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mcast_user.c

/*
 * user-mode-linux networking multicast transport
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
 *
 * based on the existing uml-networking code, which is
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
 * James Leu (jleu@mindspring.net).
 * Copyright (C) 2001 by various other people who didn't put their name here.
 *
 * Licensed under the GPL.
 *
 */

#include <unistd.h>
#include <errno.h>
#include <netinet/in.h>
#include "kern_constants.h"
#include "mcast.h"
#include "net_user.h"
#include "um_malloc.h"
#include "user.h"

static struct sockaddr_in *new_addr(char *addr, unsigned short port)
{
      struct sockaddr_in *sin;

      sin = uml_kmalloc(sizeof(struct sockaddr_in), UM_GFP_KERNEL);
      if (sin == NULL) {
            printk(UM_KERN_ERR "new_addr: allocation of sockaddr_in "
                   "failed\n");
            return NULL;
      }
      sin->sin_family = AF_INET;
      sin->sin_addr.s_addr = in_aton(addr);
      sin->sin_port = htons(port);
      return sin;
}

static int mcast_user_init(void *data, void *dev)
{
      struct mcast_data *pri = data;

      pri->mcast_addr = new_addr(pri->addr, pri->port);
      pri->dev = dev;
      return 0;
}

static void mcast_remove(void *data)
{
      struct mcast_data *pri = data;

      kfree(pri->mcast_addr);
      pri->mcast_addr = NULL;
}

static int mcast_open(void *data)
{
      struct mcast_data *pri = data;
      struct sockaddr_in *sin = pri->mcast_addr;
      struct ip_mreq mreq;
      int fd, yes = 1, err = -EINVAL;


      if ((sin->sin_addr.s_addr == 0) || (sin->sin_port == 0))
            goto out;

      fd = socket(AF_INET, SOCK_DGRAM, 0);

      if (fd < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open : data socket failed, "
                   "errno = %d\n", errno);
            goto out;
      }

      if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open: SO_REUSEADDR failed, "
                   "errno = %d\n", errno);
            goto out_close;
      }

      /* set ttl according to config */
      if (setsockopt(fd, SOL_IP, IP_MULTICAST_TTL, &pri->ttl,
                   sizeof(pri->ttl)) < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_TTL failed, "
                   "error = %d\n", errno);
            goto out_close;
      }

      /* set LOOP, so data does get fed back to local sockets */
      if (setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP, &yes, sizeof(yes)) < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_LOOP failed, "
                   "error = %d\n", errno);
            goto out_close;
      }

      /* bind socket to mcast address */
      if (bind(fd, (struct sockaddr *) sin, sizeof(*sin)) < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open : data bind failed, "
                   "errno = %d\n", errno);
            goto out_close;
      }

      /* subscribe to the multicast group */
      mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
      mreq.imr_interface.s_addr = 0;
      if (setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP,
                   &mreq, sizeof(mreq)) < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mcast_open: IP_ADD_MEMBERSHIP failed, "
                   "error = %d\n", errno);
            printk(UM_KERN_ERR "There appears not to be a multicast-"
                   "capable network interface on the host.\n");
            printk(UM_KERN_ERR "eth0 should be configured in order to use "
                   "the multicast transport.\n");
            goto out_close;
      }

      return fd;

 out_close:
      close(fd);
 out:
      return err;
}

static void mcast_close(int fd, void *data)
{
      struct ip_mreq mreq;
      struct mcast_data *pri = data;
      struct sockaddr_in *sin = pri->mcast_addr;

      mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
      mreq.imr_interface.s_addr = 0;
      if (setsockopt(fd, SOL_IP, IP_DROP_MEMBERSHIP,
                   &mreq, sizeof(mreq)) < 0) {
            printk(UM_KERN_ERR "mcast_open: IP_DROP_MEMBERSHIP failed, "
                   "error = %d\n", errno);
      }

      close(fd);
}

int mcast_user_write(int fd, void *buf, int len, struct mcast_data *pri)
{
      struct sockaddr_in *data_addr = pri->mcast_addr;

      return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
}

const struct net_user_info mcast_user_info = {
      .init       = mcast_user_init,
      .open       = mcast_open,
      .close            = mcast_close,
      .remove           = mcast_remove,
      .add_address      = NULL,
      .delete_address = NULL,
      .mtu        = ETH_MAX_PACKET,
      .max_packet = ETH_MAX_PACKET + ETH_HEADER_OTHER,
};

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