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author | Florian Weimer <fweimer@redhat.com> | 2022-08-30 10:02:49 +0200 |
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committer | Florian Weimer <fweimer@redhat.com> | 2022-08-30 10:02:49 +0200 |
commit | 394085a34d25a51513019a4dc411acd3527fbd33 (patch) | |
tree | fafedbaebad9ec3d6049ca00f57cfa6dbc094983 /resolv/ns_samebinaryname.c | |
parent | c79327bf00a4be6d60259227acc78ef80ead3622 (diff) | |
download | glibc-394085a34d25a51513019a4dc411acd3527fbd33.zip glibc-394085a34d25a51513019a4dc411acd3527fbd33.tar.gz glibc-394085a34d25a51513019a4dc411acd3527fbd33.tar.bz2 |
resolv: Add the __ns_samebinaryname function
During packet parsing, only the binary name is available. If the name
equality check is performed before conversion to text, we can sometimes
skip the last step.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Diffstat (limited to 'resolv/ns_samebinaryname.c')
-rw-r--r-- | resolv/ns_samebinaryname.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/resolv/ns_samebinaryname.c b/resolv/ns_samebinaryname.c new file mode 100644 index 0000000..9a47d8e --- /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; +} |