Initial public version.

README.md

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+printer-browser.py
+==================
+
+Small program to browse the local network for printers via
+Apple-flavored mDNS (Bonjour), massage the data slightly, and write
+it out in DNS master file format.
+
+Changes made to the data:
+
+* We strip off the `.local.` suffix, because we want to append the
+  local zone `$ORIGIN` when we drop this text into a master file.
+
+* We remove the adminurl property, because we don't generally want our
+  users trying to reconfigure our printers anyway.
+
+The target audience for this is the IETF meeting network, but this
+might conceivably be useful whenever trying to make AirPrint work
+across multiple network segments.
+
+Most of the work is done by two external packages: `zeroconf` and
+`dnspython`.  Both of these are available from PyPi, as well as from
+various OS-specific packaging systems.
+
+In theory this code is Python-version-agnostic, and should run under
+either Python 2 or Python 3.
+
+Current usage as of this writing (run with `--help` for latest):
+
+```
+usage: printer_browser.py [-h] [-q] [-o OUTPUT]
+                          [--browse-timeout BROWSE_TIMEOUT]
+                          [--query-timeout QUERY_TIMEOUT] [--keep-adminurl]
+                          [mdns_type [mdns_type ...]]
+
+Browse for printers on the local net, dump DNS records for inclusion in a DNS
+zone in master file format.
+
+positional arguments:
+  mdns_type             mDNS types for which to browse (default:
+                        ['_ipp._tcp.local.', '_pdl-datastream._tcp.local.'])
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -q, --quiet           omit comments from generated master file text
+                        (default: False)
+  -o OUTPUT, --output OUTPUT
+                        where to write master file text (default: -)
+  --browse-timeout BROWSE_TIMEOUT
+                        timeout in seconds while browsing for printers
+                        (default: 5)
+  --query-timeout QUERY_TIMEOUT
+                        timeout in seconds to retrieve printer data (default:
+                        3)
+  --keep-adminurl       keep adminurl property in generated DNS data (default:
+                        False)
+```

printer_browser.py

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+#!/usr/bin/env python3
+
+"""
+Browse for printers on the local net, dump DNS records for inclusion
+in a DNS zone in master file format.
+"""
+
+
+from argparse           import ArgumentParser, FileType, ArgumentDefaultsHelpFormatter
+from zeroconf           import Zeroconf, ServiceBrowser, ServiceInfo
+from socket             import inet_ntop, AF_INET, AF_INET6
+from dns.rdataclass     import IN
+from dns.rdatatype      import PTR, SRV, TXT
+from dns.rrset          import RRset
+
+class Listener:
+    """
+    mDNS browser, receives service advertisements, retrieves
+    ServiceInfo records and drops them into a Queue for pickup.
+    """
+
+    try:
+        from queue import Queue, Empty # Python 3
+    except ImportError:
+        from Queue import Queue, Empty # Python 2
+
+    def __init__(self, args):
+        self.q = self.Queue()
+        self.browse_timeout = args.browse_timeout
+        self.query_timeout  = args.query_timeout * 1000
+
+    def add_service(self, z, type, name):
+        printer = z.get_service_info(type, name, timeout = self.query_timeout)
+        if printer is not None:
+            self.q.put(printer)
+
+    def remove_service(self, z, type, name):
+        pass
+
+    def get(self):
+        "Iterator to retrieve ServiceInfo results"
+        while True:
+            try:
+                yield self.q.get(timeout = self.browse_timeout)
+            except self.Empty:
+                return
+
+def dns_name(name, prefix = (), suffix = ()):
+    "Strip .local, add optional prefix and suffix."
+    from dns.name import Name, from_text
+    name = from_text(str(name))
+    assert name.labels[-2:] == (b"local", b"")
+    return Name(prefix + name.labels[:-2] + suffix)
+
+def rr(name, rdata):
+    r = RRset(name, rdata.rdclass, rdata.rdtype)
+    r.add(rdata)
+    return r
+
+def txt_rr(printer):
+    "Regenerate ServiceInfo from property list and generate a TXT RR."
+    from dns.rdata import from_wire
+    si = ServiceInfo(printer.type, printer.name, properties = printer.properties)
+    return rr(dns_name(printer.name), from_wire(IN, TXT, si.text, 0, len(si.text)))
+
+def srv_rr(printer):
+    "Generate an SRV RR."
+    from dns.rdtypes.IN.SRV import SRV as SRV_RR
+    return rr(dns_name(printer.name), SRV_RR(IN, SRV, printer.priority, printer.weight, printer.port, dns_name(printer.server)))
+
+def ptr_rr(printer, *prefix):
+    "Generate a PTR RR."
+    from dns.rdtypes.ANY.PTR import PTR as PTR_RR
+    return rr(dns_name(printer.type, prefix = prefix), PTR_RR(IN, PTR, dns_name(printer.name)))
+
+def main():
+    ap = ArgumentParser(description = __doc__, formatter_class = ArgumentDefaultsHelpFormatter)
+    ap.add_argument("-q", "--quiet",    action = "store_true",
+                    help = "omit comments from generated master file text")
+    ap.add_argument("-o", "--output",   type = FileType("w"),   default = "-",
+                    help = "where to write master file text")
+    ap.add_argument("--browse-timeout", type = int,             default = 5,
+                    help = "timeout in seconds while browsing for printers")
+    ap.add_argument("--query-timeout",  type = int,             default = 3,
+                    help = "timeout in seconds to retrieve printer data")
+    ap.add_argument("--keep-adminurl",  action = "store_true",
+                    help = "keep adminurl property in generated DNS data")
+    ap.add_argument("mdns_type",        nargs = "*",
+                    default = ["_ipp._tcp.local.", "_universal._sub._ipp._tcp.local.", "_pdl-datastream._tcp.local."],
+                    help = "mDNS types for which to browse")
+    args = ap.parse_args()
+
+    def write(s = ""):
+        args.output.write("{!s}\n".format(s))
+
+    printers = {}
+
+    z = Zeroconf()
+    listener = Listener(args)
+    for mdns_type in args.mdns_type:
+        ServiceBrowser(z, mdns_type, listener)
+    for printer in listener.get():
+        try:
+            printers[printer.name].append(printer)
+        except KeyError:
+            printers[printer.name] = [printer]
+    z.close()
+
+    for printer in printers.values():
+        rrs = [ptr_rr(p) for p in printer]
+        p = printer[0]
+        if not args.keep_adminurl:
+            p.properties.pop(b"adminurl", None)
+        rrs.append(srv_rr(p))
+        rrs.append(txt_rr(p))
+
+        if not args.quiet:
+            addr = inet_ntop({4:AF_INET, 6:AF_INET6}[len(p.address)], p.address)
+            write(";; Name: {!r}".format(p.name))
+            write(";; Addr: {} ({})".format(addr, p.server))
+            write(";;")
+        for rr in rrs:
+            write(rr)
+        write()
+
+if __name__ == "__main__":
+    main()