Subject: [PATCH v2 2/2] bpf: Add tests for the lpm trie map

From: Daniel Mack <[email-masked]>
Date: Thu, 12 Jan 2017 18:29:22 +0100

From: David Herrmann <[email-masked]>

The first part of this program runs randomized tests against the
lpm-bpf-map. It implements a "Trivial Longest Prefix Match" (tlpm)
based on simple, linear, single linked lists. The implementation
should be pretty straightforward.

Based on tlpm, this inserts randomized data into bpf-lpm-maps and
verifies the trie-based bpf-map implementation behaves the same way
as tlpm.

The second part uses 'real world' IPv4 and IPv6 addresses and tests
the trie with those.

Signed-off-by: David Herrmann <[email-masked]>
Signed-off-by: Daniel Mack <[email-masked]>
---
 tools/testing/selftests/bpf/.gitignore     |   1 +
 tools/testing/selftests/bpf/Makefile       |   4 +-
 tools/testing/selftests/bpf/test_lpm_map.c | 358 +++++++++++++++++++++++++++++
 3 files changed, 361 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/test_lpm_map.c

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 071431b..d3b1c9b 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -1,3 +1,4 @@
 test_verifier
 test_maps
 test_lru_map
+test_lpm_map
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 7a5f245..064a3e5 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -1,8 +1,8 @@
 CFLAGS += -Wall -O2 -I../../../../usr/include
 
-test_objs = test_verifier test_maps test_lru_map
+test_objs = test_verifier test_maps test_lru_map test_lpm_map
 
-TEST_PROGS := test_verifier test_maps test_lru_map test_kmod.sh
+TEST_PROGS := test_verifier test_maps test_lru_map test_lpm_map test_kmod.sh
 TEST_FILES := $(test_objs)
 
 all: $(test_objs)
diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c
new file mode 100644
index 0000000..dd83f0b
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_lpm_map.c
@@ -0,0 +1,358 @@
+/*
+ * Randomized tests for eBPF longest-prefix-match maps
+ *
+ * This program runs randomized tests against the lpm-bpf-map. It implements a
+ * "Trivial Longest Prefix Match" (tlpm) based on simple, linear, singly linked
+ * lists. The implementation should be pretty straightforward.
+ *
+ * Based on tlpm, this inserts randomized data into bpf-lpm-maps and verifies
+ * the trie-based bpf-map implementation behaves the same way as tlpm.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <linux/bpf.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+
+#include "bpf_sys.h"
+#include "bpf_util.h"
+
+struct tlpm_node {
+	struct tlpm_node *next;
+	size_t n_bits;
+	uint8_t key[];
+};
+
+static struct tlpm_node *tlpm_add(struct tlpm_node *list,
+				  const uint8_t *key,
+				  size_t n_bits)
+{
+	struct tlpm_node *node;
+	size_t n;
+
+	/* add new entry with @key/@n_bits to @list and return new head */
+
+	n = (n_bits + 7) / 8;
+	node = malloc(sizeof(*node) + n);
+	assert(node);
+
+	node->next = list;
+	node->n_bits = n_bits;
+	memcpy(node->key, key, n);
+
+	return node;
+}
+
+static void tlpm_clear(struct tlpm_node *list)
+{
+	struct tlpm_node *node;
+
+	/* free all entries in @list */
+
+	while ((node = list)) {
+		list = list->next;
+		free(node);
+	}
+}
+
+static struct tlpm_node *tlpm_match(struct tlpm_node *list,
+				    const uint8_t *key,
+				    size_t n_bits)
+{
+	struct tlpm_node *best = NULL;
+	size_t i;
+
+	/*
+	 * Perform longest prefix-match on @key/@n_bits. That is, iterate all
+	 * entries and match each prefix against @key. Remember the "best"
+	 * entry we find (i.e., the longest prefix that matches) and return it
+	 * to the caller when done.
+	 */
+
+	for ( ; list; list = list->next) {
+		for (i = 0; i < n_bits && i < list->n_bits; ++i) {
+			if ((key[i / 8] & (1 << (7 - i % 8))) !=
+			    (list->key[i / 8] & (1 << (7 - i % 8))))
+				break;
+		}
+
+		if (i >= list->n_bits) {
+			if (!best || i > best->n_bits)
+				best = list;
+		}
+	}
+
+	return best;
+}
+
+static void test_lpm_basic(void)
+{
+	struct tlpm_node *list = NULL, *t1, *t2;
+
+	/* very basic, static tests to verify tlpm works as expected */
+
+	assert(!tlpm_match(list, (uint8_t[]){ 0xff }, 8));
+
+	t1 = list = tlpm_add(list, (uint8_t[]){ 0xff }, 8);
+	assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff }, 8));
+	assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff, 0xff }, 16));
+	assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff, 0x00 }, 16));
+	assert(!tlpm_match(list, (uint8_t[]){ 0x7f }, 8));
+	assert(!tlpm_match(list, (uint8_t[]){ 0xfe }, 8));
+	assert(!tlpm_match(list, (uint8_t[]){ 0xff }, 7));
+
+	t2 = list = tlpm_add(list, (uint8_t[]){ 0xff, 0xff }, 16);
+	assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff }, 8));
+	assert(t2 == tlpm_match(list, (uint8_t[]){ 0xff, 0xff }, 16));
+	assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff, 0xff }, 15));
+	assert(!tlpm_match(list, (uint8_t[]){ 0x7f, 0xff }, 16));
+
+	tlpm_clear(list);
+}
+
+static void test_lpm_order(void)
+{
+	struct tlpm_node *t1, *t2, *l1 = NULL, *l2 = NULL;
+	size_t i, j;
+
+	/*
+	 * Verify the tlpm implementation works correctly regardless of the
+	 * order of entries. Insert a random set of entries into @l1, and copy
+	 * the same data in reverse order into @l2. Then verify a lookup of
+	 * random keys will yield the same result in both sets.
+	 */
+
+	for (i = 0; i < (1 << 12); ++i)
+		l1 = tlpm_add(l1, (uint8_t[]){
+					rand() % 0xff,
+					rand() % 0xff,
+				}, rand() % 16 + 1);
+
+	for (t1 = l1; t1; t1 = t1->next)
+		l2 = tlpm_add(l2, t1->key, t1->n_bits);
+
+	for (i = 0; i < (1 << 8); ++i) {
+		uint8_t key[] = { rand() % 0xff, rand() % 0xff };
+
+		t1 = tlpm_match(l1, key, 16);
+		t2 = tlpm_match(l2, key, 16);
+
+		assert(!t1 == !t2);
+		if (t1) {
+			assert(t1->n_bits == t2->n_bits);
+			for (j = 0; j < t1->n_bits; ++j)
+				assert((t1->key[j / 8] & (1 << (7 - j % 8))) ==
+				       (t2->key[j / 8] & (1 << (7 - j % 8))));
+		}
+	}
+
+	tlpm_clear(l1);
+	tlpm_clear(l2);
+}
+
+static void test_lpm_map(void)
+{
+	size_t i, j, n_matches, n_nodes, n_lookups;
+	struct tlpm_node *t, *list = NULL;
+	struct bpf_lpm_trie_key *key;
+	uint8_t value[8] = {};
+	int r, map;
+
+	/*
+	 * Compare behavior of tlpm vs. bpf-lpm. Create a randomized set of
+	 * prefixes and insert it into both tlpm and bpf-lpm. Then run some
+	 * randomized lookups and verify both maps return the same result.
+	 */
+
+	n_matches = 0;
+	n_nodes = 1 << 8;
+	n_lookups = 1 << 16;
+
+	key = alloca(sizeof(*key) + 4);
+	memset(key, 0, sizeof(*key) + 4);
+
+	map = bpf_map_create(BPF_MAP_TYPE_LPM_TRIE,
+			     sizeof(*key) + 4,
+			     sizeof(value),
+			     4096,
+			     BPF_F_NO_PREALLOC);
+	assert(map >= 0);
+
+	for (i = 0; i < n_nodes; ++i) {
+		value[0] = rand() & 0xff;
+		value[1] = rand() & 0xff;
+		value[2] = rand() & 0xff;
+		value[3] = rand() & 0xff;
+		value[4] = rand() % 33;
+
+		list = tlpm_add(list, value, value[4]);
+
+		key->prefixlen = value[4];
+		memcpy(key->data, value, 4);
+		r = bpf_map_update(map, key, value, 0);
+		assert(!r);
+	}
+
+	for (i = 0; i < n_lookups; ++i) {
+		uint8_t data[] = {
+			rand() % 0xff,
+			rand() % 0xff,
+			rand() % 0xff,
+			rand() % 0xff
+		};
+
+		t = tlpm_match(list, data, 32);
+
+		key->prefixlen = 32;
+		memcpy(key->data, data, 4);
+		r = bpf_map_lookup(map, key, value);
+		assert(!r || errno == ENOENT);
+		assert(!t == !!r);
+
+		if (t) {
+			++n_matches;
+			assert(t->n_bits == value[4]);
+			for (j = 0; j < t->n_bits; ++j)
+				assert((t->key[j / 8] & (1 << (7 - j % 8))) ==
+				       (value[j / 8] & (1 << (7 - j % 8))));
+		}
+	}
+
+	close(map);
+	tlpm_clear(list);
+
+	/*
+	 * With 255 random nodes in the map, we are pretty likely to match
+	 * something on every lookup. For statistics, use this:
+	 *
+	 *     printf("  nodes: %zu\n"
+	 *            "lookups: %zu\n"
+	 *            "matches: %zu\n", n_nodes, n_lookups, n_matches);
+	 */
+}
+
+/* Test the implementation with some 'real world' examples */
+
+static void test_lpm_ipaddr(void)
+{
+	struct bpf_lpm_trie_key *key_ipv4;
+	struct bpf_lpm_trie_key *key_ipv6;
+	size_t key_size_ipv4;
+	size_t key_size_ipv6;
+	int map_fd_ipv4;
+	int map_fd_ipv6;
+	__u64 value;
+
+	key_size_ipv4 = sizeof(*key_ipv4) + sizeof(__u32);
+	key_size_ipv6 = sizeof(*key_ipv6) + sizeof(__u32) * 4;
+	key_ipv4 = alloca(key_size_ipv4);
+	key_ipv6 = alloca(key_size_ipv6);
+
+	map_fd_ipv4 = bpf_map_create(BPF_MAP_TYPE_LPM_TRIE,
+				     key_size_ipv4, sizeof(value),
+				     100, BPF_F_NO_PREALLOC);
+	assert(map_fd_ipv4 >= 0);
+
+	map_fd_ipv6 = bpf_map_create(BPF_MAP_TYPE_LPM_TRIE,
+				     key_size_ipv6, sizeof(value),
+				     100, BPF_F_NO_PREALLOC);
+	assert(map_fd_ipv6 >= 0);
+
+	/* Fill data some IPv4 and IPv6 address ranges */
+	value = 1;
+	key_ipv4->prefixlen = 16;
+	inet_pton(AF_INET, "192.168.0.0", key_ipv4->data);
+	assert(bpf_map_update(map_fd_ipv4, key_ipv4, &value, 0) == 0);
+
+	value = 2;
+	key_ipv4->prefixlen = 24;
+	inet_pton(AF_INET, "192.168.0.0", key_ipv4->data);
+	assert(bpf_map_update(map_fd_ipv4, key_ipv4, &value, 0) == 0);
+
+	value = 3;
+	key_ipv4->prefixlen = 24;
+	inet_pton(AF_INET, "192.168.128.0", key_ipv4->data);
+	assert(bpf_map_update(map_fd_ipv4, key_ipv4, &value, 0) == 0);
+
+	value = 5;
+	key_ipv4->prefixlen = 24;
+	inet_pton(AF_INET, "192.168.1.0", key_ipv4->data);
+	assert(bpf_map_update(map_fd_ipv4, key_ipv4, &value, 0) == 0);
+
+	value = 4;
+	key_ipv4->prefixlen = 23;
+	inet_pton(AF_INET, "192.168.0.0", key_ipv4->data);
+	assert(bpf_map_update(map_fd_ipv4, key_ipv4, &value, 0) == 0);
+
+	value = 0xdeadbeef;
+	key_ipv6->prefixlen = 64;
+	inet_pton(AF_INET6, "2a00:1450:4001:814::200e", key_ipv6->data);
+	assert(bpf_map_update(map_fd_ipv6, key_ipv6, &value, 0) == 0);
+
+	/* Set tprefixlen to maximum for lookups */
+	key_ipv4->prefixlen = 32;
+	key_ipv6->prefixlen = 128;
+
+	/* Test some lookups that should come back with a value */
+	inet_pton(AF_INET, "192.168.128.23", key_ipv4->data);
+	assert(bpf_map_lookup(map_fd_ipv4, key_ipv4, &value) == 0);
+	assert(value == 3);
+
+	inet_pton(AF_INET, "192.168.0.1", key_ipv4->data);
+	assert(bpf_map_lookup(map_fd_ipv4, key_ipv4, &value) == 0);
+	assert(value == 2);
+
+	inet_pton(AF_INET6, "2a00:1450:4001:814::", key_ipv6->data);
+	assert(bpf_map_lookup(map_fd_ipv6, key_ipv6, &value) == 0);
+	assert(value == 0xdeadbeef);
+
+	inet_pton(AF_INET6, "2a00:1450:4001:814::1", key_ipv6->data);
+	assert(bpf_map_lookup(map_fd_ipv6, key_ipv6, &value) == 0);
+	assert(value == 0xdeadbeef);
+
+	/* Test some lookups that should not match any entry */
+	inet_pton(AF_INET, "10.0.0.1", key_ipv4->data);
+	assert(bpf_map_lookup(map_fd_ipv4, key_ipv4, &value) == -1 &&
+	       errno == ENOENT);
+
+	inet_pton(AF_INET, "11.11.11.11", key_ipv4->data);
+	assert(bpf_map_lookup(map_fd_ipv4, key_ipv4, &value) == -1 &&
+	       errno == ENOENT);
+
+	inet_pton(AF_INET6, "2a00:ffff::", key_ipv6->data);
+	assert(bpf_map_lookup(map_fd_ipv6, key_ipv6, &value) == -1 &&
+	       errno == ENOENT);
+
+	close(map_fd_ipv4);
+	close(map_fd_ipv6);
+}
+
+int main(void)
+{
+	struct rlimit limit  = { RLIM_INFINITY, RLIM_INFINITY };
+	int ret;
+
+	/* we want predictable, pseudo random tests */
+	srand(0xf00ba1);
+
+	/* allow unlimited locked memory */
+	ret = setrlimit(RLIMIT_MEMLOCK, &limit);
+	if (ret < 0)
+		perror("Unable to lift memlock rlimit");
+
+	test_lpm_basic();
+	test_lpm_order();
+	test_lpm_map();
+	test_lpm_ipaddr();
+
+	printf("test_lpm: OK\n");
+	return 0;
+}
-- 
2.9.3