1/*	$OpenBSD: ttymsg.c,v 1.19 2021/09/03 16:28:33 bluhm Exp $	*/
2/*	$NetBSD: ttymsg.c,v 1.3 1994/11/17 07:17:55 jtc Exp $	*/
3
4/*
5 * Copyright (c) 2014-2017 Alexander Bluhm <bluhm@genua.de>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20/*
21 * Copyright (c) 1989, 1993
22 *	The Regents of the University of California.  All rights reserved.
23 *
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
26 * are met:
27 * 1. Redistributions of source code must retain the above copyright
28 *    notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 *    notice, this list of conditions and the following disclaimer in the
31 *    documentation and/or other materials provided with the distribution.
32 * 3. Neither the name of the University nor the names of its contributors
33 *    may be used to endorse or promote products derived from this software
34 *    without specific prior written permission.
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
37 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
39 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
40 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
41 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
42 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
44 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
45 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46 * SUCH DAMAGE.
47 */
48
49#include <sys/stat.h>
50#include <sys/syslog.h>
51
52#include <dirent.h>
53#include <errno.h>
54#include <event.h>
55#include <paths.h>
56#include <signal.h>
57#include <stdio.h>
58#include <stdlib.h>
59#include <string.h>
60#include <unistd.h>
61
62#include "log.h"
63#include "syslogd.h"
64
65struct tty_delay {
66	struct event	 td_event;
67	size_t		 td_length;
68	char		 td_line[LOG_MAXLINE];
69};
70int tty_delayed = 0;
71void ttycb(int, short, void *);
72
73/*
74 * Display the contents of a uio structure on a terminal.
75 * Schedules an event if write would block, waiting up to TTYMSGTIME
76 * seconds.
77 */
78void
79ttymsg(char *utline, struct iovec *iov)
80{
81	static char device[MAXNAMLEN] = _PATH_DEV;
82	struct iovec localiov[IOVCNT];
83	int iovcnt = IOVCNT;
84	int cnt, fd;
85	size_t left;
86	ssize_t wret;
87
88	/*
89	 * Ignore lines that start with "ftp" or "uucp".
90	 */
91	if ((strncmp(utline, "ftp", 3) == 0) ||
92	    (strncmp(utline, "uucp", 4) == 0))
93		return;
94
95	(void) strlcpy(device + sizeof(_PATH_DEV) - 1, utline,
96	    sizeof(device) - (sizeof(_PATH_DEV) - 1));
97	if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) {
98		/* A slash is an attempt to break security... */
99		log_warnx("'/' in tty device \"%s\"", device);
100		return;
101	}
102
103	/*
104	 * open will fail on slip lines or exclusive-use lines
105	 * if not running as root; not an error.
106	 */
107	if ((fd = priv_open_tty(device)) == -1) {
108		if (errno != EBUSY && errno != EACCES)
109			log_warn("priv_open_tty device \"%s\"", device);
110		return;
111	}
112
113	left = 0;
114	for (cnt = 0; cnt < iovcnt; ++cnt)
115		left += iov[cnt].iov_len;
116
117	for (;;) {
118		wret = writev(fd, iov, iovcnt);
119		if (wret >= 0) {
120			if ((size_t)wret >= left)
121				break;
122			left -= wret;
123			if (iov != localiov) {
124				memmove(localiov, iov,
125				    iovcnt * sizeof(struct iovec));
126				iov = localiov;
127			}
128			while ((size_t)wret >= iov->iov_len) {
129				wret -= iov->iov_len;
130				++iov;
131				--iovcnt;
132			}
133			if (wret) {
134				iov->iov_base = (char *)iov->iov_base + wret;
135				iov->iov_len -= wret;
136			}
137			continue;
138		}
139		if (errno == EWOULDBLOCK) {
140			struct tty_delay	*td;
141			struct timeval		 to;
142
143			if (tty_delayed >= TTYMAXDELAY) {
144				log_warnx("tty device \"%s\": %s",
145				    device, "too many delayed writes");
146				break;
147			}
148			log_debug("ttymsg delayed write");
149			if (iov != localiov) {
150				memmove(localiov, iov,
151				    iovcnt * sizeof(struct iovec));
152				iov = localiov;
153			}
154			if ((td = malloc(sizeof(*td))) == NULL) {
155				log_warn("allocate delay tty device \"%s\"",
156				    device);
157				break;
158			}
159			td->td_length = 0;
160			if (left > LOG_MAXLINE)
161				left = LOG_MAXLINE;
162			while (iovcnt && left) {
163				if (iov->iov_len > left)
164					iov->iov_len = left;
165				memcpy(td->td_line + td->td_length,
166				    iov->iov_base, iov->iov_len);
167				td->td_length += iov->iov_len;
168				left -= iov->iov_len;
169				++iov;
170				--iovcnt;
171			}
172			tty_delayed++;
173			event_set(&td->td_event, fd, EV_WRITE, ttycb, td);
174			to.tv_sec = TTYMSGTIME;
175			to.tv_usec = 0;
176			event_add(&td->td_event, &to);
177			return;
178		}
179		/*
180		 * We get ENODEV on a slip line if we're running as root,
181		 * and EIO if the line just went away.
182		 */
183		if (errno != ENODEV && errno != EIO)
184			log_warn("writev tty device \"%s\"", device);
185		break;
186	}
187
188	(void) close(fd);
189	return;
190}
191
192void
193ttycb(int fd, short event, void *arg)
194{
195	struct tty_delay	*td = arg;
196	struct timeval		 to;
197	ssize_t			 wret;
198
199	if (event != EV_WRITE)
200		goto done;
201
202	wret = write(fd, td->td_line, td->td_length);
203	if (wret == -1 && errno != EINTR && errno != EWOULDBLOCK)
204		goto done;
205	if (wret > 0) {
206		td->td_length -= wret;
207		if (td->td_length == 0)
208			goto done;
209		memmove(td->td_line, td->td_line + wret, td->td_length);
210	}
211	to.tv_sec = TTYMSGTIME;
212	to.tv_usec = 0;
213	event_add(&td->td_event, &to);
214	return;
215
216 done:
217	tty_delayed--;
218	close(fd);
219	free(td);
220}
221