1#include <errno.h>
2#include <string.h>
3#include <syscall.h>
4#include <sys/socket.h>
5#include "netlink.h"
6
7static int __netlink_enumerate(int fd, unsigned int seq, int type, int af,
8	int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
9{
10	struct nlmsghdr *h;
11	union {
12		uint8_t buf[8192];
13		struct {
14			struct nlmsghdr nlh;
15			struct rtgenmsg g;
16		} req;
17		struct nlmsghdr reply;
18	} u;
19	int r, ret;
20
21	memset(&u.req, 0, sizeof(u.req));
22	u.req.nlh.nlmsg_len = sizeof(u.req);
23	u.req.nlh.nlmsg_type = type;
24	u.req.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
25	u.req.nlh.nlmsg_seq = seq;
26	u.req.g.rtgen_family = af;
27	r = send(fd, &u.req, sizeof(u.req), 0);
28	if (r < 0) return r;
29
30	while (1) {
31		r = recv(fd, u.buf, sizeof(u.buf), MSG_DONTWAIT);
32		if (r <= 0) return -1;
33		for (h = &u.reply; NLMSG_OK(h, (void*)&u.buf[r]); h = NLMSG_NEXT(h)) {
34			if (h->nlmsg_type == NLMSG_DONE) return 0;
35			if (h->nlmsg_type == NLMSG_ERROR) return -1;
36			ret = cb(ctx, h);
37			if (ret) return ret;
38		}
39	}
40}
41
42int __rtnetlink_enumerate(int link_af, int addr_af, int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
43{
44	int fd, r;
45
46	fd = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE);
47	if (fd < 0) return -1;
48	r = __netlink_enumerate(fd, 1, RTM_GETLINK, link_af, cb, ctx);
49	if (!r) r = __netlink_enumerate(fd, 2, RTM_GETADDR, addr_af, cb, ctx);
50	__syscall(SYS_close,fd);
51	return r;
52}
53