/*

 * 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 <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <string.h>

#include <net/if.h>

#include "libnetlink.h"

#include "ll_map.h"

#include "list.h"

struct ll_cache {

	struct hlist_node idx_hash;

	struct hlist_node name_hash;

	unsigned	flags;

	unsigned 	index;

	unsigned short	type;

	char		name[];

};

#define IDXMAP_SIZE	1024

static struct hlist_head idx_head[IDXMAP_SIZE];

static struct hlist_head name_head[IDXMAP_SIZE];

static struct ll_cache *ll_get_by_index(unsigned index)

{

	struct hlist_node *n;

	unsigned h = index & (IDXMAP_SIZE - 1);

	hlist_for_each(n, &idx_head[h]) {

		struct ll_cache *im

			= container_of(n, struct ll_cache, idx_hash);

		if (im->index == index)

			return im;

	}

	return NULL;

}

unsigned namehash(const char *str)

{

	unsigned hash = 5381;

	while (*str)

		hash = ((hash << 5) + hash) + *str++; /* hash * 33 + c */

	return hash;

}

static struct ll_cache *ll_get_by_name(const char *name)

{

	struct hlist_node *n;

	unsigned h = namehash(name) & (IDXMAP_SIZE - 1);

	hlist_for_each(n, &name_head[h]) {

		struct ll_cache *im

			= container_of(n, struct ll_cache, name_hash);

		if (strncmp(im->name, name, IFNAMSIZ) == 0)

			return im;

	}

	return NULL;

}

int ll_remember_index(struct nlmsghdr *n, void *arg)

{

	unsigned int h;

	const char *ifname;

	struct ifinfomsg *ifi = NLMSG_DATA(n);

	struct ll_cache *im;

	struct rtattr *tb[IFLA_MAX+1];

	if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)

		return 0;

	if (n->nlmsg_len < NLMSG_LENGTH(sizeof(*ifi)))

		return -1;

	im = ll_get_by_index(ifi->ifi_index);

	if (n->nlmsg_type == RTM_DELLINK) {

		if (im) {

			hlist_del(&im->name_hash);

			hlist_del(&im->idx_hash);

			free(im);

		}

		return 0;

	}

	parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));

	ifname = rta_getattr_str(tb[IFLA_IFNAME]);

	if (ifname == NULL)

		return 0;

	if (im) {

		/* change to existing entry */

		if (strcmp(im->name, ifname) != 0) {

			hlist_del(&im->name_hash);

			h = namehash(ifname) & (IDXMAP_SIZE - 1);

			hlist_add_head(&im->name_hash, &name_head[h]);

		}

		im->flags = ifi->ifi_flags;

		return 0;

	}

	im = malloc(sizeof(*im) + strlen(ifname) + 1);

	if (im == NULL)

		return 0;

	im->index = ifi->ifi_index;

	strcpy(im->name, ifname);

	im->type = ifi->ifi_type;

	im->flags = ifi->ifi_flags;

	h = ifi->ifi_index & (IDXMAP_SIZE - 1);

	hlist_add_head(&im->idx_hash, &idx_head[h]);

	h = namehash(ifname) & (IDXMAP_SIZE - 1);

	hlist_add_head(&im->name_hash, &name_head[h]);

	return 0;

}

const char *ll_idx_n2a(unsigned int idx)

{

	static char buf[IFNAMSIZ];

	snprintf(buf, sizeof(buf), "if%u", idx);

	return buf;

}

static unsigned int ll_idx_a2n(const char *name)

{

	unsigned int idx;

	if (sscanf(name, "if%u", &idx) != 1)

		return 0;

	return idx;

}

static int ll_link_get(const char *name, int index)

{

	struct {

		struct nlmsghdr		n;

		struct ifinfomsg	ifm;

		char			buf[1024];

	} req = {

		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),

		.n.nlmsg_flags = NLM_F_REQUEST,

		.n.nlmsg_type = RTM_GETLINK,

		.ifm.ifi_index = index,

	};

	__u32 filt_mask = RTEXT_FILTER_VF | RTEXT_FILTER_SKIP_STATS;

	struct rtnl_handle rth = {};

	struct nlmsghdr *answer;

	int rc = 0;

	if (rtnl_open(&rth, 0) < 0)

		return 0;

	addattr32(&req.n, sizeof(req), IFLA_EXT_MASK, filt_mask);

	if (name)

		addattr_l(&req.n, sizeof(req), IFLA_IFNAME, name,

			  strlen(name) + 1);

	if (rtnl_talk_suppress_rtnl_errmsg(&rth, &req.n, &answer) < 0)

		goto out;

	/* add entry to cache */

	rc  = ll_remember_index(answer, NULL);

	if (!rc) {

		struct ifinfomsg *ifm = NLMSG_DATA(answer);

		rc = ifm->ifi_index;

	}

	free(answer);

out:

	rtnl_close(&rth);

	return rc;

}

const char *ll_index_to_name(unsigned int idx)

{

	static char buf[IFNAMSIZ];

	const struct ll_cache *im;

	if (idx == 0)

		return "*";

	im = ll_get_by_index(idx);

	if (im)

		return im->name;

	if (ll_link_get(NULL, idx) == idx) {

		im = ll_get_by_index(idx);

		if (im)

			return im->name;

	}

	if (if_indextoname(idx, buf) == NULL)

		snprintf(buf, IFNAMSIZ, "if%u", idx);

	return buf;

}

int ll_index_to_type(unsigned idx)

{

	const struct ll_cache *im;

	if (idx == 0)

		return -1;

	im = ll_get_by_index(idx);

	return im ? im->type : -1;

}

int ll_index_to_flags(unsigned idx)

{

	const struct ll_cache *im;

	if (idx == 0)

		return 0;

	im = ll_get_by_index(idx);

	return im ? im->flags : -1;

}

unsigned ll_name_to_index(const char *name)

{

	const struct ll_cache *im;

	unsigned idx;

	if (name == NULL)

		return 0;

	im = ll_get_by_name(name);

	if (im)

		return im->index;

	idx = ll_link_get(name, 0);

	if (idx == 0)

		idx = if_nametoindex(name);

	if (idx == 0)

		idx = ll_idx_a2n(name);

	return idx;

}

void ll_drop_by_index(unsigned index)

{

	struct ll_cache *im;

	im = ll_get_by_index(index);

	if (!im)

		return;

	hlist_del(&im->idx_hash);

	hlist_del(&im->name_hash);

	free(im);

}

void ll_init_map(struct rtnl_handle *rth)

{

	static int initialized;

	if (initialized)

		return;

	if (rtnl_linkdump_req(rth, AF_UNSPEC) < 0) {

		perror("Cannot send dump request");

		exit(1);

	}

	if (rtnl_dump_filter(rth, ll_remember_index, NULL) < 0) {

		fprintf(stderr, "Dump terminated\n");

		exit(1);

	}

	initialized = 1;

}