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 #include <string.h>
  20 #include <poll.h>
  21 #include <sys/poll.h>
  22
  23 #include "xsys.h"
  24 #include "built_in.h"
  25 #include "mtrand.h"
  26
  27 struct frame_map {
  28         struct tpacket_hdr tp_h __aligned_tpacket;
  29         struct sockaddr_ll s_ll __aligned_tpacket;
  30 };
  31
  32 struct ring {
  33         struct iovec *frames __cacheline_aligned;
  34         uint8_t *mm_space __cacheline_aligned;
  35         size_t mm_len;
  36         struct tpacket_req layout;
  37         struct sockaddr_ll s_ll;
  38 };
  39
  40 static inline void next_slot(unsigned int *it, struct ring *ring)
  41 {
  42         (*it)++;
  43         atomic_cmp_swp(it, ring->layout.tp_frame_nr, 0);
  44 }
  45
  46 static inline void next_slot_prerd(unsigned int *it, struct ring *ring)
  47 {
  48         (*it)++;
  49         atomic_cmp_swp(it, ring->layout.tp_frame_nr, 0);
  50         prefetch_rd_hi(ring->frames[*it].iov_base);
  51 }
  52
  53 static inline void next_slot_prewr(unsigned int *it, struct ring *ring)
  54 {
  55         (*it)++;
  56         atomic_cmp_swp(it, ring->layout.tp_frame_nr, 0);
  57         prefetch_wr_hi(ring->frames[*it].iov_base);
  58 }
  59
  60 static inline void next_rnd_slot(unsigned int *it, struct ring *ring)
  61 {
  62         *it = mt_rand_int32() % ring->layout.tp_frame_nr;
  63 }
  64
  65 #define RING_SIZE_FALLBACK (1 << 26)
  66
  67 static inline unsigned int ring_size(char *ifname, unsigned int size)
  68 {
  69         if (size > 0)
  70                 return size;
  71
  72         /*
  73          * Device bitrate in bytes times two as ring size.
  74          *    Fallback => ~    64,00 MB
  75          *     10 MBit => ~     2,38 MB
  76          *     54 MBit => ~    12,88 MB
  77          *    100 MBit => ~    23,84 MB
  78          *    300 MBit => ~    71,52 MB
  79          *  1.000 MBit => ~   238,42 MB
  80          * 10.000 MBit => ~ 2.384.18 MB
  81          */
  82         size = device_bitrate(ifname);
  83         size = (size * 1000000) / 8;
  84         size = size * 2;
  85         if (size == 0)
  86                 size = RING_SIZE_FALLBACK;
  87         return round_up_cacheline(size);
  88 }
  89
  90 enum ring_mode {
  91         RING_MODE_EGRESS,
  92         RING_MODE_INGRESS,
  93 };
  94
  95 static inline unsigned int ring_frame_size(struct ring *ring)
  96 {
  97         return ring->layout.tp_frame_size;
  98 }
  99
 100 static inline void tpacket_hdr_clone(struct tpacket_hdr *thdrd,
 101                                      struct tpacket_hdr *thdrs)
 102 {
 103         thdrd->tp_sec = thdrs->tp_sec;
 104         thdrd->tp_usec = thdrs->tp_usec;
 105         thdrd->tp_snaplen = thdrs->tp_snaplen;
 106         thdrd->tp_len = thdrs->tp_len;
 107 }
 108
 109 #ifndef POLLRDNORM
 110 # define POLLRDNORM     0x0040
 111 #endif
 112 #ifndef POLLWRNORM
 113 # define POLLWRNORM     0x0100
 114 #endif
 115 #ifndef POLLRDHUP
 116 # define POLLRDHUP      0x2000
 117 #endif
 118
 119 #define POLL_NEXT_PKT   0
 120 #define POLL_MOVE_OUT   1
 121
 122 static inline void prepare_polling(int sock, struct pollfd *pfd)
 123 {
 124         memset(pfd, 0, sizeof(*pfd));
 125         pfd->fd = sock;
 126         pfd->revents = 0;
 127         pfd->events = POLLIN | POLLRDNORM | POLLERR;
 128 }
 129
 130 #endif /* RING_H */