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serve.go
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serve.go
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// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package embed
import (
"context"
"fmt"
"io"
defaultLog "log"
"math"
"net"
"net/http"
"strings"
"time"
etcdservergw "go.etcd.io/etcd/api/v3/etcdserverpb/gw"
"go.etcd.io/etcd/client/pkg/v3/transport"
"go.etcd.io/etcd/client/v3/credentials"
"go.etcd.io/etcd/pkg/v3/debugutil"
"go.etcd.io/etcd/pkg/v3/httputil"
"go.etcd.io/etcd/server/v3/etcdserver"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3client"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3election"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3election/v3electionpb"
v3electiongw "go.etcd.io/etcd/server/v3/etcdserver/api/v3election/v3electionpb/gw"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3lock"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3lock/v3lockpb"
v3lockgw "go.etcd.io/etcd/server/v3/etcdserver/api/v3lock/v3lockpb/gw"
"go.etcd.io/etcd/server/v3/etcdserver/api/v3rpc"
gw "github.com/grpc-ecosystem/grpc-gateway/runtime"
"github.com/soheilhy/cmux"
"github.com/tmc/grpc-websocket-proxy/wsproxy"
"go.uber.org/zap"
"golang.org/x/net/trace"
"google.golang.org/grpc"
)
type serveCtx struct {
lg *zap.Logger
l net.Listener
addr string
network string
secure bool
insecure bool
ctx context.Context
cancel context.CancelFunc
userHandlers map[string]http.Handler
serviceRegister func(*grpc.Server)
serversC chan *servers
}
type servers struct {
secure bool
grpc *grpc.Server
http *http.Server
}
func newServeCtx(lg *zap.Logger) *serveCtx {
ctx, cancel := context.WithCancel(context.Background())
if lg == nil {
lg = zap.NewNop()
}
return &serveCtx{
lg: lg,
ctx: ctx,
cancel: cancel,
userHandlers: make(map[string]http.Handler),
serversC: make(chan *servers, 2), // in case sctx.insecure,sctx.secure true
}
}
// serve accepts incoming connections on the listener l,
// creating a new service goroutine for each. The service goroutines
// read requests and then call handler to reply to them.
func (sctx *serveCtx) serve(
s *etcdserver.EtcdServer,
tlsinfo *transport.TLSInfo,
handler http.Handler,
errHandler func(error),
gopts ...grpc.ServerOption) (err error) {
logger := defaultLog.New(io.Discard, "etcdhttp", 0)
// When the quorum isn't satisfied, then etcd server will be blocked
// on <-s.ReadyNotify(). Set a timeout here so that the etcd server
// can continue to serve serializable read request.
select {
case <-time.After(s.Cfg.WaitClusterReadyTimeout):
sctx.lg.Warn("timed out waiting for the ready notification")
case <-s.ReadyNotify():
}
sctx.lg.Info("ready to serve client requests")
m := cmux.New(sctx.l)
v3c := v3client.New(s)
servElection := v3election.NewElectionServer(v3c)
servLock := v3lock.NewLockServer(v3c)
var gs *grpc.Server
defer func() {
if err != nil && gs != nil {
gs.Stop()
}
}()
if sctx.insecure {
gs = v3rpc.Server(s, nil, nil, gopts...)
v3electionpb.RegisterElectionServer(gs, servElection)
v3lockpb.RegisterLockServer(gs, servLock)
if sctx.serviceRegister != nil {
sctx.serviceRegister(gs)
}
grpcl := m.Match(cmux.HTTP2())
go func() { errHandler(gs.Serve(grpcl)) }()
var gwmux *gw.ServeMux
if s.Cfg.EnableGRPCGateway {
gwmux, err = sctx.registerGateway([]grpc.DialOption{grpc.WithInsecure()})
if err != nil {
return err
}
}
httpmux := sctx.createMux(gwmux, handler)
srvhttp := &http.Server{
Handler: createAccessController(sctx.lg, s, httpmux),
ErrorLog: logger, // do not log user error
}
httpl := m.Match(cmux.HTTP1())
go func() { errHandler(srvhttp.Serve(httpl)) }()
sctx.serversC <- &servers{grpc: gs, http: srvhttp}
sctx.lg.Info(
"serving client traffic insecurely; this is strongly discouraged!",
zap.String("address", sctx.l.Addr().String()),
)
}
if sctx.secure {
tlscfg, tlsErr := tlsinfo.ServerConfig()
if tlsErr != nil {
return tlsErr
}
gs = v3rpc.Server(s, tlscfg, nil, gopts...)
v3electionpb.RegisterElectionServer(gs, servElection)
v3lockpb.RegisterLockServer(gs, servLock)
if sctx.serviceRegister != nil {
sctx.serviceRegister(gs)
}
handler = grpcHandlerFunc(gs, handler)
var gwmux *gw.ServeMux
if s.Cfg.EnableGRPCGateway {
dtls := tlscfg.Clone()
// trust local server
dtls.InsecureSkipVerify = true
bundle := credentials.NewBundle(credentials.Config{TLSConfig: dtls})
opts := []grpc.DialOption{grpc.WithTransportCredentials(bundle.TransportCredentials())}
gwmux, err = sctx.registerGateway(opts)
if err != nil {
return err
}
}
var tlsl net.Listener
tlsl, err = transport.NewTLSListener(m.Match(cmux.Any()), tlsinfo)
if err != nil {
return err
}
// TODO: add debug flag; enable logging when debug flag is set
httpmux := sctx.createMux(gwmux, handler)
srv := &http.Server{
Handler: createAccessController(sctx.lg, s, httpmux),
TLSConfig: tlscfg,
ErrorLog: logger, // do not log user error
}
go func() { errHandler(srv.Serve(tlsl)) }()
sctx.serversC <- &servers{secure: true, grpc: gs, http: srv}
sctx.lg.Info(
"serving client traffic securely",
zap.String("address", sctx.l.Addr().String()),
)
}
close(sctx.serversC)
return m.Serve()
}
// grpcHandlerFunc returns an http.Handler that delegates to grpcServer on incoming gRPC
// connections or otherHandler otherwise. Given in gRPC docs.
func grpcHandlerFunc(grpcServer *grpc.Server, otherHandler http.Handler) http.Handler {
if otherHandler == nil {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
grpcServer.ServeHTTP(w, r)
})
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.ProtoMajor == 2 && strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
grpcServer.ServeHTTP(w, r)
} else {
otherHandler.ServeHTTP(w, r)
}
})
}
type registerHandlerFunc func(context.Context, *gw.ServeMux, *grpc.ClientConn) error
func (sctx *serveCtx) registerGateway(opts []grpc.DialOption) (*gw.ServeMux, error) {
ctx := sctx.ctx
addr := sctx.addr
if network := sctx.network; network == "unix" {
// explicitly define unix network for gRPC socket support
addr = fmt.Sprintf("%s://%s", network, addr)
}
opts = append(opts, grpc.WithDefaultCallOptions([]grpc.CallOption{
grpc.MaxCallRecvMsgSize(math.MaxInt32),
}...))
conn, err := grpc.DialContext(ctx, addr, opts...)
if err != nil {
return nil, err
}
gwmux := gw.NewServeMux()
handlers := []registerHandlerFunc{
etcdservergw.RegisterKVHandler,
etcdservergw.RegisterWatchHandler,
etcdservergw.RegisterLeaseHandler,
etcdservergw.RegisterClusterHandler,
etcdservergw.RegisterMaintenanceHandler,
etcdservergw.RegisterAuthHandler,
v3lockgw.RegisterLockHandler,
v3electiongw.RegisterElectionHandler,
}
for _, h := range handlers {
if err := h(ctx, gwmux, conn); err != nil {
return nil, err
}
}
go func() {
<-ctx.Done()
if cerr := conn.Close(); cerr != nil {
sctx.lg.Warn(
"failed to close connection",
zap.String("address", sctx.l.Addr().String()),
zap.Error(cerr),
)
}
}()
return gwmux, nil
}
func (sctx *serveCtx) createMux(gwmux *gw.ServeMux, handler http.Handler) *http.ServeMux {
httpmux := http.NewServeMux()
for path, h := range sctx.userHandlers {
httpmux.Handle(path, h)
}
if gwmux != nil {
httpmux.Handle(
"/v3/",
wsproxy.WebsocketProxy(
gwmux,
wsproxy.WithRequestMutator(
// Default to the POST method for streams
func(_ *http.Request, outgoing *http.Request) *http.Request {
outgoing.Method = "POST"
return outgoing
},
),
wsproxy.WithMaxRespBodyBufferSize(0x7fffffff),
),
)
}
if handler != nil {
httpmux.Handle("/", handler)
}
return httpmux
}
// createAccessController wraps HTTP multiplexer:
// - mutate gRPC gateway request paths
// - check hostname whitelist
// client HTTP requests goes here first
func createAccessController(lg *zap.Logger, s *etcdserver.EtcdServer, mux *http.ServeMux) http.Handler {
if lg == nil {
lg = zap.NewNop()
}
return &accessController{lg: lg, s: s, mux: mux}
}
type accessController struct {
lg *zap.Logger
s *etcdserver.EtcdServer
mux *http.ServeMux
}
func (ac *accessController) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
if req == nil {
http.Error(rw, "Request is nil", http.StatusBadRequest)
return
}
// redirect for backward compatibilities
if req.URL != nil && strings.HasPrefix(req.URL.Path, "/v3beta/") {
req.URL.Path = strings.Replace(req.URL.Path, "/v3beta/", "/v3/", 1)
}
if req.TLS == nil { // check origin if client connection is not secure
host := httputil.GetHostname(req)
if !ac.s.AccessController.IsHostWhitelisted(host) {
ac.lg.Warn(
"rejecting HTTP request to prevent DNS rebinding attacks",
zap.String("host", host),
)
http.Error(rw, errCVE20185702(host), http.StatusMisdirectedRequest)
return
}
} else if ac.s.Cfg.ClientCertAuthEnabled && ac.s.Cfg.EnableGRPCGateway &&
ac.s.AuthStore().IsAuthEnabled() && strings.HasPrefix(req.URL.Path, "/v3/") {
for _, chains := range req.TLS.VerifiedChains {
if len(chains) < 1 {
continue
}
if len(chains[0].Subject.CommonName) != 0 {
http.Error(rw, "CommonName of client sending a request against gateway will be ignored and not used as expected", http.StatusBadRequest)
return
}
}
}
// Write CORS header.
if ac.s.AccessController.OriginAllowed("*") {
addCORSHeader(rw, "*")
} else if origin := req.Header.Get("Origin"); ac.s.OriginAllowed(origin) {
addCORSHeader(rw, origin)
}
if req.Method == "OPTIONS" {
rw.WriteHeader(http.StatusOK)
return
}
ac.mux.ServeHTTP(rw, req)
}
// addCORSHeader adds the correct cors headers given an origin
func addCORSHeader(w http.ResponseWriter, origin string) {
w.Header().Add("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
w.Header().Add("Access-Control-Allow-Origin", origin)
w.Header().Add("Access-Control-Allow-Headers", "accept, content-type, authorization")
}
// https://github.com/transmission/transmission/pull/468
func errCVE20185702(host string) string {
return fmt.Sprintf(`
etcd received your request, but the Host header was unrecognized.
To fix this, choose one of the following options:
- Enable TLS, then any HTTPS request will be allowed.
- Add the hostname you want to use to the whitelist in settings.
- e.g. etcd --host-whitelist %q
This requirement has been added to help prevent "DNS Rebinding" attacks (CVE-2018-5702).
`, host)
}
// WrapCORS wraps existing handler with CORS.
// TODO: deprecate this after v2 proxy deprecate
func WrapCORS(cors map[string]struct{}, h http.Handler) http.Handler {
return &corsHandler{
ac: &etcdserver.AccessController{CORS: cors},
h: h,
}
}
type corsHandler struct {
ac *etcdserver.AccessController
h http.Handler
}
func (ch *corsHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
if ch.ac.OriginAllowed("*") {
addCORSHeader(rw, "*")
} else if origin := req.Header.Get("Origin"); ch.ac.OriginAllowed(origin) {
addCORSHeader(rw, origin)
}
if req.Method == "OPTIONS" {
rw.WriteHeader(http.StatusOK)
return
}
ch.h.ServeHTTP(rw, req)
}
func (sctx *serveCtx) registerUserHandler(s string, h http.Handler) {
if sctx.userHandlers[s] != nil {
sctx.lg.Warn("path is already registered by user handler", zap.String("path", s))
return
}
sctx.userHandlers[s] = h
}
func (sctx *serveCtx) registerPprof() {
for p, h := range debugutil.PProfHandlers() {
sctx.registerUserHandler(p, h)
}
}
func (sctx *serveCtx) registerTrace() {
reqf := func(w http.ResponseWriter, r *http.Request) { trace.Render(w, r, true) }
sctx.registerUserHandler("/debug/requests", http.HandlerFunc(reqf))
evf := func(w http.ResponseWriter, r *http.Request) { trace.RenderEvents(w, r, true) }
sctx.registerUserHandler("/debug/events", http.HandlerFunc(evf))
}