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 #ifndef lint
  28 static char sccsid[] = "@(#) eval.c 1.3 95/01/30 19:51:45";
  29 #endif
  30
  31 /* System libraries. */
  32
  33 #include <stdio.h>
  34 #include <string.h>
  35
  36 /* Local stuff. */
  37
  38 #include "tcpd.h"
  39
  40  /*
  41   * When a string has the value STRING_UNKNOWN, it means: don't bother, I
  42   * tried to look up the data but it was unavailable for some reason. When a
  43   * host name has the value STRING_PARANOID it means there was a name/address
  44   * conflict.
  45   */
  46 char    unknown[] = STRING_UNKNOWN;
  47 char    paranoid[] = STRING_PARANOID;
  48
  49 /* eval_user - look up user name */
  50
  51 char   *eval_user(request)
  52 struct request_info *request;
  53 {
  54     if (request->user[0] == 0) {
  55         strcpy(request->user, unknown);
  56         if (request->sink == 0 && request->client->sin && request->server->sin)
  57             rfc931(request->client->sin, request->server->sin, request->user);
  58     }
  59     return (request->user);
  60 }
  61
  62 /* eval_hostaddr - look up printable address */
  63
  64 char   *eval_hostaddr(host)
  65 struct host_info *host;
  66 {
  67     if (host->addr[0] == 0) {
  68         strcpy(host->addr, unknown);
  69         if (host->request->hostaddr != 0)
  70             host->request->hostaddr(host);
  71     }
  72     return (host->addr);
  73 }
  74
  75 /* eval_hostname - look up host name */
  76
  77 char   *eval_hostname(host)
  78 struct host_info *host;
  79 {
  80     if (host->name[0] == 0) {
  81         strcpy(host->name, unknown);
  82         if (host->request->hostname != 0)
  83             host->request->hostname(host);
  84     }
  85     return (host->name);
  86 }
  87
  88 /* eval_hostinfo - return string with host name (preferred) or address */
  89
  90 char   *eval_hostinfo(host)
  91 struct host_info *host;
  92 {
  93     char   *hostname;
  94
  95 #ifndef ALWAYS_HOSTNAME                         /* no implicit host lookups */
  96     if (host->name[0] == 0)
  97         return (eval_hostaddr(host));
  98 #endif
  99     hostname = eval_hostname(host);
 100     if (HOSTNAME_KNOWN(hostname)) {
 101         return (host->name);
 102     } else {
 103         return (eval_hostaddr(host));
 104     }
 105 }
 106
 107 /* eval_client - return string with as much about the client as we know */
 108
 109 char   *eval_client(request)
 110 struct request_info *request;
 111 {
 112     static char both[2 * STRING_LENGTH];
 113     char   *hostinfo = eval_hostinfo(request->client);
 114
 115 #ifndef ALWAYS_RFC931                           /* no implicit user lookups */
 116     if (request->user[0] == 0)
 117         return (hostinfo);
 118 #endif
 119     if (STR_NE(eval_user(request), unknown)) {
 120         sprintf(both, "%s@%s", request->user, hostinfo);
 121         return (both);
 122     } else {
 123         return (hostinfo);
 124     }
 125 }
 126
 127 /* eval_server - return string with as much about the server as we know */
 128
 129 char   *eval_server(request)
 130 struct request_info *request;
 131 {
 132     static char both[2 * STRING_LENGTH];
 133     char   *host = eval_hostinfo(request->server);
 134     char   *daemon = eval_daemon(request);
 135
 136     if (STR_NE(host, unknown)) {
 137         sprintf(both, "%s@%s", daemon, host);
 138         return (both);
 139     } else {
 140         return (daemon);
 141     }
 142 }