usr/src/lib/libwrap/eval.c

   1 /*
   2  * Copyright 2001 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5 #pragma ident   "%Z%%M% %I%     %E% SMI"
   6
   7  /*
   8   * Routines for controlled evaluation of host names, user names, and so on.
   9   * They are, in fact, wrappers around the functions that are specific for
  10   * the sockets or TLI programming interfaces. The request_info and host_info
  11   * structures are used for result cacheing.
  12   *
  13   * These routines allows us to postpone expensive operations until their
  14   * results are really needed. Examples are hostname lookups and double
  15   * checks, or username lookups. Information that cannot be retrieved is
  16   * given the value "unknown" ("paranoid" in case of hostname problems).
  17   *
  18   * When ALWAYS_HOSTNAME is off, hostname lookup is done only when required by
  19   * tcpd paranoid mode, by access control patterns, or by %letter expansions.
  20   *
  21   * When ALWAYS_RFC931 mode is off, user lookup is done only when required by
  22   * access control patterns or %letter expansions.
  23   *
  24   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
  25   */
  26
  27 static char sccsid[] = "@(#) eval.c 1.3 95/01/30 19:51:45";
  28
  29 /* System libraries. */
  30
  31 #include <stdio.h>
  32 #include <string.h>
  33
  34 /* Local stuff. */
  35
  36 #include "tcpd.h"
  37
  38  /*
  39   * When a string has the value STRING_UNKNOWN, it means: don't bother, I
  40   * tried to look up the data but it was unavailable for some reason. When a
  41   * host name has the value STRING_PARANOID it means there was a name/address
  42   * conflict.
  43   */
  44 char    unknown[] = STRING_UNKNOWN;
  45 char    paranoid[] = STRING_PARANOID;
  46
  47 /* eval_user - look up user name */
  48
  49 char   *eval_user(request)
  50 struct request_info *request;
  51 {
  52     if (request->user[0] == 0) {
  53         strcpy(request->user, unknown);
  54         if (request->sink == 0 && request->client->sin && request->server->sin)
  55             rfc931(request->client->sin, request->server->sin, request->user);
  56     }
  57     return (request->user);
  58 }
  59
  60 /* eval_hostaddr - look up printable address */
  61
  62 char   *eval_hostaddr(host)
  63 struct host_info *host;
  64 {
  65     if (host->addr[0] == 0) {
  66         strcpy(host->addr, unknown);
  67         if (host->request->hostaddr != 0)
  68             host->request->hostaddr(host);
  69     }
  70     return (host->addr);
  71 }
  72
  73 /* eval_hostname - look up host name */
  74
  75 char   *eval_hostname(host)
  76 struct host_info *host;
  77 {
  78     if (host->name[0] == 0) {
  79         strcpy(host->name, unknown);
  80         if (host->request->hostname != 0)
  81             host->request->hostname(host);
  82     }
  83     return (host->name);
  84 }
  85
  86 /* eval_hostinfo - return string with host name (preferred) or address */
  87
  88 char   *eval_hostinfo(host)
  89 struct host_info *host;
  90 {
  91     char   *hostname;
  92
  93 #ifndef ALWAYS_HOSTNAME                         /* no implicit host lookups */
  94     if (host->name[0] == 0)
  95         return (eval_hostaddr(host));
  96 #endif
  97     hostname = eval_hostname(host);
  98     if (HOSTNAME_KNOWN(hostname)) {
  99         return (host->name);
 100     } else {
 101         return (eval_hostaddr(host));
 102     }
 103 }
 104
 105 /* eval_client - return string with as much about the client as we know */
 106
 107 char   *eval_client(request)
 108 struct request_info *request;
 109 {
 110     static char both[2 * STRING_LENGTH];
 111     char   *hostinfo = eval_hostinfo(request->client);
 112
 113 #ifndef ALWAYS_RFC931                           /* no implicit user lookups */
 114     if (request->user[0] == 0)
 115         return (hostinfo);
 116 #endif
 117     if (STR_NE(eval_user(request), unknown)) {
 118         sprintf(both, "%s@%s", request->user, hostinfo);
 119         return (both);
 120     } else {
 121         return (hostinfo);
 122     }
 123 }
 124
 125 /* eval_server - return string with as much about the server as we know */
 126
 127 char   *eval_server(request)
 128 struct request_info *request;
 129 {
 130     static char both[2 * STRING_LENGTH];
 131     char   *host = eval_hostinfo(request->server);
 132     char   *daemon = eval_daemon(request);
 133
 134     if (STR_NE(host, unknown)) {
 135         sprintf(both, "%s@%s", daemon, host);
 136         return (both);
 137     } else {
 138         return (daemon);
 139     }
 140 }