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