netlink: automatically increase netlink receive buffer on errors

diff --git a/configure.ac b/configure.ac
index af48ed6e60b2aaa84a33675719edae507e00f3f3..b871f94b092ebe33264e48af3a742419074bc607 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -348,7 +348,8 @@ lldp_ARG_WITH([lldpd-ctl-socket], [Path to socket for communication with lldpd],
 lldp_ARG_WITH([lldpd-pid-file], [Path to lldpd PID file], [${runstatedir}/lldpd.pid])
 
 # Netlink
-lldp_ARG_WITH_UNQUOTED([netlink-receive-bufsize], [Netlink receive buffer size], [256*1024])
+lldp_ARG_WITH_UNQUOTED([netlink-max-receive-bufsize], [Netlink maximum receive buffer size], [4*1024*1024])
+lldp_ARG_WITH_UNQUOTED([netlink-receive-bufsize], [Netlink initial receive buffer size], [256*1024])
 lldp_ARG_WITH_UNQUOTED([netlink-send-bufsize], [Netlink send buffer size], [0])
 
 # CDP/FDP/EDP/SONMP

diff --git a/src/daemon/netlink.c b/src/daemon/netlink.c
index cc1def0001bc879c70960f70027846597a8651f3..7d7814e6a4f408bbff506f3754b13064fdaabe59 100644 (file)
--- a/src/daemon/netlink.c
+++ b/src/daemon/netlink.c
@@ -35,6 +35,7 @@ struct netlink_req {
 
 struct lldpd_netlink {
        int nl_socket;
+       int can_increase;       /* Can we increase the netlink socket size? */
        /* Cache */
        struct interfaces_device_list *devices;
        struct interfaces_address_list *addresses;
@@ -85,6 +86,44 @@ netlink_socket_set_buffer_sizes(int s, int sndbuf, int rcvbuf)
        return 0;
 }
 
+/**
+ * Double the size of the receive netlink send buffer.
+ *
+ * Returns 0 on success, -1 on system error, 1 when we were unable to grow the
+ * buffer more.
+ */
+static int
+netlink_socket_double_buffer_sizes(int s, int max)
+{
+       socklen_t size = sizeof(int);
+       int current = 0, got = 0;
+       if (getsockopt(s, SOL_SOCKET, SO_RCVBUF, &current, &size) < 0) {
+               log_warn("netlink", "unable to get SO_RCVBUF");
+               return -1;
+       }
+       if (current < max) {
+               current *= 2;
+               if (current > max)
+                       current = max;
+               if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &current, sizeof(current)) < 0) {
+                       log_warn("netlink", "unable to set SO_RCVBUF to '%d'", current);
+                       return -1;
+               }
+               if (getsockopt(s, SOL_SOCKET, SO_RCVBUF, &got, &size) < 0) {
+                       log_warn("netlink", "unable to get SO_RCVBUF");
+                       return -1;
+               }
+               if (got != current) {
+                       log_warn("netlink", "tried to set SO_RCVBUF to '%d' "
+                           "but got '%d'", current, got);
+                       return 1; /* Assume we got the maximum */
+               }
+               log_debug("netlink", "increased SO_RCVBUF to %d", current);
+               return 0;
+       }
+       return 1;               /* Maximum alredy reached */
+}
+
 /**
  * Connect to netlink.
  *
@@ -417,7 +456,8 @@ netlink_merge(struct interfaces_device *old, struct interfaces_device *new)
 static int
 netlink_recv(int s,
     struct interfaces_device_list *ifs,
-    struct interfaces_address_list *ifas)
+    struct interfaces_address_list *ifas,
+    int *can_increase)
 {
        int end = 0, ret = 0;
        int flags = MSG_PEEK | MSG_TRUNC;
@@ -456,6 +496,19 @@ retry:
                                ret = 0;
                                goto out;
                        }
+                       if (errno == ENOBUFS && *can_increase) {
+                               switch (netlink_socket_double_buffer_sizes(s,
+                                   NETLINK_MAX_RECEIVE_BUFSIZE)) {
+                               case -1: break;
+                               case 0:
+                                       log_info("netlink", "netlink receive buffer too small, retry with larger one");
+                                       flags = 0;
+                                       goto retry;
+                               case 1:
+                                       *can_increase = 0;
+                                       break;
+                               }
+                       }
                        log_warn("netlink", "unable to receive netlink answer");
                        ret = -1;
                        goto out;
@@ -696,7 +749,8 @@ netlink_change_cb(struct lldpd *cfg)
                return;
        netlink_recv(cfg->g_netlink->nl_socket,
            cfg->g_netlink->devices,
-           cfg->g_netlink->addresses);
+           cfg->g_netlink->addresses,
+           &cfg->g_netlink->can_increase);
 }
 
 /**
@@ -737,12 +791,13 @@ netlink_initialize(struct lldpd *cfg)
        }
        TAILQ_INIT(ifs);
 
+       cfg->g_netlink->can_increase = 1;
        if (netlink_send(s, RTM_GETADDR, AF_UNSPEC, 1) == -1)
                goto end;
-       netlink_recv(s, NULL, ifaddrs);
+       netlink_recv(s, NULL, ifaddrs, &cfg->g_netlink->can_increase);
        if (netlink_send(s, RTM_GETLINK, AF_PACKET, 2) == -1)
                goto end;
-       netlink_recv(s, ifs, NULL);
+       netlink_recv(s, ifs, NULL, &cfg->g_netlink->can_increase);
 
        /* Listen to any future change */
        cfg->g_iface_cb = netlink_change_cb;