xref: /netbsd-src/usr.bin/ftp/ssl.c (revision bafbd613d128806a1921666029a1af09a19e3f1c)
1 /*	$NetBSD: ssl.c,v 1.20 2024/09/25 16:53:58 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1998-2004 Dag-Erling Coïdan Smørgrav
5  * Copyright (c) 2008, 2010 Joerg Sonnenberger <joerg@NetBSD.org>
6  * Copyright (c) 2015 Thomas Klausner <wiz@NetBSD.org>
7  * Copyright (c) 2023 Michael van Elst <mlelstv@NetBSD.org>
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer
15  *    in this position and unchanged.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. The name of the author may not be used to endorse or promote products
20  *    derived from this software without specific prior written permission
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  *
33  * $FreeBSD: common.c,v 1.53 2007/12/19 00:26:36 des Exp $
34  */
35 
36 #include <sys/cdefs.h>
37 #ifndef lint
38 __RCSID("$NetBSD: ssl.c,v 1.20 2024/09/25 16:53:58 christos Exp $");
39 #endif
40 
41 #include <err.h>
42 #include <errno.h>
43 #include <fcntl.h>
44 #include <stdarg.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <time.h>
49 #include <unistd.h>
50 
51 #include <sys/param.h>
52 #include <sys/uio.h>
53 
54 #include <netinet/tcp.h>
55 #include <netinet/in.h>
56 
57 #ifdef WITH_SSL
58 #include <openssl/crypto.h>
59 #include <openssl/x509.h>
60 #include <openssl/pem.h>
61 #include <openssl/ssl.h>
62 #include <openssl/err.h>
63 #endif
64 
65 #include "ssl.h"
66 #include "ftp_var.h"
67 
68 extern int quit_time, verbose, ftp_debug;
69 extern FILE *ttyout;
70 
71 struct fetch_connect {
72 	int			 sd;		/* file/socket descriptor */
73 	char			*buf;		/* buffer */
74 	size_t			 bufsize;	/* buffer size */
75 	size_t			 bufpos;	/* position of buffer */
76 	size_t			 buflen;	/* length of buffer contents */
77 	struct {				/* data cached after an
78 						   interrupted read */
79 		char	*buf;
80 		size_t	 size;
81 		size_t	 pos;
82 		size_t	 len;
83 	} cache;
84 	int 			 issock;
85 	int			 iserr;
86 	int			 iseof;
87 #ifdef WITH_SSL
88 	SSL			*ssl;		/* SSL handle */
89 #endif
90 };
91 
92 /*
93  * Write a vector to a connection w/ timeout
94  * Note: can modify the iovec.
95  */
96 static ssize_t
97 fetch_writev(struct fetch_connect *conn, struct iovec *iov, int iovcnt)
98 {
99 	struct timeval timeout, now, delta;
100 	ssize_t len, total;
101 	int fd = conn->sd;
102 	int rv, timeout_secs;
103 	struct pollfd pfd[1];
104 
105 	pfd[0].fd = fd;
106 	pfd[0].events = POLLOUT;
107 	gettimeofday(&timeout, NULL);
108 	timeout.tv_sec += quit_time;
109 
110 	total = 0;
111 	while (iovcnt > 0) {
112 		if (quit_time > 0) {	/* enforce timeout */
113 			do {
114 				(void)gettimeofday(&now, NULL);
115 				timersub(&timeout, &now, &delta);
116 				timeout_secs = (int)(delta.tv_sec * 1000
117 				    + delta.tv_usec / 1000);
118 				if (timeout_secs < 0)
119 					timeout_secs = 0;
120 				rv = ftp_poll(pfd, 1, timeout_secs);
121 					/* loop until poll !EINTR && !EAGAIN */
122 			} while (rv == -1 && (errno == EINTR || errno == EAGAIN));
123 			if (rv == -1)
124 				return -1;
125 			if (rv == 0) {
126 				errno = ETIMEDOUT;
127 				return -1;
128 			}
129 		}
130 		errno = 0;
131 #ifdef WITH_SSL
132 		if (conn->ssl != NULL)
133 			len = SSL_write(conn->ssl, iov->iov_base, (int)iov->iov_len);
134 		else
135 #endif
136 			len = writev(fd, iov, iovcnt);
137 		if (len == 0) {
138 			/* we consider a short write a failure */
139 			/* XXX perhaps we shouldn't in the SSL case */
140 			errno = EPIPE;
141 			return -1;
142 		}
143 		if (len < 0) {
144 			if (errno == EINTR || errno == EAGAIN)
145 				continue;
146 			return -1;
147 		}
148 		total += len;
149 		while (iovcnt > 0 && len >= (ssize_t)iov->iov_len) {
150 			len -= iov->iov_len;
151 			iov++;
152 			iovcnt--;
153 		}
154 		if (iovcnt > 0) {
155 			iov->iov_len -= len;
156 			iov->iov_base = (char *)iov->iov_base + len;
157 		}
158 	}
159 	return total;
160 }
161 
162 static ssize_t
163 fetch_write(const void *str, size_t len, struct fetch_connect *conn)
164 {
165 	struct iovec iov[1];
166 
167 	iov[0].iov_base = (char *)__UNCONST(str);
168 	iov[0].iov_len = len;
169 	return fetch_writev(conn, iov, 1);
170 }
171 
172 /*
173  * Send a formatted line; optionally echo to terminal
174  */
175 int
176 fetch_printf(struct fetch_connect *conn, const char *fmt, ...)
177 {
178 	va_list ap;
179 	size_t len;
180 	char *msg;
181 	ssize_t r;
182 
183 	va_start(ap, fmt);
184 	len = vasprintf(&msg, fmt, ap);
185 	va_end(ap);
186 
187 	if (msg == NULL) {
188 		errno = ENOMEM;
189 		return -1;
190 	}
191 
192 	r = fetch_write(msg, len, conn);
193 	free(msg);
194 	return (int)r;
195 }
196 
197 int
198 fetch_fileno(struct fetch_connect *conn)
199 {
200 
201 	return conn->sd;
202 }
203 
204 int
205 fetch_error(struct fetch_connect *conn)
206 {
207 
208 	return conn->iserr;
209 }
210 
211 static void
212 fetch_clearerr(struct fetch_connect *conn)
213 {
214 
215 	conn->iserr = 0;
216 }
217 
218 int
219 fetch_flush(struct fetch_connect *conn)
220 {
221 
222 	if (conn->issock) {
223 		int fd = conn->sd;
224 		int v;
225 #ifdef TCP_NOPUSH
226 		v = 0;
227 		setsockopt(fd, IPPROTO_TCP, TCP_NOPUSH, &v, sizeof(v));
228 #endif
229 		v = 1;
230 		setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &v, sizeof(v));
231 	}
232 	return 0;
233 }
234 
235 /*ARGSUSED*/
236 struct fetch_connect *
237 fetch_open(const char *fname, const char *fmode)
238 {
239 	struct fetch_connect *conn;
240 	int fd;
241 
242 	fd = open(fname, O_RDONLY); /* XXX: fmode */
243 	if (fd < 0)
244 		return NULL;
245 
246 	if ((conn = calloc(1, sizeof(*conn))) == NULL) {
247 		close(fd);
248 		return NULL;
249 	}
250 
251 	conn->sd = fd;
252 	conn->issock = 0;
253 	return conn;
254 }
255 
256 /*ARGSUSED*/
257 struct fetch_connect *
258 fetch_fdopen(int sd, const char *fmode)
259 {
260 	struct fetch_connect *conn;
261 #if defined(SO_NOSIGPIPE) || defined(TCP_NOPUSH)
262 	int opt = 1;
263 #endif
264 
265 	if ((conn = calloc(1, sizeof(*conn))) == NULL)
266 		return NULL;
267 
268 	conn->sd = sd;
269 	conn->issock = 1;
270 	fcntl(sd, F_SETFD, FD_CLOEXEC);
271 #ifdef SO_NOSIGPIPE
272 	setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
273 #endif
274 #ifdef TCP_NOPUSH
275 	setsockopt(sd, IPPROTO_TCP, TCP_NOPUSH, &opt, sizeof(opt));
276 #endif
277 	return conn;
278 }
279 
280 int
281 fetch_close(struct fetch_connect *conn)
282 {
283 	if (conn == NULL)
284 		return 0;
285 
286 	fetch_flush(conn);
287 #ifdef WITH_SSL
288 	SSL_free(conn->ssl);
289 #endif
290 	close(conn->sd);
291 	free(conn->cache.buf);
292 	free(conn->buf);
293 	free(conn);
294 	return 0;
295 }
296 
297 #define FETCH_WRITE_WAIT	-3
298 #define FETCH_READ_WAIT		-2
299 #define FETCH_READ_ERROR	-1
300 
301 #ifdef WITH_SSL
302 static ssize_t
303 fetch_ssl_read(SSL *ssl, void *buf, size_t len)
304 {
305 	int rlen;
306 	rlen = SSL_read(ssl, buf, (int)len);
307 	if (rlen >= 0)
308 		return rlen;
309 
310 	switch (SSL_get_error(ssl, rlen)) {
311 	case SSL_ERROR_WANT_READ:
312 		return FETCH_READ_WAIT;
313 	case SSL_ERROR_WANT_WRITE:
314 		return FETCH_WRITE_WAIT;
315 	default:
316 		ERR_print_errors_fp(ttyout);
317 		return FETCH_READ_ERROR;
318 	}
319 }
320 #endif /* WITH_SSL */
321 
322 static ssize_t
323 fetch_nonssl_read(int sd, void *buf, size_t len)
324 {
325 	ssize_t rlen;
326 
327 	rlen = read(sd, buf, len);
328 	if (rlen == -1) {
329 		if (errno == EINTR || errno == EAGAIN)
330 			return FETCH_READ_WAIT;
331 		return FETCH_READ_ERROR;
332 	}
333 	return rlen;
334 }
335 
336 /*
337  * Cache some data that was read from a socket but cannot be immediately
338  * returned because of an interrupted system call.
339  */
340 static int
341 fetch_cache_data(struct fetch_connect *conn, char *src, size_t nbytes)
342 {
343 
344 	if (conn->cache.size < nbytes) {
345 		char *tmp = realloc(conn->cache.buf, nbytes);
346 		if (tmp == NULL)
347 			return -1;
348 
349 		conn->cache.buf = tmp;
350 		conn->cache.size = nbytes;
351 	}
352 
353 	memcpy(conn->cache.buf, src, nbytes);
354 	conn->cache.len = nbytes;
355 	conn->cache.pos = 0;
356 	return 0;
357 }
358 
359 static int
360 fetch_wait(struct fetch_connect *conn, ssize_t rlen, struct timeval *timeout)
361 {
362 	struct timeval now, delta;
363 	int fd = conn->sd;
364 	int rv, timeout_secs;
365 	struct pollfd pfd[1];
366 
367 	pfd[0].fd = fd;
368 	if (rlen == FETCH_READ_WAIT) {
369 		pfd[0].events = POLLIN;
370 	} else if (rlen == FETCH_WRITE_WAIT) {
371 		pfd[0].events = POLLOUT;
372 	} else {
373 		pfd[0].events = 0;
374 	}
375 
376 	do {
377 		if (quit_time > 0) {
378 			gettimeofday(&now, NULL);
379 			timersub(timeout, &now, &delta);
380 			timeout_secs = (int)(delta.tv_sec * 1000
381 			    + delta.tv_usec / 1000);
382 			if (timeout_secs < 0)
383 				timeout_secs = 0;
384 		} else {
385 			timeout_secs = INFTIM;
386 		}
387 		errno = 0;
388 		rv = ftp_poll(pfd, 1, timeout_secs);
389 				/* loop until poll !EINTR && !EAGAIN */
390 	} while (rv == -1 && (errno == EINTR || errno == EAGAIN));
391 	if (rv == 0) {		/* poll timeout */
392 		fprintf(ttyout, "\r\n%s: transfer aborted"
393 		    " because stalled for %lu sec.\r\n",
394 		    getprogname(), (unsigned long)quit_time);
395 		errno = ETIMEDOUT;
396 		conn->iserr = ETIMEDOUT;
397 		return -1;
398 	}
399 	if (rv == -1) {		/* poll error */
400 		conn->iserr = errno;
401 		return -1;
402 	}
403 	return 0;
404 }
405 
406 size_t
407 fetch_read(void *ptr, size_t size, size_t nmemb, struct fetch_connect *conn)
408 {
409 	ssize_t rlen, total;
410 	size_t len;
411 	char *start, *buf;
412 	struct timeval timeout;
413 
414 	if (quit_time > 0) {
415 		gettimeofday(&timeout, NULL);
416 		timeout.tv_sec += quit_time;
417 	}
418 
419 	total = 0;
420 	start = buf = ptr;
421 	len = size * nmemb;
422 
423 	if (conn->cache.len > 0) {
424 		/*
425 		 * The last invocation of fetch_read was interrupted by a
426 		 * signal after some data had been read from the socket. Copy
427 		 * the cached data into the supplied buffer before trying to
428 		 * read from the socket again.
429 		 */
430 		total = (conn->cache.len < len) ? conn->cache.len : len;
431 		memcpy(buf, conn->cache.buf, total);
432 
433 		conn->cache.len -= total;
434 		conn->cache.pos += total;
435 		len -= total;
436 		buf += total;
437 	}
438 
439 	while (len > 0) {
440 		/*
441 		 * The socket is non-blocking.  Instead of the canonical
442 		 * poll() -> read(), we do the following:
443 		 *
444 		 * 1) call read() or SSL_read().
445 		 * 2) if an error occurred, return -1.
446 		 * 3) if we received data but we still expect more,
447 		 *    update our counters and loop.
448 		 * 4) if read() or SSL_read() signaled EOF, return.
449 		 * 5) if we did not receive any data but we're not at EOF,
450 		 *    call poll().
451 		 *
452 		 * In the SSL case, this is necessary because if we
453 		 * receive a close notification, we have to call
454 		 * SSL_read() one additional time after we've read
455 		 * everything we received.
456 		 *
457 		 * In the non-SSL case, it may improve performance (very
458 		 * slightly) when reading small amounts of data.
459 		 */
460 #ifdef WITH_SSL
461 		if (conn->ssl != NULL)
462 			rlen = fetch_ssl_read(conn->ssl, buf, len);
463 		else
464 #endif
465 			rlen = fetch_nonssl_read(conn->sd, buf, len);
466 		switch (rlen) {
467 		case 0:
468 			conn->iseof = 1;
469 			return total;
470 		case FETCH_READ_ERROR:
471 			conn->iserr = errno;
472 			if (errno == EINTR || errno == EAGAIN)
473 				fetch_cache_data(conn, start, total);
474 			return 0;
475 		case FETCH_READ_WAIT:
476 		case FETCH_WRITE_WAIT:
477 			if (fetch_wait(conn, rlen, &timeout) == -1)
478 				return 0;
479 			break;
480 		default:
481 			len -= rlen;
482 			buf += rlen;
483 			total += rlen;
484 			break;
485 		}
486 	}
487 	return total;
488 }
489 
490 #define MIN_BUF_SIZE 1024
491 
492 /*
493  * Read a line of text from a connection w/ timeout
494  */
495 char *
496 fetch_getln(char *str, int size, struct fetch_connect *conn)
497 {
498 	size_t tmpsize;
499 	size_t len;
500 	char c;
501 
502 	if (conn->buf == NULL) {
503 		if ((conn->buf = malloc(MIN_BUF_SIZE)) == NULL) {
504 			errno = ENOMEM;
505 			conn->iserr = 1;
506 			return NULL;
507 		}
508 		conn->bufsize = MIN_BUF_SIZE;
509 	}
510 
511 	if (conn->iserr || conn->iseof)
512 		return NULL;
513 
514 	if (conn->buflen - conn->bufpos > 0)
515 		goto done;
516 
517 	conn->buf[0] = '\0';
518 	conn->bufpos = 0;
519 	conn->buflen = 0;
520 	do {
521 		len = fetch_read(&c, sizeof(c), 1, conn);
522 		if (len == 0) {
523 			if (conn->iserr)
524 				return NULL;
525 			if (conn->iseof)
526 				break;
527 			abort();
528 		}
529 		conn->buf[conn->buflen++] = c;
530 		if (conn->buflen == conn->bufsize) {
531 			char *tmp = conn->buf;
532 			tmpsize = conn->bufsize * 2 + 1;
533 			if ((tmp = realloc(tmp, tmpsize)) == NULL) {
534 				errno = ENOMEM;
535 				conn->iserr = 1;
536 				return NULL;
537 			}
538 			conn->buf = tmp;
539 			conn->bufsize = tmpsize;
540 		}
541 	} while (c != '\n');
542 
543 	if (conn->buflen == 0)
544 		return NULL;
545  done:
546 	tmpsize = MIN(size - 1, (int)(conn->buflen - conn->bufpos));
547 	memcpy(str, conn->buf + conn->bufpos, tmpsize);
548 	str[tmpsize] = '\0';
549 	conn->bufpos += tmpsize;
550 	return str;
551 }
552 
553 int
554 fetch_getline(struct fetch_connect *conn, char *buf, size_t buflen,
555     const char **errormsg)
556 {
557 	size_t len;
558 	int rv;
559 
560 	if (fetch_getln(buf, (int)buflen, conn) == NULL) {
561 		if (conn->iseof) {	/* EOF */
562 			rv = -2;
563 			if (errormsg)
564 				*errormsg = "\nEOF received";
565 		} else {		/* error */
566 			rv = -1;
567 			if (errormsg)
568 				*errormsg = "Error encountered";
569 		}
570 		fetch_clearerr(conn);
571 		return rv;
572 	}
573 	len = strlen(buf);
574 	if (buf[len - 1] == '\n') {	/* clear any trailing newline */
575 		buf[--len] = '\0';
576 	} else if (len == buflen - 1) {	/* line too long */
577 		for (;;) {
578 			char c;
579 			size_t rlen = fetch_read(&c, sizeof(c), 1, conn);
580 			if (rlen == 0 || c == '\n')
581 				break;
582 		}
583 		if (errormsg)
584 			*errormsg = "Input line is too long (specify -b > 16384)";
585 		fetch_clearerr(conn);
586 		return -3;
587 	}
588 	if (errormsg)
589 		*errormsg = NULL;
590 	return (int)len;
591 }
592 
593 #ifdef WITH_SSL
594 /*
595  * Start the SSL/TLS negotiation.
596  * Socket fcntl flags are temporarily updated to include O_NONBLOCK;
597  * these will not be reverted on connection failure.
598  * Returns pointer to allocated SSL structure on success,
599  * or NULL upon failure.
600  */
601 void *
602 fetch_start_ssl(int sock, const char *servername)
603 {
604 	SSL *ssl = NULL;
605 	SSL_CTX *ctx = NULL;
606 	X509_VERIFY_PARAM *param;
607 	int ret, ssl_err, flags, rv, timeout_secs;
608 	int verify = !ftp_truthy("sslnoverify", getoptionvalue("sslnoverify"), 0);
609 	struct timeval timeout, now, delta;
610 	struct pollfd pfd[1];
611 
612 	/* Init the SSL library and context */
613 	if (!SSL_library_init()){
614 		warnx("SSL library init failed");
615 		goto cleanup_start_ssl;
616 	}
617 
618 	SSL_load_error_strings();
619 
620 	ctx = SSL_CTX_new(SSLv23_client_method());
621 	SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
622 	if (verify) {
623 		SSL_CTX_set_default_verify_paths(ctx);
624 		SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
625 	}
626 
627 	ssl = SSL_new(ctx);
628 	if (ssl == NULL){
629 		warnx("SSL context creation failed");
630 		goto cleanup_start_ssl;
631 	}
632 
633 	if (verify) {
634 		param = SSL_get0_param(ssl);
635 		if (!X509_VERIFY_PARAM_set1_host(param, servername,
636 		    strlen(servername))) {
637 			warnx("SSL verification setup failed");
638 			goto cleanup_start_ssl;
639 		}
640 
641 		/* Enable peer verification, (using the default callback) */
642 		SSL_set_verify(ssl, SSL_VERIFY_PEER, NULL);
643 	}
644 #ifdef SSL_OP_IGNORE_UNEXPECTED_EOF
645 	SSL_set_options(ssl, SSL_OP_IGNORE_UNEXPECTED_EOF);
646 #endif
647 
648 						/* save current socket flags */
649 	if ((flags = fcntl(sock, F_GETFL, 0)) == -1) {
650 		warn("Can't %s socket flags for SSL connect to `%s'",
651 		    "save", servername);
652 		goto cleanup_start_ssl;
653 	}
654 						/* set non-blocking connect */
655 	if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) == -1) {
656 		warn("Can't set socket non-blocking for SSL connect to `%s'",
657 		    servername);
658 		goto cleanup_start_ssl;
659 	}
660 
661 	/* NOTE: we now must restore socket flags on successful connection */
662 
663 	(void)gettimeofday(&timeout, NULL);	/* setup SSL_connect() timeout */
664 	timeout.tv_sec += (quit_time > 0) ? quit_time: 60;
665 						/* without -q, default to 60s */
666 
667 	SSL_set_fd(ssl, sock);
668 	if (!SSL_set_tlsext_host_name(ssl, __UNCONST(servername))) {
669 		warnx("SSL hostname setting failed");
670 		goto cleanup_start_ssl;
671 	}
672 	pfd[0].fd = sock;
673 	pfd[0].events = 0;
674 	while ((ret = SSL_connect(ssl)) <= 0) {
675 		ssl_err = SSL_get_error(ssl, ret);
676 		DPRINTF("%s: SSL_connect() ret=%d ssl_err=%d\n",
677 		    __func__, ret, ssl_err);
678 		if (ret == 0) { /* unsuccessful handshake */
679 			ERR_print_errors_fp(ttyout);
680 			goto cleanup_start_ssl;
681 		}
682 		if (ssl_err == SSL_ERROR_WANT_READ) {
683 			pfd[0].events = POLLIN;
684 		} else if (ssl_err == SSL_ERROR_WANT_WRITE) {
685 			pfd[0].events = POLLOUT;
686 		} else {
687 			ERR_print_errors_fp(ttyout);
688 			goto cleanup_start_ssl;
689 		}
690 		(void)gettimeofday(&now, NULL);
691 		timersub(&timeout, &now, &delta);
692 		timeout_secs = (int)(delta.tv_sec * 1000
693 		    + delta.tv_usec / 1000);
694 		if (timeout_secs < 0)
695 			timeout_secs = 0;
696 		rv = ftp_poll(pfd, 1, timeout_secs);
697 		if (rv == 0) {		/* poll for SSL_connect() timed out */
698 			fprintf(ttyout, "Timeout establishing SSL connection to `%s'\n",
699 			    servername);
700 			goto cleanup_start_ssl;
701 		} else if (rv == -1 && errno != EINTR && errno != EAGAIN) {
702 			warn("Error polling for SSL connect to `%s'", servername);
703 			goto cleanup_start_ssl;
704 		}
705 	}
706 
707 	if (fcntl(sock, F_SETFL, flags) == -1) {
708 						/* restore socket flags */
709 		warn("Can't %s socket flags for SSL connect to `%s'",
710 		    "restore", servername);
711 		goto cleanup_start_ssl;
712 	}
713 
714 	if (ftp_debug && verbose) {
715 		X509 *cert;
716 		X509_NAME *name;
717 		char *str;
718 
719 		fprintf(ttyout, "SSL connection established using %s\n",
720 		    SSL_get_cipher(ssl));
721 		cert = SSL_get_peer_certificate(ssl);
722 		name = X509_get_subject_name(cert);
723 		str = X509_NAME_oneline(name, 0, 0);
724 		fprintf(ttyout, "Certificate subject: %s\n", str);
725 		free(str);
726 		name = X509_get_issuer_name(cert);
727 		str = X509_NAME_oneline(name, 0, 0);
728 		fprintf(ttyout, "Certificate issuer: %s\n", str);
729 		free(str);
730 	}
731 
732 	return ssl;
733 
734  cleanup_start_ssl:
735 	if (ssl)
736 		SSL_free(ssl);
737 	if (ctx)
738 		SSL_CTX_free(ctx);
739 	return NULL;
740 }
741 #endif /* WITH_SSL */
742 
743 
744 void
745 fetch_set_ssl(struct fetch_connect *conn, void *ssl)
746 {
747 #ifdef WITH_SSL
748 	conn->ssl = ssl;
749 #endif
750 }
751