was sent to me in POST or GET method.

Blake already gave a perfect answer, but I'd like to add that %ENV is loaded with useful information. Give the following piece of code a try to find out more about this wonderful hash.

use Data::Dumper;
print Dumper \%ENV;
[download]

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk