Implementing AirPrint with DNS-SD

Question

Background

I'm trying to implement AirPrint through static DNS, like documented on http://dns-sd.org/ServerStaticSetup.html. The iPad gets the dns search domain "lan" through DHCP, and I verified that in Settings-WLAN. I think I created all necessary entries in the right places, the iPad however doesn't find my printer or if it happened to find it, it showed a lock after the printers name and didn't print. (iOS version is 6.0.1)

Has anyone here a clue, as to why iOS does not find the printer or if it finds it, why it shows it as locked?

This is my setup (simplified with example domain)

DNS entries

Redirect to browse domain

PTR b._dns-sd._udp.lan = bonjour.lan
PTR lb._dns-sd._udp.lan = bonjour.lan

Printer entries

PTR _ipp._tcp.bonjour.lan = TestPrinter._ipp._tcp.bonjour.lan
PTR _universal._sub._ipp._tcp.bonjour.lan = TestPrinter._ipp._tcp.bonjour.lan
SRV TestPrinter._ipp._tcp.bonjour.lan = 0 0 631 mfp.printer
TXT TestPrinter._ipp._tcp.bonjour.lan  

txtvers=1  
qtotal=1  
rp=Print  
ty=Toshiba MFP  
adminurl=http://mfp.printer  
note=Shared MFP  
priority=0  
product=(Toshiba eStudio 351c)  
printer-state=3  
printer-type=0xC0B0DE  
Transparent=T  
Binary=T  
Fax=F  
Color=T  
Duplex=T  
Staple=F  
Copies=T  
Collate=T  
Punch=F  
Bind=F  
Sort=T  
Scan=T  
pdl=application/octet-stream,application/pdf,application/postscript,image/jpeg,image/png,image/urf  
URF=none

Answer 1

_{Caveats: I don't own an AirPrint device nor do I have one available elsewhere for testing. So I'm not talking from my own experience in the following answer...}

---

1. First, when publishing a printer (AirPrint or not) from a DNS server ("static, Wide Area Bonjour"), you should include ALL of the TXT record key/value pairs which are listed in the current Bonjour Printing specification.

   A tabular overview is listed in chapter 9 of the specification document (for all details please read the complete chapter):

   

2. Second, the Bonjour Printing specification requires that for a printer you always have to register the LPD protocol (_printer._tcp), even if the device does not support it (port = 0) !.

   The reason for this seemingly braindead requirement is this: LPD is considered the "flagship" protocol for service discovery related to printing. (Meaning: if you own the service instance name for _printer then you also own it for _pdl-datastream, _ipp, _ipps, etc.)

   Some older versions of OS X enforced this. They would not work without it. Newer versions (and probably the next macOS version too) are less dogmatic and more pragmatic...

   In your case the air (has nothing to do with AirPrint, but means s.th. like authentication information required), TLS, UUID, usb_MFG, usb_CMD and usb_MDL keys are missing (even if you'd use "" as their key values).

3. Third, please take to heart the general rule about the trailing dot for domain names. Details are outlined here:

   • dns-sd.org/TrailingDotsInDomainNames.html

4. Fourth, maybe you also should enclose your key values in quotes. Example:

   pdl="application/pdf,image/urf"
   

   not

   pdl=application/pdf,image/urf
   

5. Fifth, in general, what is quoted above in the OP code block does not look like a valid format for a zone file to me. (I notice that the original question has been edited by other people than the OP, so I won't comment on the details...)

Answer 2

Answering 10 years later because this was still one of the first search results I found, and it wasn't quite enough to get me to a working config.

First, the ServerStaticSetup page you previously linked now (if it didn't before) has a section at the bottom with a subtitle "How to set up Wide-Area AirPrint" which covers the basics pretty well.

Second, the link in @Kurt Pfeifle's response to the AirPrint / Bonjour Printing standard on apple.com have broken, but this one works as of now: https://developer.apple.com/bonjour/printing-specification/bonjourprinting-1.2.1.pdf

It seems you need at minimum the following:

• the "browse" PTR record for your domain
• your DNS client configured to search in that domain
  • -OR- a reverse-lookup record for lb._dns-sd._udp, in the "domain" of your in-addr.arpa entry
    • e.g. if your device's IP is 1.2.3.4, you need a record like lb._dns-sd._udp.4.3.2.1.in-addr.arpa. PTR yourdomain.tld
• an LPR / _printer PTR record and corresponding SRV record
  • the SRV record can (and likely should) point to port 0
• a PDL / _pdl-datastream PTR and corresponding SRV record
• a PDL TXT record
• an IPP / _ipp PTR and corresponding SRV record
• an IPP TXT record
• an IPP.URF / _universal._sub._ipp PTR record (pointing at the IPP SRV/TXT domain name)

I reaped the contents needed for the TXT records from mDNS broadcasts coming from the printer, using a machine on the same local wifi network.

• On Linux (with avahi installed) you can use sudo killall -USR1 avahi-daemon to dump all records it knows about in zone file format to syslog.
  • It's kind of annoying to extract that from syslog, so I used avahi-browse -d local -a -r -t to get the same data formatted slightly differently.
• On Mac and Windows (with Bonjour installed) you can use the dns-sd -Z <name> command to dump individual records in zone file format.

I'm using DNSMasq, with an HP 8020 series MFP, and this configuration is currently working from the DNS server side:

ptr-record=b._dns-sd._udp.domain.tld,domain.tld
ptr-record=lb._dns-sd._udp.domain.tld,domain.tld

address=/basement-printer.domain.tld/,1.2.3.4

# LPR *must* be advertised, but setting port to 0 shows it's not supported
ptr-record=_printer._tcp.domain.tld,basement-printer._printer._tcp.domain.tld
srv-host=basement-printer._printer._tcp.domain.tld,basement-printer.domain.tld,0

# IPP on port 631
ptr-record=_ipp._tcp.domain.tld,basement-printer._ipp._tcp.domain.tld
# must also advertise URF / _universal for AirPrint to auto-find us
ptr-record=_universal._sub._ipp._tcp.domain.tld,basement-printer._ipp._tcp.domain.tld
srv-host=basement-printer._ipp._tcp.domain.tld,basement-printer.domain.tld,631
txt-record=basement-printer._ipp._tcp.domain.tld,"Fax=T","rfo=ipp/faxout","mopria-certified=2.0","Scan=T","kind=document,envelope,photo,postcard","URF=CP1,MT1-2-8-9-10-11,PQ3-4-5,RS300-600,SRGB24,OB9,OFU0,W8-16,DEVW8-16,DEVRGB24-48,ADOBERGB24-48,DM3,IS1,V1.4,FN3","PaperMax=legal-A4","pdl=application/vnd.hp-PCL,image/jpeg,image/urf,image/pwg-raster,application/PCLm","Duplex=T","Color=T","usb_MDL=OfficeJet Pro 8020 series","usb_MFG=HP","ty=HP OfficeJet Pro 8020 series","product=(HP OfficeJet Pro 8020 series)","UUID=bd06fe8e-e45f-5e04-3ca1-150938ffc67b","rp=ipp/print","TLS=1.2","qtotal=1","priority=30","note=","adminurl=http://HP3024A9686036-783.local./#hId-pgAirPrint","txtvers=1"

# PDL on port 9100
ptr-record=_pdl-datastream._tcp.domain.tld,basement-printer._pdl-datastream._tcp.domain.tld
srv-host=basement-printer._pdl-datastream._tcp.domain.tld,basement-printer.domain.tld,9100
txt-record=basement-printer._pdl-datastream._tcp.domain.tld,"pdl=application/vnd.hp-PCL,image/jpeg,image/urf,image/pwg-raster,application/PCLm","usb_MDL=OfficeJet Pro 8020 series","usb_MFG=HP","mac=DE:AD:BE:EF:DE:AD","UUID=bd06fe8e-e45f-5e04-3ca1-150938ffc67b","priority=40","rp=","txtvers=1"

Finally, because I think others may be doing the same thing-- to configure the DNS search domain for a WireGuard iOS client, you must add it to the "DNS Server" field after a comma... e.g. 1.2.3.4,domain.tld .