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5
6#include <errno.h>
7#include <stdio.h>
8#include <stdlib.h>
9#include <unistd.h>
10
11#include <linux/genetlink.h>
12#include "libgenl.h"
13
14static int genl_parse_getfamily(struct nlmsghdr *nlh)
15{
16 struct rtattr *tb[CTRL_ATTR_MAX + 1];
17 struct genlmsghdr *ghdr = NLMSG_DATA(nlh);
18 int len = nlh->nlmsg_len;
19 struct rtattr *attrs;
20
21 if (nlh->nlmsg_type != GENL_ID_CTRL) {
22 fprintf(stderr, "Not a controller message, nlmsg_len=%d "
23 "nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type);
24 return -1;
25 }
26
27 len -= NLMSG_LENGTH(GENL_HDRLEN);
28
29 if (len < 0) {
30 fprintf(stderr, "wrong controller message len %d\n", len);
31 return -1;
32 }
33
34 if (ghdr->cmd != CTRL_CMD_NEWFAMILY) {
35 fprintf(stderr, "Unknown controller command %d\n", ghdr->cmd);
36 return -1;
37 }
38
39 attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
40 parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
41
42 if (tb[CTRL_ATTR_FAMILY_ID] == NULL) {
43 fprintf(stderr, "Missing family id TLV\n");
44 return -1;
45 }
46
47 return rta_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);
48}
49
50int genl_resolve_family(struct rtnl_handle *grth, const char *family)
51{
52 GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
53 NLM_F_REQUEST);
54 struct nlmsghdr *answer;
55 int fnum;
56
57 addattr_l(&req.n, sizeof(req), CTRL_ATTR_FAMILY_NAME,
58 family, strlen(family) + 1);
59
60 if (rtnl_talk(grth, &req.n, &answer) < 0) {
61 fprintf(stderr, "Error talking to the kernel\n");
62 return -2;
63 }
64
65 fnum = genl_parse_getfamily(answer);
66 free(answer);
67
68 return fnum;
69}
70
71static int genl_parse_grps(struct rtattr *attr, const char *name, unsigned int *id)
72{
73 const struct rtattr *pos;
74
75 rtattr_for_each_nested(pos, attr) {
76 struct rtattr *tb[CTRL_ATTR_MCAST_GRP_MAX + 1];
77
78 parse_rtattr_nested(tb, CTRL_ATTR_MCAST_GRP_MAX, pos);
79
80 if (tb[CTRL_ATTR_MCAST_GRP_NAME] && tb[CTRL_ATTR_MCAST_GRP_ID]) {
81 if (strcmp(name, rta_getattr_str(tb[CTRL_ATTR_MCAST_GRP_NAME])) == 0) {
82 *id = rta_getattr_u32(tb[CTRL_ATTR_MCAST_GRP_ID]);
83 return 0;
84 }
85 }
86 }
87
88 errno = ENOENT;
89 return -1;
90}
91
92int genl_add_mcast_grp(struct rtnl_handle *grth, __u16 fnum, const char *group)
93{
94 GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
95 NLM_F_REQUEST);
96 struct rtattr *tb[CTRL_ATTR_MAX + 1];
97 struct nlmsghdr *answer = NULL;
98 struct genlmsghdr *ghdr;
99 struct rtattr *attrs;
100 int len, ret = -1;
101 unsigned int id;
102
103 addattr16(&req.n, sizeof(req), CTRL_ATTR_FAMILY_ID, fnum);
104
105 if (rtnl_talk(grth, &req.n, &answer) < 0) {
106 fprintf(stderr, "Error talking to the kernel\n");
107 return -2;
108 }
109
110 ghdr = NLMSG_DATA(answer);
111 len = answer->nlmsg_len;
112
113 if (answer->nlmsg_type != GENL_ID_CTRL) {
114 errno = EINVAL;
115 goto err_free;
116 }
117
118 len -= NLMSG_LENGTH(GENL_HDRLEN);
119 if (len < 0) {
120 errno = EINVAL;
121 goto err_free;
122 }
123
124 attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
125 parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
126
127 if (tb[CTRL_ATTR_MCAST_GROUPS] == NULL) {
128 errno = ENOENT;
129 fprintf(stderr, "Missing mcast groups TLV\n");
130 goto err_free;
131 }
132
133 if (genl_parse_grps(tb[CTRL_ATTR_MCAST_GROUPS], group, &id) < 0)
134 goto err_free;
135
136 ret = rtnl_add_nl_group(grth, id);
137
138err_free:
139 free(answer);
140 return ret;
141}
142
143int genl_init_handle(struct rtnl_handle *grth, const char *family,
144 int *genl_family)
145{
146 if (*genl_family >= 0)
147 return 0;
148
149 if (rtnl_open_byproto(grth, 0, NETLINK_GENERIC) < 0) {
150 fprintf(stderr, "Cannot open generic netlink socket\n");
151 return -1;
152 }
153
154 *genl_family = genl_resolve_family(grth, family);
155 if (*genl_family < 0)
156 return -1;
157
158 return 0;
159}
160
