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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* rfc931() speaks a common subset of the RFC 931, AUTH, TAP, IDENT and RFC
* 1413 protocols. It queries an RFC 931 etc. compatible daemon on a remote
* host to look up the owner of a connection. The information should not be
* used for authentication purposes. This routine intercepts alarm signals.
*
* Diagnostics are reported through syslog(3).
*
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
*/
/* System libraries. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <setjmp.h>
#include <signal.h>
#include <string.h>
/* Local stuff. */
#include "tcpd.h"
#define RFC931_PORT 113 /* Semi-well-known port */
#define ANY_PORT 0 /* Any old port will do */
int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */
static jmp_buf timebuf;
/* fsocket - open stdio stream on top of socket */
static FILE *fsocket(domain, type, protocol)
int domain;
int type;
int protocol;
{
int s;
FILE *fp;
if ((s = socket(domain, type, protocol)) < 0) {
tcpd_warn("socket: %m");
return (0);
} else {
if ((fp = fdopen(s, "r+")) == 0) {
tcpd_warn("fdopen: %m");
close(s);
}
return (fp);
}
}
/* timeout - handle timeouts */
static void timeout(sig)
int sig;
{
longjmp(timebuf, sig);
}
/* rfc931 - return remote user name, given socket structures */
void rfc931(rmt_sin, our_sin, dest)
struct sockaddr_gen *rmt_sin;
struct sockaddr_gen *our_sin;
char *dest;
{
unsigned rmt_port;
unsigned our_port;
struct sockaddr_gen rmt_query_sin;
struct sockaddr_gen our_query_sin;
char user[256]; /* XXX */
char buffer[512]; /* XXX */
char *cp;
char *volatile result = unknown;
FILE *fp;
volatile unsigned saved_timeout = 0;
struct sigaction nact, oact;
/*
* Use one unbuffered stdio stream for writing to and for reading from
* the RFC931 etc. server. This is done because of a bug in the SunOS
* 4.1.x stdio library. The bug may live in other stdio implementations,
* too. When we use a single, buffered, bidirectional stdio stream ("r+"
* or "w+" mode) we read our own output. Such behaviour would make sense
* with resources that support random-access operations, but not with
* sockets.
*/
if ((fp = fsocket(SGFAM(rmt_sin), SOCK_STREAM, 0)) != 0) {
setbuf(fp, NULL);
/*
* Set up a timer so we won't get stuck while waiting for the server.
*/
if (setjmp(timebuf) == 0) {
/*
* save the pending time in case the caller has armed an alarm.
*/
saved_timeout = alarm(0);
/*
* It's guaranteed to enter this 'if' condition on the direct
* invocation of setjmp and hence no additional checks while
* restoring the signal handler.
* Now, get the old handler and set the new one
*/
nact.sa_handler = timeout;
nact.sa_flags = 0;
(void) sigemptyset(&nact.sa_mask);
(void) sigaction(SIGALRM, &nact, &oact);
alarm(rfc931_timeout);
/*
* Bind the local and remote ends of the query socket to the same
* IP addresses as the connection under investigation. We go
* through all this trouble because the local or remote system
* might have more than one network address. The RFC931 etc.
* client sends only port numbers; the server takes the IP
* addresses from the query socket.
*/
our_query_sin = *our_sin;
SGPORT(&our_query_sin) = htons(ANY_PORT);
rmt_query_sin = *rmt_sin;
SGPORT(&rmt_query_sin) = htons(RFC931_PORT);
if (bind(fileno(fp), (struct sockaddr *) &our_query_sin,
SGSOCKADDRSZ(&our_query_sin)) >= 0 &&
connect(fileno(fp), (struct sockaddr *) &rmt_query_sin,
SGSOCKADDRSZ(&rmt_query_sin)) >= 0) {
/*
* Send query to server. Neglect the risk that a 13-byte
* write would have to be fragmented by the local system and
* cause trouble with buggy System V stdio libraries.
*/
fprintf(fp, "%u,%u\r\n",
ntohs(SGPORT(rmt_sin)),
ntohs(SGPORT(our_sin)));
fflush(fp);
/*
* Read response from server. Use fgets()/sscanf() so we can
* work around System V stdio libraries that incorrectly
* assume EOF when a read from a socket returns less than
* requested.
*/
if (fgets(buffer, sizeof(buffer), fp) != 0
&& ferror(fp) == 0 && feof(fp) == 0
&& sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
&rmt_port, &our_port, user) == 3
&& ntohs(SGPORT(rmt_sin)) == rmt_port
&& ntohs(SGPORT(our_sin)) == our_port) {
/*
* Strip trailing carriage return. It is part of the
* protocol, not part of the data.
*/
if (cp = strchr(user, '\r'))
*cp = 0;
result = user;
}
}
alarm(0);
}
/* Restore the old handler */
(void) sigaction(SIGALRM, &oact, NULL);
if (saved_timeout > 0)
alarm(saved_timeout);
fclose(fp);
}
STRN_CPY(dest, result, STRING_LENGTH);
}
|
