1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
/*
* Pscan is a mini port scanner implementation for busybox
*
* Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include "libbb.h"
/* debugging */
#ifdef DEBUG_PSCAN
#define DMSG(...) bb_error_msg(__VA_ARGS__)
#define DERR(...) bb_perror_msg(__VA_ARGS__)
#else
#define DMSG(...) ((void)0)
#define DERR(...) ((void)0)
#endif
static const char *port_name(unsigned port)
{
struct servent *server;
server = getservbyport(htons(port), NULL);
if (server)
return server->s_name;
return "unknown";
}
/* We don't expect to see 1000+ seconds delay, unsigned is enough */
#define MONOTONIC_US() ((unsigned)monotonic_us())
int pscan_main(int argc, char **argv);
int pscan_main(int argc, char **argv)
{
const char *opt_max_port = "1024"; /* -P: default max port */
const char *opt_min_port = "1"; /* -p: default min port */
const char *opt_timeout = "5000"; /* -t: default timeout in msec */
/* We estimate rtt and wait rtt*4 before concluding that port is
* totally blocked. min rtt of 5 ms may be too low if you are
* scanning an Internet host behind saturated/traffic shaped link.
* Rule of thumb: with min_rtt of N msec, scanning 1000 ports
* will take N seconds at absolute minimum */
const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
len_and_sockaddr *lsap;
int s;
unsigned port, max_port, nports;
unsigned closed_ports = 0;
unsigned open_ports = 0;
/* all in usec */
unsigned timeout;
unsigned min_rtt;
unsigned rtt_4;
unsigned start;
opt_complementary = "=1"; /* exactly one non-option */
getopt32(argc, argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
argv += optind;
max_port = xatou_range(opt_max_port, 1, 65535);
port = xatou_range(opt_min_port, 1, max_port);
nports = max_port - port + 1;
rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
DMSG("min_rtt %u timeout %u", min_rtt, timeout);
lsap = xhost2sockaddr(*argv, port);
printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
*argv, port, max_port);
for (; port <= max_port; port++) {
DMSG("rtt %u", rtt_4);
/* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
set_nport(lsap, htons(port));
s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
/* We need unblocking socket so we don't need to wait for ETIMEOUT. */
/* Nonblocking connect typically "fails" with errno == EINPROGRESS */
ndelay_on(s);
DMSG("connect to port %u", port);
start = MONOTONIC_US();
if (connect(s, &lsap->sa, lsap->len) == 0) {
/* Unlikely, for me even localhost fails :) */
DMSG("connect succeeded");
goto open;
}
/* Check for untypical errors... */
if (errno != EAGAIN && errno != EINPROGRESS
&& errno != ECONNREFUSED
) {
bb_perror_nomsg_and_die();
}
while (1) {
if (errno == ECONNREFUSED) {
DMSG("port %u: ECONNREFUSED", port);
closed_ports++;
break;
}
DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
if ((MONOTONIC_US() - start) > rtt_4)
break;
/* Can sleep (much) longer than specified delay.
* We check rtt BEFORE we usleep, otherwise
* on localhost we'll do zero writes done (!)
* before we exceed (rather small) rtt */
usleep(rtt_4/8);
DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
open:
open_ports++;
printf("%5u\ttcp\topen\t%s\n", port, port_name(port));
break;
}
}
DMSG("out of loop @%u", MONOTONIC_US() - start);
/* Estimate new rtt - we don't want to wait entire timeout
* for each port. *4 allows for rise in net delay.
* We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
* because we don't want to accidentally miss ports. */
rtt_4 = (MONOTONIC_US() - start) * 4;
if (rtt_4 < min_rtt)
rtt_4 = min_rtt;
if (rtt_4 > timeout)
rtt_4 = timeout;
/* Clean up */
close(s);
}
if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
printf("%d closed, %d open, %d timed out ports\n",
closed_ports,
open_ports,
nports - (closed_ports + open_ports));
return EXIT_SUCCESS;
}
|
