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
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, 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
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. */
129 unsigned long curerr = 0;
130 while ((curerr = ERR_get_error ()) != 0)
131 logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (curerr, 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)
241 SSL *ssl = (SSL *) 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)
254 SSL *ssl = (SSL *) 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)
266 SSL *ssl = (SSL *) 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)
278 SSL *ssl = (SSL *) ctx;
280 ret = SSL_peek (ssl, buf, bufsize);
282 && SSL_get_error (ssl, ret) == SSL_ERROR_SYSCALL
288 openssl_close (int fd, void *ctx)
290 SSL *ssl = (SSL *) ctx;
300 DEBUGP (("Closed %d/SSL 0x%0lx\n", fd, (unsigned long) ssl));
303 /* Perform the SSL handshake on file descriptor FD, which is assumed
304 to be connected to an SSL server. The SSL handle provided by
305 OpenSSL is registered with the file descriptor FD using
306 fd_register_transport, so that subsequent calls to fd_read,
307 fd_write, etc., will use the corresponding SSL functions.
309 Returns true on success, false on failure. */
316 DEBUGP (("Initiating SSL handshake.\n"));
318 assert (ssl_ctx != NULL);
319 ssl = SSL_new (ssl_ctx);
322 if (!SSL_set_fd (ssl, fd))
324 SSL_set_connect_state (ssl);
325 if (SSL_connect (ssl) <= 0 || ssl->state != SSL_ST_OK)
328 /* Register FD with Wget's transport layer, i.e. arrange that our
329 functions are used for reading, writing, and polling. */
330 fd_register_transport (fd, openssl_read, openssl_write, openssl_poll,
331 openssl_peek, openssl_close, ssl);
332 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
333 fd, PTR_FORMAT (ssl)));
337 DEBUGP (("SSL handshake failed.\n"));
344 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
346 /* Return true is STRING (case-insensitively) matches PATTERN, false
347 otherwise. The recognized wildcard character is "*", which matches
348 any character in STRING except ".". Any number of the "*" wildcard
349 may be present in the pattern.
351 This is used to match of hosts as indicated in rfc2818: "Names may
352 contain the wildcard character * which is considered to match any
353 single domain name component or component fragment. E.g., *.a.com
354 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
355 not bar.com [or foo.bar.com]."
357 If the pattern contain no wildcards, pattern_match(a, b) is
358 equivalent to !strcasecmp(a, b). */
361 pattern_match (const char *pattern, const char *string)
363 const char *p = pattern, *n = string;
365 for (; (c = TOLOWER (*p++)) != '\0'; n++)
368 for (c = TOLOWER (*p); c == '*'; c = TOLOWER (*++p))
370 for (; *n != '\0'; n++)
371 if (TOLOWER (*n) == c && pattern_match (p, n))
373 #ifdef ASTERISK_EXCLUDES_DOT
381 if (c != TOLOWER (*n))
387 /* Verify the validity of the certificate presented by the server.
388 Also check that the "common name" of the server, as presented by
389 its certificate, corresponds to HOST. (HOST typically comes from
390 the URL and is what the user thinks he's connecting to.)
392 This assumes that ssl_connect has successfully finished, i.e. that
393 the SSL handshake has been performed and that FD is connected to an
396 If opt.check_cert is true (the default), this returns 1 if the
397 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
398 function always returns 1, but should still be called because it
399 warns the user about any problems with the certificate. */
402 ssl_check_certificate (int fd, const char *host)
405 char common_name[256];
409 /* If the user has specified --no-check-cert, we still want to warn
410 him about problems with the server's certificate. */
411 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
413 SSL *ssl = (SSL *) fd_transport_context (fd);
414 assert (ssl != NULL);
416 cert = SSL_get_peer_certificate (ssl);
419 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
420 severity, escnonprint (host));
422 goto no_cert; /* must bail out since CERT is NULL */
427 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
428 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
429 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
430 escnonprint (subject), escnonprint (issuer)));
431 OPENSSL_free (subject);
432 OPENSSL_free (issuer);
435 vresult = SSL_get_verify_result (ssl);
436 if (vresult != X509_V_OK)
438 /* #### We might want to print saner (and translatable) error
439 messages for several frequently encountered errors. The
440 candidates would include
441 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY,
442 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN,
443 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT,
444 X509_V_ERR_CERT_NOT_YET_VALID, X509_V_ERR_CERT_HAS_EXPIRED,
445 and possibly others. The current approach would still be
446 used for the less frequent failure cases. */
447 logprintf (LOG_NOTQUIET,
448 _("%s: Certificate verification error for %s: %s\n"),
449 severity, escnonprint (host),
450 X509_verify_cert_error_string (vresult));
452 /* Fall through, so that the user is warned about *all* issues
453 with the cert (important with --no-check-certificate.) */
456 /* Check that HOST matches the common name in the certificate.
457 #### The following remains to be done:
459 - It should use dNSName/ipAddress subjectAltName extensions if
460 available; according to rfc2818: "If a subjectAltName extension
461 of type dNSName is present, that MUST be used as the identity."
463 - When matching against common names, it should loop over all
464 common names and choose the most specific one, i.e. the last
465 one, not the first one, which the current code picks.
467 - Ensure that ASN1 strings from the certificate are encoded as
468 UTF-8 which can be meaningfully compared to HOST. */
470 common_name[0] = '\0';
471 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
472 NID_commonName, common_name, sizeof (common_name));
473 if (!pattern_match (common_name, host))
475 logprintf (LOG_NOTQUIET, _("\
476 %s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
477 severity, escnonprint (common_name), escnonprint (host));
482 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
483 escnonprint (host)));
487 if (opt.check_cert && !success)
488 logprintf (LOG_NOTQUIET, _("\
489 To connect to %s insecurely, use `--no-check-certificate'.\n"),
492 /* Allow --no-check-cert to disable certificate checking. */
493 return opt.check_cert ? success : true;