xref: /freebsd/lib/libfetch/common.c (revision 4ec234c813eed05c166859bba82c882e40826eb9)
1 /*-
2  * Copyright (c) 1998-2011 Dag-Erling Smørgrav
3  * Copyright (c) 2013 Michael Gmelin <freebsd@grem.de>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer
11  *    in this position and unchanged.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include <sys/param.h>
34 #include <sys/socket.h>
35 #include <sys/time.h>
36 #include <sys/uio.h>
37 
38 #include <netinet/in.h>
39 
40 #include <ctype.h>
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <netdb.h>
44 #include <pwd.h>
45 #include <stdarg.h>
46 #include <stdlib.h>
47 #include <stdio.h>
48 #include <string.h>
49 #include <unistd.h>
50 
51 #ifdef WITH_SSL
52 #include <openssl/x509v3.h>
53 #endif
54 
55 #include "fetch.h"
56 #include "common.h"
57 
58 
59 /*** Local data **************************************************************/
60 
61 /*
62  * Error messages for resolver errors
63  */
64 static struct fetcherr netdb_errlist[] = {
65 #ifdef EAI_NODATA
66 	{ EAI_NODATA,	FETCH_RESOLV,	"Host not found" },
67 #endif
68 	{ EAI_AGAIN,	FETCH_TEMP,	"Transient resolver failure" },
69 	{ EAI_FAIL,	FETCH_RESOLV,	"Non-recoverable resolver failure" },
70 	{ EAI_NONAME,	FETCH_RESOLV,	"No address record" },
71 	{ -1,		FETCH_UNKNOWN,	"Unknown resolver error" }
72 };
73 
74 /* End-of-Line */
75 static const char ENDL[2] = "\r\n";
76 
77 
78 /*** Error-reporting functions ***********************************************/
79 
80 /*
81  * Map error code to string
82  */
83 static struct fetcherr *
84 fetch_finderr(struct fetcherr *p, int e)
85 {
86 	while (p->num != -1 && p->num != e)
87 		p++;
88 	return (p);
89 }
90 
91 /*
92  * Set error code
93  */
94 void
95 fetch_seterr(struct fetcherr *p, int e)
96 {
97 	p = fetch_finderr(p, e);
98 	fetchLastErrCode = p->cat;
99 	snprintf(fetchLastErrString, MAXERRSTRING, "%s", p->string);
100 }
101 
102 /*
103  * Set error code according to errno
104  */
105 void
106 fetch_syserr(void)
107 {
108 	switch (errno) {
109 	case 0:
110 		fetchLastErrCode = FETCH_OK;
111 		break;
112 	case EPERM:
113 	case EACCES:
114 	case EROFS:
115 	case EAUTH:
116 	case ENEEDAUTH:
117 		fetchLastErrCode = FETCH_AUTH;
118 		break;
119 	case ENOENT:
120 	case EISDIR: /* XXX */
121 		fetchLastErrCode = FETCH_UNAVAIL;
122 		break;
123 	case ENOMEM:
124 		fetchLastErrCode = FETCH_MEMORY;
125 		break;
126 	case EBUSY:
127 	case EAGAIN:
128 		fetchLastErrCode = FETCH_TEMP;
129 		break;
130 	case EEXIST:
131 		fetchLastErrCode = FETCH_EXISTS;
132 		break;
133 	case ENOSPC:
134 		fetchLastErrCode = FETCH_FULL;
135 		break;
136 	case EADDRINUSE:
137 	case EADDRNOTAVAIL:
138 	case ENETDOWN:
139 	case ENETUNREACH:
140 	case ENETRESET:
141 	case EHOSTUNREACH:
142 		fetchLastErrCode = FETCH_NETWORK;
143 		break;
144 	case ECONNABORTED:
145 	case ECONNRESET:
146 		fetchLastErrCode = FETCH_ABORT;
147 		break;
148 	case ETIMEDOUT:
149 		fetchLastErrCode = FETCH_TIMEOUT;
150 		break;
151 	case ECONNREFUSED:
152 	case EHOSTDOWN:
153 		fetchLastErrCode = FETCH_DOWN;
154 		break;
155 default:
156 		fetchLastErrCode = FETCH_UNKNOWN;
157 	}
158 	snprintf(fetchLastErrString, MAXERRSTRING, "%s", strerror(errno));
159 }
160 
161 
162 /*
163  * Emit status message
164  */
165 void
166 fetch_info(const char *fmt, ...)
167 {
168 	va_list ap;
169 
170 	va_start(ap, fmt);
171 	vfprintf(stderr, fmt, ap);
172 	va_end(ap);
173 	fputc('\n', stderr);
174 }
175 
176 
177 /*** Network-related utility functions ***************************************/
178 
179 /*
180  * Return the default port for a scheme
181  */
182 int
183 fetch_default_port(const char *scheme)
184 {
185 	struct servent *se;
186 
187 	if ((se = getservbyname(scheme, "tcp")) != NULL)
188 		return (ntohs(se->s_port));
189 	if (strcasecmp(scheme, SCHEME_FTP) == 0)
190 		return (FTP_DEFAULT_PORT);
191 	if (strcasecmp(scheme, SCHEME_HTTP) == 0)
192 		return (HTTP_DEFAULT_PORT);
193 	return (0);
194 }
195 
196 /*
197  * Return the default proxy port for a scheme
198  */
199 int
200 fetch_default_proxy_port(const char *scheme)
201 {
202 	if (strcasecmp(scheme, SCHEME_FTP) == 0)
203 		return (FTP_DEFAULT_PROXY_PORT);
204 	if (strcasecmp(scheme, SCHEME_HTTP) == 0)
205 		return (HTTP_DEFAULT_PROXY_PORT);
206 	return (0);
207 }
208 
209 
210 /*
211  * Create a connection for an existing descriptor.
212  */
213 conn_t *
214 fetch_reopen(int sd)
215 {
216 	conn_t *conn;
217 	int opt = 1;
218 
219 	/* allocate and fill connection structure */
220 	if ((conn = calloc(1, sizeof(*conn))) == NULL)
221 		return (NULL);
222 	fcntl(sd, F_SETFD, FD_CLOEXEC);
223 	setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof opt);
224 	conn->sd = sd;
225 	++conn->ref;
226 	return (conn);
227 }
228 
229 
230 /*
231  * Bump a connection's reference count.
232  */
233 conn_t *
234 fetch_ref(conn_t *conn)
235 {
236 
237 	++conn->ref;
238 	return (conn);
239 }
240 
241 
242 /*
243  * Bind a socket to a specific local address
244  */
245 int
246 fetch_bind(int sd, int af, const char *addr)
247 {
248 	struct addrinfo hints, *res, *res0;
249 	int err;
250 
251 	memset(&hints, 0, sizeof(hints));
252 	hints.ai_family = af;
253 	hints.ai_socktype = SOCK_STREAM;
254 	hints.ai_protocol = 0;
255 	if ((err = getaddrinfo(addr, NULL, &hints, &res0)) != 0)
256 		return (-1);
257 	for (res = res0; res; res = res->ai_next)
258 		if (bind(sd, res->ai_addr, res->ai_addrlen) == 0)
259 			return (0);
260 	return (-1);
261 }
262 
263 
264 /*
265  * Establish a TCP connection to the specified port on the specified host.
266  */
267 conn_t *
268 fetch_connect(const char *host, int port, int af, int verbose)
269 {
270 	conn_t *conn;
271 	char pbuf[10];
272 	const char *bindaddr;
273 	struct addrinfo hints, *res, *res0;
274 	int sd, err;
275 
276 	DEBUG(fprintf(stderr, "---> %s:%d\n", host, port));
277 
278 	if (verbose)
279 		fetch_info("looking up %s", host);
280 
281 	/* look up host name and set up socket address structure */
282 	snprintf(pbuf, sizeof(pbuf), "%d", port);
283 	memset(&hints, 0, sizeof(hints));
284 	hints.ai_family = af;
285 	hints.ai_socktype = SOCK_STREAM;
286 	hints.ai_protocol = 0;
287 	if ((err = getaddrinfo(host, pbuf, &hints, &res0)) != 0) {
288 		netdb_seterr(err);
289 		return (NULL);
290 	}
291 	bindaddr = getenv("FETCH_BIND_ADDRESS");
292 
293 	if (verbose)
294 		fetch_info("connecting to %s:%d", host, port);
295 
296 	/* try to connect */
297 	for (sd = -1, res = res0; res; sd = -1, res = res->ai_next) {
298 		if ((sd = socket(res->ai_family, res->ai_socktype,
299 			 res->ai_protocol)) == -1)
300 			continue;
301 		if (bindaddr != NULL && *bindaddr != '\0' &&
302 		    fetch_bind(sd, res->ai_family, bindaddr) != 0) {
303 			fetch_info("failed to bind to '%s'", bindaddr);
304 			close(sd);
305 			continue;
306 		}
307 		if (connect(sd, res->ai_addr, res->ai_addrlen) == 0 &&
308 		    fcntl(sd, F_SETFL, O_NONBLOCK) == 0)
309 			break;
310 		close(sd);
311 	}
312 	freeaddrinfo(res0);
313 	if (sd == -1) {
314 		fetch_syserr();
315 		return (NULL);
316 	}
317 
318 	if ((conn = fetch_reopen(sd)) == NULL) {
319 		fetch_syserr();
320 		close(sd);
321 	}
322 	return (conn);
323 }
324 
325 #ifdef WITH_SSL
326 /*
327  * Convert characters A-Z to lowercase (intentionally avoid any locale
328  * specific conversions).
329  */
330 static char
331 fetch_ssl_tolower(char in)
332 {
333 	if (in >= 'A' && in <= 'Z')
334 		return (in + 32);
335 	else
336 		return (in);
337 }
338 
339 /*
340  * isalpha implementation that intentionally avoids any locale specific
341  * conversions.
342  */
343 static int
344 fetch_ssl_isalpha(char in)
345 {
346 	return ((in >= 'A' && in <= 'Z') || (in >= 'a' && in <= 'z'));
347 }
348 
349 /*
350  * Check if passed hostnames a and b are equal.
351  */
352 static int
353 fetch_ssl_hname_equal(const char *a, size_t alen, const char *b,
354     size_t blen)
355 {
356 	size_t i;
357 
358 	if (alen != blen)
359 		return (0);
360 	for (i = 0; i < alen; ++i) {
361 		if (fetch_ssl_tolower(a[i]) != fetch_ssl_tolower(b[i]))
362 			return (0);
363 	}
364 	return (1);
365 }
366 
367 /*
368  * Check if domain label is traditional, meaning that only A-Z, a-z, 0-9
369  * and '-' (hyphen) are allowed. Hyphens have to be surrounded by alpha-
370  * numeric characters. Double hyphens (like they're found in IDN a-labels
371  * 'xn--') are not allowed. Empty labels are invalid.
372  */
373 static int
374 fetch_ssl_is_trad_domain_label(const char *l, size_t len, int wcok)
375 {
376 	size_t i;
377 
378 	if (!len || l[0] == '-' || l[len-1] == '-')
379 		return (0);
380 	for (i = 0; i < len; ++i) {
381 		if (!isdigit(l[i]) &&
382 		    !fetch_ssl_isalpha(l[i]) &&
383 		    !(l[i] == '*' && wcok) &&
384 		    !(l[i] == '-' && l[i - 1] != '-'))
385 			return (0);
386 	}
387 	return (1);
388 }
389 
390 /*
391  * Check if host name consists only of numbers. This might indicate an IP
392  * address, which is not a good idea for CN wildcard comparison.
393  */
394 static int
395 fetch_ssl_hname_is_only_numbers(const char *hostname, size_t len)
396 {
397 	size_t i;
398 
399 	for (i = 0; i < len; ++i) {
400 		if (!((hostname[i] >= '0' && hostname[i] <= '9') ||
401 		    hostname[i] == '.'))
402 			return (0);
403 	}
404 	return (1);
405 }
406 
407 /*
408  * Check if the host name h passed matches the pattern passed in m which
409  * is usually part of subjectAltName or CN of a certificate presented to
410  * the client. This includes wildcard matching. The algorithm is based on
411  * RFC6125, sections 6.4.3 and 7.2, which clarifies RFC2818 and RFC3280.
412  */
413 static int
414 fetch_ssl_hname_match(const char *h, size_t hlen, const char *m,
415     size_t mlen)
416 {
417 	int delta, hdotidx, mdot1idx, wcidx;
418 	const char *hdot, *mdot1, *mdot2;
419 	const char *wc; /* wildcard */
420 
421 	if (!(h && *h && m && *m))
422 		return (0);
423 	if ((wc = strnstr(m, "*", mlen)) == NULL)
424 		return (fetch_ssl_hname_equal(h, hlen, m, mlen));
425 	wcidx = wc - m;
426 	/* hostname should not be just dots and numbers */
427 	if (fetch_ssl_hname_is_only_numbers(h, hlen))
428 		return (0);
429 	/* only one wildcard allowed in pattern */
430 	if (strnstr(wc + 1, "*", mlen - wcidx - 1) != NULL)
431 		return (0);
432 	/*
433 	 * there must be at least two more domain labels and
434 	 * wildcard has to be in the leftmost label (RFC6125)
435 	 */
436 	mdot1 = strnstr(m, ".", mlen);
437 	if (mdot1 == NULL || mdot1 < wc || (mlen - (mdot1 - m)) < 4)
438 		return (0);
439 	mdot1idx = mdot1 - m;
440 	mdot2 = strnstr(mdot1 + 1, ".", mlen - mdot1idx - 1);
441 	if (mdot2 == NULL || (mlen - (mdot2 - m)) < 2)
442 		return (0);
443 	/* hostname must contain a dot and not be the 1st char */
444 	hdot = strnstr(h, ".", hlen);
445 	if (hdot == NULL || hdot == h)
446 		return (0);
447 	hdotidx = hdot - h;
448 	/*
449 	 * host part of hostname must be at least as long as
450 	 * pattern it's supposed to match
451 	 */
452 	if (hdotidx < mdot1idx)
453 		return (0);
454 	/*
455 	 * don't allow wildcards in non-traditional domain names
456 	 * (IDN, A-label, U-label...)
457 	 */
458 	if (!fetch_ssl_is_trad_domain_label(h, hdotidx, 0) ||
459 	    !fetch_ssl_is_trad_domain_label(m, mdot1idx, 1))
460 		return (0);
461 	/* match domain part (part after first dot) */
462 	if (!fetch_ssl_hname_equal(hdot, hlen - hdotidx, mdot1,
463 	    mlen - mdot1idx))
464 		return (0);
465 	/* match part left of wildcard */
466 	if (!fetch_ssl_hname_equal(h, wcidx, m, wcidx))
467 		return (0);
468 	/* match part right of wildcard */
469 	delta = mdot1idx - wcidx - 1;
470 	if (!fetch_ssl_hname_equal(hdot - delta, delta,
471 	    mdot1 - delta, delta))
472 		return (0);
473 	/* all tests succeded, it's a match */
474 	return (1);
475 }
476 
477 /*
478  * Get numeric host address info - returns NULL if host was not an IP
479  * address. The caller is responsible for deallocation using
480  * freeaddrinfo(3).
481  */
482 static struct addrinfo *
483 fetch_ssl_get_numeric_addrinfo(const char *hostname, size_t len)
484 {
485 	struct addrinfo hints, *res;
486 	char *host;
487 
488 	host = (char *)malloc(len + 1);
489 	memcpy(host, hostname, len);
490 	host[len] = '\0';
491 	memset(&hints, 0, sizeof(hints));
492 	hints.ai_family = PF_UNSPEC;
493 	hints.ai_socktype = SOCK_STREAM;
494 	hints.ai_protocol = 0;
495 	hints.ai_flags = AI_NUMERICHOST;
496 	/* port is not relevant for this purpose */
497 	getaddrinfo(host, "443", &hints, &res);
498 	free(host);
499 	return res;
500 }
501 
502 /*
503  * Compare ip address in addrinfo with address passes.
504  */
505 static int
506 fetch_ssl_ipaddr_match_bin(const struct addrinfo *lhost, const char *rhost,
507     size_t rhostlen)
508 {
509 	const void *left;
510 
511 	if (lhost->ai_family == AF_INET && rhostlen == 4) {
512 		left = (void *)&((struct sockaddr_in*)(void *)
513 		    lhost->ai_addr)->sin_addr.s_addr;
514 #ifdef INET6
515 	} else if (lhost->ai_family == AF_INET6 && rhostlen == 16) {
516 		left = (void *)&((struct sockaddr_in6 *)(void *)
517 		    lhost->ai_addr)->sin6_addr;
518 #endif
519 	} else
520 		return (0);
521 	return (!memcmp(left, (const void *)rhost, rhostlen) ? 1 : 0);
522 }
523 
524 /*
525  * Compare ip address in addrinfo with host passed. If host is not an IP
526  * address, comparison will fail.
527  */
528 static int
529 fetch_ssl_ipaddr_match(const struct addrinfo *laddr, const char *r,
530     size_t rlen)
531 {
532 	struct addrinfo *raddr;
533 	int ret;
534 	char *rip;
535 
536 	ret = 0;
537 	if ((raddr = fetch_ssl_get_numeric_addrinfo(r, rlen)) == NULL)
538 		return 0; /* not a numeric host */
539 
540 	if (laddr->ai_family == raddr->ai_family) {
541 		if (laddr->ai_family == AF_INET) {
542 			rip = (char *)&((struct sockaddr_in *)(void *)
543 			    raddr->ai_addr)->sin_addr.s_addr;
544 			ret = fetch_ssl_ipaddr_match_bin(laddr, rip, 4);
545 #ifdef INET6
546 		} else if (laddr->ai_family == AF_INET6) {
547 			rip = (char *)&((struct sockaddr_in6 *)(void *)
548 			    raddr->ai_addr)->sin6_addr;
549 			ret = fetch_ssl_ipaddr_match_bin(laddr, rip, 16);
550 #endif
551 		}
552 
553 	}
554 	freeaddrinfo(raddr);
555 	return (ret);
556 }
557 
558 /*
559  * Verify server certificate by subjectAltName.
560  */
561 static int
562 fetch_ssl_verify_altname(STACK_OF(GENERAL_NAME) *altnames,
563     const char *host, struct addrinfo *ip)
564 {
565 	const GENERAL_NAME *name;
566 	size_t nslen;
567 	int i;
568 	const char *ns;
569 
570 	for (i = 0; i < sk_GENERAL_NAME_num(altnames); ++i) {
571 #if OPENSSL_VERSION_NUMBER < 0x10000000L
572 		/*
573 		 * This is a workaround, since the following line causes
574 		 * alignment issues in clang:
575 		 * name = sk_GENERAL_NAME_value(altnames, i);
576 		 * OpenSSL explicitly warns not to use those macros
577 		 * directly, but there isn't much choice (and there
578 		 * shouldn't be any ill side effects)
579 		 */
580 		name = (GENERAL_NAME *)SKM_sk_value(void, altnames, i);
581 #else
582 		name = sk_GENERAL_NAME_value(altnames, i);
583 #endif
584 		ns = (const char *)ASN1_STRING_data(name->d.ia5);
585 		nslen = (size_t)ASN1_STRING_length(name->d.ia5);
586 
587 		if (name->type == GEN_DNS && ip == NULL &&
588 		    fetch_ssl_hname_match(host, strlen(host), ns, nslen))
589 			return (1);
590 		else if (name->type == GEN_IPADD && ip != NULL &&
591 		    fetch_ssl_ipaddr_match_bin(ip, ns, nslen))
592 			return (1);
593 	}
594 	return (0);
595 }
596 
597 /*
598  * Verify server certificate by CN.
599  */
600 static int
601 fetch_ssl_verify_cn(X509_NAME *subject, const char *host,
602     struct addrinfo *ip)
603 {
604 	ASN1_STRING *namedata;
605 	X509_NAME_ENTRY *nameentry;
606 	int cnlen, lastpos, loc, ret;
607 	unsigned char *cn;
608 
609 	ret = 0;
610 	lastpos = -1;
611 	loc = -1;
612 	cn = NULL;
613 	/* get most specific CN (last entry in list) and compare */
614 	while ((lastpos = X509_NAME_get_index_by_NID(subject,
615 	    NID_commonName, lastpos)) != -1)
616 		loc = lastpos;
617 
618 	if (loc > -1) {
619 		nameentry = X509_NAME_get_entry(subject, loc);
620 		namedata = X509_NAME_ENTRY_get_data(nameentry);
621 		cnlen = ASN1_STRING_to_UTF8(&cn, namedata);
622 		if (ip == NULL &&
623 		    fetch_ssl_hname_match(host, strlen(host), cn, cnlen))
624 			ret = 1;
625 		else if (ip != NULL && fetch_ssl_ipaddr_match(ip, cn, cnlen))
626 			ret = 1;
627 		OPENSSL_free(cn);
628 	}
629 	return (ret);
630 }
631 
632 /*
633  * Verify that server certificate subjectAltName/CN matches
634  * hostname. First check, if there are alternative subject names. If yes,
635  * those have to match. Only if those don't exist it falls back to
636  * checking the subject's CN.
637  */
638 static int
639 fetch_ssl_verify_hname(X509 *cert, const char *host)
640 {
641 	struct addrinfo *ip;
642 	STACK_OF(GENERAL_NAME) *altnames;
643 	X509_NAME *subject;
644 	int ret;
645 
646 	ret = 0;
647 	ip = fetch_ssl_get_numeric_addrinfo(host, strlen(host));
648 	altnames = X509_get_ext_d2i(cert, NID_subject_alt_name,
649 	    NULL, NULL);
650 
651 	if (altnames != NULL) {
652 		ret = fetch_ssl_verify_altname(altnames, host, ip);
653 	} else {
654 		subject = X509_get_subject_name(cert);
655 		if (subject != NULL)
656 			ret = fetch_ssl_verify_cn(subject, host, ip);
657 	}
658 
659 	if (ip != NULL)
660 		freeaddrinfo(ip);
661 	if (altnames != NULL)
662 		GENERAL_NAMES_free(altnames);
663 	return (ret);
664 }
665 
666 /*
667  * Configure transport security layer based on environment.
668  */
669 static void
670 fetch_ssl_setup_transport_layer(SSL_CTX *ctx, int verbose)
671 {
672 	long ssl_ctx_options;
673 
674 	ssl_ctx_options = SSL_OP_ALL | SSL_OP_NO_TICKET;
675 	if (getenv("SSL_ALLOW_SSL2") == NULL)
676 		ssl_ctx_options |= SSL_OP_NO_SSLv2;
677 	if (getenv("SSL_NO_SSL3") != NULL)
678 		ssl_ctx_options |= SSL_OP_NO_SSLv3;
679 	if (getenv("SSL_NO_TLS1") != NULL)
680 		ssl_ctx_options |= SSL_OP_NO_TLSv1;
681 	if (verbose)
682 		fetch_info("SSL options: %x", ssl_ctx_options);
683 	SSL_CTX_set_options(ctx, ssl_ctx_options);
684 }
685 
686 
687 /*
688  * Configure peer verification based on environment.
689  */
690 static int
691 fetch_ssl_setup_peer_verification(SSL_CTX *ctx, int verbose)
692 {
693 	X509_LOOKUP *crl_lookup;
694 	X509_STORE *crl_store;
695 	const char *ca_cert_file, *ca_cert_path, *crl_file;
696 
697 	if (getenv("SSL_NO_VERIFY_PEER") == NULL) {
698 		ca_cert_file = getenv("SSL_CA_CERT_FILE") != NULL ?
699 		    getenv("SSL_CA_CERT_FILE") : "/etc/ssl/cert.pem";
700 		ca_cert_path = getenv("SSL_CA_CERT_PATH");
701 		if (verbose) {
702 			fetch_info("Peer verification enabled");
703 			if (ca_cert_file != NULL)
704 				fetch_info("Using CA cert file: %s",
705 				    ca_cert_file);
706 			if (ca_cert_path != NULL)
707 				fetch_info("Using CA cert path: %s",
708 				    ca_cert_path);
709 		}
710 		SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER,
711 		    fetch_ssl_cb_verify_crt);
712 		SSL_CTX_load_verify_locations(ctx, ca_cert_file,
713 		    ca_cert_path);
714 		if ((crl_file = getenv("SSL_CRL_FILE")) != NULL) {
715 			if (verbose)
716 				fetch_info("Using CRL file: %s", crl_file);
717 			crl_store = SSL_CTX_get_cert_store(ctx);
718 			crl_lookup = X509_STORE_add_lookup(crl_store,
719 			    X509_LOOKUP_file());
720 			if (crl_lookup == NULL ||
721 			    !X509_load_crl_file(crl_lookup, crl_file,
722 				X509_FILETYPE_PEM)) {
723 				fprintf(stderr,
724 				    "Could not load CRL file %s\n",
725 				    crl_file);
726 				return (0);
727 			}
728 			X509_STORE_set_flags(crl_store,
729 			    X509_V_FLAG_CRL_CHECK |
730 			    X509_V_FLAG_CRL_CHECK_ALL);
731 		}
732 	}
733 	return (1);
734 }
735 
736 /*
737  * Configure client certificate based on environment.
738  */
739 static int
740 fetch_ssl_setup_client_certificate(SSL_CTX *ctx, int verbose)
741 {
742 	const char *client_cert_file, *client_key_file;
743 
744 	if ((client_cert_file = getenv("SSL_CLIENT_CERT_FILE")) != NULL) {
745 		client_key_file = getenv("SSL_CLIENT_KEY_FILE") != NULL ?
746 		    getenv("SSL_CLIENT_KEY_FILE") : client_cert_file;
747 		if (verbose) {
748 			fetch_info("Using client cert file: %s",
749 			    client_cert_file);
750 			fetch_info("Using client key file: %s",
751 			    client_key_file);
752 		}
753 		if (SSL_CTX_use_certificate_chain_file(ctx,
754 			client_cert_file) != 1) {
755 			fprintf(stderr,
756 			    "Could not load client certificate %s\n",
757 			    client_cert_file);
758 			return (0);
759 		}
760 		if (SSL_CTX_use_PrivateKey_file(ctx, client_key_file,
761 			SSL_FILETYPE_PEM) != 1) {
762 			fprintf(stderr,
763 			    "Could not load client key %s\n",
764 			    client_key_file);
765 			return (0);
766 		}
767 	}
768 	return (1);
769 }
770 
771 /*
772  * Callback for SSL certificate verification, this is called on server
773  * cert verification. It takes no decision, but informs the user in case
774  * verification failed.
775  */
776 int
777 fetch_ssl_cb_verify_crt(int verified, X509_STORE_CTX *ctx)
778 {
779 	X509 *crt;
780 	X509_NAME *name;
781 	char *str;
782 
783 	str = NULL;
784 	if (!verified) {
785 		if ((crt = X509_STORE_CTX_get_current_cert(ctx)) != NULL &&
786 		    (name = X509_get_subject_name(crt)) != NULL)
787 			str = X509_NAME_oneline(name, 0, 0);
788 		fprintf(stderr, "Certificate verification failed for %s\n",
789 		    str != NULL ? str : "no relevant certificate");
790 		OPENSSL_free(str);
791 	}
792 	return (verified);
793 }
794 
795 #endif
796 
797 /*
798  * Enable SSL on a connection.
799  */
800 int
801 fetch_ssl(conn_t *conn, const struct url *URL, int verbose)
802 {
803 #ifdef WITH_SSL
804 	int ret, ssl_err;
805 	X509_NAME *name;
806 	char *str;
807 
808 	/* Init the SSL library and context */
809 	if (!SSL_library_init()){
810 		fprintf(stderr, "SSL library init failed\n");
811 		return (-1);
812 	}
813 
814 	SSL_load_error_strings();
815 
816 	conn->ssl_meth = SSLv23_client_method();
817 	conn->ssl_ctx = SSL_CTX_new(conn->ssl_meth);
818 	SSL_CTX_set_mode(conn->ssl_ctx, SSL_MODE_AUTO_RETRY);
819 
820 	fetch_ssl_setup_transport_layer(conn->ssl_ctx, verbose);
821 	if (!fetch_ssl_setup_peer_verification(conn->ssl_ctx, verbose))
822 		return (-1);
823 	if (!fetch_ssl_setup_client_certificate(conn->ssl_ctx, verbose))
824 		return (-1);
825 
826 	conn->ssl = SSL_new(conn->ssl_ctx);
827 	if (conn->ssl == NULL) {
828 		fprintf(stderr, "SSL context creation failed\n");
829 		return (-1);
830 	}
831 	SSL_set_fd(conn->ssl, conn->sd);
832 
833 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
834 	if (!SSL_set_tlsext_host_name(conn->ssl,
835 	    __DECONST(struct url *, URL)->host)) {
836 		fprintf(stderr,
837 		    "TLS server name indication extension failed for host %s\n",
838 		    URL->host);
839 		return (-1);
840 	}
841 #endif
842 	while ((ret = SSL_connect(conn->ssl)) == -1) {
843 		ssl_err = SSL_get_error(conn->ssl, ret);
844 		if (ssl_err != SSL_ERROR_WANT_READ &&
845 		    ssl_err != SSL_ERROR_WANT_WRITE) {
846 			ERR_print_errors_fp(stderr);
847 			return (-1);
848 		}
849 	}
850 	conn->ssl_cert = SSL_get_peer_certificate(conn->ssl);
851 
852 	if (conn->ssl_cert == NULL) {
853 		fprintf(stderr, "No server SSL certificate\n");
854 		return (-1);
855 	}
856 
857 	if (getenv("SSL_NO_VERIFY_HOSTNAME") == NULL) {
858 		if (verbose)
859 			fetch_info("Verify hostname");
860 		if (!fetch_ssl_verify_hname(conn->ssl_cert, URL->host)) {
861 			fprintf(stderr,
862 			    "SSL certificate subject doesn't match host %s\n",
863 			    URL->host);
864 			return (-1);
865 		}
866 	}
867 
868 	if (verbose) {
869 		fetch_info("SSL connection established using %s",
870 		    SSL_get_cipher(conn->ssl));
871 		name = X509_get_subject_name(conn->ssl_cert);
872 		str = X509_NAME_oneline(name, 0, 0);
873 		fetch_info("Certificate subject: %s", str);
874 		OPENSSL_free(str);
875 		name = X509_get_issuer_name(conn->ssl_cert);
876 		str = X509_NAME_oneline(name, 0, 0);
877 		fetch_info("Certificate issuer: %s", str);
878 		OPENSSL_free(str);
879 	}
880 
881 	return (0);
882 #else
883 	(void)conn;
884 	(void)verbose;
885 	fprintf(stderr, "SSL support disabled\n");
886 	return (-1);
887 #endif
888 }
889 
890 #define FETCH_READ_WAIT		-2
891 #define FETCH_READ_ERROR	-1
892 #define FETCH_READ_DONE		 0
893 
894 #ifdef WITH_SSL
895 static ssize_t
896 fetch_ssl_read(SSL *ssl, char *buf, size_t len)
897 {
898 	ssize_t rlen;
899 	int ssl_err;
900 
901 	rlen = SSL_read(ssl, buf, len);
902 	if (rlen < 0) {
903 		ssl_err = SSL_get_error(ssl, rlen);
904 		if (ssl_err == SSL_ERROR_WANT_READ ||
905 		    ssl_err == SSL_ERROR_WANT_WRITE) {
906 			return (FETCH_READ_WAIT);
907 		} else {
908 			ERR_print_errors_fp(stderr);
909 			return (FETCH_READ_ERROR);
910 		}
911 	}
912 	return (rlen);
913 }
914 #endif
915 
916 /*
917  * Cache some data that was read from a socket but cannot be immediately
918  * returned because of an interrupted system call.
919  */
920 static int
921 fetch_cache_data(conn_t *conn, char *src, size_t nbytes)
922 {
923 	char *tmp;
924 
925 	if (conn->cache.size < nbytes) {
926 		tmp = realloc(conn->cache.buf, nbytes);
927 		if (tmp == NULL) {
928 			fetch_syserr();
929 			return (-1);
930 		}
931 		conn->cache.buf = tmp;
932 		conn->cache.size = nbytes;
933 	}
934 
935 	memcpy(conn->cache.buf, src, nbytes);
936 	conn->cache.len = nbytes;
937 	conn->cache.pos = 0;
938 
939 	return (0);
940 }
941 
942 
943 static ssize_t
944 fetch_socket_read(int sd, char *buf, size_t len)
945 {
946 	ssize_t rlen;
947 
948 	rlen = read(sd, buf, len);
949 	if (rlen < 0) {
950 		if (errno == EAGAIN || (errno == EINTR && fetchRestartCalls))
951 			return (FETCH_READ_WAIT);
952 		else
953 			return (FETCH_READ_ERROR);
954 	}
955 	return (rlen);
956 }
957 
958 /*
959  * Read a character from a connection w/ timeout
960  */
961 ssize_t
962 fetch_read(conn_t *conn, char *buf, size_t len)
963 {
964 	struct timeval now, timeout, delta;
965 	fd_set readfds;
966 	ssize_t rlen, total;
967 	char *start;
968 
969 	if (fetchTimeout > 0) {
970 		gettimeofday(&timeout, NULL);
971 		timeout.tv_sec += fetchTimeout;
972 	}
973 
974 	total = 0;
975 	start = buf;
976 
977 	if (conn->cache.len > 0) {
978 		/*
979 		 * The last invocation of fetch_read was interrupted by a
980 		 * signal after some data had been read from the socket. Copy
981 		 * the cached data into the supplied buffer before trying to
982 		 * read from the socket again.
983 		 */
984 		total = (conn->cache.len < len) ? conn->cache.len : len;
985 		memcpy(buf, conn->cache.buf, total);
986 
987 		conn->cache.len -= total;
988 		conn->cache.pos += total;
989 		len -= total;
990 		buf += total;
991 	}
992 
993 	while (len > 0) {
994 		/*
995 		 * The socket is non-blocking.  Instead of the canonical
996 		 * select() -> read(), we do the following:
997 		 *
998 		 * 1) call read() or SSL_read().
999 		 * 2) if an error occurred, return -1.
1000 		 * 3) if we received data but we still expect more,
1001 		 *    update our counters and loop.
1002 		 * 4) if read() or SSL_read() signaled EOF, return.
1003 		 * 5) if we did not receive any data but we're not at EOF,
1004 		 *    call select().
1005 		 *
1006 		 * In the SSL case, this is necessary because if we
1007 		 * receive a close notification, we have to call
1008 		 * SSL_read() one additional time after we've read
1009 		 * everything we received.
1010 		 *
1011 		 * In the non-SSL case, it may improve performance (very
1012 		 * slightly) when reading small amounts of data.
1013 		 */
1014 #ifdef WITH_SSL
1015 		if (conn->ssl != NULL)
1016 			rlen = fetch_ssl_read(conn->ssl, buf, len);
1017 		else
1018 #endif
1019 			rlen = fetch_socket_read(conn->sd, buf, len);
1020 		if (rlen == 0) {
1021 			break;
1022 		} else if (rlen > 0) {
1023 			len -= rlen;
1024 			buf += rlen;
1025 			total += rlen;
1026 			continue;
1027 		} else if (rlen == FETCH_READ_ERROR) {
1028 			if (errno == EINTR)
1029 				fetch_cache_data(conn, start, total);
1030 			return (-1);
1031 		}
1032 		// assert(rlen == FETCH_READ_WAIT);
1033 		FD_ZERO(&readfds);
1034 		while (!FD_ISSET(conn->sd, &readfds)) {
1035 			FD_SET(conn->sd, &readfds);
1036 			if (fetchTimeout > 0) {
1037 				gettimeofday(&now, NULL);
1038 				if (!timercmp(&timeout, &now, >)) {
1039 					errno = ETIMEDOUT;
1040 					fetch_syserr();
1041 					return (-1);
1042 				}
1043 				timersub(&timeout, &now, &delta);
1044 			}
1045 			errno = 0;
1046 			if (select(conn->sd + 1, &readfds, NULL, NULL,
1047 				fetchTimeout > 0 ? &delta : NULL) < 0) {
1048 				if (errno == EINTR) {
1049 					if (fetchRestartCalls)
1050 						continue;
1051 					/* Save anything that was read. */
1052 					fetch_cache_data(conn, start, total);
1053 				}
1054 				fetch_syserr();
1055 				return (-1);
1056 			}
1057 		}
1058 	}
1059 	return (total);
1060 }
1061 
1062 
1063 /*
1064  * Read a line of text from a connection w/ timeout
1065  */
1066 #define MIN_BUF_SIZE 1024
1067 
1068 int
1069 fetch_getln(conn_t *conn)
1070 {
1071 	char *tmp;
1072 	size_t tmpsize;
1073 	ssize_t len;
1074 	char c;
1075 
1076 	if (conn->buf == NULL) {
1077 		if ((conn->buf = malloc(MIN_BUF_SIZE)) == NULL) {
1078 			errno = ENOMEM;
1079 			return (-1);
1080 		}
1081 		conn->bufsize = MIN_BUF_SIZE;
1082 	}
1083 
1084 	conn->buf[0] = '\0';
1085 	conn->buflen = 0;
1086 
1087 	do {
1088 		len = fetch_read(conn, &c, 1);
1089 		if (len == -1)
1090 			return (-1);
1091 		if (len == 0)
1092 			break;
1093 		conn->buf[conn->buflen++] = c;
1094 		if (conn->buflen == conn->bufsize) {
1095 			tmp = conn->buf;
1096 			tmpsize = conn->bufsize * 2 + 1;
1097 			if ((tmp = realloc(tmp, tmpsize)) == NULL) {
1098 				errno = ENOMEM;
1099 				return (-1);
1100 			}
1101 			conn->buf = tmp;
1102 			conn->bufsize = tmpsize;
1103 		}
1104 	} while (c != '\n');
1105 
1106 	conn->buf[conn->buflen] = '\0';
1107 	DEBUG(fprintf(stderr, "<<< %s", conn->buf));
1108 	return (0);
1109 }
1110 
1111 
1112 /*
1113  * Write to a connection w/ timeout
1114  */
1115 ssize_t
1116 fetch_write(conn_t *conn, const char *buf, size_t len)
1117 {
1118 	struct iovec iov;
1119 
1120 	iov.iov_base = __DECONST(char *, buf);
1121 	iov.iov_len = len;
1122 	return fetch_writev(conn, &iov, 1);
1123 }
1124 
1125 /*
1126  * Write a vector to a connection w/ timeout
1127  * Note: can modify the iovec.
1128  */
1129 ssize_t
1130 fetch_writev(conn_t *conn, struct iovec *iov, int iovcnt)
1131 {
1132 	struct timeval now, timeout, delta;
1133 	fd_set writefds;
1134 	ssize_t wlen, total;
1135 	int r;
1136 
1137 	if (fetchTimeout) {
1138 		FD_ZERO(&writefds);
1139 		gettimeofday(&timeout, NULL);
1140 		timeout.tv_sec += fetchTimeout;
1141 	}
1142 
1143 	total = 0;
1144 	while (iovcnt > 0) {
1145 		while (fetchTimeout && !FD_ISSET(conn->sd, &writefds)) {
1146 			FD_SET(conn->sd, &writefds);
1147 			gettimeofday(&now, NULL);
1148 			delta.tv_sec = timeout.tv_sec - now.tv_sec;
1149 			delta.tv_usec = timeout.tv_usec - now.tv_usec;
1150 			if (delta.tv_usec < 0) {
1151 				delta.tv_usec += 1000000;
1152 				delta.tv_sec--;
1153 			}
1154 			if (delta.tv_sec < 0) {
1155 				errno = ETIMEDOUT;
1156 				fetch_syserr();
1157 				return (-1);
1158 			}
1159 			errno = 0;
1160 			r = select(conn->sd + 1, NULL, &writefds, NULL, &delta);
1161 			if (r == -1) {
1162 				if (errno == EINTR && fetchRestartCalls)
1163 					continue;
1164 				return (-1);
1165 			}
1166 		}
1167 		errno = 0;
1168 #ifdef WITH_SSL
1169 		if (conn->ssl != NULL)
1170 			wlen = SSL_write(conn->ssl,
1171 			    iov->iov_base, iov->iov_len);
1172 		else
1173 #endif
1174 			wlen = writev(conn->sd, iov, iovcnt);
1175 		if (wlen == 0) {
1176 			/* we consider a short write a failure */
1177 			/* XXX perhaps we shouldn't in the SSL case */
1178 			errno = EPIPE;
1179 			fetch_syserr();
1180 			return (-1);
1181 		}
1182 		if (wlen < 0) {
1183 			if (errno == EINTR && fetchRestartCalls)
1184 				continue;
1185 			return (-1);
1186 		}
1187 		total += wlen;
1188 		while (iovcnt > 0 && wlen >= (ssize_t)iov->iov_len) {
1189 			wlen -= iov->iov_len;
1190 			iov++;
1191 			iovcnt--;
1192 		}
1193 		if (iovcnt > 0) {
1194 			iov->iov_len -= wlen;
1195 			iov->iov_base = __DECONST(char *, iov->iov_base) + wlen;
1196 		}
1197 	}
1198 	return (total);
1199 }
1200 
1201 
1202 /*
1203  * Write a line of text to a connection w/ timeout
1204  */
1205 int
1206 fetch_putln(conn_t *conn, const char *str, size_t len)
1207 {
1208 	struct iovec iov[2];
1209 	int ret;
1210 
1211 	DEBUG(fprintf(stderr, ">>> %s\n", str));
1212 	iov[0].iov_base = __DECONST(char *, str);
1213 	iov[0].iov_len = len;
1214 	iov[1].iov_base = __DECONST(char *, ENDL);
1215 	iov[1].iov_len = sizeof(ENDL);
1216 	if (len == 0)
1217 		ret = fetch_writev(conn, &iov[1], 1);
1218 	else
1219 		ret = fetch_writev(conn, iov, 2);
1220 	if (ret == -1)
1221 		return (-1);
1222 	return (0);
1223 }
1224 
1225 
1226 /*
1227  * Close connection
1228  */
1229 int
1230 fetch_close(conn_t *conn)
1231 {
1232 	int ret;
1233 
1234 	if (--conn->ref > 0)
1235 		return (0);
1236 #ifdef WITH_SSL
1237 	if (conn->ssl) {
1238 		SSL_shutdown(conn->ssl);
1239 		SSL_set_connect_state(conn->ssl);
1240 		SSL_free(conn->ssl);
1241 		conn->ssl = NULL;
1242 	}
1243 	if (conn->ssl_ctx) {
1244 		SSL_CTX_free(conn->ssl_ctx);
1245 		conn->ssl_ctx = NULL;
1246 	}
1247 	if (conn->ssl_cert) {
1248 		X509_free(conn->ssl_cert);
1249 		conn->ssl_cert = NULL;
1250 	}
1251 #endif
1252 	ret = close(conn->sd);
1253 	free(conn->cache.buf);
1254 	free(conn->buf);
1255 	free(conn);
1256 	return (ret);
1257 }
1258 
1259 
1260 /*** Directory-related utility functions *************************************/
1261 
1262 int
1263 fetch_add_entry(struct url_ent **p, int *size, int *len,
1264     const char *name, struct url_stat *us)
1265 {
1266 	struct url_ent *tmp;
1267 
1268 	if (*p == NULL) {
1269 		*size = 0;
1270 		*len = 0;
1271 	}
1272 
1273 	if (*len >= *size - 1) {
1274 		tmp = realloc(*p, (*size * 2 + 1) * sizeof(**p));
1275 		if (tmp == NULL) {
1276 			errno = ENOMEM;
1277 			fetch_syserr();
1278 			return (-1);
1279 		}
1280 		*size = (*size * 2 + 1);
1281 		*p = tmp;
1282 	}
1283 
1284 	tmp = *p + *len;
1285 	snprintf(tmp->name, PATH_MAX, "%s", name);
1286 	memcpy(&tmp->stat, us, sizeof(*us));
1287 
1288 	(*len)++;
1289 	(++tmp)->name[0] = 0;
1290 
1291 	return (0);
1292 }
1293 
1294 
1295 /*** Authentication-related utility functions ********************************/
1296 
1297 static const char *
1298 fetch_read_word(FILE *f)
1299 {
1300 	static char word[1024];
1301 
1302 	if (fscanf(f, " %1023s ", word) != 1)
1303 		return (NULL);
1304 	return (word);
1305 }
1306 
1307 /*
1308  * Get authentication data for a URL from .netrc
1309  */
1310 int
1311 fetch_netrc_auth(struct url *url)
1312 {
1313 	char fn[PATH_MAX];
1314 	const char *word;
1315 	char *p;
1316 	FILE *f;
1317 
1318 	if ((p = getenv("NETRC")) != NULL) {
1319 		if (snprintf(fn, sizeof(fn), "%s", p) >= (int)sizeof(fn)) {
1320 			fetch_info("$NETRC specifies a file name "
1321 			    "longer than PATH_MAX");
1322 			return (-1);
1323 		}
1324 	} else {
1325 		if ((p = getenv("HOME")) != NULL) {
1326 			struct passwd *pwd;
1327 
1328 			if ((pwd = getpwuid(getuid())) == NULL ||
1329 			    (p = pwd->pw_dir) == NULL)
1330 				return (-1);
1331 		}
1332 		if (snprintf(fn, sizeof(fn), "%s/.netrc", p) >= (int)sizeof(fn))
1333 			return (-1);
1334 	}
1335 
1336 	if ((f = fopen(fn, "r")) == NULL)
1337 		return (-1);
1338 	while ((word = fetch_read_word(f)) != NULL) {
1339 		if (strcmp(word, "default") == 0) {
1340 			DEBUG(fetch_info("Using default .netrc settings"));
1341 			break;
1342 		}
1343 		if (strcmp(word, "machine") == 0 &&
1344 		    (word = fetch_read_word(f)) != NULL &&
1345 		    strcasecmp(word, url->host) == 0) {
1346 			DEBUG(fetch_info("Using .netrc settings for %s", word));
1347 			break;
1348 		}
1349 	}
1350 	if (word == NULL)
1351 		goto ferr;
1352 	while ((word = fetch_read_word(f)) != NULL) {
1353 		if (strcmp(word, "login") == 0) {
1354 			if ((word = fetch_read_word(f)) == NULL)
1355 				goto ferr;
1356 			if (snprintf(url->user, sizeof(url->user),
1357 				"%s", word) > (int)sizeof(url->user)) {
1358 				fetch_info("login name in .netrc is too long");
1359 				url->user[0] = '\0';
1360 			}
1361 		} else if (strcmp(word, "password") == 0) {
1362 			if ((word = fetch_read_word(f)) == NULL)
1363 				goto ferr;
1364 			if (snprintf(url->pwd, sizeof(url->pwd),
1365 				"%s", word) > (int)sizeof(url->pwd)) {
1366 				fetch_info("password in .netrc is too long");
1367 				url->pwd[0] = '\0';
1368 			}
1369 		} else if (strcmp(word, "account") == 0) {
1370 			if ((word = fetch_read_word(f)) == NULL)
1371 				goto ferr;
1372 			/* XXX not supported! */
1373 		} else {
1374 			break;
1375 		}
1376 	}
1377 	fclose(f);
1378 	return (0);
1379  ferr:
1380 	fclose(f);
1381 	return (-1);
1382 }
1383 
1384 /*
1385  * The no_proxy environment variable specifies a set of domains for
1386  * which the proxy should not be consulted; the contents is a comma-,
1387  * or space-separated list of domain names.  A single asterisk will
1388  * override all proxy variables and no transactions will be proxied
1389  * (for compatability with lynx and curl, see the discussion at
1390  * <http://curl.haxx.se/mail/archive_pre_oct_99/0009.html>).
1391  */
1392 int
1393 fetch_no_proxy_match(const char *host)
1394 {
1395 	const char *no_proxy, *p, *q;
1396 	size_t h_len, d_len;
1397 
1398 	if ((no_proxy = getenv("NO_PROXY")) == NULL &&
1399 	    (no_proxy = getenv("no_proxy")) == NULL)
1400 		return (0);
1401 
1402 	/* asterisk matches any hostname */
1403 	if (strcmp(no_proxy, "*") == 0)
1404 		return (1);
1405 
1406 	h_len = strlen(host);
1407 	p = no_proxy;
1408 	do {
1409 		/* position p at the beginning of a domain suffix */
1410 		while (*p == ',' || isspace((unsigned char)*p))
1411 			p++;
1412 
1413 		/* position q at the first separator character */
1414 		for (q = p; *q; ++q)
1415 			if (*q == ',' || isspace((unsigned char)*q))
1416 				break;
1417 
1418 		d_len = q - p;
1419 		if (d_len > 0 && h_len >= d_len &&
1420 		    strncasecmp(host + h_len - d_len,
1421 			p, d_len) == 0) {
1422 			/* domain name matches */
1423 			return (1);
1424 		}
1425 
1426 		p = q + 1;
1427 	} while (*q);
1428 
1429 	return (0);
1430 }
1431