xref: /freebsd/sbin/ggate/ggated/ggated.c (revision d37ea99837e6ad50837fd9fe1771ddf1c3ba6002)
1 /*-
2  * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <stdint.h>
32 #include <unistd.h>
33 #include <fcntl.h>
34 #include <sys/param.h>
35 #include <sys/queue.h>
36 #include <sys/endian.h>
37 #include <sys/socket.h>
38 #include <sys/ioctl.h>
39 #include <sys/stat.h>
40 #include <sys/time.h>
41 #include <sys/disk.h>
42 #include <sys/bio.h>
43 #include <netinet/in.h>
44 #include <netinet/tcp.h>
45 #include <arpa/inet.h>
46 #include <signal.h>
47 #include <err.h>
48 #include <errno.h>
49 #include <string.h>
50 #include <libgen.h>
51 #include <syslog.h>
52 #include <stdarg.h>
53 
54 #include <geom/gate/g_gate.h>
55 #include "ggate.h"
56 
57 
58 #define	G_GATED_EXPORT_FILE	"/etc/gg.exports"
59 #define	G_GATED_DEBUG(...)						\
60 	if (g_gate_verbose) {						\
61 		printf(__VA_ARGS__);					\
62 		printf("\n");						\
63 	}
64 
65 static const char *exports = G_GATED_EXPORT_FILE;
66 static int got_sighup = 0;
67 static int nagle = 1;
68 static unsigned rcvbuf = G_GATE_RCVBUF;
69 static unsigned sndbuf = G_GATE_SNDBUF;
70 
71 struct export {
72 	char		*e_path;	/* path to device/file */
73 	in_addr_t	 e_ip;		/* remote IP address */
74 	in_addr_t	 e_mask;	/* IP mask */
75 	unsigned	 e_flags;	/* flags (RO/RW) */
76 	SLIST_ENTRY(export) e_next;
77 };
78 static SLIST_HEAD(, export) exports_list =
79     SLIST_HEAD_INITIALIZER(&exports_list);
80 
81 static void
82 usage(void)
83 {
84 
85 	fprintf(stderr, "usage: %s [-nv] [-a address] [-p port] [-R rcvbuf] "
86 	    "[-S sndbuf] [exports file]\n", getprogname());
87 	exit(EXIT_FAILURE);
88 }
89 
90 static char *
91 ip2str(in_addr_t ip)
92 {
93 	static char sip[16];
94 
95 	snprintf(sip, sizeof(sip), "%u.%u.%u.%u",
96 	    ((ip >> 24) & 0xff),
97 	    ((ip >> 16) & 0xff),
98 	    ((ip >> 8) & 0xff),
99 	    (ip & 0xff));
100 	return (sip);
101 }
102 
103 static in_addr_t
104 countmask(unsigned m)
105 {
106 	in_addr_t mask;
107 
108 	if (m == 0) {
109 		mask = 0x0;
110 	} else {
111 		mask = 1 << (32 - m);
112 		mask--;
113 		mask = ~mask;
114 	}
115 	return (mask);
116 }
117 
118 static void
119 line_parse(char *line, unsigned lineno)
120 {
121 	struct export *ex;
122 	char *word, *path, *sflags;
123 	unsigned flags, i, vmask;
124 	in_addr_t ip, mask;
125 
126 	ip = mask = flags = vmask = 0;
127 	path = NULL;
128 	sflags = NULL;
129 
130 	for (i = 0, word = strtok(line, " \t"); word != NULL;
131 	    i++, word = strtok(NULL, " \t")) {
132 		switch (i) {
133 		case 0: /* IP address or host name */
134 			ip = g_gate_str2ip(strsep(&word, "/"));
135 			if (ip == INADDR_NONE) {
136 				g_gate_xlog("Invalid IP/host name at line %u.",
137 				    lineno);
138 			}
139 			ip = ntohl(ip);
140 			if (word == NULL)
141 				vmask = 32;
142 			else {
143 				errno = 0;
144 				vmask = strtoul(word, NULL, 10);
145 				if (vmask == 0 && errno != 0) {
146 					g_gate_xlog("Invalid IP mask value at "
147 					    "line %u.", lineno);
148 				}
149 				if ((unsigned)vmask > 32) {
150 					g_gate_xlog("Invalid IP mask value at line %u.",
151 					    lineno);
152 				}
153 			}
154 			mask = countmask(vmask);
155 			break;
156 		case 1:	/* flags */
157 			if (strcasecmp("rd", word) == 0 ||
158 			    strcasecmp("ro", word) == 0) {
159 				flags = O_RDONLY;
160 			} else if (strcasecmp("wo", word) == 0) {
161 				flags = O_WRONLY;
162 			} else if (strcasecmp("rw", word) == 0) {
163 				flags = O_RDWR;
164 			} else {
165 				g_gate_xlog("Invalid value in flags field at "
166 				    "line %u.", lineno);
167 			}
168 			sflags = word;
169 			break;
170 		case 2:	/* path */
171 			if (strlen(word) >= MAXPATHLEN) {
172 				g_gate_xlog("Path too long at line %u. ",
173 				    lineno);
174 			}
175 			path = word;
176 			break;
177 		default:
178 			g_gate_xlog("Too many arguments at line %u. ", lineno);
179 		}
180 	}
181 	if (i != 3)
182 		g_gate_xlog("Too few arguments at line %u.", lineno);
183 
184 	ex = malloc(sizeof(*ex));
185 	if (ex == NULL)
186 		g_gate_xlog("No enough memory.");
187 	ex->e_path = strdup(path);
188 	if (ex->e_path == NULL)
189 		g_gate_xlog("No enough memory.");
190 
191 	/* Made 'and' here. */
192 	ex->e_ip = (ip & mask);
193 	ex->e_mask = mask;
194 	ex->e_flags = flags;
195 
196 	SLIST_INSERT_HEAD(&exports_list, ex, e_next);
197 
198 	g_gate_log(LOG_DEBUG, "Added %s/%u %s %s to exports list.",
199 	    ip2str(ex->e_ip), vmask, path, sflags);
200 }
201 
202 static void
203 exports_clear(void)
204 {
205 	struct export *ex;
206 
207 	while (!SLIST_EMPTY(&exports_list)) {
208 		ex = SLIST_FIRST(&exports_list);
209 		SLIST_REMOVE_HEAD(&exports_list, e_next);
210 		free(ex);
211 	}
212 }
213 
214 #define	EXPORTS_LINE_SIZE	2048
215 static void
216 exports_get(void)
217 {
218 	char buf[EXPORTS_LINE_SIZE], *line;
219 	unsigned lineno = 0, objs = 0, len;
220 	FILE *fd;
221 
222 	exports_clear();
223 
224 	fd = fopen(exports, "r");
225 	if (fd == NULL) {
226 		g_gate_xlog("Cannot open exports file (%s): %s.", exports,
227 		    strerror(errno));
228 	}
229 
230 	g_gate_log(LOG_INFO, "Reading exports file (%s).", exports);
231 
232 	for (;;) {
233 		if (fgets(buf, sizeof(buf), fd) == NULL) {
234 			if (feof(fd))
235 				break;
236 
237 			g_gate_xlog("Error while reading exports file: %s.",
238 			    strerror(errno));
239 		}
240 
241 		/* Increase line count. */
242 		lineno++;
243 
244 		/* Skip spaces and tabs. */
245 		for (line = buf; *line == ' ' || *line == '\t'; ++line)
246 			;
247 
248 		/* Empty line, comment or empty line at the end of file. */
249 		if (*line == '\n' || *line == '#' || *line == '\0')
250 			continue;
251 
252 		len = strlen(line);
253 		if (line[len - 1] == '\n') {
254 			/* Remove new line char. */
255 			line[len - 1] = '\0';
256 		} else {
257 			if (!feof(fd))
258 				g_gate_xlog("Line %u too long.", lineno);
259 		}
260 
261 		line_parse(line, lineno);
262 		objs++;
263 	}
264 
265 	fclose(fd);
266 
267 	if (objs == 0)
268 		g_gate_xlog("There are no objects to export.");
269 
270 	g_gate_log(LOG_INFO, "Exporting %u object(s).", objs);
271 }
272 
273 static struct export *
274 exports_find(struct sockaddr *s, const char *path)
275 {
276 	struct export *ex;
277 	in_addr_t ip;
278 
279 	ip = htonl(((struct sockaddr_in *)(void *)s)->sin_addr.s_addr);
280 	SLIST_FOREACH(ex, &exports_list, e_next) {
281 		if ((ip & ex->e_mask) != ex->e_ip)
282 			continue;
283 		if (path != NULL && strcmp(path, ex->e_path) != 0)
284 			continue;
285 
286 		g_gate_log(LOG_INFO, "Connection from: %s.", ip2str(ip));
287 		return (ex);
288 	}
289 	g_gate_log(LOG_INFO, "Unauthorized connection from: %s.", ip2str(ip));
290 
291 	return (NULL);
292 }
293 
294 static void
295 sendfail(int sfd, int error, const char *fmt, ...)
296 {
297 	struct g_gate_sinit sinit;
298 	va_list ap;
299 	int data;
300 
301 	sinit.gs_error = error;
302 	g_gate_swap2n_sinit(&sinit);
303 	data = send(sfd, &sinit, sizeof(sinit), 0);
304 	g_gate_swap2h_sinit(&sinit);
305 	if (data == -1) {
306 		g_gate_xlog("Error while sending initial packet: %s.",
307 		    strerror(errno));
308 	}
309 	if (fmt != NULL) {
310 		va_start(ap, fmt);
311 		g_gate_xvlog(fmt, ap);
312 		/* NOTREACHED */
313 		va_end(ap);
314 	}
315 	exit(EXIT_FAILURE);
316 }
317 
318 static void
319 serve(int sfd, struct sockaddr *s)
320 {
321 	struct g_gate_cinit cinit;
322 	struct g_gate_sinit sinit;
323 	struct g_gate_hdr hdr;
324 	struct export *ex;
325 	char ipmask[32]; /* 32 == strlen("xxx.xxx.xxx.xxx/xxx.xxx.xxx.xxx")+1 */
326 	size_t bufsize;
327 	int32_t error;
328 	int fd, flags;
329 	ssize_t data;
330 	char *buf;
331 
332 	g_gate_log(LOG_DEBUG, "Receiving initial packet.");
333 	data = recv(sfd, &cinit, sizeof(cinit), MSG_WAITALL);
334 	g_gate_swap2h_cinit(&cinit);
335 	if (data == -1) {
336 		g_gate_xlog("Error while receiving initial packet: %s.",
337 		    strerror(errno));
338 	}
339 
340 	ex = exports_find(s, cinit.gc_path);
341 	if (ex == NULL) {
342 		sendfail(sfd, EINVAL, "Requested path isn't exported: %s.",
343 		    strerror(errno));
344 	}
345 
346 	error = 0;
347 	strlcpy(ipmask, ip2str(ex->e_ip), sizeof(ipmask));
348 	strlcat(ipmask, "/", sizeof(ipmask));
349 	strlcat(ipmask, ip2str(ex->e_mask), sizeof(ipmask));
350 	if ((cinit.gc_flags & G_GATE_FLAG_READONLY) != 0) {
351 		if (ex->e_flags == O_WRONLY) {
352 			g_gate_log(LOG_ERR, "Read-only access requested, but "
353 			    "%s (%s) is exported write-only.", ex->e_path,
354 			    ipmask);
355 			error = EPERM;
356 		} else {
357 			sinit.gs_flags = G_GATE_FLAG_READONLY;
358 		}
359 	} else if ((cinit.gc_flags & G_GATE_FLAG_WRITEONLY) != 0) {
360 		if (ex->e_flags == O_RDONLY) {
361 			g_gate_log(LOG_ERR, "Write-only access requested, but "
362 			    "%s (%s) is exported read-only.", ex->e_path,
363 			    ipmask);
364 			error = EPERM;
365 		} else {
366 			sinit.gs_flags = G_GATE_FLAG_WRITEONLY;
367 		}
368 	} else {
369 		if (ex->e_flags == O_RDONLY) {
370 			g_gate_log(LOG_ERR, "Read-write access requested, but "
371 			    "%s (%s) is exported read-only.", ex->e_path,
372 			    ipmask);
373 			error = EPERM;
374 		} else if (ex->e_flags == O_WRONLY) {
375 			g_gate_log(LOG_ERR, "Read-write access requested, but "
376 			    "%s (%s) is exported write-only.", ex->e_path,
377 			    ipmask);
378 			error = EPERM;
379 		} else {
380 			sinit.gs_flags = 0;
381 		}
382 	}
383 	if (error != 0)
384 		sendfail(sfd, error, NULL);
385 	flags = g_gate_openflags(sinit.gs_flags);
386 	fd = open(ex->e_path, flags);
387 	if (fd < 0) {
388 		sendfail(sfd, errno, "Error while opening %s: %s.", ex->e_path,
389 		    strerror(errno));
390 	}
391 
392 	g_gate_log(LOG_DEBUG, "Sending initial packet.");
393 	/*
394 	 * This field isn't used by ggc(8) for now.
395 	 * It should be used in future when user don't give device size.
396 	 */
397 	sinit.gs_mediasize = g_gate_mediasize(fd);
398 	sinit.gs_sectorsize = g_gate_sectorsize(fd);
399 	sinit.gs_error = 0;
400 	g_gate_swap2n_sinit(&sinit);
401 	data = send(sfd, &sinit, sizeof(sinit), 0);
402 	g_gate_swap2h_sinit(&sinit);
403 	if (data == -1) {
404 		sendfail(sfd, errno, "Error while sending initial packet: %s.",
405 		    strerror(errno));
406 	}
407 
408 	bufsize = G_GATE_BUFSIZE_START;
409 	buf = malloc(bufsize);
410 	if (buf == NULL)
411 		g_gate_xlog("No enough memory.");
412 
413 	g_gate_log(LOG_DEBUG, "New process: %u.", getpid());
414 
415 	for (;;) {
416 		/*
417 		 * Receive request.
418 		 */
419 		data = recv(sfd, &hdr, sizeof(hdr), MSG_WAITALL);
420 		if (data == 0) {
421 			g_gate_log(LOG_DEBUG, "Process %u exiting.", getpid());
422 			exit(EXIT_SUCCESS);
423 		} else if (data == -1) {
424 			g_gate_xlog("Error while receiving hdr packet: %s.",
425 			    strerror(errno));
426 		} else if (data != sizeof(hdr)) {
427 			g_gate_xlog("Malformed hdr packet received.");
428 		}
429 		g_gate_log(LOG_DEBUG, "Received hdr packet.");
430 		g_gate_swap2h_hdr(&hdr);
431 
432 		/*
433 		 * Increase buffer if there is need to.
434 		 */
435 		if (hdr.gh_length > bufsize) {
436 			bufsize = hdr.gh_length;
437 			g_gate_log(LOG_DEBUG, "Increasing buffer to %u.",
438 			    bufsize);
439 			buf = realloc(buf, bufsize);
440 			if (buf == NULL)
441 				g_gate_xlog("No enough memory.");
442 		}
443 
444 		if (hdr.gh_cmd == BIO_READ) {
445 			if (pread(fd, buf, hdr.gh_length,
446 			    hdr.gh_offset) == -1) {
447 				error = errno;
448 				g_gate_log(LOG_ERR, "Error while reading data "
449 				    "(offset=%ju, size=%zu): %s.",
450 				    (uintmax_t)hdr.gh_offset,
451 				    (size_t)hdr.gh_length, strerror(error));
452 			} else {
453 				error = 0;
454 			}
455 			hdr.gh_error = error;
456 			g_gate_swap2n_hdr(&hdr);
457 			if (send(sfd, &hdr, sizeof(hdr), 0) == -1) {
458 				g_gate_xlog("Error while sending status: %s.",
459 				    strerror(errno));
460 			}
461 			g_gate_swap2h_hdr(&hdr);
462 			/* Send data only if there was no error while pread(). */
463 			if (error == 0) {
464 				data = send(sfd, buf, hdr.gh_length, 0);
465 				if (data == -1) {
466 					g_gate_xlog("Error while sending data: "
467 					    "%s.", strerror(errno));
468 				}
469 				g_gate_log(LOG_DEBUG, "Sent %d bytes "
470 				    "(offset=%ju, size=%zu).", data,
471 				    (uintmax_t)hdr.gh_offset,
472 				    (size_t)hdr.gh_length);
473 			}
474 		} else /* if (hdr.gh_cmd == BIO_WRITE) */ {
475 			g_gate_log(LOG_DEBUG, "Waiting for %u bytes of data...",
476 			    hdr.gh_length);
477 			data = recv(sfd, buf, hdr.gh_length, MSG_WAITALL);
478 			if (data == -1) {
479 				g_gate_xlog("Error while receiving data: %s.",
480 				    strerror(errno));
481 			}
482 			if (pwrite(fd, buf, hdr.gh_length, hdr.gh_offset) == -1) {
483 				error = errno;
484 				g_gate_log(LOG_ERR, "Error while writing data "
485 				    "(offset=%llu, size=%u): %s.",
486 				    hdr.gh_offset, hdr.gh_length,
487 				    strerror(error));
488 			} else {
489 				error = 0;
490 			}
491 			hdr.gh_error = error;
492 			g_gate_swap2n_hdr(&hdr);
493 			if (send(sfd, &hdr, sizeof(hdr), 0) == -1) {
494 				g_gate_xlog("Error while sending status: %s.",
495 				    strerror(errno));
496 			}
497 			g_gate_swap2h_hdr(&hdr);
498 			g_gate_log(LOG_DEBUG, "Received %d bytes (offset=%llu, "
499 			    "size=%u).", data, hdr.gh_offset, hdr.gh_length);
500 		}
501 		g_gate_log(LOG_DEBUG, "Tick.");
502 	}
503 }
504 
505 static void
506 huphandler(int sig __unused)
507 {
508 
509 	got_sighup = 1;
510 }
511 
512 int
513 main(int argc, char *argv[])
514 {
515 	struct sockaddr_in serv;
516 	struct sockaddr from;
517 	in_addr_t bindaddr;
518 	socklen_t fromlen;
519 	struct timeval tv;
520 	int on, sfd, tmpsfd;
521 	pid_t childpid;
522 	unsigned bsize, port;
523 
524 	bindaddr = htonl(INADDR_ANY);
525 	port = G_GATE_PORT;
526 	for (;;) {
527 		int ch;
528 
529 		ch = getopt(argc, argv, "a:hnp:R:S:v");
530 		if (ch == -1)
531 			break;
532 		switch (ch) {
533 		case 'a':
534 			bindaddr = g_gate_str2ip(optarg);
535 			if (bindaddr == INADDR_NONE) {
536 				errx(EXIT_FAILURE,
537 				    "Invalid IP/host name to bind to.");
538 			}
539 			break;
540 		case 'n':
541 			nagle = 0;
542 			break;
543 		case 'p':
544 			errno = 0;
545 			port = strtoul(optarg, NULL, 10);
546 			if (port == 0 && errno != 0)
547 				errx(EXIT_FAILURE, "Invalid port.");
548 			break;
549 		case 'R':
550 			errno = 0;
551 			rcvbuf = strtoul(optarg, NULL, 10);
552 			if (rcvbuf == 0 && errno != 0)
553 				errx(EXIT_FAILURE, "Invalid rcvbuf.");
554 			break;
555 		case 'S':
556 			errno = 0;
557 			sndbuf = strtoul(optarg, NULL, 10);
558 			if (sndbuf == 0 && errno != 0)
559 				errx(EXIT_FAILURE, "Invalid sndbuf.");
560 			break;
561 		case 'v':
562 			g_gate_verbose++;
563 			break;
564 		case 'h':
565 		default:
566 			usage();
567 		}
568 	}
569 	argc -= optind;
570 	argv += optind;
571 
572 	if (argv[0] != NULL)
573 		exports = argv[0];
574 	exports_get();
575 
576 	if (!g_gate_verbose) {
577 		/* Run in daemon mode. */
578 		if (daemon(0, 0) < 0)
579 			g_gate_xlog("Can't daemonize: %s", strerror(errno));
580 	}
581 
582 	signal(SIGCHLD, SIG_IGN);
583 
584 	sfd = socket(AF_INET, SOCK_STREAM, 0);
585 	if (sfd < 0)
586 		g_gate_xlog("Can't open stream socket: %s.", strerror(errno));
587 	bzero(&serv, sizeof(serv));
588 	serv.sin_family = AF_INET;
589 	serv.sin_addr.s_addr = bindaddr;
590 	serv.sin_port = htons(port);
591 	on = 1;
592 	if (nagle) {
593 		if (setsockopt(sfd, IPPROTO_TCP, TCP_NODELAY, &on,
594 		    sizeof(on)) < 0) {
595 			g_gate_xlog("setsockopt() error: %s.", strerror(errno));
596 		}
597 	}
598 	if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)
599 		g_gate_xlog("setsockopt(): %s.", strerror(errno));
600 	bsize = rcvbuf;
601 	if (setsockopt(sfd, SOL_SOCKET, SO_RCVBUF, &bsize, sizeof(bsize)) < 0)
602 		g_gate_xlog("setsockopt(): %s.", strerror(errno));
603 	bsize = sndbuf;
604 	if (setsockopt(sfd, SOL_SOCKET, SO_SNDBUF, &bsize, sizeof(bsize)) < 0)
605 		g_gate_xlog("setsockopt(): %s.", strerror(errno));
606 	tv.tv_sec = 10;
607 	tv.tv_usec = 0;
608 	if (setsockopt(sfd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) ||
609 	    setsockopt(sfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
610 		g_gate_xlog("setsockopt() error: %s.", strerror(errno));
611 	}
612 	if (bind(sfd, (struct sockaddr *)&serv, sizeof(serv)) < 0)
613 		g_gate_xlog("bind(): %s.", strerror(errno));
614 	if (listen(sfd, 5) < 0)
615 		g_gate_xlog("listen(): %s.", strerror(errno));
616 
617 	g_gate_log(LOG_INFO, "Listen on port: %d.", port);
618 
619 	signal(SIGHUP, huphandler);
620 
621 	for (;;) {
622 		fromlen = sizeof(from);
623 		tmpsfd = accept(sfd, &from, &fromlen);
624 		if (tmpsfd < 0)
625 			g_gate_xlog("accept(): %s.", strerror(errno));
626 
627 		if (got_sighup) {
628 			got_sighup = 0;
629 			exports_get();
630 		}
631 
632 		if (exports_find(&from, NULL) == NULL) {
633 			close(tmpsfd);
634 			continue;
635 		}
636 
637 		childpid = fork();
638 		if (childpid < 0) {
639 			g_gate_xlog("Cannot create child process: %s.",
640 			    strerror(errno));
641 		} else if (childpid == 0) {
642 			close(sfd);
643 			serve(tmpsfd, &from);
644 			/* NOTREACHED */
645 		}
646 		close(tmpsfd);
647 	}
648 	close(sfd);
649 	exit(EXIT_SUCCESS);
650 }
651