DS No-Intro Header Patcher

import binascii,os,re,subprocess,sys,urllib,urllib2,zipfile

def CRC32_from_file(filename):
    buf = open(filename,'rb').read()
    buf = (binascii.crc32(buf) & 0xFFFFFFFF)
    return "%08X" % buf

ds_file = sys.argv[1]

crc32 = CRC32_from_file(ds_file)
print crc32

req = urllib2.Request('http://nds.hordeofninjas.com/Header%20Fix/')
opener = urllib2.build_opener()
opener.addheaders =[('User-Agent','Mozilla/5.0 (Windows NT 6.2; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0'),
                    ('Connection','keep-alive')]

try:
    res = opener.open(req)
except urllib2.HTTPError:
    httperror = 1
    exit
html = res.read()

link = re.findall("href=\"(.+?_Old-"+crc32+"_to.+)\">",html,re.IGNORECASE)
try:
    link = 'http://nds.hordeofninjas.com/Header%20Fix/'+link.pop()
except IndexError:
    print 'No patch found'
    sys.exit()

file_name = link.split('/')[-1]
file = open(file_name, 'wb')
res = opener.open(link).read()
file.write(res)
file.close()

zipfile.ZipFile(file_name).extractall()
subprocess.call('del '+file_name, shell=True)

patch = re.findall('(.+?)\.zip',file_name).pop()
ds_file = re.findall('(.+?)\.nds',ds_file).pop()

if os.path.exists(patch+'.xdelta3'):
    subprocess.call('xdelta30u.exe -d -s "'+ds_file+'.nds" "'+patch+'.xdelta3" "'+ds_file+'_patch.nds"', shell=True)
    subprocess.call('del '+patch+'.xdelta3', shell=True)
elif os.path.exists(patch+'.xdelta'):
    subprocess.call('xdelta30u.exe -d -s "'+ds_file+'.nds" "'+patch+'.xdelta" "'+ds_file+'_patch.nds"', shell=True)
    subprocess.call('del '+patch+'.xdelta', shell=True)
else:
    print crap

print 'Done '+ds_file