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aws/request: Fix HTTP Request Body race condition. #874

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Oct 6, 2016
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4 changes: 1 addition & 3 deletions aws/client/client.go
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ package client

import (
"fmt"
"io/ioutil"
"net/http/httputil"

"github.com/aws/aws-sdk-go/aws"
Expand Down Expand Up @@ -104,8 +103,7 @@ func logRequest(r *request.Request) {
// Reset the request body because dumpRequest will re-wrap the r.HTTPRequest's
// Body as a NoOpCloser and will not be reset after read by the HTTP
// client reader.
r.Body.Seek(r.BodyStart, 0)
r.HTTPRequest.Body = ioutil.NopCloser(r.Body)
r.ResetBody()
}

r.Config.Logger.Log(fmt.Sprintf(logReqMsg, r.ClientInfo.ServiceName, r.Operation.Name, string(dumpedBody)))
Expand Down
19 changes: 14 additions & 5 deletions aws/request/offset_reader.go
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ import (
// with retrying requests
type offsetReader struct {
buf io.ReadSeeker
lock sync.RWMutex
lock sync.Mutex
closed bool
}

Expand All @@ -21,18 +21,19 @@ func newOffsetReader(buf io.ReadSeeker, offset int64) *offsetReader {
return reader
}

// Close is a thread-safe close. Uses the write lock.
// Close will close the instance of the offset reader's access to
// the underlying io.ReadSeeker.
func (o *offsetReader) Close() error {
o.lock.Lock()
defer o.lock.Unlock()
o.closed = true
return nil
}

// Read is a thread-safe read using a read lock.
// Read is a thread-safe read of the underlying io.ReadSeeker
func (o *offsetReader) Read(p []byte) (int, error) {
o.lock.RLock()
defer o.lock.RUnlock()
o.lock.Lock()
defer o.lock.Unlock()

if o.closed {
return 0, io.EOF
Expand All @@ -41,6 +42,14 @@ func (o *offsetReader) Read(p []byte) (int, error) {
return o.buf.Read(p)
}

// Seek is a thread-safe seeking operation.
func (o *offsetReader) Seek(offset int64, whence int) (int64, error) {
o.lock.Lock()
defer o.lock.Unlock()

return o.buf.Seek(offset, whence)
}

// CloseAndCopy will return a new offsetReader with a copy of the old buffer
// and close the old buffer.
func (o *offsetReader) CloseAndCopy(offset int64) *offsetReader {
Expand Down
17 changes: 17 additions & 0 deletions aws/request/offset_reader_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,23 @@ func TestOffsetReaderRead(t *testing.T) {
assert.Equal(t, buf, tempBuf)
}

func TestOffsetReaderSeek(t *testing.T) {
buf := []byte("testData")
reader := newOffsetReader(bytes.NewReader(buf), 0)

orig, err := reader.Seek(0, 1)
assert.NoError(t, err)
assert.Equal(t, int64(0), orig)

n, err := reader.Seek(0, 2)
assert.NoError(t, err)
assert.Equal(t, int64(len(buf)), n)

n, err = reader.Seek(orig, 0)
assert.NoError(t, err)
assert.Equal(t, int64(0), n)
}

func TestOffsetReaderClose(t *testing.T) {
buf := []byte("testData")
reader := &offsetReader{buf: bytes.NewReader(buf)}
Expand Down
50 changes: 34 additions & 16 deletions aws/request/request.go
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@ import (
"bytes"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"reflect"
Expand Down Expand Up @@ -42,6 +41,12 @@ type Request struct {
LastSignedAt time.Time

built bool

// Need to persist an intermideant body betweend the input Body and HTTP
// request body because the HTTP Client's transport can maintain a reference
// to the HTTP request's body after the client has returned. This value is
// safe to use concurrently and rewraps the input Body for each HTTP request.
safeBody *offsetReader
}

// An Operation is the service API operation to be made.
Expand Down Expand Up @@ -135,8 +140,8 @@ func (r *Request) SetStringBody(s string) {

// SetReaderBody will set the request's body reader.
func (r *Request) SetReaderBody(reader io.ReadSeeker) {
r.HTTPRequest.Body = newOffsetReader(reader, 0)
r.Body = reader
r.ResetBody()
}

// Presign returns the request's signed URL. Error will be returned
Expand Down Expand Up @@ -220,6 +225,24 @@ func (r *Request) Sign() error {
return r.Error
}

// ResetBody rewinds the request body backto its starting position, and
// set's the HTTP Request body reference. When the body is read prior
// to being sent in the HTTP request it will need to be rewound.
func (r *Request) ResetBody() {
if r.safeBody != nil {
r.safeBody.Close()
}

r.safeBody = newOffsetReader(r.Body, r.BodyStart)
r.HTTPRequest.Body = r.safeBody
}

// GetBody will return an io.ReadSeeker of the Request's underlying
// input body with a concurrency safe wrapper.
func (r *Request) GetBody() io.ReadSeeker {
return r.safeBody
}

// Send will send the request returning error if errors are encountered.
//
// Send will sign the request prior to sending. All Send Handlers will
Expand All @@ -231,6 +254,8 @@ func (r *Request) Sign() error {
//
// readLoop() and getConn(req *Request, cm connectMethod)
// https://github.com/golang/go/blob/master/src/net/http/transport.go
//
// Send will not close the request.Request's body.
func (r *Request) Send() error {
for {
if aws.BoolValue(r.Retryable) {
Expand All @@ -239,21 +264,15 @@ func (r *Request) Send() error {
r.ClientInfo.ServiceName, r.Operation.Name, r.RetryCount))
}

var body io.ReadCloser
if reader, ok := r.HTTPRequest.Body.(*offsetReader); ok {
body = reader.CloseAndCopy(r.BodyStart)
} else {
if r.Config.Logger != nil {
r.Config.Logger.Log("Request body type has been overwritten. May cause race conditions")
}
r.Body.Seek(r.BodyStart, 0)
body = ioutil.NopCloser(r.Body)
}
// The previous http.Request will have a reference to the r.Body
// and the HTTP Client's Transport may still be reading from
// the request's body even though the Client's Do returned.
r.HTTPRequest = copyHTTPRequest(r.HTTPRequest, nil)
r.ResetBody()

r.HTTPRequest = copyHTTPRequest(r.HTTPRequest, body)
// Closing response body to ensure that no response body is leaked
// between retry attempts.
if r.HTTPResponse != nil && r.HTTPResponse.Body != nil {
// Closing response body. Since we are setting a new request to send off, this
// response will get squashed and leaked.
r.HTTPResponse.Body.Close()
}
}
Expand Down Expand Up @@ -281,7 +300,6 @@ func (r *Request) Send() error {
debugLogReqError(r, "Send Request", true, err)
continue
}

r.Handlers.UnmarshalMeta.Run(r)
r.Handlers.ValidateResponse.Run(r)
if r.Error != nil {
Expand Down
4 changes: 3 additions & 1 deletion aws/signer/v4/v4.go
Original file line number Diff line number Diff line change
Expand Up @@ -366,7 +366,9 @@ func signSDKRequestWithCurrTime(req *request.Request, curTimeFn func() time.Time
signingTime = req.LastSignedAt
}

signedHeaders, err := v4.signWithBody(req.HTTPRequest, req.Body, name, region, req.ExpireTime, signingTime)
signedHeaders, err := v4.signWithBody(req.HTTPRequest, req.GetBody(),
name, region, req.ExpireTime, signingTime,
)
if err != nil {
req.Error = err
req.SignedHeaderVals = nil
Expand Down