1 /*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2012 Roy Marples <roy@marples.name>
4 * All rights reserved
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/types.h>
29
30 #include "config.h"
31 #include "dhcpcd.h"
32 #include "if-pref.h"
33 #include "net.h"
34
35 /* Interface comparer for working out ordering. */
36 static int
ifcmp(struct interface * si,struct interface * ti)37 ifcmp(struct interface *si, struct interface *ti)
38 {
39 int sill, till;
40
41 if (si->state && !ti->state)
42 return -1;
43 if (!si->state && ti->state)
44 return 1;
45 if (!si->state && !ti->state)
46 return 0;
47 /* If one has a lease and the other not, it takes precedence. */
48 if (si->state->new && !ti->state->new)
49 return -1;
50 if (!si->state->new && ti->state->new)
51 return 1;
52 /* If we are either, they neither have a lease, or they both have.
53 * We need to check for IPv4LL and make it non-preferred. */
54 if (si->state->new && ti->state->new) {
55 sill = (si->state->new->cookie == htonl(MAGIC_COOKIE));
56 till = (ti->state->new->cookie == htonl(MAGIC_COOKIE));
57 if (!sill && till)
58 return 1;
59 if (sill && !till)
60 return -1;
61 }
62 /* Then carrier status. */
63 if (si->carrier > ti->carrier)
64 return -1;
65 if (si->carrier < ti->carrier)
66 return 1;
67 /* Finally, metric */
68 if (si->metric < ti->metric)
69 return -1;
70 if (si->metric > ti->metric)
71 return 1;
72 return 0;
73 }
74
75 /* Sort the interfaces into a preferred order - best first, worst last. */
76 void
sort_interfaces(void)77 sort_interfaces(void)
78 {
79 struct interface *sorted, *ifp, *ifn, *ift;
80
81 if (!ifaces || !ifaces->next)
82 return;
83 sorted = ifaces;
84 ifaces = ifaces->next;
85 sorted->next = NULL;
86 for (ifp = ifaces; ifp && (ifn = ifp->next, 1); ifp = ifn) {
87 /* Are we the new head? */
88 if (ifcmp(ifp, sorted) == -1) {
89 ifp->next = sorted;
90 sorted = ifp;
91 continue;
92 }
93 /* Do we fit in the middle? */
94 for (ift = sorted; ift->next; ift = ift->next) {
95 if (ifcmp(ifp, ift->next) == -1) {
96 ifp->next = ift->next;
97 ift->next = ifp;
98 break;
99 }
100 }
101 /* We must be at the end */
102 if (!ift->next) {
103 ift->next = ifp;
104 ifp->next = NULL;
105 }
106 }
107 ifaces = sorted;
108 }
109