Help needed with translating perl to python

[vj]

I have a perl script which connect to network stream using sockets.
The scripts first logins in to the server and then parses the data
comming from the socket.

Statement 1:
  my $today = sprintf("%4s%02s%02s", [localtime()]->[5]+1900,
[localtime()]->[4]+1, [localtime()]->[3]) ;


Statement 2:
  my $password = md5_hex("$today$username") ;

Statement group 3:

$msglen = bcdlen(length($msg)) ;

sub bcdlen {
  my $strlen = sprintf("%04s", shift) ;
  my $firstval = substr($strlen, 2, 1)*16 + substr($strlen, 3, 1) ;
  my $lastval  = substr($strlen, 0, 1)*16 + substr($strlen, 1, 1) ;
  return chr($firstval) . chr($lastval) ;
}