iOS AirPrint without a true AirPrint compatible device

My latest iOS mission has been to enable Apple AirPrint introduced in iOS 4.2 to work with non AirPrint printers. At the time of writing I am only aware of HP printers that are AirPrint compatible out if the box; therein lies the problem since poor experience with HP and Canon consumer printers in the 90's has left me a staunch Epson owner ever since. 


Epson at the moment have no AirPrint enabled devices available and have taken the stance that they will not be retrospectively updating firmware for existing models to enable AirPrint support. I've only recently acquired several variants of the Epson SX600FW family which have been great to date, so being keen to maximise their potential I spent an hour or two 'enabling' AirPrint compatibility using an Ubuntu server to act as an AirPrint server. Read on... 

Setup

• Epson SX600FW connected wirelessly to a WRT-54GL router
• iPhone 3GS running iOS 4.3.3
• Ubuntu 10.04 server which acts as the AirPrint server

My point of reference was this blog by Ryan Finnie that researched and walks through AirPrint and Linux in a lot more detail than I am about too. This AirPrint solution cannot be installed onto the Epson printer at this time but relies on a separate Ubuntu server to listen for the AirPrint jobs and to send them to the printer.


Here's what to do:


1. Add your printer to the Ubuntu Server

• Goto System > Administration > Printing > And click Add Printer.
• Select ‘Network Printer’ and 'Find Network Printer'
• For me Ubuntu then automatically found and installed the appropriate driver, your mileage may vary
• Eventually click ‘Apply’ to finish.

 2. Check that CUPS is in installed, if not you will need to install CUPS. You will need to have a PDF filter working correctly. Debian (Ubuntu) seems to provide this out of the box with a CUPS install;
dpkg -s cups | grep Status
sudo apt-get install cups


3. Go into the CUPS interface which should be here: http://localhost:631/admin

Enable the following options:

• Show printers shared by other systems
• Share printers connected to this system
• Allow printing from the Internet
• Allow remote administration
• Allow users to cancel any job (not just their own) 

4. Edit the CUPS configuration file;

sudo gedit /etc/cups/cupsd.conf

Add the following lines: 

ServerAlias *

Change the following lines:
Port Localhost:631 to Port 631
BrowseAllow to BrowseAllow All

5. Check that Avahi is installed, if not you will need to install Avahi-daemon;

dpkg -s Avahi-daemon | grep Status

sudo apt-get install avahi-daemon

6. Restart CUPS to get it to publish printer services. (AirPrint will not be using the CUPS-published services, but we will need them to recreate a manual service.)

sudo /etc/init.d/cups restart

7. Generate the AirPrint Avahi service files for CUPS printers. TJ Fontaine has created a great script that automates the creation of the service files see automatically generate AirPrint Avahi service files for CUPS printers  for the detail, the actual script is here airprint-generate script.
airprint-generate.py  


8. Move the generated AirPrint Avahi services files to the Avahi folder;
sudo mv AirPrint-Epson-Stylus-SX600FW.service /etc/avahi/services/AirPrint-Epson-Stylus-SX600FW.service


9. Restart CUPS and Avahi;
 sudo /etc/init.d/cups restart
sudo restart avahi-daemon


10. Print! on your iPhone/iPad, go into an application (Safari, for example), print, and search for printers. Your new printer definition should be in there.



If you found this post helpful you may enjoy this post which talks through AirPlay on Ubuntu with iOS devices.


Kudos to Ryan Finnie for his initial research and TJ Fontaine the great AirPrint services script.
TJ Fontaine's AirPrint services python script is below for reference in case the link dies.

#!/usr/bin/env python

"""
Copyright (c) 2010 Timothy J Fontaine <tjfontaine@atxconsulting.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""

import cups, os, optparse, re, urlparse
import os.path
from StringIO import StringIO

from xml.dom.minidom import parseString
from xml.dom import minidom

import sys

try:
import lxml.etree as etree
from lxml.etree import Element, ElementTree, tostring
except:
try:
from xml.etree.ElementTree import Element, ElementTree, tostring
etree = None
except:
try:
from elementtree import Element, ElementTree, tostring
etree = None
except:
raise 'Failed to find python libxml or elementtree, please install one of those or use python >= 2.5'

XML_TEMPLATE = """<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
<name replace-wildcards="yes"></name>
<service>
<type>_ipp._tcp</type>
<subtype>_universal._sub._ipp._tcp</subtype>
<port>631</port>
<txt-record>txtvers=1</txt-record>
<txt-record>qtotal=1</txt-record>
<txt-record>Transparent=T</txt-record>
<txt-record>URF=none</txt-record>
</service>
</service-group>"""

#TODO XXX FIXME
#<txt-record>ty=AirPrint Ricoh Aficio MP 6000</txt-record>
#<txt-record>Binary=T</txt-record>
#<txt-record>Duplex=T</txt-record>
#<txt-record>Copies=T</txt-record>


DOCUMENT_TYPES = {
# These content-types will be at the front of the list
'application/pdf': True,
'application/postscript': True,
'application/vnd.cups-raster': True,
'application/octet-stream': True,
'image/urf': True,
'image/png': True,
'image/tiff': True,
'image/png': True,
'image/jpeg': True,
'image/gif': True,
'text/plain': True,
'text/html': True,

# These content-types will never be reported
'image/x-xwindowdump': False,
'image/x-xpixmap': False,
'image/x-xbitmap': False,
'image/x-sun-raster': False,
'image/x-sgi-rgb': False,
'image/x-portable-pixmap': False,
'image/x-portable-graymap': False,
'image/x-portable-bitmap': False,
'image/x-portable-anymap': False,
'application/x-shell': False,
'application/x-perl': False,
'application/x-csource': False,
'application/x-cshell': False,
}

class AirPrintGenerate(object):
def __init__(self, host=None, user=None, port=None, verbose=False,
directory=None, prefix='AirPrint-', adminurl=False):
self.host = host
self.user = user
self.port = port
self.verbose = verbose
self.directory = directory
self.prefix = prefix
self.adminurl = adminurl

if self.user:
cups.setUser(self.user)

def generate(self):
if not self.host:
conn = cups.Connection()
else:
if not self.port:
self.port = 631
conn = cups.Connection(self.host, self.port)

printers = conn.getPrinters()

for p, v in printers.items():
if v['printer-is-shared']:
attrs = conn.getPrinterAttributes(p)
uri = urlparse.urlparse(v['printer-uri-supported'])

tree = ElementTree()
tree.parse(StringIO(XML_TEMPLATE.replace('\n', '').replace('\r', '').replace('\t', '')))

name = tree.find('name')
name.text = 'AirPrint %s @ %%h' % (p)

service = tree.find('service')

port = service.find('port')
port_no = None
if hasattr(uri, 'port'):
port_no = uri.port
if not port_no:
port_no = self.port
if not port_no:
port_no = cups.getPort()
port.text = '%d' % port_no

if hasattr(uri, 'path'):
rp = uri.path
else:
rp = uri[2]

re_match = re.match(r'^//(.*):(\d+)(/.*)', rp)
if re_match:
rp = re_match.group(3)

#Remove leading slashes from path
#TODO XXX FIXME I'm worried this will match broken urlparse
#results as well (for instance if they don't include a port)
#the xml would be malform'd either way
rp = re.sub(r'^/+', '', rp)

path = Element('txt-record')
path.text = 'rp=%s' % (rp)
service.append(path)

desc = Element('txt-record')
desc.text = 'note=%s' % (v['printer-info'])
service.append(desc)

product = Element('txt-record')
product.text = 'product=(GPL Ghostscript)'
service.append(product)

state = Element('txt-record')
state.text = 'printer-state=%s' % (v['printer-state'])
service.append(state)

ptype = Element('txt-record')
ptype.text = 'printer-type=%s' % (hex(v['printer-type']))
service.append(ptype)

pdl = Element('txt-record')
fmts = []
defer = []

for a in attrs['document-format-supported']:
if a in DOCUMENT_TYPES:
if DOCUMENT_TYPES[a]:
fmts.append(a)
else:
defer.append(a)

fmts = ','.join(fmts+defer)

dropped = []

# TODO XXX FIXME all fields should be checked for 255 limit
while len('pdl=%s' % (fmts)) >= 255:
(fmts, drop) = fmts.rsplit(',', 1)
dropped.append(drop)

if len(dropped) and self.verbose:
sys.stderr.write('%s Losing support for: %s%s' % (p, ','.join(dropped), os.linesep))

pdl.text = 'pdl=%s' % (fmts)
service.append(pdl)

if self.adminurl:
admin = Element('txt-record')
admin.text = 'adminurl=%s' % (v['printer-uri-supported'])
service.append(admin)

fname = '%s%s.service' % (self.prefix, p)

if self.directory:
fname = os.path.join(self.directory, fname)

f = open(fname, 'w')

if etree:
tree.write(f, pretty_print=True, xml_declaration=True, encoding="UTF-8")
else:
xmlstr = tostring(tree.getroot())
doc = parseString(xmlstr)
dt= minidom.getDOMImplementation('').createDocumentType('service-group', None, 'avahi-service.dtd')
doc.insertBefore(dt, doc.documentElement)
doc.writexml(f)
f.close()

if self.verbose:
sys.stderr.write('Created: %s%s' % (fname, os.linesep))

if __name__ == '__main__':
parser = optparse.OptionParser()
parser.add_option('-H', '--host', action="store", type="string",
dest='hostname', help='Hostname of CUPS server (optional)', metavar='HOSTNAME')
parser.add_option('-P', '--port', action="store", type="int",
dest='port', help='Port number of CUPS server', metavar='PORT')
parser.add_option('-u', '--user', action="store", type="string",
dest='username', help='Username to authenticate with against CUPS',
metavar='USER')
parser.add_option('-d', '--directory', action="store", type="string",
dest='directory', help='Directory to create service files',
metavar='DIRECTORY')
parser.add_option('-v', '--verbose', action="store_true", dest="verbose",
help="Print debugging information to STDERR")
parser.add_option('-p', '--prefix', action="store", type="string",
dest='prefix', help='Prefix all files with this string', metavar='PREFIX',
default='AirPrint-')
parser.add_option('-a', '--admin', action="store_true", dest="adminurl",
help="Include the printer specified uri as the adminurl")

(options, args) = parser.parse_args()

# TODO XXX FIXME -- if cups login required, need to add
# air=username,password
from getpass import getpass
cups.setPasswordCB(getpass)

if options.directory:
if not os.path.exists(options.directory):
os.mkdir(options.directory)

apg = AirPrintGenerate(
user=options.username,
host=options.hostname,
port=options.port,
verbose=options.verbose,
directory=options.directory,
prefix=options.prefix,
adminurl=options.adminurl,
)

apg.generate()