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percent_x.c revision 1.5 
      1 /*	$NetBSD: percent_x.c,v 1.5 2012/03/21 10:10:37 matt 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 1.5 2012/03/21 10:10:37 matt 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 *
     39 percent_x(char *result, int result_len, char *string,
     40     struct request_info *request)
     41 {
     42     char   *bp = result;
     43     char   *end = result + result_len - 1;	/* end of result buffer */
     44     char   *expansion;
     45     size_t  expansion_len;
     46     static const char ok_chars[] = "1234567890!@%-_=+:,./"
     47 	"abcdefghijklmnopqrstuvwxyz"
     48 	"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
     49     char   *str = string;
     50     char   *cp;
     51     int     ch;
     52 
     53     /*
     54      * Warning: we may be called from a child process or after pattern
     55      * matching, so we cannot use clean_exit() or tcpd_jump().
     56      */
     57 
     58     while (*str) {
     59 	if (*str == '%' && (ch = str[1]) != 0) {
     60 	    str += 2;
     61 	    expansion =
     62 		ch == 'a' ? eval_hostaddr(request->client) :
     63 		ch == 'A' ? eval_hostaddr(request->server) :
     64 		ch == 'c' ? eval_client(request) :
     65 		ch == 'd' ? eval_daemon(request) :
     66 		ch == 'h' ? eval_hostinfo(request->client) :
     67 		ch == 'H' ? eval_hostinfo(request->server) :
     68 		ch == 'n' ? eval_hostname(request->client) :
     69 		ch == 'N' ? eval_hostname(request->server) :
     70 		ch == 'p' ? eval_pid(request) :
     71 		ch == 's' ? eval_server(request) :
     72 		ch == 'u' ? eval_user(request) :
     73 		ch == '%' ? __UNCONST("%")
     74 		          : (tcpd_warn("unrecognized %%%c", ch), __UNCONST(""));
     75 	    for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ )
     76 		*cp = '_';
     77 	    expansion_len = cp - expansion;
     78 	} else {
     79 	    expansion = str++;
     80 	    expansion_len = 1;
     81 	}
     82 	if (bp + expansion_len >= end) {
     83 	    tcpd_warn("percent_x: expansion too long: %.30s...", result);
     84 	    sleep(5);
     85 	    exit(0);
     86 	}
     87 	memcpy(bp, expansion, expansion_len);
     88 	bp += expansion_len;
     89     }
     90     *bp = 0;
     91     return (result);
     92 }
     93