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 /* System libraries. */ 14 15 #include <stdio.h> 16 #include <syslog.h> 17 #include <string.h> 18 #include <unistd.h> 19 20 extern void exit(); 21 22 /* Local stuff. */ 23 24 #include "tcpd.h" 25 26 /* percent_x - do %<char> expansion, abort if result buffer is too small */ 27 28 char *percent_x(result, result_len, string, request) 29 char *result; 30 int result_len; 31 char *string; 32 struct request_info *request; 33 { 34 char *bp = result; 35 char *end = result + result_len - 1; /* end of result buffer */ 36 char *expansion; 37 int expansion_len; 38 static char ok_chars[] = "1234567890!@%-_=+:,./\ 39 abcdefghijklmnopqrstuvwxyz\ 40 ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 41 char *str = string; 42 char *cp; 43 int ch; 44 45 /* 46 * Warning: we may be called from a child process or after pattern 47 * matching, so we cannot use clean_exit() or tcpd_jump(). 48 */ 49 50 while (*str) { 51 if (*str == '%' && (ch = str[1]) != 0) { 52 str += 2; 53 expansion = 54 ch == 'a' ? eval_hostaddr(request->client) : 55 ch == 'A' ? eval_hostaddr(request->server) : 56 ch == 'c' ? eval_client(request) : 57 ch == 'd' ? eval_daemon(request) : 58 ch == 'h' ? eval_hostinfo(request->client) : 59 ch == 'H' ? eval_hostinfo(request->server) : 60 ch == 'n' ? eval_hostname(request->client) : 61 ch == 'N' ? eval_hostname(request->server) : 62 ch == 'p' ? eval_pid(request) : 63 ch == 's' ? eval_server(request) : 64 ch == 'u' ? eval_user(request) : 65 ch == '%' ? "%" : (tcpd_warn("unrecognized %%%c", ch), ""); 66 for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ ) 67 *cp = '_'; 68 expansion_len = cp - expansion; 69 } else { 70 expansion = str++; 71 expansion_len = 1; 72 } 73 if (bp + expansion_len >= end) { 74 tcpd_warn("percent_x: expansion too long: %.30s...", result); 75 sleep(5); 76 exit(0); 77 } 78 memcpy(bp, expansion, expansion_len); 79 bp += expansion_len; 80 } 81 *bp = 0; 82 return (result); 83 } 84