Ubuntu Manpage: gensio_alloc_mdns, gensio_free_mdns, gensio_mdns_add_service, gensio_mdns_remove

Provided by: libgensio-dev_2.8.2-6.1build1_amd64

NAME

       gensio_alloc_mdns,  gensio_free_mdns, gensio_mdns_add_service, gensio_mdns_remove_service,
       gensio_mdns_add_watch, gensio_mdns_remove_watch - Functions for doing mDNS operations

SYNOPSIS

       #include <gensio/gensio_mdns.h>

       typedef void (*gensio_mdns_done)(struct gensio_mdns *m,
                           void *userdata);

       int gensio_alloc_mdns(struct gensio_os_funcs *o,
                           struct gensio_mdns **m);

       int gensio_free_mdns(struct gensio_mdns *m, gensio_mdns_done done,
                           void *userdata);

       int gensio_mdns_add_service(struct gensio_mdns *m, int interface,
                           int ipdomain, const char *name, const char *type,
                           const char *domain, const char *host,
                           int port, const char *txt[],
                           struct gensio_mdns_service **s);

       typedef void (*gensio_mdns_service_cb)(struct gensio_mdns_service *service,
                           enum gensio_mdns_service_event ev,
                           const char *info,
                           void *cb_data);

       int gensio_mdns_add_service2(struct gensio_mdns *m, int interface,
                           int ipdomain, const char *name, const char *type,
                           const char *domain, const char *host,
                           int port, const char *txt[],
                           gensio_mdns_service_cb cb, void *cb_data,
                           struct gensio_mdns_service **s);

       int gensio_mdns_remove_service(struct gensio_mdns_service *s);

       typedef void gensio_mdns_watch_cb(struct gensio_mdns_watch *w,
                           enum gensio_mdns_data_state state,
                           int interface, int ipdomain,
                           const char *name, const char *type,
                           const char *domain, const char *host,
                           const struct gensio_addr *addr, const char *txt[],
                           void *userdata);

       int gensio_mdns_add_watch(struct gensio_mdns *m, int interface,
                           int ipdomain, const char *name, const char *type,
                           const char *domain, const char *host,
                           gensio_mdns_watch_cb callback, void *userdata,
                           struct gensio_mdns_watch **w);

       int gensio_mdns_remove_watch(struct gensio_mdns_watch *w);

DESCRIPTION

These functions and type deal with mDNS (Multicast DNS) discovery of services on a local
network. They can be used to advertise services or find services. These provide a
powerful and easy to use interface to mDNS capabilities.

To do these things, you must first use gensio_alloc_mdns to allocate an mdns structure
with the standard gensio OS functions structure. You must, of course, do the standard OS
functions wait loops and such. When you are finished, you should free the mdns structure
with gensio_free_mdns. Note that code may still be in mdns callbacks when the free
returns, you have to make sure to wait until the done callback is called to know the code
is out of all callbacks. The done callback is optional if you don't care. Also note that
the mdns will not be freed (and done not called) until all the services and watches are
freed for it.

For the remaining functions, the interface parameter is the system interface number of the
network device, and may be -1 to specify all interfaces. The ipdomain parameter is one
of:

GENSIO_NETTYPE_UNSPEC
Do both IPV4 and IPV4

GENSIO_NETTYPE_IPV4
IPV4 only

GENSIO_NETTYPE_IPV6
IPV6 only

The name, type, domain, and host parameters are the standard mDNS fields, see
documentation on mDNS for details. The txt parameter is for mDNS text fields, and is a
standard argv-like array.

Once you have an mdns structure, you can advertise a service on the net with it using
gensio_mdns_add_service2. That service will continue to be advertised until you call
gensio_mdns_remove_service on it or your program terminates. The domain and host
parameters should generally be NULL to take the system defaults. The txt parameter may be
NULL if you don't have any.

gensio_mdns_add_service2 takes a callback, it will be called when the service has been
registered, and possible with a new name if there was a name conflict. You may pass in a
NULL for the callback if you don't care. The callback parameter can take the following
values:

GENSIO_MDNS_SERVICE_READY
The service is now registered, and the name is the same as the name you passed in.

GENSIO_MDNS_SERVICE_READY_NEW_NAME
The service is now registered, but the name was changed, it will be in the info
parameter.

GENSIO_MDNS_SERVICE_REMOVED
You requested the service be removed, the remove is now complete and the callback
will not be called again.

GENSIO_MDNS_SERVICE_ERROR
An error occurred as part of service registration.

There is a gensio_mdns_add_service function for backwards compatibility, it is equivalent
to calling gensio_mdns_add_service2 with a NULL callback. Don't use it in new code.

To find services on the network, you add a watch with gensio_mdns_add_watch. Any service
that matches your query will be reported with the callback functions and all fields will
be provided in the callback. Once you are done with a watch, you may call
gensio_mdns_remove_watch Note that code may still be in mdns callbacks when the remove
returns, you have to make sure to wait until the done callback is called to know the code
is out of all callbacks. The done callback is optional if you don't care.

Some MDNS libraries do not support an NULL type for the watch, and some do. For portable
code, always specify the watch. If the library does not support a null type the function
will return GE_INCONSISTENT.

The watch callback state has three possible values:

GENSIO_MDNS_WATCH_NEW_DATA
This is a new entry being reported.

GENSIO_MDNS_WATCH_DATA_GONE
An entry that was previously reported as gone away.

GENSIO_MDNS_WATCH_ALL_FOR_NOW
This is called one time after the watch is created, it reports that all currently
known entries have been reported. New ones may be reported in the future, but
those will have been dynamically added later.

In the watch callback, you must make copies of all the strings and addresses passed to you
to keep them. Their continued existence is not guaranteed.

In watches, all of the string fields may be NULL, meaning you want to take anything in
that field. So if all the strings are NULL and the interface is -1 and the ipdomain is
GENSIO_NETTYPE_UNSPEC you will get all of the fields.

STRING VALUES FOR WATCHES

       The  string  values  to the watch add function may use regular expressions.  If the string
       starts with '%', then the data after it is treated as a regular expression and fields  are
       matched against that.  See the regex(7) man page for details.

       Globs  are  supported  on some platforms, but their use is discouraged because they aren't
       available on some platforms.  If the string starts with '@', the  the  data  after  it  is
       treated  as  a  standard  glob.   See  the glob(7) man page for details.  An error will be
       returned if the platform doesn't have glob matching.

       If the string starts with '=', an exact comparison is done with the data after it.

       If the string starts with a-z0-9_ or a space, then an exact  string  comparison  is  done,
       including the first character.

       The  behavior  of matching for any other starting character is undefined.  In general, you
       should always use '@', '%', or '=' as the starting character of all your query strings  to
       be sure.

RETURN VALUES

       Zero is returned on success, or a gensio error on failure.

NAME

SYNOPSIS

DESCRIPTION

STRING VALUES FOR WATCHES

RETURN VALUES

SEE ALSO