From b69e09ecd2ab5803178ce84efb020181bb81bd21 Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@collectd.org>
Date: Wed, 25 Sep 2013 11:53:11 +0200
Subject: [PATCH] libcollectdclient: Implement the lcc_server_set_interface()
 function.

Copied from the network plugin. License changed to MIT with permission
from Max Henkel, thank you very much!
---
 src/libcollectdclient/collectd/network.h |  1 +
 src/libcollectdclient/network.c          | 85 +++++++++++++++++++++++++++++++-
 2 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/src/libcollectdclient/collectd/network.h b/src/libcollectdclient/collectd/network.h
index 39626667..049f7f02 100644
--- a/src/libcollectdclient/collectd/network.h
+++ b/src/libcollectdclient/collectd/network.h
@@ -65,6 +65,7 @@ int lcc_server_destroy (lcc_network_t *net, lcc_server_t *srv);
 
 /* Configure servers */
 int lcc_server_set_ttl (lcc_server_t *srv, uint8_t ttl);
+int lcc_server_set_interface (lcc_server_t *srv, char const *interface);
 int lcc_server_set_security_level (lcc_server_t *srv,
     lcc_security_level_t level,
     const char *username, const char *password);
diff --git a/src/libcollectdclient/network.c b/src/libcollectdclient/network.c
index 6b6450c9..ddb3b5b9 100644
--- a/src/libcollectdclient/network.c
+++ b/src/libcollectdclient/network.c
@@ -1,6 +1,7 @@
 /**
  * collectd - src/libcollectdclient/network.c
- * Copyright (C) 2005-2012  Florian octo Forster
+ * Copyright (C) 2005-2013  Florian Forster
+ * Copyright (C) 2010       Max Henkel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -21,7 +22,8 @@
  * DEALINGS IN THE SOFTWARE.
  *
  * Authors:
- *   Florian octo Forster <octo at collectd.org>
+ *   Florian Forster <octo at collectd.org>
+ *   Max Henkel <henkel at gmx.at>
  **/
 
 #include "collectd.h"
@@ -41,6 +43,10 @@
 # include <netinet/in.h>
 #endif
 
+#if HAVE_NET_IF_H
+# include <net/if.h>
+#endif
+
 #include "collectd/network.h"
 #include "collectd/network_buffer.h"
 
@@ -379,6 +385,81 @@ int lcc_server_set_ttl (lcc_server_t *srv, uint8_t ttl) /* {{{ */
   return (0);
 } /* }}} int lcc_server_set_ttl */
 
+int lcc_server_set_interface (lcc_server_t *srv, char const *interface) /* {{{ */
+{
+  int if_index;
+  int status;
+
+  if ((srv == NULL) || (interface == NULL))
+    return (EINVAL);
+
+  if_index = if_nametoindex (interface);
+  if (if_index == 0)
+    return (ENOENT);
+
+  /* IPv4 multicast */
+  if (srv->sa->sa_family == AF_INET)
+  {
+    struct sockaddr_in *addr = (struct sockaddr_in *) srv->sa;
+
+    if (IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
+    {
+#if HAVE_STRUCT_IP_MREQN_IMR_IFINDEX
+      /* If possible, use the "ip_mreqn" structure which has
+       * an "interface index" member. Using the interface
+       * index is preferred here, because of its similarity
+       * to the way IPv6 handles this. Unfortunately, it
+       * appears not to be portable. */
+      struct ip_mreqn mreq;
+
+      memset (&mreq, 0, sizeof (mreq));
+      mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
+      mreq.imr_address.s_addr = ntohl (INADDR_ANY);
+      mreq.imr_ifindex = if_index;
+#else
+      struct ip_mreq mreq;
+
+      memset (&mreq, 0, sizeof (mreq));
+      mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
+      mreq.imr_interface.s_addr = ntohl (INADDR_ANY);
+#endif
+
+      status = setsockopt (srv->fd, IPPROTO_IP, IP_MULTICAST_IF,
+          &mreq, sizeof (mreq));
+      if (status != 0)
+        return (status);
+
+      return (0);
+    }
+  }
+
+  /* IPv6 multicast */
+  if (srv->sa->sa_family == AF_INET6)
+  {
+    struct sockaddr_in6 *addr = (struct sockaddr_in6 *) srv->sa;
+
+    if (IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
+    {
+      status = setsockopt (srv->fd, IPPROTO_IPV6, IPV6_MULTICAST_IF,
+          &if_index, sizeof (if_index));
+      if (status != 0)
+        return (status);
+
+      return (0);
+    }
+  }
+
+  /* else: Not a multicast interface. */
+#if defined(SO_BINDTODEVICE)
+  status = setsockopt (srv->fd, SOL_SOCKET, SO_BINDTODEVICE,
+      interface, strlen (interface) + 1);
+  if (status != 0)
+    return (-1);
+#endif
+
+  return (0);
+} /* }}} int lcc_server_set_interface */
+
 int lcc_server_set_security_level (lcc_server_t *srv, /* {{{ */
     lcc_security_level_t level,
     const char *username, const char *password)
-- 
2.11.0