[PATCH] ip.7: Adding source-specific multicast sockopts

[rpazdera-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org]

From: Radek Pazdera <rpazdera-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

This patch adds documentation of several source-specific multicast
socket options that were added to kernel with implementation
of IGMPv3 in 2.5.68.

The following socket options were added:
  IP_ADD_SOURCE_MEMBERSHIP
  IP_DROP_SOURCE_MEMBERSHIP
  IP_BLOCK_SOURCE
  IP_UNBLOCK_SOURCE
  IP_MSFILTER

Information Sources:
  * RFC 3376 - Internet Group Management Protocol, Version 3
      http://tools.ietf.org/html/rfc3376
  * RFC 3678 - Socket Interface Extensions for Multicast Source Filters
      http://tools.ietf.org/html/rfc3678
  * Kernel source tree
      net/ipv4/ip_sockglue.c
      net/ipv4/igmp.c
  * Test programs used in Linux Network Stack Test
      http://git.fedorahosted.org/git/?p=lnst.git
      test_tools/multicast/

Signed-off-by: Radek Pazdera <rpazdera-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 man7/ip.7 |  115 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)

diff --git a/man7/ip.7 b/man7/ip.7
index 9f560df..842dd3b 100644
--- a/man7/ip.7
+++ b/man7/ip.7
@@ -256,6 +256,58 @@ Only valid as a
 .BR setsockopt (2).
 .\"
 .TP
+.BR IP_ADD_SOURCE_MEMBERSHIP " (since Linux 2.5.68)"
+Join a multicast group and allow receiving data only
+from a specified source.
+Argument is an
+.I ip_mreq_source
+structure.
+.sp
+.in +4n
+.nf
+struct ip_mreq_source {
+    struct in_addr imr_multiaddr;  /* IP multicast group
+                                      address */
+    struct in_addr imr_interface;  /* IP address of local
+                                      interface */
+    struct in_addr imr_sourceaddr; /* IP address of
+                                      multicast source */
+};
+.fi
+.in
+.sp
+.I ip_mreq_source
+structure is similar to
+.I ip_mreqn
+described at
+.BR IP_ADD_MEMBERSIP .
+.I imr_multiaddr
+contains the address of the multicast group the application
+wants to join or leave.
+.I imr_interface
+is the address of the local interface with which
+the system should join the multicast group.
+Finally
+.I imr_sourceaddr
+field contains address of the source the
+application wants to receive data from.
+.IP
+This option can be used multiple times to allow
+receiving data from more than one source.
+.TP
+.BR IP_BLOCK_SOURCE " (since Linux 2.5.68)"
+Stop receiving multicast data from a specific source in a given
+group. This is valid only after the application has subscribed
+to the multicast group using either
+.BR IP_ADD_MEMBERSHIP
+or
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described at
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.TP
 .BR IP_DROP_MEMBERSHIP " (since Linux 1.2)"
 Leave a multicast group.
 Argument is an
@@ -265,6 +317,19 @@ or
 structure similar to
 .BR IP_ADD_MEMBERSHIP .
 .TP
+.BR IP_DROP_SOURCE_MEMBERSHIP " (since Linux 2.5.68)"
+Leave a source-specific group, i.e., stop receiving data from
+a given multicast group that come from a given source).
+If the application has subscribed to multiple sources within
+the same group, data from the remaining sources will still be
+delivered. To stop receiving data from all sources at once use
+.BR IP_LEAVE_GROUP .
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described at
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.TP
 .BR IP_FREEBIND " (since Linux 2.4)"
 .\" Precisely: 2.4.0-test10
 If enabled, this boolean option allows binding to an IP address
@@ -293,6 +358,45 @@ When this flag is enabled the values set by
 and
 .B IP_TOS
 are ignored.
+.TP
+.BR IP_MSFILTER " (since Linux 2.5.68)"
+This option provides access to the advanced full-state filtering API.
+Argument is an
+.I ip_msfilter
+structure.
+.sp
+.in +4n
+.nf
+struct ip_msfilter {
+    struct in_addr imsf_multiaddr; /* IP multicast group
+                                      address */
+    struct in_addr imsf_interface; /* IP address of local
+                                      interface */
+    uint32_t       imsf_fmode;     /* Filter-mode */
+
+    uint32_t       imsf_numsrc;    /* Number of sources in
+                                      the following array */
+    struct in_addr imsf_slist[1];  /* Array of source
+                                      addresses */
+};
+.fi
+.in
+.sp
+There are two macros,
+.BR MCAST_INCLUDE
+and
+.BR MCAST_EXCLUDE ,
+which can be used to specify the filtering mode.
+Additionaly,
+.BR IP_MSFILTER_SIZE (n)
+macro exists to determine how much memory is needed to store
+.I ip_msfilter
+structure with
+.I n
+sources in the source list.
+.IP
+For the full description of multicast source filtering
+refer to RFC 3376.
 .\"
 .\" FIXME Document IP_IPSEC_POLICY
 .\" Since Linux 2.5.47
@@ -768,6 +872,16 @@ this option be set on the redirected socket.
 .BR IP_TTL " (since Linux 1.0)"
 Set or retrieve the current time-to-live field that is used in every packet
 sent from this socket.
+.TP
+.BR IP_UNBLOCK_SOURCE " (since Linux 2.5.68)"
+Unblock previously blocked multicast source. Returns
+.BR EADDRNOTAVAIL
+when given source is not being blocked.
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described at
+.BR IP_ADD_SOURCE_MEMBERSHIP .
 .\" FIXME Document IP_XFRM_POLICY
 .\" Since Linux 2.5.48
 .\" Needs CAP_NET_ADMIN
@@ -1005,6 +1119,7 @@ and
 .BR socket (7).
 .SH NOTES
 .BR IP_FREEBIND ,
+.BR IP_MSFILTER ,
 .BR IP_MTU ,
 .BR IP_MTU_DISCOVER ,
 .BR IP_RECVORIGDSTADDR ,
-- 
1.7.10.4

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