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util.go
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util.go
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// Copyright 2015 CoreOS, Inc.
//
// 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 (
"encoding/binary"
"fmt"
"io"
"net/http"
"net/url"
"strings"
"github.com/coreos/etcd/Godeps/_workspace/src/github.com/coreos/go-semver/semver"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/version"
)
var errMemberRemoved = fmt.Errorf("the member has been permanently removed from the cluster")
func writeEntryTo(w io.Writer, ent *raftpb.Entry) error {
size := ent.Size()
if err := binary.Write(w, binary.BigEndian, uint64(size)); err != nil {
return err
}
b, err := ent.Marshal()
if err != nil {
return err
}
_, err = w.Write(b)
return err
}
func readEntryFrom(r io.Reader, ent *raftpb.Entry) error {
var l uint64
if err := binary.Read(r, binary.BigEndian, &l); err != nil {
return err
}
buf := make([]byte, int(l))
if _, err := io.ReadFull(r, buf); err != nil {
return err
}
return ent.Unmarshal(buf)
}
// createPostRequest creates a HTTP POST request that sends raft message.
func createPostRequest(u url.URL, path string, body io.Reader, ct string, from, cid types.ID) *http.Request {
uu := u
uu.Path = path
req, err := http.NewRequest("POST", uu.String(), body)
if err != nil {
plog.Panicf("unexpected new request error (%v)", err)
}
req.Header.Set("Content-Type", ct)
req.Header.Set("X-Server-From", from.String())
req.Header.Set("X-Server-Version", version.Version)
req.Header.Set("X-Min-Cluster-Version", version.MinClusterVersion)
req.Header.Set("X-Etcd-Cluster-ID", cid.String())
return req
}
// checkPostResponse checks the response of the HTTP POST request that sends
// raft message.
func checkPostResponse(resp *http.Response, body []byte, req *http.Request, to types.ID) error {
switch resp.StatusCode {
case http.StatusPreconditionFailed:
switch strings.TrimSuffix(string(body), "\n") {
case errIncompatibleVersion.Error():
plog.Errorf("request sent was ignored by peer %s (server version incompatible)", to)
return errIncompatibleVersion
case errClusterIDMismatch.Error():
plog.Errorf("request sent was ignored (cluster ID mismatch: remote[%s]=%s, local=%s)",
to, resp.Header.Get("X-Etcd-Cluster-ID"), req.Header.Get("X-Etcd-Cluster-ID"))
return errClusterIDMismatch
default:
return fmt.Errorf("unhandled error %q when precondition failed", string(body))
}
case http.StatusForbidden:
return errMemberRemoved
case http.StatusNoContent:
return nil
default:
return fmt.Errorf("unexpected http status %s while posting to %q", http.StatusText(resp.StatusCode), req.URL.String())
}
}
// reportErr reports the given error through sending it into
// the given error channel.
// If the error channel is filled up when sending error, it drops the error
// because the fact that error has happened is reported, which is
// good enough.
func reportCriticalError(err error, errc chan<- error) {
select {
case errc <- err:
default:
}
}
// compareMajorMinorVersion returns an integer comparing two versions based on
// their major and minor version. The result will be 0 if a==b, -1 if a < b,
// and 1 if a > b.
func compareMajorMinorVersion(a, b *semver.Version) int {
na := &semver.Version{Major: a.Major, Minor: a.Minor}
nb := &semver.Version{Major: b.Major, Minor: b.Minor}
switch {
case na.LessThan(*nb):
return -1
case nb.LessThan(*na):
return 1
default:
return 0
}
}
// serverVersion returns the server version from the given header.
func serverVersion(h http.Header) *semver.Version {
verStr := h.Get("X-Server-Version")
// backward compatibility with etcd 2.0
if verStr == "" {
verStr = "2.0.0"
}
return semver.Must(semver.NewVersion(verStr))
}
// serverVersion returns the min cluster version from the given header.
func minClusterVersion(h http.Header) *semver.Version {
verStr := h.Get("X-Min-Cluster-Version")
// backward compatibility with etcd 2.0
if verStr == "" {
verStr = "2.0.0"
}
return semver.Must(semver.NewVersion(verStr))
}
// checkVersionCompability checks whether the given version is compatible
// with the local version.
func checkVersionCompability(name string, server, minCluster *semver.Version) error {
localServer := semver.Must(semver.NewVersion(version.Version))
localMinCluster := semver.Must(semver.NewVersion(version.MinClusterVersion))
if compareMajorMinorVersion(server, localMinCluster) == -1 {
return fmt.Errorf("remote version is too low: remote[%s]=%s, local=%s", name, server, localServer)
}
if compareMajorMinorVersion(minCluster, localServer) == 1 {
return fmt.Errorf("local version is too low: remote[%s]=%s, local=%s", name, server, localServer)
}
return nil
}