libzmq/src/udp_engine.cpp

/*
Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file

This file is part of libzmq, the ZeroMQ core engine in C++.

libzmq is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

As a special exception, the Contributors give you permission to link
this library with independent modules to produce an executable,
regardless of the license terms of these independent modules, and to
copy and distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent module, the
terms and conditions of the license of that module. An independent
module is a module which is not derived from or based on this library.
If you modify this library, you must extend this exception to your
version of the library.

libzmq is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "precompiled.hpp"

#if !defined ZMQ_HAVE_WINDOWS
#include <sys/types.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#ifdef ZMQ_HAVE_VXWORKS
#include <sockLib.h>
#endif
#endif

#include "udp_address.hpp"
#include "udp_engine.hpp"
#include "session_base.hpp"
#include "err.hpp"
#include "ip.hpp"

//  OSX uses a different name for this socket option
#ifndef IPV6_ADD_MEMBERSHIP
#define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
#endif

#ifdef __APPLE__
#include <TargetConditionals.h>
#endif

zmq::udp_engine_t::udp_engine_t (const options_t &options_) :
    _plugged (false),
    _fd (-1),
    _session (NULL),
    _handle (static_cast<handle_t> (NULL)),
    _address (NULL),
    _options (options_),
    _send_enabled (false),
    _recv_enabled (false)
{
}

zmq::udp_engine_t::~udp_engine_t ()
{
    zmq_assert (!_plugged);

    if (_fd != retired_fd) {
#ifdef ZMQ_HAVE_WINDOWS
        const int rc = closesocket (_fd);
        wsa_assert (rc != SOCKET_ERROR);
#else
        int rc = close (_fd);
        errno_assert (rc == 0);
#endif
        _fd = retired_fd;
    }
}

int zmq::udp_engine_t::init (address_t *address_, bool send_, bool recv_)
{
    zmq_assert (address_);
    zmq_assert (send_ || recv_);
    _send_enabled = send_;
    _recv_enabled = recv_;
    _address = address_;

    _fd = open_socket (_address->resolved.udp_addr->family (), SOCK_DGRAM,
                       IPPROTO_UDP);
    if (_fd == retired_fd)
        return -1;

    unblock_socket (_fd);

    return 0;
}

void zmq::udp_engine_t::plug (io_thread_t *io_thread_, session_base_t *session_)
{
    zmq_assert (!_plugged);
    _plugged = true;

    zmq_assert (!_session);
    zmq_assert (session_);
    _session = session_;

    //  Connect to I/O threads poller object.
    io_object_t::plug (io_thread_);
    _handle = add_fd (_fd);

    const udp_address_t *const udp_addr = _address->resolved.udp_addr;

    int rc = 0;

    // Bind the socket to a device if applicable
    if (!_options.bound_device.empty ()) {
        rc = rc | bind_to_device (_fd, _options.bound_device);
        if (rc != 0) {
            assert_success_or_recoverable (_fd, rc);
            error (connection_error);
            return;
        }
    }

    if (_send_enabled) {
        if (!_options.raw_socket) {
            const ip_addr_t *out = udp_addr->target_addr ();
            _out_address = out->as_sockaddr ();
            _out_address_len = out->sockaddr_len ();

            if (out->is_multicast ()) {
                const bool is_ipv6 = (out->family () == AF_INET6);
                rc = rc
                     | set_udp_multicast_loop (_fd, is_ipv6,
                                               _options.multicast_loop);

                if (_options.multicast_hops > 0) {
                    rc = rc
                         | set_udp_multicast_ttl (_fd, is_ipv6,
                                                  _options.multicast_hops);
                }

                rc = rc | set_udp_multicast_iface (_fd, is_ipv6, udp_addr);
            }
        } else {
            /// XXX fixme ?
            _out_address = reinterpret_cast<sockaddr *> (&_raw_address);
            _out_address_len =
              static_cast<zmq_socklen_t> (sizeof (sockaddr_in));
        }
    }

    if (_recv_enabled) {
        rc = rc | set_udp_reuse_address (_fd, true);

        const ip_addr_t *bind_addr = udp_addr->bind_addr ();
        ip_addr_t any = ip_addr_t::any (bind_addr->family ());
        const ip_addr_t *real_bind_addr;

        const bool multicast = udp_addr->is_mcast ();

        if (multicast) {
            //  Multicast addresses should be allowed to bind to more than
            //  one port as all ports should receive the message
            rc = rc | set_udp_reuse_port (_fd, true);

            //  In multicast we should bind ANY and use the mreq struct to
            //  specify the interface
            any.set_port (bind_addr->port ());

            real_bind_addr = &any;
        } else {
            real_bind_addr = bind_addr;
        }

        if (rc != 0) {
            error (protocol_error);
            return;
        }

#ifdef ZMQ_HAVE_VXWORKS
        rc = rc
             | bind (_fd, (sockaddr *) real_bind_addr->as_sockaddr (),
                     real_bind_addr->sockaddr_len ());
#else
        rc = rc
             | bind (_fd, real_bind_addr->as_sockaddr (),
                     real_bind_addr->sockaddr_len ());
#endif
        if (rc != 0) {
            assert_success_or_recoverable (_fd, rc);
            error (connection_error);
            return;
        }

        if (multicast) {
            rc = rc | add_membership (_fd, udp_addr);
        }
    }

    if (rc != 0) {
        error (protocol_error);
    } else {
        if (_send_enabled) {
            set_pollout (_handle);
        }

        if (_recv_enabled) {
            set_pollin (_handle);

            //  Call restart output to drop all join/leave commands
            restart_output ();
        }
    }
}

int zmq::udp_engine_t::set_udp_multicast_loop (fd_t s_,
                                               bool is_ipv6_,
                                               bool loop_)
{
    int level;
    int optname;

    if (is_ipv6_) {
        level = IPPROTO_IPV6;
        optname = IPV6_MULTICAST_LOOP;
    } else {
        level = IPPROTO_IP;
        optname = IP_MULTICAST_LOOP;
    }

    int loop = loop_ ? 1 : 0;
    const int rc = setsockopt (s_, level, optname,
                               reinterpret_cast<char *> (&loop), sizeof (loop));
    assert_success_or_recoverable (s_, rc);
    return rc;
}

int zmq::udp_engine_t::set_udp_multicast_ttl (fd_t s_, bool is_ipv6_, int hops_)
{
    int level;

    if (is_ipv6_) {
        level = IPPROTO_IPV6;
    } else {
        level = IPPROTO_IP;
    }

    const int rc =
      setsockopt (s_, level, IP_MULTICAST_TTL,
                  reinterpret_cast<char *> (&hops_), sizeof (hops_));
    assert_success_or_recoverable (s_, rc);
    return rc;
}

int zmq::udp_engine_t::set_udp_multicast_iface (fd_t s_,
                                                bool is_ipv6_,
                                                const udp_address_t *addr_)
{
    int rc = 0;

    if (is_ipv6_) {
        int bind_if = addr_->bind_if ();

        if (bind_if > 0) {
            //  If a bind interface is provided we tell the
            //  kernel to use it to send multicast packets
            rc = setsockopt (s_, IPPROTO_IPV6, IPV6_MULTICAST_IF,
                             reinterpret_cast<char *> (&bind_if),
                             sizeof (bind_if));
        }
    } else {
        struct in_addr bind_addr = addr_->bind_addr ()->ipv4.sin_addr;

        if (bind_addr.s_addr != INADDR_ANY) {
            rc = setsockopt (s_, IPPROTO_IP, IP_MULTICAST_IF,
                             reinterpret_cast<char *> (&bind_addr),
                             sizeof (bind_addr));
        }
    }

    assert_success_or_recoverable (s_, rc);
    return rc;
}

int zmq::udp_engine_t::set_udp_reuse_address (fd_t s_, bool on_)
{
    int on = on_ ? 1 : 0;
    const int rc = setsockopt (s_, SOL_SOCKET, SO_REUSEADDR,
                               reinterpret_cast<char *> (&on), sizeof (on));
    assert_success_or_recoverable (s_, rc);
    return rc;
}

int zmq::udp_engine_t::set_udp_reuse_port (fd_t s_, bool on_)
{
#ifndef SO_REUSEPORT
    return 0;
#else
    int on = on_ ? 1 : 0;
    int rc = setsockopt (s_, SOL_SOCKET, SO_REUSEPORT,
                         reinterpret_cast<char *> (&on), sizeof (on));
    assert_success_or_recoverable (s_, rc);
    return rc;
#endif
}

int zmq::udp_engine_t::add_membership (fd_t s_, const udp_address_t *addr_)
{
    const ip_addr_t *mcast_addr = addr_->target_addr ();
    int rc = 0;

    if (mcast_addr->family () == AF_INET) {
        struct ip_mreq mreq;
        mreq.imr_multiaddr = mcast_addr->ipv4.sin_addr;
        mreq.imr_interface = addr_->bind_addr ()->ipv4.sin_addr;

        rc = setsockopt (s_, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                         reinterpret_cast<char *> (&mreq), sizeof (mreq));

    } else if (mcast_addr->family () == AF_INET6) {
        struct ipv6_mreq mreq;
        const int iface = addr_->bind_if ();

        zmq_assert (iface >= -1);

        mreq.ipv6mr_multiaddr = mcast_addr->ipv6.sin6_addr;
        mreq.ipv6mr_interface = iface;

        rc = setsockopt (s_, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
                         reinterpret_cast<char *> (&mreq), sizeof (mreq));
    }

    assert_success_or_recoverable (s_, rc);
    return rc;
}

void zmq::udp_engine_t::error (error_reason_t reason_)
{
    zmq_assert (_session);
    _session->engine_error (false, reason_);
    terminate ();
}

void zmq::udp_engine_t::terminate ()
{
    zmq_assert (_plugged);
    _plugged = false;

    rm_fd (_handle);

    //  Disconnect from I/O threads poller object.
    io_object_t::unplug ();

    delete this;
}

void zmq::udp_engine_t::sockaddr_to_msg (zmq::msg_t *msg_,
                                         const sockaddr_in *addr_)
{
    const char *const name = inet_ntoa (addr_->sin_addr);

    char port[6];
    const int port_len =
      sprintf (port, "%d", static_cast<int> (ntohs (addr_->sin_port)));
    zmq_assert (port_len > 0);

    const size_t name_len = strlen (name);
    const int size = static_cast<int> (name_len) + 1 /* colon */
                     + port_len + 1;                 //  terminating NUL
    const int rc = msg_->init_size (size);
    errno_assert (rc == 0);
    msg_->set_flags (msg_t::more);

    //  use memcpy instead of strcpy/strcat, since this is more efficient when
    //  we already know the lengths, which we calculated above
    char *address = static_cast<char *> (msg_->data ());
    memcpy (address, name, name_len);
    address += name_len;
    *address++ = ':';
    memcpy (address, port, static_cast<size_t> (port_len));
    address += port_len;
    *address = 0;
}

int zmq::udp_engine_t::resolve_raw_address (const char *name_, size_t length_)
{
    memset (&_raw_address, 0, sizeof _raw_address);

    const char *delimiter = NULL;

    // Find delimiter, cannot use memrchr as it is not supported on windows
    if (length_ != 0) {
        int chars_left = static_cast<int> (length_);
        const char *current_char = name_ + length_;
        do {
            if (*(--current_char) == ':') {
                delimiter = current_char;
                break;
            }
        } while (--chars_left != 0);
    }

    if (!delimiter) {
        errno = EINVAL;
        return -1;
    }

    const std::string addr_str (name_, delimiter - name_);
    const std::string port_str (delimiter + 1, name_ + length_ - delimiter - 1);

    //  Parse the port number (0 is not a valid port).
    const uint16_t port = static_cast<uint16_t> (atoi (port_str.c_str ()));
    if (port == 0) {
        errno = EINVAL;
        return -1;
    }

    _raw_address.sin_family = AF_INET;
    _raw_address.sin_port = htons (port);
    _raw_address.sin_addr.s_addr = inet_addr (addr_str.c_str ());

    if (_raw_address.sin_addr.s_addr == INADDR_NONE) {
        errno = EINVAL;
        return -1;
    }

    return 0;
}

void zmq::udp_engine_t::out_event ()
{
    msg_t group_msg;
    int rc = _session->pull_msg (&group_msg);
    errno_assert (rc == 0 || (rc == -1 && errno == EAGAIN));

    if (rc == 0) {
        msg_t body_msg;
        rc = _session->pull_msg (&body_msg);
        //  If there's a group, there should also be a body
        errno_assert (rc == 0);

        const size_t group_size = group_msg.size ();
        const size_t body_size = body_msg.size ();
        size_t size;

        if (_options.raw_socket) {
            rc = resolve_raw_address (static_cast<char *> (group_msg.data ()),
                                      group_size);

            //  We discard the message if address is not valid
            if (rc != 0) {
                rc = group_msg.close ();
                errno_assert (rc == 0);

                rc = body_msg.close ();
                errno_assert (rc == 0);

                return;
            }

            size = body_size;

            memcpy (_out_buffer, body_msg.data (), body_size);
        } else {
            size = group_size + body_size + 1;

            // TODO: check if larger than maximum size
            _out_buffer[0] = static_cast<unsigned char> (group_size);
            memcpy (_out_buffer + 1, group_msg.data (), group_size);
            memcpy (_out_buffer + 1 + group_size, body_msg.data (), body_size);
        }

        rc = group_msg.close ();
        errno_assert (rc == 0);

        body_msg.close ();
        errno_assert (rc == 0);

#ifdef ZMQ_HAVE_WINDOWS
        rc = sendto (_fd, _out_buffer, static_cast<int> (size), 0, _out_address,
                     _out_address_len);
#elif defined ZMQ_HAVE_VXWORKS
        rc = sendto (_fd, reinterpret_cast<caddr_t> (_out_buffer), size, 0,
                     (sockaddr *) _out_address, _out_address_len);
#else
        rc = sendto (_fd, _out_buffer, size, 0, _out_address, _out_address_len);
#endif
        if (rc < 0) {
#ifdef ZMQ_HAVE_WINDOWS
            if (WSAGetLastError () != WSAEWOULDBLOCK) {
                assert_success_or_recoverable (_fd, rc);
                error (connection_error);
            }
#else
            if (rc != EWOULDBLOCK) {
                assert_success_or_recoverable (_fd, rc);
                error (connection_error);
            }
#endif
        }
    } else {
        reset_pollout (_handle);
    }
}

const zmq::endpoint_uri_pair_t &zmq::udp_engine_t::get_endpoint () const
{
    return _empty_endpoint;
}

void zmq::udp_engine_t::restart_output ()
{
    //  If we don't support send we just drop all messages
    if (!_send_enabled) {
        msg_t msg;
        while (_session->pull_msg (&msg) == 0)
            msg.close ();
    } else {
        set_pollout (_handle);
        out_event ();
    }
}

void zmq::udp_engine_t::in_event ()
{
    sockaddr_storage in_address;
    zmq_socklen_t in_addrlen =
      static_cast<zmq_socklen_t> (sizeof (sockaddr_storage));

    const int nbytes =
      recvfrom (_fd, _in_buffer, MAX_UDP_MSG, 0,
                reinterpret_cast<sockaddr *> (&in_address), &in_addrlen);

    if (nbytes < 0) {
#ifdef ZMQ_HAVE_WINDOWS
        if (WSAGetLastError () != WSAEWOULDBLOCK) {
            assert_success_or_recoverable (_fd, nbytes);
            error (connection_error);
        }
#else
        if (nbytes != EWOULDBLOCK) {
            assert_success_or_recoverable (_fd, nbytes);
            error (connection_error);
        }
#endif
        return;
    }

    int rc;
    int body_size;
    int body_offset;
    msg_t msg;

    if (_options.raw_socket) {
        zmq_assert (in_address.ss_family == AF_INET);
        sockaddr_to_msg (&msg, reinterpret_cast<sockaddr_in *> (&in_address));

        body_size = nbytes;
        body_offset = 0;
    } else {
        // TODO in out_event, the group size is an *unsigned* char. what is
        // the maximum value?
        const char *group_buffer = _in_buffer + 1;
        const int group_size = _in_buffer[0];

        rc = msg.init_size (group_size);
        errno_assert (rc == 0);
        msg.set_flags (msg_t::more);
        memcpy (msg.data (), group_buffer, group_size);

        //  This doesn't fit, just ingore
        if (nbytes - 1 < group_size)
            return;

        body_size = nbytes - 1 - group_size;
        body_offset = 1 + group_size;
    }
    // Push group description to session
    rc = _session->push_msg (&msg);
    errno_assert (rc == 0 || (rc == -1 && errno == EAGAIN));

    //  Group description message doesn't fit in the pipe, drop
    if (rc != 0) {
        rc = msg.close ();
        errno_assert (rc == 0);

        reset_pollin (_handle);
        return;
    }

    rc = msg.close ();
    errno_assert (rc == 0);
    rc = msg.init_size (body_size);
    errno_assert (rc == 0);
    memcpy (msg.data (), _in_buffer + body_offset, body_size);

    // Push message body to session
    rc = _session->push_msg (&msg);
    // Message body doesn't fit in the pipe, drop and reset session state
    if (rc != 0) {
        rc = msg.close ();
        errno_assert (rc == 0);

        _session->reset ();
        reset_pollin (_handle);
        return;
    }

    rc = msg.close ();
    errno_assert (rc == 0);
    _session->flush ();
}

bool zmq::udp_engine_t::restart_input ()
{
    if (_recv_enabled) {
        set_pollin (_handle);
        in_event ();
    }

    return true;
}