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 the GPL v2 or later, see the file LICENSE in this tarball.
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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);
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34 | int pscan_main(int argc, 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 | len_and_sockaddr *lsap;
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46 | int s;
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47 | unsigned port, max_port, nports;
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48 | unsigned closed_ports = 0;
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49 | unsigned open_ports = 0;
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50 | /* all in usec */
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51 | unsigned timeout;
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52 | unsigned min_rtt;
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53 | unsigned rtt_4;
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54 | unsigned start;
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55 |
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56 | opt_complementary = "=1"; /* exactly one non-option */
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57 | getopt32(argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
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58 | argv += optind;
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59 | max_port = xatou_range(opt_max_port, 1, 65535);
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60 | port = xatou_range(opt_min_port, 1, max_port);
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61 | nports = max_port - port + 1;
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62 | rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
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63 | min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
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64 |
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65 | DMSG("min_rtt %u timeout %u", min_rtt, timeout);
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66 |
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67 | lsap = xhost2sockaddr(*argv, port);
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68 | printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
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69 | *argv, port, max_port);
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70 |
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71 | for (; port <= max_port; port++) {
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72 | DMSG("rtt %u", rtt_4);
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73 |
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74 | /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
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75 | set_nport(lsap, htons(port));
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76 | s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
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77 |
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78 | /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
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79 | /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
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80 | ndelay_on(s);
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81 | DMSG("connect to port %u", port);
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82 | start = MONOTONIC_US();
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83 | if (connect(s, &lsap->sa, lsap->len) == 0) {
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84 | /* Unlikely, for me even localhost fails :) */
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85 | DMSG("connect succeeded");
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86 | goto open;
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87 | }
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88 | /* Check for untypical errors... */
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89 | if (errno != EAGAIN && errno != EINPROGRESS
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90 | && errno != ECONNREFUSED
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91 | ) {
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92 | bb_perror_nomsg_and_die();
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93 | }
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94 |
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95 | while (1) {
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96 | if (errno == ECONNREFUSED) {
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97 | DMSG("port %u: ECONNREFUSED", port);
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98 | closed_ports++;
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99 | break;
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100 | }
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101 | DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
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102 | if ((MONOTONIC_US() - start) > rtt_4)
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103 | break;
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104 | /* Can sleep (much) longer than specified delay.
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105 | * We check rtt BEFORE we usleep, otherwise
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106 | * on localhost we'll do zero writes done (!)
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107 | * before we exceed (rather small) rtt */
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108 | usleep(rtt_4/8);
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109 | DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
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110 | if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
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111 | open:
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112 | open_ports++;
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113 | printf("%5u\ttcp\topen\t%s\n", port, port_name(port));
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114 | break;
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115 | }
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116 | }
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117 | DMSG("out of loop @%u", MONOTONIC_US() - start);
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118 |
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119 | /* Estimate new rtt - we don't want to wait entire timeout
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120 | * for each port. *4 allows for rise in net delay.
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121 | * We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
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122 | * because we don't want to accidentally miss ports. */
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123 | rtt_4 = (MONOTONIC_US() - start) * 4;
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124 | if (rtt_4 < min_rtt)
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125 | rtt_4 = min_rtt;
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126 | if (rtt_4 > timeout)
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127 | rtt_4 = timeout;
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128 | /* Clean up */
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129 | close(s);
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130 | }
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131 | if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
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132 |
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133 | printf("%d closed, %d open, %d timed out ports\n",
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134 | closed_ports,
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135 | open_ports,
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136 | nports - (closed_ports + open_ports));
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137 | return EXIT_SUCCESS;
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138 | }
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