200 OK\015\012
Some-Header: value\015\012
Other-Header: value\015\012
\015\012
Body\015\012
Body\015\012
Body\015\012

##</code><code>##

# set input operator to CRLF
$/ = "\015\012";

# read header line by line
while ( my $head = <STDIN> ) {
    last if m/^\015\012/;
    # must be a header line
    # do stuff
}

# header finished so read body line-wise
while ( my $body = <STDIN> ) {
    # do whatever
}

##</code><code>##

some very very very very very very
    very very very long single line
    that just keeps on and on and on
    going and going and going
finally we get to a real new line.....