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api.go
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/*
* Minio Go Library for Amazon S3 Compatible Cloud Storage (C) 2015, 2016 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 minio
import (
"bytes"
"encoding/base64"
"encoding/hex"
"fmt"
"io"
"io/ioutil"
"math/rand"
"net/http"
"net/http/httputil"
"net/url"
"os"
"regexp"
"runtime"
"strings"
"sync"
"time"
"github.com/minio/minio-go/pkg/s3signer"
"github.com/minio/minio-go/pkg/s3utils"
)
// Client implements Amazon S3 compatible methods.
type Client struct {
/// Standard options.
// Parsed endpoint url provided by the user.
endpointURL url.URL
// AccessKeyID required for authorized requests.
accessKeyID string
// SecretAccessKey required for authorized requests.
secretAccessKey string
// Choose a signature type if necessary.
signature SignatureType
// Set to 'true' if Client has no access and secret keys.
anonymous bool
// User supplied.
appInfo struct {
appName string
appVersion string
}
// Indicate whether we are using https or not
secure bool
// Needs allocation.
httpClient *http.Client
bucketLocCache *bucketLocationCache
// Advanced functionality.
isTraceEnabled bool
traceOutput io.Writer
// S3 specific accelerated endpoint.
s3AccelerateEndpoint string
// Random seed.
random *rand.Rand
}
// Global constants.
const (
libraryName = "minio-go"
libraryVersion = "2.0.4"
)
// User Agent should always following the below style.
// Please open an issue to discuss any new changes here.
//
// Minio (OS; ARCH) LIB/VER APP/VER
const (
libraryUserAgentPrefix = "Minio (" + runtime.GOOS + "; " + runtime.GOARCH + ") "
libraryUserAgent = libraryUserAgentPrefix + libraryName + "/" + libraryVersion
)
// NewV2 - instantiate minio client with Amazon S3 signature version
// '2' compatibility.
func NewV2(endpoint string, accessKeyID, secretAccessKey string, secure bool) (*Client, error) {
clnt, err := privateNew(endpoint, accessKeyID, secretAccessKey, secure)
if err != nil {
return nil, err
}
// Set to use signature version '2'.
clnt.signature = SignatureV2
return clnt, nil
}
// NewV4 - instantiate minio client with Amazon S3 signature version
// '4' compatibility.
func NewV4(endpoint string, accessKeyID, secretAccessKey string, secure bool) (*Client, error) {
clnt, err := privateNew(endpoint, accessKeyID, secretAccessKey, secure)
if err != nil {
return nil, err
}
// Set to use signature version '4'.
clnt.signature = SignatureV4
return clnt, nil
}
// New - instantiate minio client Client, adds automatic verification
// of signature.
func New(endpoint string, accessKeyID, secretAccessKey string, secure bool) (*Client, error) {
clnt, err := privateNew(endpoint, accessKeyID, secretAccessKey, secure)
if err != nil {
return nil, err
}
// Google cloud storage should be set to signature V2, force it if not.
if s3utils.IsGoogleEndpoint(clnt.endpointURL) {
clnt.signature = SignatureV2
}
// If Amazon S3 set to signature v2.n
if s3utils.IsAmazonEndpoint(clnt.endpointURL) {
clnt.signature = SignatureV4
}
return clnt, nil
}
// lockedRandSource provides protected rand source, implements rand.Source interface.
type lockedRandSource struct {
lk sync.Mutex
src rand.Source
}
// Int63 returns a non-negative pseudo-random 63-bit integer as an
// int64.
func (r *lockedRandSource) Int63() (n int64) {
r.lk.Lock()
n = r.src.Int63()
r.lk.Unlock()
return
}
// Seed uses the provided seed value to initialize the generator to a
// deterministic state.
func (r *lockedRandSource) Seed(seed int64) {
r.lk.Lock()
r.src.Seed(seed)
r.lk.Unlock()
}
// redirectHeaders copies all headers when following a redirect URL.
// This won't be needed anymore from go 1.8 (https://github.com/golang/go/issues/4800)
func redirectHeaders(req *http.Request, via []*http.Request) error {
if len(via) == 0 {
return nil
}
for key, val := range via[0].Header {
req.Header[key] = val
}
return nil
}
func privateNew(endpoint, accessKeyID, secretAccessKey string, secure bool) (*Client, error) {
// construct endpoint.
endpointURL, err := getEndpointURL(endpoint, secure)
if err != nil {
return nil, err
}
// instantiate new Client.
clnt := new(Client)
clnt.accessKeyID = accessKeyID
clnt.secretAccessKey = secretAccessKey
if clnt.accessKeyID == "" || clnt.secretAccessKey == "" {
clnt.anonymous = true
}
// Remember whether we are using https or not
clnt.secure = secure
// Save endpoint URL, user agent for future uses.
clnt.endpointURL = *endpointURL
// Instantiate http client and bucket location cache.
clnt.httpClient = &http.Client{
Transport: http.DefaultTransport,
CheckRedirect: redirectHeaders,
}
// Instantiae bucket location cache.
clnt.bucketLocCache = newBucketLocationCache()
// Introduce a new locked random seed.
clnt.random = rand.New(&lockedRandSource{src: rand.NewSource(time.Now().UTC().UnixNano())})
// Return.
return clnt, nil
}
// SetAppInfo - add application details to user agent.
func (c *Client) SetAppInfo(appName string, appVersion string) {
// if app name and version not set, we do not set a new user agent.
if appName != "" && appVersion != "" {
c.appInfo = struct {
appName string
appVersion string
}{}
c.appInfo.appName = appName
c.appInfo.appVersion = appVersion
}
}
// SetCustomTransport - set new custom transport.
func (c *Client) SetCustomTransport(customHTTPTransport http.RoundTripper) {
// Set this to override default transport
// ``http.DefaultTransport``.
//
// This transport is usually needed for debugging OR to add your
// own custom TLS certificates on the client transport, for custom
// CA's and certs which are not part of standard certificate
// authority follow this example :-
//
// tr := &http.Transport{
// TLSClientConfig: &tls.Config{RootCAs: pool},
// DisableCompression: true,
// }
// api.SetTransport(tr)
//
if c.httpClient != nil {
c.httpClient.Transport = customHTTPTransport
}
}
// TraceOn - enable HTTP tracing.
func (c *Client) TraceOn(outputStream io.Writer) {
// if outputStream is nil then default to os.Stdout.
if outputStream == nil {
outputStream = os.Stdout
}
// Sets a new output stream.
c.traceOutput = outputStream
// Enable tracing.
c.isTraceEnabled = true
}
// TraceOff - disable HTTP tracing.
func (c *Client) TraceOff() {
// Disable tracing.
c.isTraceEnabled = false
}
// SetS3TransferAccelerate - turns s3 accelerated endpoint on or off for all your
// requests. This feature is only specific to S3 for all other endpoints this
// function does nothing. To read further details on s3 transfer acceleration
// please vist -
// http://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html
func (c *Client) SetS3TransferAccelerate(accelerateEndpoint string) {
if s3utils.IsAmazonEndpoint(c.endpointURL) {
c.s3AccelerateEndpoint = accelerateEndpoint
}
}
// requestMetadata - is container for all the values to make a request.
type requestMetadata struct {
// If set newRequest presigns the URL.
presignURL bool
// User supplied.
bucketName string
objectName string
queryValues url.Values
customHeader http.Header
expires int64
// Generated by our internal code.
bucketLocation string
contentBody io.Reader
contentLength int64
contentSHA256Bytes []byte
contentMD5Bytes []byte
}
// regCred matches credential string in HTTP header
var regCred = regexp.MustCompile("Credential=([A-Z0-9]+)/")
// regCred matches signature string in HTTP header
var regSign = regexp.MustCompile("Signature=([[0-9a-f]+)")
// Filter out signature value from Authorization header.
func (c Client) filterSignature(req *http.Request) {
// For anonymous requests, no need to filter.
if c.anonymous {
return
}
// Handle if Signature V2.
if c.signature.isV2() {
// Set a temporary redacted auth
req.Header.Set("Authorization", "AWS **REDACTED**:**REDACTED**")
return
}
/// Signature V4 authorization header.
// Save the original auth.
origAuth := req.Header.Get("Authorization")
// Strip out accessKeyID from:
// Credential=<access-key-id>/<date>/<aws-region>/<aws-service>/aws4_request
newAuth := regCred.ReplaceAllString(origAuth, "Credential=**REDACTED**/")
// Strip out 256-bit signature from: Signature=<256-bit signature>
newAuth = regSign.ReplaceAllString(newAuth, "Signature=**REDACTED**")
// Set a temporary redacted auth
req.Header.Set("Authorization", newAuth)
return
}
// dumpHTTP - dump HTTP request and response.
func (c Client) dumpHTTP(req *http.Request, resp *http.Response) error {
// Starts http dump.
_, err := fmt.Fprintln(c.traceOutput, "---------START-HTTP---------")
if err != nil {
return err
}
// Filter out Signature field from Authorization header.
c.filterSignature(req)
// Only display request header.
reqTrace, err := httputil.DumpRequestOut(req, false)
if err != nil {
return err
}
// Write request to trace output.
_, err = fmt.Fprint(c.traceOutput, string(reqTrace))
if err != nil {
return err
}
// Only display response header.
var respTrace []byte
// For errors we make sure to dump response body as well.
if resp.StatusCode != http.StatusOK &&
resp.StatusCode != http.StatusPartialContent &&
resp.StatusCode != http.StatusNoContent {
respTrace, err = httputil.DumpResponse(resp, true)
if err != nil {
return err
}
} else {
// WORKAROUND for https://github.com/golang/go/issues/13942.
// httputil.DumpResponse does not print response headers for
// all successful calls which have response ContentLength set
// to zero. Keep this workaround until the above bug is fixed.
if resp.ContentLength == 0 {
var buffer bytes.Buffer
if err = resp.Header.Write(&buffer); err != nil {
return err
}
respTrace = buffer.Bytes()
respTrace = append(respTrace, []byte("\r\n")...)
} else {
respTrace, err = httputil.DumpResponse(resp, false)
if err != nil {
return err
}
}
}
// Write response to trace output.
_, err = fmt.Fprint(c.traceOutput, strings.TrimSuffix(string(respTrace), "\r\n"))
if err != nil {
return err
}
// Ends the http dump.
_, err = fmt.Fprintln(c.traceOutput, "---------END-HTTP---------")
if err != nil {
return err
}
// Returns success.
return nil
}
// do - execute http request.
func (c Client) do(req *http.Request) (*http.Response, error) {
var resp *http.Response
var err error
// Do the request in a loop in case of 307 http is met since golang still doesn't
// handle properly this situation (https://github.com/golang/go/issues/7912)
for {
resp, err = c.httpClient.Do(req)
if err != nil {
// Handle this specifically for now until future Golang
// versions fix this issue properly.
urlErr, ok := err.(*url.Error)
if ok && strings.Contains(urlErr.Err.Error(), "EOF") {
return nil, &url.Error{
Op: urlErr.Op,
URL: urlErr.URL,
Err: fmt.Errorf("Connection closed by foreign host %s. Retry again.", urlErr.URL),
}
}
return nil, err
}
// Redo the request with the new redirect url if http 307 is returned, quit the loop otherwise
if resp != nil && resp.StatusCode == http.StatusTemporaryRedirect {
newURL, err := url.Parse(resp.Header.Get("Location"))
if err != nil {
break
}
req.URL = newURL
} else {
break
}
}
// Response cannot be non-nil, report if its the case.
if resp == nil {
msg := "Response is empty. " + reportIssue
return nil, ErrInvalidArgument(msg)
}
// If trace is enabled, dump http request and response.
if c.isTraceEnabled {
err = c.dumpHTTP(req, resp)
if err != nil {
return nil, err
}
}
return resp, nil
}
// List of success status.
var successStatus = []int{
http.StatusOK,
http.StatusNoContent,
http.StatusPartialContent,
}
// executeMethod - instantiates a given method, and retries the
// request upon any error up to maxRetries attempts in a binomially
// delayed manner using a standard back off algorithm.
func (c Client) executeMethod(method string, metadata requestMetadata) (res *http.Response, err error) {
var isRetryable bool // Indicates if request can be retried.
var bodySeeker io.Seeker // Extracted seeker from io.Reader.
if metadata.contentBody != nil {
// Check if body is seekable then it is retryable.
bodySeeker, isRetryable = metadata.contentBody.(io.Seeker)
}
// Create a done channel to control 'ListObjects' go routine.
doneCh := make(chan struct{}, 1)
// Indicate to our routine to exit cleanly upon return.
defer close(doneCh)
// Blank indentifier is kept here on purpose since 'range' without
// blank identifiers is only supported since go1.4
// https://golang.org/doc/go1.4#forrange.
for _ = range c.newRetryTimer(MaxRetry, time.Second, time.Second*30, MaxJitter, doneCh) {
// Retry executes the following function body if request has an
// error until maxRetries have been exhausted, retry attempts are
// performed after waiting for a given period of time in a
// binomial fashion.
if isRetryable {
// Seek back to beginning for each attempt.
if _, err = bodySeeker.Seek(0, 0); err != nil {
// If seek failed, no need to retry.
return nil, err
}
}
// Instantiate a new request.
var req *http.Request
req, err = c.newRequest(method, metadata)
if err != nil {
errResponse := ToErrorResponse(err)
if isS3CodeRetryable(errResponse.Code) {
continue // Retry.
}
return nil, err
}
// Initiate the request.
res, err = c.do(req)
if err != nil {
// For supported network errors verify.
if isNetErrorRetryable(err) {
continue // Retry.
}
// For other errors, return here no need to retry.
return nil, err
}
// For any known successful http status, return quickly.
for _, httpStatus := range successStatus {
if httpStatus == res.StatusCode {
return res, nil
}
}
// Read the body to be saved later.
errBodyBytes, err := ioutil.ReadAll(res.Body)
// res.Body should be closed
closeResponse(res)
if err != nil {
return nil, err
}
// Save the body.
errBodySeeker := bytes.NewReader(errBodyBytes)
res.Body = ioutil.NopCloser(errBodySeeker)
// For errors verify if its retryable otherwise fail quickly.
errResponse := ToErrorResponse(httpRespToErrorResponse(res, metadata.bucketName, metadata.objectName))
// Bucket region if set in error response, we can retry the
// request with the new region.
if errResponse.Region != "" {
c.bucketLocCache.Set(metadata.bucketName, errResponse.Region)
continue // Retry.
}
// Verify if error response code is retryable.
if isS3CodeRetryable(errResponse.Code) {
continue // Retry.
}
// Verify if http status code is retryable.
if isHTTPStatusRetryable(res.StatusCode) {
continue // Retry.
}
// Save the body back again.
errBodySeeker.Seek(0, 0) // Seek back to starting point.
res.Body = ioutil.NopCloser(errBodySeeker)
// For all other cases break out of the retry loop.
break
}
return res, err
}
// newRequest - instantiate a new HTTP request for a given method.
func (c Client) newRequest(method string, metadata requestMetadata) (req *http.Request, err error) {
// If no method is supplied default to 'POST'.
if method == "" {
method = "POST"
}
// Default all requests to "us-east-1" or "cn-north-1" (china region)
location := "us-east-1"
if s3utils.IsAmazonChinaEndpoint(c.endpointURL) {
// For china specifically we need to set everything to
// cn-north-1 for now, there is no easier way until AWS S3
// provides a cleaner compatible API across "us-east-1" and
// China region.
location = "cn-north-1"
}
// Gather location only if bucketName is present.
if metadata.bucketName != "" {
location, err = c.getBucketLocation(metadata.bucketName)
if err != nil {
return nil, err
}
}
// Save location.
metadata.bucketLocation = location
// Construct a new target URL.
targetURL, err := c.makeTargetURL(metadata.bucketName, metadata.objectName, metadata.bucketLocation, metadata.queryValues)
if err != nil {
return nil, err
}
// Initialize a new HTTP request for the method.
req, err = http.NewRequest(method, targetURL.String(), nil)
if err != nil {
return nil, err
}
// Generate presign url if needed, return right here.
if metadata.expires != 0 && metadata.presignURL {
if c.anonymous {
return nil, ErrInvalidArgument("Requests cannot be presigned with anonymous credentials.")
}
if c.signature.isV2() {
// Presign URL with signature v2.
req = s3signer.PreSignV2(*req, c.accessKeyID, c.secretAccessKey, metadata.expires)
} else {
// Presign URL with signature v4.
req = s3signer.PreSignV4(*req, c.accessKeyID, c.secretAccessKey, location, metadata.expires)
}
return req, nil
}
// Set content body if available.
if metadata.contentBody != nil {
req.Body = ioutil.NopCloser(metadata.contentBody)
}
// FIXME: Enable this when Google Cloud Storage properly supports 100-continue.
// Skip setting 'expect' header for Google Cloud Storage, there
// are some known issues - https://github.com/restic/restic/issues/520
if !s3utils.IsGoogleEndpoint(c.endpointURL) && c.s3AccelerateEndpoint == "" {
// Set 'Expect' header for the request.
req.Header.Set("Expect", "100-continue")
}
// Set 'User-Agent' header for the request.
c.setUserAgent(req)
// Set all headers.
for k, v := range metadata.customHeader {
req.Header.Set(k, v[0])
}
// set incoming content-length.
if metadata.contentLength > 0 {
req.ContentLength = metadata.contentLength
}
// Set sha256 sum only for non anonymous credentials.
if !c.anonymous {
// set sha256 sum for signature calculation only with
// signature version '4'.
if c.signature.isV4() {
shaHeader := unsignedPayload
if !c.secure {
if metadata.contentSHA256Bytes == nil {
shaHeader = hex.EncodeToString(sum256([]byte{}))
} else {
shaHeader = hex.EncodeToString(metadata.contentSHA256Bytes)
}
}
req.Header.Set("X-Amz-Content-Sha256", shaHeader)
}
}
// set md5Sum for content protection.
if metadata.contentMD5Bytes != nil {
req.Header.Set("Content-Md5", base64.StdEncoding.EncodeToString(metadata.contentMD5Bytes))
}
// Sign the request for all authenticated requests.
if !c.anonymous {
if c.signature.isV2() {
// Add signature version '2' authorization header.
req = s3signer.SignV2(*req, c.accessKeyID, c.secretAccessKey)
} else if c.signature.isV4() {
// Add signature version '4' authorization header.
req = s3signer.SignV4(*req, c.accessKeyID, c.secretAccessKey, location)
}
}
// Return request.
return req, nil
}
// set User agent.
func (c Client) setUserAgent(req *http.Request) {
req.Header.Set("User-Agent", libraryUserAgent)
if c.appInfo.appName != "" && c.appInfo.appVersion != "" {
req.Header.Set("User-Agent", libraryUserAgent+" "+c.appInfo.appName+"/"+c.appInfo.appVersion)
}
}
// makeTargetURL make a new target url.
func (c Client) makeTargetURL(bucketName, objectName, bucketLocation string, queryValues url.Values) (*url.URL, error) {
host := c.endpointURL.Host
// For Amazon S3 endpoint, try to fetch location based endpoint.
if s3utils.IsAmazonEndpoint(c.endpointURL) {
if c.s3AccelerateEndpoint != "" && bucketName != "" {
// http://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html
// Disable transfer acceleration for non-compliant bucket names.
if strings.Contains(bucketName, ".") {
return nil, ErrTransferAccelerationBucket(bucketName)
}
// If transfer acceleration is requested set new host.
// For more details about enabling transfer acceleration read here.
// http://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html
host = c.s3AccelerateEndpoint
} else {
// Fetch new host based on the bucket location.
host = getS3Endpoint(bucketLocation)
}
}
// Save scheme.
scheme := c.endpointURL.Scheme
urlStr := scheme + "://" + host + "/"
// Make URL only if bucketName is available, otherwise use the
// endpoint URL.
if bucketName != "" {
// Save if target url will have buckets which suppport virtual host.
isVirtualHostStyle := s3utils.IsVirtualHostSupported(c.endpointURL, bucketName)
// If endpoint supports virtual host style use that always.
// Currently only S3 and Google Cloud Storage would support
// virtual host style.
if isVirtualHostStyle {
urlStr = scheme + "://" + bucketName + "." + host + "/"
if objectName != "" {
urlStr = urlStr + s3utils.EncodePath(objectName)
}
} else {
// If not fall back to using path style.
urlStr = urlStr + bucketName + "/"
if objectName != "" {
urlStr = urlStr + s3utils.EncodePath(objectName)
}
}
}
// If there are any query values, add them to the end.
if len(queryValues) > 0 {
urlStr = urlStr + "?" + s3utils.QueryEncode(queryValues)
}
u, err := url.Parse(urlStr)
if err != nil {
return nil, err
}
return u, nil
}