pcap_sg.c

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