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 20static 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 33int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 34int 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} 155