647 lines
16 KiB
Go
647 lines
16 KiB
Go
package dnsforward
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import (
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"encoding/json"
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"fmt"
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"net"
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"net/http"
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"strconv"
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"strings"
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"github.com/AdguardTeam/AdGuardHome/internal/agherr"
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"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
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"github.com/AdguardTeam/AdGuardHome/internal/aghstrings"
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"github.com/AdguardTeam/dnsproxy/proxy"
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"github.com/AdguardTeam/dnsproxy/upstream"
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"github.com/AdguardTeam/golibs/log"
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"github.com/miekg/dns"
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)
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func httpError(r *http.Request, w http.ResponseWriter, code int, format string, args ...interface{}) {
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text := fmt.Sprintf(format, args...)
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log.Info("dns: %s %s: %s", r.Method, r.URL, text)
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http.Error(w, text, code)
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}
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type dnsConfig struct {
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Upstreams *[]string `json:"upstream_dns"`
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UpstreamsFile *string `json:"upstream_dns_file"`
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Bootstraps *[]string `json:"bootstrap_dns"`
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ProtectionEnabled *bool `json:"protection_enabled"`
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RateLimit *uint32 `json:"ratelimit"`
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BlockingMode *string `json:"blocking_mode"`
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BlockingIPv4 net.IP `json:"blocking_ipv4"`
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BlockingIPv6 net.IP `json:"blocking_ipv6"`
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EDNSCSEnabled *bool `json:"edns_cs_enabled"`
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DNSSECEnabled *bool `json:"dnssec_enabled"`
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DisableIPv6 *bool `json:"disable_ipv6"`
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UpstreamMode *string `json:"upstream_mode"`
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CacheSize *uint32 `json:"cache_size"`
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CacheMinTTL *uint32 `json:"cache_ttl_min"`
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CacheMaxTTL *uint32 `json:"cache_ttl_max"`
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ResolveClients *bool `json:"resolve_clients"`
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LocalPTRUpstreams *[]string `json:"local_ptr_upstreams"`
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}
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func (s *Server) getDNSConfig() dnsConfig {
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s.RLock()
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defer s.RUnlock()
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upstreams := aghstrings.CloneSliceOrEmpty(s.conf.UpstreamDNS)
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upstreamFile := s.conf.UpstreamDNSFileName
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bootstraps := aghstrings.CloneSliceOrEmpty(s.conf.BootstrapDNS)
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protectionEnabled := s.conf.ProtectionEnabled
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blockingMode := s.conf.BlockingMode
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blockingIPv4 := s.conf.BlockingIPv4
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blockingIPv6 := s.conf.BlockingIPv6
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ratelimit := s.conf.Ratelimit
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enableEDNSClientSubnet := s.conf.EnableEDNSClientSubnet
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enableDNSSEC := s.conf.EnableDNSSEC
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aaaaDisabled := s.conf.AAAADisabled
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cacheSize := s.conf.CacheSize
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cacheMinTTL := s.conf.CacheMinTTL
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cacheMaxTTL := s.conf.CacheMaxTTL
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resolveClients := s.conf.ResolveClients
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localPTRUpstreams := aghstrings.CloneSliceOrEmpty(s.conf.LocalPTRResolvers)
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var upstreamMode string
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if s.conf.FastestAddr {
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upstreamMode = "fastest_addr"
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} else if s.conf.AllServers {
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upstreamMode = "parallel"
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}
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return dnsConfig{
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Upstreams: &upstreams,
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UpstreamsFile: &upstreamFile,
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Bootstraps: &bootstraps,
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ProtectionEnabled: &protectionEnabled,
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BlockingMode: &blockingMode,
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BlockingIPv4: blockingIPv4,
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BlockingIPv6: blockingIPv6,
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RateLimit: &ratelimit,
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EDNSCSEnabled: &enableEDNSClientSubnet,
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DNSSECEnabled: &enableDNSSEC,
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DisableIPv6: &aaaaDisabled,
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CacheSize: &cacheSize,
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CacheMinTTL: &cacheMinTTL,
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CacheMaxTTL: &cacheMaxTTL,
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UpstreamMode: &upstreamMode,
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ResolveClients: &resolveClients,
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LocalPTRUpstreams: &localPTRUpstreams,
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}
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}
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func (s *Server) handleGetConfig(w http.ResponseWriter, r *http.Request) {
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resp := s.getDNSConfig()
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w.Header().Set("Content-Type", "application/json")
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enc := json.NewEncoder(w)
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if err := enc.Encode(resp); err != nil {
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httpError(r, w, http.StatusInternalServerError, "json.Encoder: %s", err)
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return
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}
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}
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func (req *dnsConfig) checkBlockingMode() bool {
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if req.BlockingMode == nil {
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return true
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}
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bm := *req.BlockingMode
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if bm == "custom_ip" {
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if req.BlockingIPv4.To4() == nil {
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return false
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}
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return req.BlockingIPv6 != nil
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}
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for _, valid := range []string{
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"default",
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"refused",
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"nxdomain",
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"null_ip",
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} {
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if bm == valid {
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return true
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}
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}
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return false
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}
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func (req *dnsConfig) checkUpstreamsMode() bool {
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if req.UpstreamMode == nil {
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return true
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}
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for _, valid := range []string{
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"",
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"fastest_addr",
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"parallel",
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} {
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if *req.UpstreamMode == valid {
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return true
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}
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}
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return false
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}
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func (req *dnsConfig) checkBootstrap() (string, error) {
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if req.Bootstraps == nil {
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return "", nil
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}
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for _, boot := range *req.Bootstraps {
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if boot == "" {
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return boot, fmt.Errorf("invalid bootstrap server address: empty")
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}
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if _, err := upstream.NewResolver(boot, upstream.Options{Timeout: 0}); err != nil {
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return boot, fmt.Errorf("invalid bootstrap server address: %w", err)
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}
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}
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return "", nil
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}
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func (req *dnsConfig) checkCacheTTL() bool {
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if req.CacheMinTTL == nil && req.CacheMaxTTL == nil {
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return true
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}
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var min, max uint32
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if req.CacheMinTTL != nil {
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min = *req.CacheMinTTL
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}
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if req.CacheMaxTTL != nil {
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max = *req.CacheMaxTTL
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}
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return min <= max
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}
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func (s *Server) handleSetConfig(w http.ResponseWriter, r *http.Request) {
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req := dnsConfig{}
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dec := json.NewDecoder(r.Body)
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if err := dec.Decode(&req); err != nil {
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httpError(r, w, http.StatusBadRequest, "json Encode: %s", err)
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return
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}
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if req.Upstreams != nil {
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if err := ValidateUpstreams(*req.Upstreams); err != nil {
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httpError(r, w, http.StatusBadRequest, "wrong upstreams specification: %s", err)
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return
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}
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}
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if errBoot, err := req.checkBootstrap(); err != nil {
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httpError(r, w, http.StatusBadRequest, "%s can not be used as bootstrap dns cause: %s", errBoot, err)
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return
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}
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if !req.checkBlockingMode() {
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httpError(r, w, http.StatusBadRequest, "blocking_mode: incorrect value")
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return
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}
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if !req.checkUpstreamsMode() {
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httpError(r, w, http.StatusBadRequest, "upstream_mode: incorrect value")
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return
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}
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if !req.checkCacheTTL() {
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httpError(r, w, http.StatusBadRequest, "cache_ttl_min must be less or equal than cache_ttl_max")
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return
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}
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restart := s.setConfig(req)
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s.conf.ConfigModified()
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if restart {
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if err := s.Reconfigure(nil); err != nil {
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httpError(r, w, http.StatusInternalServerError, "%s", err)
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return
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}
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}
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}
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func (s *Server) setConfigRestartable(dc dnsConfig) (restart bool) {
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if dc.Upstreams != nil {
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s.conf.UpstreamDNS = *dc.Upstreams
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restart = true
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}
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if dc.LocalPTRUpstreams != nil {
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s.conf.LocalPTRResolvers = *dc.LocalPTRUpstreams
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restart = true
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}
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if dc.UpstreamsFile != nil {
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s.conf.UpstreamDNSFileName = *dc.UpstreamsFile
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restart = true
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}
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if dc.Bootstraps != nil {
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s.conf.BootstrapDNS = *dc.Bootstraps
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restart = true
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}
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if dc.RateLimit != nil {
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restart = restart || s.conf.Ratelimit != *dc.RateLimit
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s.conf.Ratelimit = *dc.RateLimit
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}
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if dc.EDNSCSEnabled != nil {
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s.conf.EnableEDNSClientSubnet = *dc.EDNSCSEnabled
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restart = true
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}
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if dc.CacheSize != nil {
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s.conf.CacheSize = *dc.CacheSize
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restart = true
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}
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if dc.CacheMinTTL != nil {
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s.conf.CacheMinTTL = *dc.CacheMinTTL
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restart = true
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}
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if dc.CacheMaxTTL != nil {
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s.conf.CacheMaxTTL = *dc.CacheMaxTTL
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restart = true
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}
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return restart
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}
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func (s *Server) setConfig(dc dnsConfig) (restart bool) {
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s.Lock()
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defer s.Unlock()
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if dc.ProtectionEnabled != nil {
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s.conf.ProtectionEnabled = *dc.ProtectionEnabled
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}
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if dc.BlockingMode != nil {
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s.conf.BlockingMode = *dc.BlockingMode
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if *dc.BlockingMode == "custom_ip" {
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s.conf.BlockingIPv4 = dc.BlockingIPv4.To4()
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s.conf.BlockingIPv6 = dc.BlockingIPv6.To16()
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}
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}
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if dc.DNSSECEnabled != nil {
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s.conf.EnableDNSSEC = *dc.DNSSECEnabled
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}
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if dc.DisableIPv6 != nil {
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s.conf.AAAADisabled = *dc.DisableIPv6
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}
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if dc.UpstreamMode != nil {
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s.conf.AllServers = *dc.UpstreamMode == "parallel"
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s.conf.FastestAddr = *dc.UpstreamMode == "fastest_addr"
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}
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if dc.ResolveClients != nil {
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s.conf.ResolveClients = *dc.ResolveClients
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}
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return s.setConfigRestartable(dc)
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}
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// upstreamJSON is a request body for handleTestUpstreamDNS endpoint.
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type upstreamJSON struct {
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Upstreams []string `json:"upstream_dns"`
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BootstrapDNS []string `json:"bootstrap_dns"`
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PrivateUpstreams []string `json:"private_upstream"`
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}
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// ValidateUpstreams validates each upstream and returns an error if any
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// upstream is invalid or if there are no default upstreams specified.
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//
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// TODO(e.burkov): Move into aghnet or even into dnsproxy.
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func ValidateUpstreams(upstreams []string) (err error) {
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// No need to validate comments
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upstreams = filterOutComments(upstreams)
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// Consider this case valid because defaultDNS will be used
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if len(upstreams) == 0 {
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return nil
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}
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_, err = proxy.ParseUpstreamsConfig(
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upstreams,
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upstream.Options{
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Bootstrap: []string{},
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Timeout: DefaultTimeout,
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},
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)
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if err != nil {
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return err
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}
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var defaultUpstreamFound bool
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for _, u := range upstreams {
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var ok bool
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ok, err = validateUpstream(u)
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if err != nil {
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return err
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}
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if !defaultUpstreamFound {
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defaultUpstreamFound = ok
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}
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}
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if !defaultUpstreamFound {
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return fmt.Errorf("no default upstreams specified")
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}
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return nil
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}
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var protocols = []string{"tls://", "https://", "tcp://", "sdns://", "quic://"}
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func validateUpstream(u string) (bool, error) {
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// Check if the user tries to specify upstream for domain.
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u, useDefault, err := separateUpstream(u)
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if err != nil {
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return useDefault, err
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}
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// The special server address '#' means "use the default servers"
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if u == "#" && !useDefault {
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return useDefault, nil
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}
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// Check if the upstream has a valid protocol prefix
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for _, proto := range protocols {
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if strings.HasPrefix(u, proto) {
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return useDefault, nil
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}
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}
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// Return error if the upstream contains '://' without any valid protocol
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if strings.Contains(u, "://") {
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return useDefault, fmt.Errorf("wrong protocol")
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}
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// Check if upstream is valid plain DNS
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return useDefault, checkPlainDNS(u)
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}
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// separateUpstream returns the upstream without the specified domains.
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// useDefault is true when a default upstream must be used.
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func separateUpstream(upstreamStr string) (upstream string, useDefault bool, err error) {
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defer agherr.Annotate("bad upstream for domain spec %q: %w", &err, upstreamStr)
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if !strings.HasPrefix(upstreamStr, "[/") {
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return upstreamStr, true, nil
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}
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parts := strings.Split(upstreamStr[2:], "/]")
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if len(parts) != 2 {
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return "", false, agherr.Error("duplicated separator")
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}
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domains := parts[0]
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upstream = parts[1]
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for i, host := range strings.Split(domains, "/") {
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if host == "" {
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continue
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}
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err = aghnet.ValidateDomainName(host)
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if err != nil {
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return "", false, fmt.Errorf("domain at index %d: %w", i, err)
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}
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}
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return upstream, false, nil
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}
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// checkPlainDNS checks if host is plain DNS
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func checkPlainDNS(upstream string) error {
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// Check if host is ip without port
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if net.ParseIP(upstream) != nil {
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return nil
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}
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// Check if host is ip with port
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ip, port, err := net.SplitHostPort(upstream)
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if err != nil {
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return err
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}
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if net.ParseIP(ip) == nil {
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return fmt.Errorf("%s is not a valid IP", ip)
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}
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_, err = strconv.ParseInt(port, 0, 64)
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if err != nil {
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return fmt.Errorf("%s is not a valid port: %w", port, err)
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}
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return nil
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}
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// excFunc is a signature of function to check if upstream exchanges correctly.
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type excFunc func(u upstream.Upstream) (err error)
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// checkDNSUpstreamExc checks if the DNS upstream exchanges correctly.
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func checkDNSUpstreamExc(u upstream.Upstream) (err error) {
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req := &dns.Msg{
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MsgHdr: dns.MsgHdr{
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Id: dns.Id(),
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RecursionDesired: true,
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},
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Question: []dns.Question{{
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Name: "google-public-dns-a.google.com.",
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Qtype: dns.TypeA,
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Qclass: dns.ClassINET,
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}},
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}
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var reply *dns.Msg
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reply, err = u.Exchange(req)
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if err != nil {
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return fmt.Errorf("couldn't communicate with upstream: %w", err)
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}
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if len(reply.Answer) != 1 {
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return fmt.Errorf("wrong response")
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}
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if t, ok := reply.Answer[0].(*dns.A); ok {
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if !net.IPv4(8, 8, 8, 8).Equal(t.A) {
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return fmt.Errorf("wrong response")
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}
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}
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return nil
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}
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// checkPrivateUpstreamExc checks if the upstream for resolving private
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// addresses exchanges correctly.
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func checkPrivateUpstreamExc(u upstream.Upstream) (err error) {
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req := &dns.Msg{
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MsgHdr: dns.MsgHdr{
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Id: dns.Id(),
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RecursionDesired: true,
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},
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Question: []dns.Question{{
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Name: "1.0.0.127.in-addr.arpa.",
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Qtype: dns.TypePTR,
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Qclass: dns.ClassINET,
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}},
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}
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if _, err = u.Exchange(req); err != nil {
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return fmt.Errorf("couldn't communicate with upstream: %w", err)
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}
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return nil
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}
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func checkDNS(input string, bootstrap []string, ef excFunc) (err error) {
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if !isUpstream(input) {
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return nil
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}
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// Separate upstream from domains list.
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var useDefault bool
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if input, useDefault, err = separateUpstream(input); err != nil {
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return fmt.Errorf("wrong upstream format: %w", err)
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}
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// No need to check this DNS server.
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if !useDefault {
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return nil
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}
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if _, err = validateUpstream(input); err != nil {
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return fmt.Errorf("wrong upstream format: %w", err)
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}
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if len(bootstrap) == 0 {
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bootstrap = defaultBootstrap
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}
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log.Debug("checking if dns server %q works...", input)
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var u upstream.Upstream
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u, err = upstream.AddressToUpstream(input, upstream.Options{
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Bootstrap: bootstrap,
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Timeout: DefaultTimeout,
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})
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if err != nil {
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return fmt.Errorf("failed to choose upstream for %q: %w", input, err)
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}
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if err = ef(u); err != nil {
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return fmt.Errorf("upstream %q fails to exchange: %w", input, err)
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}
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log.Debug("dns %s works OK", input)
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return nil
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}
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|
|
func (s *Server) handleTestUpstreamDNS(w http.ResponseWriter, r *http.Request) {
|
|
req := &upstreamJSON{}
|
|
err := json.NewDecoder(r.Body).Decode(req)
|
|
if err != nil {
|
|
httpError(r, w, http.StatusBadRequest, "Failed to read request body: %s", err)
|
|
|
|
return
|
|
}
|
|
|
|
result := map[string]string{}
|
|
bootstraps := req.BootstrapDNS
|
|
|
|
for _, host := range req.Upstreams {
|
|
err = checkDNS(host, bootstraps, checkDNSUpstreamExc)
|
|
if err != nil {
|
|
log.Info("%v", err)
|
|
result[host] = err.Error()
|
|
|
|
continue
|
|
}
|
|
|
|
result[host] = "OK"
|
|
}
|
|
|
|
for _, host := range req.PrivateUpstreams {
|
|
err = checkDNS(host, bootstraps, checkPrivateUpstreamExc)
|
|
if err != nil {
|
|
log.Info("%v", err)
|
|
// TODO(e.burkov): If passed upstream have already
|
|
// written an error above, we rewriting the error for
|
|
// it. These cases should be handled properly instead.
|
|
result[host] = err.Error()
|
|
|
|
continue
|
|
}
|
|
|
|
result[host] = "OK"
|
|
}
|
|
|
|
jsonVal, err := json.Marshal(result)
|
|
if err != nil {
|
|
httpError(r, w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
|
|
|
|
return
|
|
}
|
|
|
|
w.Header().Set("Content-Type", "application/json")
|
|
_, err = w.Write(jsonVal)
|
|
if err != nil {
|
|
httpError(r, w, http.StatusInternalServerError, "Couldn't write body: %s", err)
|
|
|
|
return
|
|
}
|
|
}
|
|
|
|
// Control flow:
|
|
// web
|
|
// -> dnsforward.handleDOH -> dnsforward.ServeHTTP
|
|
// -> proxy.ServeHTTP -> proxy.handleDNSRequest
|
|
// -> dnsforward.handleDNSRequest
|
|
func (s *Server) handleDOH(w http.ResponseWriter, r *http.Request) {
|
|
if !s.conf.TLSAllowUnencryptedDOH && r.TLS == nil {
|
|
httpError(r, w, http.StatusNotFound, "Not Found")
|
|
return
|
|
}
|
|
|
|
if !s.IsRunning() {
|
|
httpError(r, w, http.StatusInternalServerError, "dns server is not running")
|
|
return
|
|
}
|
|
|
|
s.ServeHTTP(w, r)
|
|
}
|
|
|
|
func (s *Server) registerHandlers() {
|
|
s.conf.HTTPRegister(http.MethodGet, "/control/dns_info", s.handleGetConfig)
|
|
s.conf.HTTPRegister(http.MethodPost, "/control/dns_config", s.handleSetConfig)
|
|
s.conf.HTTPRegister(http.MethodPost, "/control/test_upstream_dns", s.handleTestUpstreamDNS)
|
|
|
|
s.conf.HTTPRegister(http.MethodGet, "/control/access/list", s.handleAccessList)
|
|
s.conf.HTTPRegister(http.MethodPost, "/control/access/set", s.handleAccessSet)
|
|
|
|
// Register both versions, with and without the trailing slash, to
|
|
// prevent a 301 Moved Permanently redirect when clients request the
|
|
// path without the trailing slash. Those redirects break some clients.
|
|
//
|
|
// See go doc net/http.ServeMux.
|
|
//
|
|
// See also https://github.com/AdguardTeam/AdGuardHome/issues/2628.
|
|
s.conf.HTTPRegister("", "/dns-query", s.handleDOH)
|
|
s.conf.HTTPRegister("", "/dns-query/", s.handleDOH)
|
|
}
|