WAF / Client / update_size_constraint_set

update_size_constraint_set#

WAF.Client.update_size_constraint_set(**kwargs)#

Note

This is AWS WAF Classic documentation. For more information, see AWS WAF Classic in the developer guide.

For the latest version of AWS WAF, use the AWS WAFV2 API and see the AWS WAF Developer Guide. With the latest version, AWS WAF has a single set of endpoints for regional and global use.

Inserts or deletes SizeConstraint objects (filters) in a SizeConstraintSet. For each SizeConstraint object, you specify the following values:

  • Whether to insert or delete the object from the array. If you want to change a SizeConstraintSetUpdate object, you delete the existing object and add a new one.

  • The part of a web request that you want AWS WAF to evaluate, such as the length of a query string or the length of the User-Agent header.

  • Whether to perform any transformations on the request, such as converting it to lowercase, before checking its length. Note that transformations of the request body are not supported because the AWS resource forwards only the first 8192 bytes of your request to AWS WAF. You can only specify a single type of TextTransformation.

  • A ComparisonOperator used for evaluating the selected part of the request against the specified Size, such as equals, greater than, less than, and so on.

  • The length, in bytes, that you want AWS WAF to watch for in selected part of the request. The length is computed after applying the transformation.

For example, you can add a SizeConstraintSetUpdate object that matches web requests in which the length of the User-Agent header is greater than 100 bytes. You can then configure AWS WAF to block those requests.

To create and configure a SizeConstraintSet, perform the following steps:

  • Create a SizeConstraintSet. For more information, see CreateSizeConstraintSet.

  • Use GetChangeToken to get the change token that you provide in the ChangeToken parameter of an UpdateSizeConstraintSet request.

  • Submit an UpdateSizeConstraintSet request to specify the part of the request that you want AWS WAF to inspect (for example, the header or the URI) and the value that you want AWS WAF to watch for.

For more information about how to use the AWS WAF API to allow or block HTTP requests, see the AWS WAF Developer Guide.

See also: AWS API Documentation

Request Syntax

response = client.update_size_constraint_set(
    SizeConstraintSetId='string',
    ChangeToken='string',
    Updates=[
        {
            'Action': 'INSERT'|'DELETE',
            'SizeConstraint': {
                'FieldToMatch': {
                    'Type': 'URI'|'QUERY_STRING'|'HEADER'|'METHOD'|'BODY'|'SINGLE_QUERY_ARG'|'ALL_QUERY_ARGS',
                    'Data': 'string'
                },
                'TextTransformation': 'NONE'|'COMPRESS_WHITE_SPACE'|'HTML_ENTITY_DECODE'|'LOWERCASE'|'CMD_LINE'|'URL_DECODE',
                'ComparisonOperator': 'EQ'|'NE'|'LE'|'LT'|'GE'|'GT',
                'Size': 123
            }
        },
    ]
)
Parameters:

  • SizeConstraintSetId (string) –

    [REQUIRED]

    The SizeConstraintSetId of the SizeConstraintSet that you want to update. SizeConstraintSetId is returned by CreateSizeConstraintSet and by ListSizeConstraintSets.

  • ChangeToken (string) –

    [REQUIRED]

    The value returned by the most recent call to GetChangeToken.

  • Updates (list) –

    [REQUIRED]

    An array of SizeConstraintSetUpdate objects that you want to insert into or delete from a SizeConstraintSet. For more information, see the applicable data types:

    • SizeConstraintSetUpdate: Contains Action and SizeConstraint

    • SizeConstraint: Contains FieldToMatch, TextTransformation, ComparisonOperator, and Size

    • FieldToMatch: Contains Data and Type

    • (dict) –

      Note

      This is AWS WAF Classic documentation. For more information, see AWS WAF Classic in the developer guide.

      For the latest version of AWS WAF, use the AWS WAFV2 API and see the AWS WAF Developer Guide. With the latest version, AWS WAF has a single set of endpoints for regional and global use.

      Specifies the part of a web request that you want to inspect the size of and indicates whether you want to add the specification to a SizeConstraintSet or delete it from a SizeConstraintSet.

      • Action (string) – [REQUIRED]

        Specify INSERT to add a SizeConstraintSetUpdate to a SizeConstraintSet. Use DELETE to remove a SizeConstraintSetUpdate from a SizeConstraintSet.

      • SizeConstraint (dict) – [REQUIRED]

        Specifies a constraint on the size of a part of the web request. AWS WAF uses the Size, ComparisonOperator, and FieldToMatch to build an expression in the form of “ Size ComparisonOperator size in bytes of FieldToMatch”. If that expression is true, the SizeConstraint is considered to match.

        • FieldToMatch (dict) – [REQUIRED]

          Specifies where in a web request to look for the size constraint.

          • Type (string) – [REQUIRED]

            The part of the web request that you want AWS WAF to search for a specified string. Parts of a request that you can search include the following:

            • HEADER: A specified request header, for example, the value of the User-Agent or Referer header. If you choose HEADER for the type, specify the name of the header in Data.

            • METHOD: The HTTP method, which indicated the type of operation that the request is asking the origin to perform. Amazon CloudFront supports the following methods: DELETE, GET, HEAD, OPTIONS, PATCH, POST, and PUT.

            • QUERY_STRING: A query string, which is the part of a URL that appears after a ? character, if any.

            • URI: The part of a web request that identifies a resource, for example, /images/daily-ad.jpg.

            • BODY: The part of a request that contains any additional data that you want to send to your web server as the HTTP request body, such as data from a form. The request body immediately follows the request headers. Note that only the first 8192 bytes of the request body are forwarded to AWS WAF for inspection. To allow or block requests based on the length of the body, you can create a size constraint set. For more information, see CreateSizeConstraintSet.

            • SINGLE_QUERY_ARG: The parameter in the query string that you will inspect, such as UserName or SalesRegion. The maximum length for SINGLE_QUERY_ARG is 30 characters.

            • ALL_QUERY_ARGS: Similar to SINGLE_QUERY_ARG, but rather than inspecting a single parameter, AWS WAF will inspect all parameters within the query for the value or regex pattern that you specify in TargetString.

          • Data (string) –

            When the value of Type is HEADER, enter the name of the header that you want AWS WAF to search, for example, User-Agent or Referer. The name of the header is not case sensitive.

            When the value of Type is SINGLE_QUERY_ARG, enter the name of the parameter that you want AWS WAF to search, for example, UserName or SalesRegion. The parameter name is not case sensitive.

            If the value of Type is any other value, omit Data.

        • TextTransformation (string) – [REQUIRED]

          Text transformations eliminate some of the unusual formatting that attackers use in web requests in an effort to bypass AWS WAF. If you specify a transformation, AWS WAF performs the transformation on FieldToMatch before inspecting it for a match.

          You can only specify a single type of TextTransformation.

          Note that if you choose BODY for the value of Type, you must choose NONE for TextTransformation because CloudFront forwards only the first 8192 bytes for inspection.

          NONE

          Specify NONE if you don’t want to perform any text transformations.

          CMD_LINE

          When you’re concerned that attackers are injecting an operating system command line command and using unusual formatting to disguise some or all of the command, use this option to perform the following transformations:

          • Delete the following characters: “ ‘ ^

          • Delete spaces before the following characters: / (

          • Replace the following characters with a space: , ;

          • Replace multiple spaces with one space

          • Convert uppercase letters (A-Z) to lowercase (a-z)

          COMPRESS_WHITE_SPACE

          Use this option to replace the following characters with a space character (decimal 32):

          • f, formfeed, decimal 12

          • t, tab, decimal 9

          • n, newline, decimal 10

          • r, carriage return, decimal 13

          • v, vertical tab, decimal 11

          • non-breaking space, decimal 160

          COMPRESS_WHITE_SPACE also replaces multiple spaces with one space.

          HTML_ENTITY_DECODE

          Use this option to replace HTML-encoded characters with unencoded characters. HTML_ENTITY_DECODE performs the following operations:

          • Replaces (ampersand)quot; with "

          • Replaces (ampersand)nbsp; with a non-breaking space, decimal 160

          • Replaces (ampersand)lt; with a “less than” symbol

          • Replaces (ampersand)gt; with >

          • Replaces characters that are represented in hexadecimal format, (ampersand)#xhhhh;, with the corresponding characters

          • Replaces characters that are represented in decimal format, (ampersand)#nnnn;, with the corresponding characters

          LOWERCASE

          Use this option to convert uppercase letters (A-Z) to lowercase (a-z).

          URL_DECODE

          Use this option to decode a URL-encoded value.

        • ComparisonOperator (string) – [REQUIRED]

          The type of comparison you want AWS WAF to perform. AWS WAF uses this in combination with the provided Size and FieldToMatch to build an expression in the form of “ Size ComparisonOperator size in bytes of FieldToMatch”. If that expression is true, the SizeConstraint is considered to match.

          EQ: Used to test if the Size is equal to the size of the FieldToMatch

          NE: Used to test if the Size is not equal to the size of the FieldToMatch

          LE: Used to test if the Size is less than or equal to the size of the FieldToMatch

          LT: Used to test if the Size is strictly less than the size of the FieldToMatch

          GE: Used to test if the Size is greater than or equal to the size of the FieldToMatch

          GT: Used to test if the Size is strictly greater than the size of the FieldToMatch

        • Size (integer) – [REQUIRED]

          The size in bytes that you want AWS WAF to compare against the size of the specified FieldToMatch. AWS WAF uses this in combination with ComparisonOperator and FieldToMatch to build an expression in the form of “ Size ComparisonOperator size in bytes of FieldToMatch”. If that expression is true, the SizeConstraint is considered to match.

          Valid values for size are 0 - 21474836480 bytes (0 - 20 GB).

          If you specify URI for the value of Type, the / in the URI counts as one character. For example, the URI /logo.jpg is nine characters long.

Return type:

dict

Returns:

Response Syntax

{
    'ChangeToken': 'string'
}

Response Structure

  • (dict) –

    • ChangeToken (string) –

      The ChangeToken that you used to submit the UpdateSizeConstraintSet request. You can also use this value to query the status of the request. For more information, see GetChangeTokenStatus.

Exceptions

Examples

The following example deletes a SizeConstraint object (filters) in a size constraint set with the ID example1ds3t-46da-4fdb-b8d5-abc321j569j5.

response = client.update_size_constraint_set(
    ChangeToken='abcd12f2-46da-4fdb-b8d5-fbd4c466928f',
    SizeConstraintSetId='example1ds3t-46da-4fdb-b8d5-abc321j569j5',
    Updates=[
        {
            'Action': 'DELETE',
            'SizeConstraint': {
                'ComparisonOperator': 'GT',
                'FieldToMatch': {
                    'Type': 'QUERY_STRING',
                },
                'Size': 0,
                'TextTransformation': 'NONE',
            },
        },
    ],
)

print(response)

Expected Output:

{
    'ChangeToken': 'abcd12f2-46da-4fdb-b8d5-fbd4c466928f',
    'ResponseMetadata': {
        '...': '...',
    },
}