release/src/router/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 //usage:#define pscan_trivial_usage
  10 //usage:       "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
  11 //usage:#define pscan_full_usage "\n\n"
  12 //usage:       "Scan a host, print all open ports\n"
  13 //usage:     "\n        -c      Show closed ports too"
  14 //usage:     "\n        -b      Show blocked ports too"
  15 //usage:     "\n        -p      Scan from this port (default 1)"
  16 //usage:     "\n        -P      Scan up to this port (default 1024)"
  17 //usage:     "\n        -t      Timeout (default 5000 ms)"
  18 //usage:     "\n        -T      Minimum rtt (default 5 ms, increase for congested hosts)"
  19
  20 #include "libbb.h"
  21
  22 /* debugging */
  23 #ifdef DEBUG_PSCAN
  24 #define DMSG(...) bb_error_msg(__VA_ARGS__)
  25 #define DERR(...) bb_perror_msg(__VA_ARGS__)
  26 #else
  27 #define DMSG(...) ((void)0)
  28 #define DERR(...) ((void)0)
  29 #endif
  30
  31 static const char *port_name(unsigned port)
  32 {
  33         struct servent *server;
  34
  35         server = getservbyport(htons(port), NULL);
  36         if (server)
  37                 return server->s_name;
  38         return "unknown";
  39 }
  40
  41 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  42 #define MONOTONIC_US() ((unsigned)monotonic_us())
  43
  44 int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  45 int pscan_main(int argc UNUSED_PARAM, char **argv)
  46 {
  47         const char *opt_max_port = "1024";      /* -P: default max port */
  48         const char *opt_min_port = "1";         /* -p: default min port */
  49         const char *opt_timeout = "5000";       /* -t: default timeout in msec */
  50         /* We estimate rtt and wait rtt*4 before concluding that port is
  51          * totally blocked. min rtt of 5 ms may be too low if you are
  52          * scanning an Internet host behind saturated/traffic shaped link.
  53          * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
  54          * will take N seconds at absolute minimum */
  55         const char *opt_min_rtt = "5";          /* -T: default min rtt in msec */
  56         const char *result_str;
  57         len_and_sockaddr *lsap;
  58         int s;
  59         unsigned opt;
  60         unsigned port, max_port, nports;
  61         unsigned closed_ports = 0;
  62         unsigned open_ports = 0;
  63         /* all in usec */
  64         unsigned timeout;
  65         unsigned min_rtt;
  66         unsigned rtt_4;
  67         unsigned start, diff;
  68
  69         opt_complementary = "=1"; /* exactly one non-option */
  70         opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
  71         argv += optind;
  72         max_port = xatou_range(opt_max_port, 1, 65535);
  73         port = xatou_range(opt_min_port, 1, max_port);
  74         nports = max_port - port + 1;
  75         min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
  76         timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
  77         /* Initial rtt is BIG: */
  78         rtt_4 = timeout;
  79
  80         DMSG("min_rtt %u timeout %u", min_rtt, timeout);
  81
  82         lsap = xhost2sockaddr(*argv, port);
  83         printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
  84                         *argv, port, max_port);
  85
  86         for (; port <= max_port; port++) {
  87                 DMSG("rtt %u", rtt_4);
  88
  89                 /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
  90                 set_nport(&lsap->u.sa, htons(port));
  91                 s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
  92                 /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
  93                 /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
  94                 ndelay_on(s);
  95
  96                 DMSG("connect to port %u", port);
  97                 result_str = NULL;
  98                 start = MONOTONIC_US();
  99                 if (connect(s, &lsap->u.sa, lsap->len) == 0) {
 100                         /* Unlikely, for me even localhost fails :) */
 101                         DMSG("connect succeeded");
 102                         goto open;
 103                 }
 104                 /* Check for untypical errors... */
 105                 if (errno != EAGAIN && errno != EINPROGRESS
 106                  && errno != ECONNREFUSED
 107                 ) {
 108                         bb_perror_nomsg_and_die();
 109                 }
 110
 111                 diff = 0;
 112                 while (1) {
 113                         if (errno == ECONNREFUSED) {
 114                                 if (opt & 1) /* -c: show closed too */
 115                                         result_str = "closed";
 116                                 closed_ports++;
 117                                 break;
 118                         }
 119                         DERR("port %u errno %d @%u", port, errno, diff);
 120
 121                         if (diff > rtt_4) {
 122                                 if (opt & 2) /* -b: show blocked too */
 123                                         result_str = "blocked";
 124                                 break;
 125                         }
 126                         /* Can sleep (much) longer than specified delay.
 127                          * We check rtt BEFORE we usleep, otherwise
 128                          * on localhost we'll have no writes done (!)
 129                          * before we exceed (rather small) rtt */
 130                         usleep(rtt_4/8);
 131  open:
 132                         diff = MONOTONIC_US() - start;
 133                         DMSG("write to port %u @%u", port, diff - start);
 134                         if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
 135                                 open_ports++;
 136                                 result_str = "open";
 137                                 break;
 138                         }
 139                 }
 140                 DMSG("out of loop @%u", diff);
 141                 if (result_str)
 142                         printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
 143                                         port, result_str, port_name(port));
 144
 145                 /* Estimate new rtt - we don't want to wait entire timeout
 146                  * for each port. *4 allows for rise in net delay.
 147                  * We increase rtt quickly (rtt_4*4), decrease slowly
 148                  * (diff is at least rtt_4/8, *4 == rtt_4/2)
 149                  * because we don't want to accidentally miss ports. */
 150                 rtt_4 = diff * 4;
 151                 if (rtt_4 < min_rtt)
 152                         rtt_4 = min_rtt;
 153                 if (rtt_4 > timeout)
 154                         rtt_4 = timeout;
 155                 /* Clean up */
 156                 close(s);
 157         }
 158         if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
 159
 160         printf("%d closed, %d open, %d timed out (or blocked) ports\n",
 161                                         closed_ports,
 162                                         open_ports,
 163                                         nports - (closed_ports + open_ports));
 164         return EXIT_SUCCESS;
 165 }