/*      $NetBSD: eval.c,v 1.7 2012/03/21 10:10:37 matt Exp $    */

/*
 * Routines for controlled evaluation of host names, user names, and so on.
 * They are, in fact, wrappers around the functions that are specific for
 * the sockets or TLI programming interfaces. The request_info and host_info
 * structures are used for result cacheing.
 *
 * These routines allows us to postpone expensive operations until their
 * results are really needed. Examples are hostname lookups and double
 * checks, or username lookups. Information that cannot be retrieved is
 * given the value "unknown" ("paranoid" in case of hostname problems).
 *
 * When ALWAYS_HOSTNAME is off, hostname lookup is done only when required by
 * tcpd paranoid mode, by access control patterns, or by %letter expansions.
 *
 * When ALWAYS_RFC931 mode is off, user lookup is done only when required by
 * access control patterns or %letter expansions.
 *
 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#) eval.c 1.3 95/01/30 19:51:45";
#else
__RCSID("$NetBSD: eval.c,v 1.7 2012/03/21 10:10:37 matt Exp $");
#endif
#endif

/* System libraries. */

#include <stdio.h>
#include <string.h>

/* Local stuff. */

#include "tcpd.h"

/*
 * When a string has the value STRING_UNKNOWN, it means: don't bother, I
 * tried to look up the data but it was unavailable for some reason. When a
 * host name has the value STRING_PARANOID it means there was a name/address
 * conflict.
 */
char    unknown[] = STRING_UNKNOWN;
char    paranoid[] = STRING_PARANOID;

/* eval_user - look up user name */

char   *
eval_user(struct request_info *request)
{
   if (request->user[0] == 0) {
       (void)strlcpy(request->user, unknown, sizeof(request->user));
       if (request->sink == 0 && request->client->sin && request->server->sin)
           rfc931(request->client->sin, request->server->sin, request->user);
   }
   return (request->user);
}

/* eval_hostaddr - look up printable address */

char   *
eval_hostaddr(struct host_info *host)
{
   if (host->addr[0] == 0) {
       (void)strlcpy(host->addr, unknown, sizeof(host->addr));
       if (host->request->hostaddr != 0)
           host->request->hostaddr(host);
   }
   return (host->addr);
}

/* eval_hostname - look up host name */

char   *
eval_hostname(struct host_info *host)
{
   if (host->name[0] == 0) {
       (void)strlcpy(host->name, unknown, sizeof(host->name));
       if (host->request->hostname != 0)
           host->request->hostname(host);
   }
   return (host->name);
}

/* eval_hostinfo - return string with host name (preferred) or address */

char   *
eval_hostinfo(struct host_info *host)
{
   char   *hostname;

#ifndef ALWAYS_HOSTNAME                         /* no implicit host lookups */
   if (host->name[0] == 0)
       return (eval_hostaddr(host));
#endif
   hostname = eval_hostname(host);
   if (HOSTNAME_KNOWN(hostname)) {
       return (host->name);
   } else {
       return (eval_hostaddr(host));
   }
}

/* eval_client - return string with as much about the client as we know */

char   *
eval_client(struct request_info *request)
{
   static char both[2 * STRING_LENGTH];
   char   *hostinfo = eval_hostinfo(request->client);

#ifndef ALWAYS_RFC931                           /* no implicit user lookups */
   if (request->user[0] == 0)
       return (hostinfo);
#endif
   if (STR_NE(eval_user(request), unknown)) {
       (void)snprintf(both, sizeof both, "%s@%s", request->user, hostinfo);
       return (both);
   } else {
       return (hostinfo);
   }
}

/* eval_server - return string with as much about the server as we know */

char   *
eval_server(struct request_info *request)
{
   static char both[2 * STRING_LENGTH];
   char   *host = eval_hostinfo(request->server);
   char   *daemon = eval_daemon(request);

   if (STR_NE(host, unknown)) {
       (void)snprintf(both, sizeof both, "%s@%s", daemon, host);
       return (both);
   } else {
       return (daemon);
   }
}