A datagram socket to be used for multicasts. More...

#include <Socket.h>

Inheritance diagram for nidas::util::MulticastSocket:

Public Member Functions
	MulticastSocket ()
	Create an unbound multicast socket.

	MulticastSocket (int port)
	Create multicast socket, bind it to a local port.

	MulticastSocket (const Inet4SocketAddress &addr)
	Creates a datagram socket and binds it to the specified local address.

void	joinGroup (Inet4Address groupAddr)
	Join a multicast group on all interfaces.

void	joinGroup (Inet4Address groupAddr, const Inet4NetworkInterface &iface)
	Join a multicast group on a given interface.

void	leaveGroup (Inet4Address groupAddr)
	Leave a multicast group on all interfaces.

void	leaveGroup (Inet4Address groupAddr, const Inet4NetworkInterface &iface)
	Leave a multicast group on a given interface.

void	setTimeToLive (int val)

int	getTimeToLive () const

void	setMulticastLoop (bool val)
	Whether to set the IP_MULTICAST_LOOP socket option.

bool	getMulticastLoop () const

void	setInterface (Inet4Address maddr, const Inet4NetworkInterface &iface)
	Set the interface for a given multicast address.

void	setInterface (Inet4Address iaddr)
	Set the interface for a given multicast address.

Inet4NetworkInterface	getInterface () const

Inet4NetworkInterface	findInterface (const Inet4Address &iaddr) const

std::list< Inet4NetworkInterface >	getInterfaces () const
	Return the IP addresses of all my network interfaces.

void	close ()

void	setTimeout (int val)
	Set the timeout for receive(), recv(), and recvfrom() methods.

void	connect (const std::string &host, int port)
	Datagrams are connectionless, so this doesn't establish a true connection, it just sets the default destination address for the send() calls.

void	connect (const Inet4Address &addr, int port)
	Datagrams are connectionless, so this doesn't establish a true connection, it just sets the default destination address for the send() calls.

void	connect (const SocketAddress &addr)
	Datagrams are connectionless, so this doesn't establish a true connection, it just sets the default destination address for the send() calls.

void	bind (const Inet4Address &addr, int port)
	Bind the DatagramSocket to the specified local address.

void	bind (const SocketAddress &addr)
	Bind the DatagramSocket to the specified local address.

int	getFd () const

void	receive (DatagramPacketBase &packet)
	Read a packet from the DatagramSocket.

void	receive (DatagramPacketBase &packet, Inet4PacketInfo &info, int flags=0)
	Read a packet from the DatagramSocket.

void	send (const DatagramPacketBase &packet, int flags=0)

size_t	send (const void *buf, size_t len, int flags=0)

size_t	send (const struct iovec *iov, int iovcnt, int flags=MSG_NOSIGNAL)

size_t	recv (void *buf, size_t len, int flags=0)

size_t	recvfrom (void *buf, size_t len, int flags, SocketAddress &from)

size_t	sendto (const void *buf, size_t len, int flags, const SocketAddress &to)

size_t	sendto (const struct iovec *iov, int iovcnt, int flags, const SocketAddress &to)

const SocketAddress &	getLocalSocketAddress () const
	Get local address of this socket.

int	getLocalPort () const
	Get local port number of this socket.

void	setNonBlocking (bool val)
	Do fcntl system call to set O_NONBLOCK file descriptor flag on the socket.

bool	isNonBlocking () const

void	setReceiveBufferSize (int size)

int	getReceiveBufferSize ()

void	setSendBufferSize (int size)

int	getSendBufferSize ()

void	setBroadcastEnable (bool val)

bool	getBroadcastEnable () const

void	setPktInfo (bool val)
	Control whether a IP_PKTINFO ancillary message is received with each datagram.

Protected Attributes
SocketImpl	_impl

Detailed Description

A datagram socket to be used for multicasts.

This class provides the default public copy constructors and assignment operators. Objects of this class can be copied and assigned to without restriction. However, because of this, the destructor does not close the socket, so, in general, you should make sure that the socket is closed once at some point.

Usage example:

// host A listens for multicasts to address 239.0.0.1, port 9000:
MulticastSocket msock(9000);
// join the multicast group in whatever interface the system chooses,
// typically the first ethernet interface.
msock.joinGroup(Inet4Address::getByName("239.0.0.1"));
char buf[512];
Inet4SocketAddress from;
for (;;) {
    msock.recvfrom(buf,sizeof(buf),0,from);
    ...
}
 
// how to join on all multicast and loopback interfaces
// note that multicast works over the loopback interface
list<Inet4NetworkInterface> ifaces = msock.getInterfaces();
for (list<Inet4NetworkInterface>::const_iterator ii = ifaces.begin();
      ii != ifaces.end(); ++ii)
{
      if ((ii->getFlags() & (IFF_LOOPBACK | IFF_MULTICAST)) && (ii->getFlags() & IFF_UP))
          msock.joinGroup(Inet4Address::getByName("239.0.0.1"),*ii);
}
 
 
// host B multicasts to address 239.0.0.1, port 9000:
DatagramSocket msock;
Inet4Address maddr = Inet4Address::getByName("239.0.0.1");
Inet4SocketAddress msaddr = Inet4SocketAddress(maddr,9000);
for (;;) {
    msock.sendto("hello\n",6,0,msaddr);
    ...
}
 
// host C also does similar multicasts, but uses MulticastSocket
// methods to send packets out a specific interface, and
// to set the time to live (TTL) parameter.
MulticastSocket msock;
Inet4Address maddr = Inet4Address::getByName("239.0.0.1");
list<Inet4NetworkInterfaces> ifaces = msock.getInterfaces();
list<Inet4NetworkInterfaces>::const_iterator ii; 
for (ii = ifaces.begin(); ii != ifaces.end(); ++ii) {
  Inet4NetworkInterface ni = *ii;
  if (ni.getName() == "eth1")
      msock.setInterface(maddr,ni);
}
msock.setTimeToLive(2);  // go through one router
Inet4SocketAddress msaddr = Inet4SocketAddress(maddr,9000);
for (;;) {
    msock.sendto("hello\n",6,0,msaddr);
    ...
}

Note: if the above examples are not working for you, check your firewall settings. They might be blocking multicasts.

Constructor & Destructor Documentation

◆ MulticastSocket() [1/3]

nidas::util::MulticastSocket::MulticastSocket ( )

inline

Create an unbound multicast socket.

You must bind it to a port if you want to receive packets. If you are sending packets on this MulticastSocket, and do not use getInterfaces() and setInterface() to choose a specific interface, the system sends packets out on the first non-loopback interface that it finds. If a firewall is blocking multicast packets on that interface the packets won't be sent.

Exceptions

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ MulticastSocket() [1/3]

◆ MulticastSocket() [2/3]

◆ MulticastSocket() [3/3]

Member Function Documentation

◆ bind() [1/2]

◆ bind() [2/2]

◆ close()

◆ connect() [1/3]

◆ connect() [2/3]

◆ connect() [3/3]

◆ findInterface()

◆ getBroadcastEnable()

◆ getFd()

◆ getInterface()

◆ getInterfaces()

◆ getLocalPort()

◆ getLocalSocketAddress()

◆ getMulticastLoop()

◆ getReceiveBufferSize()

◆ getSendBufferSize()

◆ getTimeToLive()

◆ isNonBlocking()

◆ joinGroup() [1/2]

◆ joinGroup() [2/2]

◆ leaveGroup() [1/2]

◆ leaveGroup() [2/2]

◆ receive() [1/2]

◆ receive() [2/2]

◆ recv()

◆ recvfrom()

◆ send() [1/3]

◆ send() [2/3]

◆ send() [3/3]

◆ sendto() [1/2]

◆ sendto() [2/2]

◆ setBroadcastEnable()

◆ setInterface() [1/2]

◆ setInterface() [2/2]

◆ setMulticastLoop()

◆ setNonBlocking()

◆ setPktInfo()

◆ setReceiveBufferSize()

◆ setSendBufferSize()

◆ setTimeout()

◆ setTimeToLive()

Member Data Documentation

◆ _impl