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/*
* netsniff-ng - the packet sniffing beast
* Copyright 2011 - 2013 Daniel Borkmann.
* Subject to the GPL, version 2.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdbool.h>
#include <sys/mman.h>
#include "pcap_io.h"
#include "xio.h"
#include "xutils.h"
#include "built_in.h"
static size_t map_size = 0;
static char *ptr_va_start, *ptr_va_curr;
static void __pcap_mmap_write_need_remap(int fd)
{
int ret;
off_t pos, map_size_old = map_size;
off_t offset = ptr_va_curr - ptr_va_start;
map_size = PAGE_ALIGN(map_size_old * 10 / 8);
pos = lseek(fd, map_size, SEEK_SET);
if (pos < 0)
panic("Cannot lseek pcap file!\n");
ret = write_or_die(fd, "", 1);
if (ret != 1)
panic("Cannot write file!\n");
ptr_va_start = mremap(ptr_va_start, map_size_old, map_size, MREMAP_MAYMOVE);
if (ptr_va_start == MAP_FAILED)
panic("mmap of file failed!");
ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
if (ret < 0)
panic("Failed to give kernel mmap advise!\n");
ptr_va_curr = ptr_va_start + offset;
}
static ssize_t pcap_mm_write(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
const uint8_t *packet, size_t len)
{
size_t hdrsize = pcap_get_hdr_length(phdr, type);
if ((off_t) (ptr_va_curr - ptr_va_start) + hdrsize + len > map_size)
__pcap_mmap_write_need_remap(fd);
fmemcpy(ptr_va_curr, &phdr->raw, hdrsize);
ptr_va_curr += hdrsize;
fmemcpy(ptr_va_curr, packet, len);
ptr_va_curr += len;
return hdrsize + len;
}
static ssize_t pcap_mm_read(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
uint8_t *packet, size_t len)
{
size_t hdrsize = pcap_get_hdr_length(phdr, type), hdrlen;
if (unlikely((off_t) (ptr_va_curr + hdrsize - ptr_va_start) > map_size))
return -EIO;
fmemcpy(&phdr->raw, ptr_va_curr, hdrsize);
ptr_va_curr += hdrsize;
hdrlen = pcap_get_length(phdr, type);
if (unlikely((off_t) (ptr_va_curr + hdrlen - ptr_va_start) > map_size))
return -EIO;
if (unlikely(hdrlen == 0 || hdrlen > len))
return -EINVAL;
fmemcpy(packet, ptr_va_curr, hdrlen);
ptr_va_curr += hdrlen;
return hdrsize + hdrlen;
}
static inline off_t ____get_map_size(bool jumbo)
{
int allocsz = jumbo ? 16 : 3;
return PAGE_ALIGN(sizeof(struct pcap_filehdr) + (PAGE_SIZE * allocsz) * 1024);
}
static void __pcap_mm_prepare_access_wr(int fd, bool jumbo)
{
int ret;
off_t pos;
struct stat sb;
map_size = ____get_map_size(jumbo);
ret = fstat(fd, &sb);
if (ret < 0)
panic("Cannot fstat pcap file!\n");
if (!S_ISREG (sb.st_mode))
panic("pcap dump file is not a regular file!\n");
pos = lseek(fd, map_size, SEEK_SET);
if (pos < 0)
panic("Cannot lseek pcap file!\n");
ret = write_or_die(fd, "", 1);
if (ret != 1)
panic("Cannot write file!\n");
ptr_va_start = mmap(0, map_size, PROT_WRITE, MAP_SHARED, fd, 0);
if (ptr_va_start == MAP_FAILED)
panic("mmap of file failed!");
ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
if (ret < 0)
panic("Failed to give kernel mmap advise!\n");
ptr_va_curr = ptr_va_start + sizeof(struct pcap_filehdr);
}
static void __pcap_mm_prepare_access_rd(int fd)
{
int ret;
struct stat sb;
ret = fstat(fd, &sb);
if (ret < 0)
panic("Cannot fstat pcap file!\n");
if (!S_ISREG (sb.st_mode))
panic("pcap dump file is not a regular file!\n");
map_size = sb.st_size;
ptr_va_start = mmap(0, map_size, PROT_READ, MAP_SHARED | MAP_LOCKED, fd, 0);
if (ptr_va_start == MAP_FAILED)
panic("mmap of file failed!");
ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
if (ret < 0)
panic("Failed to give kernel mmap advise!\n");
ptr_va_curr = ptr_va_start + sizeof(struct pcap_filehdr);
}
static int pcap_mm_prepare_access(int fd, enum pcap_mode mode, bool jumbo)
{
set_ioprio_be();
switch (mode) {
case PCAP_MODE_RD:
__pcap_mm_prepare_access_rd(fd);
break;
case PCAP_MODE_WR:
__pcap_mm_prepare_access_wr(fd, jumbo);
break;
default:
bug();
}
return 0;
}
static void pcap_mm_fsync(int fd)
{
msync(ptr_va_start, (off_t) (ptr_va_curr - ptr_va_start), MS_ASYNC);
}
static void pcap_mm_prepare_close(int fd, enum pcap_mode mode)
{
int ret;
ret = munmap(ptr_va_start, map_size);
if (ret < 0)
panic("Cannot unmap the pcap file!\n");
if (mode == PCAP_MODE_WR) {
ret = ftruncate(fd, (off_t) (ptr_va_curr - ptr_va_start));
if (ret)
panic("Cannot truncate the pcap file!\n");
}
}
const struct pcap_file_ops pcap_mm_ops = {
.pull_fhdr_pcap = pcap_generic_pull_fhdr,
.push_fhdr_pcap = pcap_generic_push_fhdr,
.prepare_access_pcap = pcap_mm_prepare_access,
.prepare_close_pcap = pcap_mm_prepare_close,
.read_pcap = pcap_mm_read,
.write_pcap = pcap_mm_write,
.fsync_pcap = pcap_mm_fsync,
};
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