Add header::difficulty, and config::version (4 segment uint32_t).

Makefile.am

@@ -82,6 +82,7 @@ src_libbitcoin_system_la_SOURCES = \
     src/config/transaction.cpp \
     src/config/url.cpp \
     src/config/utilities.cpp \
+    src/config/version.cpp \
     src/crypto/aes256.cpp \
     src/crypto/der_parser.cpp \
     src/crypto/ec_context.cpp \
@@ -261,6 +262,7 @@ test_libbitcoin_system_test_SOURCES = \
     test/config/printer.cpp \
     test/config/url.cpp \
     test/config/utilities.cpp \
+    test/config/version.cpp \
     test/crypto/aes256.cpp \
     test/crypto/elliptic_curve.cpp \
     test/crypto/pseudo_random.cpp \
@@ -533,7 +535,8 @@ include_bitcoin_system_config_HEADERS = \
     include/bitcoin/system/config/script.hpp \
     include/bitcoin/system/config/transaction.hpp \
     include/bitcoin/system/config/url.hpp \
-    include/bitcoin/system/config/utilities.hpp
+    include/bitcoin/system/config/utilities.hpp \
+    include/bitcoin/system/config/version.hpp
 
 include_bitcoin_system_cryptodir = ${includedir}/bitcoin/system/crypto
 include_bitcoin_system_crypto_HEADERS = \

builds/cmake/CMakeLists.txt

@@ -515,6 +515,7 @@ add_library( ${CANONICAL_LIB_NAME}
     "../../src/config/transaction.cpp"
     "../../src/config/url.cpp"
     "../../src/config/utilities.cpp"
+    "../../src/config/version.cpp"
     "../../src/crypto/aes256.cpp"
     "../../src/crypto/der_parser.cpp"
     "../../src/crypto/ec_context.cpp"
@@ -740,6 +741,7 @@ if (with-tests)
         "../../test/config/printer.cpp"
         "../../test/config/url.cpp"
         "../../test/config/utilities.cpp"
+        "../../test/config/version.cpp"
         "../../test/crypto/aes256.cpp"
         "../../test/crypto/elliptic_curve.cpp"
         "../../test/crypto/pseudo_random.cpp"

builds/msvc/vs2022/libbitcoin-system-test/libbitcoin-system-test.vcxproj

@@ -161,6 +161,7 @@
     <ClCompile Include="..\..\..\..\test\config\printer.cpp" />
     <ClCompile Include="..\..\..\..\test\config\url.cpp" />
     <ClCompile Include="..\..\..\..\test\config\utilities.cpp" />
+    <ClCompile Include="..\..\..\..\test\config\version.cpp" />
     <ClCompile Include="..\..\..\..\test\constants.cpp" />
     <ClCompile Include="..\..\..\..\test\constraints.cpp" />
     <ClCompile Include="..\..\..\..\test\crypto\aes256.cpp" />

builds/msvc/vs2022/libbitcoin-system-test/libbitcoin-system-test.vcxproj.filters

@@ -219,6 +219,9 @@
     <ClCompile Include="..\..\..\..\test\config\utilities.cpp">
       <Filter>src\config</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\..\test\config\version.cpp">
+      <Filter>src\config</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\..\test\constants.cpp">
       <Filter>src</Filter>
     </ClCompile>

builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.vcxproj

@@ -195,6 +195,7 @@
     </ClCompile>
     <ClCompile Include="..\..\..\..\src\config\url.cpp" />
     <ClCompile Include="..\..\..\..\src\config\utilities.cpp" />
+    <ClCompile Include="..\..\..\..\src\config\version.cpp" />
     <ClCompile Include="..\..\..\..\src\crypto\aes256.cpp" />
     <ClCompile Include="..\..\..\..\src\crypto\der_parser.cpp" />
     <ClCompile Include="..\..\..\..\src\crypto\ec_context.cpp" />
@@ -357,6 +358,7 @@
     <ClInclude Include="..\..\..\..\include\bitcoin\system\config\transaction.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\system\config\url.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\system\config\utilities.hpp" />
+    <ClInclude Include="..\..\..\..\include\bitcoin\system\config\version.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\system\constants.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\system\constraints.hpp" />
     <ClInclude Include="..\..\..\..\include\bitcoin\system\crypto\aes256.hpp" />

builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.vcxproj.filters

@@ -381,6 +381,9 @@
     <ClCompile Include="..\..\..\..\src\config\utilities.cpp">
       <Filter>src\config</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\..\src\config\version.cpp">
+      <Filter>src\config</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\..\src\crypto\aes256.cpp">
       <Filter>src\crypto</Filter>
     </ClCompile>
@@ -821,6 +824,9 @@
     <ClInclude Include="..\..\..\..\include\bitcoin\system\config\utilities.hpp">
       <Filter>include\bitcoin\system\config</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\..\..\include\bitcoin\system\config\version.hpp">
+      <Filter>include\bitcoin\system\config</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\..\..\include\bitcoin\system\constants.hpp">
       <Filter>include\bitcoin\system</Filter>
     </ClInclude>

include/bitcoin/system/chain/header.hpp

@@ -81,7 +81,6 @@ class BC_API header
     void to_data(std::ostream& stream) const NOEXCEPT;
     void to_data(writer& sink) const NOEXCEPT;
 
-
     /// Properties.
     /// -----------------------------------------------------------------------
     /// Native properties.
@@ -96,6 +95,7 @@ class BC_API header
     /// Computed properties.
     uint256_t proof() const NOEXCEPT;
     hash_digest hash() const NOEXCEPT;
+    double difficulty() const NOEXCEPT;
 
     /// Cache and metadata.
     /// -----------------------------------------------------------------------

include/bitcoin/system/config/config.hpp

@@ -41,5 +41,6 @@
 #include <bitcoin/system/config/transaction.hpp>
 #include <bitcoin/system/config/url.hpp>
 #include <bitcoin/system/config/utilities.hpp>
+#include <bitcoin/system/config/version.hpp>
 
 #endif

include/bitcoin/system/config/version.hpp

@@ -0,0 +1,104 @@
+/**
+ * Copyright (c) 2011-2025 libbitcoin developers (see AUTHORS)
+ *
+ * This file is part of libbitcoin.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef LIBBITCOIN_SYSTEM_CONFIG_VERSION_HPP
+#define LIBBITCOIN_SYSTEM_CONFIG_VERSION_HPP
+
+#include <memory>
+#include <bitcoin/system/define.hpp>
+
+namespace libbitcoin {
+namespace system {
+namespace config {
+
+/// Container for a protocol version tuple with up to four segments.
+/// Segments are non-negative integers, padded with zeros for fewer than four.
+/// The format is major.minor[.subminor[.patch]] with at least one dot.
+class BC_API version
+{
+public:
+    typedef std::shared_ptr<version> ptr;
+
+    DEFAULT_COPY_MOVE_DESTRUCT(version);
+
+    version() NOEXCEPT;
+
+    /// Deserialize from dotted string (throws on invalid format).
+    version(const std::string& version_str) THROWS;
+
+    /// Construct from individual segments (2 to 4, pads with zeros).
+    version(uint32_t major, uint32_t minor, uint32_t subminor={},
+        uint32_t patch={}) NOEXCEPT;
+
+    /// Properties.
+    /// -----------------------------------------------------------------------
+
+    /// Access to the internal segments array.
+    const std::array<uint32_t, 4>& segments() const NOEXCEPT;
+
+    /// Methods.
+    /// -----------------------------------------------------------------------
+
+    /// The version is 0.0.0.0.
+    bool is_default() const NOEXCEPT;
+
+    /// Serialize to dot string, omitting trailing zero segments (minimum 2).
+    std::string to_string() const NOEXCEPT;
+
+    /// Operators.
+    /// -----------------------------------------------------------------------
+
+    /// Deserialize from input stream (throws on invalid format).
+    friend std::istream& operator>>(std::istream& input, version& argument) THROWS;
+
+    /// Serialize to output stream.
+    friend std::ostream& operator<<(std::ostream& output,
+        const version& argument) NOEXCEPT;
+
+private:
+    // This is not thread safe.
+    std::array<uint32_t, 4> segments_;
+};
+
+/// Lexicographical comparison.
+BC_API bool operator==(const version& left, const version& right) NOEXCEPT;
+BC_API bool operator!=(const version& left, const version& right) NOEXCEPT;
+BC_API bool operator<(const version& left, const version& right) NOEXCEPT;
+BC_API bool operator<=(const version& left, const version& right) NOEXCEPT;
+BC_API bool operator>(const version& left, const version& right) NOEXCEPT;
+BC_API bool operator>=(const version& left, const version& right) NOEXCEPT;
+
+typedef std::vector<version> versions;
+
+} // namespace config
+} // namespace system
+} // namespace libbitcoin
+
+namespace std
+{
+template<>
+struct hash<bc::system::config::version>
+{
+    size_t operator()(const bc::system::config::version& value) const NOEXCEPT
+    {
+        return std::hash<std::string>{}(value.to_string());
+    }
+};
+} // namespace std
+
+#endif

include/bitcoin/system/impl/serial/deserialize.ipp

@@ -22,6 +22,7 @@
 #include <algorithm>
 #include <iterator>
 #include <sstream>
+#include <utility>
 #include <bitcoin/system/data/data.hpp>
 #include <bitcoin/system/define.hpp>
 #include <bitcoin/system/math/math.hpp>
@@ -107,7 +108,14 @@ bool deserialize(Value& out, const std::string_view& text) NOEXCEPT
     // This can convert garbage to zero, use is_ascii_number for pre-assurance.
     try
     {
-        std::istringstream istream(trim_copy(text));
+        auto trimmed = trim_copy(text);
+        if constexpr (is_integer<Value> && !is_signed<Value>)
+        {
+            if (!trimmed.empty() && trimmed.front() == '-')
+                return false;
+        }
+
+        std::istringstream istream(std::move(trimmed));
         istream >> out;
         return !istream.fail();
     }

src/chain/header.cpp

@@ -268,6 +268,29 @@ hash_digest header::hash() const NOEXCEPT
     return digest;
 }
 
+// computed, not used in consensus.
+double header::difficulty() const NOEXCEPT
+{
+    auto shift = bit_and(shift_right(bits_, 24), 0xff_u32);
+    auto difference =
+        static_cast<double>(0x0000ffff_u32) /
+        static_cast<double>(bit_and(bits_, 0x00ffffff_u32));
+
+    while (shift < 29u)
+    {
+        difference *= 256.0;
+        ++shift;
+    }
+
+    while (shift > 29u)
+    {
+        difference /= 256.0;
+        --shift;
+    }
+
+    return difference;
+}
+
 // Cache and metadata.
 // ----------------------------------------------------------------------------