)
|
|
|
|
}
|
|
|
|
|
2022-04-27 09:39:48 +01:00
|
|
|
return resp
|
|
|
|
}
|
|
|
|
|
2021-04-08 16:07:29 +01:00
|
|
|
// processDetermineLocal determines if the client's IP address is from
|
|
|
|
// locally-served network and saves the result into the context.
|
|
|
|
func (s *Server) processDetermineLocal(dctx *dnsContext) (rc resultCode) {
|
|
|
|
rc = resultCodeSuccess
|
|
|
|
|
|
|
|
var ip net.IP
|
2021-08-09 14:03:37 +01:00
|
|
|
if ip, _ = netutil.IPAndPortFromAddr(dctx.proxyCtx.Addr); ip == nil {
|
2021-04-08 16:07:29 +01:00
|
|
|
return rc
|
|
|
|
}
|
|
|
|
|
2022-03-18 10:37:27 +00:00
|
|
|
dctx.isLocalClient = s.privateNets.Contains(ip)
|
2021-04-08 16:07:29 +01:00
|
|
|
|
|
|
|
return rc
|
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
// dhcpHostToIP tries to get an IP leased by DHCP and returns the copy of
|
|
|
|
// address since the data inside the internal table may be changed while request
|
2021-03-31 13:00:47 +01:00
|
|
|
// processing. It's safe for concurrent use.
|
2022-09-02 14:56:59 +01:00
|
|
|
func (s *Server) dhcpHostToIP(host string) (ip net.IP, ok bool) {
|
2021-03-31 13:00:47 +01:00
|
|
|
s.tableHostToIPLock.Lock()
|
|
|
|
defer s.tableHostToIPLock.Unlock()
|
|
|
|
|
|
|
|
if s.tableHostToIP == nil {
|
|
|
|
return nil, false
|
|
|
|
}
|
|
|
|
|
|
|
|
var ipFromTable net.IP
|
|
|
|
ipFromTable, ok = s.tableHostToIP[host]
|
|
|
|
if !ok {
|
|
|
|
return nil, false
|
|
|
|
}
|
|
|
|
|
|
|
|
ip = make(net.IP, len(ipFromTable))
|
|
|
|
copy(ip, ipFromTable)
|
|
|
|
|
|
|
|
return ip, true
|
|
|
|
}
|
|
|
|
|
2022-06-28 17:09:26 +01:00
|
|
|
// processDHCPHosts respond to A requests if the target hostname is known to
|
2021-03-25 13:00:27 +00:00
|
|
|
// the server.
|
|
|
|
//
|
|
|
|
// TODO(a.garipov): Adapt to AAAA as well.
|
2022-06-28 17:09:26 +01:00
|
|
|
func (s *Server) processDHCPHosts(dctx *dnsContext) (rc resultCode) {
|
2022-09-02 14:56:59 +01:00
|
|
|
pctx := dctx.proxyCtx
|
|
|
|
req := pctx.Req
|
2021-03-25 13:00:27 +00:00
|
|
|
q := req.Question[0]
|
2022-09-02 14:56:59 +01:00
|
|
|
reqHost, ok := s.isDHCPClientHostQ(q)
|
|
|
|
if !ok {
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-08-18 10:36:52 +01:00
|
|
|
}
|
|
|
|
|
2021-04-08 16:07:29 +01:00
|
|
|
if !dctx.isLocalClient {
|
2022-09-02 14:56:59 +01:00
|
|
|
log.Debug("dns: %q requests for dhcp host %q", pctx.Addr, reqHost)
|
2022-09-02 12:52:19 +01:00
|
|
|
pctx.Res = s.genNXDomain(req)
|
2021-04-08 16:07:29 +01:00
|
|
|
|
|
|
|
// Do not even put into query log.
|
|
|
|
return resultCodeFinish
|
|
|
|
}
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
ip, ok := s.dhcpHostToIP(reqHost)
|
2020-08-18 10:36:52 +01:00
|
|
|
if !ok {
|
2022-09-02 14:56:59 +01:00
|
|
|
// Go on and process them with filters, including dnsrewrite ones, and
|
|
|
|
// possibly route them to a domain-specific upstream.
|
|
|
|
log.Debug("dns: no dhcp record for %q", reqHost)
|
2021-04-08 16:07:29 +01:00
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
return resultCodeSuccess
|
2020-08-18 10:36:52 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
log.Debug("dns: dhcp record for %q is %s", reqHost, ip)
|
2020-08-18 10:36:52 +01:00
|
|
|
|
|
|
|
resp := s.makeResponse(req)
|
2021-03-25 13:00:27 +00:00
|
|
|
if q.Qtype == dns.TypeA {
|
|
|
|
a := &dns.A{
|
|
|
|
Hdr: s.hdr(req, dns.TypeA),
|
2021-03-31 13:00:47 +01:00
|
|
|
A: ip,
|
2020-08-18 10:36:52 +01:00
|
|
|
}
|
|
|
|
resp.Answer = append(resp.Answer, a)
|
|
|
|
}
|
2021-03-25 13:00:27 +00:00
|
|
|
dctx.proxyCtx.Res = resp
|
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2021-04-08 16:07:29 +01:00
|
|
|
// processRestrictLocal responds with NXDOMAIN to PTR requests for IP addresses
|
|
|
|
// in locally-served network from external clients.
|
2022-09-02 12:52:19 +01:00
|
|
|
func (s *Server) processRestrictLocal(dctx *dnsContext) (rc resultCode) {
|
|
|
|
pctx := dctx.proxyCtx
|
|
|
|
req := pctx.Req
|
2021-03-31 13:00:47 +01:00
|
|
|
q := req.Question[0]
|
|
|
|
if q.Qtype != dns.TypePTR {
|
|
|
|
// No need for restriction.
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
|
2021-08-09 14:03:37 +01:00
|
|
|
ip, err := netutil.IPFromReversedAddr(q.Name)
|
|
|
|
if err != nil {
|
2022-01-18 11:20:25 +00:00
|
|
|
log.Debug("dns: parsing reversed addr: %s", err)
|
2021-08-09 14:03:37 +01:00
|
|
|
|
2022-01-18 11:20:25 +00:00
|
|
|
// DNS-Based Service Discovery uses PTR records having not an ARPA
|
|
|
|
// format of the domain name in question. Those shouldn't be
|
|
|
|
// invalidated. See http://www.dns-sd.org/ServerStaticSetup.html and
|
|
|
|
// RFC 2782.
|
|
|
|
name := strings.TrimSuffix(q.Name, ".")
|
|
|
|
if err = netutil.ValidateSRVDomainName(name); err != nil {
|
|
|
|
log.Debug("dns: validating service domain: %s", err)
|
|
|
|
|
|
|
|
return resultCodeError
|
|
|
|
}
|
|
|
|
|
|
|
|
log.Debug("dns: request is for a service domain")
|
|
|
|
|
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
|
2021-03-31 13:00:47 +01:00
|
|
|
// Restrict an access to local addresses for external clients. We also
|
2021-11-15 14:42:10 +00:00
|
|
|
// assume that all the DHCP leases we give are locally-served or at least
|
2022-06-28 17:09:26 +01:00
|
|
|
// don't need to be accessible externally.
|
2022-03-18 10:37:27 +00:00
|
|
|
if !s.privateNets.Contains(ip) {
|
2021-11-15 14:42:10 +00:00
|
|
|
log.Debug("dns: addr %s is not from locally-served network", ip)
|
|
|
|
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
if !dctx.isLocalClient {
|
|
|
|
log.Debug("dns: %q requests an internal ip", pctx.Addr)
|
|
|
|
pctx.Res = s.genNXDomain(req)
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-11-11 13:19:33 +00:00
|
|
|
// Do not even put into query log.
|
|
|
|
return resultCodeFinish
|
2021-03-31 13:00:47 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// Do not perform unreversing ever again.
|
2022-09-02 12:52:19 +01:00
|
|
|
dctx.unreversedReqIP = ip
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-11-15 14:42:10 +00:00
|
|
|
// There is no need to filter request from external addresses since this
|
|
|
|
// code is only executed when the request is for locally-served ARPA
|
|
|
|
// hostname so disable redundant filters.
|
2022-09-02 12:52:19 +01:00
|
|
|
dctx.setts.ParentalEnabled = false
|
|
|
|
dctx.setts.SafeBrowsingEnabled = false
|
|
|
|
dctx.setts.SafeSearchEnabled = false
|
|
|
|
dctx.setts.ServicesRules = nil
|
2021-04-07 18:16:06 +01:00
|
|
|
|
2021-03-31 13:00:47 +01:00
|
|
|
// Nothing to restrict.
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
// ipToDHCPHost tries to get a hostname leased by DHCP. It's safe for
|
|
|
|
// concurrent use.
|
|
|
|
func (s *Server) ipToDHCPHost(ip net.IP) (host string, ok bool) {
|
2021-04-15 15:52:53 +01:00
|
|
|
s.tableIPToHostLock.Lock()
|
|
|
|
defer s.tableIPToHostLock.Unlock()
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-04-15 15:52:53 +01:00
|
|
|
if s.tableIPToHost == nil {
|
2021-03-31 13:00:47 +01:00
|
|
|
return "", false
|
|
|
|
}
|
|
|
|
|
2022-08-03 12:36:18 +01:00
|
|
|
var v any
|
2021-06-29 13:53:28 +01:00
|
|
|
v, ok = s.tableIPToHost.Get(ip)
|
2021-07-06 13:08:55 +01:00
|
|
|
if !ok {
|
|
|
|
return "", false
|
|
|
|
}
|
2021-06-29 13:53:28 +01:00
|
|
|
|
2021-07-06 13:08:55 +01:00
|
|
|
if host, ok = v.(string); !ok {
|
2021-06-29 13:53:28 +01:00
|
|
|
log.Error("dns: bad type %T in tableIPToHost for %s", v, ip)
|
|
|
|
|
|
|
|
return "", false
|
|
|
|
}
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-07-06 13:08:55 +01:00
|
|
|
return host, true
|
2021-03-31 13:00:47 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
// processDHCPAddrs responds to PTR requests if the target IP is leased by the
|
|
|
|
// DHCP server.
|
2022-09-02 12:52:19 +01:00
|
|
|
func (s *Server) processDHCPAddrs(dctx *dnsContext) (rc resultCode) {
|
|
|
|
pctx := dctx.proxyCtx
|
|
|
|
if pctx.Res != nil {
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
ip := dctx.unreversedReqIP
|
2021-03-31 13:00:47 +01:00
|
|
|
if ip == nil {
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
host, ok := s.ipToDHCPHost(ip)
|
2020-06-23 10:13:13 +01:00
|
|
|
if !ok {
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
log.Debug("dns: dhcp reverse record for %s is %q", ip, host)
|
2020-06-23 10:13:13 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
req := pctx.Req
|
2020-06-23 10:13:13 +01:00
|
|
|
resp := s.makeResponse(req)
|
2021-03-31 13:00:47 +01:00
|
|
|
ptr := &dns.PTR{
|
|
|
|
Hdr: dns.RR_Header{
|
|
|
|
Name: req.Question[0].Name,
|
|
|
|
Rrtype: dns.TypePTR,
|
|
|
|
Ttl: s.conf.BlockedResponseTTL,
|
|
|
|
Class: dns.ClassINET,
|
|
|
|
},
|
|
|
|
Ptr: dns.Fqdn(host),
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
resp.Answer = append(resp.Answer, ptr)
|
2022-09-02 12:52:19 +01:00
|
|
|
pctx.Res = resp
|
2021-03-31 13:00:47 +01:00
|
|
|
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
|
|
|
// processLocalPTR responds to PTR requests if the target IP is detected to be
|
|
|
|
// inside the local network and the query was not answered from DHCP.
|
2022-09-02 12:52:19 +01:00
|
|
|
func (s *Server) processLocalPTR(dctx *dnsContext) (rc resultCode) {
|
|
|
|
pctx := dctx.proxyCtx
|
|
|
|
if pctx.Res != nil {
|
2021-03-31 13:00:47 +01:00
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
ip := dctx.unreversedReqIP
|
2021-03-31 13:00:47 +01:00
|
|
|
if ip == nil {
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
s.serverLock.RLock()
|
|
|
|
defer s.serverLock.RUnlock()
|
|
|
|
|
2022-03-18 10:37:27 +00:00
|
|
|
if !s.privateNets.Contains(ip) {
|
2021-03-31 13:00:47 +01:00
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
if s.conf.UsePrivateRDNS {
|
2022-09-02 12:52:19 +01:00
|
|
|
s.recDetector.add(*pctx.Req)
|
|
|
|
if err := s.localResolvers.Resolve(pctx); err != nil {
|
|
|
|
dctx.err = err
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
return resultCodeError
|
|
|
|
}
|
2021-03-31 13:00:47 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
if pctx.Res == nil {
|
|
|
|
pctx.Res = s.genNXDomain(pctx.Req)
|
2021-04-09 19:01:21 +01:00
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
// Do not even put into query log.
|
2021-04-09 19:01:21 +01:00
|
|
|
return resultCodeFinish
|
|
|
|
}
|
2021-03-31 13:00:47 +01:00
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
|
2020-05-08 16:39:37 +01:00
|
|
|
// Apply filtering logic
|
2021-10-20 17:52:13 +01:00
|
|
|
func (s *Server) processFilteringBeforeRequest(ctx *dnsContext) (rc resultCode) {
|
|
|
|
if ctx.proxyCtx.Res != nil {
|
|
|
|
// Go on since the response is already set.
|
|
|
|
return resultCodeSuccess
|
2020-06-23 10:13:13 +01:00
|
|
|
}
|
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
s.serverLock.RLock()
|
|
|
|
defer s.serverLock.RUnlock()
|
2020-05-08 16:39:37 +01:00
|
|
|
|
2021-10-20 17:52:13 +01:00
|
|
|
if s.dnsFilter == nil {
|
2021-05-26 15:55:19 +01:00
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2021-05-26 15:55:19 +01:00
|
|
|
var err error
|
2021-10-20 17:52:13 +01:00
|
|
|
if ctx.result, err = s.filterDNSRequest(ctx); err != nil {
|
2020-05-08 16:39:37 +01:00
|
|
|
ctx.err = err
|
2021-04-07 18:16:06 +01:00
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeError
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
2021-04-07 18:16:06 +01:00
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2021-05-28 11:02:59 +01:00
|
|
|
// ipStringFromAddr extracts an IP address string from net.Addr.
|
|
|
|
func ipStringFromAddr(addr net.Addr) (ipStr string) {
|
2021-08-09 14:03:37 +01:00
|
|
|
if ip, _ := netutil.IPAndPortFromAddr(addr); ip != nil {
|
2021-05-28 11:02:59 +01:00
|
|
|
return ip.String()
|
|
|
|
}
|
|
|
|
|
|
|
|
return ""
|
|
|
|
}
|
|
|
|
|
2021-01-13 13:56:05 +00:00
|
|
|
// processUpstream passes request to upstream servers and handles the response.
|
2021-12-13 15:06:01 +00:00
|
|
|
func (s *Server) processUpstream(dctx *dnsContext) (rc resultCode) {
|
|
|
|
pctx := dctx.proxyCtx
|
2022-09-02 14:56:59 +01:00
|
|
|
req := pctx.Req
|
|
|
|
q := req.Question[0]
|
2021-12-13 15:06:01 +00:00
|
|
|
if pctx.Res != nil {
|
|
|
|
// The response has already been set.
|
|
|
|
return resultCodeSuccess
|
2022-09-02 14:56:59 +01:00
|
|
|
} else if reqHost, ok := s.isDHCPClientHostQ(q); ok {
|
|
|
|
// A DHCP client hostname query that hasn't been handled or filtered.
|
|
|
|
// Respond with an NXDOMAIN.
|
|
|
|
//
|
|
|
|
// TODO(a.garipov): Route such queries to a custom upstream for the
|
|
|
|
// local domain name if there is one.
|
|
|
|
log.Debug("dns: dhcp client hostname %q was not filtered", reqHost)
|
|
|
|
pctx.Res = s.genNXDomain(req)
|
|
|
|
|
|
|
|
return resultCodeFinish
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
s.setCustomUpstream(pctx, dctx.clientID)
|
2020-05-08 16:39:37 +01:00
|
|
|
|
2021-12-13 15:06:01 +00:00
|
|
|
origReqAD := false
|
2020-05-08 16:39:37 +01:00
|
|
|
if s.conf.EnableDNSSEC {
|
2021-12-13 15:06:01 +00:00
|
|
|
if req.AuthenticatedData {
|
|
|
|
origReqAD = true
|
2020-05-08 16:39:37 +01:00
|
|
|
} else {
|
2021-12-13 15:06:01 +00:00
|
|
|
req.AuthenticatedData = true
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2021-10-06 11:14:41 +01:00
|
|
|
// Process the request further since it wasn't filtered.
|
|
|
|
prx := s.proxy()
|
|
|
|
if prx == nil {
|
2021-12-13 15:06:01 +00:00
|
|
|
dctx.err = srvClosedErr
|
2021-10-06 11:14:41 +01:00
|
|
|
|
|
|
|
return resultCodeError
|
|
|
|
}
|
|
|
|
|
2021-12-13 15:06:01 +00:00
|
|
|
if dctx.err = prx.Resolve(pctx); dctx.err != nil {
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeError
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2021-12-13 15:06:01 +00:00
|
|
|
dctx.responseFromUpstream = true
|
|
|
|
dctx.responseAD = pctx.Res.AuthenticatedData
|
2020-05-08 16:39:37 +01:00
|
|
|
|
2021-12-13 15:06:01 +00:00
|
|
|
if s.conf.EnableDNSSEC && !origReqAD {
|
|
|
|
pctx.Req.AuthenticatedData = false
|
|
|
|
pctx.Res.AuthenticatedData = false
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 14:56:59 +01:00
|
|
|
// isDHCPClientHostQ returns true if q is from a request for a DHCP client
|
|
|
|
// hostname. If ok is true, reqHost contains the requested hostname.
|
|
|
|
func (s *Server) isDHCPClientHostQ(q dns.Question) (reqHost string, ok bool) {
|
|
|
|
if !s.dhcpServer.Enabled() {
|
|
|
|
return "", false
|
|
|
|
}
|
|
|
|
|
|
|
|
// Include AAAA here, because despite the fact that we don't support it yet,
|
|
|
|
// the expected behavior here is to respond with an empty answer and not
|
|
|
|
// NXDOMAIN.
|
|
|
|
if qt := q.Qtype; qt != dns.TypeA && qt != dns.TypeAAAA {
|
|
|
|
return "", false
|
|
|
|
}
|
|
|
|
|
|
|
|
reqHost = strings.ToLower(q.Name[:len(q.Name)-1])
|
|
|
|
if strings.HasSuffix(reqHost, s.localDomainSuffix) {
|
|
|
|
return reqHost, true
|
|
|
|
}
|
|
|
|
|
|
|
|
return "", false
|
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
// setCustomUpstream sets custom upstream settings in pctx, if necessary.
|
|
|
|
func (s *Server) setCustomUpstream(pctx *proxy.DNSContext, clientID string) {
|
|
|
|
customUpsByClient := s.conf.GetCustomUpstreamByClient
|
|
|
|
if pctx.Addr == nil || customUpsByClient == nil {
|
|
|
|
return
|
|
|
|
}
|
|
|
|
|
|
|
|
// Use the ClientID first, since it has a higher priority.
|
|
|
|
id := stringutil.Coalesce(clientID, ipStringFromAddr(pctx.Addr))
|
|
|
|
upsConf, err := customUpsByClient(id)
|
|
|
|
if err != nil {
|
|
|
|
log.Error("dns: getting custom upstreams for client %s: %s", id, err)
|
2020-05-08 16:39:37 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
return
|
|
|
|
}
|
|
|
|
|
|
|
|
if upsConf != nil {
|
|
|
|
log.Debug("dns: using custom upstreams for client %s", id)
|
|
|
|
}
|
|
|
|
|
|
|
|
pctx.CustomUpstreamConfig = upsConf
|
|
|
|
}
|
|
|
|
|
|
|
|
// Apply filtering logic after we have received response from upstream servers
|
|
|
|
func (s *Server) processFilteringAfterResponse(dctx *dnsContext) (rc resultCode) {
|
|
|
|
pctx := dctx.proxyCtx
|
|
|
|
switch res := dctx.result; res.Reason {
|
2021-10-20 17:52:13 +01:00
|
|
|
case filtering.NotFilteredAllowList:
|
2022-09-02 12:52:19 +01:00
|
|
|
return resultCodeSuccess
|
2021-10-20 17:52:13 +01:00
|
|
|
case
|
|
|
|
filtering.Rewritten,
|
2021-05-21 14:15:47 +01:00
|
|
|
filtering.RewrittenRule:
|
2020-12-21 14:48:07 +00:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
if dctx.origQuestion.Name == "" {
|
2021-10-20 17:52:13 +01:00
|
|
|
// origQuestion is set in case we get only CNAME without IP from
|
|
|
|
// rewrites table.
|
2022-09-02 12:52:19 +01:00
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
2020-06-01 13:23:08 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
pctx.Req.Question[0], pctx.Res.Question[0] = dctx.origQuestion, dctx.origQuestion
|
|
|
|
if len(pctx.Res.Answer) > 0 {
|
|
|
|
rr := s.genAnswerCNAME(pctx.Req, res.CanonName)
|
|
|
|
answer := append([]dns.RR{rr}, pctx.Res.Answer...)
|
|
|
|
pctx.Res.Answer = answer
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
2022-09-02 12:52:19 +01:00
|
|
|
|
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
default:
|
2022-09-02 12:52:19 +01:00
|
|
|
return s.filterAfterResponse(dctx, pctx)
|
|
|
|
}
|
|
|
|
}
|
2021-10-20 17:52:13 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
// filterAfterResponse returns the result of filtering the response that wasn't
|
|
|
|
// explicitly allowed or rewritten.
|
|
|
|
func (s *Server) filterAfterResponse(dctx *dnsContext, pctx *proxy.DNSContext) (res resultCode) {
|
|
|
|
// Check the response only if it's from an upstream. Don't check the
|
|
|
|
// response if the protection is disabled since dnsrewrite rules aren't
|
|
|
|
// applied to it anyway.
|
|
|
|
if !dctx.protectionEnabled || !dctx.responseFromUpstream || s.dnsFilter == nil {
|
|
|
|
return resultCodeSuccess
|
|
|
|
}
|
2021-10-20 17:52:13 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
result, err := s.filterDNSResponse(pctx, dctx.setts)
|
|
|
|
if err != nil {
|
|
|
|
dctx.err = err
|
2021-10-20 17:52:13 +01:00
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
return resultCodeError
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|
|
|
|
|
2022-09-02 12:52:19 +01:00
|
|
|
if result != nil {
|
|
|
|
dctx.result = result
|
|
|
|
dctx.origResp = pctx.Res
|
2021-10-20 17:52:13 +01:00
|
|
|
}
|
|
|
|
|
2021-01-27 15:32:13 +00:00
|
|
|
return resultCodeSuccess
|
2020-05-08 16:39:37 +01:00
|
|
|
}
|