To Know Filesize Without Content-Length !!

I make a program to know every filesize from remote server. But i have a
problem when there is many remote server that didn't send Content-Length.
The thing that i want to ask is : 
" Is there any way to know how many is the filesize for a file when the
remote server didn't send Content-Length header ?? And also is there any
file from remote server that i couldn't get the filesize with all method
?? " 


Thanks For All Attention
Ronny