src/rx_ring.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   5  * Subject to the GPL.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <unistd.h>
  12 #include <sys/mman.h>
  13 #include <sys/types.h>
  14 #include <sys/socket.h>
  15 #include <arpa/inet.h>
  16 #include <linux/if_ether.h>
  17
  18 #include "xmalloc.h"
  19 #include "die.h"
  20 #include "rx_ring.h"
  21
  22 void destroy_rx_ring(int sock, struct ring *ring)
  23 {
  24         memset(&ring->layout, 0, sizeof(ring->layout));
  25         setsockopt(sock, SOL_PACKET, PACKET_RX_RING, &ring->layout,
  26                    sizeof(ring->layout));
  27
  28         munmap(ring->mm_space, ring->mm_len);
  29         ring->mm_len = 0;
  30
  31         xfree(ring->frames);
  32 }
  33
  34 void setup_rx_ring_layout(int sock, struct ring *ring, unsigned int size)
  35 {
  36         /*
  37          * FIXME: We currently have 2048 Byte per frame. Frames need to
  38          * fit exactly into blocks. Blocks can only be a multiple of the
  39          * systems page size. What do we do with jumbo frames?
  40          */
  41         memset(&ring->layout, 0, sizeof(ring->layout));
  42         ring->layout.tp_block_size = getpagesize() << 2;
  43         ring->layout.tp_frame_size = TPACKET_ALIGNMENT << 7;
  44         ring->layout.tp_block_nr = size / ring->layout.tp_block_size;
  45         ring->layout.tp_frame_nr = ring->layout.tp_block_size /
  46                                    ring->layout.tp_frame_size *
  47                                    ring->layout.tp_block_nr;
  48 }
  49
  50 void create_rx_ring(int sock, struct ring *ring)
  51 {
  52         int ret;
  53 retry:
  54         ret = setsockopt(sock, SOL_PACKET, PACKET_RX_RING, &ring->layout,
  55                          sizeof(ring->layout));
  56         if (errno == ENOMEM && ring->layout.tp_block_nr > 1) {
  57                 ring->layout.tp_block_nr >>= 1;
  58                 ring->layout.tp_frame_nr = ring->layout.tp_block_size /
  59                                            ring->layout.tp_frame_size *
  60                                            ring->layout.tp_block_nr;
  61                 goto retry;
  62         }
  63
  64         if (ret < 0)
  65                 error_and_die(EXIT_FAILURE, "Cannot allocate RX_RING!\n");
  66
  67         ring->mm_len = ring->layout.tp_block_size * ring->layout.tp_block_nr;
  68
  69         printf("RX: %.2f MB, %u Frames each %u Byte allocated\n",
  70                1.f * ring->mm_len / (1 << 20),
  71                ring->layout.tp_frame_nr, ring->layout.tp_frame_size);
  72 }
  73
  74 void mmap_rx_ring(int sock, struct ring *ring)
  75 {
  76         ring->mm_space = mmap(0, ring->mm_len, PROT_READ | PROT_WRITE,
  77                               MAP_SHARED, sock, 0);
  78         if (ring->mm_space == MAP_FAILED) {
  79                 destroy_rx_ring(sock, ring);
  80                 error_and_die(EXIT_FAILURE, "Cannot mmap RX_RING!\n");
  81         }
  82 }
  83
  84 void alloc_rx_ring_frames(struct ring *ring)
  85 {
  86         int i;
  87
  88         ring->frames = xzmalloc(ring->layout.tp_frame_nr *
  89                                 sizeof(*ring->frames));
  90
  91         for (i = 0; i < ring->layout.tp_frame_nr; ++i) {
  92                 ring->frames[i].iov_len = ring->layout.tp_frame_size;
  93                 ring->frames[i].iov_base = ring->mm_space +
  94                                            (i * ring->layout.tp_frame_size);
  95         }
  96 }
  97
  98 void bind_rx_ring(int sock, struct ring *ring, int ifindex)
  99 {
 100         /*
 101          * The RX_RING registers itself to the networking stack with
 102          * dev_add_pack(), so we have one single RX_RING for all devs
 103          * otherwise you'll get the packet twice.
 104          */
 105         memset(&ring->s_ll, 0, sizeof(ring->s_ll));
 106         ring->s_ll.sll_family = AF_PACKET;
 107         ring->s_ll.sll_protocol = htons(ETH_P_ALL);
 108         ring->s_ll.sll_ifindex = ifindex; /* Take 0 for "any"-device */
 109         ring->s_ll.sll_hatype = 0;
 110         ring->s_ll.sll_halen = 0;
 111         ring->s_ll.sll_pkttype = 0;
 112
 113         int ret = bind(sock, (struct sockaddr *) &ring->s_ll,
 114                        sizeof(ring->s_ll));
 115         if (ret < 0) {
 116                 destroy_rx_ring(sock, ring);
 117                 error_and_die(EXIT_FAILURE, "Cannot bind RX_RING!\n");
 118         }
 119 }
 120