libbb: set netlink socket revbuf size before binding

As soon as the socket is bound it will receive messages. Make sure the
recieve buffer size is increased before the first message is received.

Signed-off-by: Jan Klötzke <jan@kloetzke.net>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index e9a2470e4..5dd9cfd28 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -422,17 +422,14 @@ 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);
 
+        /* Set receive buffer size before binding the socket
+         * We want to have enough space before we start receiving messages.
+         */
         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_RCVBUF, rcvbuf);
+                /* SO_RCVBUFFORCE (root only) can go above net.core.rmem_max */
                 setsockopt_SOL_SOCKET_int(fd, SO_RCVBUFFORCE, rcvbuf);
 # if 0
                 {
@@ -444,6 +441,13 @@ int FAST_FUNC create_and_bind_to_netlink(int proto, int grp, unsigned rcvbuf)
 # endif
         }
 
+        memset(&sa, 0, sizeof(sa));
+        sa.nl_family = AF_NETLINK;
+        sa.nl_pid = getpid();
+        sa.nl_groups = grp;
+        xbind(fd, (struct sockaddr *) &sa, sizeof(sa));
+        close_on_exec_on(fd);
+
         return fd;
 }
 #endif