src/capt-recvmmsg.c

   1 /* For terms of usage/redistribution/modification see the LICENSE file */
   2 /* For authors and contributors see the AUTHORS file */
   3
   4 #include "iptraf-ng-compat.h"
   5
   6 #include "packet.h"
   7 #include "capt.h"
   8
   9 #define FRAMES 128
  10
  11 struct capt_data_recvmmsg {
  12         char                    *buf;
  13
  14         struct mmsghdr          *msgvec;
  15         struct iovec            *iov;
  16         struct sockaddr_ll      *from;
  17
  18         unsigned int            lastslot;
  19         unsigned int            slot;
  20 };
  21
  22 static unsigned int capt_recvmmsg_find_filled_slot(struct capt_data_recvmmsg *data)
  23 {
  24         for (unsigned int slot = data->lastslot; slot < FRAMES; slot++)
  25                 if (data->msgvec[slot].msg_len != 0)
  26                         return slot;
  27
  28         return FRAMES;
  29 }
  30
  31 static unsigned int capt_have_packet_recvmmsg(struct capt *capt)
  32 {
  33         struct capt_data_recvmmsg *data = capt->priv;
  34
  35         return capt_recvmmsg_find_filled_slot(data) != FRAMES;
  36 }
  37
  38 static int capt_get_packet_recvmmsg(struct capt *capt, struct pkt_hdr *pkt)
  39 {
  40         struct capt_data_recvmmsg *data = capt->priv;
  41         int ret = 0;
  42
  43         unsigned int slot = capt_recvmmsg_find_filled_slot(data);
  44         if (slot == FRAMES) {
  45                 /* these are set upon return from recvmsg() so clean */
  46                 /* them beforehand */
  47                 for (unsigned int i = 0; i < FRAMES; i++) {
  48                         data->msgvec[i].msg_hdr.msg_controllen = 0;
  49                         data->msgvec[i].msg_hdr.msg_flags = 0;
  50                         data->msgvec[i].msg_len = 0;
  51                 }
  52
  53                 int received = recvmmsg(capt->fd, data->msgvec, FRAMES, MSG_TRUNC | MSG_DONTWAIT, NULL);
  54                 if (received <= 0)
  55                         return received;
  56                 slot = 0;
  57         }
  58         pkt->pkt_len = data->msgvec[slot].msg_len;
  59         pkt->pkt_caplen = data->msgvec[slot].msg_len;
  60         if (pkt->pkt_caplen > MAX_PACKET_SIZE)
  61                 pkt->pkt_caplen = MAX_PACKET_SIZE;
  62         pkt->pkt_buf = data->buf + slot * MAX_PACKET_SIZE;
  63         pkt->from = &data->from[slot];
  64         pkt->pkt_payload = NULL;
  65         pkt->pkt_protocol = ntohs(pkt->from->sll_protocol);
  66
  67         data->slot = slot;
  68
  69         return ret;
  70 }
  71
  72 static int capt_put_packet_recvmmsg(struct capt *capt, struct pkt_hdr *pkt __unused)
  73 {
  74         struct capt_data_recvmmsg *data = capt->priv;
  75
  76         /* hand out processed slot to kernel */
  77         if (data->slot < FRAMES) {
  78                 data->msgvec[data->slot].msg_len = 0;
  79                 data->lastslot = data->slot;
  80         } else
  81                 data->slot = FRAMES;
  82
  83         return 0;
  84 }
  85
  86 static void capt_cleanup_recvmmsg(struct capt *capt)
  87 {
  88         struct capt_data_recvmmsg *data = capt->priv;
  89
  90         capt->cleanup = NULL;
  91         capt->put_packet = NULL;
  92         capt->get_packet = NULL;
  93         capt->have_packet = NULL;
  94
  95         free(data->from);
  96         data->from = NULL;
  97         free(data->iov);
  98         data->iov = NULL;
  99         free(data->msgvec);
 100         data->msgvec = NULL;
 101         free(data->buf);
 102         data->buf = NULL;
 103
 104         free(capt->priv);
 105         capt->priv = NULL;
 106 }
 107
 108 int capt_setup_recvmmsg(struct capt *capt)
 109 {
 110         struct capt_data_recvmmsg *data;
 111
 112         data                    = xmallocz(sizeof(struct capt_data_recvmmsg));
 113         data->buf               = xmallocz(FRAMES * MAX_PACKET_SIZE);
 114         data->msgvec            = xmallocz(FRAMES * sizeof(*data->msgvec));
 115         data->iov               = xmallocz(FRAMES * sizeof(*data->iov));
 116         data->from              = xmallocz(FRAMES * sizeof(*data->from));
 117
 118         for (unsigned int i = 0; i < FRAMES; i++) {
 119                 data->iov[i].iov_len    = MAX_PACKET_SIZE;
 120                 data->iov[i].iov_base   = data->buf + i * MAX_PACKET_SIZE;
 121
 122                 data->msgvec[i].msg_hdr.msg_name        = &data->from[i];
 123                 data->msgvec[i].msg_hdr.msg_namelen     = sizeof(data->from[i]);
 124                 data->msgvec[i].msg_hdr.msg_iov         = &data->iov[i];
 125                 data->msgvec[i].msg_hdr.msg_iovlen      = 1;
 126                 data->msgvec[i].msg_hdr.msg_control     = NULL;
 127         }
 128         data->slot = FRAMES;
 129         data->lastslot = 0;
 130
 131         capt->priv              = data;
 132         capt->have_packet       = capt_have_packet_recvmmsg;
 133         capt->get_packet        = capt_get_packet_recvmmsg;
 134         capt->put_packet        = capt_put_packet_recvmmsg;
 135         capt->cleanup           = capt_cleanup_recvmmsg;
 136
 137         return 0;
 138 }