string: replace AsciiCaseInsensitiveKeyEqual with CaseInsensitiveEqual

This reverts commit eea38787b9 from PR #34242

We do not need comparators for HTTPHeaders since it is not using unordered_map anymore.
We only need a simple, locale-independent, ascii-only compare function for
a vector of key-value pairs of strings.

We have CaseInsensitiveEqual already in test utils, this commit moves
it to the strencodings module for use in the application code.

src/test/bech32_tests.cpp

@@ -4,7 +4,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <bech32.h>
-#include <test/util/str.h>
+#include <util/strencodings.h>
 
 #include <boost/test/unit_test.hpp>
 

src/test/fuzz/bech32.cpp

@@ -5,7 +5,6 @@
 #include <bech32.h>
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/FuzzedDataProvider.h>
-#include <test/util/str.h>
 #include <util/strencodings.h>
 
 #include <cassert>

src/test/util/CMakeLists.txt

@@ -13,7 +13,6 @@ add_library(test_util STATIC EXCLUDE_FROM_ALL
   random.cpp
   script.cpp
   setup_common.cpp
-  str.cpp
   time.cpp
   transaction_utils.cpp
   txmempool.cpp

src/test/util/str.cpp

@@ -1,21 +0,0 @@
-// Copyright (c) 2019-present The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#include <test/util/str.h>
-
-#include <cstdint>
-#include <string>
-
-bool CaseInsensitiveEqual(const std::string& s1, const std::string& s2)
-{
-    if (s1.size() != s2.size()) return false;
-    for (size_t i = 0; i < s1.size(); ++i) {
-        char c1 = s1[i];
-        if (c1 >= 'A' && c1 <= 'Z') c1 -= ('A' - 'a');
-        char c2 = s2[i];
-        if (c2 >= 'A' && c2 <= 'Z') c2 -= ('A' - 'a');
-        if (c1 != c2) return false;
-    }
-    return true;
-}

src/test/util/str.h

@@ -7,8 +7,6 @@
 
 #include <string>
 
-bool CaseInsensitiveEqual(const std::string& s1, const std::string& s2);
-
 /**
  * Increment a string. Useful to enumerate all fixed length strings with
  * characters in [min_char, max_char].

src/test/util_string_tests.cpp

@@ -4,7 +4,6 @@
 
 #include <util/strencodings.h>
 #include <util/string.h>
-#include <vector>
 
 #include <boost/test/unit_test.hpp>
 #include <test/util/common.h>
@@ -155,38 +154,27 @@ BOOST_AUTO_TEST_CASE(ConstevalFormatString_NumSpec)
         HasReason{"tinyformat: Too many conversion specifiers in format string"});
 }
 
-BOOST_AUTO_TEST_CASE(ascii_case_insensitive_key_equal_test)
+BOOST_AUTO_TEST_CASE(case_insensitive_equal_test)
 {
-    AsciiCaseInsensitiveKeyEqual cmp;
-    BOOST_CHECK(!cmp("A", "B"));
-    BOOST_CHECK(!cmp("A", "b"));
-    BOOST_CHECK(!cmp("a", "B"));
-    BOOST_CHECK(!cmp("B", "A"));
-    BOOST_CHECK(!cmp("B", "a"));
-    BOOST_CHECK(!cmp("b", "A"));
-    BOOST_CHECK(!cmp("A", "AA"));
-    BOOST_CHECK(cmp("A-A", "a-a"));
-    BOOST_CHECK(cmp("A", "A"));
-    BOOST_CHECK(cmp("A", "a"));
-    BOOST_CHECK(cmp("a", "a"));
-    BOOST_CHECK(cmp("B", "b"));
-    BOOST_CHECK(cmp("ab", "aB"));
-    BOOST_CHECK(cmp("Ab", "aB"));
-    BOOST_CHECK(cmp("AB", "ab"));
+    BOOST_CHECK(!CaseInsensitiveEqual("A", "B"));
+    BOOST_CHECK(!CaseInsensitiveEqual("A", "b"));
+    BOOST_CHECK(!CaseInsensitiveEqual("a", "B"));
+    BOOST_CHECK(!CaseInsensitiveEqual("B", "A"));
+    BOOST_CHECK(!CaseInsensitiveEqual("B", "a"));
+    BOOST_CHECK(!CaseInsensitiveEqual("b", "A"));
+    BOOST_CHECK(!CaseInsensitiveEqual("A", "AA"));
+    BOOST_CHECK(CaseInsensitiveEqual("A-A", "a-a"));
+    BOOST_CHECK(CaseInsensitiveEqual("A", "A"));
+    BOOST_CHECK(CaseInsensitiveEqual("A", "a"));
+    BOOST_CHECK(CaseInsensitiveEqual("a", "a"));
+    BOOST_CHECK(CaseInsensitiveEqual("B", "b"));
+    BOOST_CHECK(CaseInsensitiveEqual("ab", "aB"));
+    BOOST_CHECK(CaseInsensitiveEqual("Ab", "aB"));
+    BOOST_CHECK(CaseInsensitiveEqual("AB", "ab"));
 
     // Use a character with value > 127
     // to ensure we don't trigger implicit-integer-sign-change
-    BOOST_CHECK(!cmp("a", "\xe4"));
-}
-
-BOOST_AUTO_TEST_CASE(ascii_case_insensitive_hash_test)
-{
-    AsciiCaseInsensitiveHash hsh;
-    BOOST_CHECK_NE(hsh("A"), hsh("B"));
-    BOOST_CHECK_NE(hsh("AA"), hsh("A"));
-    BOOST_CHECK_EQUAL(hsh("A"), hsh("a"));
-    BOOST_CHECK_EQUAL(hsh("Ab"), hsh("aB"));
-    BOOST_CHECK_EQUAL(hsh("A\xfe"), hsh("a\xfe"));
+    BOOST_CHECK(!CaseInsensitiveEqual("a", "\xe4"));
 }
 
 BOOST_AUTO_TEST_CASE(line_reader_test)

src/util/strencodings.cpp

@@ -427,3 +427,16 @@ std::optional<uint64_t> ParseByteUnits(std::string_view str, ByteUnit default_mu
     }
     return *parsed_num * unit_amount;
 }
+
+bool CaseInsensitiveEqual(std::string_view s1, std::string_view s2)
+{
+    if (s1.size() != s2.size()) return false;
+    for (size_t i = 0; i < s1.size(); ++i) {
+        char c1 = s1[i];
+        if (c1 >= 'A' && c1 <= 'Z') c1 -= ('A' - 'a');
+        char c2 = s2[i];
+        if (c2 >= 'A' && c2 <= 'Z') c2 -= ('A' - 'a');
+        if (c1 != c2) return false;
+    }
+    return true;
+}

src/util/strencodings.h

@@ -325,6 +325,14 @@ std::string Capitalize(std::string str);
  */
 std::optional<uint64_t> ParseByteUnits(std::string_view str, ByteUnit default_multiplier);
 
+/**
+ *  Locale-independent, ASCII-only comparator
+ *  @param[in] s1 a string to compare
+ *  @param[in] s2 another string to compare
+ *  @returns true if s1 == s2 when both strings are converted to lowercase
+ */
+bool CaseInsensitiveEqual(std::string_view s1, std::string_view s2);
+
 namespace util {
 /** consteval version of HexDigit() without the lookup table. */
 consteval uint8_t ConstevalHexDigit(const char c)
@@ -353,20 +361,6 @@ struct Hex {
 };
 } // namespace detail
 
-struct AsciiCaseInsensitiveKeyEqual {
-    bool operator()(std::string_view s1, std::string_view s2) const
-    {
-        return ToLower(s1) == ToLower(s2);
-    }
-};
-
-struct AsciiCaseInsensitiveHash {
-    size_t operator()(std::string_view s) const
-    {
-        return std::hash<std::string>{}(ToLower(s));
-    }
-};
-
 /**
  * ""_hex is a compile-time user-defined literal returning a
  * `std::array<std::byte>`, equivalent to ParseHex(). Variants provided: