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
|
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
extern int getopt(int, char *const*, const char *);
extern int optind;
extern char *optarg;
char * progname = "getpeername";
int numeric_addresses = 0;
char * protocol = NULL;
int sockno = 0;
void
usage(void)
{
fprintf(stderr, "Usage: %s [-n] [-p protocol]\n", progname);
exit(1);
}
void
fatal(char * msg)
{
fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(errno));
exit(1);
}
int
main(int argc,
char **argv)
{
int option;
struct sockaddr_in peer;
int peersize = sizeof peer;
char * hostname;
char * portname;
char servbuf[64];
progname = argv[0];
while ((option = getopt(argc, argv, "np:")) != EOF)
{
switch ((char)option)
{
case 'n':
numeric_addresses = 1;
break;
case 'p':
protocol = optarg;
break;
default:
usage();
/* NOTREACHED */
}
}
if (argc - optind > 0)
usage();
if (getpeername(sockno, (struct sockaddr*)&peer, &peersize) < 0)
fatal("can't get peer name");
if (peer.sin_family != AF_INET)
fatal("socket is not an IP socket");
/* Find the type of the socket. Assumes that an INET stream socket
* is TCP and an INET datagram socket is UDP. Can't handle AF_UNIX
* or any other adress families.
*/
if (protocol == NULL)
{
int socktype;
int socktypelen = sizeof socktype;
if (getsockopt(sockno, SOL_SOCKET, SO_TYPE,
(char*)&socktype, &socktypelen) < 0)
fatal("can't get socket type");
switch (socktype)
{
case SOCK_STREAM:
protocol = "tcp";
break;
case SOCK_DGRAM:
protocol = "udp";
break;
default:
fatal("unknown socket type");
/* NOTREACHED */
}
}
hostname = inet_ntoa(peer.sin_addr);
sprintf(servbuf, "%u", ntohs(peer.sin_port));
portname = servbuf;
if (!numeric_addresses)
{
struct hostent *host;
struct servent *service;
host = gethostbyaddr((char*)&peer.sin_addr.s_addr,
sizeof peer.sin_addr.s_addr, AF_INET);
if (host != NULL)
hostname = host->h_name;
service = getservbyport(peer.sin_port, protocol);
if (service != NULL)
portname = service->s_name;
}
printf("%s %s\n", hostname, portname);
return 0;
}
|
