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-rw-r--r--if-pref.c108
1 files changed, 108 insertions, 0 deletions
diff --git a/if-pref.c b/if-pref.c
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+/*
+ * dhcpcd - DHCP client daemon
+ * Copyright (c) 2006-2010 Roy Marples <roy@marples.name>
+ * All rights reserved
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+
+#include "config.h"
+#include "dhcpcd.h"
+#include "if-pref.h"
+#include "net.h"
+
+/* Interface comparer for working out ordering. */
+static int
+ifcmp(struct interface *si, struct interface *ti)
+{
+ int sill, till;
+
+ if (si->state && !ti->state)
+ return -1;
+ if (!si->state && ti->state)
+ return 1;
+ if (!si->state && !ti->state)
+ return 0;
+ /* If one has a lease and the other not, it takes precedence. */
+ if (si->state->new && !ti->state->new)
+ return -1;
+ if (!si->state->new && ti->state->new)
+ return 1;
+ /* If we are either, they neither have a lease, or they both have.
+ * We need to check for IPv4LL and make it non-preferred. */
+ if (si->state->new && ti->state->new) {
+ sill = (si->state->new->cookie == htonl(MAGIC_COOKIE));
+ till = (ti->state->new->cookie == htonl(MAGIC_COOKIE));
+ if (!sill && till)
+ return -1;
+ if (sill && !till)
+ return 1;
+ }
+ /* Then carrier status. */
+ if (si->carrier > ti->carrier)
+ return -1;
+ if (si->carrier < ti->carrier)
+ return 1;
+ /* Finally, metric */
+ if (si->metric < ti->metric)
+ return -1;
+ if (si->metric > ti->metric)
+ return 1;
+ return 0;
+}
+
+/* Sort the interfaces into a preferred order - best first, worst last. */
+void
+sort_interfaces(void)
+{
+ struct interface *sorted, *ifp, *ifn, *ift;
+
+ if (!ifaces || !ifaces->next)
+ return;
+ sorted = ifaces;
+ ifaces = ifaces->next;
+ sorted->next = NULL;
+ for (ifp = ifaces; ifp && (ifn = ifp->next, 1); ifp = ifn) {
+ /* Are we the new head? */
+ if (ifcmp(ifp, sorted) == -1) {
+ ifp->next = sorted;
+ sorted = ifp;
+ continue;
+ }
+ /* Do we fit in the middle? */
+ for (ift = sorted; ift->next; ift = ift->next) {
+ if (ifcmp(ifp, ift->next) == -1) {
+ ifp->next = ift->next;
+ ift->next = ifp;
+ break;
+ }
+ }
+ /* We must be at the end */
+ if (!ift->next) {
+ ift->next = ifp;
+ ifp->next = NULL;
+ }
+ }
+ ifaces = sorted;
+}