On Thursday 14 June 2007 23:27:04 Denis Vlasenko wrote:
> On Thursday 14 June 2007 16:12, Tito wrote:
> > > It's good that you added these comments,
> > > but explanation is not clear enough (at least for me).
> > >
> > > Care to improve?
> > > --
> > > vda
> > >
> >
> > Here a new version of the patch with improved comments. Enjoy! ;-D
> >
> > PS: fixed also a stupid typo in my_gettimeofday
> > if (!gettimeofday(&now, NULL)) ==> if (gettimeofday(&now, NULL))
>
> s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
> ndelay_on(s);
> t1 = my_gettimeofday();
> connect(s, &lsap->sa, lsap->len);
>
> Ok, here it can be successful, or can fail. You don't even look at return
> value.
> It is useless or what?
>
> These questions need to be explained in order to have understandable code.
>
> Ok. I did a small experiment, added a few debug prints,
> and changed it to start scanning from port 79.
>
> # ./busybox pscan -p 80 195.66.192.167 2>2
> Scanning 195.66.192.167 ports 1 to 80
> Port Proto State Service
> 80 tcp open www
> 78 stealth, 1 closed, 1 open ports
>
> logfile:
>
> pscan: connect 45us: Operation now in progress
> pscan: write:-1 4us
> pscan: write:-1 2us
> <15759 more write errors snipped>
> pscan: connect 31us: Operation now in progress
> pscan: write:-1 2us
> <~140000 more write errors snipped>
> pscan: write:1 18us
>
> I don't like write() flood, with accompanying horde of gettimeofday calls.
>
> Maybe this? (please see attched).
> --
> vda
>
Looks good to me, added some of the TODOs and changed all the time to msec.
Please check if i fully understood your code. Sorry no time for a patch right
now,
sending the file I've changed. If needed patch will follow tomorrow. ;-)
Ciao,
Tito
PS: change usage.h to
#define pscan_trivial_usage \
"[-p MIN_PORT][-P MAX_PORT][-t MIN_RTT][-T TIMEOUT] HOST"
#define pscan_full_usage \
" Scan a host's ports printing all open ports." \
"\n\nOptions:\n" \
" -p scan from this port (default 1)\n" \
" -P scan up to this port (default 1024)\n" \
" -t minimum roundtrip time in msec (default 1000)"\
" -T timeout in msecs (default 5000)"
/*
* Pscan is a mini port scanner implementation for busybox
*
* Copyright 2007 Tito Ragusa <[EMAIL PROTECTED]>
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include "libbb.h"
/* debugging */
#ifdef DEBUG
#define DMSG(...) bb_error_msg(__VA_ARGS__)
#define DERR(...) bb_perror_msg(__VA_ARGS__)
#else
#define DMSG(...) ((void)0)
#define DERR(...) ((void)0)
#endif
/* return time in msec */
static unsigned long my_gettimeofday(void)
{
struct timeval now;
if (gettimeofday(&now, NULL))
return 0;
return (now.tv_sec * 1000 + now.tv_usec / 1000);
}
static const char *my_getservbyport(int port)
{
struct servent *server;
server = getservbyport(htons(port), NULL);
if (server)
return server->s_name;
return "unknown";
}
int pscan_main( int argc, char **argv);
int pscan_main( int argc, char **argv)
{
const char *opt_max_port = "1024"; /* default max port */
const char *opt_min_port = "1"; /* default min port */
const char *opt_max_timeout = "5000"; /* arbitrary default max timeout for roundtrip: 5000 mseconds */
const char *opt_min_timeout = "1000"; /* arbitrary default max timeout for roundtrip: 1000 mseconds */
unsigned port;
unsigned max_port;
unsigned closed_ports = 0;
unsigned open_ports = 0;
long unsigned timeout; /* in us */
long unsigned min_timeout; /* in us */
long unsigned rtt; /* in us */
long unsigned start; /* in us */
int s;
len_and_sockaddr *lsap;
opt_complementary = "-1";
getopt32(argc, argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_max_timeout, &opt_min_timeout);
max_port = xatou_range(opt_max_port, 1, 65535);
port = xatou_range(opt_min_port, 1, 65535);
rtt = timeout = xatou_range(opt_max_timeout, 1, ULONG_MAX);
min_timeout = xatou_range(opt_min_timeout, 1, ULONG_MAX);
argv += optind;
lsap = xhost2sockaddr(*argv, port);
printf("Scanning %s ports 1 to %d\n Port\tProto\tState\tService\n", *argv, max_port);
for (; port <= max_port; port++) {
DMSG("rtt %lu", rtt);
/* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
set_nport(lsap, htons(port));
s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
/* We need unblocking socket so we don't need to wait for ETIMEOUT. */
/* Nonblocking connect typically "fails" with errno == EINPROGRESS */
ndelay_on(s);
DMSG("connect to port %u", port);
start = my_gettimeofday();
if (connect(s, &lsap->sa, lsap->len) == 0) {
/* Unlikely, for me even localhost fails :) */
DMSG("connect succeeded");
goto open;
}
/* Check for untypical errors... */
if (errno != EAGAIN && errno != EINPROGRESS
&& errno != ECONNREFUSED
) {
bb_perror_nomsg_and_die();
}
while (1) {
if (errno == ECONNREFUSED) {
DMSG("port %u: ECONNREFUSED", port);
closed_ports++;
break;
}
DERR("port %u errno %d @%lu", port, errno, my_gettimeofday() - start);
if ((my_gettimeofday() - start) > rtt)
break;
/* Can sleep (much) longer than this.
* We check rtt BEFORE we usleep, otherwise
* on localhost we'll do zero writes done (!)
* before we exceed (rather small) rtt */
usleep(rtt/8);
DMSG("write to port %u @%lu", port, my_gettimeofday() - start);
if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
open:
open_ports++;
printf("%5u\ttcp\topen\t%s\n", port, my_getservbyport(port));
break;
}
}
DMSG("out of loop @%lu", my_gettimeofday() - start);
/* Estimate new rtt - we don't want to wait entire timeout
* for each port. *4 allows for rise in net delay.
* We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
* because we don't want to accidentally miss ports. */
rtt = (my_gettimeofday() - start) * 4;
if (rtt < min_timeout)
rtt = min_timeout;
if (rtt > timeout)
rtt = timeout;
/* Clean up */
close(s);
}
if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
printf("%d closed, %d open, %d timed out ports\n",
closed_ports,
open_ports,
max_port - (closed_ports + open_ports));
return EXIT_SUCCESS;
}
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