/* * percent_x() takes a string and performs %<char> expansions. It aborts the * program when the expansion would overflow the output buffer. The result * of %<char> expansion may be passed on to a shell process. For this * reason, characters with a special meaning to shells are replaced by * underscores. * * Diagnostics are reported through syslog(3). * * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. */ #ifndef lint static char sccsid[] = "@(#) percent_x.c 1.4 94/12/28 17:42:37"; #endif /* System libraries. */ #include <stdio.h> #include <syslog.h> #include <string.h> #include <unistd.h> extern void exit(); /* Local stuff. */ #include "tcpd.h" /* percent_x - do %<char> expansion, abort if result buffer is too small */ char *percent_x(result, result_len, string, request) char *result; int result_len; char *string; struct request_info *request; { char *bp = result; char *end = result + result_len - 1; /* end of result buffer */ char *expansion; int expansion_len; static char ok_chars[] = "1234567890!@%-_=+:,./\ abcdefghijklmnopqrstuvwxyz\ ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char *str = string; char *cp; int ch; /* * Warning: we may be called from a child process or after pattern * matching, so we cannot use clean_exit() or tcpd_jump(). */ while (*str) { if (*str == '%' && (ch = str[1]) != 0) { str += 2; expansion = ch == 'a' ? eval_hostaddr(request->client) : ch == 'A' ? eval_hostaddr(request->server) : ch == 'c' ? eval_client(request) : ch == 'd' ? eval_daemon(request) : ch == 'h' ? eval_hostinfo(request->client) : ch == 'H' ? eval_hostinfo(request->server) : ch == 'n' ? eval_hostname(request->client) : ch == 'N' ? eval_hostname(request->server) : ch == 'p' ? eval_pid(request) : ch == 's' ? eval_server(request) : ch == 'u' ? eval_user(request) : ch == '%' ? "%" : (tcpd_warn("unrecognized %%%c", ch), ""); for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ ) *cp = '_'; expansion_len = cp - expansion; } else { expansion = str++; expansion_len = 1; } if (bp + expansion_len >= end) { tcpd_warn("percent_x: expansion too long: %.30s...", result); sleep(5); exit(0); } memcpy(bp, expansion, expansion_len); bp += expansion_len; } *bp = 0; return (result); } |