Ros interface to linux's avahi daemon. More...

#include <zeroconf.hpp>

Public Member Functions
bool	add_listener (std::string &service_type)
bool	add_service (PublishedService &service)
void	connect_signal_callbacks (connection_signal_cb new_connections, connection_signal_cb lost_connections)
void	list_discovered_services (const std::string &service_type, std::vector< zeroconf_msgs::DiscoveredService > &list)
void	list_published_services (const std::string &service_type, std::vector< zeroconf_msgs::PublishedService > &list)
bool	remove_listener (const std::string &service_type)
bool	remove_service (const PublishedService &service)
void	spin ()
	Zeroconf ()
	~Zeroconf ()
Private Types
typedef boost::function< void(zeroconf_msgs::DiscoveredService)>	connection_signal_cb
typedef std::set < boost::shared_ptr < DiscoveredAvahiService > , DiscoveredAvahiServiceCompare >	discovered_service_set
typedef boost::bimaps::bimap < AvahiServiceBrowser *, boost::bimaps::set_of < std::string > >	discovery_bimap
typedef zeroconf_msgs::PublishedService	PublishedService
typedef boost::bimaps::bimap < AvahiEntryGroup *, boost::bimaps::set_of < PublishedService, PublishedServiceCompare > >	service_bimap
typedef std::pair < AvahiEntryGroup *, PublishedService >	service_map_pair
Private Member Functions
bool	add_service_non_threaded (PublishedService &service)
int	avahi_to_ros_protocol (const int &protocol)
std::string	avahi_to_txt_protocol (const int &protocol)
void	fail ()
discovered_service_set::iterator	find_discovered_service (zeroconf_msgs::DiscoveredService &service)
int	ros_to_avahi_protocol (const int &protocol)
std::string	ros_to_txt_protocol (const int &protocol)
Static Private Member Functions
static void	client_callback (AvahiClient c, AvahiClientState state, void userdata)
static void	discovery_callback (AvahiServiceBrowser b, AvahiIfIndex interface, AvahiProtocol protocol, AvahiBrowserEvent event, const char name, const char type, const char domain, AvahiLookupResultFlags flags, void *userdata)
static void	entry_group_callback (AvahiEntryGroup g, AvahiEntryGroupState state, void userdata)
static void	modify_callback (AVAHI_GCC_UNUSED AvahiTimeout e, void userdata)
static void	resolve_callback (AvahiServiceResolver r, AvahiIfIndex interface, AvahiProtocol protocol, AvahiResolverEvent event, const char name, const char type, const char domain, const char host_name, const AvahiAddress address, uint16_t port, AvahiStringList txt, AvahiLookupResultFlags flags, void userdata)
Private Attributes
AvahiClient *	client
service_bimap	committed_services
discovered_service_set	discovered_services
discovery_bimap	discovery_service_types
service_bimap	established_services
const int	interface
bool	invalid_object
connection_signal_cb	lost_connection_signal
connection_signal_cb	new_connection_signal
const int	permitted_protocols
boost::mutex	service_mutex
AvahiThreadedPoll *	threaded_poll

Detailed Description

Ros interface to linux's avahi daemon.

Avahi code is difficult to use (alot of black magic), so this class provides a convenient c++ interface to the avahi daemon that supplies the required api useful for a ros node (separate to this class).

Constraints:

It can easily be made purely c++ by substituting ros comms with pure c++ structs and doing conversions in the ros node (possibly a future job if necessary).

Currently defaulting to ipv4 addresses only. Just hardcode the library to use AVAHI_PROTO_UNSPEC if we ever want to move to using ipv6 as well (probably need some extra logic here and there as well).

Definition at line 162 of file zeroconf.hpp.

Member Typedef Documentation

typedef boost::function<void(zeroconf_msgs::DiscoveredService)> zeroconf_avahi::Zeroconf::connection_signal_cb [private]

Definition at line 170 of file zeroconf.hpp.

typedef std::set<boost::shared_ptr<DiscoveredAvahiService>, DiscoveredAvahiServiceCompare> zeroconf_avahi::Zeroconf::discovered_service_set [private]

Definition at line 168 of file zeroconf.hpp.

typedef boost::bimaps::bimap<AvahiServiceBrowser*, boost::bimaps::set_of<std::string> > zeroconf_avahi::Zeroconf::discovery_bimap [private]

Definition at line 167 of file zeroconf.hpp.

typedef zeroconf_msgs::PublishedService zeroconf_avahi::Zeroconf::PublishedService [private]

Definition at line 165 of file zeroconf.hpp.

typedef boost::bimaps::bimap<AvahiEntryGroup*, boost::bimaps::set_of<PublishedService, PublishedServiceCompare> > zeroconf_avahi::Zeroconf::service_bimap [private]

Definition at line 166 of file zeroconf.hpp.

typedef std::pair<AvahiEntryGroup*, PublishedService> zeroconf_avahi::Zeroconf::service_map_pair [private]

Definition at line 169 of file zeroconf.hpp.

Constructor & Destructor Documentation

zeroconf_avahi::Zeroconf::Zeroconf ( )

Definition at line 37 of file lib/zeroconf.cpp.

zeroconf_avahi::Zeroconf::~Zeroconf ( )

Definition at line 67 of file lib/zeroconf.cpp.

Member Function Documentation

bool zeroconf_avahi::Zeroconf::add_listener ( std::string & service_type )

Definition at line 114 of file lib/zeroconf.cpp.

bool zeroconf_avahi::Zeroconf::add_service ( PublishedService & service )

Add a service.

This goes through the threaded poll, so services can be added in runtime (i.e. after initial configuration).

We also keep a copy of the service to be added, so we can track through to the entry_group_callback, exactly which service is getting added.

Note that the service is not const - see add_service_non_threaded for more details.

Definition at line 206 of file lib/zeroconf.cpp.

bool zeroconf_avahi::Zeroconf::add_service_non_threaded ( PublishedService & service ) [private]

Non threaded add service - only for internal use because we need to be thread-safe.

Note that the service is not const - we will rename the service if it suffers from a local name collision. This is just a convenience and doesn't help the case when it is renamed in non-local collisions.

Definition at line 223 of file lib/zeroconf.cpp.

int zeroconf_avahi::Zeroconf::avahi_to_ros_protocol ( const int & protocol ) [private]

Definition at line 451 of file lib/zeroconf.cpp.

std::string zeroconf_avahi::Zeroconf::avahi_to_txt_protocol ( const int & protocol ) [private]

Definition at line 472 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::client_callback	(	AvahiClient *	c,
		AvahiClientState	state,
		void *	userdata
	)		`[static, private]`

Used to update client connection with the avahi daemon. This gets called in Zeroconf's construction where it checks to see that the avahi-daemon is actually up and running.

Parameters:

c	: client that is connecting.
state	: updated state for the client-daemon connection.
userdata	: this will always be the Zeroconf class.

Definition at line 976 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::connect_signal_callbacks	(	connection_signal_cb	new_connections,
		connection_signal_cb	lost_connections
	)		`[inline]`

Definition at line 186 of file zeroconf.hpp.

void zeroconf_avahi::Zeroconf::discovery_callback	(	AvahiServiceBrowser *	browser,
		AvahiIfIndex	interface,
		AvahiProtocol	protocol,
		AvahiBrowserEvent	event,
		const char *	name,
		const char *	type,
		const char *	domain,
		AvahiLookupResultFlags	flags,
		void *	userdata
	)		`[static, private]`

Called whenever a service that is being listened to is added or removed. If you've got no listeners, this doesn't get called.

Parameters:

browser
interface
protocol
event
name
type
domain
flags
userdata

Definition at line 536 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::entry_group_callback	(	AvahiEntryGroup *	g,
		AvahiEntryGroupState	state,
		void *	userdata
	)		`[static, private]`

Called whenever the the state of the entry group changes (or in english, whenever something noteworthy has happened to advertisements).

Not sure exactly, but after some testing, it seems that this also locks the threaded poll mutex for certain state changes, most notably, 'registering' and 'established'.

Making a big assumption here, but assuming that the callbacks will get processed for registering services in the order that they were committed. If this is true, we just look up the first service in the committed_services variable to see which service we're handling.

Definition at line 861 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::fail ( ) [inline, private]

Definition at line 220 of file zeroconf.hpp.

Zeroconf::discovered_service_set::iterator zeroconf_avahi::Zeroconf::find_discovered_service ( zeroconf_msgs::DiscoveredService & service ) [private]

Internal routine to quickly find a discovered service.

If calling from another thread, make sure its protected by service_mutex.

Parameters:

service : minimally defined service by name, type, domain, interface, protocol

Returns:: iterator : points to the found object or discovered_services.end() if none found.

Definition at line 501 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::list_discovered_services	(	const std::string &	service_type,
		std::vector< zeroconf_msgs::DiscoveredService > &	list
	)

Retrieves all the currently discovered services, or just those of those of the specified type that have been discovered. It goes the extra yard as well, just to make sure those services are resolvable (i.e. haven't dropped out or gone out of wireless range) which is important for robotics.

Parameters:

service_type	: service type specification
list	: list of services that have been discovered (return value)

Definition at line 348 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::list_published_services	(	const std::string &	service_type,
		std::vector< zeroconf_msgs::PublishedService > &	list
	)

Definition at line 379 of file lib/zeroconf.cpp.

static void zeroconf_avahi::Zeroconf::modify_callback	(	AVAHI_GCC_UNUSED AvahiTimeout *	e,
		void *	userdata
	)		`[static, private]`

bool zeroconf_avahi::Zeroconf::remove_listener ( const std::string & service_type )

Definition at line 148 of file lib/zeroconf.cpp.

bool zeroconf_avahi::Zeroconf::remove_service ( const PublishedService & service )

Definition at line 310 of file lib/zeroconf.cpp.

void zeroconf_avahi::Zeroconf::resolve_callback	(	AvahiServiceResolver *	resolver,
		AvahiIfIndex	interface,
		AvahiProtocol	protocol,
		AvahiResolverEvent	event,
		const char *	name,
		const char *	type,
		const char *	domain,
		const char *	host_name,
		const AvahiAddress *	address,
		uint16_t	port,
		AvahiStringList *	txt,
		AvahiLookupResultFlags	flags,
		void *	userdata
	)		`[static, private]`

This gets called by a resolver (created by avahi_resolver_new) whenever a discovered service goes up and down. Note that this only works if you keep the resolver open (do not free it!).

There are a couple of avahi bugs in here I think. Workarounds:

1) Sometimes when a serivce times out and the same service (name, type, domain, interface and protocol) is started on another address, it will trigger this callback before actually setting the address value. If you let it sleep for a bit, it will catch the correct address. Doing that here, but it really shouldn't call the callback until this is set internally by avahi.

2) It will sometimes RESOLVER_FOUND with an ipv6 address for an ipv4 service. This seems to happen immediately before a service times out. We check for this here and ignore it if this is the case.

Parameters: