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wireshark/mkcap.c

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/* mkcap.c
* A small program to generate the ASCII form of a capture with TCP
* segments of a reasonable nature. The payload is all zeros.
*
* $Id$
*
* By Ronnie Sahlberg and Richard Sharpe. From a program initially
* written by Ronnie.
* Copyright 2003 Ronnie Sahlberg and Richard Sharpe
*
* This program 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 2
* of the License, or (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Using it to generate a capture file:
* ./mkcap [some-flags] > some-file
* text2pcap [some-other-flags] some-file some-file.cap
* For example:
./mkcap -a 2500 -s 15 -I "02 03 04 05" -i "45 45 45 45" -P "00 14" > ftp.cap.asci
text2pcap -t "%Y/%m/%d%t%H:%M:%S." ftp.cap.asci ftp.cap
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define ETH_1 "00 00 9c fa 1d 74"
#define ETH_2 "00 1a b8 93 f6 71"
#define IP_1 "0a 01 01 17"
#define IP_2 "0a 01 01 ea"
#define PORT_1 "01 00"
#define PORT_2 "10 00"
char *eth_1 = ETH_1;
char *eth_2 = ETH_2;
char *ip_1 = IP_1;
char *ip_2 = IP_2;
char *port_1 = PORT_1;
char *port_2 = PORT_2;
int verbose = 0;
typedef enum {
normal = 0,
random_ack_drop = 1,
random_data_drop = 2,
} run_type_t;
typedef struct {
int drop_seg_start;
int drop_seg_count;
} seg_drop_t;
/*
* The array of which segments should be dropped ...
*/
seg_drop_t *drops = NULL;
int seg_drop_count = 0;
/* The array of which ACKs should be dropped. This is complicated because
* An ack might not be generated for a segment because of delayed ACKs.
*/
seg_drop_t *ack_drops = NULL;
int ack_drop_count = 0;
int total_bytes = 32768;
int run_type = 0;
int seq_2=0;
int seq_1=0;
int ts=0;
int jitter = 0;
int send_spacing = 10;
int ack_delay = 5000;
int tcp_nodelay = 0;
int tcp_delay_time = 1000; /* What is the real time here? */
/*
* If tcp_nodelay is set, then this is the amount of data left ...
*/
int remaining_data = 0;
int snap_len = 1500;
int window = 32768;
int ssthresh = 16384;
int cwnd = 1460;
int used_win = 0;
int segment = 0;
#define SEG_ACK_LOST 1
#define SEG_SEG_LOST 2
struct seg_hist_s {
int seq_num; /* First sequence number in segment */
int len; /* Number of bytes in segment */
int ts; /* Timestamp when sent */
int seg_num; /* Segment number sent. This can change */
/* but a retransmit will have a new seg */
int flags; /* Flags as above for ack and seg loss */
int acks_first_seq; /* How many times we have seen an ack
for the first seq number in this seg */
};
#define SEG_HIST_SIZE 128
struct seg_hist_s seg_hist[128]; /* This should be dynamic */
int next_slot = 0;
int first_slot = 0;
int delayed_ack = 1; /* Default is delayed ACKs in use ... */
int delayed_ack_wait = 30000; /* 30 mS before an ACK is generated if */
/* no other traffic */
void
makeseg(char *eth1, char *eth2, char *ip1, char *ip2, char *p1, char *p2, int *s1, int *s2, char *flags, int len)
{
int i;
printf("2002/01/07 00:00:%02d.%06d\n", ts/1000000, ts%1000000);
printf("0000 %s %s 08 00\n", eth1, eth2);
printf("000e 45 00 %02x %02x 00 00 00 00 40 06 00 00 %s %s\n", (len+40)>>8, (len+40)&0xff, ip1, ip2);
printf("0022 %s %s %02x %02x %02x %02x %02x %02x %02x %02x 50 %s 80 00 00 00 00 00", p1, p2,
((*s1)>>24)&0xff,
((*s1)>>16)&0xff,
((*s1)>>8)&0xff,
((*s1))&0xff,
((*s2)>>24)&0xff,
((*s2)>>16)&0xff,
((*s2)>>8)&0xff,
((*s2))&0xff,
flags );
for(i=0;i<(len<(snap_len-40)?len:snap_len-40);i++)printf(" 00");
printf("\n");
printf("\n");
(*s1)+=len;
}
/*
* Figure out when the next ack is due ... here we must skip the acks for
* frames that are marked as ACKs dropped as well as the frames marked as
* frames dropped. These will be marked by the routine that generates ACKs.
* Returns a timestamp value. Returns 2^^31-1 if none are due at all
*/
int next_ack_due()
{
int slot = next_slot;
int ack_lost = 0, seg_lost = 0;
if (next_slot == first_slot)
return (((unsigned int)(1<<31)) - 1);
/*
* Figure out if we need to issue an ACK. We skip all outstanding packets
* that are marked as ack lost or packet lost.
*
* We would not usually come in here with a frame marked as lost or ack lost
* rather, we will come in here and specify that the ack was due at a
* certain time, and gen_next_ack would then determine that the ack
* should be lost or the packet lost.
*/
/*
* Look for a seg slot that is not lost or dropped
*/
while (seg_hist[slot].flags & (SEG_ACK_LOST || SEG_SEG_LOST)) {
if (seg_hist[slot].flags & SEG_ACK_LOST)
ack_lost++;
if (seg_hist[slot].flags & SEG_SEG_LOST)
seg_lost++;
slot = (slot + 1) % SEG_HIST_SIZE;
}
if (slot == next_slot)
return (((unsigned int)(1<<31)) - 1);
/*
* If there is only one slot occupied, or a segment was lost then
* an ACK is due after the last [good] segment left plus ack_delay
*/
if (slot == first_slot && next_slot == ((first_slot + 1) % SEG_HIST_SIZE))
return (seg_hist[first_slot].ts + ack_delay + jitter);
if (seg_lost)
return (seg_hist[slot].ts + ack_delay + jitter);
/*
* OK, now, either we have only seen lost acks, or there are more than
* one outstanding segments, so figure out when the ACK is due.
*
* If delayed ACK is in force, ACK is due after every second seg, but
* if we had a lost ack, then we must ignore 2*lost_ack segments. So,
* if there has not been that many segments sent, we return infinity
* as the next ACK time
*/
if (ack_lost) {
if (delayed_ack) {
if (((first_slot + 1 + 2 * ack_lost) % SEG_HIST_SIZE) >= next_slot)
/* XXX: FIXME, what about when the window is closed */
/* XXX: FIXME, use the correct value for this */
return (((unsigned int)(1<<31)) - 1);
else
return seg_hist[(first_slot + 1 + 2 * ack_lost) % SEG_HIST_SIZE].ts +
ack_delay + jitter;
}
else
return seg_hist[slot].ts + ack_delay + jitter;
}
else {
if (delayed_ack)
return (seg_hist[(first_slot + 1)%SEG_HIST_SIZE].ts+ack_delay+jitter);
else
return (seg_hist[first_slot].ts+ack_delay+jitter);
}
}
/*
* Update the relevant info of the sent seg
*/
add_seg_sent(int seq, int len)
{
/*
* Should check we have not wrapped around and run into the unacked
* stuff ...
*/
/*if (next_slot == first_slot) ;*/
segment++;
seg_hist[next_slot].seq_num = seq;
seg_hist[next_slot].len = len;
seg_hist[next_slot].ts = ts;
seg_hist[next_slot].seg_num = segment;
seg_hist[next_slot].flags = 0;
seg_hist[next_slot].acks_first_seq = 0;
used_win = used_win + len; /* Update the window used */
/*
* Now, update next_slot ...
*/
next_slot = (next_slot + 1) % SEG_HIST_SIZE;
}
/*
* Generate the next ack based on the above reasoning ...
*/
#define NO_FORCE_ACK 0
#define FORCE_ACK 1
/*
* Generate the next ACK. If we did not generate an ACK, return 0,
* else return 1.
*/
int
gen_next_ack(int force, int spacing)
{
int seq_to_ack, new_ts, data_acked;
/*
* We need to check if the segment that we are about to generate an
* ack for is a segment that should be dropped ... or an ack that should
* be dropped.
*
* Figure out what we are doing before freeing segments ...
*/
seq_to_ack = seg_hist[first_slot].seq_num + seg_hist[first_slot].len;
used_win = used_win - seg_hist[first_slot].len;
data_acked = seg_hist[first_slot].len;
new_ts = seg_hist[first_slot].ts + ack_delay;
first_slot = (first_slot + 1) % SEG_HIST_SIZE;
/*
* If delayed ACK in force, then ACK the next segment if there is one
*/
if (delayed_ack && (first_slot != next_slot)) {
seq_to_ack += seg_hist[first_slot].len;
used_win = used_win - seg_hist[first_slot].len;
data_acked += seg_hist[first_slot].len;
new_ts = seg_hist[first_slot].ts + ack_delay;
first_slot = (first_slot + 1) % SEG_HIST_SIZE;
}
/*
* We don't want time to go backward ...
*/
if (new_ts + jitter <= ts)
ts++;
else
ts = new_ts + jitter;
jitter = (rand() % 10 - 5); /* Update jitter ... */
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &seq_to_ack, "10", 0);
/*
* Do we want the exponential part or the linear part?
*/
if (cwnd >= ssthresh)
cwnd += (1460*data_acked)/cwnd; /* is this right? */
else
cwnd = cwnd + data_acked;
if (verbose) fprintf(stderr, "Ack rcvd. ts: %d, data_acked: %d, cwnd: %d, window: %d\n",
ts, data_acked, cwnd, window);
if (cwnd > window) cwnd = window;
}
void
makeackedrun(int len, int spacing, int ackdelay)
{
int next_ack_ts=0;
if (verbose) fprintf(stderr, "makeackedrun: Len=%d, spacing=%d, ackdelay=%d\n",
len, spacing, ackdelay);
while(len>0){
/*
* Each time we output a segment, we should check to see if an
* ack is due back before the next segment is due ...
*/
int seglen, saved_seq;
seglen=(len>1460)?1460:len;
/*
* Only output what is left in the cwnd.
* We assume there is space in the congestion window here
*/
if (seglen > (cwnd - used_win)) seglen = cwnd - used_win;
len-=seglen;
saved_seq = seq_1;
if (verbose) fprintf(stderr, "Sending segment. ts: %d, jitter: %d\n", ts, jitter);
if(len){
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &seq_1, &seq_2, "10", seglen);
} else {
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &seq_1, &seq_2, "18", seglen);
}
add_seg_sent(saved_seq, seglen);
/*
* Now, if the window is closed, then we have to eject an
* ack, otherwise we can eject more data.
* Also, the other end will tend to ack two segments at
* a time ... and that ack might fall between two
* outgoing segments
*/
jitter = (rand()%10) - 5; /* What if spacing too small */
if (verbose) fprintf(stderr, "used win: %d, cwnd: %d\n", used_win, cwnd);
if ((next_ack_ts = next_ack_due()) < ts + spacing + jitter) {
int old_ts = ts;
/*
* Generate the ack and retire the segments
* If delayed ACK in use, there should be two
* or more outstanding segments ...
*/
if (verbose) fprintf(stderr, "Non forced ACK ...ts + spacing + jitter:%d, jitter: %d\n", ts + spacing + jitter, jitter);
gen_next_ack(NO_FORCE_ACK, spacing);
/*
* We don't want time to go backwards ...
*/
if (old_ts + spacing + jitter <= ts)
ts++;
else
ts = old_ts + spacing + jitter;
} else if (used_win == cwnd) {
/*
* We need an ACK, so generate it and retire the
* segments and advance the ts to the time of the ack
*/
if (verbose) fprintf(stderr, "Forced ACK ... \n");
gen_next_ack(FORCE_ACK, spacing);
ts+=(spacing+jitter); /* Should not use spacing here */
}
else {
ts+=(spacing+jitter);
}
if (verbose) fprintf(stderr, "Next Ack Due: %d\n", next_ack_ts);
}
}
void
makeackedrundroppedtail8kb(int len, int spacing, int ackdelay)
{
int old_seq1;
int dropped_tail;
int i;
int num_dupes;
if (verbose) fprintf(stderr, "makeackedrundroppedtail8kB: Len=%d, spacing=%d, ackdelay=%d\n",
len, spacing, ackdelay);
old_seq1=seq_1;
while(len>0){
int seglen;
seglen=(len>1460)?1460:len;
len-=seglen;
if(seglen==1460){
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &seq_1, &seq_2, "10", seglen);
} else {
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &seq_1, &seq_2, "18", seglen);
}
ts+=spacing;
}
ts+=ackdelay;
i=0;
num_dupes=-1;
dropped_tail=0;
while(old_seq1!=seq_1){
int ack_len;
ack_len=((seq_1-old_seq1)>2920)?2920:(seq_1-old_seq1);
i++;
if(i==6){
dropped_tail=old_seq1;
}
old_seq1+=ack_len;
if(i<6){
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &old_seq1, "10", 0);
} else if (i==6) {
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &dropped_tail, "10", 0);
num_dupes+=2;
} else {
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &dropped_tail, "10", 0);
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &dropped_tail, "10", 0);
num_dupes+=2;
}
ts+=spacing/2;
}
if(!dropped_tail){
return;
}
if(num_dupes<3){
int seglen;
ts+=1000000;
seglen=((seq_1-dropped_tail)>1460)?1460:(seq_1-dropped_tail);
if(seglen==1460){
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &dropped_tail, &seq_2, "10", seglen);
} else {
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &dropped_tail, &seq_2, "18", seglen);
}
ts+=ackdelay;
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &seq_1, "10", 0);
ts+=spacing;
return;
}
while(dropped_tail!=seq_1){
int seglen;
int ack;
seglen=((seq_1-dropped_tail)>1460)?1460:(seq_1-dropped_tail);
if(seglen==1460){
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &dropped_tail, &seq_2, "10", seglen);
} else {
makeseg(eth_1, eth_2, ip_1, ip_2, port_1, port_2, &dropped_tail, &seq_2, "18", seglen);
}
ts+=ackdelay;
ack=dropped_tail;
makeseg(eth_2, eth_1, ip_2, ip_1, port_2, port_1, &seq_2, &ack, "10", 0);
ts+=spacing;
}
}
void usage()
{
fprintf(stderr, "Usage: mkcap [OPTIONS], where\n");
fprintf(stderr, "\t-a <ack-delay> is the delay to an ACK (SRT)\n");
fprintf(stderr, "\t-b <bytes-to-send> is the bytes to send on connection\n");
fprintf(stderr, "\t-i <ip-addr-hex> is the sender IP address in hex\n");
fprintf(stderr, "\t-I <ip-addr-hex> is the recipient IP address in hex\n");
fprintf(stderr, "\t-n <ISN> is almost the ISN for the sender\n");
fprintf(stderr, "\t-N <ISN> is almost the ISN for the recipient\n");
fprintf(stderr, "\t-p <port-number-hex> is the port number for sender\n");
fprintf(stderr, "\t-P <port-number-hex> is the port number for recipient\n");
fprintf(stderr, "\t-s <send-spacing> is the send spacing\n");
fprintf(stderr, "\t-w <window-size> is the window size\n");
}
int
all_digits(char *str)
{
int i;
if (!str || !(*str)) {
return 0;
}
for (i = 0; str[i]; i++) {
if (!isdigit(str[i]))
return 0;
}
return 1;
}
/*
* Process a list of drops. These are of the form:
*
* first_seg,seg_count[,first_seg,seg_count]*
*/
void
process_drop_list(char *drop_list)
{
int commas=0;
char *tok, *save;
if (!drop_list || !(*drop_list)) {
fprintf(stderr, "Strange drop list. NULL or an empty string. No drops!\n");
return;
}
save = (char *)g_strdup(drop_list);
for (tok=(char *)strtok(drop_list, ","); tok; tok=(char *)strtok(NULL, ",")) {
commas++;
}
/* Now, we have commas, divide by two and round up */
seg_drop_count = (commas+1)/2;
drops = (seg_drop_t *)g_malloc(sizeof(seg_drop_t) * seg_drop_count);
if (!drops) {
fprintf(stderr, "Unable to allocate space for drops ... going without!\n");
seg_drop_count = 0;
g_free(save);
return;
}
/* Now, go through the list again and build the drop list. Any errors and */
/* we abort and print a usage message */
commas = 0;
for (tok=(char *)strtok(save, ","); tok; tok=(char *)strtok(NULL, ",")) {
int num = atoi(tok);
if (!all_digits(tok)) {
fprintf(stderr, "Error in segment offset or count. Not all digits: %s\n",
tok);
fprintf(stderr, "No packet drops being performed!\n");
g_free(save);
g_free(drops);
seg_drop_count = 0; drops = NULL;
return;
}
if (num == 0) num = 1;
if (commas % 2)
drops[commas / 2].drop_seg_count = num;
else
drops[commas / 2].drop_seg_start = num;
}
g_free(save);
}
int
main(int argc, char *argv[])
{
int i;
int len;
int type;
int cnt;
extern char *optarg;
extern int optind;
int opt;
while ((opt = getopt(argc, argv, "a:b:d:Di:I:j:l:n:N:p:P:r:s:vw:")) != EOF) {
switch (opt) {
case 'a':
ack_delay = atoi(optarg);
break;
case 'b': /* Bytes ... */
total_bytes = atoi(optarg);
break;
case 'd': /* A list of drops to simulate */
process_drop_list(optarg);
break;
case 'D': /* Toggle tcp_nodelay */
tcp_nodelay = (tcp_nodelay + 1) % 1;
break;
case 'i':
ip_1 = optarg;
break;
case 'I':
ip_2 = optarg;
break;
case 'l':
snap_len = atoi(optarg);
break;
case 'n': /* ISN for send dirn, ie, seq_1 */
seq_1 = atoi(optarg);
break;
case 'N': /* ISN for recv dirn, ie, seq_2 */
seq_2 = atoi(optarg);
break;
case 'p':
port_1 = optarg;
break;
case 'P':
port_2 = optarg;
break;
case 'r':
run_type = atoi(optarg);
break;
case 's':
send_spacing = atoi(optarg);
break;
case 'v':
verbose++;
break;
case 'w': /* Window ... */
window = atoi(optarg);
ssthresh = window / 2; /* Have to recalc this ... */
break;
default:
usage();
break;
}
}
if (verbose) fprintf(stderr, "IP1: %s, IP2: %s, P1: %s, P2: %s, Ack Delay: %d, Send Spacing: %d\n",
ip_1, ip_2, port_1, port_2, ack_delay, send_spacing);
/*return 0; */
if (run_type == 0) {
makeackedrun(total_bytes, send_spacing, ack_delay);
}
else {
for(cnt=0;cnt<200;cnt++){
type=rand()%150;
if(type<75){
int j;
j=5+rand()%10;
for(i=0;i<j;i++){
makeackedrun(32768, send_spacing, ack_delay);
}
} else if(type<90) {
int j;
j=4+rand()%4;
for(i=0;i<j;i++){
len=100+rand()&0xfff;
makeackedrun(len, send_spacing, ack_delay);
}
} else {
for(i=0;i<5;i++){
len=100+rand()&0x3fff+0x1fff;
makeackedrun(len, send_spacing, ack_delay);
/*makeackedrundroppedtail8kb(len, send_spacing, ack_delay);*/
}
}
}
}
return 0;
}
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