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Copy pathclient.go
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/*
* MinIO Cloud Storage, (C) 2018-2020 MinIO, 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 rest
import (
"context"
"errors"
"io"
"io/ioutil"
"math/rand"
"net/http"
"net/url"
"sync/atomic"
"time"
xhttp "github.com/minio/minio/cmd/http"
"github.com/minio/minio/cmd/logger"
xnet "github.com/minio/minio/pkg/net"
)
// DefaultTimeout - default REST timeout is 10 seconds.
const DefaultTimeout = 10 * time.Second
const (
offline = iota
online
closed
)
// NetworkError - error type in case of errors related to http/transport
// for ex. connection refused, connection reset, dns resolution failure etc.
// All errors returned by storage-rest-server (ex errFileNotFound, errDiskNotFound) are not considered to be network errors.
type NetworkError struct {
Err error
}
func (n *NetworkError) Error() string {
return n.Err.Error()
}
// Unwrap returns the error wrapped in NetworkError.
func (n *NetworkError) Unwrap() error {
return n.Err
}
// Client - http based RPC client.
type Client struct {
// HealthCheckFn is the function set to test for health.
// If not set the client will not keep track of health.
// Calling this returns true or false if the target
// is online or offline.
HealthCheckFn func() bool
// HealthCheckInterval will be the duration between re-connection attempts
// when a call has failed with a network error.
HealthCheckInterval time.Duration
// HealthCheckTimeout determines timeout for each call.
HealthCheckTimeout time.Duration
// MaxErrResponseSize is the maximum expected response size.
// Should only be modified before any calls are made.
MaxErrResponseSize int64
// ExpectTimeouts indicates if context timeouts are expected.
// This will not mark the client offline in these cases.
ExpectTimeouts bool
httpClient *http.Client
url *url.URL
newAuthToken func(audience string) string
connected int32
}
// URL query separator constants
const (
querySep = "?"
)
type restError string
func (e restError) Error() string {
return string(e)
}
func (e restError) Timeout() bool {
return true
}
// Call - make a REST call with context.
func (c *Client) Call(ctx context.Context, method string, values url.Values, body io.Reader, length int64) (reply io.ReadCloser, err error) {
if !c.IsOnline() {
return nil, &NetworkError{Err: &url.Error{Op: method, URL: c.url.String(), Err: restError("remote server offline")}}
}
req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url.String()+method+querySep+values.Encode(), body)
if err != nil {
return nil, &NetworkError{err}
}
req.Header.Set("Authorization", "Bearer "+c.newAuthToken(req.URL.RawQuery))
req.Header.Set("X-Minio-Time", time.Now().UTC().Format(time.RFC3339))
if length > 0 {
req.ContentLength = length
}
resp, err := c.httpClient.Do(req)
if err != nil {
if c.HealthCheckFn != nil && xnet.IsNetworkOrHostDown(err, c.ExpectTimeouts) {
logger.Info("Marking %s temporary offline; caused by %v", c.url.String(), err)
c.MarkOffline()
}
return nil, &NetworkError{err}
}
final := resp.Trailer.Get("FinalStatus")
if final != "" && final != "Success" {
defer xhttp.DrainBody(resp.Body)
return nil, errors.New(final)
}
if resp.StatusCode != http.StatusOK {
// If server returns 412 pre-condition failed, it would
// mean that authentication succeeded, but another
// side-channel check has failed, we shall take
// the client offline in such situations.
// generally all implementations should simply return
// 403, but in situations where there is a dependency
// with the caller to take the client offline purpose
// fully it should make sure to respond with '412'
// instead, see cmd/storage-rest-server.go for ideas.
if c.HealthCheckFn != nil && resp.StatusCode == http.StatusPreconditionFailed {
logger.Info("Marking %s temporary offline; caused by PreconditionFailed.", c.url.String())
c.MarkOffline()
}
defer xhttp.DrainBody(resp.Body)
// Limit the ReadAll(), just in case, because of a bug, the server responds with large data.
b, err := ioutil.ReadAll(io.LimitReader(resp.Body, c.MaxErrResponseSize))
if err != nil {
if c.HealthCheckFn != nil && xnet.IsNetworkOrHostDown(err, c.ExpectTimeouts) {
logger.Info("Marking %s temporary offline; caused by %v", c.url.String(), err)
c.MarkOffline()
}
return nil, err
}
if len(b) > 0 {
return nil, errors.New(string(b))
}
return nil, errors.New(resp.Status)
}
return resp.Body, nil
}
// Close closes all idle connections of the underlying http client
func (c *Client) Close() {
atomic.StoreInt32(&c.connected, closed)
}
// NewClient - returns new REST client.
func NewClient(url *url.URL, tr http.RoundTripper, newAuthToken func(aud string) string) *Client {
// Transport is exactly same as Go default in https://golang.org/pkg/net/http/#RoundTripper
// except custom DialContext and TLSClientConfig.
return &Client{
httpClient: &http.Client{Transport: tr},
url: url,
newAuthToken: newAuthToken,
connected: online,
MaxErrResponseSize: 4096,
HealthCheckInterval: 200 * time.Millisecond,
HealthCheckTimeout: time.Second,
}
}
// IsOnline returns whether the client is likely to be online.
func (c *Client) IsOnline() bool {
4686
return atomic.LoadInt32(&c.connected) == online
}
// MarkOffline - will mark a client as being offline and spawns
// a goroutine that will attempt to reconnect if HealthCheckFn is set.
func (c *Client) MarkOffline() {
// Start goroutine that will attempt to reconnect.
// If server is already trying to reconnect this will have no effect.
if c.HealthCheckFn != nil && atomic.CompareAndSwapInt32(&c.connected, online, offline) {
r := rand.New(rand.NewSource(time.Now().UnixNano()))
go func() {
for {
if atomic.LoadInt32(&c.connected) == closed {
return
}
if c.HealthCheckFn() {
atomic.CompareAndSwapInt32(&c.connected, offline, online)
logger.Info("Client %s online", c.url.String())
return
}
time.Sleep(time.Duration(r.Float64() * float64(c.HealthCheckInterval)))
}
}()
}
}