src/ring.h

   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, version 2.
   6  */
   7
   8 #ifndef RING_H
   9 #define RING_H
  10
  11 /*
  12  * "I love the smell of 10GbE in the morning. Smells like ... victory."
  13  *     - W. Richard Stevens, "Secret Teachings of the UNIX Environment"
  14  */
  15
  16 #include <stdio.h>
  17 #include <stdint.h>
  18 #include <linux/if_packet.h>
  19
  20 #include "xsys.h"
  21 #include "built_in.h"
  22 #include "mtrand.h"
  23
  24 #define RING_SIZE_FALLBACK (1 << 26)
  25
  26 struct frame_map {
  27         struct tpacket_hdr tp_h __aligned_tpacket;
  28         struct sockaddr_ll s_ll __aligned_tpacket;
  29 };
  30
  31 struct ring {
  32         struct iovec *frames;
  33         struct tpacket_req layout;
  34         struct sockaddr_ll s_ll;
  35         uint8_t *mm_space;
  36         size_t mm_len;
  37 } __cacheline_aligned;
  38
  39 static inline void next_slot(unsigned int *it, struct ring *ring)
  40 {
  41         *it = (*it + 1);
  42         if (*it >= ring->layout.tp_frame_nr)
  43                 *it = 0;
  44 }
  45
  46 static inline void next_rnd_slot(unsigned int *it, struct ring *ring)
  47 {
  48         *it = mt_rand_int32() % ring->layout.tp_frame_nr;
  49 }
  50
  51 static inline unsigned int ring_size(char *ifname, unsigned int size)
  52 {
  53         if (size > 0)
  54                 return size;
  55
  56         /*
  57          * Device bitrate in bytes times two as ring size.
  58          *    Fallback => ~    64,00 MB
  59          *     10 MBit => ~     2,38 MB
  60          *     54 MBit => ~    12,88 MB
  61          *    100 MBit => ~    23,84 MB
  62          *    300 MBit => ~    71,52 MB
  63          *  1.000 MBit => ~   238,42 MB
  64          * 10.000 MBit => ~ 2.384.18 MB
  65          */
  66         size = device_bitrate(ifname);
  67         size = (size * 1000000) / 8;
  68         size = size * 2;
  69         if (size == 0)
  70                 size = RING_SIZE_FALLBACK;
  71
  72         return size;
  73 }
  74
  75 enum ring_mode {
  76         RING_MODE_EGRESS,
  77         RING_MODE_INGRESS,
  78 };
  79
  80 static inline unsigned int ring_frame_size(struct ring *ring)
  81 {
  82         return ring->layout.tp_frame_size;
  83 }
  84
  85 static inline void tpacket_hdr_clone(struct tpacket_hdr *thdr_d,
  86                                      struct tpacket_hdr *thdr_s)
  87 {
  88         thdr_d->tp_sec = thdr_s->tp_sec;
  89         thdr_d->tp_usec = thdr_s->tp_usec;
  90         thdr_d->tp_snaplen = thdr_s->tp_snaplen;
  91         thdr_d->tp_len = thdr_s->tp_len;
  92 }
  93
  94 #endif /* RING_H */