AK: Add IPv6Address class

This is the IPv6 counter part to the IPv4Address class and implements
parsing strings into a in6_addr and formatting one as a string. It
supports the address compression scheme as well as IPv4 mapped
addresses.

AK/IPv6Address.h

@@ -0,0 +1,302 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Endian.h>
+#include <AK/Format.h>
+#include <AK/Optional.h>
+#include <AK/StringView.h>
+#include <AK/Vector.h>
+
+#ifdef KERNEL
+#    include <AK/Error.h>
+#    include <Kernel/KString.h>
+#else
+#    include <AK/String.h>
+#endif
+#include <AK/IPv4Address.h>
+#include <AK/StringBuilder.h>
+
+namespace AK {
+
+class [[gnu::packed]] IPv6Address {
+public:
+    using in6_addr_t = u8[16];
+
+    constexpr IPv6Address() = default;
+
+    constexpr IPv6Address(in6_addr_t const& data)
+    {
+        for (size_t i = 0; i < 16; i++)
+            m_data[i] = data[i];
+    }
+
+    constexpr IPv6Address(IPv4Address const& ipv4_address)
+    {
+        // IPv4 mapped IPv6 address
+        m_data[10] = 0xff;
+        m_data[11] = 0xff;
+        m_data[12] = ipv4_address[0];
+        m_data[13] = ipv4_address[1];
+        m_data[14] = ipv4_address[2];
+        m_data[15] = ipv4_address[3];
+    }
+
+    constexpr u16 operator[](int i) const { return group(i); }
+
+#ifdef KERNEL
+    ErrorOr<NonnullOwnPtr<Kernel::KString>> to_string() const
+#else
+    String to_string() const
+#endif
+    {
+        if (is_zero()) {
+#ifdef KERNEL
+            return KString::try_create("::"sv);
+#else
+            return "::"sv;
+#endif
+        }
+
+        // TODO: Error propagation
+        StringBuilder builder;
+
+        if (is_ipv4_mapped()) {
+#ifdef KERNEL
+            return KString::formatted("::ffff:{}.{}.{}.{}", m_data[12], m_data[13], m_data[14], m_data[15]);
+#else
+            return String::formatted("::ffff:{}.{}.{}.{}", m_data[12], m_data[13], m_data[14], m_data[15]);
+#endif
+        }
+
+        // Find the start of the longest span of 0 values
+        Optional<int> longest_zero_span_start;
+        int zero_span_length = 0;
+        for (int i = 0; i < 8;) {
+            if (group(i) != 0) {
+                i++;
+                continue;
+            }
+            int contiguous_zeros = 1;
+            for (int j = i + 1; j < 8; j++) {
+                if (group(j) != 0)
+                    break;
+                contiguous_zeros++;
+            }
+
+            if (!longest_zero_span_start.has_value() || longest_zero_span_start.value() < contiguous_zeros) {
+                longest_zero_span_start = i;
+                zero_span_length = contiguous_zeros;
+            }
+
+            i += contiguous_zeros;
+        }
+
+        for (int i = 0; i < 8;) {
+            if (longest_zero_span_start.has_value() && longest_zero_span_start.value() == i) {
+                if (longest_zero_span_start.value() + zero_span_length >= 8)
+                    builder.append("::"sv);
+                else
+                    builder.append(':');
+                i += zero_span_length;
+                continue;
+            }
+
+            if (i == 0)
+                builder.appendff("{:x}", group(i));
+            else
+                builder.appendff(":{:x}", group(i));
+
+            i++;
+        }
+#ifdef KERNEL
+        return KString::try_create(builder.string_view());
+#else
+        return builder.string_view();
+#endif
+    }
+
+    static Optional<IPv6Address> from_string(StringView string)
+    {
+        if (string.is_null())
+            return {};
+
+        auto const parts = string.split_view(':', true);
+        if (parts.is_empty())
+            return {};
+        if (parts.size() > 9) {
+            // We may have 9 parts if the address is compressed
+            // at the beginning or end, e.g. by substituting the
+            // leading or trailing 0 with a : character. Otherwise,
+            // the maximum number of parts is 8, which we validate
+            // when expanding the compression.
+            return {};
+        }
+        if (parts.size() >= 4 && parts[parts.size() - 1].contains('.')) {
+            // Check if this may be an ipv4 mapped address
+            auto is_ipv4_prefix = [&]() {
+                auto separator_part = parts[parts.size() - 2].trim_whitespace();
+                if (separator_part.is_empty())
+                    return false;
+                auto separator_value = StringUtils::convert_to_uint_from_hex(separator_part);
+                if (!separator_value.has_value() || separator_value.value() != 0xffff)
+                    return false;
+                // TODO: this allows multiple compression tags "::" in the prefix, which is technically not legal
+                for (size_t i = 0; i < parts.size() - 2; i++) {
+                    auto part = parts[i].trim_whitespace();
+                    if (part.is_empty())
+                        continue;
+                    auto value = StringUtils::convert_to_uint_from_hex(part);
+                    if (!value.has_value() || value.value() != 0)
+                        return false;
+                }
+                return true;
+            };
+
+            if (is_ipv4_prefix()) {
+                auto ipv4_address = IPv4Address::from_string(parts[parts.size() - 1]);
+                if (ipv4_address.has_value())
+                    return IPv6Address(ipv4_address.value());
+                return {};
+            }
+        }
+
+        in6_addr_t addr {};
+        int group = 0;
+        int have_groups = 0;
+        bool found_compressed = false;
+        for (size_t i = 0; i < parts.size();) {
+            auto trimmed_part = parts[i].trim_whitespace();
+            if (trimmed_part.is_empty()) {
+                if (found_compressed)
+                    return {};
+                int empty_parts = 1;
+                bool is_leading = (i == 0);
+                bool is_trailing = false;
+                for (size_t j = i + 1; j < parts.size(); j++) {
+                    if (!parts[j].trim_whitespace().is_empty())
+                        break;
+                    empty_parts++;
+                    if (j == parts.size() - 1)
+                        is_trailing = true;
+                }
+                if (is_leading && is_trailing) {
+                    if (empty_parts > 3)
+                        return {};
+                    return IPv6Address();
+                }
+                if (is_leading || is_trailing) {
+                    if (empty_parts > 2)
+                        return {};
+                } else if (empty_parts > 1) {
+                    return {};
+                }
+
+                int remaining_parts = parts.size() - empty_parts - have_groups;
+                found_compressed = true;
+                group = 8 - remaining_parts;
+                VERIFY(group >= 0);
+                i += empty_parts;
+                continue;
+            } else {
+                i++;
+            }
+            auto part = StringUtils::convert_to_uint_from_hex(trimmed_part);
+            if (!part.has_value() || part.value() > 0xffff)
+                return {};
+
+            if (++have_groups > 8)
+                return {};
+
+            VERIFY(group < 8);
+            addr[group * sizeof(u16)] = (u8)(part.value() >> 8);
+            addr[group * sizeof(u16) + 1] = (u8)part.value();
+            group++;
+        }
+
+        return IPv6Address(addr);
+    }
+
+    constexpr in6_addr_t const& to_in6_addr_t() const { return m_data; }
+
+    constexpr bool operator==(IPv6Address const& other) const = default;
+    constexpr bool operator!=(IPv6Address const& other) const = default;
+
+    constexpr bool is_zero() const
+    {
+        for (auto& d : m_data) {
+            if (d != 0)
+                return false;
+        }
+        return true;
+    }
+
+    constexpr bool is_ipv4_mapped() const
+    {
+        if (m_data[0] || m_data[1] || m_data[2] || m_data[3] || m_data[4] || m_data[5] || m_data[6] || m_data[7] || m_data[8] || m_data[9])
+            return false;
+        if (m_data[10] != 0xff || m_data[11] != 0xff)
+            return false;
+        return true;
+    }
+
+    Optional<IPv4Address> ipv4_mapped_address() const
+    {
+        if (is_ipv4_mapped())
+            return IPv4Address(m_data[12], m_data[13], m_data[14], m_data[15]);
+        return {};
+    }
+
+private:
+    constexpr u16 group(unsigned i) const
+    {
+        VERIFY(i < 8);
+        return ((u16)m_data[i * sizeof(u16)] << 8) | m_data[i * sizeof(u16) + 1];
+    }
+
+    in6_addr_t m_data {};
+};
+
+static_assert(sizeof(IPv6Address) == 16);
+
+template<>
+struct Traits<IPv6Address> : public GenericTraits<IPv6Address> {
+    static constexpr unsigned hash(IPv6Address const& address)
+    {
+        unsigned h = 0;
+        for (int group = 0; group < 8; group += 2) {
+            u32 two_groups = ((u32)address[group] << 16) | (u32)address[group + 1];
+            if (group == 0)
+                h = int_hash(two_groups);
+            else
+                h = pair_int_hash(h, two_groups);
+        }
+        return h;
+    }
+};
+
+#ifdef KERNEL
+template<>
+struct Formatter<IPv6Address> : Formatter<ErrorOr<NonnullOwnPtr<Kernel::KString>>> {
+    ErrorOr<void> format(FormatBuilder& builder, IPv6Address const& value)
+    {
+        return Formatter<ErrorOr<NonnullOwnPtr<Kernel::KString>>>::format(builder, value.to_string());
+    }
+};
+#else
+template<>
+struct Formatter<IPv6Address> : Formatter<String> {
+    ErrorOr<void> format(FormatBuilder& builder, IPv6Address const& value)
+    {
+        return Formatter<String>::format(builder, value.to_string());
+    }
+};
+#endif
+
+}
+
+using AK::IPv6Address;

Tests/AK/CMakeLists.txt

@@ -32,6 +32,7 @@ set(AK_TEST_SOURCES
     TestHashTable.cpp
     TestHex.cpp
     TestIPv4Address.cpp
+    TestIPv6Address.cpp
     TestIndexSequence.cpp
     TestIntegerMath.cpp
     TestIntrusiveList.cpp

Tests/AK/TestIPv6Address.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <AK/Endian.h>
+#include <AK/IPv6Address.h>
+
+TEST_CASE(should_default_contructor_with_0s)
+{
+    constexpr IPv6Address addr {};
+
+    static_assert(addr.is_zero());
+
+    EXPECT(addr.is_zero());
+}
+
+TEST_CASE(should_construct_from_c_array)
+{
+    constexpr auto addr = [] {
+        u8 const a[16] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
+        return IPv6Address(a);
+    }();
+
+    static_assert(!addr.is_zero());
+
+    EXPECT(!addr.is_zero());
+}
+
+TEST_CASE(should_get_groups_by_index)
+{
+    constexpr IPv6Address addr({ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 });
+
+    static_assert(0x102 == addr[0]);
+    static_assert(0x304 == addr[1]);
+    static_assert(0x506 == addr[2]);
+    static_assert(0x708 == addr[3]);
+    static_assert(0x90a == addr[4]);
+    static_assert(0xb0c == addr[5]);
+    static_assert(0xd0e == addr[6]);
+    static_assert(0xf10 == addr[7]);
+
+    EXPECT_EQ(0x102, addr[0]);
+    EXPECT_EQ(0x304, addr[1]);
+    EXPECT_EQ(0x506, addr[2]);
+    EXPECT_EQ(0x708, addr[3]);
+    EXPECT_EQ(0x90a, addr[4]);
+    EXPECT_EQ(0xb0c, addr[5]);
+    EXPECT_EQ(0xd0e, addr[6]);
+    EXPECT_EQ(0xf10, addr[7]);
+}
+
+TEST_CASE(should_convert_to_string)
+{
+    EXPECT_EQ("102:304:506:708:90a:b0c:d0e:f10"sv, IPv6Address({ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }).to_string());
+    EXPECT_EQ("::"sv, IPv6Address().to_string());
+    EXPECT_EQ("::1"sv, IPv6Address({ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }).to_string());
+    EXPECT_EQ("1::"sv, IPv6Address({ 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }).to_string());
+    EXPECT_EQ("102:0:506:708:900::10"sv, IPv6Address({ 1, 2, 0, 0, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 16 }).to_string());
+    EXPECT_EQ("102:0:506:708:900::"sv, IPv6Address({ 1, 2, 0, 0, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0 }).to_string());
+    EXPECT_EQ("::304:506:708:90a:b0c:d0e:f10"sv, IPv6Address({ 0, 0, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }).to_string());
+    EXPECT_EQ("102:304::708:90a:b0c:d0e:f10"sv, IPv6Address({ 1, 2, 3, 4, 0, 0, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }).to_string());
+}
+
+TEST_CASE(should_make_ipv6_address_from_string)
+{
+    EXPECT(!IPv6Address::from_string(":::"sv).has_value());
+    EXPECT(!IPv6Address::from_string(":::1"sv).has_value());
+    EXPECT(!IPv6Address::from_string("1:::"sv).has_value());
+    EXPECT_EQ(IPv6Address::from_string("102:304:506:708:90a:b0c:d0e:f10"sv).value(), IPv6Address({ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }));
+    EXPECT_EQ(IPv6Address::from_string("::"sv).value(), IPv6Address());
+    EXPECT_EQ(IPv6Address::from_string("::1"sv).value(), IPv6Address({ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }));
+    EXPECT_EQ(IPv6Address::from_string("1::"sv).value(), IPv6Address({ 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }));
+    EXPECT_EQ(IPv6Address::from_string("102:0:506:708:900::10"sv).value(), IPv6Address({ 1, 2, 0, 0, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 16 }));
+    EXPECT_EQ(IPv6Address::from_string("102:0:506:708:900::"sv).value(), IPv6Address({ 1, 2, 0, 0, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0 }));
+    EXPECT_EQ(IPv6Address::from_string("::304:506:708:90a:b0c:d0e:f10"sv).value(), IPv6Address({ 0, 0, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }));
+    EXPECT_EQ(IPv6Address::from_string("102:304::708:90a:b0c:d0e:f10"sv).value(), IPv6Address({ 1, 2, 3, 4, 0, 0, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }));
+}
+
+TEST_CASE(ipv4_mapped_ipv6)
+{
+    auto ipv4_address_to_map = IPv4Address::from_string("192.168.0.1"sv).release_value();
+    IPv6Address mapped_address(ipv4_address_to_map);
+    EXPECT(mapped_address.is_ipv4_mapped());
+    EXPECT_EQ(ipv4_address_to_map, mapped_address.ipv4_mapped_address().value());
+    EXPECT_EQ("::ffff:192.168.0.1"sv, mapped_address.to_string());
+    EXPECT_EQ(IPv4Address(192, 168, 1, 9), IPv6Address::from_string("::FFFF:192.168.1.9"sv).value().ipv4_mapped_address().value());
+    EXPECT(!IPv6Address::from_string("::abcd:192.168.1.9"sv).has_value());
+}
+
+TEST_CASE(should_make_empty_optional_from_bad_string)
+{
+    auto const addr = IPv6Address::from_string("bad string"sv);
+
+    EXPECT(!addr.has_value());
+}
+
+TEST_CASE(should_make_empty_optional_from_out_of_range_values)
+{
+    auto const addr = IPv6Address::from_string("::10000"sv);
+
+    EXPECT(!addr.has_value());
+}
+
+TEST_CASE(should_compare)
+{
+    constexpr IPv6Address addr_a({ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 });
+    constexpr IPv6Address addr_b({ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17 });
+
+    static_assert(addr_a != addr_b);
+    static_assert(addr_a == addr_a);
+
+    EXPECT(addr_a != addr_b);
+    EXPECT(addr_a == addr_a);
+}