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package checksum
import (
"context"
"fmt"
"strings"
"github.com/aws/smithy-go"
"github.com/aws/smithy-go/logging"
"github.com/aws/smithy-go/middleware"
smithyhttp "github.com/aws/smithy-go/transport/http"
)
// outputValidationAlgorithmsUsedKey is the metadata key for indexing the algorithms
// that were used, by the middleware's validation.
type outputValidationAlgorithmsUsedKey struct{}
// GetOutputValidationAlgorithmsUsed returns the checksum algorithms used
// stored in the middleware Metadata. Returns false if no algorithms were
// stored in the Metadata.
func GetOutputValidationAlgorithmsUsed(m middleware.Metadata) ([]string, bool) {
vs, ok := m.Get(outputValidationAlgorithmsUsedKey{}).([]string)
return vs, ok
}
// SetOutputValidationAlgorithmsUsed stores the checksum algorithms used in the
// middleware Metadata.
func SetOutputValidationAlgorithmsUsed(m *middleware.Metadata, vs []string) {
m.Set(outputValidationAlgorithmsUsedKey{}, vs)
}
// validateOutputPayloadChecksum middleware computes payload checksum of the
// received response and validates with checksum returned by the service.
type validateOutputPayloadChecksum struct {
// Algorithms represents a priority-ordered list of valid checksum
// algorithm that should be validated when present in HTTP response
// headers.
Algorithms []Algorithm
// IgnoreMultipartValidation indicates multipart checksums ending with "-#"
// will be ignored.
IgnoreMultipartValidation bool
// When set the middleware will log when output does not have checksum or
// algorithm to validate.
LogValidationSkipped bool
// When set the middleware will log when the output contains a multipart
// checksum that was, skipped and not validated.
LogMultipartValidationSkipped bool
}
func (m *validateOutputPayloadChecksum) ID() string {
return "AWSChecksum:ValidateOutputPayloadChecksum"
}
// HandleDeserialize is a Deserialize middleware that wraps the HTTP response
// body with an io.ReadCloser that will validate the its checksum.
func (m *validateOutputPayloadChecksum) HandleDeserialize(
ctx context.Context, in middleware.DeserializeInput, next middleware.DeserializeHandler,
) (
out middleware.DeserializeOutput, metadata middleware.Metadata, err error,
) {
out, metadata, err = next.HandleDeserialize(ctx, in)
if err != nil {
return out, metadata, err
}
// If there is no validation mode specified nothing is supported.
if mode := getContextOutputValidationMode(ctx); mode != "ENABLED" {
return out, metadata, err
}
response, ok := out.RawResponse.(*smithyhttp.Response)
if !ok {
return out, metadata, &smithy.DeserializationError{
Err: fmt.Errorf("unknown transport type %T", out.RawResponse),
}
}
var expectedChecksum string
var algorithmToUse Algorithm
for _, algorithm := range m.Algorithms {
value := response.Header.Get(AlgorithmHTTPHeader(algorithm))
if len(value) == 0 {
continue
}
expectedChecksum = value
algorithmToUse = algorithm
}
// TODO this must validate the validation mode is set to enabled.
logger := middleware.GetLogger(ctx)
// Skip validation if no checksum algorithm or checksum is available.
if len(expectedChecksum) == 0 || len(algorithmToUse) == 0 {
if m.LogValidationSkipped {
// TODO this probably should have more information about the
// operation output that won't be validated.
logger.Logf(logging.Warn,
"Response has no supported checksum. Not validating response payload.")
}
return out, metadata, nil
}
// Ignore multipart validation
if m.IgnoreMultipartValidation && strings.Contains(expectedChecksum, "-") {
if m.LogMultipartValidationSkipped {
// TODO this probably should have more information about the
// operation output that won't be validated.
logger.Logf(logging.Warn, "Skipped validation of multipart checksum.")
}
return out, metadata, nil
}
body, err := newValidateChecksumReader(response.Body, algorithmToUse, expectedChecksum)
if err != nil {
return out, metadata, fmt.Errorf("failed to create checksum validation reader, %w", err)
}
response.Body = body
// Update the metadata to include the set of the checksum algorithms that
// will be validated.
SetOutputValidationAlgorithmsUsed(&metadata, []string{
string(algorithmToUse),
})
return out, metadata, nil
}
|
