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 the GPL v2 or later, see the file LICENSE in this tarball.
   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
  20 static 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
  33 int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  34 int 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 }