[PATCH bpf-next v2 04/13] bpfilter: Add map container

[Dmitrii Banshchikov <me@ubique.spb.ru>]

Introduce common code for an associative container. This common code
will be used for maps of matches, targets and tables. Hash search tables
from libc are used as an index. The supported set of operations is:
find and upsert.

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
---
 net/bpfilter/Makefile                         |  2 +-
 net/bpfilter/map-common.c                     | 50 +++++++++++++++
 net/bpfilter/map-common.h                     | 18 ++++++
 .../testing/selftests/bpf/bpfilter/.gitignore |  2 +
 tools/testing/selftests/bpf/bpfilter/Makefile | 19 ++++++
 .../testing/selftests/bpf/bpfilter/test_map.c | 63 +++++++++++++++++++
 6 files changed, 153 insertions(+), 1 deletion(-)
 create mode 100644 net/bpfilter/map-common.c
 create mode 100644 net/bpfilter/map-common.h
 create mode 100644 tools/testing/selftests/bpf/bpfilter/.gitignore
 create mode 100644 tools/testing/selftests/bpf/bpfilter/Makefile
 create mode 100644 tools/testing/selftests/bpf/bpfilter/test_map.c

diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile
index cdac82b8c53a..1809759d08c4 100644
--- a/net/bpfilter/Makefile
+++ b/net/bpfilter/Makefile
@@ -4,7 +4,7 @@
 #
 
 userprogs := bpfilter_umh
-bpfilter_umh-objs := main.o
+bpfilter_umh-objs := main.o map-common.o
 userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi
 
 ifeq ($(CONFIG_BPFILTER_UMH), y)
diff --git a/net/bpfilter/map-common.c b/net/bpfilter/map-common.c
new file mode 100644
index 000000000000..f933929a3909
--- /dev/null
+++ b/net/bpfilter/map-common.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021 Telegram FZ-LLC
+ */
+
+#include "map-common.h"
+
+#include <linux/err.h>
+
+#include <errno.h>
+#include <string.h>
+
+int create_map(struct hsearch_data *htab, size_t nelem)
+{
+	memset(htab, 0, sizeof(*htab));
+	if (!hcreate_r(nelem, htab))
+		return -errno;
+
+	return 0;
+}
+
+void *map_find(struct hsearch_data *htab, const char *key)
+{
+	const ENTRY needle = { .key = (char *)key };
+	ENTRY *found;
+
+	if (!hsearch_r(needle, FIND, &found, htab))
+		return ERR_PTR(-ENOENT);
+
+	return found->data;
+}
+
+int map_upsert(struct hsearch_data *htab, const char *key, void *value)
+{
+	const ENTRY needle = { .key = (char *)key, .data = value };
+	ENTRY *found;
+
+	if (!hsearch_r(needle, ENTER, &found, htab))
+		return -errno;
+
+	found->key = (char *)key;
+	found->data = value;
+
+	return 0;
+}
+
+void free_map(struct hsearch_data *htab)
+{
+	hdestroy_r(htab);
+}
diff --git a/net/bpfilter/map-common.h b/net/bpfilter/map-common.h
new file mode 100644
index 000000000000..236ba906828e
--- /dev/null
+++ b/net/bpfilter/map-common.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Telegram FZ-LLC
+ */
+
+#ifndef NET_BPFILTER_MAP_COMMON_H
+#define NET_BPFILTER_MAP_COMMON_H
+
+#define _GNU_SOURCE
+
+#include <search.h>
+
+int create_map(struct hsearch_data *htab, size_t nelem);
+void *map_find(struct hsearch_data *htab, const char *key);
+int map_upsert(struct hsearch_data *htab, const char *key, void *value);
+void free_map(struct hsearch_data *htab);
+
+#endif // NET_BPFILTER_MAP_COMMON_H
diff --git a/tools/testing/selftests/bpf/bpfilter/.gitignore b/tools/testing/selftests/bpf/bpfilter/.gitignore
new file mode 100644
index 000000000000..983fd06cbefa
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+test_map
diff --git a/tools/testing/selftests/bpf/bpfilter/Makefile b/tools/testing/selftests/bpf/bpfilter/Makefile
new file mode 100644
index 000000000000..c262aad8c2a4
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/Makefile
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+
+top_srcdir = ../../../../..
+TOOLSDIR := $(abspath ../../../../)
+TOOLSINCDIR := $(TOOLSDIR)/include
+APIDIR := $(TOOLSINCDIR)/uapi
+BPFILTERSRCDIR := $(top_srcdir)/net/bpfilter
+
+CFLAGS += -Wall -g -pthread -I$(TOOLSINCDIR) -I$(APIDIR) -I$(BPFILTERSRCDIR)
+
+TEST_GEN_PROGS += test_map
+
+KSFT_KHDR_INSTALL := 1
+
+include ../../lib.mk
+
+BPFILTER_MAP_SRCS := $(BPFILTERSRCDIR)/map-common.c
+
+$(OUTPUT)/test_map: test_map.c $(BPFILTER_MAP_SRCS)
diff --git a/tools/testing/selftests/bpf/bpfilter/test_map.c b/tools/testing/selftests/bpf/bpfilter/test_map.c
new file mode 100644
index 000000000000..7ed737b78816
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/test_map.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "map-common.h"
+
+#include <linux/err.h>
+
+#include "../../kselftest_harness.h"
+
+FIXTURE(test_map)
+{
+	struct hsearch_data map;
+	const char *key;
+	void *expected;
+	void *actual;
+};
+
+FIXTURE_SETUP(test_map)
+{
+	const int max_nelements = 100;
+
+	create_map(&self->map, max_nelements);
+	self->key = "key";
+	self->expected = "expected";
+	self->actual = "actual";
+}
+
+FIXTURE_TEARDOWN(test_map)
+{
+	free_map(&self->map);
+}
+
+TEST_F(test_map, upsert_and_find)
+{
+	void *found;
+
+	found = map_find(&self->map, self->key);
+	ASSERT_TRUE(IS_ERR(found))
+	ASSERT_EQ(-ENOENT, PTR_ERR(found))
+
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->actual));
+
+	found = map_find(&self->map, self->key);
+
+	ASSERT_FALSE(IS_ERR(found));
+	ASSERT_STREQ(self->actual, found);
+}
+
+TEST_F(test_map, update)
+{
+	void *found;
+
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->actual));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+
+	found = map_find(&self->map, self->key);
+
+	ASSERT_FALSE(IS_ERR(found));
+	ASSERT_STREQ(self->expected, found);
+}
+
+TEST_HARNESS_MAIN
-- 
2.25.1