getipv4sourcefilter function (ws2tcpip.h)

The getipv4sourcefilter inline function retrieves the multicast filter state for an IPv4 socket.

Syntax

int getipv4sourcefilter(
  [in]      SOCKET              Socket,
  [in]      IN_ADDR             Interface,
  [in]      IN_ADDR             Group,
  [out]     MULTICAST_MODE_TYPE *FilterMode,
  [in, out] ULONG               *SourceCount,
  [out]     IN_ADDR             *SourceList
);

Parameters

[in] Socket

A descriptor that identifies a multicast socket.

[in] Interface

The local IPv4 address of the interface or the interface index on which the multicast group should be joined or dropped.

This value is in network byte order. If this member specifies an IPv4 address of 0.0.0.0, the default IPv4 multicast interface is used.

Any IP address in the 0.x.x.x block (first octet of 0) except IPv4 address 0.0.0.0 is treated as an interface index. An interface index is a 24-bit number, and the 0.0.0.0/8 IPv4 address block is not used (this range is reserved).

To use an interface index of 1 would be the same as an IP address of 0.0.0.1.

[in] Group

The IPv4 address of the multicast group.

[out] FilterMode

A pointer to a value to receive the multicast filter mode for multicast group address when the function returns.

[in, out] SourceCount

On input, a pointer to a value that indicates the maximum number of source addresses that will fit in the buffer pointed to by the SourceList parameter.

On output, a pointer to a value that indicates the total number of source addresses associated with the multicast filter.

[out] SourceList

A pointer to a buffer to receive the list of IP addresses associated with the multicast filter.

If SourceCount is zero on input, a NULL pointer may be supplied.

Return value

On success, getipv4sourcefilter returns NO_ERROR (0). Any nonzero return value indicates failure and a specific error code can be retrieved by calling WSAGetLastError.

Remarks

The getipv4sourcefilter inline function is used to retrieve the multicast filter state for an IPv4 socket.

If the app does not know the size of the source list beforehand, it can make a guess (zero, for example). If upon completion, the SourceCount parameter holds a larger value, the operation can be repeated with a large enough buffer.

On return, the SourceCount parameter is always updated to be the total number of sources in the filter, while the buffer pointed to by the SourceList parameter will hold as many source addresses as fit, up to the minimum of the array size passed in as the original SourceCount value and the total number of sources in the filter.

This function is part of socket interface extensions for multicast source filters defined in RFC 3678. An app can use these functions to retrieve and set the multicast source address filters associated with a socket.

Windows Phone 8: This function is supported for Windows Phone Store apps on Windows Phone 8 and later.

Windows 8.1 and Windows Server 2012 R2: This function is supported for Windows Store apps on Windows 8.1, Windows Server 2012 R2, and later.

Requirements

See also

MULTICAST_MODE_TYPE

getsourcefilter

in_addr

setipv4sourcefilter

setsourcefilter