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
22 static 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 */
40 char unknown[] = STRING_UNKNOWN;
41 char paranoid[] = STRING_PARANOID;
42
43 /* eval_user - look up user name */
44
eval_user(struct request_info * request)45 char *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
eval_hostaddr(struct host_info * host)57 char *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
eval_hostname(struct host_info * host)69 char *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
eval_hostinfo(struct host_info * host)81 char *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
eval_client(struct request_info * request)99 char *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
eval_server(struct request_info * request)118 char *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