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// Copyright (C) 2018 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef DHCP_SOCKET_INFO_H
#define DHCP_SOCKET_INFO_H
#include <asiolink/io_address.h>
#include <cstdint>
namespace isc {
namespace dhcp {
/// Holds information about socket.
struct SocketInfo {
isc::asiolink::IOAddress addr_; /// bound address
uint16_t port_; /// socket port
uint16_t family_; /// IPv4 or IPv6
/// @brief Socket descriptor (a.k.a. primary socket).
int sockfd_;
/// @brief Fallback socket descriptor.
///
/// This socket descriptor holds the handle to the fallback socket.
/// The fallback socket is created when there is a need for the regular
/// datagram socket to be bound to an IP address and port, besides
/// primary socket (sockfd_) which is actually used to receive and process
/// the DHCP messages. The fallback socket (if exists) is always associated
/// with the primary socket. In particular, the need for the fallback socket
/// arises when raw socket is a primary one. When primary socket is open,
/// it is bound to an interface not the address and port. The implications
/// include the possibility that the other process (e.g. the other instance
/// of DHCP server) will bind to the same address and port through which the
/// raw socket receives the DHCP messages. Another implication is that the
/// kernel, being unaware of the DHCP server operating through the raw
/// socket, will respond with the ICMP "Destination port unreachable"
/// messages when DHCP messages are only received through the raw socket.
/// In order to workaround the issues mentioned here, the fallback socket
/// should be opened so as/ the kernel is aware that the certain address
/// and port is in use.
///
/// The fallback description is supposed to be set to a negative value if
/// the fallback socket is closed (not open).
int fallbackfd_;
/// @brief SocketInfo constructor.
///
/// @param addr An address the socket is bound to.
/// @param port A port the socket is bound to.
/// @param sockfd Socket descriptor.
/// @param fallbackfd A descriptor of the fallback socket.
SocketInfo(const isc::asiolink::IOAddress& addr, const uint16_t port,
const int sockfd, const int fallbackfd = -1)
: addr_(addr), port_(port), family_(addr.getFamily()),
sockfd_(sockfd), fallbackfd_(fallbackfd) { }
};
}; // namespace isc::dhcp
}; // namespace isc
#endif // DHCP_SOCKET_INFO_H
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