pscan.c 5.3 KB

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  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. //config:config PSCAN
  9. //config: bool "pscan (6.6 kb)"
  10. //config: default y
  11. //config: help
  12. //config: Simple network port scanner.
  13. //applet:IF_PSCAN(APPLET(pscan, BB_DIR_USR_BIN, BB_SUID_DROP))
  14. //kbuild:lib-$(CONFIG_PSCAN) += pscan.o
  15. //usage:#define pscan_trivial_usage
  16. //usage: "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
  17. //usage:#define pscan_full_usage "\n\n"
  18. //usage: "Scan a host, print all open ports\n"
  19. //usage: "\n -c Show closed ports too"
  20. //usage: "\n -b Show blocked ports too"
  21. //usage: "\n -p Scan from this port (default 1)"
  22. //usage: "\n -P Scan up to this port (default 1024)"
  23. //usage: "\n -t Timeout (default 5000 ms)"
  24. //usage: "\n -T Minimum rtt (default 5 ms, increase for congested hosts)"
  25. #include "libbb.h"
  26. /* debugging */
  27. #ifdef DEBUG_PSCAN
  28. #define DMSG(...) bb_error_msg(__VA_ARGS__)
  29. #define DERR(...) bb_perror_msg(__VA_ARGS__)
  30. #else
  31. #define DMSG(...) ((void)0)
  32. #define DERR(...) ((void)0)
  33. #endif
  34. static const char *port_name(unsigned port)
  35. {
  36. struct servent *server;
  37. server = getservbyport(htons(port), NULL);
  38. if (server)
  39. return server->s_name;
  40. return "unknown";
  41. }
  42. /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  43. #define MONOTONIC_US() ((unsigned)monotonic_us())
  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. opt = getopt32(argv, "^"
  69. "cbp:P:t:T:"
  70. "\0" "=1", /* exactly one non-option */
  71. &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt
  72. );
  73. argv += optind;
  74. max_port = xatou_range(opt_max_port, 1, 65535);
  75. port = xatou_range(opt_min_port, 1, max_port);
  76. nports = max_port - port + 1;
  77. min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
  78. timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
  79. /* Initial rtt is BIG: */
  80. rtt_4 = timeout;
  81. DMSG("min_rtt %u timeout %u", min_rtt, timeout);
  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. for (; port <= max_port; port++) {
  86. DMSG("rtt %u", rtt_4);
  87. /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
  88. set_nport(&lsap->u.sa, htons(port));
  89. s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
  90. /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
  91. /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
  92. ndelay_on(s);
  93. DMSG("connect to port %u", port);
  94. result_str = NULL;
  95. start = MONOTONIC_US();
  96. if (connect(s, &lsap->u.sa, lsap->len) == 0) {
  97. /* Unlikely, for me even localhost fails :) */
  98. DMSG("connect succeeded");
  99. goto open;
  100. }
  101. /* Check for untypical errors... */
  102. if (errno != EAGAIN && errno != EINPROGRESS
  103. && errno != ECONNREFUSED
  104. ) {
  105. bb_perror_nomsg_and_die();
  106. }
  107. diff = 0;
  108. while (1) {
  109. if (errno == ECONNREFUSED) {
  110. if (opt & 1) /* -c: show closed too */
  111. result_str = "closed";
  112. closed_ports++;
  113. break;
  114. }
  115. DERR("port %u errno %d @%u", port, errno, diff);
  116. if (diff > rtt_4) {
  117. if (opt & 2) /* -b: show blocked too */
  118. result_str = "blocked";
  119. break;
  120. }
  121. /* Can sleep (much) longer than specified delay.
  122. * We check rtt BEFORE we usleep, otherwise
  123. * on localhost we'll have no writes done (!)
  124. * before we exceed (rather small) rtt */
  125. usleep(rtt_4/8);
  126. open:
  127. diff = MONOTONIC_US() - start;
  128. DMSG("write to port %u @%u", port, diff - start);
  129. if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
  130. open_ports++;
  131. result_str = "open";
  132. break;
  133. }
  134. }
  135. DMSG("out of loop @%u", diff);
  136. if (result_str)
  137. printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
  138. port, result_str, port_name(port));
  139. /* Estimate new rtt - we don't want to wait entire timeout
  140. * for each port. *4 allows for rise in net delay.
  141. * We increase rtt quickly (rtt_4*4), decrease slowly
  142. * (diff is at least rtt_4/8, *4 == rtt_4/2)
  143. * because we don't want to accidentally miss ports. */
  144. rtt_4 = diff * 4;
  145. if (rtt_4 < min_rtt)
  146. rtt_4 = min_rtt;
  147. if (rtt_4 > timeout)
  148. rtt_4 = timeout;
  149. /* Clean up */
  150. close(s);
  151. }
  152. if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
  153. printf("%u closed, %u open, %u timed out (or blocked) ports\n",
  154. closed_ports,
  155. open_ports,
  156. nports - (closed_ports + open_ports));
  157. return EXIT_SUCCESS;
  158. }