multicast_membership.hpp

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#pragma once
 
/// @file userver/engine/io/multicast_membership.hpp
/// @brief @copybrief engine::io::IpMreq
 
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
 
#include <stdexcept>
 
USERVER_NAMESPACE_BEGIN
 
namespace engine::io {
 
/// Multicast request related exceptions
class IpMulticastRequestException : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
};
 
class Socket;
 
/// Native ip multicast request wrapper
/// @snippet src/engine/io/socket_test.cpp multicast socket creation sample
class IpMreq final {
public:
    /// @brief Creates a structure storing multicast group membership request information. The resulting object may be
    /// passed to @ref engine::io::AddMembership() and @ref engine::io::DropMembership() functions.
    /// @note IP version is chosen automatically from ip_multiaddr value.
    /// @param ip_multiaddr IP multicast group address (e.g. 239.255.0.1" or "ff02::1")
    /// @param interface_index Interface index (0 for default);
    IpMreq(const char* ip_multiaddr, unsigned int interface_index);
 
    /// @brief Native multicast request structure pointer.
    void* Data() { return &data_; }
 
    /// @brief Native multicast request structure pointer.
    const void* Data() const { return &data_; }
 
    /// @brief Returns socket option level.
    int GetSocketOptionLevel() const noexcept { return (family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6); }
 
    /// @brief Returns socket option name for joining multicast group.
    int GetJoinSocketOptionName() const noexcept { return (family_ == AF_INET ? IP_ADD_MEMBERSHIP : IPV6_JOIN_GROUP); }
 
    /// @brief Returns socket option name for leaving multicast group.
    int GetLeaveSocketOption() const noexcept { return (family_ == AF_INET ? IP_DROP_MEMBERSHIP : IPV6_LEAVE_GROUP); }
 
    /// Returns appropriate size for setsockopt based on address family.
    size_t Size() const noexcept { return (family_ == AF_INET ? sizeof(struct ip_mreqn) : sizeof(struct ipv6_mreq)); }
 
private:
    union Storage {
        struct ip_mreqn ip_req;
        struct ipv6_mreq ipv6_req;
    } data_;
    int family_;
};
 
/// @brief Joins multicast group for given socket to receive multicast datagrams.
void AddMembership(Socket& socket, const IpMreq& mreq);
 
/// @brief Leaves multicast group for given socket previously joined with AddMembership.
void DropMembership(Socket& socket, const IpMreq& mreq);
 
}  // namespace engine::io
 
USERVER_NAMESPACE_END