--AaB03x
content-disposition: form-data; name="field1"

value1
--AaB03x
content-disposition: form-data; name="field2"

value2
--AaB03x
content-disposition: form-data; name="userfile"; filename="filename"
Content-Type: text/plain
Content-Transfer-Encoding: binary

test
--AaB03x--
