Home | History | Annotate | Line # | Download | only in libwrap 
      1 /*	$NetBSD: eval.c,v 1.7 2012/03/21 10:10:37 matt Exp $	*/
      2 
      3  /*
      4   * Routines for controlled evaluation of host names, user names, and so on.
      5   * They are, in fact, wrappers around the functions that are specific for
      6   * the sockets or TLI programming interfaces. The request_info and host_info
      7   * structures are used for result cacheing.
      8   *
      9   * These routines allows us to postpone expensive operations until their
     10   * results are really needed. Examples are hostname lookups and double
     11   * checks, or username lookups. Information that cannot be retrieved is
     12   * given the value "unknown" ("paranoid" in case of hostname problems).
     13   *
     14   * When ALWAYS_HOSTNAME is off, hostname lookup is done only when required by
     15   * tcpd paranoid mode, by access control patterns, or by %letter expansions.
     16   *
     17   * When ALWAYS_RFC931 mode is off, user lookup is done only when required by
     18   * access control patterns or %letter expansions.
     19   *
     20   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
     21   */
     22 
     23 #include <sys/cdefs.h>
     24 #ifndef lint
     25 #if 0
     26 static char sccsid[] = "@(#) eval.c 1.3 95/01/30 19:51:45";
     27 #else
     28 __RCSID("$NetBSD: eval.c,v 1.7 2012/03/21 10:10:37 matt Exp $");
     29 #endif
     30 #endif
     31 
     32 /* System libraries. */
     33 
     34 #include <stdio.h>
     35 #include <string.h>
     36 
     37 /* Local stuff. */
     38 
     39 #include "tcpd.h"
     40 
     41  /*
     42   * When a string has the value STRING_UNKNOWN, it means: don't bother, I
     43   * tried to look up the data but it was unavailable for some reason. When a
     44   * host name has the value STRING_PARANOID it means there was a name/address
     45   * conflict.
     46   */
     47 char    unknown[] = STRING_UNKNOWN;
     48 char    paranoid[] = STRING_PARANOID;
     49 
     50 /* eval_user - look up user name */
     51 
     52 char   *
     53 eval_user(struct request_info *request)
     54 {
     55     if (request->user[0] == 0) {
     56 	(void)strlcpy(request->user, unknown, sizeof(request->user));
     57 	if (request->sink == 0 && request->client->sin && request->server->sin)
     58 	    rfc931(request->client->sin, request->server->sin, request->user);
     59     }
     60     return (request->user);
     61 }
     62 
     63 /* eval_hostaddr - look up printable address */
     64 
     65 char   *
     66 eval_hostaddr(struct host_info *host)
     67 {
     68     if (host->addr[0] == 0) {
     69 	(void)strlcpy(host->addr, unknown, sizeof(host->addr));
     70 	if (host->request->hostaddr != 0)
     71 	    host->request->hostaddr(host);
     72     }
     73     return (host->addr);
     74 }
     75 
     76 /* eval_hostname - look up host name */
     77 
     78 char   *
     79 eval_hostname(struct host_info *host)
     80 {
     81     if (host->name[0] == 0) {
     82 	(void)strlcpy(host->name, unknown, sizeof(host->name));
     83 	if (host->request->hostname != 0)
     84 	    host->request->hostname(host);
     85     }
     86     return (host->name);
     87 }
     88 
     89 /* eval_hostinfo - return string with host name (preferred) or address */
     90 
     91 char   *
     92 eval_hostinfo(struct host_info *host)
     93 {
     94     char   *hostname;
     95 
     96 #ifndef ALWAYS_HOSTNAME				/* no implicit host lookups */
     97     if (host->name[0] == 0)
     98 	return (eval_hostaddr(host));
     99 #endif
    100     hostname = eval_hostname(host);
    101     if (HOSTNAME_KNOWN(hostname)) {
    102 	return (host->name);
    103     } else {
    104 	return (eval_hostaddr(host));
    105     }
    106 }
    107 
    108 /* eval_client - return string with as much about the client as we know */
    109 
    110 char   *
    111 eval_client(struct request_info *request)
    112 {
    113     static char both[2 * STRING_LENGTH];
    114     char   *hostinfo = eval_hostinfo(request->client);
    115 
    116 #ifndef ALWAYS_RFC931				/* no implicit user lookups */
    117     if (request->user[0] == 0)
    118 	return (hostinfo);
    119 #endif
    120     if (STR_NE(eval_user(request), unknown)) {
    121 	(void)snprintf(both, sizeof both, "%s@%s", request->user, hostinfo);
    122 	return (both);
    123     } else {
    124 	return (hostinfo);
    125     }
    126 }
    127 
    128 /* eval_server - return string with as much about the server as we know */
    129 
    130 char   *
    131 eval_server(struct request_info *request)
    132 {
    133     static char both[2 * STRING_LENGTH];
    134     char   *host = eval_hostinfo(request->server);
    135     char   *daemon = eval_daemon(request);
    136 
    137     if (STR_NE(host, unknown)) {
    138 	(void)snprintf(both, sizeof both, "%s@%s", daemon, host);
    139 	return (both);
    140     } else {
    141 	return (daemon);
    142     }
    143 }
    144