mpd/src/net/StaticSocketAddress.hxx

/*
 * Copyright 2012-2021 Max Kellermann <max.kellermann@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef STATIC_SOCKET_ADDRESS_HXX
#define STATIC_SOCKET_ADDRESS_HXX

#include "SocketAddress.hxx" // IWYU pragma: export
#include "Features.hxx"

#include <cassert>
#include <string_view>

/**
 * An OO wrapper for struct sockaddr_storage.
 */
class StaticSocketAddress {
	friend class SocketDescriptor;

public:
	typedef SocketAddress::size_type size_type;

private:
	size_type size;
	struct sockaddr_storage address;

public:
	StaticSocketAddress() = default;

	StaticSocketAddress &operator=(SocketAddress other) noexcept;

	constexpr operator SocketAddress() const noexcept {
		return SocketAddress(*this, size);
	}

	constexpr operator struct sockaddr *() noexcept {
		return (struct sockaddr *)(void *)&address;
	}

	constexpr operator const struct sockaddr *() const noexcept {
		return (const struct sockaddr *)(const void *)&address;
	}

	/**
	 * Cast the "sockaddr" pointer to a different address type,
	 * e.g. "sockaddr_in".  This is only legal after checking
	 * GetFamily().
	 */
	template<typename T>
	constexpr const T &CastTo() const noexcept {
		/* cast through void to work around the bogus
		   alignment warning */
		const void *q = reinterpret_cast<const void *>(&address);
		return *reinterpret_cast<const T *>(q);
	}

	constexpr size_type GetCapacity() const noexcept {
		return sizeof(address);
	}

	size_type GetSize() const noexcept {
		return size;
	}

	void SetSize(size_type _size) noexcept {
		assert(_size > 0);
		assert(size_t(_size) <= sizeof(address));

		size = _size;
	}

	/**
	 * Set the size to the maximum value for this class.
	 */
	void SetMaxSize() {
		SetSize(GetCapacity());
	}

	int GetFamily() const noexcept {
		return address.ss_family;
	}

	bool IsDefined() const noexcept {
		return GetFamily() != AF_UNSPEC;
	}

	void Clear() noexcept {
		size = sizeof(address.ss_family);
		address.ss_family = AF_UNSPEC;
	}

#ifdef HAVE_UN
	/**
	 * @see SocketAddress::GetLocalRaw()
	 */
	[[gnu::pure]]
	std::string_view GetLocalRaw() const noexcept;
#endif

#ifdef HAVE_TCP
	/**
	 * Extract the port number.  Returns 0 if not applicable.
	 */
	[[gnu::pure]]
	unsigned GetPort() const noexcept {
		return ((SocketAddress)*this).GetPort();
	}

	/**
	 * @return true on success, false if this address cannot have
	 * a port number
	 */
	bool SetPort(unsigned port) noexcept;
#endif

	[[gnu::pure]]
	bool operator==(SocketAddress other) const noexcept {
		return (SocketAddress)*this == other;
	}

	bool operator!=(SocketAddress other) const noexcept {
		return !(*this == other);
	}
};

#endif