lib/libwrap/eval.c

   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 }