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package corehandlers
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"net/url"
"regexp"
"strconv"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/request"
)
// Interface for matching types which also have a Len method.
type lener interface {
Len() int
}
// BuildContentLengthHandler builds the content length of a request based on the body,
// or will use the HTTPRequest.Header's "Content-Length" if defined. If unable
// to determine request body length and no "Content-Length" was specified it will panic.
//
// The Content-Length will only be added to the request if the length of the body
// is greater than 0. If the body is empty or the current `Content-Length`
// header is <= 0, the header will also be stripped.
var BuildContentLengthHandler = request.NamedHandler{Name: "core.BuildContentLengthHandler", Fn: func(r *request.Request) {
var length int64
if slength := r.HTTPRequest.Header.Get("Content-Length"); slength != "" {
length, _ = strconv.ParseInt(slength, 10, 64)
} else {
if r.Body != nil {
var err error
length, err = aws.SeekerLen(r.Body)
if err != nil {
r.Error = awserr.New(request.ErrCodeSerialization, "failed to get request body's length", err)
return
}
}
}
if length > 0 {
r.HTTPRequest.ContentLength = length
r.HTTPRequest.Header.Set("Content-Length", fmt.Sprintf("%d", length))
} else {
r.HTTPRequest.ContentLength = 0
r.HTTPRequest.Header.Del("Content-Length")
}
}}
var reStatusCode = regexp.MustCompile(`^(\d{3})`)
// ValidateReqSigHandler is a request handler to ensure that the request's
// signature doesn't expire before it is sent. This can happen when a request
// is built and signed significantly before it is sent. Or significant delays
// occur when retrying requests that would cause the signature to expire.
var ValidateReqSigHandler = request.NamedHandler{
Name: "core.ValidateReqSigHandler",
Fn: func(r *request.Request) {
// Unsigned requests are not signed
if r.Config.Credentials == credentials.AnonymousCredentials {
return
}
signedTime := r.Time
if !r.LastSignedAt.IsZero() {
signedTime = r.LastSignedAt
}
// 5 minutes to allow for some clock skew/delays in transmission.
// Would be improved with aws/aws-sdk-go#423
if signedTime.Add(5 * time.Minute).After(time.Now()) {
return
}
fmt.Println("request expired, resigning")
r.Sign()
},
}
// SendHandler is a request handler to send service request using HTTP client.
var SendHandler = request.NamedHandler{
Name: "core.SendHandler",
Fn: func(r *request.Request) {
sender := sendFollowRedirects
if r.DisableFollowRedirects {
sender = sendWithoutFollowRedirects
}
if request.NoBody == r.HTTPRequest.Body {
// Strip off the request body if the NoBody reader was used as a
// place holder for a request body. This prevents the SDK from
// making requests with a request body when it would be invalid
// to do so.
//
// Use a shallow copy of the http.Request to ensure the race condition
// of transport on Body will not trigger
reqOrig, reqCopy := r.HTTPRequest, *r.HTTPRequest
reqCopy.Body = nil
r.HTTPRequest = &reqCopy
defer func() {
r.HTTPRequest = reqOrig
}()
}
var err error
r.HTTPResponse, err = sender(r)
if err != nil {
handleSendError(r, err)
}
},
}
func sendFollowRedirects(r *request.Request) (*http.Response, error) {
return r.Config.HTTPClient.Do(r.HTTPRequest)
}
func sendWithoutFollowRedirects(r *request.Request) (*http.Response, error) {
transport := r.Config.HTTPClient.Transport
if transport == nil {
transport = http.DefaultTransport
}
return transport.RoundTrip(r.HTTPRequest)
}
func handleSendError(r *request.Request, err error) {
// Prevent leaking if an HTTPResponse was returned. Clean up
// the body.
if r.HTTPResponse != nil {
r.HTTPResponse.Body.Close()
}
// Capture the case where url.Error is returned for error processing
// response. e.g. 301 without location header comes back as string
// error and r.HTTPResponse is nil. Other URL redirect errors will
// comeback in a similar method.
if e, ok := err.(*url.Error); ok && e.Err != nil {
if s := reStatusCode.FindStringSubmatch(e.Err.Error()); s != nil {
code, _ := strconv.ParseInt(s[1], 10, 64)
r.HTTPResponse = &http.Response{
StatusCode: int(code),
Status: http.StatusText(int(code)),
Body: ioutil.NopCloser(bytes.NewReader([]byte{})),
}
return
}
}
if r.HTTPResponse == nil {
// Add a dummy request response object to ensure the HTTPResponse
// value is consistent.
r.HTTPResponse = &http.Response{
StatusCode: int(0),
Status: http.StatusText(int(0)),
Body: ioutil.NopCloser(bytes.NewReader([]byte{})),
}
}
// Catch all other request errors.
r.Error = awserr.New("RequestError", "send request failed", err)
r.Retryable = aws.Bool(true) // network errors are retryable
// Override the error with a context canceled error, if that was canceled.
ctx := r.Context()
select {
case <-ctx.Done():
r.Error = awserr.New(request.CanceledErrorCode,
"request context canceled", ctx.Err())
r.Retryable = aws.Bool(false)
default:
}
}
// ValidateResponseHandler is a request handler to validate service response.
var ValidateResponseHandler = request.NamedHandler{Name: "core.ValidateResponseHandler", Fn: func(r *request.Request) {
if r.HTTPResponse.StatusCode == 0 || r.HTTPResponse.StatusCode >= 300 {
// this may be replaced by an UnmarshalError handler
r.Error = awserr.New("UnknownError", "unknown error", nil)
}
}}
// AfterRetryHandler performs final checks to determine if the request should
// be retried and how long to delay.
var AfterRetryHandler = request.NamedHandler{Name: "core.AfterRetryHandler", Fn: func(r *request.Request) {
// If one of the other handlers already set the retry state
// we don't want to override it based on the service's state
if r.Retryable == nil || aws.BoolValue(r.Config.EnforceShouldRetryCheck) {
r.Retryable = aws.Bool(r.ShouldRetry(r))
}
if r.WillRetry() {
r.RetryDelay = r.RetryRules(r)
if sleepFn := r.Config.SleepDelay; sleepFn != nil {
// Support SleepDelay for backwards compatibility and testing
sleepFn(r.RetryDelay)
} else if err := aws.SleepWithContext(r.Context(), r.RetryDelay); err != nil {
r.Error = awserr.New(request.CanceledErrorCode,
"request context canceled", err)
r.Retryable = aws.Bool(false)
return
}
// when the expired token exception occurs the credentials
// need to be expired locally so that the next request to
// get credentials will trigger a credentials refresh.
if r.IsErrorExpired() {
r.Config.Credentials.Expire()
}
r.RetryCount++
r.Error = nil
}
}}
// ValidateEndpointHandler is a request handler to validate a request had the
// appropriate Region and Endpoint set. Will set r.Error if the endpoint or
// region is not valid.
var ValidateEndpointHandler = request.NamedHandler{Name: "core.ValidateEndpointHandler", Fn: func(r *request.Request) {
if r.ClientInfo.SigningRegion == "" && aws.StringValue(r.Config.Region) == "" {
r.Error = aws.ErrMissingRegion
} else if r.ClientInfo.Endpoint == "" {
r.Error = aws.ErrMissingEndpoint
}
}}
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