zebra: Allow *BSD to specify a receive buffer size

End operator is reporting that they are receiving buffer overruns
when attempting to read from the kernel receive socket.  It is
possible to adjust this size to more modern levels especially
for when the system is under load.  Modify the code base
so that *BSD operators can use the zebra `-s XXX` option
to specify a read buffer.

Additionally setup the default receive buffer size on *BSD
to be 128k instead of the 8k so that FRR does not run into
this issue again.

Fixes: #10666
Signed-off-by: Donald Sharp <sharpd@nvidia.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/zebra/kernel_socket.c b/zebra/kernel_socket.c
index 53b7a21d32..d812094848 100644
--- a/zebra/kernel_socket.c
+++ b/zebra/kernel_socket.c
@@ -1408,6 +1408,9 @@ static void kernel_read(struct thread *thread)
 /* Make routing socket. */
 static void routing_socket(struct zebra_ns *zns)
 {
+	uint32_t default_rcvbuf;
+	socklen_t optlen;
+
 	frr_with_privs(&zserv_privs) {
 		routing_sock = ns_socket(AF_ROUTE, SOCK_RAW, 0, zns->ns_id);
 
@@ -1442,6 +1445,23 @@ static void routing_socket(struct zebra_ns *zns)
 	/*if (fcntl (routing_sock, F_SETFL, O_NONBLOCK) < 0)
 	  zlog_warn ("Can't set O_NONBLOCK to routing socket");*/
 
+	/*
+	 * Attempt to set a more useful receive buffer size
+	 */
+	optlen = sizeof(default_rcvbuf);
+	if (getsockopt(routing_sock, SOL_SOCKET, SO_RCVBUF, &default_rcvbuf,
+		       &optlen) == -1)
+		flog_err_sys(EC_LIB_SOCKET,
+			     "routing_sock sockopt SOL_SOCKET SO_RCVBUF");
+	else {
+		for (; rcvbufsize > default_rcvbuf &&
+		       setsockopt(routing_sock, SOL_SOCKET, SO_RCVBUF,
+				  &rcvbufsize, sizeof(rcvbufsize)) == -1 &&
+		       errno == ENOBUFS;
+		     rcvbufsize /= 2)
+			;
+	}
+
 	/* kernel_read needs rewrite. */
 	thread_add_read(zrouter.master, kernel_read, NULL, routing_sock, NULL);
 }