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);
237 struct openssl_transport_context {
238 SSL *conn; /* SSL connection handle */
239 char *last_error; /* last error printed with openssl_errstr */
243 openssl_read (int fd, char *buf, int bufsize, void *arg)
246 struct openssl_transport_context *ctx = arg;
247 SSL *conn = ctx->conn;
249 ret = SSL_read (conn, buf, bufsize);
251 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
257 openssl_write (int fd, char *buf, int bufsize, void *arg)
260 struct openssl_transport_context *ctx = arg;
261 SSL *conn = ctx->conn;
263 ret = SSL_write (conn, buf, bufsize);
265 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
271 openssl_poll (int fd, double timeout, int wait_for, void *arg)
273 struct openssl_transport_context *ctx = arg;
274 SSL *conn = ctx->conn;
277 if (SSL_pending (conn))
279 return select_fd (fd, timeout, wait_for);
283 openssl_peek (int fd, char *buf, int bufsize, void *arg)
286 struct openssl_transport_context *ctx = arg;
287 SSL *conn = ctx->conn;
289 ret = SSL_peek (conn, buf, bufsize);
291 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
297 openssl_errstr (int fd, void *arg)
299 struct openssl_transport_context *ctx = arg;
300 unsigned long errcode;
304 /* If there are no SSL-specific errors, just return NULL. */
305 if ((errcode = ERR_get_error ()) == 0)
308 /* Get rid of previous contents of ctx->last_error, if any. */
309 xfree_null (ctx->last_error);
311 /* Iterate over OpenSSL's error stack and accumulate errors in the
312 last_error buffer, separated by "; ". This is better than using
313 a static buffer, which *always* takes up space (and has to be
314 large, to fit more than one error message), whereas these
315 allocations are only performed when there is an actual error. */
319 const char *str = ERR_error_string (errcode, NULL);
320 int len = strlen (str);
322 /* Allocate space for the existing message, plus two more chars
323 for the "; " separator and one for the terminating \0. */
324 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
325 memcpy (errmsg + msglen, str, len);
328 /* Get next error and bail out if there are no more. */
329 errcode = ERR_get_error ();
333 errmsg[msglen++] = ';';
334 errmsg[msglen++] = ' ';
336 errmsg[msglen] = '\0';
338 /* Store the error in ctx->last_error where openssl_close will
339 eventually find it and free it. */
340 ctx->last_error = errmsg;
346 openssl_close (int fd, void *arg)
348 struct openssl_transport_context *ctx = arg;
349 SSL *conn = ctx->conn;
353 xfree_null (ctx->last_error);
362 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
365 /* openssl_transport is the singleton that describes the SSL transport
366 methods provided by this file. */
368 static struct transport_implementation openssl_transport = {
369 openssl_read, openssl_write, openssl_poll,
370 openssl_peek, openssl_errstr, openssl_close
373 /* Perform the SSL handshake on file descriptor FD, which is assumed
374 to be connected to an SSL server. The SSL handle provided by
375 OpenSSL is registered with the file descriptor FD using
376 fd_register_transport, so that subsequent calls to fd_read,
377 fd_write, etc., will use the corresponding SSL functions.
379 Returns true on success, false on failure. */
385 struct openssl_transport_context *ctx;
387 DEBUGP (("Initiating SSL handshake.\n"));
389 assert (ssl_ctx != NULL);
390 conn = SSL_new (ssl_ctx);
393 if (!SSL_set_fd (conn, fd))
395 SSL_set_connect_state (conn);
396 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
399 ctx = xnew0 (struct openssl_transport_context);
402 /* Register FD with Wget's transport layer, i.e. arrange that our
403 functions are used for reading, writing, and polling. */
404 fd_register_transport (fd, &openssl_transport, ctx);
405 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
406 fd, PTR_FORMAT (conn)));
410 DEBUGP (("SSL handshake failed.\n"));
417 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
419 /* Return true is STRING (case-insensitively) matches PATTERN, false
420 otherwise. The recognized wildcard character is "*", which matches
421 any character in STRING except ".". Any number of the "*" wildcard
422 may be present in the pattern.
424 This is used to match of hosts as indicated in rfc2818: "Names may
425 contain the wildcard character * which is considered to match any
426 single domain name component or component fragment. E.g., *.a.com
427 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
428 not bar.com [or foo.bar.com]."
430 If the pattern contain no wildcards, pattern_match(a, b) is
431 equivalent to !strcasecmp(a, b). */
434 pattern_match (const char *pattern, const char *string)
436 const char *p = pattern, *n = string;
438 for (; (c = TOLOWER (*p++)) != '\0'; n++)
441 for (c = TOLOWER (*p); c == '*'; c = TOLOWER (*++p))
443 for (; *n != '\0'; n++)
444 if (TOLOWER (*n) == c && pattern_match (p, n))
446 #ifdef ASTERISK_EXCLUDES_DOT
454 if (c != TOLOWER (*n))
460 /* Verify the validity of the certificate presented by the server.
461 Also check that the "common name" of the server, as presented by
462 its certificate, corresponds to HOST. (HOST typically comes from
463 the URL and is what the user thinks he's connecting to.)
465 This assumes that ssl_connect has successfully finished, i.e. that
466 the SSL handshake has been performed and that FD is connected to an
469 If opt.check_cert is true (the default), this returns 1 if the
470 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
471 function always returns 1, but should still be called because it
472 warns the user about any problems with the certificate. */
475 ssl_check_certificate (int fd, const char *host)
478 char common_name[256];
482 /* If the user has specified --no-check-cert, we still want to warn
483 him about problems with the server's certificate. */
484 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
486 struct openssl_transport_context *ctx = fd_transport_context (fd);
487 SSL *conn = ctx->conn;
488 assert (conn != NULL);
490 cert = SSL_get_peer_certificate (conn);
493 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
494 severity, escnonprint (host));
496 goto no_cert; /* must bail out since CERT is NULL */
501 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
502 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
503 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
504 escnonprint (subject), escnonprint (issuer)));
505 OPENSSL_free (subject);
506 OPENSSL_free (issuer);
509 vresult = SSL_get_verify_result (conn);
510 if (vresult != X509_V_OK)
512 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
513 logprintf (LOG_NOTQUIET,
514 _("%s: cannot verify %s's certificate, issued by `%s':\n"),
515 severity, escnonprint (host), escnonprint (issuer));
516 /* Try to print more user-friendly (and translated) messages for
517 the frequent verification errors. */
520 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
521 logprintf (LOG_NOTQUIET,
522 _(" Unable to locally verify the issuer's authority.\n"));
524 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
525 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
526 logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
528 case X509_V_ERR_CERT_NOT_YET_VALID:
529 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
531 case X509_V_ERR_CERT_HAS_EXPIRED:
532 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
535 /* For the less frequent error strings, simply provide the
536 OpenSSL error message. */
537 logprintf (LOG_NOTQUIET, " %s\n",
538 X509_verify_cert_error_string (vresult));
541 /* Fall through, so that the user is warned about *all* issues
542 with the cert (important with --no-check-certificate.) */
545 /* Check that HOST matches the common name in the certificate.
546 #### The following remains to be done:
548 - It should use dNSName/ipAddress subjectAltName extensions if
549 available; according to rfc2818: "If a subjectAltName extension
550 of type dNSName is present, that MUST be used as the identity."
552 - When matching against common names, it should loop over all
553 common names and choose the most specific one, i.e. the last
554 one, not the first one, which the current code picks.
556 - Ensure that ASN1 strings from the certificate are encoded as
557 UTF-8 which can be meaningfully compared to HOST. */
559 common_name[0] = '\0';
560 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
561 NID_commonName, common_name, sizeof (common_name));
562 if (!pattern_match (common_name, host))
564 logprintf (LOG_NOTQUIET, _("\
565 %s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
566 severity, escnonprint (common_name), escnonprint (host));
571 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
572 escnonprint (host)));
576 if (opt.check_cert && !success)
577 logprintf (LOG_NOTQUIET, _("\
578 To connect to %s insecurely, use `--no-check-certificate'.\n"),
581 /* Allow --no-check-cert to disable certificate checking. */
582 return opt.check_cert ? success : true;