lib/libwrap/percent_x.c

   1 /*      $NetBSD: percent_x.c,v 1.2 1997/10/09 21:20:41 christos Exp $   */
   2
   3  /*
   4   * percent_x() takes a string and performs %<char> expansions. It aborts the
   5   * program when the expansion would overflow the output buffer. The result
   6   * of %<char> expansion may be passed on to a shell process. For this
   7   * reason, characters with a special meaning to shells are replaced by
   8   * underscores.
   9   *
  10   * Diagnostics are reported through syslog(3).
  11   *
  12   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
  13   */
  14
  15 #include <sys/cdefs.h>
  16 #ifndef lint
  17 #if 0
  18 static char sccsid[] = "@(#) percent_x.c 1.4 94/12/28 17:42:37";
  19 #else
  20 __RCSID("$NetBSD: percent_x.c,v 1.2 1997/10/09 21:20:41 christos Exp $");
  21 #endif
  22 #endif
  23
  24 /* System libraries. */
  25
  26 #include <stdio.h>
  27 #include <syslog.h>
  28 #include <stdlib.h>
  29 #include <unistd.h>
  30 #include <string.h>
  31
  32 /* Local stuff. */
  33
  34 #include "tcpd.h"
  35
  36 /* percent_x - do %<char> expansion, abort if result buffer is too small */
  37
  38 char   *percent_x(result, result_len, string, request)
  39 char   *result;
  40 int     result_len;
  41 char   *string;
  42 struct request_info *request;
  43 {
  44     char   *bp = result;
  45     char   *end = result + result_len - 1;      /* end of result buffer */
  46     char   *expansion;
  47     int     expansion_len;
  48     static char ok_chars[] = "1234567890!@%-_=+:,./\
  49 abcdefghijklmnopqrstuvwxyz\
  50 ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  51     char   *str = string;
  52     char   *cp;
  53     int     ch;
  54
  55     /*
  56      * Warning: we may be called from a child process or after pattern
  57      * matching, so we cannot use clean_exit() or tcpd_jump().
  58      */
  59
  60     while (*str) {
  61         if (*str == '%' && (ch = str[1]) != 0) {
  62             str += 2;
  63             expansion =
  64                 ch == 'a' ? eval_hostaddr(request->client) :
  65                 ch == 'A' ? eval_hostaddr(request->server) :
  66                 ch == 'c' ? eval_client(request) :
  67                 ch == 'd' ? eval_daemon(request) :
  68                 ch == 'h' ? eval_hostinfo(request->client) :
  69                 ch == 'H' ? eval_hostinfo(request->server) :
  70                 ch == 'n' ? eval_hostname(request->client) :
  71                 ch == 'N' ? eval_hostname(request->server) :
  72                 ch == 'p' ? eval_pid(request) :
  73                 ch == 's' ? eval_server(request) :
  74                 ch == 'u' ? eval_user(request) :
  75                 ch == '%' ? "%" : (tcpd_warn("unrecognized %%%c", ch), "");
  76             for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ )
  77                 *cp = '_';
  78             expansion_len = cp - expansion;
  79         } else {
  80             expansion = str++;
  81             expansion_len = 1;
  82         }
  83         if (bp + expansion_len >= end) {
  84             tcpd_warn("percent_x: expansion too long: %.30s...", result);
  85             sleep(5);
  86             exit(0);
  87         }
  88         memcpy(bp, expansion, expansion_len);
  89         bp += expansion_len;
  90     }
  91     *bp = 0;
  92     return (result);
  93 }