Apple - Can I list all the Bonjour-enabled services that are running?

The dns-sd command-line tool can be helpful for this, but learning to use it is a bit tricky.

Running dns-sd -B _services._dns-sd._udp will return a list of all available service types that currently being advertised. (The list is per interface, so there will be some redundancy.) If this is done on a Mac with no active network connection, the list will of course only contain services running on that machine.

Using that list, you can request information about the individual services types by running things like dns-sd -B _home-sharing._tcp (which lists iTunes Home Sharing instances), and then, given an instance name, you can run dns-sd -L "Wes Campaigne’s Library" _home-sharing._tcp to lookup information for a particular instance.

To be honest, though, this whole process is rather tedious, and it's exactly what Discovery (formerly Bonjour Browser) was built to do, so I highly recommend using that. Whichever way you do it, though, it may not always be clear what program is responsible for a given service entry.

You can use the strategy given in binarybob's answer to try to map service entries to running processes based on port number, but this may not always work. Another strategy is to run something like dns-sd -B _home-sharing._tcp which remains open and reports when instances are added or removed, then, one by one, quit various apps and (assuming it's not a system service) see which one's quitting triggers the removal message.

Although it might not satisfy your exact criteria, Tildesoft's Bonjour Browser can list all the all the bonjour services advertised on your local network and the hosts that are advertising them.

I guess for locally advertised services you could drill down in Bonjour Browser to find the port number the service is advertised on, then use lsof to determine the application associated with it, For example:

lsof -i | grep 57857

gives

iTunes    36720   ...     TCP *:57857 (LISTEN)

when I have iTunes running.

Although classified as a legacy article, this very may well be what you are looking for: DNSServiceMetaQuery. As outlined by the documentation:

This sample uses DNSServiceQueryRecord to send a Multicast DNS query that returns a list of Bonjour service types being advertised on the local network. Machines must be running mDNSResponder-58.6 (Mac OS X 10.3.4) or later in order to respond to this query.

To run DNSServiceMetaQuery on Mountain Lion (the included build does not run properly), go to the sample code link and click Download Sample Code. Then, install Xcode if you haven't already. Create a new project under the template of Mac OS X > Application > Command Line Tool.

Open and copy all text in ~/Downloads/DNSServiceMetaQuery/DNSServiceMetaQuery.cand paste it into main.c of your new Command Line Tool project (replacing everything that was there in the template). Next, you'll need to add CoreFoundation.framework to the project by clicking the project name in the sidebar > Build Phases and open the dropdown arrow next to Link Binary With Libraries. Click the + button, search for CoreFoundation.framework, and add it. Then click the Run button (looks like a play button) and wait for a Build Succeeded image. Something should come from the button of the window with a log; this will display all of your Bonjour services. Make sure All Output is checked.