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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 rafthttp
import (
"context"
"errors"
"fmt"
"io/ioutil"
"net/http"
"path"
"strings"
pioutil "github.com/coreos/etcd/pkg/ioutil"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/snap"
"github.com/coreos/etcd/version"
)
const (
// connReadLimitByte limits the number of bytes
// a single read can read out.
//
// 64KB should be large enough for not causing
// throughput bottleneck as well as small enough
// for not causing a read timeout.
connReadLimitByte = 64 * 1024
)
var (
RaftPrefix = "/raft"
ProbingPrefix = path.Join(RaftPrefix, "probing")
RaftStreamPrefix = path.Join(RaftPrefix, "stream")
RaftSnapshotPrefix = path.Join(RaftPrefix, "snapshot")
errIncompatibleVersion = errors.New("incompatible version")
errClusterIDMismatch = errors.New("cluster ID mismatch")
)
type peerGetter interface {
Get(id types.ID) Peer
}
type writerToResponse interface {
WriteTo(w http.ResponseWriter)
}
type pipelineHandler struct {
tr Transporter
r Raft
cid types.ID
}
// newPipelineHandler returns a handler for handling raft messages
// from pipeline for RaftPrefix.
//
// The handler reads out the raft message from request body,
// and forwards it to the given raft state machine for processing.
func newPipelineHandler(tr Transporter, r Raft, cid types.ID) http.Handler {
return &pipelineHandler{
tr: tr,
r: r,
cid: cid,
}
}
func (h *pipelineHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
w.Header().Set("Allow", "POST")
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
return
}
w.Header().Set("X-Etcd-Cluster-ID", h.cid.String())
if err := checkClusterCompatibilityFromHeader(r.Header, h.cid); err != nil {
http.Error(w, err.Error(), http.StatusPreconditionFailed)
return
}
addRemoteFromRequest(h.tr, r)
// Limit the data size that could be read from the request body, which ensures that read from
// connection will not time out accidentally due to possible blocking in underlying implementation.
limitedr := pioutil.NewLimitedBufferReader(r.Body, connReadLimitByte)
b, err := ioutil.ReadAll(limitedr)
if err != nil {
plog.Errorf("failed to read raft message (%v)", err)
http.Error(w, "error reading raft message", http.StatusBadRequest)
recvFailures.WithLabelValues(r.RemoteAddr).Inc()
return
}
var m raftpb.Message
if err := m.Unmarshal(b); err != nil {
plog.Errorf("failed to unmarshal raft message (%v)", err)
http.Error(w, "error unmarshaling raft message", http.StatusBadRequest)
recvFailures.WithLabelValues(r.RemoteAddr).Inc()
return
}
receivedBytes.WithLabelValues(types.ID(m.From).String()).Add(float64(len(b)))
if err := h.r.Process(context.TODO(), m); err != nil {
switch v := err.(type) {
case writerToResponse:
v.WriteTo(w)
default:
plog.Warningf("failed to process raft message (%v)", err)
http.Error(w, "error processing raft message", http.StatusInternalServerError)
w.(http.Flusher).Flush()
// disconnect the http stream
panic(err)
}
return
}
// Write StatusNoContent header after the message has been processed by
// raft, which facilitates the client to report MsgSnap status.
w.WriteHeader(http.StatusNoContent)
}
type snapshotHandler struct {
tr Transporter
r Raft
snapshotter *snap.Snapshotter
cid types.ID
}
func newSnapshotHandler(tr Transporter, r Raft, snapshotter *snap.Snapshotter, cid types.ID) http.Handler {
return &snapshotHandler{
tr: tr,
r: r,
snapshotter: snapshotter,
cid: cid,
}
}
// ServeHTTP serves HTTP request to receive and process snapshot message.
//
// If request sender dies without closing underlying TCP connection,
// the handler will keep waiting for the request body until TCP keepalive
// finds out that the connection is broken after several minutes.
// This is acceptable because
// 1. snapshot messages sent through other TCP connections could still be
// received and processed.
// 2. this case should happen rarely, so no further optimization is done.
func (h *snapshotHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
w.Header().Set("Allow", "POST")
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
return
}
w.Header().Set("X-Etcd-Cluster-ID", h.cid.String())
if err := checkClusterCompatibilityFromHeader(r.Header, h.cid); err != nil {
http.Error(w, err.Error(), http.StatusPreconditionFailed)
return
}
addRemoteFromRequest(h.tr, r)
dec := &messageDecoder{r: r.Body}
// let snapshots be very large since they can exceed 512MB for large installations
m, err := dec.decodeLimit(uint64(1 << 63))
if err != nil {
msg := fmt.Sprintf("failed to decode raft message (%v)", err)
plog.Errorf(msg)
http.Error(w, msg, http.StatusBadRequest)
recvFailures.WithLabelValues(r.RemoteAddr).Inc()
return
}
receivedBytes.WithLabelValues(types.ID(m.From).String()).Add(float64(m.Size()))
if m.Type != raftpb.MsgSnap {
plog.Errorf("unexpected raft message type %s on snapshot path", m.Type)
http.Error(w, "wrong raft message type", http.StatusBadRequest)
return
}
plog.Infof("receiving database snapshot [index:%d, from %s] ...", m.Snapshot.Metadata.Index, types.ID(m.From))
// save incoming database snapshot.
n, err := h.snapshotter.SaveDBFrom(r.Body, m.Snapshot.Metadata.Index)
if err != nil {
msg := fmt.Sprintf("failed to save KV snapshot (%v)", err)
plog.Error(msg)
http.Error(w, msg, http.StatusInternalServerError)
return
}
receivedBytes.WithLabelValues(types.ID(m.From).String()).Add(float64(n))
plog.Infof("received and saved database snapshot [index: %d, from: %s] successfully", m.Snapshot.Metadata.Index, types.ID(m.From))
if err := h.r.Process(context.TODO(), m); err != nil {
switch v := err.(type) {
// Process may return writerToResponse error when doing some
// additional checks before calling raft.Node.Step.
case writerToResponse:
v.WriteTo(w)
default:
msg := fmt.Sprintf("failed to process raft message (%v)", err)
plog.Warningf(msg)
http.Error(w, msg, http.StatusInternalServerError)
}
return
}
// Write StatusNoContent header after the message has been processed by
// raft, which facilitates the client to report MsgSnap status.
w.WriteHeader(http.StatusNoContent)
}
type streamHandler struct {
tr *Transport
peerGetter peerGetter
r Raft
id types.ID
cid types.ID
}
func newStreamHandler(tr *Transport, pg peerGetter, r Raft, id, cid types.ID) http.Handler {
return &streamHandler{
tr: tr,
peerGetter: pg,
r: r,
id: id,
cid: cid,
}
}
func (h *streamHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.Method != "GET" {
w.Header().Set("Allow", "GET")
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
return
}
w.Header().Set("X-Server-Version", version.Version)
w.Header().Set("X-Etcd-Cluster-ID", h.cid.String())
if err := checkClusterCompatibilityFromHeader(r.Header, h.cid); err != nil {
http.Error(w, err.Error(), http.StatusPreconditionFailed)
return
}
var t streamType
switch path.Dir(r.URL.Path) {
case streamTypeMsgAppV2.endpoint():
t = streamTypeMsgAppV2
case streamTypeMessage.endpoint():
t = streamTypeMessage
default:
plog.Debugf("ignored unexpected streaming request path %s", r.URL.Path)
http.Error(w, "invalid path", http.StatusNotFound)
return
}
fromStr := path.Base(r.URL.Path)
from, err := types.IDFromString(fromStr)
if err != nil {
plog.Errorf("failed to parse from %s into ID (%v)", fromStr, err)
http.Error(w, "invalid from", http.StatusNotFound)
return
}
if h.r.IsIDRemoved(uint64(from)) {
plog.Warningf("rejected the stream from peer %s since it was removed", from)
http.Error(w, "removed member", http.StatusGone)
return
}
p := h.peerGetter.Get(from)
if p == nil {
// This may happen in following cases:
// 1. user starts a remote peer that belongs to a different cluster
// with the same cluster ID.
// 2. local etcd falls behind of the cluster, and cannot recognize
// the members that joined after its current progress.
if urls := r.Header.Get("X-PeerURLs"); urls != "" {
h.tr.AddRemote(from, strings.Split(urls, ","))
}
plog.Errorf("failed to find member %s in cluster %s", from, h.cid)
http.Error(w, "error sender not found", http.StatusNotFound)
return
}
wto := h.id.String()
if gto := r.Header.Get("X-Raft-To"); gto != wto {
plog.Errorf("streaming request ignored (ID mismatch got %s want %s)", gto, wto)
http.Error(w, "to field mismatch", http.StatusPreconditionFailed)
return
}
w.WriteHeader(http.StatusOK)
w.(http.Flusher).Flush()
c := newCloseNotifier()
conn := &outgoingConn{
t: t,
Writer: w,
Flusher: w.(http.Flusher),
Closer: c,
}
p.attachOutgoingConn(conn)
<-c.closeNotify()
}
// checkClusterCompatibilityFromHeader checks the cluster compatibility of
// the local member from the given header.
// It checks whether the version of local member is compatible with
// the versions in the header, and whether the cluster ID of local member
// matches the one in the header.
func checkClusterCompatibilityFromHeader(header http.Header, cid types.ID) error {
if err := checkVersionCompability(header.Get("X-Server-From"), serverVersion(header), minClusterVersion(header)); err != nil {
plog.Errorf("request version incompatibility (%v)", err)
return errIncompatibleVersion
}
if gcid := header.Get("X-Etcd-Cluster-ID"); gcid != cid.String() {
plog.Errorf("request cluster ID mismatch (got %s want %s)", gcid, cid)
return errClusterIDMismatch
}
return nil
}
type closeNotifier struct {
done chan struct{}
}
func newCloseNotifier() *closeNotifier {
return &closeNotifier{
done: make(chan struct{}),
}
}
func (n *closeNotifier) Close() error {
close(n.done)
return nil
}
func (n *closeNotifier) closeNotify() <-chan struct{} { return n.done }
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