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package sqs
import (
"crypto/md5"
"encoding/hex"
"fmt"
"strings"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/request"
)
var (
errChecksumMissingBody = fmt.Errorf("cannot compute checksum. missing body")
errChecksumMissingMD5 = fmt.Errorf("cannot verify checksum. missing response MD5")
)
func setupChecksumValidation(r *request.Request) {
if aws.BoolValue(r.Config.DisableComputeChecksums) {
return
}
switch r.Operation.Name {
case opSendMessage:
r.Handlers.Unmarshal.PushBack(verifySendMessage)
case opSendMessageBatch:
r.Handlers.Unmarshal.PushBack(verifySendMessageBatch)
case opReceiveMessage:
r.Handlers.Unmarshal.PushBack(verifyReceiveMessage)
}
}
func verifySendMessage(r *request.Request) {
if r.DataFilled() && r.ParamsFilled() {
in := r.Params.(*SendMessageInput)
out := r.Data.(*SendMessageOutput)
err := checksumsMatch(in.MessageBody, out.MD5OfMessageBody)
if err != nil {
setChecksumError(r, err.Error())
}
}
}
func verifySendMessageBatch(r *request.Request) {
if r.DataFilled() && r.ParamsFilled() {
entries := map[string]*SendMessageBatchResultEntry{}
ids := []string{}
out := r.Data.(*SendMessageBatchOutput)
for _, entry := range out.Successful {
entries[*entry.Id] = entry
}
in := r.Params.(*SendMessageBatchInput)
for _, entry := range in.Entries {
if e := entries[*entry.Id]; e != nil {
err := checksumsMatch(entry.MessageBody, e.MD5OfMessageBody)
if err != nil {
ids = append(ids, *e.MessageId)
}
}
}
if len(ids) > 0 {
setChecksumError(r, "invalid messages: %s", strings.Join(ids, ", "))
}
}
}
func verifyReceiveMessage(r *request.Request) {
if r.DataFilled() && r.ParamsFilled() {
ids := []string{}
out := r.Data.(*ReceiveMessageOutput)
for _, msg := range out.Messages {
err := checksumsMatch(msg.Body, msg.MD5OfBody)
if err != nil {
ids = append(ids, *msg.MessageId)
}
}
if len(ids) > 0 {
setChecksumError(r, "invalid messages: %s", strings.Join(ids, ", "))
}
}
}
func checksumsMatch(body, expectedMD5 *string) error {
if body == nil {
return errChecksumMissingBody
} else if expectedMD5 == nil {
return errChecksumMissingMD5
}
msum := md5.Sum([]byte(*body))
sum := hex.EncodeToString(msum[:])
if sum != *expectedMD5 {
return fmt.Errorf("expected MD5 checksum '%s', got '%s'", *expectedMD5, sum)
}
return nil
}
func setChecksumError(r *request.Request, format string, args ...interface{}) {
r.Retryable = aws.Bool(true)
r.Error = awserr.New("InvalidChecksum", fmt.Sprintf(format, args...), nil)
}
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