GROUP_SOURCE_REQ structure (ws2ipdef.h)

The GROUP_SOURCE_REQ structure provides multicast group information for IPv6 or IPv4 addresses that includes the source IP address.

Syntax

typedef struct group_source_req {
  ULONG            gsr_interface;
  SOCKADDR_STORAGE gsr_group;
  SOCKADDR_STORAGE gsr_source;
} GROUP_SOURCE_REQ, *PGROUP_SOURCE_REQ;

Members

gsr_interface

The interface index of the local interface on which the multicast group should be joined, dropped, blocked, or unblocked.

gsr_group

The address of the multicast group. This may be either an IPv6 or IPv4 multicast address.

gsr_source

The source address that should be used. This may be either an IPv6 or IPv4 multicast address, but it must be the same address family (IPv6 or IPv4) as the address specified in the gsr_group member.

Remarks

The GROUP_SOURCE_REQ structure is used with either IPv6 or IPv4 multicast addresses. The GROUP_SOURCE_REQ structure is used with the MCAST_BLOCK_SOURCE, MCAST_JOIN_SOURCE_GROUP, MCAST_LEAVE_SOURCE_GROUP, and MCAST_UNBLOCK_SOURCE socket options.

The GROUP_SOURCE_REQ structure and related structures used for multicast programming are based on IETF recommendations in sections 5 and 8.2 of RFC 3768. For more information, see http://www.ietf.org/rfc/rfc3678.txt.

On Windows Vista and later, a set of socket options are available for multicast programming that support IPv6 and IPv4 addresses. These socket options are IP agnostic and can be used on both IPv6 and IPv4. These IP agnostic options use the GROUP_REQ and the GROUP_SOURCE_REQ structures and are the preferred socket options for multicast programming on Windows Vista and later.

The GetAdaptersAddresses function can be used to obtain interface index information required for the gsr_interface member.

The GROUP_SOURCE_REQ structure and the socket options that use this structure are only valid on datagram and raw sockets (the socket type must be SOCK_DGRAM or SOCK_RAW).

The GROUP_SOURCE_REQ structure is defined in the Ws2ipdef.h header file which is automatically included in the Ws2tcpip.h header file. The Ws2ipdef.h header files should never be used directly.

Requirements

Requirement	Value
Minimum supported client	None supported
Minimum supported server	Windows Server 2008 [desktop apps only]
Header	ws2ipdef.h (include Ws2tcpip.h)

See also

GROUP_FILTER

GROUP_REQ

GetAdaptersAddresses

Multicast Programming

SOCKADDR_STORAGE

Socket Options

ip_mreq

ipv6_mreq