1 /*
2  * Routines for controlled evaluation of host names, user names, and so on.
3  * They are, in fact, wrappers around the functions that are specific for
4  * the sockets or TLI programming interfaces. The request_info and host_info
5  * structures are used for result cacheing.
6  *
7  * These routines allows us to postpone expensive operations until their
8  * results are really needed. Examples are hostname lookups and double
9  * checks, or username lookups. Information that cannot be retrieved is
10  * given the value "unknown" ("paranoid" in case of hostname problems).
11  *
12  * When ALWAYS_HOSTNAME is off, hostname lookup is done only when required by
13  * tcpd paranoid mode, by access control patterns, or by %letter expansions.
14  *
15  * When ALWAYS_RFC931 mode is off, user lookup is done only when required by
16  * access control patterns or %letter expansions.
17  *
18  * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
19  */
20
21#ifndef lint
22static char sccsid[] = "@(#) eval.c 1.3 95/01/30 19:51:45";
23#endif
24
25/* System libraries. */
26
27#include <stdio.h>
28#include <string.h>
29
30/* Local stuff. */
31
32#include "tcpd.h"
33
34 /*
35  * When a string has the value STRING_UNKNOWN, it means: don't bother, I
36  * tried to look up the data but it was unavailable for some reason. When a
37  * host name has the value STRING_PARANOID it means there was a name/address
38  * conflict.
39  */
40char    unknown[] = STRING_UNKNOWN;
41char    paranoid[] = STRING_PARANOID;
42
43/* eval_user - look up user name */
44
45char   *eval_user(struct request_info *request)
46{
47    if (request->user[0] == 0) {
48	strcpy(request->user, unknown);
49	if (request->sink == 0 && request->client->sin && request->server->sin)
50	    rfc931(request->client->sin, request->server->sin, request->user);
51    }
52    return (request->user);
53}
54
55/* eval_hostaddr - look up printable address */
56
57char   *eval_hostaddr(struct host_info *host)
58{
59    if (host->addr[0] == 0) {
60	strcpy(host->addr, unknown);
61	if (host->request->hostaddr != 0)
62	    host->request->hostaddr(host);
63    }
64    return (host->addr);
65}
66
67/* eval_hostname - look up host name */
68
69char   *eval_hostname(struct host_info *host)
70{
71    if (host->name[0] == 0) {
72	strcpy(host->name, unknown);
73	if (host->request->hostname != 0)
74	    host->request->hostname(host);
75    }
76    return (host->name);
77}
78
79/* eval_hostinfo - return string with host name (preferred) or address */
80
81char   *eval_hostinfo(struct host_info *host)
82{
83    char   *hostname;
84
85#ifndef ALWAYS_HOSTNAME				/* no implicit host lookups */
86    if (host->name[0] == 0)
87	return (eval_hostaddr(host));
88#endif
89    hostname = eval_hostname(host);
90    if (HOSTNAME_KNOWN(hostname)) {
91	return (host->name);
92    } else {
93	return (eval_hostaddr(host));
94    }
95}
96
97/* eval_client - return string with as much about the client as we know */
98
99char   *eval_client(struct request_info *request)
100{
101    static char both[2 * STRING_LENGTH];
102    char   *hostinfo = eval_hostinfo(request->client);
103
104#ifndef ALWAYS_RFC931				/* no implicit user lookups */
105    if (request->user[0] == 0)
106	return (hostinfo);
107#endif
108    if (STR_NE(eval_user(request), unknown)) {
109	sprintf(both, "%s@%s", request->user, hostinfo);
110	return (both);
111    } else {
112	return (hostinfo);
113    }
114}
115
116/* eval_server - return string with as much about the server as we know */
117
118char   *eval_server(struct request_info *request)
119{
120    static char both[2 * STRING_LENGTH];
121    char   *host = eval_hostinfo(request->server);
122    char   *daemon = eval_daemon(request);
123
124    if (STR_NE(host, unknown)) {
125	sprintf(both, "%s@%s", daemon, host);
126	return (both);
127    } else {
128	return (daemon);
129    }
130}
131