URL Valid Resource?

Received URL Valid?

• User-agent of header request
• Referer of header request
• IP of request
• Expiry of url

When you send HTTP request -> Extracting HTML -> receive URL.

Is This URL Valid?

Something URL Resource closely related with sent Request.

And URL Resource default is valid on some catch conditions.

But also often that: this url is public and valid.

We are only talking about:

1. URL Resource closely related with sent Request.
2. URL Resource default is valid on some catch conditions.

1. URL Resource closely related with sent Request

Req 1 => .... => Receive: URL A.

Req 2 -->  |

Req 3 -->  |  URL A
Req 4 -->  |

Server A check Ip and block req 2, req 3, .. => create "Leech URL" on server (where send Req 1)
URL A has expiry date => req2, req3, .. need sooner.

2. URL Resource default is valid on some catch conditions.

URL A is valid when header "referer" of request is a condition value.

Eg:
REQUEST 1 send to URL A, Server A procced and then return URL of resource: URL B. URL B valid if request has header referer A

Why is this important?
Because: sometimes url of resource has format:

/<id of resource>_<extra option> (but this is encode.)

Some experienced programmer can decode and has "navtive function":

f(id resource, force option) => url resource.

This url is powerful if: its server not check "referer" of request header.

Please wait next!