igmp(7tcp)

igmp -- Internet Group Management Protocol

Synopsis

Programmer's interface:

#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
 
s = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP); 
 
#include <paths.h> 
#include <fcntl.h> 
#include <netinet/ip_var.h> 
#include <netinet/igmp_var.h> 
 
fd = open(_PATH_IGMP, flags);

Description

IGMP is used by Internet hosts and routers to keep track of multicast groups. It may be accessed through a ``raw socket'' for network monitoring and diagnostic functions. IGMP sockets are connectionless, and are normally used with the sendto and recvfrom calls; the connect(3sock) call may also be used to fix the destination for future packets (in which case the read(2) or recv(3sock) and write(2) or send(3sock) system calls may be used).

Outgoing packets automatically have an IPv4 header prepended to them (based on the destination address). Incoming packets are received with the IPv4 header and options intact.

The IGMP driver can also be accessed by opening it directly. Networking statistics can be gathered by issuing an ioctl directive to the driver.

The following STREAMS ioctl requests, defined in <netinet/ip_var.h>, and <netinet/igmp_var.h> are supported by the IGMP driver :

SIOCGIGMPSTATS: Fetch the IGMP statistics structure. The argument passed to the I_STR call is a pointer to an igmpstat structure.
SIOCSMGMT: To set the inpcb associated with that end-point as a management inpcb (to distinguish it from others, when network statistics are gathered).

Diagnostics

A socket operation may fail with one of the following errors returned:

[EADDRNOTAVAIL]: when an attempt is made to create a socket with a network address for which no network interface exists.
[EISCONN]: when trying to establish a connection on a socket which already has one, or when trying to send a datagram with the destination address specified and the socket is already connected.
[ENOTCONN]: when trying to send a datagram, but no destination address is specified, and the socket has not been connected.
[ENOMEM]: when the system runs out of memory for an internal data structure.
[ENOSR]: when the system runs out of STREAMS resources.

The errno is set to the following value upon the failure of the ioctl operation:

[EINVAL]: when an invalid argument is passed to the driver.

References

if(7tcp), inconfig(1Mtcp), inet(7tcp), ip(7tcp), recv(3sock), send(3sock), streamio(7)

``Internet Group Management Protocol Version 4 (IGMPv4) parameters'' on the inconfig(1Mtcp) manual page

RFC 1112