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 #include <unistd.h> 23 24 extern void exit(); 25 26 /* Local stuff. */ 27 28 #include "tcpd.h" 29 30 /* percent_x - do %<char> expansion, abort if result buffer is too small */ 31 32 char *percent_x(result, result_len, string, request) 33 char *result; 34 int result_len; 35 char *string; 36 struct request_info *request; 37 { 38 char *bp = result; 39 char *end = result + result_len - 1; /* end of result buffer */ 40 char *expansion; 41 int expansion_len; 42 static char ok_chars[] = "1234567890!@%-_=+:,./\ 43 abcdefghijklmnopqrstuvwxyz\ 44 ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 45 char *str = string; 46 char *cp; 47 int ch; 48 49 /* 50 * Warning: we may be called from a child process or after pattern 51 * matching, so we cannot use clean_exit() or tcpd_jump(). 52 */ 53 54 while (*str) { 55 if (*str == '%' && (ch = str[1]) != 0) { 56 str += 2; 57 expansion = 58 ch == 'a' ? eval_hostaddr(request->client) : 59 ch == 'A' ? eval_hostaddr(request->server) : 60 ch == 'c' ? eval_client(request) : 61 ch == 'd' ? eval_daemon(request) : 62 ch == 'h' ? eval_hostinfo(request->client) : 63 ch == 'H' ? eval_hostinfo(request->server) : 64 ch == 'n' ? eval_hostname(request->client) : 65 ch == 'N' ? eval_hostname(request->server) : 66 ch == 'p' ? eval_pid(request) : 67 ch == 's' ? eval_server(request) : 68 ch == 'u' ? eval_user(request) : 69 ch == '%' ? "%" : (tcpd_warn("unrecognized %%%c", ch), ""); 70 for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ ) 71 *cp = '_'; 72 expansion_len = cp - expansion; 73 } else { 74 expansion = str++; 75 expansion_len = 1; 76 } 77 if (bp + expansion_len >= end) { 78 tcpd_warn("percent_x: expansion too long: %.30s...", result); 79 sleep(5); 80 exit(0); 81 } 82 memcpy(bp, expansion, expansion_len); 83 bp += expansion_len; 84 } 85 *bp = 0; 86 return (result); 87 } 88