busybox/networking/libiproute/ll_map.c

/* vi: set sw=4 ts=4: */
/*
 * ll_map.c
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 */

#include "libbb.h"
#include <string.h>

#include "libnetlink.h"
#include "ll_map.h"

#include <sys/socket.h>	/* socket() */
#include <net/if.h>	/* struct ifreq and co. */
#include <sys/ioctl.h>	/* ioctl() & SIOCGIFINDEX */

struct idxmap {
	struct idxmap * next;
	int		index;
	int		type;
	int		alen;
	unsigned	flags;
	unsigned char	addr[8];
	char		name[16];
};

static struct idxmap *idxmap[16];

int ll_remember_index(struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
{
	int h;
	struct ifinfomsg *ifi = NLMSG_DATA(n);
	struct idxmap *im, **imp;
	struct rtattr *tb[IFLA_MAX+1];

	if (n->nlmsg_type != RTM_NEWLINK)
		return 0;

	if (n->nlmsg_len < NLMSG_LENGTH(sizeof(ifi)))
		return -1;


	memset(tb, 0, sizeof(tb));
	parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));
	if (tb[IFLA_IFNAME] == NULL)
		return 0;

	h = ifi->ifi_index&0xF;

	for (imp = &idxmap[h]; (im = *imp) != NULL; imp = &im->next)
		if (im->index == ifi->ifi_index)
			break;

	if (im == NULL) {
		im = xmalloc(sizeof(*im));
		im->next = *imp;
		im->index = ifi->ifi_index;
		*imp = im;
	}

	im->type = ifi->ifi_type;
	im->flags = ifi->ifi_flags;
	if (tb[IFLA_ADDRESS]) {
		int alen;
		im->alen = alen = RTA_PAYLOAD(tb[IFLA_ADDRESS]);
		if (alen > sizeof(im->addr))
			alen = sizeof(im->addr);
		memcpy(im->addr, RTA_DATA(tb[IFLA_ADDRESS]), alen);
	} else {
		im->alen = 0;
		memset(im->addr, 0, sizeof(im->addr));
	}
	strcpy(im->name, RTA_DATA(tb[IFLA_IFNAME]));
	return 0;
}

const char *ll_idx_n2a(int idx, char *buf)
{
	struct idxmap *im;

	if (idx == 0)
		return "*";
	for (im = idxmap[idx & 0xF]; im; im = im->next)
		if (im->index == idx)
			return im->name;
	snprintf(buf, 16, "if%d", idx);
	return buf;
}


const char *ll_index_to_name(int idx)
{
	static char nbuf[16];

	return ll_idx_n2a(idx, nbuf);
}

int ll_index_to_type(int idx)
{
	struct idxmap *im;

	if (idx == 0)
		return -1;
	for (im = idxmap[idx & 0xF]; im; im = im->next)
		if (im->index == idx)
			return im->type;
	return -1;
}

unsigned ll_index_to_flags(int idx)
{
	struct idxmap *im;

	if (idx == 0)
		return 0;

	for (im = idxmap[idx & 0xF]; im; im = im->next)
		if (im->index == idx)
			return im->flags;
	return 0;
}

// TODO: caching is not warranted - no users which repeatedly call it
int xll_name_to_index(const char * const name)
{
	static char ncache[16];
	static int icache;

	struct idxmap *im;
	int sock_fd;
	int i;
	int ret = 0;

	if (name == NULL)
		goto out;
	if (icache && strcmp(name, ncache) == 0) {
		ret = icache;
		goto out;
	}
	for (i = 0; i < 16; i++) {
		for (im = idxmap[i]; im; im = im->next) {
			if (strcmp(im->name, name) == 0) {
				icache = im->index;
				strcpy(ncache, name);
				ret = im->index;
				goto out;
			}
		}
	}
	/* We have not found the interface in our cache, but the kernel
	 * may still know about it. One reason is that we may be using
	 * module on-demand loading, which means that the kernel will
	 * load the module and make the interface exist only when
	 * we explicitely request it (check for dev_load() in net/core/dev.c).
	 * I can think of other similar scenario, but they are less common...
	 * Jean II */
	sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock_fd) {
		struct ifreq ifr;
		int tmp;
		strncpy(ifr.ifr_name, name, IFNAMSIZ);
		ifr.ifr_ifindex = -1;
		tmp = ioctl(sock_fd, SIOCGIFINDEX, &ifr);
		close(sock_fd);
		if (tmp >= 0)
			/* In theory, we should redump the interface list
			 * to update our cache, this is left as an exercise
			 * to the reader... Jean II */
			ret = ifr.ifr_ifindex;
	}
out:
	if (ret <= 0)
		bb_error_msg_and_die("cannot find device \"%s\"", name);
	return ret;
}

int ll_init_map(struct rtnl_handle *rth)
{
	xrtnl_wilddump_request(rth, AF_UNSPEC, RTM_GETLINK);
	xrtnl_dump_filter(rth, ll_remember_index, &idxmap);
	return 0;
}