inet_ntop but faster

lib/compiler.h

@@ -33,6 +33,9 @@ extern "C" {
 #endif
 # define _CONSTRUCTOR(x)  constructor(x)
 # define _DEPRECATED(x) deprecated(x)
+# if __has_builtin(assume)
+#  define assume(x) __builtin_assume(x)
+# endif
 #elif defined(__GNUC__)
 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 9)
 #  define _RET_NONNULL    , returns_nonnull
@@ -44,12 +47,28 @@ extern "C" {
 #endif
 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
 #  define _DEPRECATED(x) deprecated(x)
+#  define assume(x) do { if (!(x)) __builtin_unreachable(); } while (0)
+#endif
+#if __GNUC__ < 5
+#  define __has_attribute(x) 0
 #endif
 #if __GNUC__ >= 7
 #  define _FALLTHROUGH __attribute__((fallthrough));
 #endif
 #endif
 
+#if __has_attribute(hot)
+#  define _OPTIMIZE_HOT __attribute__((hot))
+#else
+#  define _OPTIMIZE_HOT
+#endif
+#if __has_attribute(optimize)
+#  define _OPTIMIZE_O3 __attribute__((optimize("3")))
+#else
+#  define _OPTIMIZE_O3
+#endif
+#define OPTIMIZE _OPTIMIZE_O3 _OPTIMIZE_HOT
+
 #if !defined(__GNUC__)
 #error module code needs GCC visibility extensions
 #elif __GNUC__ < 4
@@ -85,6 +104,9 @@ extern "C" {
 #ifndef _DEPRECATED
 #define _DEPRECATED(x) deprecated
 #endif
+#ifndef assume
+#define assume(x)
+#endif
 
 /* pure = function does not modify memory & return value is the same if
  * memory hasn't changed (=> allows compiler to optimize)

lib/ntop.c

@@ -0,0 +1,174 @@
+/*
+ * optimized ntop, about 10x faster than libc versions [as of 2019]
+ *
+ * Copyright (c) 2019  David Lamparter, for NetDEF, Inc.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include "compiler.h"
+
+#define pos (*posx)
+
+static inline void putbyte(uint8_t bytex, char **posx)
+	__attribute__((always_inline)) OPTIMIZE;
+
+static inline void putbyte(uint8_t bytex, char **posx)
+{
+	bool zero = false;
+	int byte = bytex, tmp, a, b;
+
+	if ((tmp = byte - 200) >= 0) {
+		*pos++ = '2';
+		zero = true;
+		byte = tmp;
+	} else if ((tmp = byte - 100) >= 0) {
+		*pos++ = '1';
+		zero = true;
+		byte = tmp;
+	}
+
+	/* make sure the compiler knows the value range of "byte" */
+	assume(byte < 100 && byte >= 0);
+
+	b = byte % 10;
+	a = byte / 10;
+	if (a || zero) {
+		*pos++ = '0' + a;
+		*pos++ = '0' + b;
+	} else
+		*pos++ = '0' + b;
+}
+
+static inline void puthex(uint16_t word, char **posx)
+	__attribute__((always_inline)) OPTIMIZE;
+
+static inline void puthex(uint16_t word, char **posx)
+{
+	const char *digits = "0123456789abcdef";
+	if (word >= 0x1000)
+		*pos++ = digits[(word >> 12) & 0xf];
+	if (word >= 0x100)
+		*pos++ = digits[(word >> 8) & 0xf];
+	if (word >= 0x10)
+		*pos++ = digits[(word >> 4) & 0xf];
+	*pos++ = digits[word & 0xf];
+}
+
+#undef pos
+
+const char *frr_inet_ntop(int af, const void * restrict src,
+			  char * restrict dst, socklen_t size)
+	__attribute__((flatten)) DSO_SELF OPTIMIZE;
+
+const char *frr_inet_ntop(int af, const void * restrict src,
+			  char * restrict dst, socklen_t size)
+{
+	const uint8_t *b = src;
+	/* 8 * "abcd:" for IPv6
+	 * note: the IPv4-embedded IPv6 syntax is only used for ::A.B.C.D,
+	 * which isn't longer than 40 chars either.  even with ::ffff:A.B.C.D
+	 * it's shorter.
+	 */
+	char buf[8 * 5], *o = buf;
+	size_t best = 0, bestlen = 0, curlen = 0, i;
+
+	switch (af) {
+	case AF_INET:
+inet4:
+		putbyte(b[0], &o);
+		*o++ = '.';
+		putbyte(b[1], &o);
+		*o++ = '.';
+		putbyte(b[2], &o);
+		*o++ = '.';
+		putbyte(b[3], &o);
+		*o++ = '\0';
+		break;
+	case AF_INET6:
+		for (i = 0; i < 8; i++) {
+			if (b[i * 2] || b[i * 2 + 1]) {
+				if (curlen && curlen > bestlen) {
+					best = i - curlen;
+					bestlen = curlen;
+				}
+				curlen = 0;
+				continue;
+			}
+			curlen++;
+		}
+		if (curlen && curlen > bestlen) {
+			best = i - curlen;
+			bestlen = curlen;
+		}
+		/* do we want ::ffff:A.B.C.D? */
+		if (best == 0 && bestlen == 6) {
+			*o++ = ':';
+			*o++ = ':';
+			b += 12;
+			goto inet4;
+		}
+		if (bestlen == 1)
+			bestlen = 0;
+
+		for (i = 0; i < 8; i++) {
+			if (bestlen && i == best) {
+				if (i == 0)
+					*o++ = ':';
+				*o++ = ':';
+				continue;
+			}
+			if (i > best && i < best + bestlen) {
+				continue;
+			}
+			puthex((b[i * 2] << 8) | b[i * 2 + 1], &o);
+
+			if (i < 7)
+				*o++ = ':';
+		}
+		*o++ = '\0';
+		break;
+	default:
+		return NULL;
+	}
+
+	i = o - buf;
+	if (i > size)
+		return NULL;
+	/* compiler might inline memcpy if it knows the length is short,
+	 * although neither gcc nor clang actually do this currently [2019]
+	 */
+	assume(i <= 8 * 5);
+	memcpy(dst, buf, i);
+	return dst;
+}
+
+#ifndef INET_NTOP_NO_OVERRIDE
+/* we want to override libc inet_ntop, but make sure it shows up in backtraces
+ * as frr_inet_ntop (to avoid confusion while debugging)
+ */
+const char *inet_ntop(int af, const void *src, char *dst, socklen_t size)
+	__attribute__((alias ("frr_inet_ntop"))) DSO_SELF;
+#endif

lib/subdir.am

@@ -56,6 +56,7 @@ lib_libfrr_la_SOURCES = \
 	lib/northbound.c \
 	lib/northbound_cli.c \
 	lib/northbound_db.c \
+	lib/ntop.c \
 	lib/openbsd-tree.c \
 	lib/pid_output.c \
 	lib/plist.c \

tests/.gitignore

@@ -30,6 +30,7 @@
 /lib/test_idalloc
 /lib/test_memory
 /lib/test_nexthop_iter
+/lib/test_ntop
 /lib/test_printfrr
 /lib/test_privs
 /lib/test_ringbuf

tests/lib/test_ntop.c

@@ -0,0 +1,87 @@
+/*
+ * frr_inet_ntop() unit test
+ * Copyright (C) 2019  David Lamparter
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <assert.h>
+
+#include "tests/helpers/c/prng.h"
+
+/* NB: libfrr is NOT linked for this unit test! */
+
+#define INET_NTOP_NO_OVERRIDE
+#include "lib/ntop.c"
+
+int main(int argc, char **argv)
+{
+	size_t i, j, k, l;
+	struct in_addr i4;
+	struct in6_addr i6, i6check;
+	char buf1[64], buf2[64];
+	const char *rv;
+	struct prng *prng;
+
+	prng = prng_new(0);
+	/* IPv4 */
+	for (i = 0; i < 1000; i++) {
+		i4.s_addr = prng_rand(prng);
+		assert(frr_inet_ntop(AF_INET, &i4, buf1, sizeof(buf1)));
+		assert(inet_ntop(AF_INET, &i4, buf2, sizeof(buf2)));
+		assert(!strcmp(buf1, buf2));
+	}
+
+	/* check size limit */
+	for (i = 0; i < sizeof(buf1); i++) {
+		memset(buf2, 0xcc, sizeof(buf2));
+		rv = frr_inet_ntop(AF_INET, &i4, buf2, i);
+		if (i < strlen(buf1) + 1)
+			assert(!rv);
+		else
+			assert(rv && !strcmp(buf1, buf2));
+	}
+
+	/* IPv6 */
+	for (i = 0; i < 10000; i++) {
+		uint16_t *i6w = (uint16_t *)&i6;
+		for (j = 0; j < 8; j++)
+			i6w[j] = prng_rand(prng);
+
+		/* clear some words */
+		l = prng_rand(prng) & 7;
+		for (j = 0; j < l; j++) {
+			uint32_t num = __builtin_ctz(prng_rand(prng));
+			uint32_t where = prng_rand(prng) & 7;
+
+			for (k = where; k < where + num && k < 8; k++)
+				i6w[k] = 0;
+		}
+
+		assert(frr_inet_ntop(AF_INET6, &i6, buf1, sizeof(buf1)));
+		assert(inet_ntop(AF_INET6, &i6, buf2, sizeof(buf2)));
+		if (strcmp(buf1, buf2))
+			printf("%-40s (FRR) != (SYS) %-40s\n", buf1, buf2);
+
+		assert(inet_pton(AF_INET6, buf1, &i6check));
+		assert(!memcmp(&i6, &i6check, sizeof(i6)));
+		assert(strlen(buf1) <= strlen(buf2));
+	}
+	return 0;
+}

tests/lib/test_ntop.py

@@ -0,0 +1,6 @@
+import frrtest
+
+class TestNtop(frrtest.TestMultiOut):
+    program = './test_ntop'
+
+TestNtop.exit_cleanly()

tests/subdir.am

@@ -56,6 +56,7 @@ check_PROGRAMS = \
 	tests/lib/test_idalloc \
 	tests/lib/test_memory \
 	tests/lib/test_nexthop_iter \
+	tests/lib/test_ntop \
 	tests/lib/test_printfrr \
 	tests/lib/test_privs \
 	tests/lib/test_ringbuf \
@@ -233,6 +234,10 @@ tests_lib_test_nexthop_iter_CFLAGS = $(TESTS_CFLAGS)
 tests_lib_test_nexthop_iter_CPPFLAGS = $(TESTS_CPPFLAGS)
 tests_lib_test_nexthop_iter_LDADD = $(ALL_TESTS_LDADD)
 tests_lib_test_nexthop_iter_SOURCES = tests/lib/test_nexthop_iter.c tests/helpers/c/prng.c
+tests_lib_test_ntop_CFLAGS = $(TESTS_CFLAGS)
+tests_lib_test_ntop_CPPFLAGS = $(TESTS_CPPFLAGS)
+tests_lib_test_ntop_LDADD = # none
+tests_lib_test_ntop_SOURCES = tests/lib/test_ntop.c tests/helpers/c/prng.c
 tests_lib_test_printfrr_CFLAGS = $(TESTS_CFLAGS)
 tests_lib_test_printfrr_CPPFLAGS = $(TESTS_CPPFLAGS)
 tests_lib_test_printfrr_LDADD = $(ALL_TESTS_LDADD)
@@ -324,6 +329,7 @@ EXTRA_DIST += \
 	tests/lib/northbound/test_oper_data.refout \
 	tests/lib/test_atomlist.py \
 	tests/lib/test_nexthop_iter.py \
+	tests/lib/test_ntop.py \
 	tests/lib/test_printfrr.py \
 	tests/lib/test_ringbuf.py \
 	tests/lib/test_srcdest_table.py \