1/*
2 * msg.c	Messaging (netlink) helper functions.
3 *
4 *		This program is free software; you can redistribute it and/or
5 *		modify it under the terms of the GNU General Public License
6 *		as published by the Free Software Foundation; either version
7 *		2 of the License, or (at your option) any later version.
8 *
9 * Authors:	Richard Alpe <richard.alpe@ericsson.com>
10 */
11
12#include <stdio.h>
13#include <time.h>
14#include <errno.h>
15
16#include <linux/tipc_netlink.h>
17#include <linux/tipc.h>
18#include <linux/genetlink.h>
19#include <libmnl/libmnl.h>
20
21#include "msg.h"
22
23int parse_attrs(const struct nlattr *attr, void *data)
24{
25	const struct nlattr **tb = data;
26	int type = mnl_attr_get_type(attr);
27
28	tb[type] = attr;
29
30	return MNL_CB_OK;
31}
32
33static int family_id_cb(const struct nlmsghdr *nlh, void *data)
34{
35	struct nlattr *tb[CTRL_ATTR_MAX + 1] = {};
36	struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);
37	int *id = data;
38
39	mnl_attr_parse(nlh, sizeof(*genl), parse_attrs, tb);
40	if (!tb[CTRL_ATTR_FAMILY_ID])
41		return MNL_CB_ERROR;
42
43	*id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
44
45	return MNL_CB_OK;
46}
47
48static struct mnl_socket *msg_send(struct nlmsghdr *nlh)
49{
50	int ret;
51	struct mnl_socket *nl;
52
53	nl = mnl_socket_open(NETLINK_GENERIC);
54	if (nl == NULL) {
55		perror("mnl_socket_open");
56		return NULL;
57	}
58
59	ret = mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID);
60	if (ret < 0) {
61		perror("mnl_socket_bind");
62		return NULL;
63	}
64
65	ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
66	if (ret < 0) {
67		perror("mnl_socket_send");
68		return NULL;
69	}
70
71	return nl;
72}
73
74static int msg_recv(struct mnl_socket *nl, mnl_cb_t callback, void *data, int seq)
75{
76	int ret;
77	unsigned int portid;
78	char buf[MNL_SOCKET_BUFFER_SIZE];
79
80	portid = mnl_socket_get_portid(nl);
81
82	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
83	while (ret > 0) {
84		ret = mnl_cb_run(buf, ret, seq, portid, callback, data);
85		if (ret <= 0)
86			break;
87		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
88	}
89	if (ret == -1)
90		perror("error");
91
92	mnl_socket_close(nl);
93
94	return ret;
95}
96
97static int msg_query(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
98{
99	unsigned int seq;
100	struct mnl_socket *nl;
101
102	seq = time(NULL);
103	nlh->nlmsg_seq = seq;
104
105	nl = msg_send(nlh);
106	if (!nl)
107		return -ENOTSUP;
108
109	return msg_recv(nl, callback, data, seq);
110}
111
112static int get_family(void)
113{
114	int err;
115	int nl_family;
116	struct nlmsghdr *nlh;
117	struct genlmsghdr *genl;
118	char buf[MNL_SOCKET_BUFFER_SIZE];
119
120	nlh = mnl_nlmsg_put_header(buf);
121	nlh->nlmsg_type	= GENL_ID_CTRL;
122	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
123
124	genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
125	genl->cmd = CTRL_CMD_GETFAMILY;
126	genl->version = 1;
127
128	mnl_attr_put_u32(nlh, CTRL_ATTR_FAMILY_ID, GENL_ID_CTRL);
129	mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, TIPC_GENL_V2_NAME);
130
131	if ((err = msg_query(nlh, family_id_cb, &nl_family)))
132		return err;
133
134	return nl_family;
135}
136
137int msg_doit(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
138{
139	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
140	return msg_query(nlh, callback, data);
141}
142
143int msg_dumpit(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
144{
145	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
146	return msg_query(nlh, callback, data);
147}
148
149struct nlmsghdr *msg_init(char *buf, int cmd)
150{
151	int family;
152	struct nlmsghdr *nlh;
153	struct genlmsghdr *genl;
154
155	family = get_family();
156	if (family <= 0) {
157		fprintf(stderr,
158			"Unable to get TIPC nl family id (module loaded?)\n");
159		return NULL;
160	}
161
162	nlh = mnl_nlmsg_put_header(buf);
163	nlh->nlmsg_type	= family;
164
165	genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
166	genl->cmd = cmd;
167	genl->version = 1;
168
169	return nlh;
170}
171