pcap_user.c

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/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL.
 */

#include <errno.h>
#include <pcap.h>
#include <string.h>
#include <asm/types.h>
#include <net_user.h>
#include "pcap_user.h"
#include <um_malloc.h>

#define PCAP_FD(p) (*(int *)(p))

static int pcap_user_init(void *data, void *dev)
{
    struct pcap_data *pri = data;
    pcap_t *p;
    char errors[PCAP_ERRBUF_SIZE];

    p = pcap_open_live(pri->host_if, ETH_MAX_PACKET + ETH_HEADER_OTHER,
               pri->promisc, 0, errors);
    if (p == NULL) {
        printk(UM_KERN_ERR "pcap_user_init : pcap_open_live failed - "
               "'%s'\n", errors);
        return -EINVAL;
    }

    pri->dev = dev;
    pri->pcap = p;
    return 0;
}

static int pcap_open(void *data)
{
    struct pcap_data *pri = data;
    __u32 netmask;
    int err;

    if (pri->pcap == NULL)
        return -ENODEV;

    if (pri->filter != NULL) {
        err = dev_netmask(pri->dev, &netmask);
        if (err < 0) {
            printk(UM_KERN_ERR "pcap_open : dev_netmask failed\n");
            return -EIO;
        }

        pri->compiled = uml_kmalloc(sizeof(struct bpf_program),
                    UM_GFP_KERNEL);
        if (pri->compiled == NULL) {
            printk(UM_KERN_ERR "pcap_open : kmalloc failed\n");
            return -ENOMEM;
        }

        err = pcap_compile(pri->pcap,
                   (struct bpf_program *) pri->compiled,
                   pri->filter, pri->optimize, netmask);
        if (err < 0) {
            printk(UM_KERN_ERR "pcap_open : pcap_compile failed - "
                   "'%s'\n", pcap_geterr(pri->pcap));
            goto out;
        }

        err = pcap_setfilter(pri->pcap, pri->compiled);
        if (err < 0) {
            printk(UM_KERN_ERR "pcap_open : pcap_setfilter "
                   "failed - '%s'\n", pcap_geterr(pri->pcap));
            goto out;
        }
    }

    return PCAP_FD(pri->pcap);

 out:
    kfree(pri->compiled);
    return -EIO;
}

static void pcap_remove(void *data)
{
    struct pcap_data *pri = data;

    if (pri->compiled != NULL)
        pcap_freecode(pri->compiled);

    if (pri->pcap != NULL)
        pcap_close(pri->pcap);
}

struct pcap_handler_data {
    char *buffer;
    int len;
};

static void handler(u_char *data, const struct pcap_pkthdr *header,
            const u_char *packet)
{
    int len;

    struct pcap_handler_data *hdata = (struct pcap_handler_data *) data;

    len = hdata->len < header->caplen ? hdata->len : header->caplen;
    memcpy(hdata->buffer, packet, len);
    hdata->len = len;
}

int pcap_user_read(int fd, void *buffer, int len, struct pcap_data *pri)
{
    struct pcap_handler_data hdata = ((struct pcap_handler_data)
                                  { .buffer     = buffer,
                        .len    = len });
    int n;

    n = pcap_dispatch(pri->pcap, 1, handler, (u_char *) &hdata);
    if (n < 0) {
        printk(UM_KERN_ERR "pcap_dispatch failed - %s\n",
               pcap_geterr(pri->pcap));
        return -EIO;
    }
    else if (n == 0)
        return 0;
    return hdata.len;
}

const struct net_user_info pcap_user_info = {
    .init       = pcap_user_init,
    .open       = pcap_open,
    .close      = NULL,
    .remove     = pcap_remove,
    .add_address    = NULL,
    .delete_address = NULL,
    .mtu        = ETH_MAX_PACKET,
    .max_packet = ETH_MAX_PACKET + ETH_HEADER_OTHER,
};