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    CDN:Request processing functions

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    CDN:Request processing functions

    Last Updated:Oct 14, 2024

    This topic describes the syntax, description, parameters, and return values of request processing functions. This topic also provides examples of these functions.

    add_req_header

    The following table describes the details about this function.
    ItemDescription
    Syntaxadd_req_header(name, value [, append])
    DescriptionAdds a request header to requests before they are redirected to the origin server.
    Parameter
    • name: the name of the request header that you want to add. Data type: string.
    • value: the value of the request header that you want to add. Data type: string.
    • append: specifies whether to append a request header with the specified value if a request header with the same name already exists. Valid values: true and false. Default value: false. Data type: Boolean. If you set this parameter to false, the specified value will overwrite the value of the existing request header.
    Return valueReturns true by default and returns false if the specified request header is invalid.
    Example
    add_req_header('USER-DEFINED-REQ-1', '1')
add_req_header('USER-DEFINED-REQ-1', 'x', true)
add_req_header('USER-DEFINED-REQ-2', '2')
del_req_header('USER-DEFINED-REQ-2')

Note: The following request headers are added:
USER-DEFINED-REQ-1: 1
USER-DEFINED-REQ-1: x

The USER-DEFINED-REQ-2 header is added and then deleted. Therefore, the USER-DEFINED-REQ-2 request header is not included in requests that are redirected to the origin server.

    del_req_header

    The following table describes the details about this function.
    ItemDescription
    Syntaxdel_req_header(name)
    DescriptionDeletes a request header from requests before they are redirected to the origin server.
    Parametername: the name of the request header that you want to delete. Data type: string.
    Return valueReturns true by default and returns false if the specified request header is invalid.
    Example
    add_req_header('USER-DEFINED-REQ-1', '1')
add_req_header('USER-DEFINED-REQ-1', 'x', true)
add_req_header('USER-DEFINED-REQ-2', '2')
del_req_header('USER-DEFINED-REQ-2')

Note: The following request headers are added:
USER-DEFINED-REQ-1: 1
USER-DEFINED-REQ-1: x

The USER-DEFINED-REQ-2 header is added and then deleted. Therefore, the USER-DEFINED-REQ-2 request header is not included in requests that are redirected to the origin server.

    add_rsp_header

    The following table describes the details about this function.
    ItemDescription
    Syntaxadd_rsp_header(name, value [, append])
    DescriptionAdds a response header.
    Parameter
    • name: the name of the response header that you want to add. Data type: string.
    • value: the value of the response header that you want to add. Data type: string.
      You can specify one of the following expressions for the value parameter to enable the value to be dynamically replaced in the response phase:
      • ${x}: replaced with the value of ngx.var.x.
      • @{y}: replaced with the value of response header y.
    • append: specifies whether to append a response header with the specified value if a response header with the same name already exists. Valid values: true and false. Default value: false. Data type: Boolean. If you set this parameter to false, the specified value will overwrite the value of the existing response header.
    Return valueReturns true by default and returns false if the specified response header is invalid.
    Example
    add_rsp_header('USER-DEFINED-RSP-1', '1')
add_rsp_header('USER-DEFINED-RSP-1', 'x', true)
add_rsp_header('USER-DEFINED-RSP-2', '2')
del_rsp_header('USER-DEFINED-RSP-2')

Note: The following response headers are added:
USER-DEFINED-RSP-1: 1
USER-DEFINED-RSP-1: x

The USER-DEFINED-RSP-2 header is added and then deleted. Therefore, the USER-DEFINED-RSP-2 header is not included in the responses.

    del_rsp_header

    The following table describes the details about this function.
    ItemDescription
    Syntaxdel_rsp_header(name)
    DescriptionDeletes a response header.
    Parametername: the name of the response header that you want to delete. Data type: string.
    Return valueReturns true by default and returns false if the specified response header is invalid.
    Example
    add_rsp_header('USER-DEFINED-RSP-1', '1')
add_rsp_header('USER-DEFINED-RSP-1', 'x', true)
add_rsp_header('USER-DEFINED-RSP-2', '2')
del_rsp_header('USER-DEFINED-RSP-2')

The following response headers are added:
USER-DEFINED-RSP-1: 1
USER-DEFINED-RSP-1: x

The USER-DEFINED-RSP-2 header is added and then deleted. Therefore, the USER-DEFINED-RSP-2 header is not included in the responses.

    encode_args

    The following table describes the details about this function.
    ItemDescription
    Syntaxencode_args(d)
    DescriptionConverts the k/v pairs in the dictionary specified by d to a URI-encoded string in the format of k1=v1&k2=v2.
    Parameterd: the dictionary that you want to convert.
    Return valueReturns a URI-encoded string.
    Example
    my_args = []
set(my_args, 'signature', 'da9dc4b7-87ae-4330-aaaf-e5454e2c2af1')
set(my_args, 'algo', 'private sign1')
my_args_str = encode_args(my_args)
add_rsp_header('X-DSL-ENCODE-ARGS', my_args_str)

to_args = decode_args(my_args_str)
if get(to_args, 'algo') {
    add_rsp_header('X-DSL-DECODE-ARGS-ALGO', get(to_args, 'algo'))
}
if get(to_args, 'signature') {
    add_rsp_header('X-DSL-DECODE-ARGS-SIGN', get(to_args, 'signature'))
}

Output: The following response headers are added:
X-DSL-ENCODE-ARGS: signature=da9dc4b7-87ae-4330-aaaf-e5454e2c2af1&algo=private%20sign1
X-DSL-DECODE-ARGS-ALGO: private sign1
X-DSL-DECODE-ARGS-SIGN: da9dc4b7-87ae-4330-aaaf-e5454e2c2af1

    decode_args

    The following table describes the details about this function.
    ItemDescription
    Syntaxdecode_args(s)
    DescriptionConverts a URI-encoded string in the format of k1=v1&k2=v2 to a string of dictionary type.
    Parameters: the string that you want to convert.
    Return valueReturns a dictionary object converted from the specified string.
    Example
    my_args = []
set(my_args, 'signature', 'da9dc4b7-87ae-4330-aaaf-e5454e2c2af1')
set(my_args, 'algo', 'private sign1')
my_args_str = encode_args(my_args)
add_rsp_header('X-DSL-ENCODE-ARGS', my_args_str)

to_args = decode_args(my_args_str)
if get(to_args, 'algo') {
    add_rsp_header('X-DSL-DECODE-ARGS-ALGO', get(to_args, 'algo'))
}
if get(to_args, 'signature') {
    add_rsp_header('X-DSL-DECODE-ARGS-SIGN', get(to_args, 'signature'))
}

Output: The following response headers are added:
X-DSL-ENCODE-ARGS: signature=da9dc4b7-87ae-4330-aaaf-e5454e2c2af1&algo=private%20sign1
X-DSL-DECODE-ARGS-ALGO: private sign1
X-DSL-DECODE-ARGS-SIGN: da9dc4b7-87ae-4330-aaaf-e5454e2c2af1

    rewrite

    The following table describes the details about this function.
    ItemDescription
    Syntaxrewrite(url, flag, code)
    DescriptionPerforms a rewrite or redirect operation.
    Parameter
    • url: the URL to which the source URI is rewritten after the rewrite operation. Data type: string.
      • If you set the flag parameter to redirect or break, only the URI is rewritten. This parameter specifies the URI after the rewrite operation.
      • If you set the flag parameter to enhance_redirect or enhance_break, the URI and parameters are rewritten. This parameter specifies the URI and parameters after the rewrite operation.
    • flag: the rewrite mode. Data type: string.
      • redirect: rewrites only the URI. Parameters are not rewritten. By default, a 302 redirect is performed. If you specify this mode, the code parameter is configurable. Valid values for the code parameter are 301, 302 (default), 303, 307, and 308.
      • break: rewrites only the URI to a URL. Parameters are not rewritten.
      • enhance_redirect: similar to redirect. However, both the URI and parameters are rewritten.
      • enhance_break: similar to break. However, both the URI and parameters are rewritten.
    • code: the HTTP status code. Data type: numeric.

      This parameter is available only when you set the flag parameter to redirect or enhance_redirect.

    Return value
    • Returns true by default for a rewrite operation.
    • Does not return values by default for a redirect operation.
    Example
    if and($arg_mode, eq($arg_mode, 'rewrite:enhance_break')) {
  rewrite('/example/examplefile.txt?k=v', 'enhance_break')
}
Note: The URI and parameters of requests redirected to the origin server are rewritten to /example/examplefile.txt?k=v

if and($arg_mode, eq($arg_mode, 'rewrite:enhance_redirect')) {
  rewrite('/example/examplefile.txt?k=v', 'enhance_redirect')
}
if and($arg_mode, eq($arg_mode, 'rewrite:enhance_redirect_301')) {
  rewrite('/example/examplefile.txt?k=v', 'enhance_redirect', 301)
}
Note: A 302 or 301 redirect to /example/examplefile.txt? is performed.k=v

if and($arg_mode, eq($arg_mode, 'rewrite:break')) {
  rewrite('/example/examplefile.txt', 'break')
}
Note: The URI of requests redirected to the origin server is rewritten to /example/examplefile.txt and the original parameters in the requests remain unchanged.

if and($arg_mode, eq($arg_mode, 'rewrite:redirect')) {
  rewrite('/example/examplefile.txt', 'redirect')
}
if and($arg_mode, eq($arg_mode, 'rewrite:redirect_301')) {
  rewrite('/example/examplefile.txt', 'redirect', 301)
}
Note: A 302 or 301 redirect to /example/examplefile.txt is performed and the original parameters remain unchanged.

    say

    The following table describes the details about this function.
    ItemDescription
    Syntaxsay(arg)
    DescriptionPrints a response body and appends a newline character at the end of the output.
    Parameterarg: the content of the response body. Data type: any type.
    Return valueNone.
    Example
    say('hello')
print('byebye')
print('byebye')

Output:
hello
byebyebyebye

    print

    The following table describes the details about this function.
    ItemDescription
    Syntaxprint(arg)
    DescriptionPrints a response body. This function is different from the say() function. This function does not append a newline at the end of the output.
    Parameterarg: the content of the response body. Data type: any type.
    Return valueNone.
    Example
    say('hello')
print('byebye')
print('byebye')

Output:
hello
byebyebyebye

    exit

    The following table describes the details about this function.
    ItemDescription
    Syntaxexit(code [, body])
    DescriptionEnds the current request with the specified code. If you also set the body parameter, a response that includes the specified response body is returned.
    Parameter
    • code: the HTTP status code to return.
    • body: the response body.
    Return valueNone.
    Example
    • Example 1 
      if not($arg_key) {
    exit(403)
}
Note: If a request does not include the key parameter, the request is denied and the HTTP 403 status code is returned. 

if not($cookie_user) {
    exit(403, 'not cookie user')
}
Note: If a request does not include cookie_user, the request is denied and a response that contains the body "not cookie user" is returned with the HTTP 403 status code.

if not(0) {
    exit(403)
}
Note: The not(0) function returns a value of false.

if not(false) {
    exit(403)
}
Note: The not(false) function returns a value of true.
    • Example 2 
      pcs = capture_re($request_uri,'^/([^/]+)/([^/]+)([^?]+)\?(.*)')
sec1 = get(pcs, 1)
sec2 = get(pcs, 2)
sec3 = get(pcs, 3)
if or(not(sec1), not(sec2), not(sec3)) {
   add_rsp_header('X-TENGINE-ERROR', 'auth failed - missing necessary uri set')
   exit(403)
}
digest = md5(concat(sec1, sec3))
if ne(digest, sec2) {
    add_rsp_header('X-TENGINE-ERROR', 'auth failed - invalid digest')
    exit(403)
}

    get_rsp_header

    The following table describes the details about this function.
    ItemDescription
    Syntaxget_rsp_header(str)
    DescriptionObtains a response header.
    Parameterstr: the response header that you want to obtain. Data type: string.
    Return valueReturns the specified response header of string, number, dictionary, or Boolean data type.
    • If the specified response header exists, the response header is returned. The data type of the response header is dictionary or string.
    • If the specified response header does not exist, a value of false is returned.
    Example
    ct = get_rsp_header('content-type')
if ct {
    add_rsp_header('origin-content-type', 'is')
} else {
      add_rsp_header('origin-content-type', 'no')
}

    add_rsp_cookie

    The following table describes the details about this function.
    ItemDescription
    Syntaxadd_rsp_cookie(k, v [,properties])
    DescriptionSets the response cookie. Each time the function is called, a new Set-Cookie response header is generated.
    Parameter
    • k: the name of the cookie.
    • v: the value of the cookie.
    • properties: the properties of the cookie. This parameter is optional. For more information, see Set-Cookie.
    Return valueA value of true is returned if the specified cookie is set and a value of false is returned if the specified cookie failed to be set.
    Example
    add_rsp_cookie('user', 'edgescript')

add_rsp_cookie('login_time', tostring(now()), [
    'path' = '/'
])

expires = cookie_time(time())
add_rsp_cookie('psid', 'SDF93745HFSDF2934JKHG', [
    'path' = '/play',
    'domain' = 'foo.com',
    'secure' = true,
    'httponly' = true,
    'expires' = expires,
    'max_age' = 100,
    'samesite' = 'Strict',
    'extension' = 'xxt3s'
])
    Response:
    Set-Cookie: user=edgescript
Set-Cookie: login_time=1582538968.912; Path=/
Set-Cookie: psid=SDF93745HFSDF2934JKHG; Expires=Mon, 24-Feb-20 10:09:28 GMT; Max-Age=100; Domain=foo.com; Path=/play; Secure; HttpOnly; SameSite=Strict; xxt3s