umcast_user.c

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/*
 * user-mode-linux networking multicast transport
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 by Harald Welte <[email protected]>
 *
 * based on the existing uml-networking code, which is
 * Copyright (C) 2001 Lennert Buytenhek ([email protected]) and
 * James Leu ([email protected]).
 * 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 "umcast.h"
#include <net_user.h>
#include <um_malloc.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;
    if (addr)
        sin->sin_addr.s_addr = in_aton(addr);
    else
        sin->sin_addr.s_addr = INADDR_ANY;
    sin->sin_port = htons(port);
    return sin;
}

static int umcast_user_init(void *data, void *dev)
{
    struct umcast_data *pri = data;

    pri->remote_addr = new_addr(pri->addr, pri->rport);
    if (pri->unicast)
        pri->listen_addr = new_addr(NULL, pri->lport);
    else
        pri->listen_addr = pri->remote_addr;
    pri->dev = dev;
    return 0;
}

static void umcast_remove(void *data)
{
    struct umcast_data *pri = data;

    kfree(pri->listen_addr);
    if (pri->unicast)
        kfree(pri->remote_addr);
    pri->listen_addr = pri->remote_addr = NULL;
}

static int umcast_open(void *data)
{
    struct umcast_data *pri = data;
    struct sockaddr_in *lsin = pri->listen_addr;
    struct sockaddr_in *rsin = pri->remote_addr;
    struct ip_mreq mreq;
    int fd, yes = 1, err = -EINVAL;


    if ((!pri->unicast && lsin->sin_addr.s_addr == 0) ||
        (rsin->sin_addr.s_addr == 0) ||
        (lsin->sin_port == 0) || (rsin->sin_port == 0))
        goto out;

    fd = socket(AF_INET, SOCK_DGRAM, 0);

    if (fd < 0) {
        err = -errno;
        printk(UM_KERN_ERR "umcast_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 "umcast_open: SO_REUSEADDR failed, "
               "errno = %d\n", errno);
        goto out_close;
    }

    if (!pri->unicast) {
        /* 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 "umcast_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 "umcast_open: IP_MULTICAST_LOOP "
                   "failed, error = %d\n", errno);
            goto out_close;
        }
    }

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

    if (!pri->unicast) {
        /* subscribe to the multicast group */
        mreq.imr_multiaddr.s_addr = lsin->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 "umcast_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 umcast_close(int fd, void *data)
{
    struct umcast_data *pri = data;

    if (!pri->unicast) {
        struct ip_mreq mreq;
        struct sockaddr_in *lsin = pri->listen_addr;

        mreq.imr_multiaddr.s_addr = lsin->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 "umcast_close: IP_DROP_MEMBERSHIP "
                   "failed, error = %d\n", errno);
        }
    }

    close(fd);
}

int umcast_user_write(int fd, void *buf, int len, struct umcast_data *pri)
{
    struct sockaddr_in *data_addr = pri->remote_addr;

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

const struct net_user_info umcast_user_info = {
    .init   = umcast_user_init,
    .open   = umcast_open,
    .close  = umcast_close,
    .remove = umcast_remove,
    .add_address    = NULL,
    .delete_address = NULL,
    .mtu    = ETH_MAX_PACKET,
    .max_packet = ETH_MAX_PACKET + ETH_HEADER_OTHER,
};