1/*
2 * libgenl.c	GENL library
3 */
4
5#include <stdio.h>
6#include <stdlib.h>
7#include <unistd.h>
8
9#include <linux/genetlink.h>
10#include "libgenl.h"
11
12static int genl_parse_getfamily(struct nlmsghdr *nlh)
13{
14	struct rtattr *tb[CTRL_ATTR_MAX + 1];
15	struct genlmsghdr *ghdr = NLMSG_DATA(nlh);
16	int len = nlh->nlmsg_len;
17	struct rtattr *attrs;
18
19	if (nlh->nlmsg_type != GENL_ID_CTRL) {
20		fprintf(stderr, "Not a controller message, nlmsg_len=%d "
21			"nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type);
22		return -1;
23	}
24
25	len -= NLMSG_LENGTH(GENL_HDRLEN);
26
27	if (len < 0) {
28		fprintf(stderr, "wrong controller message len %d\n", len);
29		return -1;
30	}
31
32	if (ghdr->cmd != CTRL_CMD_NEWFAMILY) {
33		fprintf(stderr, "Unknown controller command %d\n", ghdr->cmd);
34		return -1;
35	}
36
37	attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
38	parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
39
40	if (tb[CTRL_ATTR_FAMILY_ID] == NULL) {
41		fprintf(stderr, "Missing family id TLV\n");
42		return -1;
43	}
44
45	return rta_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);
46}
47
48int genl_resolve_family(struct rtnl_handle *grth, const char *family)
49{
50	GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
51		     NLM_F_REQUEST);
52
53	addattr_l(&req.n, sizeof(req), CTRL_ATTR_FAMILY_NAME,
54		  family, strlen(family) + 1);
55
56	if (rtnl_talk(grth, &req.n, &req.n, sizeof(req)) < 0) {
57		fprintf(stderr, "Error talking to the kernel\n");
58		return -2;
59	}
60
61	return genl_parse_getfamily(&req.n);
62}
63
64