[PATCH 04/13] resolv: Add the __ns_samebinaryname function
Siddhesh Poyarekar
siddhesh@gotplt.org
Thu Aug 18 16:46:35 GMT 2022
On 2022-08-10 05:30, Florian Weimer via Libc-alpha wrote:
> ---
> include/arpa/nameser.h | 6 ++++
> resolv/Makefile | 5 +++
> resolv/ns_samebinaryname.c | 55 ++++++++++++++++++++++++++++++
> resolv/tst-ns_samebinaryname.c | 62 ++++++++++++++++++++++++++++++++++
> 4 files changed, 128 insertions(+)
> create mode 100644 resolv/ns_samebinaryname.c
> create mode 100644 resolv/tst-ns_samebinaryname.c
OK, but like 3/13, it would be nice to document in the commit log why
this function is needed.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
>
> diff --git a/include/arpa/nameser.h b/include/arpa/nameser.h
> index 53f1dbc7c3..bb1dede187 100644
> --- a/include/arpa/nameser.h
> +++ b/include/arpa/nameser.h
> @@ -55,6 +55,12 @@ int __ns_name_ntop (const unsigned char *, char *, size_t) __THROW;
> int __ns_name_unpack (const unsigned char *, const unsigned char *,
> const unsigned char *, unsigned char *, size_t) __THROW;
>
> +/* Like ns_samename, but for uncompressed binary names. Return true
> + if the two arguments compare are equal as case-insensitive domain
> + names. */
> +_Bool __ns_samebinaryname (const unsigned char *, const unsigned char *)
> + attribute_hidden;
> +
> #define ns_msg_getflag(handle, flag) \
> (((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift)
>
> diff --git a/resolv/Makefile b/resolv/Makefile
> index 0038bb7028..ec61ad07bd 100644
> --- a/resolv/Makefile
> +++ b/resolv/Makefile
> @@ -46,6 +46,7 @@ routines := \
> ns_name_skip \
> ns_name_uncompress \
> ns_name_unpack \
> + ns_samebinaryname \
> ns_samename \
> nsap_addr \
> nss_dns_functions \
> @@ -106,6 +107,10 @@ tests += \
> tests-internal += tst-resolv-txnid-collision
> tests-static += tst-resolv-txnid-collision
>
> +# Likewise for __ns_samebinaryname.
> +tests-internal += tst-ns_samebinaryname
> +tests-static += tst-ns_samebinaryname
> +
> # These tests need libdl.
> ifeq (yes,$(build-shared))
> tests += \
> diff --git a/resolv/ns_samebinaryname.c b/resolv/ns_samebinaryname.c
> new file mode 100644
> index 0000000000..9a47d8e97a
> --- /dev/null
> +++ b/resolv/ns_samebinaryname.c
> @@ -0,0 +1,55 @@
> +/* Compare two binary domain names for quality.
> + Copyright (C) 2022 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + 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 <arpa/nameser.h>
> +#include <stdbool.h>
> +
> +/* Convert ASCII letters to upper case. */
> +static inline int
> +ascii_toupper (unsigned char ch)
> +{
> + if (ch >= 'a' && ch <= 'z')
> + return ch - 'a' + 'A';
> + else
> + return ch;
> +}
> +
> +bool
> +__ns_samebinaryname (const unsigned char *a, const unsigned char *b)
> +{
> + while (*a != 0 && *b != 0)
> + {
> + if (*a != *b)
> + /* Different label length. */
> + return false;
> + int labellen = *a;
> + ++a;
> + ++b;
> + for (int i = 0; i < labellen; ++i)
> + {
> + if (*a != *b && ascii_toupper (*a) != ascii_toupper (*b))
> + /* Different character in label. */
> + return false;
> + ++a;
> + ++b;
> + }
> + }
> +
> + /* Match if both names are at the root label. */
> + return *a == 0 && *b == 0;
> +}
> diff --git a/resolv/tst-ns_samebinaryname.c b/resolv/tst-ns_samebinaryname.c
> new file mode 100644
> index 0000000000..b06ac610b4
> --- /dev/null
> +++ b/resolv/tst-ns_samebinaryname.c
> @@ -0,0 +1,62 @@
> +/* Test the __ns_samebinaryname function.
> + Copyright (C) 2022 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + 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 <arpa/nameser.h>
> +#include <array_length.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <support/check.h>
> +
> +/* First character denotes the comparison group: All names with the
> + same first character are expected to compare equal. */
> +static const char *const cases[] =
> + {
> + " ",
> + "1\001a", "1\001A",
> + "2\002ab", "2\002aB", "2\002Ab", "2\002AB",
> + "3\001a\002ab", "3\001A\002ab",
> + "w\003www\007example\003com", "w\003Www\007Example\003Com",
> + "w\003WWW\007EXAMPLE\003COM",
> + "W\003WWW", "W\003www",
> + };
> +
> +static int
> +do_test (void)
> +{
> + for (int i = 0; i < array_length (cases); ++i)
> + for (int j = 0; j < array_length (cases); ++j)
> + {
> + unsigned char *a = (unsigned char *) &cases[i][1];
> + unsigned char *b = (unsigned char *) &cases[j][1];
> + bool actual = __ns_samebinaryname (a, b);
> + bool expected = cases[i][0] == cases[j][0];
> + if (actual != expected)
> + {
> + char a1[NS_MAXDNAME];
> + TEST_VERIFY (ns_name_ntop (a, a1, sizeof (a1)) > 0);
> + char b1[NS_MAXDNAME];
> + TEST_VERIFY (ns_name_ntop (b, b1, sizeof (b1)) > 0);
> + printf ("error: \"%s\" \"%s\": expected %s\n",
> + a1, b1, expected ? "equal" : "unqueal");
> + support_record_failure ();
> + }
> + }
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
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