1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000-2006 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);
228 /* The OpenSSL library can handle renegotiations automatically, so
230 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
236 SSL_CTX_free (ssl_ctx);
241 struct openssl_transport_context {
242 SSL *conn; /* SSL connection handle */
243 char *last_error; /* last error printed with openssl_errstr */
247 openssl_read (int fd, char *buf, int bufsize, void *arg)
250 struct openssl_transport_context *ctx = arg;
251 SSL *conn = ctx->conn;
253 ret = SSL_read (conn, buf, bufsize);
255 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
261 openssl_write (int fd, char *buf, int bufsize, void *arg)
264 struct openssl_transport_context *ctx = arg;
265 SSL *conn = ctx->conn;
267 ret = SSL_write (conn, buf, bufsize);
269 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
275 openssl_poll (int fd, double timeout, int wait_for, void *arg)
277 struct openssl_transport_context *ctx = arg;
278 SSL *conn = ctx->conn;
281 if (SSL_pending (conn))
283 return select_fd (fd, timeout, wait_for);
287 openssl_peek (int fd, char *buf, int bufsize, void *arg)
290 struct openssl_transport_context *ctx = arg;
291 SSL *conn = ctx->conn;
293 ret = SSL_peek (conn, buf, bufsize);
295 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
301 openssl_errstr (int fd, void *arg)
303 struct openssl_transport_context *ctx = arg;
304 unsigned long errcode;
308 /* If there are no SSL-specific errors, just return NULL. */
309 if ((errcode = ERR_get_error ()) == 0)
312 /* Get rid of previous contents of ctx->last_error, if any. */
313 xfree_null (ctx->last_error);
315 /* Iterate over OpenSSL's error stack and accumulate errors in the
316 last_error buffer, separated by "; ". This is better than using
317 a static buffer, which *always* takes up space (and has to be
318 large, to fit more than one error message), whereas these
319 allocations are only performed when there is an actual error. */
323 const char *str = ERR_error_string (errcode, NULL);
324 int len = strlen (str);
326 /* Allocate space for the existing message, plus two more chars
327 for the "; " separator and one for the terminating \0. */
328 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
329 memcpy (errmsg + msglen, str, len);
332 /* Get next error and bail out if there are no more. */
333 errcode = ERR_get_error ();
337 errmsg[msglen++] = ';';
338 errmsg[msglen++] = ' ';
340 errmsg[msglen] = '\0';
342 /* Store the error in ctx->last_error where openssl_close will
343 eventually find it and free it. */
344 ctx->last_error = errmsg;
350 openssl_close (int fd, void *arg)
352 struct openssl_transport_context *ctx = arg;
353 SSL *conn = ctx->conn;
357 xfree_null (ctx->last_error);
366 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
369 /* openssl_transport is the singleton that describes the SSL transport
370 methods provided by this file. */
372 static struct transport_implementation openssl_transport = {
373 openssl_read, openssl_write, openssl_poll,
374 openssl_peek, openssl_errstr, openssl_close
377 /* Perform the SSL handshake on file descriptor FD, which is assumed
378 to be connected to an SSL server. The SSL handle provided by
379 OpenSSL is registered with the file descriptor FD using
380 fd_register_transport, so that subsequent calls to fd_read,
381 fd_write, etc., will use the corresponding SSL functions.
383 Returns true on success, false on failure. */
389 struct openssl_transport_context *ctx;
391 DEBUGP (("Initiating SSL handshake.\n"));
393 assert (ssl_ctx != NULL);
394 conn = SSL_new (ssl_ctx);
397 if (!SSL_set_fd (conn, fd))
399 SSL_set_connect_state (conn);
400 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
403 ctx = xnew0 (struct openssl_transport_context);
406 /* Register FD with Wget's transport layer, i.e. arrange that our
407 functions are used for reading, writing, and polling. */
408 fd_register_transport (fd, &openssl_transport, ctx);
409 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
410 fd, PTR_FORMAT (conn)));
414 DEBUGP (("SSL handshake failed.\n"));
421 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
423 /* Return true is STRING (case-insensitively) matches PATTERN, false
424 otherwise. The recognized wildcard character is "*", which matches
425 any character in STRING except ".". Any number of the "*" wildcard
426 may be present in the pattern.
428 This is used to match of hosts as indicated in rfc2818: "Names may
429 contain the wildcard character * which is considered to match any
430 single domain name component or component fragment. E.g., *.a.com
431 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
432 not bar.com [or foo.bar.com]."
434 If the pattern contain no wildcards, pattern_match(a, b) is
435 equivalent to !strcasecmp(a, b). */
438 pattern_match (const char *pattern, const char *string)
440 const char *p = pattern, *n = string;
442 for (; (c = TOLOWER (*p++)) != '\0'; n++)
445 for (c = TOLOWER (*p); c == '*'; c = TOLOWER (*++p))
447 for (; *n != '\0'; n++)
448 if (TOLOWER (*n) == c && pattern_match (p, n))
450 #ifdef ASTERISK_EXCLUDES_DOT
458 if (c != TOLOWER (*n))
464 /* Verify the validity of the certificate presented by the server.
465 Also check that the "common name" of the server, as presented by
466 its certificate, corresponds to HOST. (HOST typically comes from
467 the URL and is what the user thinks he's connecting to.)
469 This assumes that ssl_connect has successfully finished, i.e. that
470 the SSL handshake has been performed and that FD is connected to an
473 If opt.check_cert is true (the default), this returns 1 if the
474 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
475 function always returns 1, but should still be called because it
476 warns the user about any problems with the certificate. */
479 ssl_check_certificate (int fd, const char *host)
482 char common_name[256];
486 /* If the user has specified --no-check-cert, we still want to warn
487 him about problems with the server's certificate. */
488 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
490 struct openssl_transport_context *ctx = fd_transport_context (fd);
491 SSL *conn = ctx->conn;
492 assert (conn != NULL);
494 cert = SSL_get_peer_certificate (conn);
497 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
498 severity, escnonprint (host));
500 goto no_cert; /* must bail out since CERT is NULL */
505 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
506 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
507 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
508 escnonprint (subject), escnonprint (issuer)));
509 OPENSSL_free (subject);
510 OPENSSL_free (issuer);
513 vresult = SSL_get_verify_result (conn);
514 if (vresult != X509_V_OK)
516 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
517 logprintf (LOG_NOTQUIET,
518 _("%s: cannot verify %s's certificate, issued by `%s':\n"),
519 severity, escnonprint (host), escnonprint (issuer));
520 /* Try to print more user-friendly (and translated) messages for
521 the frequent verification errors. */
524 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
525 logprintf (LOG_NOTQUIET,
526 _(" Unable to locally verify the issuer's authority.\n"));
528 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
529 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
530 logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
532 case X509_V_ERR_CERT_NOT_YET_VALID:
533 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
535 case X509_V_ERR_CERT_HAS_EXPIRED:
536 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
539 /* For the less frequent error strings, simply provide the
540 OpenSSL error message. */
541 logprintf (LOG_NOTQUIET, " %s\n",
542 X509_verify_cert_error_string (vresult));
545 /* Fall through, so that the user is warned about *all* issues
546 with the cert (important with --no-check-certificate.) */
549 /* Check that HOST matches the common name in the certificate.
550 #### The following remains to be done:
552 - It should use dNSName/ipAddress subjectAltName extensions if
553 available; according to rfc2818: "If a subjectAltName extension
554 of type dNSName is present, that MUST be used as the identity."
556 - When matching against common names, it should loop over all
557 common names and choose the most specific one, i.e. the last
558 one, not the first one, which the current code picks.
560 - Ensure that ASN1 strings from the certificate are encoded as
561 UTF-8 which can be meaningfully compared to HOST. */
563 common_name[0] = '\0';
564 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
565 NID_commonName, common_name, sizeof (common_name));
566 if (!pattern_match (common_name, host))
568 logprintf (LOG_NOTQUIET, _("\
569 %s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
570 severity, escnonprint (common_name), escnonprint (host));
575 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
576 escnonprint (host)));
580 if (opt.check_cert && !success)
581 logprintf (LOG_NOTQUIET, _("\
582 To connect to %s insecurely, use `--no-check-certificate'.\n"),
585 /* Allow --no-check-cert to disable certificate checking. */
586 return opt.check_cert ? success : true;