network plugin: Bind to device for unicast

Hello list!

On Tue, Mar 09, 2010 at 06:17:35PM +0100, Florian Forster wrote:
[...]
> On Fri, Feb 26, 2010 at 12:49:02PM +0100, Max Henkel wrote:
[...]
> > +           if (! IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
> > +                   return (0);
>
> Doesn't it make sense to be able to set the interface in unicast mode,
> too? For example if the host has multiple default gateways. The
> socket(7) option "SO_BINDTODEVICE" could be used for this I guess.
[...]

Thus this patch binds the socket to a specific interface for unicast
traffic, too. But, as Sebastian already mentioned, the behaviour is
Linux specific.

Best regards,

Max

Signed-off-by: Florian Forster <octo@huhu.verplant.org>

diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index c490a2e..e2306d2 100644 (file)
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -2571,10 +2571,12 @@ operating systems.
 
 =item B<Interface> I<Interface name>
 
-Set the outgoing or incoming interface for multicast packets. This applies
-at least to IPv6 packets and if possible to IPv4. If it is not applicable or
-defined the default behaviour is to let the kernel choose the appropriate
-interface.
+Set the outgoing or incoming interface for IP packets. This applies at least
+to IPv6 packets and if possible to IPv4. If this option is not applicable,
+undefined or a non-existent interface name is specified, the default
+behaviour is to let the kernel choose the appropriate interface. Be warned
+that the manual selection of an interface for unicast traffic is only
+necessary in rare cases.
 
 =item B<MaxPacketSize> I<1024-65535>
 

diff --git a/src/network.c b/src/network.c
index b6e21b9..eb074e9 100644 (file)
--- a/src/network.c
+++ b/src/network.c
@@ -1597,50 +1597,77 @@ static int network_set_interface (const sockent_t *se, const struct addrinfo *ai
        if (ai->ai_family == AF_INET)
        {
                struct sockaddr_in *addr = (struct sockaddr_in *) ai->ai_addr;
+
+               if (IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
+               {
 #if KERNEL_LINUX
-               struct ip_mreqn mreq;
+                       struct ip_mreqn mreq;
 #else
-               struct ip_mreq mreq;
+                       struct ip_mreq mreq;
 #endif
 
-               if (! IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
-                       return (0);
-
-               mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
+                       mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
 #if KERNEL_LINUX
-               mreq.imr_address.s_addr = ntohl (INADDR_ANY);
-               mreq.imr_ifindex = network_config_interface_idx;
+                       mreq.imr_address.s_addr = ntohl (INADDR_ANY);
+                       mreq.imr_ifindex = network_config_interface_idx;
 #else
-               mreq.imr_interface.s_addr = ntohl (INADDR_ANY);
+                       mreq.imr_interface.s_addr = ntohl (INADDR_ANY);
 #endif
 
-               if (setsockopt (se->data.client.fd, IPPROTO_IP, IP_MULTICAST_IF,
-                                       &mreq, sizeof (mreq)) == -1)
-               {
-                       char errbuf[1024];
-                       ERROR ("setsockopt: %s",
-                                       sstrerror (errno, errbuf, sizeof (errbuf)));
-                       return (-1);
+                       if (setsockopt (se->data.client.fd, IPPROTO_IP, IP_MULTICAST_IF,
+                                               &mreq, sizeof (mreq)) == -1)
+                       {
+                               char errbuf[1024];
+                               ERROR ("setsockopt: %s",
+                                               sstrerror (errno, errbuf, sizeof (errbuf)));
+                               return (-1);
+                       }
+
+                       return (0);
                }
        }
        else if (ai->ai_family == AF_INET6)
        {
                struct sockaddr_in6 *addr = (struct sockaddr_in6 *) ai->ai_addr;
 
-               if (! IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
+               if (IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
+               {
+                       if (setsockopt (se->data.client.fd, IPPROTO_IPV6, IPV6_MULTICAST_IF,
+                                               &network_config_interface_idx,
+                                               sizeof (network_config_interface_idx)) == -1)
+                       {
+                               char errbuf[1024];
+                               ERROR ("setsockopt: %s",
+                                               sstrerror (errno, errbuf,
+                                                       sizeof (errbuf)));
+                               return (-1);
+                       }
+
                        return (0);
+               }
+       }
+
+#if KERNEL_LINUX
+       if (network_config_interface_idx != 0)
+       {
+               char interface_name[IFNAMSIZ];
+
+               if (if_indextoname (network_config_interface_idx, interface_name) == NULL)
+                       return (-1);
 
-               if (setsockopt (se->data.client.fd, IPPROTO_IPV6, IPV6_MULTICAST_IF,
-                                       &network_config_interface_idx,
-                                       sizeof (network_config_interface_idx)) == -1)
+               DEBUG ("network plugin: Binding socket to interface %s", interface_name);
+
+               if (setsockopt (se->data.client.fd, SOL_SOCKET, SO_BINDTODEVICE,
+                                       interface_name,
+                                       sizeof(interface_name)) == -1 )
                {
                        char errbuf[1024];
                        ERROR ("setsockopt: %s",
-                                       sstrerror (errno, errbuf,
-                                               sizeof (errbuf)));
+                                       sstrerror (errno, errbuf, sizeof (errbuf)));
                        return (-1);
                }
        }
+#endif
 
        return (0);
 } /* }}} network_set_interface */
@@ -1709,6 +1736,8 @@ static int network_bind_socket (int fd, const struct addrinfo *ai)
                                                        sizeof (errbuf)));
                                return (-1);
                        }
+
+                       return (0);
                }
        }
        else if (ai->ai_family == AF_INET6)
@@ -1755,8 +1784,35 @@ static int network_bind_socket (int fd, const struct addrinfo *ai)
                                                        sizeof (errbuf)));
                                return (-1);
                        }
+
+                       return (0);
+               }
+       }
+
+#if KERNEL_LINUX
+       /* if a specific interface was set, bind the socket to it. But to avoid
+        * possible problems with multicast routing, only do that for non-multicast
+        * addresses */
+       if (network_config_interface_idx != 0)
+       {
+               char interface_name[IFNAMSIZ];
+
+               if (if_indextoname (network_config_interface_idx, interface_name) == NULL)
+                       return (-1);
+
+               DEBUG ("fd = %i; Binding socket to interface %s", fd, interface_name);
+
+               if (setsockopt (fd, SOL_SOCKET, SO_BINDTODEVICE,
+                                       interface_name,
+                                       sizeof(interface_name)) == -1 )
+               {
+                       char errbuf[1024];
+                       ERROR ("setsockopt: %s",
+                                       sstrerror (errno, errbuf, sizeof (errbuf)));
+                       return (-1);
                }
        }
+#endif
 
        return (0);
 } /* int network_bind_socket */