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/* SSL support via OpenSSL library.
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Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
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2009 Free Software Foundation, Inc.
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Originally contributed by Christian Fraenkel.
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This file is part of GNU Wget.
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GNU Wget is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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GNU Wget is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Wget. If not, see <http://www.gnu.org/licenses/>.
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Additional permission under GNU GPL version 3 section 7
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If you modify this program, or any covered work, by linking or
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combining it with the OpenSSL project's OpenSSL library (or a
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modified version of that library), containing parts covered by the
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terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
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grants you additional permission to convey the resulting work.
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Corresponding Source for a non-source form of such a combination
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shall include the source code for the parts of OpenSSL used as well
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as that of the covered work. */
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#include <openssl/ssl.h>
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#include <openssl/x509.h>
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#include <openssl/err.h>
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#include <openssl/rand.h>
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/* Application-wide SSL context. This is common to all SSL
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static SSL_CTX *ssl_ctx;
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/* Initialize the SSL's PRNG using various methods. */
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const char *random_file;
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/* The PRNG has been seeded; no further action is necessary. */
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/* Seed from a file specified by the user. This will be the file
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specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it
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random_file = opt.random_file;
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/* Get the random file name using RAND_file_name. */
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random_file = RAND_file_name (namebuf, sizeof (namebuf));
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if (random_file && *random_file)
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/* Seed at most 16k (apparently arbitrary value borrowed from
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curl) from random file. */
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RAND_load_file (random_file, 16384);
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/* Get random data from EGD if opt.egd_file was used. */
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if (opt.egd_file && *opt.egd_file)
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RAND_egd (opt.egd_file);
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/* Under Windows, we can try to seed the PRNG using screen content.
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This may or may not work, depending on whether we'll calling Wget
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#if 0 /* don't do this by default */
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/* Still not random enough, presumably because neither /dev/random
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nor EGD were available. Try to seed OpenSSL's PRNG with libc
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PRNG. This is cryptographically weak and defeats the purpose
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of using OpenSSL, which is why it is highly discouraged. */
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logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n"));
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while (RAND_status () == 0 && maxrand-- > 0)
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unsigned char rnd = random_number (256);
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RAND_seed (&rnd, sizeof (rnd));
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/* Print errors in the OpenSSL error stack. */
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while ((err = ERR_get_error ()) != 0)
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logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL));
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/* Convert keyfile type as used by options.h to a type as accepted by
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SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file.
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(options.h intentionally doesn't use values from openssl/ssl.h so
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it doesn't depend specifically on OpenSSL for SSL functionality.) */
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key_type_to_ssl_type (enum keyfile_type type)
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return SSL_FILETYPE_PEM;
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return SSL_FILETYPE_ASN1;
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/* Create an SSL Context and set default paths etc. Called the first
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time an HTTP download is attempted.
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Returns true on success, false otherwise. */
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/* The SSL has already been initialized. */
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/* Init the PRNG. If that fails, bail out. */
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if (RAND_status () != 1)
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logprintf (LOG_NOTQUIET,
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_("Could not seed PRNG; consider using --random-file.\n"));
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SSL_load_error_strings ();
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SSLeay_add_all_algorithms ();
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SSLeay_add_ssl_algorithms ();
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switch (opt.secure_protocol)
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case secure_protocol_auto:
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meth = SSLv23_client_method ();
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case secure_protocol_sslv2:
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meth = SSLv2_client_method ();
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case secure_protocol_sslv3:
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meth = SSLv3_client_method ();
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case secure_protocol_tlsv1:
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meth = TLSv1_client_method ();
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ssl_ctx = SSL_CTX_new (meth);
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SSL_CTX_set_default_verify_paths (ssl_ctx);
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SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
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/* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
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certificate is invalid. We verify the certificate separately in
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ssl_check_certificate, which provides much better diagnostics
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than examining the error stack after a failed SSL_connect. */
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SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
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/* Use the private key from the cert file unless otherwise specified. */
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if (opt.cert_file && !opt.private_key)
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opt.private_key = opt.cert_file;
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opt.private_key_type = opt.cert_type;
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if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
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key_type_to_ssl_type (opt.cert_type))
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if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
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key_type_to_ssl_type (opt.private_key_type))
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/* Since fd_write unconditionally assumes partial writes (and
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handles them correctly), allow them in OpenSSL. */
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SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
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/* The OpenSSL library can handle renegotiations automatically, so
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SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
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SSL_CTX_free (ssl_ctx);
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struct openssl_transport_context {
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SSL *conn; /* SSL connection handle */
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char *last_error; /* last error printed with openssl_errstr */
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openssl_read (int fd, char *buf, int bufsize, void *arg)
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struct openssl_transport_context *ctx = arg;
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SSL *conn = ctx->conn;
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ret = SSL_read (conn, buf, bufsize);
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&& SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
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openssl_write (int fd, char *buf, int bufsize, void *arg)
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struct openssl_transport_context *ctx = arg;
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SSL *conn = ctx->conn;
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ret = SSL_write (conn, buf, bufsize);
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&& SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
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openssl_poll (int fd, double timeout, int wait_for, void *arg)
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struct openssl_transport_context *ctx = arg;
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SSL *conn = ctx->conn;
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if (SSL_pending (conn))
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return select_fd (fd, timeout, wait_for);
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openssl_peek (int fd, char *buf, int bufsize, void *arg)
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struct openssl_transport_context *ctx = arg;
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SSL *conn = ctx->conn;
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ret = SSL_peek (conn, buf, bufsize);
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&& SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
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openssl_errstr (int fd, void *arg)
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struct openssl_transport_context *ctx = arg;
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unsigned long errcode;
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/* If there are no SSL-specific errors, just return NULL. */
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if ((errcode = ERR_get_error ()) == 0)
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/* Get rid of previous contents of ctx->last_error, if any. */
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xfree_null (ctx->last_error);
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/* Iterate over OpenSSL's error stack and accumulate errors in the
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last_error buffer, separated by "; ". This is better than using
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a static buffer, which *always* takes up space (and has to be
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large, to fit more than one error message), whereas these
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allocations are only performed when there is an actual error. */
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const char *str = ERR_error_string (errcode, NULL);
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int len = strlen (str);
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/* Allocate space for the existing message, plus two more chars
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for the "; " separator and one for the terminating \0. */
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errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
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memcpy (errmsg + msglen, str, len);
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/* Get next error and bail out if there are no more. */
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errcode = ERR_get_error ();
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errmsg[msglen++] = ';';
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errmsg[msglen++] = ' ';
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errmsg[msglen] = '\0';
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/* Store the error in ctx->last_error where openssl_close will
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eventually find it and free it. */
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ctx->last_error = errmsg;
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openssl_close (int fd, void *arg)
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struct openssl_transport_context *ctx = arg;
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SSL *conn = ctx->conn;
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xfree_null (ctx->last_error);
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#if defined(WINDOWS) || defined(USE_WATT32)
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DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
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/* openssl_transport is the singleton that describes the SSL transport
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methods provided by this file. */
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static struct transport_implementation openssl_transport = {
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openssl_read, openssl_write, openssl_poll,
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openssl_peek, openssl_errstr, openssl_close
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/* Perform the SSL handshake on file descriptor FD, which is assumed
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to be connected to an SSL server. The SSL handle provided by
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OpenSSL is registered with the file descriptor FD using
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fd_register_transport, so that subsequent calls to fd_read,
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fd_write, etc., will use the corresponding SSL functions.
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Returns true on success, false on failure. */
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ssl_connect_wget (int fd)
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struct openssl_transport_context *ctx;
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DEBUGP (("Initiating SSL handshake.\n"));
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assert (ssl_ctx != NULL);
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conn = SSL_new (ssl_ctx);
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if (!SSL_set_fd (conn, fd))
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SSL_set_connect_state (conn);
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if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
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ctx = xnew0 (struct openssl_transport_context);
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/* Register FD with Wget's transport layer, i.e. arrange that our
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functions are used for reading, writing, and polling. */
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fd_register_transport (fd, &openssl_transport, ctx);
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DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
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fd, PTR_FORMAT (conn)));
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DEBUGP (("SSL handshake failed.\n"));
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#define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
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/* Return true is STRING (case-insensitively) matches PATTERN, false
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otherwise. The recognized wildcard character is "*", which matches
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any character in STRING except ".". Any number of the "*" wildcard
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may be present in the pattern.
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This is used to match of hosts as indicated in rfc2818: "Names may
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contain the wildcard character * which is considered to match any
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single domain name component or component fragment. E.g., *.a.com
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matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
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not bar.com [or foo.bar.com]."
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If the pattern contain no wildcards, pattern_match(a, b) is
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equivalent to !strcasecmp(a, b). */
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pattern_match (const char *pattern, const char *string)
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const char *p = pattern, *n = string;
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for (; (c = c_tolower (*p++)) != '\0'; n++)
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for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
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for (; *n != '\0'; n++)
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if (c_tolower (*n) == c && pattern_match (p, n))
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#ifdef ASTERISK_EXCLUDES_DOT
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if (c != c_tolower (*n))
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/* Verify the validity of the certificate presented by the server.
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Also check that the "common name" of the server, as presented by
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its certificate, corresponds to HOST. (HOST typically comes from
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the URL and is what the user thinks he's connecting to.)
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This assumes that ssl_connect_wget has successfully finished, i.e. that
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the SSL handshake has been performed and that FD is connected to an
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If opt.check_cert is true (the default), this returns 1 if the
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certificate is valid, 0 otherwise. If opt.check_cert is 0, the
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function always returns 1, but should still be called because it
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warns the user about any problems with the certificate. */
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ssl_check_certificate (int fd, const char *host)
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char common_name[256];
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/* If the user has specified --no-check-cert, we still want to warn
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him about problems with the server's certificate. */
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const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
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struct openssl_transport_context *ctx = fd_transport_context (fd);
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SSL *conn = ctx->conn;
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assert (conn != NULL);
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cert = SSL_get_peer_certificate (conn);
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logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
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severity, quotearg_style (escape_quoting_style, host));
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goto no_cert; /* must bail out since CERT is NULL */
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char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
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char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
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DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
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quotearg_n_style (0, escape_quoting_style, subject),
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quotearg_n_style (1, escape_quoting_style, issuer)));
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OPENSSL_free (subject);
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OPENSSL_free (issuer);
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vresult = SSL_get_verify_result (conn);
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if (vresult != X509_V_OK)
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char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
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logprintf (LOG_NOTQUIET,
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_("%s: cannot verify %s's certificate, issued by %s:\n"),
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severity, quotearg_n_style (0, escape_quoting_style, host),
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quote_n (1, issuer));
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/* Try to print more user-friendly (and translated) messages for
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the frequent verification errors. */
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case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
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logprintf (LOG_NOTQUIET,
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_(" Unable to locally verify the issuer's authority.\n"));
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case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
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case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
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logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
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case X509_V_ERR_CERT_NOT_YET_VALID:
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logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
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case X509_V_ERR_CERT_HAS_EXPIRED:
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logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
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/* For the less frequent error strings, simply provide the
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OpenSSL error message. */
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logprintf (LOG_NOTQUIET, " %s\n",
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X509_verify_cert_error_string (vresult));
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/* Fall through, so that the user is warned about *all* issues
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with the cert (important with --no-check-certificate.) */
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/* Check that HOST matches the common name in the certificate.
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#### The following remains to be done:
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- It should use dNSName/ipAddress subjectAltName extensions if
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available; according to rfc2818: "If a subjectAltName extension
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of type dNSName is present, that MUST be used as the identity."
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- When matching against common names, it should loop over all
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common names and choose the most specific one, i.e. the last
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one, not the first one, which the current code picks.
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- Ensure that ASN1 strings from the certificate are encoded as
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UTF-8 which can be meaningfully compared to HOST. */
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X509_NAME *xname = X509_get_subject_name(cert);
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common_name[0] = '\0';
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X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
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sizeof (common_name));
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if (!pattern_match (common_name, host))
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logprintf (LOG_NOTQUIET, _("\
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%s: certificate common name %s doesn't match requested host name %s.\n"),
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severity, quote_n (0, common_name), quote_n (1, host));
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/* We now determine the length of the ASN1 string. If it differs from
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* common_name's length, then there is a \0 before the string terminates.
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* This can be an instance of a null-prefix attack.
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* https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
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X509_NAME_ENTRY *xentry;
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j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
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xentry = X509_NAME_get_entry(xname,i);
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sdata = X509_NAME_ENTRY_get_data(xentry);
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if (strlen (common_name) != ASN1_STRING_length (sdata))
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logprintf (LOG_NOTQUIET, _("\
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%s: certificate common name is invalid (contains a NUL character).\n\
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This may be an indication that the host is not who it claims to be\n\
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(that is, it is not the real %s).\n"),
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severity, quote (host));
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DEBUGP (("X509 certificate successfully verified and matches host %s\n",
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quotearg_style (escape_quoting_style, host)));
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if (opt.check_cert && !success)
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logprintf (LOG_NOTQUIET, _("\
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To connect to %s insecurely, use `--no-check-certificate'.\n"),
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quotearg_style (escape_quoting_style, host));
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/* Allow --no-check-cert to disable certificate checking. */
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return opt.check_cert ? success : true;
added
removed
.pc/disable-SSLv2/src/openssl.c
