588 lines
13 KiB
C
588 lines
13 KiB
C
/*
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* Copyright (C) 2012 Philip Van Hoof <philip@codeminded.be>
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* Copyright (C) 2009 Vic Lee.
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*
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* This 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 2 of the License, or
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* (at your option) any later version.
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*
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* This software 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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*
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* You should have received a copy of the GNU General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#include <rfb/rfbclient.h>
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#include <errno.h>
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#include <openssl/err.h>
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#include <openssl/ssl.h>
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#include <openssl/x509.h>
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#include <openssl/rand.h>
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#include <openssl/x509.h>
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#include <pthread.h>
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#include "tls.h"
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static rfbBool rfbTLSInitialized = FALSE;
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static pthread_mutex_t *mutex_buf = NULL;
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struct CRYPTO_dynlock_value {
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pthread_mutex_t mutex;
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};
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static void locking_function(int mode, int n, const char *file, int line)
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{
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if (mode & CRYPTO_LOCK)
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pthread_mutex_lock(&mutex_buf[n]);
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else
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pthread_mutex_unlock(&mutex_buf[n]);
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}
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static unsigned long id_function(void)
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{
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return ((unsigned long) pthread_self());
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}
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static struct CRYPTO_dynlock_value *dyn_create_function(const char *file, int line)
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{
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struct CRYPTO_dynlock_value *value;
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value = (struct CRYPTO_dynlock_value *)
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malloc(sizeof(struct CRYPTO_dynlock_value));
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if (!value)
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goto err;
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pthread_mutex_init(&value->mutex, NULL);
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return value;
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err:
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return (NULL);
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}
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static void dyn_lock_function (int mode, struct CRYPTO_dynlock_value *l, const char *file, int line)
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{
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if (mode & CRYPTO_LOCK)
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pthread_mutex_lock(&l->mutex);
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else
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pthread_mutex_unlock(&l->mutex);
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}
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static void
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dyn_destroy_function(struct CRYPTO_dynlock_value *l, const char *file, int line)
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{
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pthread_mutex_destroy(&l->mutex);
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free(l);
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}
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static int
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ssl_errno (SSL *ssl, int ret)
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{
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switch (SSL_get_error (ssl, ret)) {
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case SSL_ERROR_NONE:
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return 0;
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case SSL_ERROR_ZERO_RETURN:
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/* this one does not map well at all */
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//d(printf ("ssl_errno: SSL_ERROR_ZERO_RETURN\n"));
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return EINVAL;
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case SSL_ERROR_WANT_READ: /* non-fatal; retry */
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case SSL_ERROR_WANT_WRITE: /* non-fatal; retry */
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//d(printf ("ssl_errno: SSL_ERROR_WANT_[READ,WRITE]\n"));
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return EAGAIN;
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case SSL_ERROR_SYSCALL:
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//d(printf ("ssl_errno: SSL_ERROR_SYSCALL\n"));
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return EINTR;
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case SSL_ERROR_SSL:
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//d(printf ("ssl_errno: SSL_ERROR_SSL <-- very useful error...riiiiight\n"));
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return EINTR;
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default:
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//d(printf ("ssl_errno: default error\n"));
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return EINTR;
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}
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}
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static rfbBool
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InitializeTLS(void)
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{
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int i;
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if (rfbTLSInitialized) return TRUE;
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mutex_buf = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t));
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if (mutex_buf == NULL) {
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rfbClientLog("Failed to initialized OpenSSL: memory.\n");
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return (-1);
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}
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for (i = 0; i < CRYPTO_num_locks(); i++)
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pthread_mutex_init(&mutex_buf[i], NULL);
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CRYPTO_set_locking_callback(locking_function);
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CRYPTO_set_id_callback(id_function);
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CRYPTO_set_dynlock_create_callback(dyn_create_function);
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CRYPTO_set_dynlock_lock_callback(dyn_lock_function);
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CRYPTO_set_dynlock_destroy_callback(dyn_destroy_function);
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SSL_load_error_strings();
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SSLeay_add_ssl_algorithms();
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RAND_load_file("/dev/urandom", 1024);
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rfbClientLog("OpenSSL initialized.\n");
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rfbTLSInitialized = TRUE;
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return TRUE;
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}
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static int
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ssl_verify (int ok, X509_STORE_CTX *ctx)
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{
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unsigned char md5sum[16], fingerprint[40], *f;
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rfbClient *client;
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char *prompt, *cert_str;
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int err, i;
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unsigned int md5len;
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//char buf[257];
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X509 *cert;
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SSL *ssl;
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if (ok)
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return TRUE;
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ssl = X509_STORE_CTX_get_ex_data (ctx, SSL_get_ex_data_X509_STORE_CTX_idx ());
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client = SSL_CTX_get_app_data (ssl->ctx);
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cert = X509_STORE_CTX_get_current_cert (ctx);
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err = X509_STORE_CTX_get_error (ctx);
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/* calculate the MD5 hash of the raw certificate */
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md5len = sizeof (md5sum);
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X509_digest (cert, EVP_md5 (), md5sum, &md5len);
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for (i = 0, f = fingerprint; i < 16; i++, f += 3)
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sprintf ((char *) f, "%.2x%c", md5sum[i], i != 15 ? ':' : '\0');
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#define GET_STRING(name) X509_NAME_oneline (name, buf, 256)
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/* TODO: Don't just ignore certificate checks
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fingerprint = key to check in db
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GET_STRING (X509_get_issuer_name (cert));
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GET_STRING (X509_get_subject_name (cert));
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cert->valid (bool: GOOD or BAD) */
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ok = TRUE;
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return ok;
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}
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static int sock_read_ready(SSL *ssl, uint32_t ms)
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{
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int r = 0;
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fd_set fds;
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struct timeval tv;
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FD_ZERO(&fds);
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FD_SET(SSL_get_fd(ssl), &fds);
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tv.tv_sec = ms / 1000;
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tv.tv_usec = (ms % 1000) * ms;
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r = select (SSL_get_fd(ssl) + 1, &fds, NULL, NULL, &tv);
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return r;
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}
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static int wait_for_data(SSL *ssl, int ret, int timeout)
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{
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struct timeval tv;
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fd_set fds;
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int err;
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int retval = 1;
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err = SSL_get_error(ssl, ret);
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switch(err)
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{
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case SSL_ERROR_WANT_READ:
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case SSL_ERROR_WANT_WRITE:
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ret = sock_read_ready(ssl, timeout*1000);
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if (ret == -1) {
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retval = 2;
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}
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break;
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default:
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retval = 3;
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break;
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}
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ERR_clear_error();
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return retval;
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}
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static SSL *
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open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS)
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{
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SSL_CTX *ssl_ctx = NULL;
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SSL *ssl = NULL;
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int n, finished = 0;
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BIO *sbio;
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ssl_ctx = SSL_CTX_new (SSLv23_client_method ());
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SSL_CTX_set_default_verify_paths (ssl_ctx);
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SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, &ssl_verify);
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ssl = SSL_new (ssl_ctx);
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/* TODO: finetune this list, take into account anonTLS bool */
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SSL_set_cipher_list(ssl, "ALL");
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SSL_set_fd (ssl, sockfd);
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SSL_CTX_set_app_data (ssl_ctx, client);
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do
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{
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n = SSL_connect(ssl);
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if (n != 1)
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{
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if (wait_for_data(ssl, n, 1) != 1)
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{
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finished = 1;
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if (ssl->ctx)
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SSL_CTX_free (ssl->ctx);
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SSL_free(ssl);
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SSL_shutdown (ssl);
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return NULL;
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}
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}
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} while( n != 1 && finished != 1 );
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return ssl;
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}
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static rfbBool
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InitializeTLSSession(rfbClient* client, rfbBool anonTLS)
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{
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int ret;
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if (client->tlsSession) return TRUE;
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client->tlsSession = open_ssl_connection (client, client->sock, anonTLS);
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if (!client->tlsSession)
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return FALSE;
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rfbClientLog("TLS session initialized.\n");
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return TRUE;
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}
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static rfbBool
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SetTLSAnonCredential(rfbClient* client)
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{
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rfbClientLog("TLS anonymous credential created.\n");
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return TRUE;
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}
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static rfbBool
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HandshakeTLS(rfbClient* client)
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{
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int timeout = 15;
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int ret;
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return TRUE;
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while (timeout > 0 && (ret = SSL_do_handshake(client->tlsSession)) < 0)
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{
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if (ret != -1)
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{
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rfbClientLog("TLS handshake blocking.\n");
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sleep(1);
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timeout--;
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continue;
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}
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rfbClientLog("TLS handshake failed: -.\n");
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FreeTLS(client);
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return FALSE;
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}
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if (timeout <= 0)
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{
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rfbClientLog("TLS handshake timeout.\n");
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FreeTLS(client);
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return FALSE;
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}
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rfbClientLog("TLS handshake done.\n");
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return TRUE;
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}
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/* VeNCrypt sub auth. 1 byte auth count, followed by count * 4 byte integers */
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static rfbBool
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ReadVeNCryptSecurityType(rfbClient* client, uint32_t *result)
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{
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uint8_t count=0;
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uint8_t loop=0;
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uint8_t flag=0;
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uint32_t tAuth[256], t;
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char buf1[500],buf2[10];
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uint32_t authScheme;
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if (!ReadFromRFBServer(client, (char *)&count, 1)) return FALSE;
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if (count==0)
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{
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rfbClientLog("List of security types is ZERO. Giving up.\n");
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return FALSE;
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}
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if (count>sizeof(tAuth))
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{
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rfbClientLog("%d security types are too many; maximum is %d\n", count, sizeof(tAuth));
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return FALSE;
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}
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rfbClientLog("We have %d security types to read\n", count);
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authScheme=0;
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/* now, we have a list of available security types to read ( uint8_t[] ) */
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for (loop=0;loop<count;loop++)
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{
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if (!ReadFromRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
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t=rfbClientSwap32IfLE(tAuth[loop]);
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rfbClientLog("%d) Received security type %d\n", loop, t);
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if (flag) continue;
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if (t==rfbVeNCryptTLSNone ||
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t==rfbVeNCryptTLSVNC ||
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t==rfbVeNCryptTLSPlain ||
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t==rfbVeNCryptX509None ||
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t==rfbVeNCryptX509VNC ||
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t==rfbVeNCryptX509Plain)
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{
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flag++;
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authScheme=t;
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rfbClientLog("Selecting security type %d (%d/%d in the list)\n", authScheme, loop, count);
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/* send back 4 bytes (in original byte order!) indicating which security type to use */
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if (!WriteToRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
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}
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tAuth[loop]=t;
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}
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if (authScheme==0)
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{
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memset(buf1, 0, sizeof(buf1));
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for (loop=0;loop<count;loop++)
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{
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if (strlen(buf1)>=sizeof(buf1)-1) break;
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snprintf(buf2, sizeof(buf2), (loop>0 ? ", %d" : "%d"), (int)tAuth[loop]);
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strncat(buf1, buf2, sizeof(buf1)-strlen(buf1)-1);
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}
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rfbClientLog("Unknown VeNCrypt authentication scheme from VNC server: %s\n",
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buf1);
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return FALSE;
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}
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*result = authScheme;
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return TRUE;
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}
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rfbBool
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HandleAnonTLSAuth(rfbClient* client)
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{
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if (!InitializeTLS() || !InitializeTLSSession(client, TRUE)) return FALSE;
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if (!SetTLSAnonCredential(client)) return FALSE;
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if (!HandshakeTLS(client)) return FALSE;
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return TRUE;
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}
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rfbBool
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HandleVeNCryptAuth(rfbClient* client)
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{
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uint8_t major, minor, status;
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uint32_t authScheme;
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rfbBool anonTLS;
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// gnutls_certificate_credentials_t x509_cred = NULL;
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int ret;
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if (!InitializeTLS()) return FALSE;
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/* Read VeNCrypt version */
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if (!ReadFromRFBServer(client, (char *)&major, 1) ||
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!ReadFromRFBServer(client, (char *)&minor, 1))
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{
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return FALSE;
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}
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rfbClientLog("Got VeNCrypt version %d.%d from server.\n", (int)major, (int)minor);
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if (major != 0 && minor != 2)
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{
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rfbClientLog("Unsupported VeNCrypt version.\n");
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return FALSE;
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}
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if (!WriteToRFBServer(client, (char *)&major, 1) ||
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!WriteToRFBServer(client, (char *)&minor, 1) ||
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!ReadFromRFBServer(client, (char *)&status, 1))
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{
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return FALSE;
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}
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if (status != 0)
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{
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rfbClientLog("Server refused VeNCrypt version %d.%d.\n", (int)major, (int)minor);
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return FALSE;
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}
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if (!ReadVeNCryptSecurityType(client, &authScheme)) return FALSE;
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if (!ReadFromRFBServer(client, (char *)&status, 1) || status != 1)
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{
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rfbClientLog("Server refused VeNCrypt authentication %d (%d).\n", authScheme, (int)status);
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return FALSE;
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}
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client->subAuthScheme = authScheme;
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/* Some VeNCrypt security types are anonymous TLS, others are X509 */
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switch (authScheme)
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{
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case rfbVeNCryptTLSNone:
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case rfbVeNCryptTLSVNC:
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case rfbVeNCryptTLSPlain:
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anonTLS = TRUE;
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break;
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default:
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anonTLS = FALSE;
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break;
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}
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/* Get X509 Credentials if it's not anonymous */
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if (!anonTLS)
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{
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rfbCredential *cred;
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if (!client->GetCredential)
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{
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rfbClientLog("GetCredential callback is not set.\n");
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return FALSE;
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}
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cred = client->GetCredential(client, rfbCredentialTypeX509);
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if (!cred)
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{
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rfbClientLog("Reading credential failed\n");
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return FALSE;
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}
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/* TODO: don't just ignore this
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x509_cred = CreateX509CertCredential(cred);
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FreeX509Credential(cred);
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if (!x509_cred) return FALSE; */
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}
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/* Start up the TLS session */
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if (!InitializeTLSSession(client, anonTLS)) return FALSE;
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if (anonTLS)
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{
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if (!SetTLSAnonCredential(client)) return FALSE;
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}
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else
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{
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/* TODO: don't just ignore this
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if ((ret = gnutls_credentials_set(client->tlsSession, GNUTLS_CRD_CERTIFICATE, x509_cred)) < 0)
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{
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rfbClientLog("Cannot set x509 credential: %s.\n", gnutls_strerror(ret));
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FreeTLS(client); */
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return FALSE;
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// }
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}
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if (!HandshakeTLS(client)) return FALSE;
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/* TODO: validate certificate */
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/* We are done here. The caller should continue with client->subAuthScheme
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* to do actual sub authentication.
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*/
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return TRUE;
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}
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int
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ReadFromTLS(rfbClient* client, char *out, unsigned int n)
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{
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ssize_t ret;
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ret = SSL_read (client->tlsSession, out, n);
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if (ret >= 0)
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return ret;
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else {
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errno = ssl_errno (client->tlsSession, ret);
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if (errno != EAGAIN) {
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rfbClientLog("Error reading from TLS: -.\n");
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}
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}
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return -1;
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}
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int
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WriteToTLS(rfbClient* client, char *buf, unsigned int n)
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{
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unsigned int offset = 0;
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ssize_t ret;
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while (offset < n)
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{
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ret = SSL_write (client->tlsSession, buf + offset, (size_t)(n-offset));
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if (ret < 0)
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errno = ssl_errno (client->tlsSession, ret);
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if (ret == 0) continue;
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if (ret < 0)
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{
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if (errno == EAGAIN || errno == EWOULDBLOCK) continue;
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rfbClientLog("Error writing to TLS: -\n");
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return -1;
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}
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offset += (unsigned int)ret;
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}
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return offset;
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}
|
|
|
|
void FreeTLS(rfbClient* client)
|
|
{
|
|
int i;
|
|
|
|
if (mutex_buf != NULL) {
|
|
CRYPTO_set_dynlock_create_callback(NULL);
|
|
CRYPTO_set_dynlock_lock_callback(NULL);
|
|
CRYPTO_set_dynlock_destroy_callback(NULL);
|
|
|
|
CRYPTO_set_locking_callback(NULL);
|
|
CRYPTO_set_id_callback(NULL);
|
|
|
|
for (i = 0; i < CRYPTO_num_locks(); i++)
|
|
pthread_mutex_destroy(&mutex_buf[i]);
|
|
free(mutex_buf);
|
|
mutex_buf = NULL;
|
|
}
|
|
|
|
SSL_free(client->tlsSession);
|
|
}
|
|
|