src/common/cache.c
/* $Id$ */
/*
* Copyright (c) 2001-2010 Aaron Turner <aturner at synfin dot net>
* Copyright (c) 2013-2022 Fred Klassen <tcpreplay at appneta dot com> - AppNeta
*
* The Tcpreplay Suite of tools is free software: you can redistribute it
* and/or modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or with the authors permission any later version.
*
* The Tcpreplay Suite is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with the Tcpreplay Suite. If not, see <http://www.gnu.org/licenses/>.
*/
#include "defines.h"
#include "config.h"
#include "common.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
static tcpr_cache_t *new_cache(void);
/**
* Takes a single char and returns a ptr to a string representation of the
* 8 bits that make up that char. Use BIT_STR() to print it out
*/
#ifdef DEBUG
static char *
byte2bits(char byte, char *bitstring)
{
int i, j = 7;
for (i = 1; i <= 255; i = i << 1) {
if (byte & i)
bitstring[j] = '\061';
j--;
}
return bitstring;
}
#endif
/**
* simple function to read in a cache file created with tcpprep this let's us
* be really damn fast in picking an interface to send the packet out returns
* number of cache entries read
*
* now also checks for the cache magic and version
*/
COUNTER
read_cache(char **cachedata, const char *cachefile, char **comment)
{
int cachefd;
tcpr_cache_file_hdr_t header;
ssize_t read_size;
COUNTER cache_size;
assert(cachedata);
assert(comment);
/* open the file or abort */
if ((cachefd = open(cachefile, O_RDONLY)) == -1)
errx(-1, "unable to open %s:%s", cachefile, strerror(errno));
/* read the cache header and determine compatibility */
if ((read_size = read(cachefd, &header, sizeof(header))) < 0)
errx(-1, "unable to read from %s:%s,", cachefile, strerror(errno));
if (read_size < (ssize_t)sizeof(header))
errx(-1, "Cache file %s doesn't contain a full header", cachefile);
/* verify our magic: tcpprep\0 */
if (memcmp(header.magic, CACHEMAGIC, sizeof(CACHEMAGIC)) != 0)
errx(-1, "Unable to process %s: not a tcpprep cache file", cachefile);
/* verify version */
if (strtol(header.version, NULL, 10) != strtol(CACHEVERSION, NULL, 10))
errx(-1, "Unable to process %s: cache file version mismatch", cachefile);
/* read the comment */
header.comment_len = ntohs(header.comment_len);
if (header.comment_len > 65534)
errx(-1, "Unable to process %s: invalid comment length %u", cachefile, header.comment_len);
*comment = (char *)safe_malloc(header.comment_len + 1);
dbgx(1, "Comment length: %d", header.comment_len);
if ((read_size = read(cachefd, *comment, header.comment_len)) < 0)
errx(-1, "Error reading comment: %s", strerror(errno));
if (read_size != (ssize_t)header.comment_len)
errx(-1, "Invalid comment read: expected=%u actual=%zd bytes", header.comment_len, read_size);
dbgx(1, "Cache file comment: %s", *comment);
/* malloc our cache block */
header.num_packets = ntohll(header.num_packets);
header.packets_per_byte = ntohs(header.packets_per_byte);
cache_size = header.num_packets / header.packets_per_byte;
/* deal with any remainder, because above division is integer */
if (header.num_packets % header.packets_per_byte)
cache_size++;
dbgx(1, "Cache file contains %" PRIu64 " packets in " COUNTER_SPEC " bytes", header.num_packets, cache_size);
dbgx(1, "Cache uses %d packets per byte", header.packets_per_byte);
*cachedata = (char *)safe_malloc(cache_size);
/* read in the cache */
if ((COUNTER)(read_size = read(cachefd, *cachedata, cache_size)) != cache_size)
errx(-1,
"Cache data length (%zu bytes) doesn't match "
"cache header (" COUNTER_SPEC " bytes)",
read_size,
cache_size);
dbgx(1, "Loaded in %" PRIu64 " packets from cache.", header.num_packets);
close(cachefd);
return (header.num_packets);
}
/**
* writes out the cache file header, comment and then the
* contents of *cachedata to out_file and then returns the number
* of cache entries written
*/
COUNTER
write_cache(tcpr_cache_t *cachedata, const int out_file, COUNTER numpackets, char *comment)
{
tcpr_cache_t *mycache = NULL;
tcpr_cache_file_hdr_t *cache_header = NULL;
uint32_t chars, last = 0;
COUNTER packets = 0;
ssize_t written;
assert(out_file);
/* write a header to our file */
cache_header = (tcpr_cache_file_hdr_t *)safe_malloc(sizeof(tcpr_cache_file_hdr_t));
strncpy(cache_header->magic, CACHEMAGIC, strlen(CACHEMAGIC) + 1);
strncpy(cache_header->version, CACHEVERSION, strlen(CACHEVERSION) + 1);
cache_header->packets_per_byte = htons(CACHE_PACKETS_PER_BYTE);
cache_header->num_packets = htonll((u_int64_t)numpackets);
/* we can't strlen(NULL) so ... */
if (comment != NULL) {
cache_header->comment_len = htons((uint16_t)strlen(comment));
} else {
cache_header->comment_len = 0;
}
written = write(out_file, cache_header, sizeof(tcpr_cache_file_hdr_t));
dbgx(1, "Wrote %zu bytes of cache file header", written);
if (written != sizeof(tcpr_cache_file_hdr_t))
errx(-1,
"Only wrote %zu of %zu bytes of the cache file header!\n%s",
written,
sizeof(tcpr_cache_file_hdr_t),
written == -1 ? strerror(errno) : "");
/* don't write comment if there is none */
if (comment != NULL) {
written = write(out_file, comment, strlen(comment));
dbgx(1, "Wrote %zu bytes of comment", written);
if (written != (ssize_t)strlen(comment))
errx(-1,
"Only wrote %zu of %zu bytes of the comment!\n%s",
written,
strlen(comment),
written == -1 ? strerror(errno) : "");
}
if (cachedata) {
mycache = cachedata;
while (!last) {
/* increment total packets */
packets += mycache->packets;
/* calculate how many chars to write */
chars = mycache->packets / CACHE_PACKETS_PER_BYTE;
if (mycache->packets % CACHE_PACKETS_PER_BYTE) {
chars++;
dbgx(1, "Bumping up to the next byte: %d %% %d", mycache->packets, CACHE_PACKETS_PER_BYTE);
}
/* write to file, and verify it wrote properly */
written = write(out_file, mycache->data, chars);
dbgx(1, "Wrote %zu bytes of cache data", written);
if (written != (ssize_t)chars)
errx(-1, "Only wrote %zu of %i bytes to cache file!", written, chars);
/*
* if that was the last, stop processing, otherwise wash,
* rinse, repeat
*/
if (mycache->next != NULL) {
mycache = mycache->next;
} else {
last = 1;
}
}
}
safe_free(cache_header);
/* return number of packets written */
return (packets);
}
/**
* mallocs a new CACHE struct all pre-set to sane defaults
*/
static tcpr_cache_t *
new_cache(void)
{
tcpr_cache_t *newcache;
/* malloc mem */
newcache = (tcpr_cache_t *)safe_malloc(sizeof(tcpr_cache_t));
return (newcache);
}
/**
* adds the cache data for a packet to the given cachedata
*/
tcpr_dir_t
add_cache(tcpr_cache_t **cachedata, const int send, const tcpr_dir_t interface)
{
static tcpr_cache_t *lastcache = NULL;
tcpr_dir_t result;
#ifdef DEBUG
char bitstring[9] = EIGHT_ZEROS;
#endif
assert(cachedata);
/* first run? malloc our first entry, set bit count to 0 */
if (*cachedata == NULL || lastcache == NULL) {
*cachedata = new_cache();
lastcache = *cachedata;
} else {
/* check to see if this is the last bit in this struct */
if ((lastcache->packets + 1) > (CACHEDATASIZE * CACHE_PACKETS_PER_BYTE)) {
/*
* if so, we have to malloc a new one and set bit to 0
*/
dbg(1, "Adding to cachedata linked list");
lastcache->next = new_cache();
lastcache = lastcache->next;
}
}
/* always increment our bit count */
lastcache->packets++;
dbgx(1, "Cache array packet %d", lastcache->packets);
/* send packet ? */
if (send == SEND) {
COUNTER index;
uint32_t bit;
u_char *byte;
index = (lastcache->packets - 1) / (COUNTER)CACHE_PACKETS_PER_BYTE;
bit = (((lastcache->packets - 1) % (COUNTER)CACHE_PACKETS_PER_BYTE) * (COUNTER)CACHE_BITS_PER_PACKET) + 1;
dbgx(3, "Bit: %d", bit);
byte = (u_char *)&lastcache->data[index];
*byte += (u_char)(1 << bit);
dbgx(2, "set send bit: byte " COUNTER_SPEC " = 0x%x", index, *byte);
/* if true, set low order bit. else, do squat */
if (interface == TCPR_DIR_C2S) {
*byte += (u_char)(1 << (bit - 1));
dbgx(2, "set interface bit: byte " COUNTER_SPEC " = 0x%x", index, *byte);
result = TCPR_DIR_C2S;
} else {
dbgx(2, "don't set interface bit: byte " COUNTER_SPEC " = 0x%x", index, *byte);
result = TCPR_DIR_S2C;
}
#ifdef DEBUG
/*
* only build the byte string when not in debug mode since
* the calculation is a bit expensive
*/
dbgx(3, "Current cache byte: %c%c%c%c%c%c%c%c", BIT_STR(byte2bits(*byte, bitstring)));
#endif
} else {
dbg(1, "not setting send bit");
result = TCPR_DIR_NOSEND;
}
return result;
}
/**
* returns the action for a given packet based on the CACHE
*/
tcpr_dir_t
check_cache(char *cachedata, COUNTER packetid)
{
COUNTER index;
uint32_t bit;
assert(cachedata);
if (packetid == 0)
err(-1, "packetid must be > 0");
index = (packetid - 1) / (COUNTER)CACHE_PACKETS_PER_BYTE;
bit = (uint32_t)(((packetid - 1) % (COUNTER)CACHE_PACKETS_PER_BYTE) * (COUNTER)CACHE_BITS_PER_PACKET) + 1;
#ifdef DEBUG
dbgx(3,
"Index: " COUNTER_SPEC "\tBit: %d\tByte: %hhu\tMask: %hhu",
index,
bit,
cachedata[index],
(uint8_t)(cachedata[index] & (char)(1 << bit)));
#endif
if (!(cachedata[index] & (char)(1 << bit))) {
return TCPR_DIR_NOSEND;
}
/* go back a bit to get the interface */
bit--;
if (cachedata[index] & (char)(1 << bit)) {
return TCPR_DIR_C2S;
} else {
return TCPR_DIR_S2C;
}
}