blob: 72ed8cdb5c36139de3253b6cca42088274a7f758
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 | |
9 | //usage:#define pscan_trivial_usage |
10 | //usage: "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST" |
11 | //usage:#define pscan_full_usage "\n\n" |
12 | //usage: "Scan a host, print all open ports\n" |
13 | //usage: "\n -c Show closed ports too" |
14 | //usage: "\n -b Show blocked ports too" |
15 | //usage: "\n -p Scan from this port (default 1)" |
16 | //usage: "\n -P Scan up to this port (default 1024)" |
17 | //usage: "\n -t Timeout (default 5000 ms)" |
18 | //usage: "\n -T Minimum rtt (default 5 ms, increase for congested hosts)" |
19 | |
20 | #include "libbb.h" |
21 | |
22 | /* debugging */ |
23 | #ifdef DEBUG_PSCAN |
24 | #define DMSG(...) bb_error_msg(__VA_ARGS__) |
25 | #define DERR(...) bb_perror_msg(__VA_ARGS__) |
26 | #else |
27 | #define DMSG(...) ((void)0) |
28 | #define DERR(...) ((void)0) |
29 | #endif |
30 | |
31 | static const char *port_name(unsigned port) |
32 | { |
33 | struct servent *server; |
34 | |
35 | server = getservbyport(htons(port), NULL); |
36 | if (server) |
37 | return server->s_name; |
38 | return "unknown"; |
39 | } |
40 | |
41 | /* We don't expect to see 1000+ seconds delay, unsigned is enough */ |
42 | #define MONOTONIC_US() ((unsigned)monotonic_us()) |
43 | |
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 | |
69 | opt_complementary = "=1"; /* exactly one non-option */ |
70 | opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt); |
71 | argv += optind; |
72 | max_port = xatou_range(opt_max_port, 1, 65535); |
73 | port = xatou_range(opt_min_port, 1, max_port); |
74 | nports = max_port - port + 1; |
75 | min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000; |
76 | timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000; |
77 | /* Initial rtt is BIG: */ |
78 | rtt_4 = timeout; |
79 | |
80 | DMSG("min_rtt %u timeout %u", min_rtt, timeout); |
81 | |
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 | |
86 | for (; port <= max_port; port++) { |
87 | DMSG("rtt %u", rtt_4); |
88 | |
89 | /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */ |
90 | set_nport(&lsap->u.sa, htons(port)); |
91 | s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0); |
92 | /* We need unblocking socket so we don't need to wait for ETIMEOUT. */ |
93 | /* Nonblocking connect typically "fails" with errno == EINPROGRESS */ |
94 | ndelay_on(s); |
95 | |
96 | DMSG("connect to port %u", port); |
97 | result_str = NULL; |
98 | start = MONOTONIC_US(); |
99 | if (connect(s, &lsap->u.sa, lsap->len) == 0) { |
100 | /* Unlikely, for me even localhost fails :) */ |
101 | DMSG("connect succeeded"); |
102 | goto open; |
103 | } |
104 | /* Check for untypical errors... */ |
105 | if (errno != EAGAIN && errno != EINPROGRESS |
106 | && errno != ECONNREFUSED |
107 | ) { |
108 | bb_perror_nomsg_and_die(); |
109 | } |
110 | |
111 | diff = 0; |
112 | while (1) { |
113 | if (errno == ECONNREFUSED) { |
114 | if (opt & 1) /* -c: show closed too */ |
115 | result_str = "closed"; |
116 | closed_ports++; |
117 | break; |
118 | } |
119 | DERR("port %u errno %d @%u", port, errno, diff); |
120 | |
121 | if (diff > rtt_4) { |
122 | if (opt & 2) /* -b: show blocked too */ |
123 | result_str = "blocked"; |
124 | break; |
125 | } |
126 | /* Can sleep (much) longer than specified delay. |
127 | * We check rtt BEFORE we usleep, otherwise |
128 | * on localhost we'll have no writes done (!) |
129 | * before we exceed (rather small) rtt */ |
130 | usleep(rtt_4/8); |
131 | open: |
132 | diff = MONOTONIC_US() - start; |
133 | DMSG("write to port %u @%u", port, diff - start); |
134 | if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */ |
135 | open_ports++; |
136 | result_str = "open"; |
137 | break; |
138 | } |
139 | } |
140 | DMSG("out of loop @%u", diff); |
141 | if (result_str) |
142 | printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n", |
143 | port, result_str, port_name(port)); |
144 | |
145 | /* Estimate new rtt - we don't want to wait entire timeout |
146 | * for each port. *4 allows for rise in net delay. |
147 | * We increase rtt quickly (rtt_4*4), decrease slowly |
148 | * (diff is at least rtt_4/8, *4 == rtt_4/2) |
149 | * because we don't want to accidentally miss ports. */ |
150 | rtt_4 = diff * 4; |
151 | if (rtt_4 < min_rtt) |
152 | rtt_4 = min_rtt; |
153 | if (rtt_4 > timeout) |
154 | rtt_4 = timeout; |
155 | /* Clean up */ |
156 | close(s); |
157 | } |
158 | if (ENABLE_FEATURE_CLEAN_UP) free(lsap); |
159 | |
160 | printf("%u closed, %u open, %u timed out (or blocked) ports\n", |
161 | closed_ports, |
162 | open_ports, |
163 | nports - (closed_ports + open_ports)); |
164 | return EXIT_SUCCESS; |
165 | } |
166 |