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pcap_user.c

/*
 * 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 "kern_constants.h"
#include "um_malloc.h"
#include "user.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 = 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,
};

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