pgm_socket.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"
#include "platform.hpp"

#ifdef ZMQ_HAVE_OPENPGM

#ifdef ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#endif

#ifdef ZMQ_HAVE_LINUX
#include <poll.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <string>

#include "options.hpp"
#include "pgm_socket.hpp"
#include "config.hpp"
#include "err.hpp"
#include "random.hpp"
#include "stdint.hpp"

#ifndef MSG_ERRQUEUE
#define MSG_ERRQUEUE 0x2000
#endif

zmq::pgm_socket_t::pgm_socket_t (bool receiver_, const options_t &options_) :
    sock (NULL),
    options (options_),
    receiver (receiver_),
    pgm_msgv (NULL),
    pgm_msgv_len (0),
    nbytes_rec (0),
    nbytes_processed (0),
    pgm_msgv_processed (0)
{
}

//  Resolve PGM socket address.
//  network_ of the form <interface & multicast group decls>:<IP port>
//  e.g. eth0;239.192.0.1:7500
//       link-local;224.250.0.1,224.250.0.2;224.250.0.3:8000
//       ;[fe80::1%en0]:7500
int zmq::pgm_socket_t::init_address (const char *network_,
    struct pgm_addrinfo_t **res, uint16_t *port_number)
{
    //  Parse port number, start from end for IPv6
    const char *port_delim = strrchr (network_, ':');
    if (!port_delim) {
        errno = EINVAL;
        return -1;
    }

    *port_number = atoi (port_delim + 1);

    char network [256];
    if (port_delim - network_ >= (int) sizeof (network) - 1) {
        errno = EINVAL;
        return -1;
    }
    memset (network, '\0', sizeof (network));
    memcpy (network, network_, port_delim - network_);

    pgm_error_t *pgm_error = NULL;
    struct pgm_addrinfo_t hints;

    memset (&hints, 0, sizeof (hints));
    hints.ai_family = AF_UNSPEC;
    if (!pgm_getaddrinfo (network, NULL, res, &pgm_error)) {

        //  Invalid parameters don't set pgm_error_t.
        zmq_assert (pgm_error != NULL);
        if (pgm_error->domain == PGM_ERROR_DOMAIN_IF &&

              //  NB: cannot catch EAI_BADFLAGS.
            ( pgm_error->code != PGM_ERROR_SERVICE &&
              pgm_error->code != PGM_ERROR_SOCKTNOSUPPORT)) {

            //  User, host, or network configuration or transient error.
            pgm_error_free (pgm_error);
            errno = EINVAL;
            return -1;
        }

        //  Fatal OpenPGM internal error.
        zmq_assert (false);
    }
    return 0;
}

//  Create, bind and connect PGM socket.
int zmq::pgm_socket_t::init (bool udp_encapsulation_, const char *network_)
{
    //  Can not open transport before destroying old one.
    zmq_assert (sock == NULL);
    zmq_assert (options.rate > 0);

    //  Zero counter used in msgrecv.
    nbytes_rec = 0;
    nbytes_processed = 0;
    pgm_msgv_processed = 0;

    uint16_t port_number;
    struct pgm_addrinfo_t *res = NULL;
    sa_family_t sa_family;

    pgm_error_t *pgm_error = NULL;

    if (init_address(network_, &res, &port_number) < 0) {
        goto err_abort;
    }

    zmq_assert (res != NULL);

    //  Pick up detected IP family.
    sa_family = res->ai_send_addrs[0].gsr_group.ss_family;

    //  Create IP/PGM or UDP/PGM socket.
    if (udp_encapsulation_) {
        if (!pgm_socket (&sock, sa_family, SOCK_SEQPACKET, IPPROTO_UDP,
              &pgm_error)) {

            //  Invalid parameters don't set pgm_error_t.
            zmq_assert (pgm_error != NULL);
            if (pgm_error->domain == PGM_ERROR_DOMAIN_SOCKET && (
                  pgm_error->code != PGM_ERROR_BADF &&
                  pgm_error->code != PGM_ERROR_FAULT &&
                  pgm_error->code != PGM_ERROR_NOPROTOOPT &&
                  pgm_error->code != PGM_ERROR_FAILED))

                //  User, host, or network configuration or transient error.
                goto err_abort;

            //  Fatal OpenPGM internal error.
            zmq_assert (false);
        }

        //  All options are of data type int
        const int encapsulation_port = port_number;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_UDP_ENCAP_UCAST_PORT,
                &encapsulation_port, sizeof (encapsulation_port)))
            goto err_abort;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_UDP_ENCAP_MCAST_PORT,
                &encapsulation_port, sizeof (encapsulation_port)))
            goto err_abort;
    }
    else {
        if (!pgm_socket (&sock, sa_family, SOCK_SEQPACKET, IPPROTO_PGM,
              &pgm_error)) {

            //  Invalid parameters don't set pgm_error_t.
            zmq_assert (pgm_error != NULL);
            if (pgm_error->domain == PGM_ERROR_DOMAIN_SOCKET && (
                  pgm_error->code != PGM_ERROR_BADF &&
                  pgm_error->code != PGM_ERROR_FAULT &&
                  pgm_error->code != PGM_ERROR_NOPROTOOPT &&
                  pgm_error->code != PGM_ERROR_FAILED))

                //  User, host, or network configuration or transient error.
                goto err_abort;

            //  Fatal OpenPGM internal error.
            zmq_assert (false);
        }
    }

    {
        const int rcvbuf = (int) options.rcvbuf;
        if (rcvbuf >= 0) {
            if (!pgm_setsockopt (sock, SOL_SOCKET, SO_RCVBUF, &rcvbuf,
                  sizeof (rcvbuf)))
                goto err_abort;
        }

        const int sndbuf = (int) options.sndbuf;
        if (sndbuf >= 0) {
            if (!pgm_setsockopt (sock, SOL_SOCKET, SO_SNDBUF, &sndbuf,
                  sizeof (sndbuf)))
                goto err_abort;
        }

        const int max_tpdu = (int) options.multicast_maxtpdu;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_MTU, &max_tpdu,
              sizeof (max_tpdu)))
            goto err_abort;
    }

    if (receiver) {
        const int recv_only        = 1,
                  rxw_max_tpdu     = (int) options.multicast_maxtpdu,
                  rxw_sqns         = compute_sqns (rxw_max_tpdu),
                  peer_expiry      = pgm_secs (300),
                  spmr_expiry      = pgm_msecs (25),
                  nak_bo_ivl       = pgm_msecs (50),
                  nak_rpt_ivl      = pgm_msecs (200),
                  nak_rdata_ivl    = pgm_msecs (200),
                  nak_data_retries = 50,
                  nak_ncf_retries  = 50;

        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_RECV_ONLY, &recv_only,
                sizeof (recv_only)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_RXW_SQNS, &rxw_sqns,
                sizeof (rxw_sqns)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_PEER_EXPIRY, &peer_expiry,
                sizeof (peer_expiry)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_SPMR_EXPIRY, &spmr_expiry,
                sizeof (spmr_expiry)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_NAK_BO_IVL, &nak_bo_ivl,
                sizeof (nak_bo_ivl)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_NAK_RPT_IVL, &nak_rpt_ivl,
                sizeof (nak_rpt_ivl)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_NAK_RDATA_IVL,
                &nak_rdata_ivl, sizeof (nak_rdata_ivl)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_NAK_DATA_RETRIES,
                &nak_data_retries, sizeof (nak_data_retries)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_NAK_NCF_RETRIES,
                &nak_ncf_retries, sizeof (nak_ncf_retries)))
            goto err_abort;
    }
    else {
        const int send_only        = 1,
                  max_rte      = (int) ((options.rate * 1000) / 8),
                  txw_max_tpdu     = (int) options.multicast_maxtpdu,
                  txw_sqns         = compute_sqns (txw_max_tpdu),
                  ambient_spm      = pgm_secs (30),
                  heartbeat_spm[]  = { pgm_msecs (100),
                                       pgm_msecs (100),
                                       pgm_msecs (100),
                                       pgm_msecs (100),
                                       pgm_msecs (1300),
                                       pgm_secs  (7),
                                       pgm_secs  (16),
                                       pgm_secs  (25),
                                       pgm_secs  (30) };

        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_SEND_ONLY,
                &send_only, sizeof (send_only)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_ODATA_MAX_RTE,
                &max_rte, sizeof (max_rte)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_TXW_SQNS,
                &txw_sqns, sizeof (txw_sqns)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_AMBIENT_SPM,
                &ambient_spm, sizeof (ambient_spm)) ||
            !pgm_setsockopt (sock, IPPROTO_PGM, PGM_HEARTBEAT_SPM,
                &heartbeat_spm, sizeof (heartbeat_spm)))
            goto err_abort;
    }

    //  PGM transport GSI.
    struct pgm_sockaddr_t addr;

    memset (&addr, 0, sizeof(addr));
    addr.sa_port = port_number;
    addr.sa_addr.sport = DEFAULT_DATA_SOURCE_PORT;

    //  Create random GSI.
    uint32_t buf [2];
    buf [0] = generate_random ();
    buf [1] = generate_random ();
    if (!pgm_gsi_create_from_data (&addr.sa_addr.gsi, (uint8_t*) buf, 8))
        goto err_abort;


    //  Bind a transport to the specified network devices.
    struct pgm_interface_req_t if_req;
    memset (&if_req, 0, sizeof(if_req));
    if_req.ir_interface = res->ai_recv_addrs[0].gsr_interface;
    if_req.ir_scope_id  = 0;
    if (AF_INET6 == sa_family) {
        struct sockaddr_in6 sa6;
        memcpy (&sa6, &res->ai_recv_addrs[0].gsr_group, sizeof (sa6));
        if_req.ir_scope_id = sa6.sin6_scope_id;
    }
    if (!pgm_bind3 (sock, &addr, sizeof (addr), &if_req, sizeof (if_req),
          &if_req, sizeof (if_req), &pgm_error)) {

        //  Invalid parameters don't set pgm_error_t.
        zmq_assert (pgm_error != NULL);
        if ((pgm_error->domain == PGM_ERROR_DOMAIN_SOCKET ||
             pgm_error->domain == PGM_ERROR_DOMAIN_IF) && (
             pgm_error->code != PGM_ERROR_INVAL &&
             pgm_error->code != PGM_ERROR_BADF &&
             pgm_error->code != PGM_ERROR_FAULT))

            //  User, host, or network configuration or transient error.
            goto err_abort;

        //  Fatal OpenPGM internal error.
        zmq_assert (false);
    }

    //  Join IP multicast groups.
    for (unsigned i = 0; i < res->ai_recv_addrs_len; i++) {
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_JOIN_GROUP,
              &res->ai_recv_addrs [i], sizeof (struct group_req)))
            goto err_abort;
    }
    if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_SEND_GROUP,
          &res->ai_send_addrs [0], sizeof (struct group_req)))
        goto err_abort;

    pgm_freeaddrinfo (res);
    res = NULL;

    //  Set IP level parameters.
    {
        // Multicast loopback disabled by default
        const int multicast_loop = 0;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_MULTICAST_LOOP,
              &multicast_loop, sizeof (multicast_loop)))
            goto err_abort;

        const int multicast_hops = options.multicast_hops;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_MULTICAST_HOPS,
                &multicast_hops, sizeof (multicast_hops)))
            goto err_abort;

        //  Expedited Forwarding PHB for network elements, no ECN.
        //  Ignore return value due to varied runtime support.
        const int dscp = 0x2e << 2;
        if (AF_INET6 != sa_family)
            pgm_setsockopt (sock, IPPROTO_PGM, PGM_TOS,
               &dscp, sizeof (dscp));

        const int nonblocking = 1;
        if (!pgm_setsockopt (sock, IPPROTO_PGM, PGM_NOBLOCK,
              &nonblocking, sizeof (nonblocking)))
            goto err_abort;
    }

    //  Connect PGM transport to start state machine.
    if (!pgm_connect (sock, &pgm_error)) {

        //  Invalid parameters don't set pgm_error_t.
        zmq_assert (pgm_error != NULL);
        goto err_abort;
    }

    //  For receiver transport preallocate pgm_msgv array.
    if (receiver) {
        zmq_assert (in_batch_size > 0);
        size_t max_tsdu_size = get_max_tsdu_size ();
        pgm_msgv_len = (int) in_batch_size / max_tsdu_size;
        if ((int) in_batch_size % max_tsdu_size)
            pgm_msgv_len++;
        zmq_assert (pgm_msgv_len);

        pgm_msgv = (pgm_msgv_t*) malloc (sizeof (pgm_msgv_t) * pgm_msgv_len);
        alloc_assert (pgm_msgv);
    }

    return 0;

err_abort:
    if (sock != NULL) {
        pgm_close (sock, FALSE);
        sock = NULL;
    }
    if (res != NULL) {
        pgm_freeaddrinfo (res);
        res = NULL;
    }
    if (pgm_error != NULL) {
        pgm_error_free (pgm_error);
        pgm_error = NULL;
    }
    errno = EINVAL;
    return -1;
}

zmq::pgm_socket_t::~pgm_socket_t ()
{
    if (pgm_msgv)
        free (pgm_msgv);
    if (sock)
        pgm_close (sock, TRUE);
}

//  Get receiver fds. receive_fd_ is signaled for incoming packets,
//  waiting_pipe_fd_ is signaled for state driven events and data.
void zmq::pgm_socket_t::get_receiver_fds (fd_t *receive_fd_,
    fd_t *waiting_pipe_fd_)
{
    socklen_t socklen;
    bool rc;

    zmq_assert (receive_fd_);
    zmq_assert (waiting_pipe_fd_);

    socklen = sizeof (*receive_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_RECV_SOCK, receive_fd_,
        &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*receive_fd_));

    socklen = sizeof (*waiting_pipe_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_PENDING_SOCK, waiting_pipe_fd_,
        &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*waiting_pipe_fd_));
}

//  Get fds and store them into user allocated memory.
//  send_fd is for non-blocking send wire notifications.
//  receive_fd_ is for incoming back-channel protocol packets.
//  rdata_notify_fd_ is raised for waiting repair transmissions.
//  pending_notify_fd_ is for state driven events.
void zmq::pgm_socket_t::get_sender_fds (fd_t *send_fd_, fd_t *receive_fd_,
    fd_t *rdata_notify_fd_, fd_t *pending_notify_fd_)
{
    socklen_t socklen;
    bool rc;

    zmq_assert (send_fd_);
    zmq_assert (receive_fd_);
    zmq_assert (rdata_notify_fd_);
    zmq_assert (pending_notify_fd_);

    socklen = sizeof (*send_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_SEND_SOCK, send_fd_, &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*receive_fd_));

    socklen = sizeof (*receive_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_RECV_SOCK, receive_fd_,
        &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*receive_fd_));

    socklen = sizeof (*rdata_notify_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_REPAIR_SOCK, rdata_notify_fd_,
        &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*rdata_notify_fd_));

    socklen = sizeof (*pending_notify_fd_);
    rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_PENDING_SOCK,
        pending_notify_fd_, &socklen);
    zmq_assert (rc);
    zmq_assert (socklen == sizeof (*pending_notify_fd_));
}

//  Send one APDU, transmit window owned memory.
//  data_len_ must be less than one TPDU.
size_t zmq::pgm_socket_t::send (unsigned char *data_, size_t data_len_)
{
    size_t nbytes = 0;

    const int status = pgm_send (sock, data_, data_len_, &nbytes);

    //  We have to write all data as one packet.
    if (nbytes > 0) {
        zmq_assert (status == PGM_IO_STATUS_NORMAL);
        zmq_assert (nbytes == data_len_);
    }
    else {
        zmq_assert (status == PGM_IO_STATUS_RATE_LIMITED ||
            status == PGM_IO_STATUS_WOULD_BLOCK);

        if (status == PGM_IO_STATUS_RATE_LIMITED)
            errno = ENOMEM;
        else
            errno = EBUSY;
    }

    //  Save return value.
    last_tx_status = status;

    return nbytes;
}

long zmq::pgm_socket_t::get_rx_timeout ()
{
    if (last_rx_status != PGM_IO_STATUS_RATE_LIMITED &&
          last_rx_status != PGM_IO_STATUS_TIMER_PENDING)
        return -1;

    struct timeval tv;
    socklen_t optlen = sizeof (tv);
    const bool rc = pgm_getsockopt (sock, IPPROTO_PGM,
        last_rx_status == PGM_IO_STATUS_RATE_LIMITED ? PGM_RATE_REMAIN :
        PGM_TIME_REMAIN, &tv, &optlen);
    zmq_assert (rc);

    const long timeout = (tv.tv_sec * 1000) + (tv.tv_usec / 1000);

    return timeout;
}

long zmq::pgm_socket_t::get_tx_timeout ()
{
    if (last_tx_status != PGM_IO_STATUS_RATE_LIMITED)
        return -1;

    struct timeval tv;
    socklen_t optlen = sizeof (tv);
    const bool rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_RATE_REMAIN, &tv,
        &optlen);
    zmq_assert (rc);

    const long timeout = (tv.tv_sec * 1000) + (tv.tv_usec / 1000);

    return timeout;
}

//  Return max TSDU size without fragmentation from current PGM transport.
size_t zmq::pgm_socket_t::get_max_tsdu_size ()
{
    int max_tsdu = 0;
    socklen_t optlen = sizeof (max_tsdu);

    bool rc = pgm_getsockopt (sock, IPPROTO_PGM, PGM_MSS, &max_tsdu, &optlen);
    zmq_assert (rc);
    zmq_assert (optlen == sizeof (max_tsdu));
    return (size_t) max_tsdu;
}

//  pgm_recvmsgv is called to fill the pgm_msgv array up to  pgm_msgv_len.
//  In subsequent calls data from pgm_msgv structure are returned.
ssize_t zmq::pgm_socket_t::receive (void **raw_data_, const pgm_tsi_t **tsi_)
{
    size_t raw_data_len = 0;

    //  We just sent all data from pgm_transport_recvmsgv up
    //  and have to return 0 that another engine in this thread is scheduled.
    if (nbytes_rec == nbytes_processed && nbytes_rec > 0) {

        //  Reset all the counters.
        nbytes_rec = 0;
        nbytes_processed = 0;
        pgm_msgv_processed = 0;
        errno = EAGAIN;
        return 0;
    }

    //  If we have are going first time or if we have processed all pgm_msgv_t
    //  structure previously read from the pgm socket.
    if (nbytes_rec == nbytes_processed) {

        //  Check program flow.
        zmq_assert (pgm_msgv_processed == 0);
        zmq_assert (nbytes_processed == 0);
        zmq_assert (nbytes_rec == 0);

        //  Receive a vector of Application Protocol Domain Unit's (APDUs)
        //  from the transport.
        pgm_error_t *pgm_error = NULL;

        const int status = pgm_recvmsgv (sock, pgm_msgv,
            pgm_msgv_len, MSG_ERRQUEUE, &nbytes_rec, &pgm_error);

        //  Invalid parameters.
        zmq_assert (status != PGM_IO_STATUS_ERROR);

        last_rx_status = status;

        //  In a case when no ODATA/RDATA fired POLLIN event (SPM...)
        //  pgm_recvmsg returns PGM_IO_STATUS_TIMER_PENDING.
        if (status == PGM_IO_STATUS_TIMER_PENDING) {

            zmq_assert (nbytes_rec == 0);

            //  In case if no RDATA/ODATA caused POLLIN 0 is
            //  returned.
            nbytes_rec = 0;
            errno = EBUSY;
            return 0;
        }

        //  Send SPMR, NAK, ACK is rate limited.
        if (status == PGM_IO_STATUS_RATE_LIMITED) {

            zmq_assert (nbytes_rec == 0);

            //  In case if no RDATA/ODATA caused POLLIN 0 is returned.
            nbytes_rec = 0;
            errno = ENOMEM;
            return 0;
        }

        //  No peers and hence no incoming packets.
        if (status == PGM_IO_STATUS_WOULD_BLOCK) {

            zmq_assert (nbytes_rec == 0);

            //  In case if no RDATA/ODATA caused POLLIN 0 is returned.
            nbytes_rec = 0;
            errno = EAGAIN;
            return 0;
        }

        //  Data loss.
        if (status == PGM_IO_STATUS_RESET) {

            struct pgm_sk_buff_t* skb = pgm_msgv [0].msgv_skb [0];

            //  Save lost data TSI.
            *tsi_ = &skb->tsi;
            nbytes_rec = 0;

            //  In case of dala loss -1 is returned.
            errno = EINVAL;
            pgm_free_skb (skb);
            return -1;
        }

        zmq_assert (status == PGM_IO_STATUS_NORMAL);
    }
    else
    {
        zmq_assert (pgm_msgv_processed <= pgm_msgv_len);
    }

    // Zero byte payloads are valid in PGM, but not 0MQ protocol.
    zmq_assert (nbytes_rec > 0);

    // Only one APDU per pgm_msgv_t structure is allowed.
    zmq_assert (pgm_msgv [pgm_msgv_processed].msgv_len == 1);

    struct pgm_sk_buff_t* skb =
        pgm_msgv [pgm_msgv_processed].msgv_skb [0];

    //  Take pointers from pgm_msgv_t structure.
    *raw_data_ = skb->data;
    raw_data_len = skb->len;

    //  Save current TSI.
    *tsi_ = &skb->tsi;

    //  Move the the next pgm_msgv_t structure.
    pgm_msgv_processed++;
    zmq_assert (pgm_msgv_processed <= pgm_msgv_len);
    nbytes_processed +=raw_data_len;

    return raw_data_len;
}

void zmq::pgm_socket_t::process_upstream ()
{
    pgm_msgv_t dummy_msg;

    size_t dummy_bytes = 0;
    pgm_error_t *pgm_error = NULL;

    const int status = pgm_recvmsgv (sock, &dummy_msg,
        1, MSG_ERRQUEUE, &dummy_bytes, &pgm_error);

    //  Invalid parameters.
    zmq_assert (status != PGM_IO_STATUS_ERROR);

    //  No data should be returned.
    zmq_assert (dummy_bytes == 0 && (status == PGM_IO_STATUS_TIMER_PENDING ||
        status == PGM_IO_STATUS_RATE_LIMITED ||
        status == PGM_IO_STATUS_WOULD_BLOCK));

    last_rx_status = status;

    if (status == PGM_IO_STATUS_TIMER_PENDING)
        errno = EBUSY;
    else
    if (status == PGM_IO_STATUS_RATE_LIMITED)
        errno = ENOMEM;
    else
        errno = EAGAIN;
}

int zmq::pgm_socket_t::compute_sqns (int tpdu_)
{
    //  Convert rate into B/ms.
    uint64_t rate = uint64_t (options.rate) / 8;

    //  Compute the size of the buffer in bytes.
    uint64_t size = uint64_t (options.recovery_ivl) * rate;

    //  Translate the size into number of packets.
    uint64_t sqns = size / tpdu_;

    //  Buffer should be able to hold at least one packet.
    if (sqns == 0)
        sqns = 1;

    return (int) sqns;
}

#endif