libbb: move netlink socket binding to the utility function

function                                             old     new   delta
create_and_bind_to_netlink                             -     134    +134
ifplugd_main                                        1117    1052     -65
uevent_main                                          399     306     -93
mdev_main                                            314     215     -99
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/3 up/down: 134/-257)         Total: -123 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index 39e56b223..ea5fe173f 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -11,6 +11,9 @@
 #include <netinet/in.h>
 #include <net/if.h>
 #include <sys/un.h>
+#if ENABLE_IFPLUGD || ENABLE_FEATURE_MDEV_DAEMON || ENABLE_UEVENT
+# include <linux/netlink.h>
+#endif
 #include "libbb.h"
 
 int FAST_FUNC setsockopt_int(int fd, int level, int optname, int optval)
@@ -412,6 +415,38 @@ int FAST_FUNC create_and_bind_dgram_or_die(const char *bindaddr, int port)
 }
 
 
+#if ENABLE_IFPLUGD || ENABLE_FEATURE_MDEV_DAEMON || ENABLE_UEVENT
+int FAST_FUNC create_and_bind_to_netlink(int proto, int grp, unsigned rcvbuf)
+{
+	struct sockaddr_nl sa;
+	int fd;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.nl_family = AF_NETLINK;
+	sa.nl_pid = getpid();
+	sa.nl_groups = grp;
+	fd = xsocket(AF_NETLINK, SOCK_DGRAM, proto);
+	xbind(fd, (struct sockaddr *) &sa, sizeof(sa));
+	close_on_exec_on(fd);
+
+	if (rcvbuf != 0) {
+		// SO_RCVBUFFORCE (root only) can go above net.core.rmem_max sysctl
+		setsockopt_SOL_SOCKET_int(fd, SO_RCVBUF,      rcvbuf);
+		setsockopt_SOL_SOCKET_int(fd, SO_RCVBUFFORCE, rcvbuf);
+# if 0
+		{
+			int z;
+			socklen_t zl = sizeof(z);
+			getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &z, &zl);
+			bb_error_msg("SO_RCVBUF:%d", z);
+		}
+# endif
+	}
+
+	return fd;
+}
+#endif
+
 int FAST_FUNC create_and_connect_stream_or_die(const char *peer, int port)
 {
 	int fd;