139 lines
4.2 KiB
C
139 lines
4.2 KiB
C
/*
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* Pscan is a mini port scanner implementation for busybox
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*
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* Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
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*
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* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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*/
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#include "libbb.h"
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/* debugging */
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#ifdef DEBUG_PSCAN
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#define DMSG(...) bb_error_msg(__VA_ARGS__)
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#define DERR(...) bb_perror_msg(__VA_ARGS__)
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#else
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#define DMSG(...) ((void)0)
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#define DERR(...) ((void)0)
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#endif
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static const char *port_name(unsigned port)
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{
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struct servent *server;
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server = getservbyport(htons(port), NULL);
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if (server)
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return server->s_name;
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return "unknown";
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}
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/* We don't expect to see 1000+ seconds delay, unsigned is enough */
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#define MONOTONIC_US() ((unsigned)monotonic_us())
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int pscan_main(int argc, char **argv);
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int pscan_main(int argc, char **argv)
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{
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const char *opt_max_port = "1024"; /* -P: default max port */
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const char *opt_min_port = "1"; /* -p: default min port */
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const char *opt_timeout = "5000"; /* -t: default timeout in msec */
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/* We estimate rtt and wait rtt*4 before concluding that port is
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* totally blocked. min rtt of 5 ms may be too low if you are
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* scanning an Internet host behind saturated/traffic shaped link.
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* Rule of thumb: with min_rtt of N msec, scanning 1000 ports
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* will take N seconds at absolute minimum */
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const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
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len_and_sockaddr *lsap;
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int s;
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unsigned port, max_port, nports;
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unsigned closed_ports = 0;
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unsigned open_ports = 0;
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/* all in usec */
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unsigned timeout;
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unsigned min_rtt;
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unsigned rtt_4;
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unsigned start;
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opt_complementary = "=1"; /* exactly one non-option */
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getopt32(argc, argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
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argv += optind;
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max_port = xatou_range(opt_max_port, 1, 65535);
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port = xatou_range(opt_min_port, 1, max_port);
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nports = max_port - port + 1;
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rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
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min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
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DMSG("min_rtt %u timeout %u", min_rtt, timeout);
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lsap = xhost2sockaddr(*argv, port);
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printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
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*argv, port, max_port);
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for (; port <= max_port; port++) {
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DMSG("rtt %u", rtt_4);
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/* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
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set_nport(lsap, htons(port));
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s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
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/* We need unblocking socket so we don't need to wait for ETIMEOUT. */
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/* Nonblocking connect typically "fails" with errno == EINPROGRESS */
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ndelay_on(s);
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DMSG("connect to port %u", port);
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start = MONOTONIC_US();
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if (connect(s, &lsap->sa, lsap->len) == 0) {
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/* Unlikely, for me even localhost fails :) */
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DMSG("connect succeeded");
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goto open;
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}
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/* Check for untypical errors... */
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if (errno != EAGAIN && errno != EINPROGRESS
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&& errno != ECONNREFUSED
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) {
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bb_perror_nomsg_and_die();
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}
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while (1) {
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if (errno == ECONNREFUSED) {
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DMSG("port %u: ECONNREFUSED", port);
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closed_ports++;
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break;
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}
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DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
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if ((MONOTONIC_US() - start) > rtt_4)
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break;
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/* Can sleep (much) longer than specified delay.
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* We check rtt BEFORE we usleep, otherwise
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* on localhost we'll do zero writes done (!)
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* before we exceed (rather small) rtt */
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usleep(rtt_4/8);
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DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
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if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
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open:
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open_ports++;
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printf("%5u\ttcp\topen\t%s\n", port, port_name(port));
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break;
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}
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}
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DMSG("out of loop @%u", MONOTONIC_US() - start);
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/* Estimate new rtt - we don't want to wait entire timeout
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* for each port. *4 allows for rise in net delay.
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* We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
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* because we don't want to accidentally miss ports. */
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rtt_4 = (MONOTONIC_US() - start) * 4;
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if (rtt_4 < min_rtt)
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rtt_4 = min_rtt;
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if (rtt_4 > timeout)
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rtt_4 = timeout;
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/* Clean up */
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close(s);
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}
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if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
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printf("%d closed, %d open, %d timed out ports\n",
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closed_ports,
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open_ports,
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nports - (closed_ports + open_ports));
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return EXIT_SUCCESS;
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}
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