pcap_sg.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2011 - 2013 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #include <stdio.h>
   8 #include <sys/types.h>
   9 #include <sys/stat.h>
  10 #include <fcntl.h>
  11 #include <sys/uio.h>
  12 #include <unistd.h>
  13
  14 #include "pcap_io.h"
  15 #include "xmalloc.h"
  16 #include "built_in.h"
  17 #include "iosched.h"
  18 #include "ioops.h"
  19
  20 static struct iovec iov[1024] __cacheline_aligned;
  21 static off_t iov_off_rd = 0, iov_slot = 0;
  22
  23 static ssize_t pcap_sg_write(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
  24                              const uint8_t *packet, size_t len)
  25 {
  26         ssize_t ret, hdrsize = pcap_get_hdr_length(phdr, type);
  27
  28         if (unlikely(iov_slot == array_size(iov))) {
  29                 ret = writev(fd, iov, array_size(iov));
  30                 if (ret < 0)
  31                         panic("Writev I/O error: %s!\n", strerror(errno));
  32
  33                 iov_slot = 0;
  34         }
  35
  36         memcpy(iov[iov_slot].iov_base, &phdr->raw, hdrsize);
  37         iov[iov_slot].iov_len = hdrsize;
  38
  39         memcpy(iov[iov_slot].iov_base + iov[iov_slot].iov_len, packet, len);
  40         ret = (iov[iov_slot].iov_len += len);
  41
  42         iov_slot++;
  43         return ret;
  44 }
  45
  46 static ssize_t __pcap_sg_inter_iov_hdr_read(int fd, pcap_pkthdr_t *phdr,
  47                                             size_t hdrsize)
  48 {
  49         int ret;
  50         size_t offset = 0;
  51         ssize_t remainder;
  52
  53         offset = iov[iov_slot].iov_len - iov_off_rd;
  54         remainder = hdrsize - offset;
  55         if (remainder < 0)
  56                 remainder = 0;
  57
  58         bug_on(offset + remainder != hdrsize);
  59
  60         memcpy(&phdr->raw, iov[iov_slot].iov_base + iov_off_rd, offset);
  61         iov_off_rd = 0;
  62         iov_slot++;
  63
  64         if (iov_slot == array_size(iov)) {
  65                 iov_slot = 0;
  66                 ret = readv(fd, iov, array_size(iov));
  67                 if (unlikely(ret <= 0))
  68                         return -EIO;
  69         }
  70
  71         memcpy(&phdr->raw + offset, iov[iov_slot].iov_base + iov_off_rd, remainder);
  72         iov_off_rd += remainder;
  73
  74         return hdrsize;
  75 }
  76
  77 static ssize_t __pcap_sg_inter_iov_data_read(int fd, uint8_t *packet, size_t hdrlen)
  78 {
  79         int ret;
  80         size_t offset = 0;
  81         ssize_t remainder;
  82
  83         offset = iov[iov_slot].iov_len - iov_off_rd;
  84         remainder = hdrlen - offset;
  85         if (remainder < 0)
  86                 remainder = 0;
  87
  88         bug_on(offset + remainder != hdrlen);
  89
  90         memcpy(packet, iov[iov_slot].iov_base + iov_off_rd, offset);
  91         iov_off_rd = 0;
  92         iov_slot++;
  93
  94         if (iov_slot == array_size(iov)) {
  95                 iov_slot = 0;
  96                 ret = readv(fd, iov, array_size(iov));
  97                 if (unlikely(ret <= 0))
  98                         return -EIO;
  99         }
 100
 101         memcpy(packet + offset, iov[iov_slot].iov_base + iov_off_rd, remainder);
 102         iov_off_rd += remainder;
 103
 104         return hdrlen;
 105 }
 106
 107 static ssize_t pcap_sg_read(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
 108                             uint8_t *packet, size_t len)
 109 {
 110         ssize_t ret = 0;
 111         size_t hdrsize = pcap_get_hdr_length(phdr, type), hdrlen;
 112
 113         if (likely(iov[iov_slot].iov_len - iov_off_rd >= hdrsize)) {
 114                 memcpy(&phdr->raw, iov[iov_slot].iov_base + iov_off_rd, hdrsize);
 115                 iov_off_rd += hdrsize;
 116         } else {
 117                 ret = __pcap_sg_inter_iov_hdr_read(fd, phdr, hdrsize);
 118                 if (unlikely(ret < 0))
 119                         return ret;
 120         }
 121
 122         hdrlen = pcap_get_length(phdr, type);
 123         if (unlikely(hdrlen == 0 || hdrlen > len))
 124                 return -EINVAL;
 125
 126         if (likely(iov[iov_slot].iov_len - iov_off_rd >= hdrlen)) {
 127                 memcpy(packet, iov[iov_slot].iov_base + iov_off_rd, hdrlen);
 128                 iov_off_rd += hdrlen;
 129         } else {
 130                 ret = __pcap_sg_inter_iov_data_read(fd, packet, hdrlen);
 131                 if (unlikely(ret < 0))
 132                         return ret;
 133         }
 134
 135         return hdrsize + hdrlen;
 136 }
 137
 138 static void pcap_sg_fsync(int fd)
 139 {
 140         ssize_t ret = writev(fd, iov, iov_slot);
 141         if (ret < 0)
 142                 panic("Writev I/O error: %s!\n", strerror(errno));
 143
 144         iov_slot = 0;
 145         fdatasync(fd);
 146 }
 147
 148 static void pcap_sg_init_once(bool enforce_prio)
 149 {
 150         if (enforce_prio)
 151                 set_ioprio_rt();
 152 }
 153
 154 static int pcap_sg_prepare_access(int fd, enum pcap_mode mode, bool jumbo)
 155 {
 156         int ret;
 157         size_t i, len = 0;
 158
 159         iov_slot = 0;
 160         len = jumbo ? (RUNTIME_PAGE_SIZE * 16) /* 64k max */ :
 161                       (RUNTIME_PAGE_SIZE *  3) /* 12k max */;
 162
 163         for (i = 0; i < array_size(iov); ++i) {
 164                 iov[i].iov_base = xzmalloc_aligned(len, 64);
 165                 iov[i].iov_len = len;
 166         }
 167
 168         if (mode == PCAP_MODE_RD) {
 169                 ret = readv(fd, iov, array_size(iov));
 170                 if (ret <= 0)
 171                         return -EIO;
 172
 173                 iov_off_rd = 0;
 174                 iov_slot = 0;
 175         }
 176
 177         return 0;
 178 }
 179
 180 static void pcap_sg_prepare_close(int fd __maybe_unused,
 181                                   enum pcap_mode mode __maybe_unused)
 182 {
 183         size_t i;
 184
 185         for (i = 0; i < array_size(iov); ++i)
 186                 xfree(iov[i].iov_base);
 187 }
 188
 189 const struct pcap_file_ops pcap_sg_ops = {
 190         .init_once_pcap = pcap_sg_init_once,
 191         .pull_fhdr_pcap = pcap_generic_pull_fhdr,
 192         .push_fhdr_pcap = pcap_generic_push_fhdr,
 193         .prepare_access_pcap =  pcap_sg_prepare_access,
 194         .prepare_close_pcap = pcap_sg_prepare_close,
 195         .read_pcap = pcap_sg_read,
 196         .write_pcap = pcap_sg_write,
 197         .fsync_pcap = pcap_sg_fsync,
 198 };