1 files changed, 405 insertions, 0 deletions
diff --git a/lib/ll_map.c b/lib/ll_map.c
new file mode 100644
index 0000000..8970c20
--- /dev/null
+++ b/lib/ll_map.c
@@ -0,0 +1,405 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * ll_map.c
+ *
+ * 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;
+}