Split IP stuff into separate source and WIP implementation of name resolution.

source/mijin/net/ip.hpp

@@ -0,0 +1,53 @@
+#pragma once
+
+#if !defined(MIJIN_NET_IP_HPP_INCLUDED)
+#define MIJIN_NET_IP_HPP_INCLUDED 1
+
+#include <array>
+#include <variant>
+#include "../async/coroutine.hpp"
+#include "../container/optional.hpp"
+#include "../io/stream.hpp" // TODO: rename Stream{Error,Result} to IO{*}
+
+namespace mijin
+{
+struct IPv4Address
+{
+    std::array<std::uint8_t, 4> octets;
+
+    auto operator<=>(const IPv4Address&) const noexcept = default;
+
+    [[nodiscard]]
+    static Optional<IPv4Address> fromString(std::string_view stringView) noexcept;
+};
+
+struct IPv6Address
+{
+    std::array<std::uint16_t, 8> hextets;
+
+    auto operator<=>(const IPv6Address&) const noexcept = default;
+
+    [[nodiscard]]
+    static Optional<IPv6Address> fromString(std::string_view stringView) noexcept;
+};
+using ip_address_t = std::variant<IPv4Address, IPv6Address>;
+
+[[nodiscard]]
+inline Optional<ip_address_t> ipAddressFromString(std::string_view stringView) noexcept
+{
+    if (Optional<IPv4Address> ipv4Address = IPv4Address::fromString(stringView); !ipv4Address.empty())
+    {
+        return ip_address_t(*ipv4Address);
+    }
+    if (Optional<IPv6Address> ipv6Address = IPv6Address::fromString(stringView); !ipv6Address.empty())
+    {
+        return ip_address_t(*ipv6Address);
+    }
+    return NULL_OPTIONAL;
+}
+
+[[nodiscard]]
+Task<StreamResult<std::vector<ip_address_t>>> c_resolveHostname(std::string hostname) noexcept;
+}
+
+#endif // !defined(MIJIN_NET_IP_HPP_INCLUDED)