622 lines
15 KiB
C
622 lines
15 KiB
C
/*
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* General skeleton for adding options to the access control language. The
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* features offered by this module are documented in the hosts_options(5)
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* manual page (source file: hosts_options.5, "nroff -man" format).
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*
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* Notes and warnings for those who want to add features:
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*
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* In case of errors, abort options processing and deny access. There are too
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* many irreversible side effects to make error recovery feasible. For
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* example, it makes no sense to continue after we have already changed the
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* userid.
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*
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* In case of errors, do not terminate the process: the routines might be
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* called from a long-running daemon that should run forever. Instead, call
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* tcpd_jump() which does a non-local goto back into the hosts_access()
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* routine.
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*
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* In case of severe errors, use clean_exit() instead of directly calling
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* exit(), or the inetd may loop on an UDP request.
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*
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* In verification mode (for example, with the "tcpdmatch" command) the
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* "dry_run" flag is set. In this mode, an option function should just "say"
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* what it is going to do instead of really doing it.
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*
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* Some option functions do not return (for example, the twist option passes
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* control to another program). In verification mode (dry_run flag is set)
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* such options should clear the "dry_run" flag to inform the caller of this
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* course of action.
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*/
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#ifndef lint
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static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
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#endif
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/* System libraries. */
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <syslog.h>
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#include <pwd.h>
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#include <grp.h>
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#include <ctype.h>
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#include <setjmp.h>
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#include <string.h>
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#ifndef MAXPATHNAMELEN
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#define MAXPATHNAMELEN BUFSIZ
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#endif
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/* Local stuff. */
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#include "tcpd.h"
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/* Options runtime support. */
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int dry_run = 0; /* flag set in verification mode */
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extern jmp_buf tcpd_buf; /* tcpd_jump() support */
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/* Options parser support. */
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static char whitespace_eq[] = "= \t\r\n";
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#define whitespace (whitespace_eq + 1)
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static char *get_field(); /* chew :-delimited field off string */
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static char *chop_string(); /* strip leading and trailing blanks */
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/* List of functions that implement the options. Add yours here. */
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static void user_option(); /* execute "user name.group" option */
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static void group_option(); /* execute "group name" option */
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static void umask_option(); /* execute "umask mask" option */
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static void linger_option(); /* execute "linger time" option */
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static void keepalive_option(); /* execute "keepalive" option */
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static void spawn_option(); /* execute "spawn command" option */
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static void twist_option(); /* execute "twist command" option */
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static void rfc931_option(); /* execute "rfc931" option */
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static void setenv_option(); /* execute "setenv name value" */
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static void nice_option(); /* execute "nice" option */
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static void severity_option(); /* execute "severity value" */
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static void allow_option(); /* execute "allow" option */
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static void deny_option(); /* execute "deny" option */
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static void banners_option(); /* execute "banners path" option */
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/* Structure of the options table. */
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struct option {
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char *name; /* keyword name, case is ignored */
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void (*func) (); /* function that does the real work */
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int flags; /* see below... */
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};
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#define NEED_ARG (1<<1) /* option requires argument */
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#define USE_LAST (1<<2) /* option must be last */
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#define OPT_ARG (1<<3) /* option has optional argument */
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#define EXPAND_ARG (1<<4) /* do %x expansion on argument */
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#define need_arg(o) ((o)->flags & NEED_ARG)
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#define opt_arg(o) ((o)->flags & OPT_ARG)
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#define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG))
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#define use_last(o) ((o)->flags & USE_LAST)
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#define expand_arg(o) ((o)->flags & EXPAND_ARG)
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/* List of known keywords. Add yours here. */
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static struct option option_table[] = {
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"user", user_option, NEED_ARG,
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"group", group_option, NEED_ARG,
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"umask", umask_option, NEED_ARG,
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"linger", linger_option, NEED_ARG,
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"keepalive", keepalive_option, 0,
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"spawn", spawn_option, NEED_ARG | EXPAND_ARG,
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"twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
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"rfc931", rfc931_option, OPT_ARG,
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"setenv", setenv_option, NEED_ARG | EXPAND_ARG,
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"nice", nice_option, OPT_ARG,
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"severity", severity_option, NEED_ARG,
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"allow", allow_option, USE_LAST,
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"deny", deny_option, USE_LAST,
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"banners", banners_option, NEED_ARG,
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0,
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};
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/* process_options - process access control options */
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void process_options(options, request)
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char *options;
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struct request_info *request;
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{
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char *key;
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char *value;
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char *curr_opt;
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char *next_opt;
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struct option *op;
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char bf[BUFSIZ];
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for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
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next_opt = get_field((char *) 0);
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/*
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* Separate the option into name and value parts. For backwards
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* compatibility we ignore exactly one '=' between name and value.
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*/
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curr_opt = chop_string(curr_opt);
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if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
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if (*value != '=') {
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*value++ = 0;
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value += strspn(value, whitespace);
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}
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if (*value == '=') {
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*value++ = 0;
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value += strspn(value, whitespace);
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}
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}
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if (*value == 0)
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value = 0;
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key = curr_opt;
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/*
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* Disallow missing option names (and empty option fields).
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*/
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if (*key == 0)
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tcpd_jump("missing option name");
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/*
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* Lookup the option-specific info and do some common error checks.
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* Delegate option-specific processing to the specific functions.
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*/
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for (op = option_table; op->name && STR_NE(op->name, key); op++)
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/* VOID */ ;
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if (op->name == 0)
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tcpd_jump("bad option name: \"%s\"", key);
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if (!value && need_arg(op))
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tcpd_jump("option \"%s\" requires value", key);
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if (value && !permit_arg(op))
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tcpd_jump("option \"%s\" requires no value", key);
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if (next_opt && use_last(op))
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tcpd_jump("option \"%s\" must be at end", key);
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if (value && expand_arg(op))
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value = chop_string(percent_x(bf, sizeof(bf), value, request));
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if (hosts_access_verbose)
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syslog(LOG_DEBUG, "option: %s %s", key, value ? value : "");
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(*(op->func)) (value, request);
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}
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}
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/* allow_option - grant access */
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/* ARGSUSED */
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static void allow_option(value, request)
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char *value;
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struct request_info *request;
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{
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longjmp(tcpd_buf, AC_PERMIT);
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}
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/* deny_option - deny access */
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/* ARGSUSED */
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static void deny_option(value, request)
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char *value;
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struct request_info *request;
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{
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longjmp(tcpd_buf, AC_DENY);
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}
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/* banners_option - expand %<char>, terminate each line with CRLF */
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static void banners_option(value, request)
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char *value;
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struct request_info *request;
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{
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char path[MAXPATHNAMELEN];
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char ibuf[BUFSIZ];
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char obuf[2 * BUFSIZ];
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struct stat st;
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int ch;
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FILE *fp;
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sprintf(path, "%s/%s", value, eval_daemon(request));
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if ((fp = fopen(path, "r")) != 0) {
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while ((ch = fgetc(fp)) == 0)
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write(request->fd, "", 1);
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ungetc(ch, fp);
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while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
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if (split_at(ibuf, '\n'))
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strcat(ibuf, "\r\n");
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percent_x(obuf, sizeof(obuf), ibuf, request);
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write(request->fd, obuf, strlen(obuf));
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}
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fclose(fp);
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} else if (stat(value, &st) < 0) {
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tcpd_warn("%s: %m", value);
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}
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}
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/* group_option - switch group id */
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/* ARGSUSED */
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static void group_option(value, request)
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char *value;
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struct request_info *request;
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{
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struct group *grp;
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struct group *getgrnam();
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if ((grp = getgrnam(value)) == 0)
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tcpd_jump("unknown group: \"%s\"", value);
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endgrent();
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if (dry_run == 0 && setgid(grp->gr_gid))
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tcpd_jump("setgid(%s): %m", value);
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}
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/* user_option - switch user id */
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/* ARGSUSED */
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static void user_option(value, request)
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char *value;
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struct request_info *request;
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{
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struct passwd *pwd;
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struct passwd *getpwnam();
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char *group;
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if ((group = split_at(value, '.')) != 0)
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group_option(group, request);
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if ((pwd = getpwnam(value)) == 0)
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tcpd_jump("unknown user: \"%s\"", value);
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endpwent();
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if (dry_run == 0 && setuid(pwd->pw_uid))
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tcpd_jump("setuid(%s): %m", value);
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}
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/* umask_option - set file creation mask */
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/* ARGSUSED */
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static void umask_option(value, request)
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char *value;
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struct request_info *request;
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{
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unsigned mask;
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char junk;
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if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
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tcpd_jump("bad umask value: \"%s\"", value);
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(void) umask(mask);
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}
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/* spawn_option - spawn a shell command and wait */
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/* ARGSUSED */
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static void spawn_option(value, request)
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char *value;
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struct request_info *request;
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{
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if (dry_run == 0)
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shell_cmd(value);
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}
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/* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
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/* ARGSUSED */
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static void linger_option(value, request)
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char *value;
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struct request_info *request;
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{
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struct linger linger;
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char junk;
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if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
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|| linger.l_linger < 0)
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tcpd_jump("bad linger value: \"%s\"", value);
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if (dry_run == 0) {
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linger.l_onoff = (linger.l_linger != 0);
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if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
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sizeof(linger)) < 0)
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tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
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}
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}
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/* keepalive_option - set the socket keepalive option */
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/* ARGSUSED */
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static void keepalive_option(value, request)
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char *value;
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struct request_info *request;
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{
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static int on = 1;
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if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
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(char *) &on, sizeof(on)) < 0)
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tcpd_warn("setsockopt SO_KEEPALIVE: %m");
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}
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/* nice_option - set nice value */
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/* ARGSUSED */
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static void nice_option(value, request)
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char *value;
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struct request_info *request;
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{
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int niceval = 10;
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char junk;
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if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
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tcpd_jump("bad nice value: \"%s\"", value);
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if (dry_run == 0 && nice(niceval) < 0)
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tcpd_warn("nice(%d): %m", niceval);
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}
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/* twist_option - replace process by shell command */
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static void twist_option(value, request)
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char *value;
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struct request_info *request;
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{
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char *error;
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if (dry_run != 0) {
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dry_run = 0;
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} else {
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if (resident > 0)
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tcpd_jump("twist option in resident process");
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syslog(deny_severity, "twist %s to %s", eval_client(request), value);
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/* Before switching to the shell, set up stdin, stdout and stderr. */
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#define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
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if (maybe_dup2(request->fd, 0) != 0 ||
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maybe_dup2(request->fd, 1) != 1 ||
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maybe_dup2(request->fd, 2) != 2) {
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error = "twist_option: dup: %m";
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} else {
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if (request->fd > 2)
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close(request->fd);
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(void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
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error = "twist_option: /bin/sh: %m";
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}
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/* Something went wrong: we MUST terminate the process. */
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tcpd_warn(error);
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clean_exit(request);
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}
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}
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/* rfc931_option - look up remote user name */
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static void rfc931_option(value, request)
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char *value;
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struct request_info *request;
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{
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int timeout;
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char junk;
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if (value != 0) {
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if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
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tcpd_jump("bad rfc931 timeout: \"%s\"", value);
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rfc931_timeout = timeout;
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}
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(void) eval_user(request);
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}
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/* setenv_option - set environment variable */
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/* ARGSUSED */
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static void setenv_option(value, request)
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char *value;
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struct request_info *request;
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{
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char *var_value;
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if (*(var_value = value + strcspn(value, whitespace)))
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*var_value++ = 0;
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if (setenv(chop_string(value), chop_string(var_value), 1))
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tcpd_jump("memory allocation failure");
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}
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/*
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* The severity option goes last because it comes with a huge amount of ugly
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* #ifdefs and tables.
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*/
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struct syslog_names {
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char *name;
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int value;
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};
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static struct syslog_names log_fac[] = {
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#ifdef LOG_KERN
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"kern", LOG_KERN,
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#endif
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#ifdef LOG_USER
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"user", LOG_USER,
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#endif
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#ifdef LOG_MAIL
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"mail", LOG_MAIL,
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#endif
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#ifdef LOG_DAEMON
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"daemon", LOG_DAEMON,
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#endif
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#ifdef LOG_AUTH
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"auth", LOG_AUTH,
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#endif
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#ifdef LOG_LPR
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"lpr", LOG_LPR,
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#endif
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#ifdef LOG_NEWS
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"news", LOG_NEWS,
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#endif
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#ifdef LOG_UUCP
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"uucp", LOG_UUCP,
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#endif
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#ifdef LOG_CRON
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"cron", LOG_CRON,
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#endif
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#ifdef LOG_LOCAL0
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"local0", LOG_LOCAL0,
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#endif
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#ifdef LOG_LOCAL1
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"local1", LOG_LOCAL1,
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#endif
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#ifdef LOG_LOCAL2
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"local2", LOG_LOCAL2,
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#endif
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#ifdef LOG_LOCAL3
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"local3", LOG_LOCAL3,
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#endif
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#ifdef LOG_LOCAL4
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"local4", LOG_LOCAL4,
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#endif
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#ifdef LOG_LOCAL5
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"local5", LOG_LOCAL5,
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#endif
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#ifdef LOG_LOCAL6
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"local6", LOG_LOCAL6,
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#endif
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#ifdef LOG_LOCAL7
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"local7", LOG_LOCAL7,
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#endif
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0,
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};
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static struct syslog_names log_sev[] = {
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#ifdef LOG_EMERG
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"emerg", LOG_EMERG,
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#endif
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#ifdef LOG_ALERT
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"alert", LOG_ALERT,
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#endif
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#ifdef LOG_CRIT
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"crit", LOG_CRIT,
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#endif
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#ifdef LOG_ERR
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"err", LOG_ERR,
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#endif
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#ifdef LOG_WARNING
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"warning", LOG_WARNING,
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#endif
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#ifdef LOG_NOTICE
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"notice", LOG_NOTICE,
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#endif
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#ifdef LOG_INFO
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"info", LOG_INFO,
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#endif
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#ifdef LOG_DEBUG
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"debug", LOG_DEBUG,
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#endif
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0,
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};
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/* severity_map - lookup facility or severity value */
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static int severity_map(table, name)
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struct syslog_names *table;
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char *name;
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{
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struct syslog_names *t;
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for (t = table; t->name; t++)
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if (STR_EQ(t->name, name))
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return (t->value);
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tcpd_jump("bad syslog facility or severity: \"%s\"", name);
|
|
/* NOTREACHED */
|
|
}
|
|
|
|
/* severity_option - change logging severity for this event (Dave Mitchell) */
|
|
|
|
/* ARGSUSED */
|
|
|
|
static void severity_option(value, request)
|
|
char *value;
|
|
struct request_info *request;
|
|
{
|
|
char *level = split_at(value, '.');
|
|
|
|
allow_severity = deny_severity = level ?
|
|
severity_map(log_fac, value) | severity_map(log_sev, level) :
|
|
severity_map(log_sev, value);
|
|
}
|
|
|
|
/* get_field - return pointer to next field in string */
|
|
|
|
static char *get_field(string)
|
|
char *string;
|
|
{
|
|
static char *last = "";
|
|
char *src;
|
|
char *dst;
|
|
char *ret;
|
|
int ch;
|
|
|
|
/*
|
|
* This function returns pointers to successive fields within a given
|
|
* string. ":" is the field separator; warn if the rule ends in one. It
|
|
* replaces a "\:" sequence by ":", without treating the result of
|
|
* substitution as field terminator. A null argument means resume search
|
|
* where the previous call terminated. This function destroys its
|
|
* argument.
|
|
*
|
|
* Work from explicit source or from memory. While processing \: we
|
|
* overwrite the input. This way we do not have to maintain buffers for
|
|
* copies of input fields.
|
|
*/
|
|
|
|
src = dst = ret = (string ? string : last);
|
|
if (src[0] == 0)
|
|
return (0);
|
|
|
|
while (ch = *src) {
|
|
if (ch == ':') {
|
|
if (*++src == 0)
|
|
tcpd_warn("rule ends in \":\"");
|
|
break;
|
|
}
|
|
if (ch == '\\' && src[1] == ':')
|
|
src++;
|
|
*dst++ = *src++;
|
|
}
|
|
last = src;
|
|
*dst = 0;
|
|
return (ret);
|
|
}
|
|
|
|
/* chop_string - strip leading and trailing blanks from string */
|
|
|
|
static char *chop_string(string)
|
|
register char *string;
|
|
{
|
|
char *start = 0;
|
|
char *end;
|
|
char *cp;
|
|
|
|
for (cp = string; *cp; cp++) {
|
|
if (!isspace(*cp)) {
|
|
if (start == 0)
|
|
start = cp;
|
|
end = cp;
|
|
}
|
|
}
|
|
return (start ? (end[1] = 0, start) : cp);
|
|
}
|