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 "xio.h"
  17 #include "xutils.h"
  18 #include "built_in.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         fmemcpy(iov[iov_slot].iov_base, &phdr->raw, hdrsize);
  37         iov[iov_slot].iov_len = hdrsize;
  38
  39         fmemcpy(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, enum pcap_type type,
  47                                             uint8_t *packet, size_t len, 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         fmemcpy(&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         fmemcpy(&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 len, 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         fmemcpy(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         fmemcpy(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                 fmemcpy(&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, type, packet,
 118                                                    len, hdrsize);
 119                 if (unlikely(ret < 0))
 120                         return ret;
 121         }
 122
 123         hdrlen = pcap_get_length(phdr, type);
 124         if (unlikely(hdrlen == 0 || hdrlen > len))
 125                 return -EINVAL;
 126
 127         if (likely(iov[iov_slot].iov_len - iov_off_rd >= hdrlen)) {
 128                 fmemcpy(packet, iov[iov_slot].iov_base + iov_off_rd, hdrlen);
 129                 iov_off_rd += hdrlen;
 130         } else {
 131                 ret = __pcap_sg_inter_iov_data_read(fd, packet, len, hdrlen);
 132                 if (unlikely(ret < 0))
 133                         return ret;
 134         }
 135
 136         return hdrsize + hdrlen;
 137 }
 138
 139 static void pcap_sg_fsync(int fd)
 140 {
 141         ssize_t ret = writev(fd, iov, iov_slot);
 142         if (ret < 0)
 143                 panic("Writev I/O error: %s!\n", strerror(errno));
 144
 145         iov_slot = 0;
 146         fdatasync(fd);
 147 }
 148
 149 static int pcap_sg_prepare_access(int fd, enum pcap_mode mode, bool jumbo)
 150 {
 151         int i, ret;
 152         size_t len = 0;
 153
 154         iov_slot = 0;
 155         len = jumbo ? (PAGE_SIZE * 16) /* 64k max */ :
 156                       (PAGE_SIZE *  3) /* 12k max */;
 157
 158         for (i = 0; i < array_size(iov); ++i) {
 159                 iov[i].iov_base = xzmalloc_aligned(len, 64);
 160                 iov[i].iov_len = len;
 161         }
 162
 163         set_ioprio_rt();
 164
 165         if (mode == PCAP_MODE_RD) {
 166                 ret = readv(fd, iov, array_size(iov));
 167                 if (ret <= 0)
 168                         return -EIO;
 169
 170                 iov_off_rd = 0;
 171                 iov_slot = 0;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static void pcap_sg_prepare_close(int fd, enum pcap_mode mode)
 178 {
 179         int i;
 180
 181         for (i = 0; i < array_size(iov); ++i)
 182                 xfree(iov[i].iov_base);
 183 }
 184
 185 const struct pcap_file_ops pcap_sg_ops = {
 186         .pull_fhdr_pcap = pcap_generic_pull_fhdr,
 187         .push_fhdr_pcap = pcap_generic_push_fhdr,
 188         .prepare_access_pcap =  pcap_sg_prepare_access,
 189         .prepare_close_pcap = pcap_sg_prepare_close,
 190         .read_pcap = pcap_sg_read,
 191         .write_pcap = pcap_sg_write,
 192         .fsync_pcap = pcap_sg_fsync,
 193 };