AdGuardHome/dnsforward/dnsforward_http.go

470 lines
12 KiB
Go

package dnsforward
import (
"encoding/json"
"fmt"
"net"
"net/http"
"strconv"
"strings"
"github.com/AdguardTeam/dnsproxy/upstream"
"github.com/AdguardTeam/golibs/jsonutil"
"github.com/AdguardTeam/golibs/log"
"github.com/AdguardTeam/golibs/utils"
"github.com/miekg/dns"
)
func httpError(r *http.Request, w http.ResponseWriter, code int, format string, args ...interface{}) {
text := fmt.Sprintf(format, args...)
log.Info("DNS: %s %s: %s", r.Method, r.URL, text)
http.Error(w, text, code)
}
type dnsConfigJSON struct {
Upstreams []string `json:"upstream_dns"`
Bootstraps []string `json:"bootstrap_dns"`
ProtectionEnabled bool `json:"protection_enabled"`
RateLimit uint32 `json:"ratelimit"`
BlockingMode string `json:"blocking_mode"`
BlockingIPv4 string `json:"blocking_ipv4"`
BlockingIPv6 string `json:"blocking_ipv6"`
EDNSCSEnabled bool `json:"edns_cs_enabled"`
DNSSECEnabled bool `json:"dnssec_enabled"`
DisableIPv6 bool `json:"disable_ipv6"`
UpstreamMode string `json:"upstream_mode"`
CacheSize uint32 `json:"cache_size"`
CacheMinTTL uint32 `json:"cache_ttl_min"`
CacheMaxTTL uint32 `json:"cache_ttl_max"`
}
func (s *Server) handleGetConfig(w http.ResponseWriter, r *http.Request) {
resp := dnsConfigJSON{}
s.RLock()
resp.Upstreams = stringArrayDup(s.conf.UpstreamDNS)
resp.Bootstraps = stringArrayDup(s.conf.BootstrapDNS)
resp.ProtectionEnabled = s.conf.ProtectionEnabled
resp.BlockingMode = s.conf.BlockingMode
resp.BlockingIPv4 = s.conf.BlockingIPv4
resp.BlockingIPv6 = s.conf.BlockingIPv6
resp.RateLimit = s.conf.Ratelimit
resp.EDNSCSEnabled = s.conf.EnableEDNSClientSubnet
resp.DNSSECEnabled = s.conf.EnableDNSSEC
resp.DisableIPv6 = s.conf.AAAADisabled
resp.CacheSize = s.conf.CacheSize
resp.CacheMinTTL = s.conf.CacheMinTTL
resp.CacheMaxTTL = s.conf.CacheMaxTTL
if s.conf.FastestAddr {
resp.UpstreamMode = "fastest_addr"
} else if s.conf.AllServers {
resp.UpstreamMode = "parallel"
}
s.RUnlock()
js, err := json.Marshal(resp)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "json.Marshal: %s", err)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = w.Write(js)
}
func checkBlockingMode(req dnsConfigJSON) bool {
bm := req.BlockingMode
if !(bm == "default" || bm == "nxdomain" || bm == "null_ip" || bm == "custom_ip") {
return false
}
if bm == "custom_ip" {
ip := net.ParseIP(req.BlockingIPv4)
if ip == nil || ip.To4() == nil {
return false
}
ip = net.ParseIP(req.BlockingIPv6)
if ip == nil {
return false
}
}
return true
}
// Validate bootstrap server address
func checkBootstrap(addr string) error {
if addr == "" { // additional check is required because NewResolver() allows empty address
return fmt.Errorf("invalid bootstrap server address: empty")
}
_, err := upstream.NewResolver(addr, 0)
if err != nil {
return fmt.Errorf("invalid bootstrap server address: %s", err)
}
return nil
}
// nolint(gocyclo) - we need to check each JSON field separately
func (s *Server) handleSetConfig(w http.ResponseWriter, r *http.Request) {
req := dnsConfigJSON{}
js, err := jsonutil.DecodeObject(&req, r.Body)
if err != nil {
httpError(r, w, http.StatusBadRequest, "json.Decode: %s", err)
return
}
if js.Exists("upstream_dns") {
if len(req.Upstreams) != 0 {
err = ValidateUpstreams(req.Upstreams)
if err != nil {
httpError(r, w, http.StatusBadRequest, "wrong upstreams specification: %s", err)
return
}
}
}
if js.Exists("bootstrap_dns") {
for _, boot := range req.Bootstraps {
if err := checkBootstrap(boot); err != nil {
httpError(r, w, http.StatusBadRequest, "%s can not be used as bootstrap dns cause: %s", boot, err)
return
}
}
}
if js.Exists("blocking_mode") && !checkBlockingMode(req) {
httpError(r, w, http.StatusBadRequest, "blocking_mode: incorrect value")
return
}
if js.Exists("upstream_mode") &&
!(req.UpstreamMode == "" || req.UpstreamMode == "fastest_addr" || req.UpstreamMode == "parallel") {
httpError(r, w, http.StatusBadRequest, "upstream_mode: incorrect value")
return
}
if req.CacheMinTTL > req.CacheMaxTTL {
httpError(r, w, http.StatusBadRequest, "cache_ttl_min must be less or equal than cache_ttl_max")
return
}
restart := false
s.Lock()
if js.Exists("upstream_dns") {
s.conf.UpstreamDNS = req.Upstreams
restart = true
}
if js.Exists("bootstrap_dns") {
s.conf.BootstrapDNS = req.Bootstraps
restart = true
}
if js.Exists("protection_enabled") {
s.conf.ProtectionEnabled = req.ProtectionEnabled
}
if js.Exists("blocking_mode") {
s.conf.BlockingMode = req.BlockingMode
if req.BlockingMode == "custom_ip" {
if js.Exists("blocking_ipv4") {
s.conf.BlockingIPv4 = req.BlockingIPv4
s.conf.BlockingIPAddrv4 = net.ParseIP(req.BlockingIPv4)
}
if js.Exists("blocking_ipv6") {
s.conf.BlockingIPv6 = req.BlockingIPv6
s.conf.BlockingIPAddrv6 = net.ParseIP(req.BlockingIPv6)
}
}
}
if js.Exists("ratelimit") {
if s.conf.Ratelimit != req.RateLimit {
restart = true
}
s.conf.Ratelimit = req.RateLimit
}
if js.Exists("edns_cs_enabled") {
s.conf.EnableEDNSClientSubnet = req.EDNSCSEnabled
restart = true
}
if js.Exists("dnssec_enabled") {
s.conf.EnableDNSSEC = req.DNSSECEnabled
}
if js.Exists("disable_ipv6") {
s.conf.AAAADisabled = req.DisableIPv6
}
if js.Exists("cache_size") {
s.conf.CacheSize = req.CacheSize
restart = true
}
if js.Exists("cache_ttl_min") {
s.conf.CacheMinTTL = req.CacheMinTTL
restart = true
}
if js.Exists("cache_ttl_max") {
s.conf.CacheMaxTTL = req.CacheMaxTTL
restart = true
}
if js.Exists("upstream_mode") {
s.conf.FastestAddr = false
s.conf.AllServers = false
switch req.UpstreamMode {
case "":
//
case "parallel":
s.conf.AllServers = true
case "fastest_addr":
s.conf.FastestAddr = true
}
}
s.Unlock()
s.conf.ConfigModified()
if restart {
err = s.Reconfigure(nil)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "%s", err)
return
}
}
}
type upstreamJSON struct {
Upstreams []string `json:"upstream_dns"` // Upstreams
BootstrapDNS []string `json:"bootstrap_dns"` // Bootstrap DNS
}
// ValidateUpstreams validates each upstream and returns an error if any upstream is invalid or if there are no default upstreams specified
func ValidateUpstreams(upstreams []string) error {
var defaultUpstreamFound bool
for _, u := range upstreams {
d, err := validateUpstream(u)
if err != nil {
return err
}
// Check this flag until default upstream will not be found
if !defaultUpstreamFound {
defaultUpstreamFound = d
}
}
// Return error if there are no default upstreams
if !defaultUpstreamFound {
return fmt.Errorf("no default upstreams specified")
}
return nil
}
var protocols = []string{"tls://", "https://", "tcp://", "sdns://"}
func validateUpstream(u string) (bool, error) {
// Check if user tries to specify upstream for domain
u, defaultUpstream, err := separateUpstream(u)
if err != nil {
return defaultUpstream, err
}
// The special server address '#' means "use the default servers"
if u == "#" && !defaultUpstream {
return defaultUpstream, nil
}
// Check if the upstream has a valid protocol prefix
for _, proto := range protocols {
if strings.HasPrefix(u, proto) {
return defaultUpstream, nil
}
}
// Return error if the upstream contains '://' without any valid protocol
if strings.Contains(u, "://") {
return defaultUpstream, fmt.Errorf("wrong protocol")
}
// Check if upstream is valid plain DNS
return defaultUpstream, checkPlainDNS(u)
}
// separateUpstream returns upstream without specified domains and a bool flag that indicates if no domains were specified
// error will be returned if upstream per domain specification is invalid
func separateUpstream(upstream string) (string, bool, error) {
defaultUpstream := true
if strings.HasPrefix(upstream, "[/") {
defaultUpstream = false
// split domains and upstream string
domainsAndUpstream := strings.Split(strings.TrimPrefix(upstream, "[/"), "/]")
if len(domainsAndUpstream) != 2 {
return "", defaultUpstream, fmt.Errorf("wrong DNS upstream per domain specification: %s", upstream)
}
// split domains list and validate each one
for _, host := range strings.Split(domainsAndUpstream[0], "/") {
if host != "" {
if err := utils.IsValidHostname(host); err != nil {
return "", defaultUpstream, err
}
}
}
upstream = domainsAndUpstream[1]
}
return upstream, defaultUpstream, nil
}
// checkPlainDNS checks if host is plain DNS
func checkPlainDNS(upstream string) error {
// Check if host is ip without port
if net.ParseIP(upstream) != nil {
return nil
}
// Check if host is ip with port
ip, port, err := net.SplitHostPort(upstream)
if err != nil {
return err
}
if net.ParseIP(ip) == nil {
return fmt.Errorf("%s is not a valid IP", ip)
}
_, err = strconv.ParseInt(port, 0, 64)
if err != nil {
return fmt.Errorf("%s is not a valid port: %s", port, err)
}
return nil
}
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
}
if len(req.Upstreams) == 0 {
httpError(r, w, http.StatusBadRequest, "No servers specified")
return
}
result := map[string]string{}
for _, host := range req.Upstreams {
err = checkDNS(host, req.BootstrapDNS)
if err != nil {
log.Info("%v", err)
result[host] = err.Error()
} else {
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
}
}
func checkDNS(input string, bootstrap []string) error {
// separate upstream from domains list
input, defaultUpstream, err := separateUpstream(input)
if err != nil {
return fmt.Errorf("wrong upstream format: %s", err)
}
// No need to check this DNS server
if input == "#" || !defaultUpstream {
return nil
}
if _, err := validateUpstream(input); err != nil {
return fmt.Errorf("wrong upstream format: %s", err)
}
if len(bootstrap) == 0 {
bootstrap = defaultBootstrap
}
log.Debug("Checking if DNS %s works...", input)
u, err := upstream.AddressToUpstream(input, upstream.Options{Bootstrap: bootstrap, Timeout: DefaultTimeout})
if err != nil {
return fmt.Errorf("failed to choose upstream for %s: %s", input, err)
}
req := dns.Msg{}
req.Id = dns.Id()
req.RecursionDesired = true
req.Question = []dns.Question{
{Name: "google-public-dns-a.google.com.", Qtype: dns.TypeA, Qclass: dns.ClassINET},
}
reply, err := u.Exchange(&req)
if err != nil {
return fmt.Errorf("couldn't communicate with DNS server %s: %s", input, err)
}
if len(reply.Answer) != 1 {
return fmt.Errorf("DNS server %s returned wrong answer", input)
}
if t, ok := reply.Answer[0].(*dns.A); ok {
if !net.IPv4(8, 8, 8, 8).Equal(t.A) {
return fmt.Errorf("DNS server %s returned wrong answer: %v", input, t.A)
}
}
log.Debug("DNS %s works OK", input)
return nil
}
// 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("GET", "/control/dns_info", s.handleGetConfig)
s.conf.HTTPRegister("POST", "/control/dns_config", s.handleSetConfig)
s.conf.HTTPRegister("POST", "/control/test_upstream_dns", s.handleTestUpstreamDNS)
s.conf.HTTPRegister("GET", "/control/access/list", s.handleAccessList)
s.conf.HTTPRegister("POST", "/control/access/set", s.handleAccessSet)
s.conf.HTTPRegister("", "/dns-query", s.handleDOH)
}