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 kb)"
10 //config: default y
11 //config: help
12 //config: Simple network port scanner.
13
14 //applet:IF_PSCAN(APPLET(pscan, BB_DIR_USR_BIN, BB_SUID_DROP))
15
16 //kbuild:lib-$(CONFIG_PSCAN) += pscan.o
17
18 //usage:#define pscan_trivial_usage
19 //usage: "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
20 //usage:#define pscan_full_usage "\n\n"
21 //usage: "Scan HOST, print all open ports\n"
22 //usage: "\n -c Show closed ports too"
23 //usage: "\n -b Show blocked ports too"
24 //usage: "\n -p PORT Scan from this port (default 1)"
25 //usage: "\n -P PORT Scan up to this port (default 1024)"
26 //usage: "\n -t MS Timeout (default 5000 ms)"
27 //usage: "\n -T MS Minimum rtt (default 5 ms)"
28
29 #include "libbb.h"
30
31 /* debugging */
32 #ifdef DEBUG_PSCAN
33 #define DMSG(...) bb_error_msg(__VA_ARGS__)
34 #define DERR(...) bb_perror_msg(__VA_ARGS__)
35 #else
36 #define DMSG(...) ((void)0)
37 #define DERR(...) ((void)0)
38 #endif
39
port_name(unsigned port)40 static const char *port_name(unsigned port)
41 {
42 struct servent *server;
43
44 server = getservbyport(htons(port), NULL);
45 if (server)
46 return server->s_name;
47 return "unknown";
48 }
49
50 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
51 #define MONOTONIC_US() ((unsigned)monotonic_us())
52
53 int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
pscan_main(int argc UNUSED_PARAM,char ** argv)54 int pscan_main(int argc UNUSED_PARAM, char **argv)
55 {
56 const char *opt_max_port = "1024"; /* -P: default max port */
57 const char *opt_min_port = "1"; /* -p: default min port */
58 const char *opt_timeout = "5000"; /* -t: default timeout in msec */
59 /* We estimate rtt and wait rtt*4 before concluding that port is
60 * totally blocked. min rtt of 5 ms may be too low if you are
61 * scanning an Internet host behind saturated/traffic shaped link.
62 * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
63 * will take N seconds at absolute minimum */
64 const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
65 const char *result_str;
66 len_and_sockaddr *lsap;
67 int s;
68 unsigned opt;
69 unsigned port, max_port, nports;
70 unsigned closed_ports = 0;
71 unsigned open_ports = 0;
72 /* all in usec */
73 unsigned timeout;
74 unsigned min_rtt;
75 unsigned rtt_4;
76 unsigned start, diff;
77
78 opt = getopt32(argv, "^"
79 "cbp:P:t:T:"
80 "\0" "=1", /* exactly one non-option */
81 &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt
82 );
83 argv += optind;
84 max_port = xatou_range(opt_max_port, 1, 65535);
85 port = xatou_range(opt_min_port, 1, max_port);
86 nports = max_port - port + 1;
87 min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
88 timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
89 /* Initial rtt is BIG: */
90 rtt_4 = timeout;
91
92 DMSG("min_rtt %u timeout %u", min_rtt, timeout);
93
94 lsap = xhost2sockaddr(*argv, port);
95 printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
96 *argv, port, max_port);
97
98 for (; port <= max_port; port++) {
99 DMSG("rtt %u", rtt_4);
100
101 /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
102 set_nport(&lsap->u.sa, htons(port));
103 s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
104 /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
105 /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
106 ndelay_on(s);
107
108 DMSG("connect to port %u", port);
109 result_str = NULL;
110 start = MONOTONIC_US();
111 if (connect(s, &lsap->u.sa, lsap->len) == 0) {
112 /* Unlikely, for me even localhost fails :) */
113 DMSG("connect succeeded");
114 goto open;
115 }
116 /* Check for untypical errors... */
117 if (errno != EAGAIN && errno != EINPROGRESS
118 && errno != ECONNREFUSED
119 ) {
120 bb_perror_nomsg_and_die();
121 }
122
123 diff = 0;
124 while (1) {
125 if (errno == ECONNREFUSED) {
126 if (opt & 1) /* -c: show closed too */
127 result_str = "closed";
128 closed_ports++;
129 break;
130 }
131 DERR("port %u errno %d @%u", port, errno, diff);
132
133 if (diff > rtt_4) {
134 if (opt & 2) /* -b: show blocked too */
135 result_str = "blocked";
136 break;
137 }
138 /* Can sleep (much) longer than specified delay.
139 * We check rtt BEFORE we usleep, otherwise
140 * on localhost we'll have no writes done (!)
141 * before we exceed (rather small) rtt */
142 usleep(rtt_4 / 8);
143 open:
144 diff = MONOTONIC_US() - start;
145 DMSG("write to port %u @%u", port, diff - start);
146 if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
147 open_ports++;
148 result_str = "open";
149 break;
150 }
151 }
152 DMSG("out of loop @%u", diff);
153 if (result_str)
154 printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
155 port, result_str, port_name(port));
156
157 /* Estimate new rtt - we don't want to wait entire timeout
158 * for each port. *4 allows for rise in net delay.
159 * We increase rtt quickly (rtt_4*4), decrease slowly
160 * (diff is at least rtt_4/8, *4 == rtt_4/2)
161 * because we don't want to accidentally miss ports. */
162 rtt_4 = diff * 4;
163 if (rtt_4 < min_rtt)
164 rtt_4 = min_rtt;
165 if (rtt_4 > timeout)
166 rtt_4 = timeout;
167 /* Clean up */
168 close(s);
169 }
170 if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
171
172 printf("%u closed, %u open, %u timed out (or blocked) ports\n",
173 closed_ports,
174 open_ports,
175 nports - (closed_ports + open_ports));
176 return EXIT_SUCCESS;
177 }
178