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
parse_attrs(const struct nlattr * attr,void * data)23 int 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
family_id_cb(const struct nlmsghdr * nlh,void * data)33 static 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
msg_send(struct nlmsghdr * nlh)48 static 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
msg_recv(struct mnl_socket * nl,mnl_cb_t callback,void * data,int seq)74 static 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
msg_query(struct nlmsghdr * nlh,mnl_cb_t callback,void * data)97 static 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
get_family(void)112 static 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
msg_doit(struct nlmsghdr * nlh,mnl_cb_t callback,void * data)137 int 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
msg_dumpit(struct nlmsghdr * nlh,mnl_cb_t callback,void * data)143 int 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
msg_init(char * buf,int cmd)149 struct 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