1/*	$OpenBSD: carp.c,v 1.3 2009/09/30 12:22:03 claudio Exp $ */
2
3/*
4 * Copyright (c) 2006 Henning Brauer <henning@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include <sys/types.h>
20#include <sys/socket.h>
21#include <sys/ioctl.h>
22#include <net/if.h>
23
24#include <errno.h>
25#include <string.h>
26#include <stdlib.h>
27#include <unistd.h>
28
29#include "ripd.h"
30#include "log.h"
31
32struct carpgroup {
33	TAILQ_ENTRY(carpgroup)	 entry;
34	char			*group;
35	int			 do_demote;
36	int			 changed_by;
37};
38
39TAILQ_HEAD(carpgroups, carpgroup)	carpgroups =
40    TAILQ_HEAD_INITIALIZER(carpgroups);
41
42struct carpgroup	*carp_group_find(char *group);
43int			 carp_demote_ioctl(char *, int);
44
45struct carpgroup *
46carp_group_find(char *group)
47{
48	struct carpgroup	*c;
49
50	TAILQ_FOREACH(c, &carpgroups, entry)
51		if (!strcmp(c->group, group))
52			return (c);
53
54	return (NULL);
55}
56
57int
58carp_demote_init(char *group, int force)
59{
60	struct carpgroup	*c;
61	int			 level;
62
63	if ((c = carp_group_find(group)) == NULL) {
64		if ((c = calloc(1, sizeof(struct carpgroup))) == NULL) {
65			log_warn("carp_demote_init calloc");
66			return (-1);
67		}
68		if ((c->group = strdup(group)) == NULL) {
69			log_warn("carp_demote_init strdup");
70			free(c);
71			return (-1);
72		}
73
74		/* only demote if this group already is demoted */
75		if ((level = carp_demote_get(group)) == -1) {
76			free(c->group);
77			free(c);
78			return (-1);
79		}
80		if (level > 0 || force)
81			c->do_demote = 1;
82
83		TAILQ_INSERT_TAIL(&carpgroups, c, entry);
84	}
85
86	return (0);
87}
88
89void
90carp_demote_shutdown(void)
91{
92	struct carpgroup	*c;
93
94	while ((c = TAILQ_FIRST(&carpgroups)) != NULL) {
95		TAILQ_REMOVE(&carpgroups, c, entry);
96		if (c->do_demote && c->changed_by > 0)
97			carp_demote_ioctl(c->group, -c->changed_by);
98
99		free(c->group);
100		free(c);
101	}
102}
103
104int
105carp_demote_get(char *group)
106{
107	int			s;
108	struct ifgroupreq	ifgr;
109
110	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
111		log_warn("carp_demote_get: socket");
112		return (-1);
113	}
114
115	bzero(&ifgr, sizeof(ifgr));
116	strlcpy(ifgr.ifgr_name, group, sizeof(ifgr.ifgr_name));
117
118	if (ioctl(s, SIOCGIFGATTR, (caddr_t)&ifgr) == -1) {
119		if (errno == ENOENT)
120			log_warnx("group \"%s\" does not exist", group);
121		else
122			log_warn("carp_demote_get: ioctl");
123		close(s);
124		return (-1);
125	}
126
127	close(s);
128	return ((int)ifgr.ifgr_attrib.ifg_carp_demoted);
129}
130
131int
132carp_demote_set(char *group, int demote)
133{
134	struct carpgroup	*c;
135
136	if ((c = carp_group_find(group)) == NULL) {
137		log_warnx("carp_group_find for %s returned NULL?!", group);
138		return (-1);
139	}
140
141	if (c->changed_by + demote < 0) {
142		log_warnx("carp_demote_set: changed_by + demote < 0");
143		return (-1);
144	}
145
146	if (c->do_demote && carp_demote_ioctl(group, demote) == -1)
147		return (-1);
148
149	c->changed_by += demote;
150
151	/* enable demotion when we return to 0, i. e. all sessions up */
152	if (demote < 0 && c->changed_by == 0)
153		c->do_demote = 1;
154
155	return (0);
156}
157
158int
159carp_demote_ioctl(char *group, int demote)
160{
161	int			s, res;
162	struct ifgroupreq	ifgr;
163
164	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
165		log_warn("carp_demote_get: socket");
166		return (-1);
167	}
168
169	bzero(&ifgr, sizeof(ifgr));
170	strlcpy(ifgr.ifgr_name, group, sizeof(ifgr.ifgr_name));
171	ifgr.ifgr_attrib.ifg_carp_demoted = demote;
172
173	if ((res = ioctl(s, SIOCSIFGATTR, (caddr_t)&ifgr)) == -1)
174		log_warn("unable to %s the demote state "
175		    "of group '%s'", (demote > 0) ? "increment" : "decrement",
176		    group);
177	else
178		log_info("%s the demote state of group '%s'",
179		    (demote > 0) ? "incremented" : "decremented", group);
180
181	close(s);
182	return (res);
183}
184