DNSServiceBrowse

DNSServiceBrowse is a function in the DNS-SD (Bonjour) API used to discover service instances on a local network. It operates asynchronously and reports findings through a callback as services matching a specified type appear or disappear on the chosen domain.

The function typically takes a DNSServiceRef to manage the ongoing browse, a set of flags, an interface index, the service type to search for (regtype, such as "_http._tcp"), the domain to browse in (often "local." or an empty string for the default local domain), a callback function, and a user-provided context pointer. The call returns a DNSServiceErrorType indicating immediate success or failure; actual results are delivered via the callback.

The browse callback receives information about each discovered service, including the interface, the service name, regtype, and domain. The flags indicate whether a service was added or removed and whether more results are coming in a single callback invocation. When a service is found, applications typically follow up with DNSServiceResolve to obtain the target host and port, and then DNSServiceGetAddrInfo (or similar) to acquire address information.

DNSServiceBrowse is widely used on Apple platforms (macOS, iOS) as part of the Bonjour/mDNS-SD framework to locate printers, media servers, cameras, and other network services. It is designed to be used in conjunction with a run loop or dispatch mechanism to process events and to manage the lifecycle of the DNSServiceRef, including proper teardown when browsing is no longer needed.

Overall, DNSServiceBrowse provides the first step in a multi-stage service discovery workflow within the DNS-SD framework.