Method _modify_request_before_signing

awscli/botocore/auth.py:629–692

(self, request)

        self._expires = expires

    def _modify_request_before_signing(self, request):
        # We automatically set this header, so if it's the auto-set value we
        # want to get rid of it since it doesn't make sense for presigned urls.
        content_type = request.headers.get('content-type')
        blocklisted_content_type = (
            'application/x-www-form-urlencoded; charset=utf-8'
        )
        if content_type == blocklisted_content_type:
            del request.headers['content-type']

        # Note that we're not including X-Amz-Signature.
        # From the docs: "The Canonical Query String must include all the query
        # parameters from the preceding table except for X-Amz-Signature.
        signed_headers = self.signed_headers(self.headers_to_sign(request))

        auth_params = {
            'X-Amz-Algorithm': 'AWS4-HMAC-SHA256',
            'X-Amz-Credential': self.scope(request),
            'X-Amz-Date': request.context['timestamp'],
            'X-Amz-Expires': self._expires,
            'X-Amz-SignedHeaders': signed_headers,
        }
        if self.credentials.token is not None:
            auth_params['X-Amz-S3session-Token'] = self.credentials.token
        # Now parse the original query string to a dict, inject our new query
        # params, and serialize back to a query string.
        url_parts = urlsplit(request.url)
        # parse_qs makes each value a list, but in our case we know we won't
        # have repeated keys so we know we have single element lists which we
        # can convert back to scalar values.
        query_string_parts = parse_qs(url_parts.query, keep_blank_values=True)
        query_dict = {k: v[0] for k, v in query_string_parts.items()}

        if request.params:
            query_dict.update(request.params)
            request.params = {}
        # The spec is particular about this.  It *has* to be:
        # https://<endpoint>?<operation params>&<auth params>
        # You can't mix the two types of params together, i.e just keep doing
        # new_query_params.update(op_params)
        # new_query_params.update(auth_params)
        # percent_encode_sequence(new_query_params)
        operation_params = ''
        if request.data:
            # We also need to move the body params into the query string. To
            # do this, we first have to convert it to a dict.
            query_dict.update(_get_body_as_dict(request))
            request.data = ''
        if query_dict:
            operation_params = percent_encode_sequence(query_dict) + '&'
        new_query_string = (
            f"{operation_params}{percent_encode_sequence(auth_params)}"
        )
        # url_parts is a tuple (and therefore immutable) so we need to create
        # a new url_parts with the new query string.
        # <part>   - <index>
        # scheme   - 0
        # netloc   - 1