netlink.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4 
1/*
2 * Netlink helper functions for driver wrappers
3 * Copyright (c) 2002-2009, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9#include "includes.h"
10
11#include "common.h"
12#include "eloop.h"
13#include "priv_netlink.h"
14#include "netlink.h"
15
16
17struct netlink_data {
18	struct netlink_config *cfg;
19	int sock;
20};
21
22
23static void netlink_receive_link(struct netlink_data *netlink,
24				 void (*cb)(void *ctx, struct ifinfomsg *ifi,
25					    u8 *buf, size_t len),
26				 struct nlmsghdr *h)
27{
28	if (cb == NULL || NLMSG_PAYLOAD(h, 0) < sizeof(struct ifinfomsg))
29		return;
30	cb(netlink->cfg->ctx, NLMSG_DATA(h),
31	   (u8 *) NLMSG_DATA(h) + NLMSG_ALIGN(sizeof(struct ifinfomsg)),
32	   NLMSG_PAYLOAD(h, sizeof(struct ifinfomsg)));
33}
34
35
36static void netlink_receive(int sock, void *eloop_ctx, void *sock_ctx)
37{
38	struct netlink_data *netlink = eloop_ctx;
39	char buf[8192];
40	int left;
41	struct sockaddr_nl from;
42	socklen_t fromlen;
43	struct nlmsghdr *h;
44	int max_events = 10;
45
46try_again:
47	fromlen = sizeof(from);
48	left = recvfrom(sock, buf, sizeof(buf), MSG_DONTWAIT,
49			(struct sockaddr *) &from, &fromlen);
50	if (left < 0) {
51		if (errno != EINTR && errno != EAGAIN)
52			wpa_printf(MSG_INFO, "netlink: recvfrom failed: %s",
53				   strerror(errno));
54		return;
55	}
56
57	h = (struct nlmsghdr *) buf;
58	while (NLMSG_OK(h, left)) {
59		switch (h->nlmsg_type) {
60		case RTM_NEWLINK:
61			netlink_receive_link(netlink, netlink->cfg->newlink_cb,
62					     h);
63			break;
64		case RTM_DELLINK:
65			netlink_receive_link(netlink, netlink->cfg->dellink_cb,
66					     h);
67			break;
68		}
69
70		h = NLMSG_NEXT(h, left);
71	}
72
73	if (left > 0) {
74		wpa_printf(MSG_DEBUG, "netlink: %d extra bytes in the end of "
75			   "netlink message", left);
76	}
77
78	if (--max_events > 0) {
79		/*
80		 * Try to receive all events in one eloop call in order to
81		 * limit race condition on cases where AssocInfo event, Assoc
82		 * event, and EAPOL frames are received more or less at the
83		 * same time. We want to process the event messages first
84		 * before starting EAPOL processing.
85		 */
86		goto try_again;
87	}
88}
89
90
91struct netlink_data * netlink_init(struct netlink_config *cfg)
92{
93	struct netlink_data *netlink;
94	struct sockaddr_nl local;
95
96	netlink = os_zalloc(sizeof(*netlink));
97	if (netlink == NULL)
98		return NULL;
99
100	netlink->cfg = cfg;
101
102	netlink->sock = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
103	if (netlink->sock < 0) {
104		wpa_printf(MSG_ERROR, "netlink: Failed to open netlink "
105			   "socket: %s", strerror(errno));
106		netlink_deinit(netlink);
107		return NULL;
108	}
109
110	os_memset(&local, 0, sizeof(local));
111	local.nl_family = AF_NETLINK;
112	local.nl_groups = RTMGRP_LINK;
113	if (bind(netlink->sock, (struct sockaddr *) &local, sizeof(local)) < 0)
114	{
115		wpa_printf(MSG_ERROR, "netlink: Failed to bind netlink "
116			   "socket: %s", strerror(errno));
117		netlink_deinit(netlink);
118		return NULL;
119	}
120
121	eloop_register_read_sock(netlink->sock, netlink_receive, netlink,
122				 NULL);
123
124	return netlink;
125}
126
127
128void netlink_deinit(struct netlink_data *netlink)
129{
130	if (netlink == NULL)
131		return;
132	if (netlink->sock >= 0) {
133		eloop_unregister_read_sock(netlink->sock);
134		close(netlink->sock);
135	}
136	os_free(netlink->cfg);
137	os_free(netlink);
138}
139
140int netlink_send_oper_ifla(struct netlink_data *netlink, int ifindex,
141			   int linkmode, int operstate)
142{
143	struct {
144		struct nlmsghdr hdr;
145		struct ifinfomsg ifinfo;
146		char opts[16];
147	} req;
148	struct rtattr *rta;
149	static int nl_seq;
150	ssize_t ret;
151
152	os_memset(&req, 0, sizeof(req));
153
154	req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
155	req.hdr.nlmsg_type = RTM_SETLINK;
156	req.hdr.nlmsg_flags = NLM_F_REQUEST;
157	req.hdr.nlmsg_seq = ++nl_seq;
158	req.hdr.nlmsg_pid = 0;
159
160	req.ifinfo.ifi_family = AF_UNSPEC;
161	req.ifinfo.ifi_type = 0;
162	req.ifinfo.ifi_index = ifindex;
163	req.ifinfo.ifi_flags = 0;
164	req.ifinfo.ifi_change = 0;
165
166	if (linkmode != -1) {
167		rta = aliasing_hide_typecast(
168			((char *) &req + NLMSG_ALIGN(req.hdr.nlmsg_len)),
169			struct rtattr);
170		rta->rta_type = IFLA_LINKMODE;
171		rta->rta_len = RTA_LENGTH(sizeof(char));
172		*((char *) RTA_DATA(rta)) = linkmode;
173		req.hdr.nlmsg_len = NLMSG_ALIGN(req.hdr.nlmsg_len) +
174			RTA_LENGTH(sizeof(char));
175	}
176	if (operstate != -1) {
177		rta = aliasing_hide_typecast(
178			((char *) &req + NLMSG_ALIGN(req.hdr.nlmsg_len)),
179			struct rtattr);
180		rta->rta_type = IFLA_OPERSTATE;
181		rta->rta_len = RTA_LENGTH(sizeof(char));
182		*((char *) RTA_DATA(rta)) = operstate;
183		req.hdr.nlmsg_len = NLMSG_ALIGN(req.hdr.nlmsg_len) +
184			RTA_LENGTH(sizeof(char));
185	}
186
187	wpa_printf(MSG_DEBUG, "netlink: Operstate: linkmode=%d, operstate=%d",
188		   linkmode, operstate);
189
190	ret = send(netlink->sock, &req, req.hdr.nlmsg_len, 0);
191	if (ret < 0) {
192		wpa_printf(MSG_DEBUG, "netlink: Sending operstate IFLA "
193			   "failed: %s (assume operstate is not supported)",
194			   strerror(errno));
195	}
196
197	return ret < 0 ? -1 : 0;
198}
199