forgot svn add...

networking/pscan.c

@@ -0,0 +1,150 @@
+/*
+ * Pscan is a mini port scanner implementation for busybox
+ *
+ * Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
+ *
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ */
+
+#include "libbb.h"
+
+/* debugging */
+#ifdef DEBUG_PSCAN
+#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 usec */
+// TODO: move to libbb and use in traceroute, zcip, arping etc
+// (maybe also use absolute monotonic clock - no time warps
+// due to admin resetting date/time?)
+static unsigned gettimeofday_us(void)
+{
+	struct timeval now;
+	
+	if (gettimeofday(&now, NULL))
+		return 0;
+	return (now.tv_sec * 1000000 + now.tv_usec);
+}
+
+static const char *port_name(unsigned 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";      /* -P: default max port */
+	const char *opt_min_port = "1";         /* -p: default min port */
+	const char *opt_timeout = "5000";       /* -t: default timeout */
+	/* We estimate rtt and wait rtt*4 before concluding that port is 
+	 * totally blocked. min rtt of 5 ms may be too low if you are
+	 * scanning an Internet host behind saturated/traffic shaped link.
+	 * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
+	 * will take N seconds at absolute minimum */
+	const char *opt_min_rtt = "5";          /* -T: default min rtt */
+	len_and_sockaddr *lsap;
+	int s;
+	unsigned port, max_port, nports;
+	unsigned closed_ports = 0;
+	unsigned open_ports = 0;
+	/* all in usec */
+	unsigned timeout;
+	unsigned min_rtt;
+	unsigned rtt_4;
+	unsigned start;
+
+	opt_complementary = "=1"; /* exactly one non-option */
+	getopt32(argc, argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
+	argv += optind;
+	max_port = xatou_range(opt_max_port, 1, 65535);
+	port = xatou_range(opt_min_port, 1, 65535);
+	nports = max_port - port + 1;
+	if ((int)nports <= 0)
+		bb_show_usage();
+	rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
+	min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
+
+	DMSG("min_rtt %u timeout %u", min_rtt, timeout);
+
+	lsap = xhost2sockaddr(*argv, port);
+	printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
+			*argv, port, max_port);
+
+	for (; port <= max_port; port++) {
+		DMSG("rtt %u", rtt_4);
+
+		/* 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 = gettimeofday_us();
+		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 @%u", port, errno, gettimeofday_us() - start);
+			if ((gettimeofday_us() - start) > rtt_4)
+				break;
+			/* Can sleep (much) longer than specified delay.
+			 * We check rtt BEFORE we usleep, otherwise
+			 * on localhost we'll do zero writes done (!)
+			 * before we exceed (rather small) rtt */
+			usleep(rtt_4/8);
+			DMSG("write to port %u @%u", port, gettimeofday_us() - 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, port_name(port));
+				break;
+			}
+		}
+		DMSG("out of loop @%u", gettimeofday_us() - 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_4 = (gettimeofday_us() - start) * 4;
+		if (rtt_4 < min_rtt)
+			rtt_4 = min_rtt;
+		if (rtt_4 > timeout)
+			rtt_4 = 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,
+					nports - (closed_ports + open_ports));
+	return EXIT_SUCCESS;
+}