netdev implementation for FreeBSD

This patch adds new netdev classes that implement
"system" and "tap" devices on FreeBSD using the
libpcap library. This enables the use of the
"netdev" datapath_type of Open vSwitch on FreeBSD.

Signed-off-by: Gaetano Catalli <gaetano.catalli@gmail.com>
Signed-off-by: Ed Maste <emaste@adaranet.com>
Signed-off-by: Giuseppe Lettieri <g.lettieri@iet.unipi.it>
Signed-off-by: Ben Pfaff <blp@nicira.com>

lib/rtbsd.c

@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2011 Gaetano Catalli.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/route.h>
+#include <poll.h>
+
+#include "coverage.h"
+#include "socket-util.h"
+#include "poll-loop.h"
+#include "vlog.h"
+#include "rtbsd.h"
+
+VLOG_DEFINE_THIS_MODULE(rtbsd);
+COVERAGE_DEFINE(rtbsd_changed);
+
+/* PF_ROUTE socket. */
+static int notify_sock = -1;
+
+/* All registered notifiers. */
+static struct list all_notifiers = LIST_INITIALIZER(&all_notifiers);
+
+static void rtbsd_report_change(const struct if_msghdr *);
+static void rtbsd_report_notify_error(void);
+
+/* Registers 'cb' to be called with auxiliary data 'aux' with network device
+ * change notifications.  The notifier is stored in 'notifier', which the
+ * caller must not modify or free.
+ *
+ * Returns 0 if successful, otherwise a positive errno value. */
+int
+rtbsd_notifier_register(struct rtbsd_notifier *notifier,
+                            rtbsd_notify_func *cb, void *aux)
+{
+    if (notify_sock < 0) {
+        int error;
+        notify_sock = socket(PF_ROUTE, SOCK_RAW, 0);
+        if (notify_sock < 0) {
+            VLOG_WARN("could not create PF_ROUTE socket: %s",
+                      strerror(errno));
+            return errno;
+        }
+        error = set_nonblocking(notify_sock);
+        if (error) {
+            VLOG_WARN("error set_nonblocking PF_ROUTE socket: %s",
+                    strerror(error));
+            return error;
+        }
+    } else {
+        /* Catch up on notification work so that the new notifier won't
+         * receive any stale notifications. XXX*/
+        rtbsd_notifier_run();
+    }
+
+    list_push_back(&all_notifiers, &notifier->node);
+    notifier->cb = cb;
+    notifier->aux = aux;
+    return 0;
+}
+
+/* Cancels notification on 'notifier', which must have previously been
+ * registered with rtbsd_notifier_register(). */
+void
+rtbsd_notifier_unregister(struct rtbsd_notifier *notifier)
+{
+    list_remove(&notifier->node);
+    if (list_is_empty(&all_notifiers)) {
+        close(notify_sock);
+        notify_sock = -1;
+    }
+}
+
+/* Calls all of the registered notifiers, passing along any as-yet-unreported
+ * netdev change events. */
+void
+rtbsd_notifier_run(void)
+{
+    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+    struct if_msghdr msg;
+    if (notify_sock < 0) {
+        return;
+    }
+
+    for (;;) {
+        int retval;
+
+        msg.ifm_type = RTM_IFINFO;
+        msg.ifm_version = RTM_VERSION; //XXX check if necessary
+
+        /* read from PF_ROUTE socket */
+        retval = read(notify_sock, (char *)&msg, sizeof(msg));
+        if (retval >= 0) {
+            /* received packet from PF_ROUTE socket
+             * XXX check for bad packets */
+            if (msg.ifm_type == RTM_IFINFO) {
+                rtbsd_report_change(&msg);
+            }
+        } else if (errno == EAGAIN) {
+            return;
+        } else {
+            if (errno == ENOBUFS) {
+                VLOG_WARN_RL(&rl, "PF_ROUTE receive buffer overflowed");
+            } else {
+                VLOG_WARN_RL(&rl, "error reading PF_ROUTE socket: %s",
+                             strerror(errno));
+            }
+            rtbsd_report_notify_error();
+        }
+    }
+}
+
+/* Causes poll_block() to wake up when network device change notifications are
+ * ready. */
+void
+rtbsd_notifier_wait(void)
+{
+    if (notify_sock >= 0) {
+        poll_fd_wait(notify_sock, POLLIN);
+    }
+}
+
+static void
+rtbsd_report_change(const struct if_msghdr *msg)
+{
+    struct rtbsd_notifier *notifier;
+    struct rtbsd_change change;
+
+    COVERAGE_INC(rtbsd_changed);
+
+    change.msg_type = msg->ifm_type; //XXX
+    change.if_index = msg->ifm_index;
+    if_indextoname(msg->ifm_index, change.if_name);
+    change.master_ifindex = 0; //XXX
+
+    LIST_FOR_EACH (notifier, node, &all_notifiers) {
+        notifier->cb(&change, notifier->aux);
+    }
+}
+
+/* If an error occurs the notifiers' callbacks are called with NULL changes */
+static void
+rtbsd_report_notify_error(void)
+{
+    struct rtbsd_notifier *notifier;
+
+    LIST_FOR_EACH (notifier, node, &all_notifiers) {
+        notifier->cb(NULL, notifier->aux);
+    }
+}