libdabba/packet_rx.c

   1 /**
   2  * \file packet_rx.c
   3  * \author written by Emmanuel Roullit emmanuel.roullit@gmail.com (c) 2011
   4  * \date 2011
   5  */
   6
   7 /* __LICENSE_HEADER_BEGIN__ */
   8
   9 /*
  10  * Copyright (C) 2011   Emmanuel Roullit <emmanuel.roullit@gmail.com>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or (at
  15  * your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along
  23  * with this program; if not, write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
  25  *
  26  */
  27
  28  /* __LICENSE_HEADER_END__ */
  29
  30 #define _GNU_SOURCE
  31
  32 #include <assert.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35 #include <sys/uio.h>
  36 #include <poll.h>
  37
  38 #include <libdabba/packet_rx.h>
  39 #include <libdabba/pcap.h>
  40 #include <libdabba/macros.h>
  41
  42 /**
  43  * \brief Receive packets coming from a packet mmap RX ring
  44  * \param[in] arg       Pointer to packet rx thread structure
  45  * \return Always return NULL
  46  *
  47  * This function will \c poll(2) until some packets are received on the configured
  48  * interface. For now this function does not much but it can be starting point
  49  * for PCAP function to dump the frames into a file or for a packet dissectors.
  50  */
  51
  52 void *packet_rx(void *arg)
  53 {
  54         struct packet_rx_thread *thread = arg;
  55         struct packet_mmap *pkt_rx = &thread->pkt_rx;
  56         struct pollfd pfd;
  57         size_t index = 0;
  58
  59         if (!arg)
  60                 goto out;
  61
  62         pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
  63
  64         memset(&pfd, 0, sizeof(pfd));
  65
  66         pfd.events = POLLIN | POLLRDNORM | POLLERR;
  67         pfd.fd = pkt_rx->pf_sock;
  68
  69         for (;;) {
  70                 for (index = 0; index < pkt_rx->layout.tp_frame_nr; index++) {
  71                         struct packet_mmap_header *mmap_hdr =
  72                             pkt_rx->vec[index].iov_base;
  73
  74                         if ((mmap_hdr->tp_h.tp_status & TP_STATUS_KERNEL) ==
  75                             TP_STATUS_KERNEL) {
  76                                 if (poll(&pfd, 1, -1) < 0)
  77                                         continue;
  78                         }
  79
  80                         if ((mmap_hdr->tp_h.tp_status & TP_STATUS_USER) ==
  81                             TP_STATUS_USER) {
  82                                 if (thread->pcap_fd > 0) {
  83                                         pcap_write(thread->pcap_fd,
  84                                                    (uint8_t *) mmap_hdr +
  85                                                    mmap_hdr->tp_h.tp_mac,
  86                                                    mmap_hdr->tp_h.tp_len,
  87                                                    min(mmap_hdr->tp_h.tp_snaplen, pkt_rx->layout.tp_frame_size),
  88                                                    mmap_hdr->tp_h.tp_sec,
  89                                                    mmap_hdr->tp_h.tp_usec);
  90                                 }
  91
  92                                 mmap_hdr->tp_h.tp_status = TP_STATUS_KERNEL;
  93                         }
  94                 }
  95         }
  96
  97  out:
  98         pthread_exit(NULL);
  99 }