contrib/tcp_wrappers/eval.c

   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
  45 char   *eval_user(request)
  46 struct request_info *request;
  47 {
  48     if (request->user[0] == 0) {
  49         strcpy(request->user, unknown);
  50         if (request->sink == 0 && request->client->sin && request->server->sin)
  51             rfc931(request->client->sin, request->server->sin, request->user);
  52     }
  53     return (request->user);
  54 }
  55
  56 /* eval_hostaddr - look up printable address */
  57
  58 char   *eval_hostaddr(host)
  59 struct host_info *host;
  60 {
  61     if (host->addr[0] == 0) {
  62         strcpy(host->addr, unknown);
  63         if (host->request->hostaddr != 0)
  64             host->request->hostaddr(host);
  65     }
  66     return (host->addr);
  67 }
  68
  69 /* eval_hostname - look up host name */
  70
  71 char   *eval_hostname(host)
  72 struct host_info *host;
  73 {
  74     if (host->name[0] == 0) {
  75         strcpy(host->name, unknown);
  76         if (host->request->hostname != 0)
  77             host->request->hostname(host);
  78     }
  79     return (host->name);
  80 }
  81
  82 /* eval_hostinfo - return string with host name (preferred) or address */
  83
  84 char   *eval_hostinfo(host)
  85 struct host_info *host;
  86 {
  87     char   *hostname;
  88
  89 #ifndef ALWAYS_HOSTNAME                         /* no implicit host lookups */
  90     if (host->name[0] == 0)
  91         return (eval_hostaddr(host));
  92 #endif
  93     hostname = eval_hostname(host);
  94     if (HOSTNAME_KNOWN(hostname)) {
  95         return (host->name);
  96     } else {
  97         return (eval_hostaddr(host));
  98     }
  99 }
 100
 101 /* eval_client - return string with as much about the client as we know */
 102
 103 char   *eval_client(request)
 104 struct request_info *request;
 105 {
 106     static char both[2 * STRING_LENGTH];
 107     char   *hostinfo = eval_hostinfo(request->client);
 108
 109 #ifndef ALWAYS_RFC931                           /* no implicit user lookups */
 110     if (request->user[0] == 0)
 111         return (hostinfo);
 112 #endif
 113     if (STR_NE(eval_user(request), unknown)) {
 114         sprintf(both, "%s@%s", request->user, hostinfo);
 115         return (both);
 116     } else {
 117         return (hostinfo);
 118     }
 119 }
 120
 121 /* eval_server - return string with as much about the server as we know */
 122
 123 char   *eval_server(request)
 124 struct request_info *request;
 125 {
 126     static char both[2 * STRING_LENGTH];
 127     char   *host = eval_hostinfo(request->server);
 128     char   *daemon = eval_daemon(request);
 129
 130     if (STR_NE(host, unknown)) {
 131         sprintf(both, "%s@%s", daemon, host);
 132         return (both);
 133     } else {
 134         return (daemon);
 135     }
 136 }