1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000-2005 Free Software Foundation, Inc.
3 Originally contributed by Christian Fraenkel.
5 This file is part of GNU Wget.
7 GNU Wget is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 GNU Wget is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with Wget; if not, write to the Free Software Foundation, Inc.,
19 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 In addition, as a special exception, the Free Software Foundation
22 gives permission to link the code of its release of Wget with the
23 OpenSSL project's "OpenSSL" library (or with modified versions of it
24 that use the same license as the "OpenSSL" library), and distribute
25 the linked executables. You must obey the GNU General Public License
26 in all respects for all of the code used other than "OpenSSL". If you
27 modify this file, you may extend this exception to your version of the
28 file, but you are not obligated to do so. If you do not wish to do
29 so, delete this exception statement from your version. */
40 #include <openssl/ssl.h>
41 #include <openssl/x509.h>
42 #include <openssl/err.h>
43 #include <openssl/rand.h>
51 /* Application-wide SSL context. This is common to all SSL
53 static SSL_CTX *ssl_ctx;
55 /* Initialize the SSL's PRNG using various methods. */
61 const char *random_file;
64 /* The PRNG has been seeded; no further action is necessary. */
67 /* Seed from a file specified by the user. This will be the file
68 specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it
71 random_file = opt.random_file;
74 /* Get the random file name using RAND_file_name. */
76 random_file = RAND_file_name (namebuf, sizeof (namebuf));
79 if (random_file && *random_file)
80 /* Seed at most 16k (apparently arbitrary value borrowed from
81 curl) from random file. */
82 RAND_load_file (random_file, 16384);
87 /* Get random data from EGD if opt.egd_file was used. */
88 if (opt.egd_file && *opt.egd_file)
89 RAND_egd (opt.egd_file);
95 /* Under Windows, we can try to seed the PRNG using screen content.
96 This may or may not work, depending on whether we'll calling Wget
104 #if 0 /* don't do this by default */
108 /* Still not random enough, presumably because neither /dev/random
109 nor EGD were available. Try to seed OpenSSL's PRNG with libc
110 PRNG. This is cryptographically weak and defeats the purpose
111 of using OpenSSL, which is why it is highly discouraged. */
113 logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n"));
115 while (RAND_status () == 0 && maxrand-- > 0)
117 unsigned char rnd = random_number (256);
118 RAND_seed (&rnd, sizeof (rnd));
124 /* Print errors in the OpenSSL error stack. */
130 while ((err = ERR_get_error ()) != 0)
131 logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL));
134 /* Convert keyfile type as used by options.h to a type as accepted by
135 SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file.
137 (options.h intentionally doesn't use values from openssl/ssl.h so
138 it doesn't depend specifically on OpenSSL for SSL functionality.) */
141 key_type_to_ssl_type (enum keyfile_type type)
146 return SSL_FILETYPE_PEM;
148 return SSL_FILETYPE_ASN1;
154 /* Create an SSL Context and set default paths etc. Called the first
155 time an HTTP download is attempted.
157 Returns true on success, false otherwise. */
165 /* The SSL has already been initialized. */
168 /* Init the PRNG. If that fails, bail out. */
170 if (RAND_status () != 1)
172 logprintf (LOG_NOTQUIET,
173 _("Could not seed PRNG; consider using --random-file.\n"));
178 SSL_load_error_strings ();
179 SSLeay_add_all_algorithms ();
180 SSLeay_add_ssl_algorithms ();
182 switch (opt.secure_protocol)
184 case secure_protocol_auto:
185 meth = SSLv23_client_method ();
187 case secure_protocol_sslv2:
188 meth = SSLv2_client_method ();
190 case secure_protocol_sslv3:
191 meth = SSLv3_client_method ();
193 case secure_protocol_tlsv1:
194 meth = TLSv1_client_method ();
200 ssl_ctx = SSL_CTX_new (meth);
204 SSL_CTX_set_default_verify_paths (ssl_ctx);
205 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
207 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
208 certificate is invalid. We verify the certificate separately in
209 ssl_check_certificate, which provides much better diagnostics
210 than examining the error stack after a failed SSL_connect. */
211 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
214 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
215 key_type_to_ssl_type (opt.cert_type))
219 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
220 key_type_to_ssl_type (opt.private_key_type))
224 /* Since fd_write unconditionally assumes partial writes (and
225 handles them correctly), allow them in OpenSSL. */
226 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
232 SSL_CTX_free (ssl_ctx);
238 openssl_read (int fd, char *buf, int bufsize, void *ctx)
243 ret = SSL_read (ssl, buf, bufsize);
245 && SSL_get_error (ssl, ret) == SSL_ERROR_SYSCALL
251 openssl_write (int fd, char *buf, int bufsize, void *ctx)
256 ret = SSL_write (ssl, buf, bufsize);
258 && SSL_get_error (ssl, ret) == SSL_ERROR_SYSCALL
264 openssl_poll (int fd, double timeout, int wait_for, void *ctx)
269 if (SSL_pending (ssl))
271 return select_fd (fd, timeout, wait_for);
275 openssl_peek (int fd, char *buf, int bufsize, void *ctx)
280 ret = SSL_peek (ssl, buf, bufsize);
282 && SSL_get_error (ssl, ret) == SSL_ERROR_SYSCALL
288 openssl_errstr (int fd, void *ctx)
290 /* Unfortunately we cannot use ERR_error_string's internal buffer
291 because we must be prepared to print more than one error. */
292 static char errbuf[512];
293 char *p = errbuf, *end = errbuf + sizeof errbuf;
296 if ((err = ERR_get_error ()) == 0)
297 /* Inform the caller that there have been no errors */
300 /* Iterate over OpenSSL's error stack and print errors to ERRBUF,
301 separated by "; ", while being careful not to overrun ERRBUF. */
304 ERR_error_string_n (err, p, end - p);
305 p = strchr (p, '\0');
306 err = ERR_get_error ();
309 if (p < end) *p++ = ';';
310 if (p < end) *p++ = ' ';
322 openssl_close (int fd, void *ctx)
334 DEBUGP (("Closed %d/SSL 0x%0lx\n", fd, (unsigned long) ssl));
337 /* openssl_transport is the singleton that describes the SSL transport
338 methods provided by this file. */
340 static struct transport_implementation openssl_transport = {
341 openssl_read, openssl_write, openssl_poll,
342 openssl_peek, openssl_errstr, openssl_close
345 /* Perform the SSL handshake on file descriptor FD, which is assumed
346 to be connected to an SSL server. The SSL handle provided by
347 OpenSSL is registered with the file descriptor FD using
348 fd_register_transport, so that subsequent calls to fd_read,
349 fd_write, etc., will use the corresponding SSL functions.
351 Returns true on success, false on failure. */
358 DEBUGP (("Initiating SSL handshake.\n"));
360 assert (ssl_ctx != NULL);
361 ssl = SSL_new (ssl_ctx);
364 if (!SSL_set_fd (ssl, fd))
366 SSL_set_connect_state (ssl);
367 if (SSL_connect (ssl) <= 0 || ssl->state != SSL_ST_OK)
370 /* Register FD with Wget's transport layer, i.e. arrange that our
371 functions are used for reading, writing, and polling. */
372 fd_register_transport (fd, &openssl_transport, ssl);
373 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
374 fd, PTR_FORMAT (ssl)));
378 DEBUGP (("SSL handshake failed.\n"));
385 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
387 /* Return true is STRING (case-insensitively) matches PATTERN, false
388 otherwise. The recognized wildcard character is "*", which matches
389 any character in STRING except ".". Any number of the "*" wildcard
390 may be present in the pattern.
392 This is used to match of hosts as indicated in rfc2818: "Names may
393 contain the wildcard character * which is considered to match any
394 single domain name component or component fragment. E.g., *.a.com
395 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
396 not bar.com [or foo.bar.com]."
398 If the pattern contain no wildcards, pattern_match(a, b) is
399 equivalent to !strcasecmp(a, b). */
402 pattern_match (const char *pattern, const char *string)
404 const char *p = pattern, *n = string;
406 for (; (c = TOLOWER (*p++)) != '\0'; n++)
409 for (c = TOLOWER (*p); c == '*'; c = TOLOWER (*++p))
411 for (; *n != '\0'; n++)
412 if (TOLOWER (*n) == c && pattern_match (p, n))
414 #ifdef ASTERISK_EXCLUDES_DOT
422 if (c != TOLOWER (*n))
428 /* Verify the validity of the certificate presented by the server.
429 Also check that the "common name" of the server, as presented by
430 its certificate, corresponds to HOST. (HOST typically comes from
431 the URL and is what the user thinks he's connecting to.)
433 This assumes that ssl_connect has successfully finished, i.e. that
434 the SSL handshake has been performed and that FD is connected to an
437 If opt.check_cert is true (the default), this returns 1 if the
438 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
439 function always returns 1, but should still be called because it
440 warns the user about any problems with the certificate. */
443 ssl_check_certificate (int fd, const char *host)
446 char common_name[256];
450 /* If the user has specified --no-check-cert, we still want to warn
451 him about problems with the server's certificate. */
452 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
454 SSL *ssl = (SSL *) fd_transport_context (fd);
455 assert (ssl != NULL);
457 cert = SSL_get_peer_certificate (ssl);
460 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
461 severity, escnonprint (host));
463 goto no_cert; /* must bail out since CERT is NULL */
468 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
469 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
470 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
471 escnonprint (subject), escnonprint (issuer)));
472 OPENSSL_free (subject);
473 OPENSSL_free (issuer);
476 vresult = SSL_get_verify_result (ssl);
477 if (vresult != X509_V_OK)
479 /* #### We might want to print saner (and translatable) error
480 messages for several frequently encountered errors. The
481 candidates would include
482 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY,
483 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN,
484 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT,
485 X509_V_ERR_CERT_NOT_YET_VALID, X509_V_ERR_CERT_HAS_EXPIRED,
486 and possibly others. The current approach would still be
487 used for the less frequent failure cases. */
488 logprintf (LOG_NOTQUIET,
489 _("%s: Certificate verification error for %s: %s\n"),
490 severity, escnonprint (host),
491 X509_verify_cert_error_string (vresult));
493 /* Fall through, so that the user is warned about *all* issues
494 with the cert (important with --no-check-certificate.) */
497 /* Check that HOST matches the common name in the certificate.
498 #### The following remains to be done:
500 - It should use dNSName/ipAddress subjectAltName extensions if
501 available; according to rfc2818: "If a subjectAltName extension
502 of type dNSName is present, that MUST be used as the identity."
504 - When matching against common names, it should loop over all
505 common names and choose the most specific one, i.e. the last
506 one, not the first one, which the current code picks.
508 - Ensure that ASN1 strings from the certificate are encoded as
509 UTF-8 which can be meaningfully compared to HOST. */
511 common_name[0] = '\0';
512 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
513 NID_commonName, common_name, sizeof (common_name));
514 if (!pattern_match (common_name, host))
516 logprintf (LOG_NOTQUIET, _("\
517 %s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
518 severity, escnonprint (common_name), escnonprint (host));
523 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
524 escnonprint (host)));
528 if (opt.check_cert && !success)
529 logprintf (LOG_NOTQUIET, _("\
530 To connect to %s insecurely, use `--no-check-certificate'.\n"),
533 /* Allow --no-check-cert to disable certificate checking. */
534 return opt.check_cert ? success : true;