/*

 * 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"

#include "utils.h"

struct ll_cache {

	struct hlist_node idx_hash;

	struct hlist_node name_hash;

	unsigned	flags;

	unsigned 	index;

	unsigned short	type;

	struct list_head altnames_list;

	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 (strcmp(im->name, name) == 0)

			return im;

	}

	return NULL;

}

static struct ll_cache *ll_entry_create(struct ifinfomsg *ifi,

					const char *ifname,

					struct ll_cache *parent_im)

{

	struct ll_cache *im;

	unsigned int h;

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

	if (!im)

		return NULL;

	im->index = ifi->ifi_index;

	strcpy(im->name, ifname);

	im->type = ifi->ifi_type;

	im->flags = ifi->ifi_flags;

	if (parent_im) {

		list_add_tail(&im->altnames_list, &parent_im->altnames_list);

	} else {

		/* This is parent, insert to index hash. */

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

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

		INIT_LIST_HEAD(&im->altnames_list);

	}

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

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

	return im;

}

static void ll_entry_destroy(struct ll_cache *im, bool im_is_parent)

{

	hlist_del(&im->name_hash);

	if (im_is_parent)

		hlist_del(&im->idx_hash);

	else

		list_del(&im->altnames_list);

	free(im);

}

static void ll_entry_update(struct ll_cache *im, struct ifinfomsg *ifi,

			    const char *ifname)

{

	unsigned int h;

	im->flags = ifi->ifi_flags;

	if (!strcmp(im->name, ifname))

		return;

	hlist_del(&im->name_hash);

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

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

}

static void ll_altname_entries_create(struct ll_cache *parent_im,

				      struct ifinfomsg *ifi, struct rtattr **tb)

{

	struct rtattr *i, *proplist = tb[IFLA_PROP_LIST];

	int rem;

	if (!proplist)

		return;

	rem = RTA_PAYLOAD(proplist);

	for (i = RTA_DATA(proplist); RTA_OK(i, rem);

	     i = RTA_NEXT(i, rem)) {

		if (i->rta_type != IFLA_ALT_IFNAME)

			continue;

		ll_entry_create(ifi, rta_getattr_str(i), parent_im);

	}

}

static void ll_altname_entries_destroy(struct ll_cache *parent_im)

{

	struct ll_cache *im, *tmp;

	list_for_each_entry_safe(im, tmp, &parent_im->altnames_list,

				 altnames_list)

		ll_entry_destroy(im, false);

}

static void ll_altname_entries_update(struct ll_cache *parent_im,

				      struct ifinfomsg *ifi, struct rtattr **tb)

{

	struct rtattr *i, *proplist = tb[IFLA_PROP_LIST];

	struct ll_cache *im;

	int rem;

	if (!proplist) {

		ll_altname_entries_destroy(parent_im);

		return;

	}

	/* Simply compare the altname list with the cached one

	 * and if it does not fit 1:1, recreate the cached list

	 * from scratch.

	 */

	im = list_first_entry(&parent_im->altnames_list, typeof(*im),

			      altnames_list);

	rem = RTA_PAYLOAD(proplist);

	for (i = RTA_DATA(proplist); RTA_OK(i, rem);

	     i = RTA_NEXT(i, rem)) {

		if (i->rta_type != IFLA_ALT_IFNAME)

			continue;

		if (!im || strcmp(rta_getattr_str(i), im->name))

			goto recreate_altname_entries;

		im = list_next_entry(im, altnames_list);

	}

	if (list_next_entry(im, altnames_list))

		goto recreate_altname_entries;

	return;

recreate_altname_entries:

	ll_altname_entries_destroy(parent_im);

	ll_altname_entries_create(parent_im, ifi, tb);

}

static void ll_entries_create(struct ifinfomsg *ifi, struct rtattr **tb)

{

	struct ll_cache *parent_im;

	if (!tb[IFLA_IFNAME])

		return;

	parent_im = ll_entry_create(ifi, rta_getattr_str(tb[IFLA_IFNAME]),

				    NULL);

	if (!parent_im)

		return;

	ll_altname_entries_create(parent_im, ifi, tb);

}

static void ll_entries_destroy(struct ll_cache *parent_im)

{

	ll_altname_entries_destroy(parent_im);

	ll_entry_destroy(parent_im, true);

}

static void ll_entries_update(struct ll_cache *parent_im,

			      struct ifinfomsg *ifi, struct rtattr **tb)

{

	if (tb[IFLA_IFNAME])

		ll_entry_update(parent_im, ifi,

				rta_getattr_str(tb[IFLA_IFNAME]));

	ll_altname_entries_update(parent_im, ifi, tb);

}

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

{

	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)

			ll_entries_destroy(im);

		return 0;

	}

	parse_rtattr_flags(tb, IFLA_MAX, IFLA_RTA(ifi),

			   IFLA_PAYLOAD(n), NLA_F_NESTED);

	if (im)

		ll_entries_update(im, ifi, tb);

	else

		ll_entries_create(ifi, tb);

	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),

			  !check_ifname(name) ? IFLA_IFNAME : IFLA_ALT_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;

}