From 394085a34d25a51513019a4dc411acd3527fbd33 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 30 Aug 2022 10:02:49 +0200 Subject: 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 --- resolv/ns_samebinaryname.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 resolv/ns_samebinaryname.c (limited to 'resolv/ns_samebinaryname.c') 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 + . */ + +#include +#include + +/* 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; +} -- cgit v1.1