lib: add optimized inet_ntop()

This commit is brought to you by: "Manuel - Gas Gas Gas" (Initial D)

Signed-off-by: David Lamparter <equinox@diac24.net>

2 files changed, 173 insertions, 0 deletions

diff --git a/lib/ntop.c b/lib/ntop.c
new file mode 100644
index 0000000000..5500f988e0
--- /dev/null
+++ b/lib/ntop.c
@@ -0,0 +1,172 @@
+/*
+ * 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;
+}
+
+/* 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;
diff --git a/lib/subdir.am b/lib/subdir.am
index 50ff1feecc..4e6adced74 100644
--- a/lib/subdir.am
+++ b/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 \