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percent_x.c revision 1.2 
      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 }
     94