@@ -1,136 +1,155 @@
-/*
- * Copyright (c) 1996-1999 by Internet Software Consortium.
- *
- * 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
- * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
- * CONSORTIUM 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.
- */
+/* Convert IPv4/IPv6 addresses from binary to text form.
+ Copyright (C) 1996-2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
-#include <sys/param.h>
-#include <sys/types.h>
-#include <sys/socket.h>
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
-#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
-
#include <errno.h>
-#include <stdio.h>
#include <string.h>
+#include <_itoa.h>
-#ifdef SPRINTF_CHAR
-# define SPRINTF(x) strlen (sprintf /**/ x)
-#else
-# define SPRINTF(x) ((size_t) sprintf x)
-#endif
-
-/*
- * WARNING: Don't even consider trying to compile this on a system where
- * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
- */
-
-static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size);
-static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size);
-
-/* char *
- * __inet_ntop(af, src, dst, size)
- * convert a network format address to presentation format.
- * return:
- * pointer to presentation format address (`dst'), or NULL (see errno).
- * author:
- * Paul Vixie, 1996.
- */
-const char *
-__inet_ntop (int af, const void *src, char *dst, socklen_t size)
+static inline char *
+put_uint8 (uint8_t word, char *tp)
{
- switch (af)
+ int s = 1;
+ if (word >= 10)
{
- case AF_INET:
- return (inet_ntop4 (src, dst, size));
- case AF_INET6:
- return (inet_ntop6 (src, dst, size));
- default:
- __set_errno (EAFNOSUPPORT);
- return (NULL);
+ if (word >= 100)
+ {
+ tp[2] = '0' + word % 10;
+ word /= 10;
+ s += 1;
+ }
+
+ tp[1] = '0' + word % 10;
+ word /= 10;
+ s += 1;
}
- /* NOTREACHED */
+ *tp = '0' + word % 10;
+ return tp + s;
}
-libc_hidden_def (__inet_ntop)
-weak_alias (__inet_ntop, inet_ntop)
-/* const char *
- * inet_ntop4(src, dst, size)
- * format an IPv4 address
- * return:
- * `dst' (as a const)
- * notes:
- * (1) uses no statics
- * (2) takes a u_char* not an in_addr as input
- * author:
- * Paul Vixie, 1996.
- */
-static const char *
-inet_ntop4 (const u_char *src, char *dst, socklen_t size)
+static inline char *
+put_uint16 (uint16_t word, char *tp)
{
- static const char fmt[] = "%u.%u.%u.%u";
- char tmp[sizeof "255.255.255.255"];
+ if (word >= 0x1000)
+ *tp++ = _itoa_lower_digits[(word >> 12) & 0xf];
+ if (word >= 0x100)
+ *tp++ = _itoa_lower_digits[(word >> 8) & 0xf];
+ if (word >= 0x10)
+ *tp++ = _itoa_lower_digits[(word >> 4) & 0xf];
+ *tp++ = _itoa_lower_digits[word & 0xf];
+ return tp;
+}
- if (SPRINTF ((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
+static __always_inline char *
+inet_ntop4_format (const uint8_t *src, char *dst)
+{
+ dst = put_uint8 (src[0], dst);
+ *(dst++) = '.';
+ dst = put_uint8 (src[1], dst);
+ *(dst++) = '.';
+ dst = put_uint8 (src[2], dst);
+ *(dst++) = '.';
+ dst = put_uint8 (src[3], dst);
+ *dst++ = '\0';
+ return dst;
+}
+
+static __always_inline const char *
+inet_ntop4 (const uint8_t *src, char *dst, socklen_t size)
+{
+ if (size >= INET_ADDRSTRLEN)
+ {
+ inet_ntop4_format (src, dst);
+ return dst;
+ }
+
+ char tmp[INET_ADDRSTRLEN];
+ char *tp = inet_ntop4_format (src, tmp);
+ socklen_t tmp_s = tp - tmp;
+ if (tmp_s > size)
{
__set_errno (ENOSPC);
- return (NULL);
+ return NULL;
}
- return strcpy (dst, tmp);
+ return memcpy (dst, tmp, tmp_s);
}
-/* const char *
- * inet_ntop6(src, dst, size)
- * convert IPv6 binary address into presentation (printable) format
- * author:
- * Paul Vixie, 1996.
- */
-static const char *
-inet_ntop6 (const u_char *src, char *dst, socklen_t size)
+struct best_t
{
- /*
- * Note that int32_t and int16_t need only be "at least" large enough
- * to contain a value of the specified size. On some systems, like
- * Crays, there is no such thing as an integer variable with 16 bits.
- * Keep this in mind if you think this function should have been coded
- * to use pointer overlays. All the world's not a VAX.
- */
- char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
- struct
- {
- int base, len;
- } best, cur;
- u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
- int i;
+ int base;
+ int len;
+};
- /*
- * Preprocess:
- * Copy the input (bytewise) array into a wordwise array.
- * Find the longest run of 0x00's in src[] for :: shorthanding.
- */
- memset (words, '\0', sizeof words);
- for (i = 0; i < NS_IN6ADDRSZ; i += 2)
- words[i / 2] = (src[i] << 8) | src[i + 1];
- best.base = -1;
- cur.base = -1;
- best.len = 0;
- cur.len = 0;
- for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
+static inline uint16_t
+in6_addr_addr16 (const struct in6_addr *src, int idx)
+{
+ const struct { uint16_t x; } __attribute__((__packed__)) *pptr =
+ (typeof(pptr))(&src->s6_addr16[idx]);
+ return ntohs (pptr->x);
+}
+
+static __always_inline char *
+inet_ntop6_format (const struct in6_addr *src, struct best_t best, char *dst)
+{
+ char *tp = dst;
+ for (int i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
{
- if (words[i] == 0)
+ /* Are we inside the best run of 0x00's? */
+ if (best.base != -1 && i >= best.base && i < (best.base + best.len))
+ {
+ if (i == best.base)
+ *tp++ = ':';
+ continue;
+ }
+ /* Are we following an initial run of 0x00s or any real hex? */
+ if (i != 0)
+ *tp++ = ':';
+ /* Is this address an encapsulated IPv4? */
+ if (i == 6 && best.base == 0
+ && (best.len == 6 || (best.len == 5
+ && in6_addr_addr16 (src, 5) == 0xffff)))
+ {
+ if (!inet_ntop4 (src->s6_addr + 12, tp,
+ INET6_ADDRSTRLEN - (tp - dst)))
+ return NULL;
+ tp += strlen (tp);
+ break;
+ }
+ tp = put_uint16 (in6_addr_addr16 (src, i), tp);
+ }
+ /* Was it a trailing run of 0x00's? */
+ if (best.base != -1 && (best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ))
+ *tp++ = ':';
+ *tp++ = '\0';
+
+ return tp;
+}
+
+static inline const char *
+inet_ntop6 (const struct in6_addr *src, char *dst, socklen_t size)
+{
+ struct best_t best = { -1, 0 }, cur = { -1, 0 };
+
+ /* ind the longest run of 0x00's in src[] for :: shorthanding. */
+ for (int i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
+ {
+ if (in6_addr_addr16 (src, i) == 0)
{
if (cur.base == -1)
cur.base = i, cur.len = 1;
@@ -155,45 +174,37 @@ inet_ntop6 (const u_char *src, char *dst, socklen_t size)
if (best.base != -1 && best.len < 2)
best.base = -1;
- /*
- * Format the result.
- */
- tp = tmp;
- for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
+ if (size >= INET6_ADDRSTRLEN)
{
- /* Are we inside the best run of 0x00's? */
- if (best.base != -1 && i >= best.base && i < (best.base + best.len))
- {
- if (i == best.base)
- *tp++ = ':';
- continue;
- }
- /* Are we following an initial run of 0x00s or any real hex? */
- if (i != 0)
- *tp++ = ':';
- /* Is this address an encapsulated IPv4? */
- if (i == 6 && best.base == 0
- && (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
- {
- if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))
- return (NULL);
- tp += strlen (tp);
- break;
- }
- tp += SPRINTF ((tp, "%x", words[i]));
+ inet_ntop6_format (src, best, dst);
+ return dst;
}
- /* Was it a trailing run of 0x00's? */
- if (best.base != -1 && (best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ))
- *tp++ = ':';
- *tp++ = '\0';
- /*
- * Check for overflow, copy, and we're done.
- */
- if ((socklen_t) (tp - tmp) > size)
+ char tmp[INET6_ADDRSTRLEN];
+ char *tp = inet_ntop6_format (src, best, tmp);
+
+ socklen_t tmp_s = tp - tmp;
+ if (tmp_s > size)
{
__set_errno (ENOSPC);
return (NULL);
}
- return strcpy (dst, tmp);
+ return memcpy (dst, tmp, tmp_s);
}
+
+const char *
+__inet_ntop (int af, const void *src, char *dst, socklen_t size)
+{
+ switch (af)
+ {
+ case AF_INET:
+ return (inet_ntop4 (src, dst, size));
+ case AF_INET6:
+ return (inet_ntop6 (src, dst, size));
+ default:
+ __set_errno (EAFNOSUPPORT);
+ return (NULL);
+ }
+}
+libc_hidden_def (__inet_ntop)
+weak_alias (__inet_ntop, inet_ntop)
The benchtests/inet_ntop_ipv4 and benchtests/inet_ntop_ipv6 profile shows that most of time is spent in costly sprint operations: $ perf record ./benchtests/bench-inet_ntop_ipv4 && perf report --stdio [...] 38.53% bench-inet_ntop libc.so [.] __printf_buffer 18.69% bench-inet_ntop libc.so [.] __printf_buffer_write 11.01% bench-inet_ntop libc.so [.] _itoa_word 8.02% bench-inet_ntop bench-inet_ntop_ipv4 [.] bench_start 6.99% bench-inet_ntop libc.so [.] __memmove_avx_unaligned_erms 3.86% bench-inet_ntop libc.so [.] __strchrnul_avx2 2.82% bench-inet_ntop libc.so [.] __strcpy_avx2 1.90% bench-inet_ntop libc.so [.] inet_ntop4 1.78% bench-inet_ntop libc.so [.] __vsprintf_internal 1.55% bench-inet_ntop libc.so [.] __sprintf_chk 1.18% bench-inet_ntop libc.so [.] __GI___inet_ntop $ perf record ./benchtests/bench-inet_ntop_ipv6 && perf report --stdio 35.44% bench-inet_ntop libc.so [.] __printf_buffer 14.35% bench-inet_ntop libc.so [.] __printf_buffer_write 10.27% bench-inet_ntop libc.so [.] __GI___inet_ntop 7.93% bench-inet_ntop libc.so [.] _itoa_word 7.00% bench-inet_ntop libc.so [.] __sprintf_chk 6.20% bench-inet_ntop libc.so [.] __vsprintf_internal 5.26% bench-inet_ntop libc.so [.] __strchrnul_avx2 5.05% bench-inet_ntop bench-inet_ntop_ipv6 [.] bench_start 3.70% bench-inet_ntop libc.so [.] __memmove_avx_unaligned_erms 2.11% bench-inet_ntop libc.so [.] __printf_buffer_done A new implementation is used instead: * The printf usage is replaced with an expanded function that prints either an IPv4 octet or an IPv6 quartet; * The strcpy is replaced with a memcpy (since ABIs usually tends to optimize the latter); * For IPv6, the '::' shorthanding is done in-place instead of using a temporary buffer. * An temporary buffer is used iff the size if larger than INET_ADDRSTRLEN/INET6_ADDRSTRLEN. * Inline is used for both inet_ntop4 and inet_ntop6, The code is significand rewrote, so I take this requires a new license. The performance results on aarch64 Neoverse1 with gcc 14.2.1: * master aarch64-linux-gnu-master$ ./benchtests/bench-inet_ntop_ipv4 "inet_ntop_ipv4": { "workload-ipv4-random": { "duration": 1.43067e+09, "iterations": 8e+06, "reciprocal-throughput": 178.572, "latency": 179.096, "max-throughput": 5.59997e+06, "min-throughput": 5.58359e+06 } aarch64-linux-gnu-master$ ./benchtests/bench-inet_ntop_ipv6 "inet_ntop_ipv6": { "workload-ipv6-random": { "duration": 1.68539e+09, "iterations": 4e+06, "reciprocal-throughput": 421.307, "latency": 421.388, "max-throughput": 2.37357e+06, "min-throughput": 2.37311e+06 } } * patched aarch64-linux-gnu$ ./benchtests/bench-inet_ntop_ipv4 "inet_ntop_ipv4": { "workload-ipv4-random": { "duration": 1.06133e+09, "iterations": 5.6e+07, "reciprocal-throughput": 18.8482, "latency": 19.0565, "max-throughput": 5.30555e+07, "min-throughput": 5.24755e+07 } } aarch64-linux-gnu$ ./benchtests/bench-inet_ntop_ipv6 "inet_ntop_ipv6": { "workload-ipv6-random": { "duration": 1.01246e+09, "iterations": 2.4e+07, "reciprocal-throughput": 42.5576, "latency": 41.8139, "max-throughput": 2.34976e+07, "min-throughput": 2.39155e+07 } } Checked on aarch64-linux-gnu and x86_64-linux-gnu. --- resolv/inet_ntop.c | 301 +++++++++++++++++++++++---------------------- 1 file changed, 156 insertions(+), 145 deletions(-)