/* * Pscan is a mini port scanner implementation for busybox * * Copyright 2007 Tito Ragusa <farmatito@tiscali.it> * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ #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 static const char *port_name(unsigned port) { struct servent *server; server = getservbyport(htons(port), NULL); if (server) return server->s_name; return "unknown"; } /* We don't expect to see 1000+ seconds delay, unsigned is enough */ #define MONOTONIC_US() ((unsigned)monotonic_us()) int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int pscan_main(int argc UNUSED_PARAM, 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 in msec */ /* 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 in msec */ const char *result_str; len_and_sockaddr *lsap; int s; unsigned opt; 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, diff; opt_complementary = "=1"; /* exactly one non-option */ opt = getopt32(argv, "cbp: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, max_port); nports = max_port - port + 1; min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000; timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000; /* Initial rtt is BIG: */ rtt_4 = timeout; 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->u.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); result_str = NULL; start = MONOTONIC_US(); if (connect(s, &lsap->u.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(); } diff = 0; while (1) { if (errno == ECONNREFUSED) { if (opt & 1) /* -c: show closed too */ result_str = "closed"; closed_ports++; break; } DERR("port %u errno %d @%u", port, errno, diff); if (diff > rtt_4) { if (opt & 2) /* -b: show blocked too */ result_str = "blocked"; break; } /* Can sleep (much) longer than specified delay. * We check rtt BEFORE we usleep, otherwise * on localhost we'll have no writes done (!) * before we exceed (rather small) rtt */ usleep(rtt_4/8); open: diff = MONOTONIC_US() - start; DMSG("write to port %u @%u", port, diff - start); if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */ open_ports++; result_str = "open"; break; } } DMSG("out of loop @%u", diff); if (result_str) printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n", port, result_str, port_name(port)); /* 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 (rtt_4*4), decrease slowly * (diff is at least rtt_4/8, *4 == rtt_4/2) * because we don't want to accidentally miss ports. */ rtt_4 = diff * 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 (or blocked) ports\n", closed_ports, open_ports, nports - (closed_ports + open_ports)); return EXIT_SUCCESS; }