[3320] | 1 | /*
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| 2 | * Pscan is a mini port scanner implementation for busybox
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| 3 | *
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| 4 | * Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
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| 5 | *
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| 6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 7 | */
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| 8 |
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| 9 | #include "libbb.h"
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| 10 |
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| 11 | /* debugging */
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| 12 | #ifdef DEBUG_PSCAN
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| 13 | #define DMSG(...) bb_error_msg(__VA_ARGS__)
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| 14 | #define DERR(...) bb_perror_msg(__VA_ARGS__)
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| 15 | #else
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| 16 | #define DMSG(...) ((void)0)
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| 17 | #define DERR(...) ((void)0)
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| 18 | #endif
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| 19 |
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| 20 | static const char *port_name(unsigned port)
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| 21 | {
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| 22 | struct servent *server;
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| 23 |
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| 24 | server = getservbyport(htons(port), NULL);
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| 25 | if (server)
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| 26 | return server->s_name;
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| 27 | return "unknown";
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| 28 | }
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| 29 |
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| 30 | /* We don't expect to see 1000+ seconds delay, unsigned is enough */
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| 31 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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| 32 |
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| 33 | int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 34 | int pscan_main(int argc UNUSED_PARAM, char **argv)
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| 35 | {
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| 36 | const char *opt_max_port = "1024"; /* -P: default max port */
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| 37 | const char *opt_min_port = "1"; /* -p: default min port */
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| 38 | const char *opt_timeout = "5000"; /* -t: default timeout in msec */
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| 39 | /* We estimate rtt and wait rtt*4 before concluding that port is
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| 40 | * totally blocked. min rtt of 5 ms may be too low if you are
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| 41 | * scanning an Internet host behind saturated/traffic shaped link.
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| 42 | * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
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| 43 | * will take N seconds at absolute minimum */
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| 44 | const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
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| 45 | const char *result_str;
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| 46 | len_and_sockaddr *lsap;
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| 47 | int s;
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| 48 | unsigned opt;
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| 49 | unsigned port, max_port, nports;
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| 50 | unsigned closed_ports = 0;
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| 51 | unsigned open_ports = 0;
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| 52 | /* all in usec */
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| 53 | unsigned timeout;
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| 54 | unsigned min_rtt;
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| 55 | unsigned rtt_4;
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| 56 | unsigned start, diff;
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| 57 |
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| 58 | opt_complementary = "=1"; /* exactly one non-option */
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| 59 | opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
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| 60 | argv += optind;
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| 61 | max_port = xatou_range(opt_max_port, 1, 65535);
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| 62 | port = xatou_range(opt_min_port, 1, max_port);
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| 63 | nports = max_port - port + 1;
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| 64 | min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
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| 65 | timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
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| 66 | /* Initial rtt is BIG: */
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| 67 | rtt_4 = timeout;
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| 68 |
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| 69 | DMSG("min_rtt %u timeout %u", min_rtt, timeout);
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| 70 |
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| 71 | lsap = xhost2sockaddr(*argv, port);
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| 72 | printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
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| 73 | *argv, port, max_port);
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| 74 |
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| 75 | for (; port <= max_port; port++) {
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| 76 | DMSG("rtt %u", rtt_4);
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| 77 |
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| 78 | /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
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| 79 | set_nport(lsap, htons(port));
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| 80 | s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
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| 81 | /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
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| 82 | /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
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| 83 | ndelay_on(s);
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| 84 |
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| 85 | DMSG("connect to port %u", port);
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| 86 | result_str = NULL;
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| 87 | start = MONOTONIC_US();
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| 88 | if (connect(s, &lsap->u.sa, lsap->len) == 0) {
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| 89 | /* Unlikely, for me even localhost fails :) */
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| 90 | DMSG("connect succeeded");
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| 91 | goto open;
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| 92 | }
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| 93 | /* Check for untypical errors... */
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| 94 | if (errno != EAGAIN && errno != EINPROGRESS
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| 95 | && errno != ECONNREFUSED
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| 96 | ) {
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| 97 | bb_perror_nomsg_and_die();
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| 98 | }
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| 99 |
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| 100 | diff = 0;
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| 101 | while (1) {
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| 102 | if (errno == ECONNREFUSED) {
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| 103 | if (opt & 1) /* -c: show closed too */
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| 104 | result_str = "closed";
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| 105 | closed_ports++;
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| 106 | break;
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| 107 | }
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| 108 | DERR("port %u errno %d @%u", port, errno, diff);
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| 109 |
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| 110 | if (diff > rtt_4) {
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| 111 | if (opt & 2) /* -b: show blocked too */
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| 112 | result_str = "blocked";
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| 113 | break;
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| 114 | }
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| 115 | /* Can sleep (much) longer than specified delay.
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| 116 | * We check rtt BEFORE we usleep, otherwise
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| 117 | * on localhost we'll have no writes done (!)
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| 118 | * before we exceed (rather small) rtt */
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| 119 | usleep(rtt_4/8);
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| 120 | open:
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| 121 | diff = MONOTONIC_US() - start;
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| 122 | DMSG("write to port %u @%u", port, diff - start);
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| 123 | if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
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| 124 | open_ports++;
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| 125 | result_str = "open";
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| 126 | break;
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| 127 | }
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| 128 | }
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| 129 | DMSG("out of loop @%u", diff);
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| 130 | if (result_str)
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| 131 | printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
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| 132 | port, result_str, port_name(port));
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| 133 |
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| 134 | /* Estimate new rtt - we don't want to wait entire timeout
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| 135 | * for each port. *4 allows for rise in net delay.
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| 136 | * We increase rtt quickly (rtt_4*4), decrease slowly
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| 137 | * (diff is at least rtt_4/8, *4 == rtt_4/2)
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| 138 | * because we don't want to accidentally miss ports. */
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| 139 | rtt_4 = diff * 4;
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| 140 | if (rtt_4 < min_rtt)
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| 141 | rtt_4 = min_rtt;
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| 142 | if (rtt_4 > timeout)
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| 143 | rtt_4 = timeout;
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| 144 | /* Clean up */
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| 145 | close(s);
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| 146 | }
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| 147 | if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
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| 148 |
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| 149 | printf("%d closed, %d open, %d timed out (or blocked) ports\n",
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| 150 | closed_ports,
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| 151 | open_ports,
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| 152 | nports - (closed_ports + open_ports));
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| 153 | return EXIT_SUCCESS;
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| 154 | }
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