/*
 * Cisco router simulation platform.
 * Copyright (c) 2005,2006 Christophe Fillot (cf@utc.fr)
 *
 * Network Input/Output Abstraction Layer.
 */

/* By default, Cygwin supports only 64 FDs with select()! */
#ifdef __CYGWIN__
#define FD_SETSIZE 1024
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <ctype.h>
#include <time.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <pthread.h>

#ifdef __linux__
#include <net/if.h>
#include <linux/if_tun.h>
#endif

#include "net.h"
#include "net_io.h"

/* Free a NetIO descriptor */
static int netio_free (void *data, void *arg);
#if 0
/* NIO RX listener */
static pthread_mutex_t netio_rxl_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t netio_rxq_mutex = PTHREAD_MUTEX_INITIALIZER;
static struct netio_rx_listener *netio_rxl_list = NULL;
static struct netio_rx_listener *netio_rxl_add_list = NULL;
static netio_desc_t *netio_rxl_remove_list = NULL;
static pthread_t netio_rxl_thread;
static pthread_cond_t netio_rxl_cond;

#define NETIO_RXL_LOCK()   pthread_mutex_lock(&netio_rxl_mutex);
#define NETIO_RXL_UNLOCK() pthread_mutex_unlock(&netio_rxl_mutex);

#define NETIO_RXQ_LOCK()   pthread_mutex_lock(&netio_rxq_mutex);
#define NETIO_RXQ_UNLOCK() pthread_mutex_unlock(&netio_rxq_mutex);
#endif

/* NetIO type */
typedef struct {
    char *name;
    char *desc;
} netio_type_t;

/* NETIO types (must follow the enum definition) */
static netio_type_t netio_types[NETIO_TYPE_MAX] = {
    {"unix", "UNIX local sockets"},
    {"vde", "Virtual Distributed Ethernet / UML switch"},
    {"tap", "Linux/FreeBSD TAP device"},
    {"udp", "UDP sockets"},
    {"tcp_cli", "TCP client"},
    {"tcp_ser", "TCP server"},
#ifdef LINUX_ETH
    {"linux_eth", "Linux Ethernet device"},
#endif
#ifdef GEN_ETH
    {"gen_eth", "Generic Ethernet device (PCAP)"},
#endif
    {"fifo", "FIFO (intra-hypervisor)"},
    {"null", "Null device"},
};

/* Get NETIO type given a description */
int netio_get_type (char *type)
{
    int i;

    for (i = 0; i < NETIO_TYPE_MAX; i++)
        if (!strcmp (type, netio_types[i].name))
            return (i);

    return (-1);
}

/* Show the NETIO types */
void netio_show_types (void)
{
    int i;

    printf ("Available NETIO types:\n");

    for (i = 0; i < NETIO_TYPE_MAX; i++)
        printf ("  * %-10s : %s\n", netio_types[i].name, netio_types[i].desc);

    printf ("\n");
}

/* Create a new NetIO descriptor */
static netio_desc_t *netio_create (char *name)
{
    netio_desc_t *nio;

    if (!(nio = malloc (sizeof (*nio))))
        return NULL;

    /* setup as a NULL descriptor */
    memset (nio, 0, sizeof (*nio));
    nio->type = NETIO_TYPE_NULL;

    /* save name for registry */
    if (!(nio->name = strdup (name))) {
        free (nio);
        return NULL;
    }

    return nio;
}

/* Send a packet through a NetIO descriptor */
ssize_t netio_send (netio_desc_t * nio, void *pkt, size_t len)
{

    if (!nio)
        return (-1);

    if (nio->debug) {
        printf ("NIO %s: sending a packet of %lu bytes:\n", nio->name,
            (u_long) len);
        mem_dump (stdout, pkt, len);
    }

    return (nio->send (nio->dptr, pkt, len));
}

/* Receive a packet through a NetIO descriptor */
ssize_t netio_recv (netio_desc_t * nio, void *pkt, size_t max_len)
{
    ssize_t len;

    if (!nio)
        return (-1);

    /* Receive the packet */
    if ((len = nio->recv (nio->dptr, pkt, max_len)) <= 0)
        return (-1);

    if (nio->debug) {
        printf ("NIO %s: receiving a packet of %ld bytes:\n", nio->name,
            (long) len);
        mem_dump (stdout, pkt, len);
    }

    return (len);
}

/* Get a NetIO FD */
int netio_get_fd (netio_desc_t * nio)
{
    int fd = -1;

    switch (nio->type) {
        //case NETIO_TYPE_UNIX:
        //   fd = nio->u.nud.fd;
        //   break;
        //case NETIO_TYPE_VDE:
        //   fd = nio->u.nvd.data_fd;
        //    break;
    case NETIO_TYPE_TAP:
        fd = nio->u.ntd.fd;
        break;
        //case NETIO_TYPE_TCP_CLI:
        //case NETIO_TYPE_TCP_SER:
        //case NETIO_TYPE_UDP:
        //   fd = nio->u.nid.fd;
        //   break;
//#ifdef LINUX_ETH
//      case NETIO_TYPE_LINUX_ETH:
//         fd = nio->u.nled.fd;
//         break;
//#endif
    }

    return (fd);
}

#if 0
/*
 * =========================================================================
 * UNIX sockets
 * =========================================================================
 */

/* Create an UNIX socket */
static int netio_unix_create_socket (netio_unix_desc_t * nud)
{
    struct sockaddr_un local_sock;

    if ((nud->fd = socket (AF_UNIX, SOCK_DGRAM, 0)) == -1) {
        perror ("netio_unix: socket");
        return (-1);
    }

    memset (&local_sock, 0, sizeof (local_sock));
    local_sock.sun_family = AF_UNIX;
    strcpy (local_sock.sun_path, nud->local_filename);

    if (bind (nud->fd, (struct sockaddr *) &local_sock,
            sizeof (local_sock)) == -1) {
        perror ("netio_unix: bind");
        return (-1);
    }

    return (nud->fd);
}

/* Free a NetIO unix descriptor */
static void netio_unix_free (netio_unix_desc_t * nud)
{
    if (nud->fd != -1)
        close (nud->fd);

    if (nud->local_filename) {
        unlink (nud->local_filename);
        free (nud->local_filename);
    }
}

/* Allocate a new NetIO UNIX descriptor */
static int netio_unix_create (netio_unix_desc_t * nud, char *local,
    char *remote)
{
    memset (nud, 0, sizeof (*nud));
    nud->fd = -1;

    /* check lengths */
    if ((strlen (local) >= sizeof (nud->remote_sock.sun_path))
        || (strlen (remote) >= sizeof (nud->remote_sock.sun_path)))
        goto nomem_error;

    if (!(nud->local_filename = strdup (local)))
        goto nomem_error;

    if (netio_unix_create_socket (nud) == -1)
        return (-1);

    /* prepare the remote info */
    nud->remote_sock.sun_family = AF_UNIX;
    strcpy (nud->remote_sock.sun_path, remote);
    return (0);

  nomem_error:
    fprintf (stderr,
        "netio_unix_create: " "invalid file size or insufficient memory\n");
    return (-1);
}

/* Write a packet to an UNIX socket */
static ssize_t netio_unix_send (netio_unix_desc_t * nud, void *pkt,
    size_t pkt_len)
{
    return (sendto (nud->fd, pkt, pkt_len, 0,
            (struct sockaddr *) &nud->remote_sock,
            sizeof (&nud->remote_sock)));
}

/* Receive a packet from an UNIX socket */
static ssize_t netio_unix_recv (netio_unix_desc_t * nud, void *pkt,
    size_t max_len)
{
    return (recvfrom (nud->fd, pkt, max_len, 0, NULL, NULL));
}

/* Save the NIO configuration */
static void netio_unix_save_cfg (netio_desc_t * nio, FILE * fd)
{
    netio_unix_desc_t *nud = nio->dptr;
    fprintf (fd, "nio create_unix %s %s %s\n", nio->name, nud->local_filename,
        nud->remote_sock.sun_path);
}

/* Create a new NetIO descriptor with UNIX method */
netio_desc_t *netio_desc_create_unix (char *nio_name, char *local,
    char *remote)
{
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    if (netio_unix_create (&nio->u.nud, local, remote) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_UNIX;
    nio->send = (void *) netio_unix_send;
    nio->recv = (void *) netio_unix_recv;
    nio->save_cfg = netio_unix_save_cfg;
    nio->dptr = &nio->u.nud;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}

/*
 * =========================================================================
 * VDE (Virtual Distributed Ethernet) interface
 * =========================================================================
 */

/* Free a NetIO VDE descriptor */
static void netio_vde_free (netio_vde_desc_t * nvd)
{
    if (nvd->data_fd != -1)
        close (nvd->data_fd);

    if (nvd->ctrl_fd != -1)
        close (nvd->ctrl_fd);

    if (nvd->local_filename) {
        unlink (nvd->local_filename);
        free (nvd->local_filename);
    }
}

/* Create a new NetIO VDE descriptor */
static int netio_vde_create (netio_vde_desc_t * nvd, char *control,
    char *local)
{
    struct sockaddr_un ctrl_sock, tst;
    struct vde_request_v3 req;
    ssize_t len;
    int res;

    memset (nvd, 0, sizeof (*nvd));
    nvd->ctrl_fd = nvd->data_fd = -1;

    if ((strlen (control) >= sizeof (ctrl_sock.sun_path))
        || (strlen (local) >= sizeof (nvd->remote_sock.sun_path))) {
        fprintf (stderr, "netio_vde_create: bad filenames specified\n");
        return (-1);
    }

    /* Copy the local filename */
    if (!(nvd->local_filename = strdup (local))) {
        fprintf (stderr, "netio_vde_create: insufficient memory\n");
        return (-1);
    }

    /* Connect to the VDE switch controller */
    nvd->ctrl_fd = socket (AF_UNIX, SOCK_STREAM, 0);
    if (nvd->ctrl_fd < 0) {
        perror ("netio_vde_create: socket(control)");
        return (-1);
    }

    memset (&ctrl_sock, 0, sizeof (ctrl_sock));
    ctrl_sock.sun_family = AF_UNIX;
    strcpy (ctrl_sock.sun_path, control);

    res =
        connect (nvd->ctrl_fd, (struct sockaddr *) &ctrl_sock,
        sizeof (ctrl_sock));

    if (res < 0) {
        perror ("netio_vde_create: connect(control)");
        return (-1);
    }

    tst.sun_family = AF_UNIX;
    strcpy (tst.sun_path, local);

    /* Create the data connection */
    nvd->data_fd = socket (AF_UNIX, SOCK_DGRAM, 0);
    if (nvd->data_fd < 0) {
        perror ("netio_vde_create: socket(data)");
        return (-1);
    }

    if (bind (nvd->data_fd, (struct sockaddr *) &tst, sizeof (tst)) < 0) {
        perror ("netio_vde_create: bind(data)");
        return (-1);
    }

    /* Now, process to registration */
    memset (&req, 0, sizeof (req));
    req.sock.sun_family = AF_UNIX;
    strcpy (req.sock.sun_path, local);
    req.magic = VDE_SWITCH_MAGIC;
    req.version = VDE_SWITCH_VERSION;
    req.type = VDE_REQ_NEW_CONTROL;

    len = write (nvd->ctrl_fd, &req, sizeof (req));
    if (len != sizeof (req)) {
        perror ("netio_vde_create: write(req)");
        return (-1);
    }

    /* Read the remote socket descriptor */
    len = read (nvd->ctrl_fd, &nvd->remote_sock, sizeof (nvd->remote_sock));
    if (len != sizeof (nvd->remote_sock)) {
        perror ("netio_vde_create: read(req)");
        return (-1);
    }

    return (0);
}

/* Write a packet to a VDE data socket */
static ssize_t netio_vde_send (netio_vde_desc_t * nvd, void *pkt,
    size_t pkt_len)
{
    return (sendto (nvd->data_fd, pkt, pkt_len, 0,
            (struct sockaddr *) &nvd->remote_sock,
            sizeof (nvd->remote_sock)));
}

/* Receive a packet from a VDE socket */
static ssize_t netio_vde_recv (netio_vde_desc_t * nvd, void *pkt,
    size_t max_len)
{
    return (recvfrom (nvd->data_fd, pkt, max_len, 0, NULL, NULL));
}

/* Save the NIO configuration */
static void netio_vde_save_cfg (netio_desc_t * nio, FILE * fd)
{
    netio_vde_desc_t *nvd = nio->dptr;
    fprintf (fd, "nio create_vde %s %s %s\n", nio->name,
        nvd->remote_sock.sun_path, nvd->local_filename);
}

/* Create a new NetIO descriptor with VDE method */
netio_desc_t *netio_desc_create_vde (char *nio_name, char *control,
    char *local)
{
    netio_vde_desc_t *nvd;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nvd = &nio->u.nvd;

    if (netio_vde_create (nvd, control, local) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_VDE;
    nio->send = (void *) netio_vde_send;
    nio->recv = (void *) netio_vde_recv;
    nio->save_cfg = netio_vde_save_cfg;
    nio->dptr = &nio->u.nvd;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}
#endif
/*
 * =========================================================================
 * TAP devices
 * =========================================================================
 */

/* Free a NetIO TAP descriptor */
static void netio_tap_free (netio_tap_desc_t * ntd)
{
    if (ntd->fd != -1)
        close (ntd->fd);
}

/* Open a TAP device */
static int netio_tap_open (char *tap_devname)
{
#ifdef __linux__
    struct ifreq ifr;
    int fd, err;

    if ((fd = open ("/dev/net/tun", O_RDWR)) < 0)
        return (-1);

    memset (&ifr, 0, sizeof (ifr));

    /* Flags: IFF_TUN   - TUN device (no Ethernet headers)
     *        IFF_TAP   - TAP device
     *
     *        IFF_NO_PI - Do not provide packet information
     */
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
    if (*tap_devname)
        strncpy (ifr.ifr_name, tap_devname, IFNAMSIZ);

    if ((err = ioctl (fd, TUNSETIFF, (void *) &ifr)) < 0) {
        close (fd);
        return err;
    }

    strcpy (tap_devname, ifr.ifr_name);
    return (fd);
#else
    int i, fd = -1;

    if (*tap_devname) {
        fd = open (tap_devname, O_RDWR);
    } else {
        for (i = 0; i < 16; i++) {
            snprintf (tap_devname, NETIO_DEV_MAXLEN, "/dev/tap%d", i);

            if ((fd = open (tap_devname, O_RDWR)) >= 0)
                break;
        }
    }

    return (fd);
#endif
}

/* Allocate a new NetIO TAP descriptor */
static int netio_tap_create (netio_tap_desc_t * ntd, char *tap_name)
{
    if (strlen (tap_name) >= NETIO_DEV_MAXLEN) {
        fprintf (stderr,
            "netio_tap_create: bad TAP device string specified.\n");
        return (-1);
    }

    memset (ntd, 0, sizeof (*ntd));
    strcpy (ntd->filename, tap_name);
    ntd->fd = netio_tap_open (ntd->filename);

    if (ntd->fd == -1) {
        fprintf (stderr,
            "netio_tap_create: unable to open TAP device %s (%s)\n", tap_name,
            strerror (errno));
        return (-1);
    }
    /*SET NO BLOCKING */
    if (fcntl (ntd->fd, F_SETFL, O_NONBLOCK) == -1)
        printf ("Set file descriptor to non-blocking mode failed\n");

    return (0);
}

/* Write a packet to a TAP device */
static ssize_t netio_tap_send (netio_tap_desc_t * ntd, void *pkt,
    size_t pkt_len)
{
    return (write (ntd->fd, pkt, pkt_len));
}

/* Receive a packet through a TAP device */
static ssize_t netio_tap_recv (netio_tap_desc_t * ntd, void *pkt,
    size_t max_len)
{
    return (read (ntd->fd, pkt, max_len));
}

/* Create a new NetIO descriptor with TAP method */
netio_desc_t *netio_desc_create_tap (char *nio_name, char *tap_name)
{
    netio_tap_desc_t *ntd;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    ntd = &nio->u.ntd;

    if (netio_tap_create (ntd, tap_name) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_TAP;
    nio->send = (void *) netio_tap_send;
    nio->recv = (void *) netio_tap_recv;
    nio->dptr = &nio->u.ntd;

    return nio;
}

#if 0
/*
 * =========================================================================
 * TCP sockets
 * =========================================================================
 */

/* Free a NetIO TCP descriptor */
static void netio_tcp_free (netio_inet_desc_t * nid)
{
    if (nid->fd != -1)
        close (nid->fd);
}

/*
 * very simple protocol to send packets over tcp
 * 32 bits in network format - size of packet, then packet itself and so on.
 */
static ssize_t netio_tcp_send (netio_inet_desc_t * nid, void *pkt,
    size_t pkt_len)
{
    u_long l = htonl (pkt_len);

    if (write (nid->fd, &l, sizeof (l)) == -1)
        return (-1);

    return (write (nid->fd, pkt, pkt_len));
}

static ssize_t netio_tcp_recv (netio_inet_desc_t * nid, void *pkt,
    size_t max_len)
{
    u_long l;

    if (read (nid->fd, &l, sizeof (l)) != sizeof (l))
        return (-1);

    if (ntohl (l) > max_len)
        return (-1);

    return (read (nid->fd, pkt, ntohl (l)));
}

static int netio_tcp_cli_create (netio_inet_desc_t * nid, char *host,
    char *port)
{
    struct sockaddr_in serv;
    struct servent *sp;
    struct hostent *hp;

    if ((nid->fd = socket (PF_INET, SOCK_STREAM, 0)) < 0) {
        perror ("netio_tcp_cli_create: socket");
        return (-1);
    }

    memset (&serv, 0, sizeof (serv));
    serv.sin_family = AF_INET;

    if (atoi (port) == 0) {
        if (!(sp = getservbyname (port, "tcp"))) {
            fprintf (stderr,
                "netio_tcp_cli_create: port %s is neither "
                "number not service %s\n", port, strerror (errno));
            close (nid->fd);
            return (-1);
        }
        serv.sin_port = sp->s_port;
    } else
        serv.sin_port = htons (atoi (port));

    if (inet_addr (host) == INADDR_NONE) {
        if (!(hp = gethostbyname (host))) {
            fprintf (stderr, "netio_tcp_cli_create: no host %s\n", host);
            close (nid->fd);
            return (-1);
        }
        serv.sin_addr.s_addr = *hp->h_addr;
    } else
        serv.sin_addr.s_addr = inet_addr (host);

    if (connect (nid->fd, (struct sockaddr *) &serv, sizeof (serv)) < 0) {
        fprintf (stderr, "netio_tcp_cli_create: connect to %s:%s failed %s\n",
            host, port, strerror (errno));
        close (nid->fd);
        return (-1);
    }
    return (0);
}

/* Create a new NetIO descriptor with TCP_CLI method */
netio_desc_t *netio_desc_create_tcp_cli (char *nio_name, char *host,
    char *port)
{
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    if (netio_tcp_cli_create (&nio->u.nid, host, port) < 0) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_TCP_CLI;
    nio->send = (void *) netio_tcp_send;
    nio->recv = (void *) netio_tcp_recv;
    nio->dptr = &nio->u.nid;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}

static int netio_tcp_ser_create (netio_inet_desc_t * nid, char *port)
{
    struct sockaddr_in serv;
    struct servent *sp;
    int sock_fd;

    if ((sock_fd = socket (PF_INET, SOCK_STREAM, 0)) < 0) {
        perror ("netio_tcp_cli_create: socket\n");
        return (-1);
    }

    memset (&serv, 0, sizeof (serv));
    serv.sin_family = AF_INET;
    serv.sin_addr.s_addr = htonl (INADDR_ANY);

    if (atoi (port) == 0) {
        if (!(sp = getservbyname (port, "tcp"))) {
            fprintf (stderr,
                "netio_tcp_ser_create: port %s is neither "
                "number not service %s\n", port, strerror (errno));
            close (sock_fd);
            return (-1);
        }
        serv.sin_port = sp->s_port;
    } else
        serv.sin_port = htons (atoi (port));

    if (bind (sock_fd, (struct sockaddr *) &serv, sizeof (serv)) < 0) {
        fprintf (stderr, "netio_tcp_ser_create: bind %s failed %s\n", port,
            strerror (errno));
        close (sock_fd);
        return (-1);
    }

    if (listen (sock_fd, 1) < 0) {
        fprintf (stderr, "netio_tcp_ser_create: listen %s failed %s\n", port,
            strerror (errno));
        close (sock_fd);
        return (-1);
    }

    fprintf (stderr, "Waiting connection on port %s...\n", port);

    if ((nid->fd = accept (sock_fd, NULL, NULL)) < 0) {
        fprintf (stderr, "netio_tcp_ser_create: accept %s failed %s\n", port,
            strerror (errno));
        close (sock_fd);
        return (-1);
    }

    fprintf (stderr, "Connected\n");

    close (sock_fd);
    return (0);
}

/* Create a new NetIO descriptor with TCP_SER method */
netio_desc_t *netio_desc_create_tcp_ser (char *nio_name, char *port)
{
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    if (netio_tcp_ser_create (&nio->u.nid, port) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_TCP_SER;
    nio->send = (void *) netio_tcp_send;
    nio->recv = (void *) netio_tcp_recv;
    nio->dptr = &nio->u.nid;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}

/*
 * =========================================================================
 * UDP sockets
 * =========================================================================
 */

/* Free a NetIO UDP descriptor */
static void netio_udp_free (netio_inet_desc_t * nid)
{
    if (nid->remote_host) {
        free (nid->remote_host);
        nid->remote_host = NULL;
    }

    if (nid->fd != -1)
        close (nid->fd);
}

/* Write a packet to an UDP socket */
static ssize_t netio_udp_send (netio_inet_desc_t * nid, void *pkt,
    size_t pkt_len)
{
    return (send (nid->fd, pkt, pkt_len, 0));
}

/* Receive a packet from an UDP socket */
static ssize_t netio_udp_recv (netio_inet_desc_t * nid, void *pkt,
    size_t max_len)
{
    return (recvfrom (nid->fd, pkt, max_len, 0, NULL, NULL));
}

/* Save the NIO configuration */
static void netio_udp_save_cfg (netio_desc_t * nio, FILE * fd)
{
    netio_inet_desc_t *nid = nio->dptr;
    fprintf (fd, "nio create_udp %s %d %s %d\n", nio->name, nid->local_port,
        nid->remote_host, nid->remote_port);
}

/* Create a new NetIO descriptor with UDP method */
netio_desc_t *netio_desc_create_udp (char *nio_name, int local_port,
    char *remote_host, int remote_port)
{
    netio_inet_desc_t *nid;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nid = &nio->u.nid;
    nid->local_port = local_port;
    nid->remote_port = remote_port;

    if (!(nid->remote_host = strdup (remote_host))) {
        fprintf (stderr, "netio_desc_create_udp: insufficient memory\n");
        goto error;
    }

    if ((nid->fd = udp_connect (local_port, remote_host, remote_port)) < 0) {
        fprintf (stderr,
            "netio_desc_create_udp: unable to connect to %s:%d\n",
            remote_host, remote_port);
        goto error;
    }

    nio->type = NETIO_TYPE_UDP;
    nio->send = (void *) netio_udp_send;
    nio->recv = (void *) netio_udp_recv;
    nio->save_cfg = netio_udp_save_cfg;
    nio->dptr = &nio->u.nid;

    if (netio_record (nio) == -1)
        goto error;

    return nio;

  error:
    netio_free (nio, NULL);
    return NULL;
}

/*
 * =========================================================================
 * Linux RAW Ethernet driver
 * =========================================================================
 */
#ifdef LINUX_ETH
/* Free a NetIO raw ethernet descriptor */
static void netio_lnxeth_free (netio_lnxeth_desc_t * nled)
{
    if (nled->fd != -1)
        close (nled->fd);
}

/* Write a packet to a raw Ethernet socket */
static ssize_t netio_lnxeth_send (netio_lnxeth_desc_t * nled, void *pkt,
    size_t pkt_len)
{
    return (lnx_eth_send (nled->fd, nled->dev_id, pkt, pkt_len));
}

/* Receive a packet from an raw Ethernet socket */
static ssize_t netio_lnxeth_recv (netio_lnxeth_desc_t * nled, void *pkt,
    size_t max_len)
{
    return (lnx_eth_recv (nled->fd, pkt, max_len));
}

/* Save the NIO configuration */
static void netio_lnxeth_save_cfg (netio_desc_t * nio, FILE * fd)
{
    netio_lnxeth_desc_t *nled = nio->dptr;
    fprintf (fd, "nio create_linux_eth %s %s\n", nio->name, nled->dev_name);
}

/* Create a new NetIO descriptor with raw Ethernet method */
netio_desc_t *netio_desc_create_lnxeth (char *nio_name, char *dev_name)
{
    netio_lnxeth_desc_t *nled;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nled = &nio->u.nled;

    if (strlen (dev_name) >= NETIO_DEV_MAXLEN) {
        fprintf (stderr,
            "netio_desc_create_lnxeth: bad Ethernet device string "
            "specified.\n");
        netio_free (nio, NULL);
        return NULL;
    }

    strcpy (nled->dev_name, dev_name);

    nled->fd = lnx_eth_init_socket (dev_name);
    nled->dev_id = lnx_eth_get_dev_index (dev_name);

    if (nled->fd < 0) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_LINUX_ETH;
    nio->send = (void *) netio_lnxeth_send;
    nio->recv = (void *) netio_lnxeth_recv;
    nio->save_cfg = netio_lnxeth_save_cfg;
    nio->dptr = &nio->u.nled;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}
#endif /* LINUX_ETH */

/*
 * =========================================================================
 * Generic RAW Ethernet driver
 * =========================================================================
 */
#ifdef GEN_ETH
/* Free a NetIO raw ethernet descriptor */
static void netio_geneth_free (netio_geneth_desc_t * nged)
{
    gen_eth_close (nged->pcap_dev);
}

/* Write a packet to an Ethernet device */
static ssize_t netio_geneth_send (netio_geneth_desc_t * nged, void *pkt,
    size_t pkt_len)
{
    return (gen_eth_send (nged->pcap_dev, pkt, pkt_len));
}

/* Receive a packet from an Ethernet device */
static ssize_t netio_geneth_recv (netio_geneth_desc_t * nged, void *pkt,
    size_t max_len)
{
    return (gen_eth_recv (nged->pcap_dev, pkt, max_len));
}

/* Save the NIO configuration */
static void netio_geneth_save_cfg (netio_desc_t * nio, FILE * fd)
{
    netio_geneth_desc_t *nged = nio->dptr;
    fprintf (fd, "nio create_gen_eth %s %s\n", nio->name, nged->dev_name);
}

/* Create a new NetIO descriptor with generic raw Ethernet method */
netio_desc_t *netio_desc_create_geneth (char *nio_name, char *dev_name)
{
    netio_geneth_desc_t *nged;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nged = &nio->u.nged;

    if (strlen (dev_name) >= NETIO_DEV_MAXLEN) {
        fprintf (stderr,
            "netio_desc_create_geneth: bad Ethernet device string "
            "specified.\n");
        netio_free (nio, NULL);
        return NULL;
    }

    strcpy (nged->dev_name, dev_name);

    if (!(nged->pcap_dev = gen_eth_init (dev_name))) {
        netio_free (nio, NULL);
        return NULL;
    }

    nio->type = NETIO_TYPE_GEN_ETH;
    nio->send = (void *) netio_geneth_send;
    nio->recv = (void *) netio_geneth_recv;
    nio->save_cfg = netio_geneth_save_cfg;
    nio->dptr = &nio->u.nged;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}
#endif /* GEN_ETH */

/*
 * =========================================================================
 * FIFO Driver (intra-hypervisor communications)
 * =========================================================================
 */

/* Extract the first packet of the FIFO */
static netio_fifo_pkt_t *netio_fifo_extract_pkt (netio_fifo_desc_t * nfd)
{
    netio_fifo_pkt_t *p;

    if (!(p = nfd->head))
        return NULL;

    nfd->pkt_count--;
    nfd->head = p->next;

    if (!nfd->head)
        nfd->last = NULL;

    return p;
}

/* Insert a packet into the FIFO (in tail) */
static void netio_fifo_insert_pkt (netio_fifo_desc_t * nfd,
    netio_fifo_pkt_t * p)
{
    pthread_mutex_lock (&nfd->lock);

    nfd->pkt_count++;
    p->next = NULL;

    if (nfd->last) {
        nfd->last->next = p;
    } else {
        nfd->head = p;
    }

    nfd->last = p;
    pthread_mutex_unlock (&nfd->lock);
}

/* Free the packet list */
static void netio_fifo_free_pkt_list (netio_fifo_desc_t * nfd)
{
    netio_fifo_pkt_t *p, *next;

    for (p = nfd->head; p; p = next) {
        next = p->next;
        free (p);
    }

    nfd->head = nfd->last = NULL;
    nfd->pkt_count = 0;
}

/* Establish a cross-connect between two FIFO NetIO */
int netio_fifo_crossconnect (netio_desc_t * a, netio_desc_t * b)
{
    netio_fifo_desc_t *pa, *pb;

    if ((a->type != NETIO_TYPE_FIFO) || (b->type != NETIO_TYPE_FIFO))
        return (-1);

    pa = &a->u.nfd;
    pb = &b->u.nfd;

    /* A => B */
    pthread_mutex_lock (&pa->endpoint_lock);
    pthread_mutex_lock (&pa->lock);
    pa->endpoint = pb;
    netio_fifo_free_pkt_list (pa);
    pthread_mutex_unlock (&pa->lock);
    pthread_mutex_unlock (&pa->endpoint_lock);

    /* B => A */
    pthread_mutex_lock (&pb->endpoint_lock);
    pthread_mutex_lock (&pb->lock);
    pb->endpoint = pa;
    netio_fifo_free_pkt_list (pb);
    pthread_mutex_unlock (&pb->lock);
    pthread_mutex_unlock (&pb->endpoint_lock);
    return (0);
}

/* Unbind an endpoint */
static void netio_fifo_unbind_endpoint (netio_fifo_desc_t * nfd)
{
    pthread_mutex_lock (&nfd->endpoint_lock);
    nfd->endpoint = NULL;
    pthread_mutex_unlock (&nfd->endpoint_lock);
}

/* Free a NetIO FIFO descriptor */
static void netio_fifo_free (netio_fifo_desc_t * nfd)
{
    if (nfd->endpoint)
        netio_fifo_unbind_endpoint (nfd->endpoint);

    netio_fifo_free_pkt_list (nfd);
    pthread_mutex_destroy (&nfd->lock);
    pthread_cond_destroy (&nfd->cond);
}

/* Send a packet (to the endpoint FIFO) */
static ssize_t netio_fifo_send (netio_fifo_desc_t * nfd, void *pkt,
    size_t pkt_len)
{
    netio_fifo_pkt_t *p;
    size_t len;

    pthread_mutex_lock (&nfd->endpoint_lock);

    /* The cross-connect must have been established before */
    if (!nfd->endpoint)
        goto error;

    /* Allocate a a new packet and insert it into the endpoint FIFO */
    len = sizeof (netio_fifo_pkt_t) + pkt_len;
    if (!(p = malloc (len)))
        goto error;

    memcpy (p->pkt, pkt, pkt_len);
    p->pkt_len = pkt_len;
    netio_fifo_insert_pkt (nfd->endpoint, p);
    pthread_cond_signal (&nfd->endpoint->cond);
    pthread_mutex_unlock (&nfd->endpoint_lock);
    return (pkt_len);

  error:
    pthread_mutex_unlock (&nfd->endpoint_lock);
    return (-1);
}

/* Read a packet from the local FIFO queue */
static ssize_t netio_fifo_recv (netio_fifo_desc_t * nfd, void *pkt,
    size_t max_len)
{
    struct timespec ts;
    m_tmcnt_t expire;
    netio_fifo_pkt_t *p;
    size_t len = -1;

    /* Wait for the endpoint to signal a new arriving packet */
    expire = m_gettime_usec () + 50000;
    ts.tv_sec = expire / 1000000;
    ts.tv_nsec = (expire % 1000000) * 1000;

    pthread_mutex_lock (&nfd->lock);
    pthread_cond_timedwait (&nfd->cond, &nfd->lock, &ts);

    /* Extract a packet from the list */
    p = netio_fifo_extract_pkt (nfd);
    pthread_mutex_unlock (&nfd->lock);

    if (p) {
        len = m_min (p->pkt_len, max_len);
        memcpy (pkt, p->pkt, len);
        free (p);
    }

    return (len);
}

/* Create a new NetIO descriptor with FIFO method */
netio_desc_t *netio_desc_create_fifo (char *nio_name)
{
    netio_fifo_desc_t *nfd;
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nfd = &nio->u.nfd;
    pthread_mutex_init (&nfd->lock, NULL);
    pthread_mutex_init (&nfd->endpoint_lock, NULL);
    pthread_cond_init (&nfd->cond, NULL);

    nio->type = NETIO_TYPE_FIFO;
    nio->send = (void *) netio_fifo_send;
    nio->recv = (void *) netio_fifo_recv;
    nio->dptr = nfd;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}

/*
 * =========================================================================
 * NULL Driver (does nothing, used for debugging)
 * =========================================================================
 */
static ssize_t netio_null_send (void *null_ptr, void *pkt, size_t pkt_len)
{
    return (pkt_len);
}

static ssize_t netio_null_recv (void *null_ptr, void *pkt, size_t max_len)
{
    usleep (200000);
    return (-1);
}

static void netio_null_save_cfg (netio_desc_t * nio, FILE * fd)
{
    fprintf (fd, "nio create_null %s\n", nio->name);
}

/* Create a new NetIO descriptor with NULL method */
netio_desc_t *netio_desc_create_null (char *nio_name)
{
    netio_desc_t *nio;

    if (!(nio = netio_create (nio_name)))
        return NULL;

    nio->type = NETIO_TYPE_NULL;
    nio->send = (void *) netio_null_send;
    nio->recv = (void *) netio_null_recv;
    nio->save_cfg = netio_null_save_cfg;
    nio->dptr = NULL;

    if (netio_record (nio) == -1) {
        netio_free (nio, NULL);
        return NULL;
    }

    return nio;
}
#endif

/* Free a NetIO descriptor */
static int netio_free (void *data, void *arg)
{
    netio_desc_t *nio = data;

    if (nio) {

        switch (nio->type) {
        case NETIO_TYPE_TAP:
            netio_tap_free (&nio->u.ntd);
            break;
        case NETIO_TYPE_NULL:
            break;
        default:
            fprintf (stderr, "NETIO: unknown descriptor type %u\n",
                nio->type);
        }
        free (nio->name);
        free (nio);
    }

    return (TRUE);
}

#if 0
/*
 * =========================================================================
 * RX Listeners
 * =========================================================================
 */

/* Find a RX listener */
static inline struct netio_rx_listener *netio_rxl_find (netio_desc_t * nio)
{
    struct netio_rx_listener *rxl;

    for (rxl = netio_rxl_list; rxl; rxl = rxl->next)
        if (rxl->nio == nio)
            return rxl;

    return NULL;
}

/* Remove a NIO from the listener list */
static int netio_rxl_remove_internal (netio_desc_t * nio)
{
    struct netio_rx_listener *rxl;
    int res = -1;

    if ((rxl = netio_rxl_find (nio))) {
        /* we suppress this NIO only when the ref count hits 0 */
        rxl->ref_count--;

        if (!rxl->ref_count) {
            /* remove this listener from the double linked list */
            if (rxl->next)
                rxl->next->prev = rxl->prev;

            if (rxl->prev)
                rxl->prev->next = rxl->next;
            else
                netio_rxl_list = rxl->next;

            /* if this is non-FD NIO, wait for thread to terminate */
            if (netio_get_fd (rxl->nio) == -1) {
                rxl->running = FALSE;
                pthread_join (rxl->spec_thread, NULL);
            }

            free (rxl);
        }

        res = 0;
    }

    return (res);
}

/* Add a RXL listener to the listener list */
static void netio_rxl_add_internal (struct netio_rx_listener *rxl)
{
    struct netio_rx_listener *tmp;

    if ((tmp = netio_rxl_find (rxl->nio))) {
        tmp->ref_count++;
        free (rxl);
    } else {
        rxl->prev = NULL;
        rxl->next = netio_rxl_list;
        if (rxl->next)
            rxl->next->prev = rxl;
        netio_rxl_list = rxl;
    }
}

/* RX Listener dedicated thread (for non-FD NIO) */
static void *netio_rxl_spec_thread (void *arg)
{
    struct netio_rx_listener *rxl = arg;
    netio_desc_t *nio = rxl->nio;
    ssize_t pkt_len;
    while (rxl->running) {

        pkt_len = netio_recv (nio, nio->rx_pkt, sizeof (nio->rx_pkt));
        if (pkt_len > 0) {
            rxl->rx_handler (nio, nio->rx_pkt, pkt_len, rxl->arg1, rxl->arg2);
        }
    }

    return NULL;
}

/* RX Listener General Thread */
void *netio_rxl_gen_thread (void *arg)
{
    struct netio_rx_listener *rxl;
    ssize_t pkt_len;
    netio_desc_t *nio;
    struct timeval tv;
    int fd, fd_max, res;
    fd_set rfds;

    for (;;) {
        NETIO_RXL_LOCK ();

        NETIO_RXQ_LOCK ();
        /* Add the new waiting NIO to the active list */
        while (netio_rxl_add_list != NULL) {
            rxl = netio_rxl_add_list;
            netio_rxl_add_list = netio_rxl_add_list->next;
            netio_rxl_add_internal (rxl);
        }

        /* Delete the NIO present in the remove list */
        while (netio_rxl_remove_list != NULL) {
            nio = netio_rxl_remove_list;
            netio_rxl_remove_list = netio_rxl_remove_list->rxl_next;
            netio_rxl_remove_internal (nio);
        }

        pthread_cond_broadcast (&netio_rxl_cond);
        NETIO_RXQ_UNLOCK ();

        /* Build the FD set */
        FD_ZERO (&rfds);
        fd_max = -1;
        for (rxl = netio_rxl_list; rxl; rxl = rxl->next) {
            if ((fd = netio_get_fd (rxl->nio)) == -1)
                continue;

            if (fd > fd_max)
                fd_max = fd;
            FD_SET (fd, &rfds);
        }
        NETIO_RXL_UNLOCK ();

        /* Wait for incoming packets */
        tv.tv_sec = 0;
        tv.tv_usec = 2 * 1000;  /* 2 ms */
        res = select (fd_max + 1, &rfds, NULL, NULL, &tv);

        if (res == -1) {
            if (errno != EINTR)
                perror ("netio_rxl_thread: select");
            continue;
        }

        /* Examine active FDs and call user handlers */
        NETIO_RXL_LOCK ();

        for (rxl = netio_rxl_list; rxl; rxl = rxl->next) {
            nio = rxl->nio;

            if ((fd = netio_get_fd (nio)) == -1)
                continue;

            if (FD_ISSET (fd, &rfds)) {
                {
                    pkt_len =
                        netio_recv (nio, nio->rx_pkt, sizeof (nio->rx_pkt));

                    if (pkt_len > 0) {
                        rxl->rx_handler (nio, nio->rx_pkt, pkt_len, rxl->arg1,
                            rxl->arg2);
                    }
                }
            }
        }
    }
    NETIO_RXL_UNLOCK ();
}

return NULL;
}

/* Add a RX listener in the listener list */
int netio_rxl_add (netio_desc_t * nio, netio_rx_handler_t rx_handler,
    void *arg1, void *arg2)
{
    struct netio_rx_listener *rxl;

    NETIO_RXQ_LOCK ();

    if (!(rxl = malloc (sizeof (*rxl)))) {
        NETIO_RXQ_UNLOCK ();
        fprintf (stderr, "netio_rxl_add: unable to create structure.\n");
        return (-1);
    }

    memset (rxl, 0, sizeof (*rxl));
    rxl->nio = nio;
    rxl->ref_count = 1;
    rxl->rx_handler = rx_handler;
    rxl->arg1 = arg1;
    rxl->arg2 = arg2;
    rxl->running = TRUE;

    if ((netio_get_fd (rxl->nio) == -1) &&
        pthread_create (&rxl->spec_thread, NULL, netio_rxl_spec_thread, rxl)) {
        NETIO_RXQ_UNLOCK ();
        fprintf (stderr,
            "netio_rxl_add: unable to create specific thread.\n");
        free (rxl);
        return (-1);
    }

    rxl->next = netio_rxl_add_list;
    netio_rxl_add_list = rxl;

    pthread_cond_wait (&netio_rxl_cond, &netio_rxq_mutex);
    NETIO_RXQ_UNLOCK ();
    return (0);
}

/* Remove a NIO from the listener list */
int netio_rxl_remove (netio_desc_t * nio)
{
    NETIO_RXQ_LOCK ();
    nio->rxl_next = netio_rxl_remove_list;
    netio_rxl_remove_list = nio;
    pthread_cond_wait (&netio_rxl_cond, &netio_rxq_mutex);
    NETIO_RXQ_UNLOCK ();
    return (0);
}

/* Initialize the RXL thread */
int netio_rxl_init (void)
{
    pthread_cond_init (&netio_rxl_cond, NULL);

    if (pthread_create (&netio_rxl_thread, NULL, netio_rxl_gen_thread, NULL)) {
        perror ("netio_rxl_init: pthread_create");
        return (-1);
    }

    return (0);
}

#endif