LXR busybox/networking/pscan.c

   1/*
   2 * Pscan is a mini port scanner implementation for busybox
   3 *
   4 * Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
   5 *
   6 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   7 */
   8
   9#include "libbb.h"
  10
  11/* debugging */
  12#ifdef DEBUG_PSCAN
  13#define DMSG(...) bb_error_msg(__VA_ARGS__)
  14#define DERR(...) bb_perror_msg(__VA_ARGS__)
  15#else
  16#define DMSG(...) ((void)0)
  17#define DERR(...) ((void)0)
  18#endif
  19
  20static const char *port_name(unsigned port)
  21{
  22        struct servent *server;
  23
  24        server = getservbyport(htons(port), NULL);
  25        if (server)
  26                return server->s_name;
  27        return "unknown";
  28}
  29
  30/* We don't expect to see 1000+ seconds delay, unsigned is enough */
  31#define MONOTONIC_US() ((unsigned)monotonic_us())
  32
  33int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  34int pscan_main(int argc UNUSED_PARAM, char **argv)
  35{
  36        const char *opt_max_port = "1024";      /* -P: default max port */
  37        const char *opt_min_port = "1";         /* -p: default min port */
  38        const char *opt_timeout = "5000";       /* -t: default timeout in msec */
  39        /* We estimate rtt and wait rtt*4 before concluding that port is
  40         * totally blocked. min rtt of 5 ms may be too low if you are
  41         * scanning an Internet host behind saturated/traffic shaped link.
  42         * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
  43         * will take N seconds at absolute minimum */
  44        const char *opt_min_rtt = "5";          /* -T: default min rtt in msec */
  45        const char *result_str;
  46        len_and_sockaddr *lsap;
  47        int s;
  48        unsigned opt;
  49        unsigned port, max_port, nports;
  50        unsigned closed_ports = 0;
  51        unsigned open_ports = 0;
  52        /* all in usec */
  53        unsigned timeout;
  54        unsigned min_rtt;
  55        unsigned rtt_4;
  56        unsigned start, diff;
  57
  58        opt_complementary = "=1"; /* exactly one non-option */
  59        opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
  60        argv += optind;
  61        max_port = xatou_range(opt_max_port, 1, 65535);
  62        port = xatou_range(opt_min_port, 1, max_port);
  63        nports = max_port - port + 1;
  64        min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
  65        timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
  66        /* Initial rtt is BIG: */
  67        rtt_4 = timeout;
  68
  69        DMSG("min_rtt %u timeout %u", min_rtt, timeout);
  70
  71        lsap = xhost2sockaddr(*argv, port);
  72        printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
  73                        *argv, port, max_port);
  74
  75        for (; port <= max_port; port++) {
  76                DMSG("rtt %u", rtt_4);
  77
  78                /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
  79                set_nport(lsap, htons(port));
  80                s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
  81                /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
  82                /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
  83                ndelay_on(s);
  84
  85                DMSG("connect to port %u", port);
  86                result_str = NULL;
  87                start = MONOTONIC_US();
  88                if (connect(s, &lsap->u.sa, lsap->len) == 0) {
  89                        /* Unlikely, for me even localhost fails :) */
  90                        DMSG("connect succeeded");
  91                        goto open;
  92                }
  93                /* Check for untypical errors... */
  94                if (errno != EAGAIN && errno != EINPROGRESS
  95                 && errno != ECONNREFUSED
  96                ) {
  97                        bb_perror_nomsg_and_die();
  98                }
  99
 100                diff = 0;
 101                while (1) {
 102                        if (errno == ECONNREFUSED) {
 103                                if (opt & 1) /* -c: show closed too */
 104                                        result_str = "closed";
 105                                closed_ports++;
 106                                break;
 107                        }
 108                        DERR("port %u errno %d @%u", port, errno, diff);
 109
 110                        if (diff > rtt_4) {
 111                                if (opt & 2) /* -b: show blocked too */
 112                                        result_str = "blocked";
 113                                break;
 114                        }
 115                        /* Can sleep (much) longer than specified delay.
 116                         * We check rtt BEFORE we usleep, otherwise
 117                         * on localhost we'll have no writes done (!)
 118                         * before we exceed (rather small) rtt */
 119                        usleep(rtt_4/8);
 120 open:
 121                        diff = MONOTONIC_US() - start;
 122                        DMSG("write to port %u @%u", port, diff - start);
 123                        if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
 124                                open_ports++;
 125                                result_str = "open";
 126                                break;
 127                        }
 128                }
 129                DMSG("out of loop @%u", diff);
 130                if (result_str)
 131                        printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
 132                                        port, result_str, port_name(port));
 133
 134                /* Estimate new rtt - we don't want to wait entire timeout
 135                 * for each port. *4 allows for rise in net delay.
 136                 * We increase rtt quickly (rtt_4*4), decrease slowly
 137                 * (diff is at least rtt_4/8, *4 == rtt_4/2)
 138                 * because we don't want to accidentally miss ports. */
 139                rtt_4 = diff * 4;
 140                if (rtt_4 < min_rtt)
 141                        rtt_4 = min_rtt;
 142                if (rtt_4 > timeout)
 143                        rtt_4 = timeout;
 144                /* Clean up */
 145                close(s);
 146        }
 147        if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
 148
 149        printf("%d closed, %d open, %d timed out (or blocked) ports\n",
 150                                        closed_ports,
 151                                        open_ports,
 152                                        nports - (closed_ports + open_ports));
 153        return EXIT_SUCCESS;
 154}
 155