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[tor-commits] [tor/release-0.3.5] Merge branch 'maint-0.3.4' into maint-0.3.5



commit 896d0ebb994cc0b1df2c9497fcf3afe55654d01f
Merge: 76ed869ff 1fce9d129
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date:   Sun Nov 11 18:05:45 2018 -0500

    Merge branch 'maint-0.3.4' into maint-0.3.5

 src/lib/tls/tortls_openssl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --cc src/lib/tls/tortls_openssl.c
index 235620714,000000000..63f6259a6
mode 100644,000000..100644
--- a/src/lib/tls/tortls_openssl.c
+++ b/src/lib/tls/tortls_openssl.c
@@@ -1,1751 -1,0 +1,1751 @@@
 +/* Copyright (c) 2003, Roger Dingledine.
 + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 + * Copyright (c) 2007-2018, The Tor Project, Inc. */
 +/* See LICENSE for licensing information */
 +
 +/**
 + * \file tortls.c
 + * \brief Wrapper functions to present a consistent interface to
 + * TLS, SSL, and X.509 functions from OpenSSL.
 + **/
 +
 +/* (Unlike other tor functions, these
 + * are prefixed with tor_ in order to avoid conflicting with OpenSSL
 + * functions and variables.)
 + */
 +
 +#include "orconfig.h"
 +
 +#define TORTLS_PRIVATE
 +#define TORTLS_OPENSSL_PRIVATE
 +#define TOR_X509_PRIVATE
 +
 +#ifdef _WIN32
 +  /* We need to include these here, or else the dtls1.h header will include
 +   * <winsock.h> and mess things up, in at least some openssl versions. */
 +  #include <winsock2.h>
 +  #include <ws2tcpip.h>
 +#endif
 +
 +#include "lib/crypt_ops/crypto_cipher.h"
 +#include "lib/crypt_ops/crypto_rand.h"
 +#include "lib/crypt_ops/crypto_dh.h"
 +#include "lib/crypt_ops/crypto_util.h"
 +#include "lib/crypt_ops/compat_openssl.h"
 +#include "lib/tls/x509.h"
 +#include "lib/tls/x509_internal.h"
 +
 +/* Some versions of OpenSSL declare SSL_get_selected_srtp_profile twice in
 + * srtp.h. Suppress the GCC warning so we can build with -Wredundant-decl. */
 +DISABLE_GCC_WARNING(redundant-decls)
 +
 +#include <openssl/opensslv.h>
 +
 +#ifdef OPENSSL_NO_EC
 +#error "We require OpenSSL with ECC support"
 +#endif
 +
 +#include <openssl/ssl.h>
 +#include <openssl/ssl3.h>
 +#include <openssl/err.h>
 +#include <openssl/tls1.h>
 +#include <openssl/asn1.h>
 +#include <openssl/bio.h>
 +#include <openssl/bn.h>
 +#include <openssl/rsa.h>
 +
 +ENABLE_GCC_WARNING(redundant-decls)
 +
 +#include "lib/tls/tortls.h"
 +#include "lib/tls/tortls_st.h"
 +#include "lib/tls/tortls_internal.h"
 +#include "lib/log/log.h"
 +#include "lib/log/util_bug.h"
 +#include "lib/container/smartlist.h"
 +#include "lib/string/compat_string.h"
 +#include "lib/string/printf.h"
 +#include "lib/net/socket.h"
 +#include "lib/intmath/cmp.h"
 +#include "lib/ctime/di_ops.h"
 +#include "lib/encoding/time_fmt.h"
 +
 +#include <stdlib.h>
 +#include <string.h>
 +
 +#include "lib/arch/bytes.h"
 +
 +/* Copied from or.h */
 +#define LEGAL_NICKNAME_CHARACTERS \
 +  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 +
 +#define ADDR(tls) (((tls) && (tls)->address) ? tls->address : "peer")
 +
 +#if OPENSSL_VERSION_NUMBER <  OPENSSL_V(1,0,0,'f')
 +/* This is a version of OpenSSL before 1.0.0f. It does not have
 + * the CVE-2011-4576 fix, and as such it can't use RELEASE_BUFFERS and
 + * SSL3 safely at the same time.
 + */
 +#define DISABLE_SSL3_HANDSHAKE
 +#endif /* OPENSSL_VERSION_NUMBER <  OPENSSL_V(1,0,0,'f') */
 +
 +/* We redefine these so that we can run correctly even if the vendor gives us
 + * a version of OpenSSL that does not match its header files.  (Apple: I am
 + * looking at you.)
 + */
 +#ifndef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
 +#define SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION 0x00040000L
 +#endif
 +#ifndef SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
 +#define SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION 0x0010
 +#endif
 +
 +/** Return values for tor_tls_classify_client_ciphers.
 + *
 + * @{
 + */
 +/** An error occurred when examining the client ciphers */
 +#define CIPHERS_ERR -1
 +/** The client cipher list indicates that a v1 handshake was in use. */
 +#define CIPHERS_V1 1
 +/** The client cipher list indicates that the client is using the v2 or the
 + * v3 handshake, but that it is (probably!) lying about what ciphers it
 + * supports */
 +#define CIPHERS_V2 2
 +/** The client cipher list indicates that the client is using the v2 or the
 + * v3 handshake, and that it is telling the truth about what ciphers it
 + * supports */
 +#define CIPHERS_UNRESTRICTED 3
 +/** @} */
 +
 +/** The ex_data index in which we store a pointer to an SSL object's
 + * corresponding tor_tls_t object. */
 +STATIC int tor_tls_object_ex_data_index = -1;
 +
 +/** Helper: Allocate tor_tls_object_ex_data_index. */
 +void
 +tor_tls_allocate_tor_tls_object_ex_data_index(void)
 +{
 +  if (tor_tls_object_ex_data_index == -1) {
 +    tor_tls_object_ex_data_index =
 +      SSL_get_ex_new_index(0, NULL, NULL, NULL, NULL);
 +    tor_assert(tor_tls_object_ex_data_index != -1);
 +  }
 +}
 +
 +/** Helper: given a SSL* pointer, return the tor_tls_t object using that
 + * pointer. */
 +tor_tls_t *
 +tor_tls_get_by_ssl(const SSL *ssl)
 +{
 +  tor_tls_t *result = SSL_get_ex_data(ssl, tor_tls_object_ex_data_index);
 +  if (result)
 +    tor_assert(result->magic == TOR_TLS_MAGIC);
 +  return result;
 +}
 +
 +/** True iff tor_tls_init() has been called. */
 +static int tls_library_is_initialized = 0;
 +
 +/* Module-internal error codes. */
 +#define TOR_TLS_SYSCALL_    (MIN_TOR_TLS_ERROR_VAL_ - 2)
 +#define TOR_TLS_ZERORETURN_ (MIN_TOR_TLS_ERROR_VAL_ - 1)
 +
 +/** Write a description of the current state of <b>tls</b> into the
 + * <b>sz</b>-byte buffer at <b>buf</b>. */
 +void
 +tor_tls_get_state_description(tor_tls_t *tls, char *buf, size_t sz)
 +{
 +  const char *ssl_state;
 +  const char *tortls_state;
 +
 +  if (PREDICT_UNLIKELY(!tls || !tls->ssl)) {
 +    strlcpy(buf, "(No SSL object)", sz);
 +    return;
 +  }
 +
 +  ssl_state = SSL_state_string_long(tls->ssl);
 +  switch (tls->state) {
 +#define CASE(st) case TOR_TLS_ST_##st: tortls_state = " in "#st ; break
 +    CASE(HANDSHAKE);
 +    CASE(OPEN);
 +    CASE(GOTCLOSE);
 +    CASE(SENTCLOSE);
 +    CASE(CLOSED);
 +    CASE(RENEGOTIATE);
 +#undef CASE
 +  case TOR_TLS_ST_BUFFEREVENT:
 +    tortls_state = "";
 +    break;
 +  default:
 +    tortls_state = " in unknown TLS state";
 +    break;
 +  }
 +
 +  tor_snprintf(buf, sz, "%s%s", ssl_state, tortls_state);
 +}
 +
 +/** Log a single error <b>err</b> as returned by ERR_get_error(), which was
 + * received while performing an operation <b>doing</b> on <b>tls</b>.  Log
 + * the message at <b>severity</b>, in log domain <b>domain</b>. */
 +void
 +tor_tls_log_one_error(tor_tls_t *tls, unsigned long err,
 +                  int severity, int domain, const char *doing)
 +{
 +  const char *state = NULL, *addr;
 +  const char *msg, *lib, *func;
 +
 +  state = (tls && tls->ssl)?SSL_state_string_long(tls->ssl):"---";
 +
 +  addr = tls ? tls->address : NULL;
 +
 +  /* Some errors are known-benign, meaning they are the fault of the other
 +   * side of the connection. The caller doesn't know this, so override the
 +   * priority for those cases. */
 +  switch (ERR_GET_REASON(err)) {
 +    case SSL_R_HTTP_REQUEST:
 +    case SSL_R_HTTPS_PROXY_REQUEST:
 +    case SSL_R_RECORD_LENGTH_MISMATCH:
 +#ifndef OPENSSL_1_1_API
 +    case SSL_R_RECORD_TOO_LARGE:
 +#endif
 +    case SSL_R_UNKNOWN_PROTOCOL:
 +    case SSL_R_UNSUPPORTED_PROTOCOL:
 +      severity = LOG_INFO;
 +      break;
 +    default:
 +      break;
 +  }
 +
 +  msg = (const char*)ERR_reason_error_string(err);
 +  lib = (const char*)ERR_lib_error_string(err);
 +  func = (const char*)ERR_func_error_string(err);
 +  if (!msg) msg = "(null)";
 +  if (!lib) lib = "(null)";
 +  if (!func) func = "(null)";
 +  if (doing) {
 +    tor_log(severity, domain, "TLS error while %s%s%s: %s (in %s:%s:%s)",
 +        doing, addr?" with ":"", addr?addr:"",
 +        msg, lib, func, state);
 +  } else {
 +    tor_log(severity, domain, "TLS error%s%s: %s (in %s:%s:%s)",
 +        addr?" with ":"", addr?addr:"",
 +        msg, lib, func, state);
 +  }
 +}
 +
 +/** Log all pending tls errors at level <b>severity</b> in log domain
 + * <b>domain</b>.  Use <b>doing</b> to describe our current activities.
 + */
 +void
 +tls_log_errors(tor_tls_t *tls, int severity, int domain, const char *doing)
 +{
 +  unsigned long err;
 +
 +  while ((err = ERR_get_error()) != 0) {
 +    tor_tls_log_one_error(tls, err, severity, domain, doing);
 +  }
 +}
 +
 +#define CATCH_SYSCALL 1
 +#define CATCH_ZERO    2
 +
 +/** Given a TLS object and the result of an SSL_* call, use
 + * SSL_get_error to determine whether an error has occurred, and if so
 + * which one.  Return one of TOR_TLS_{DONE|WANTREAD|WANTWRITE|ERROR}.
 + * If extra&CATCH_SYSCALL is true, return TOR_TLS_SYSCALL_ instead of
 + * reporting syscall errors.  If extra&CATCH_ZERO is true, return
 + * TOR_TLS_ZERORETURN_ instead of reporting zero-return errors.
 + *
 + * If an error has occurred, log it at level <b>severity</b> and describe the
 + * current action as <b>doing</b>.
 + */
 +int
 +tor_tls_get_error(tor_tls_t *tls, int r, int extra,
 +                  const char *doing, int severity, int domain)
 +{
 +  int err = SSL_get_error(tls->ssl, r);
 +  int tor_error = TOR_TLS_ERROR_MISC;
 +  switch (err) {
 +    case SSL_ERROR_NONE:
 +      return TOR_TLS_DONE;
 +    case SSL_ERROR_WANT_READ:
 +      return TOR_TLS_WANTREAD;
 +    case SSL_ERROR_WANT_WRITE:
 +      return TOR_TLS_WANTWRITE;
 +    case SSL_ERROR_SYSCALL:
 +      if (extra&CATCH_SYSCALL)
 +        return TOR_TLS_SYSCALL_;
 +      if (r == 0) {
 +        tor_log(severity, LD_NET, "TLS error: unexpected close while %s (%s)",
 +            doing, SSL_state_string_long(tls->ssl));
 +        tor_error = TOR_TLS_ERROR_IO;
 +      } else {
 +        int e = tor_socket_errno(tls->socket);
 +        tor_log(severity, LD_NET,
 +            "TLS error: <syscall error while %s> (errno=%d: %s; state=%s)",
 +            doing, e, tor_socket_strerror(e),
 +            SSL_state_string_long(tls->ssl));
 +        tor_error = tor_errno_to_tls_error(e);
 +      }
 +      tls_log_errors(tls, severity, domain, doing);
 +      return tor_error;
 +    case SSL_ERROR_ZERO_RETURN:
 +      if (extra&CATCH_ZERO)
 +        return TOR_TLS_ZERORETURN_;
 +      tor_log(severity, LD_NET, "TLS connection closed while %s in state %s",
 +          doing, SSL_state_string_long(tls->ssl));
 +      tls_log_errors(tls, severity, domain, doing);
 +      return TOR_TLS_CLOSE;
 +    default:
 +      tls_log_errors(tls, severity, domain, doing);
 +      return TOR_TLS_ERROR_MISC;
 +  }
 +}
 +
 +/** Initialize OpenSSL, unless it has already been initialized.
 + */
 +void
 +tor_tls_init(void)
 +{
 +  check_no_tls_errors();
 +
 +  if (!tls_library_is_initialized) {
 +#ifdef OPENSSL_1_1_API
 +    OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS, NULL);
 +#else
 +    SSL_library_init();
 +    SSL_load_error_strings();
 +#endif
 +
 +#if (SIZEOF_VOID_P >= 8 &&                              \
 +     OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,0,1))
 +    long version = OpenSSL_version_num();
 +
 +    /* LCOV_EXCL_START : we can't test these lines on the same machine */
 +    if (version >= OPENSSL_V_SERIES(1,0,1)) {
 +      /* Warn if we could *almost* be running with much faster ECDH.
 +         If we're built for a 64-bit target, using OpenSSL 1.0.1, but we
 +         don't have one of the built-in __uint128-based speedups, we are
 +         just one build operation away from an accelerated handshake.
 +
 +         (We could be looking at OPENSSL_NO_EC_NISTP_64_GCC_128 instead of
 +          doing this test, but that gives compile-time options, not runtime
 +          behavior.)
 +      */
 +      EC_KEY *key = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
 +      const EC_GROUP *g = key ? EC_KEY_get0_group(key) : NULL;
 +      const EC_METHOD *m = g ? EC_GROUP_method_of(g) : NULL;
 +      const int warn = (m == EC_GFp_simple_method() ||
 +                        m == EC_GFp_mont_method() ||
 +                        m == EC_GFp_nist_method());
 +      EC_KEY_free(key);
 +
 +      if (warn)
 +        log_notice(LD_GENERAL, "We were built to run on a 64-bit CPU, with "
 +                   "OpenSSL 1.0.1 or later, but with a version of OpenSSL "
 +                   "that apparently lacks accelerated support for the NIST "
 +                   "P-224 and P-256 groups. Building openssl with such "
 +                   "support (using the enable-ec_nistp_64_gcc_128 option "
 +                   "when configuring it) would make ECDH much faster.");
 +    }
 +    /* LCOV_EXCL_STOP */
 +#endif /* (SIZEOF_VOID_P >= 8 &&                              ... */
 +
 +    tor_tls_allocate_tor_tls_object_ex_data_index();
 +
 +    tls_library_is_initialized = 1;
 +  }
 +}
 +
 +/** We need to give OpenSSL a callback to verify certificates. This is
 + * it: We always accept peer certs and complete the handshake.  We
 + * don't validate them until later.
 + */
 +int
 +always_accept_verify_cb(int preverify_ok,
 +                        X509_STORE_CTX *x509_ctx)
 +{
 +  (void) preverify_ok;
 +  (void) x509_ctx;
 +  return 1;
 +}
 +
 +/** List of ciphers that servers should select from when the client might be
 + * claiming extra unsupported ciphers in order to avoid fingerprinting.  */
 +static const char SERVER_CIPHER_LIST[] =
 +#ifdef  TLS1_3_TXT_AES_128_GCM_SHA256
 +  /* This one can never actually get selected, since if the client lists it,
 +   * we will assume that the client is honest, and not use this list.
 +   * Nonetheless we list it if it's available, so that the server doesn't
 +   * conclude that it has no valid ciphers if it's running with TLS1.3.
 +   */
 +  TLS1_3_TXT_AES_128_GCM_SHA256 ":"
 +#endif
 +  TLS1_TXT_DHE_RSA_WITH_AES_256_SHA ":"
 +  TLS1_TXT_DHE_RSA_WITH_AES_128_SHA;
 +
 +/** List of ciphers that servers should select from when we actually have
 + * our choice of what cipher to use. */
 +static const char UNRESTRICTED_SERVER_CIPHER_LIST[] =
 +  /* Here are the TLS 1.3 ciphers we like, in the order we prefer. */
 +#ifdef TLS1_3_TXT_AES_256_GCM_SHA384
 +  TLS1_3_TXT_AES_256_GCM_SHA384 ":"
 +#endif
 +#ifdef TLS1_3_TXT_CHACHA20_POLY1305_SHA256
 +  TLS1_3_TXT_CHACHA20_POLY1305_SHA256 ":"
 +#endif
 +#ifdef TLS1_3_TXT_AES_128_GCM_SHA256
 +  TLS1_3_TXT_AES_128_GCM_SHA256 ":"
 +#endif
 +#ifdef TLS1_3_TXT_AES_128_CCM_SHA256
 +  TLS1_3_TXT_AES_128_CCM_SHA256 ":"
 +#endif
 +
 +  /* This list is autogenerated with the gen_server_ciphers.py script;
 +   * don't hand-edit it. */
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_GCM_SHA384
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_256_GCM_SHA384 ":"
 +#endif
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256 ":"
 +#endif
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_SHA384
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_256_SHA384 ":"
 +#endif
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_SHA256
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_128_SHA256 ":"
 +#endif
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA ":"
 +#endif
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_CBC_SHA
 +       TLS1_TXT_ECDHE_RSA_WITH_AES_128_CBC_SHA ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_256_GCM_SHA384
 +       TLS1_TXT_DHE_RSA_WITH_AES_256_GCM_SHA384 ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_128_GCM_SHA256
 +       TLS1_TXT_DHE_RSA_WITH_AES_128_GCM_SHA256 ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_256_CCM
 +       TLS1_TXT_DHE_RSA_WITH_AES_256_CCM ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_128_CCM
 +       TLS1_TXT_DHE_RSA_WITH_AES_128_CCM ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_256_SHA256
 +       TLS1_TXT_DHE_RSA_WITH_AES_256_SHA256 ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_AES_128_SHA256
 +       TLS1_TXT_DHE_RSA_WITH_AES_128_SHA256 ":"
 +#endif
 +       /* Required */
 +       TLS1_TXT_DHE_RSA_WITH_AES_256_SHA ":"
 +       /* Required */
 +       TLS1_TXT_DHE_RSA_WITH_AES_128_SHA ":"
 +#ifdef TLS1_TXT_ECDHE_RSA_WITH_CHACHA20_POLY1305
 +       TLS1_TXT_ECDHE_RSA_WITH_CHACHA20_POLY1305 ":"
 +#endif
 +#ifdef TLS1_TXT_DHE_RSA_WITH_CHACHA20_POLY1305
 +       TLS1_TXT_DHE_RSA_WITH_CHACHA20_POLY1305
 +#endif
 +  ;
 +
 +/* Note: to set up your own private testing network with link crypto
 + * disabled, set your Tors' cipher list to
 + * (SSL3_TXT_RSA_NULL_SHA).  If you do this, you won't be able to communicate
 + * with any of the "real" Tors, though. */
 +
 +#define CIPHER(id, name) name ":"
 +#define XCIPHER(id, name)
 +/** List of ciphers that clients should advertise, omitting items that
 + * our OpenSSL doesn't know about. */
 +static const char CLIENT_CIPHER_LIST[] =
 +#include "ciphers.inc"
 +  /* Tell it not to use SSLv2 ciphers, so that it can select an SSLv3 version
 +   * of any cipher we say. */
 +  "!SSLv2"
 +  ;
 +#undef CIPHER
 +#undef XCIPHER
 +
 +/** Return true iff the other side of <b>tls</b> has authenticated to us, and
 + * the key certified in <b>cert</b> is the same as the key they used to do it.
 + */
 +MOCK_IMPL(int,
 +tor_tls_cert_matches_key,(const tor_tls_t *tls, const tor_x509_cert_t *cert))
 +{
 +  tor_x509_cert_t *peer = tor_tls_get_peer_cert((tor_tls_t *)tls);
 +  if (!peer)
 +    return 0;
 +
 +  X509 *peercert = peer->cert;
 +  EVP_PKEY *link_key = NULL, *cert_key = NULL;
 +  int result;
 +
 +  link_key = X509_get_pubkey(peercert);
 +  cert_key = X509_get_pubkey(cert->cert);
 +
 +  result = link_key && cert_key && EVP_PKEY_cmp(cert_key, link_key) == 1;
 +
 +  tor_x509_cert_free(peer);
 +  if (link_key)
 +    EVP_PKEY_free(link_key);
 +  if (cert_key)
 +    EVP_PKEY_free(cert_key);
 +
 +  return result;
 +}
 +
 +void
 +tor_tls_context_impl_free_(struct ssl_ctx_st *ctx)
 +{
 +  if (!ctx)
 +    return;
 +  SSL_CTX_free(ctx);
 +}
 +
 +/** The group we should use for ecdhe when none was selected. */
 +#define  NID_tor_default_ecdhe_group NID_X9_62_prime256v1
 +
 +/** Create a new TLS context for use with Tor TLS handshakes.
 + * <b>identity</b> should be set to the identity key used to sign the
 + * certificate.
 + */
 +tor_tls_context_t *
 +tor_tls_context_new(crypto_pk_t *identity, unsigned int key_lifetime,
 +                    unsigned flags, int is_client)
 +{
 +  EVP_PKEY *pkey = NULL;
 +  tor_tls_context_t *result = NULL;
 +
 +  tor_tls_init();
 +
 +  result = tor_malloc_zero(sizeof(tor_tls_context_t));
 +  result->refcnt = 1;
 +
 +  if (! is_client) {
 +    if (tor_tls_context_init_certificates(result, identity, key_lifetime,
 +                                          flags) < 0) {
 +      goto error;
 +    }
 +  }
 +
 +#if 0
 +  /* Tell OpenSSL to only use TLS1.  This may have subtly different results
 +   * from SSLv23_method() with SSLv2 and SSLv3 disabled, so we need to do some
 +   * investigation before we consider adjusting it. It should be compatible
 +   * with existing Tors. */
 +  if (!(result->ctx = SSL_CTX_new(TLSv1_method())))
 +    goto error;
 +#endif /* 0 */
 +
 +  /* Tell OpenSSL to use TLS 1.0 or later but not SSL2 or SSL3. */
 +#ifdef HAVE_TLS_METHOD
 +  if (!(result->ctx = SSL_CTX_new(TLS_method())))
 +    goto error;
 +#else
 +  if (!(result->ctx = SSL_CTX_new(SSLv23_method())))
 +    goto error;
 +#endif /* defined(HAVE_TLS_METHOD) */
 +
 +#ifdef HAVE_SSL_CTX_SET_SECURITY_LEVEL
 +  /* Level 1 re-enables RSA1024 and DH1024 for compatibility with old tors */
 +  SSL_CTX_set_security_level(result->ctx, 1);
 +#endif
 +
 +  SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv2);
 +  SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv3);
 +
 +  /* Prefer the server's ordering of ciphers: the client's ordering has
 +  * historically been chosen for fingerprinting resistance. */
 +  SSL_CTX_set_options(result->ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
 +
 +  /* Disable TLS tickets if they're supported.  We never want to use them;
 +   * using them can make our perfect forward secrecy a little worse, *and*
 +   * create an opportunity to fingerprint us (since it's unusual to use them
 +   * with TLS sessions turned off).
 +   *
 +   * In 0.2.4, clients advertise support for them though, to avoid a TLS
 +   * distinguishability vector.  This can give us worse PFS, though, if we
 +   * get a server that doesn't set SSL_OP_NO_TICKET.  With luck, there will
 +   * be few such servers by the time 0.2.4 is more stable.
 +   */
 +#ifdef SSL_OP_NO_TICKET
 +  if (! is_client) {
 +    SSL_CTX_set_options(result->ctx, SSL_OP_NO_TICKET);
 +  }
 +#endif
 +
 +  SSL_CTX_set_options(result->ctx, SSL_OP_SINGLE_DH_USE);
 +  SSL_CTX_set_options(result->ctx, SSL_OP_SINGLE_ECDH_USE);
 +
 +#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
 +  SSL_CTX_set_options(result->ctx,
 +                      SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
 +#endif
 +  /* Yes, we know what we are doing here.  No, we do not treat a renegotiation
 +   * as authenticating any earlier-received data.
 +   */
 +  {
 +    SSL_CTX_set_options(result->ctx,
 +                        SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION);
 +  }
 +
 +  /* Don't actually allow compression; it uses RAM and time, it makes TLS
 +   * vulnerable to CRIME-style attacks, and most of the data we transmit over
 +   * TLS is encrypted (and therefore uncompressible) anyway. */
 +#ifdef SSL_OP_NO_COMPRESSION
 +  SSL_CTX_set_options(result->ctx, SSL_OP_NO_COMPRESSION);
 +#endif
 +#if OPENSSL_VERSION_NUMBER < OPENSSL_V_SERIES(1,1,0)
 +#ifndef OPENSSL_NO_COMP
 +  if (result->ctx->comp_methods)
 +    result->ctx->comp_methods = NULL;
 +#endif
 +#endif /* OPENSSL_VERSION_NUMBER < OPENSSL_V_SERIES(1,1,0) */
 +
 +#ifdef SSL_MODE_RELEASE_BUFFERS
 +  SSL_CTX_set_mode(result->ctx, SSL_MODE_RELEASE_BUFFERS);
 +#endif
 +  if (! is_client) {
 +    if (result->my_link_cert &&
 +        !SSL_CTX_use_certificate(result->ctx,
 +                                 result->my_link_cert->cert)) {
 +      goto error;
 +    }
 +    if (result->my_id_cert) {
 +      X509_STORE *s = SSL_CTX_get_cert_store(result->ctx);
 +      tor_assert(s);
 +      X509_STORE_add_cert(s, result->my_id_cert->cert);
 +    }
 +  }
 +  SSL_CTX_set_session_cache_mode(result->ctx, SSL_SESS_CACHE_OFF);
 +  if (!is_client) {
 +    tor_assert(result->link_key);
 +    if (!(pkey = crypto_pk_get_openssl_evp_pkey_(result->link_key,1)))
 +      goto error;
 +    if (!SSL_CTX_use_PrivateKey(result->ctx, pkey))
 +      goto error;
 +    EVP_PKEY_free(pkey);
 +    pkey = NULL;
 +    if (!SSL_CTX_check_private_key(result->ctx))
 +      goto error;
 +  }
 +
 +  {
 +    DH *dh = crypto_dh_new_openssl_tls();
 +    tor_assert(dh);
 +    SSL_CTX_set_tmp_dh(result->ctx, dh);
 +    DH_free(dh);
 +  }
 +/* We check for this function in two ways, since it might be either a symbol
 + * or a macro. */
 +#if defined(SSL_CTX_set1_groups_list) || defined(HAVE_SSL_CTX_SET1_GROUPS_LIST)
 +  {
 +    const char *list;
 +    if (flags & TOR_TLS_CTX_USE_ECDHE_P224)
 +      list = "P-224:P-256";
 +    else if (flags & TOR_TLS_CTX_USE_ECDHE_P256)
 +      list = "P-256:P-224";
 +    else
 +      list = "P-256:P-224";
-     int r = SSL_CTX_set1_groups_list(result->ctx, list);
++    int r = (int) SSL_CTX_set1_groups_list(result->ctx, list);
 +    if (r < 0)
 +      goto error;
 +  }
 +#else
 +  if (! is_client) {
 +    int nid;
 +    EC_KEY *ec_key;
 +    if (flags & TOR_TLS_CTX_USE_ECDHE_P224)
 +      nid = NID_secp224r1;
 +    else if (flags & TOR_TLS_CTX_USE_ECDHE_P256)
 +      nid = NID_X9_62_prime256v1;
 +    else
 +      nid = NID_tor_default_ecdhe_group;
 +    /* Use P-256 for ECDHE. */
 +    ec_key = EC_KEY_new_by_curve_name(nid);
 +    if (ec_key != NULL) /*XXXX Handle errors? */
 +      SSL_CTX_set_tmp_ecdh(result->ctx, ec_key);
 +    EC_KEY_free(ec_key);
 +  }
 +#endif
 +  SSL_CTX_set_verify(result->ctx, SSL_VERIFY_PEER,
 +                     always_accept_verify_cb);
 +  /* let us realloc bufs that we're writing from */
 +  SSL_CTX_set_mode(result->ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
 +
 +  return result;
 +
 + error:
 +  tls_log_errors(NULL, LOG_WARN, LD_NET, "creating TLS context");
 +  if (pkey)
 +    EVP_PKEY_free(pkey);
 +  tor_tls_context_decref(result);
 +  return NULL;
 +}
 +
 +/** Invoked when a TLS state changes: log the change at severity 'debug' */
 +void
 +tor_tls_debug_state_callback(const SSL *ssl, int type, int val)
 +{
 +  /* LCOV_EXCL_START since this depends on whether debug is captured or not */
 +  log_debug(LD_HANDSHAKE, "SSL %p is now in state %s [type=%d,val=%d].",
 +            ssl, SSL_state_string_long(ssl), type, val);
 +  /* LCOV_EXCL_STOP */
 +}
 +
 +/* Return the name of the negotiated ciphersuite in use on <b>tls</b> */
 +const char *
 +tor_tls_get_ciphersuite_name(tor_tls_t *tls)
 +{
 +  return SSL_get_cipher(tls->ssl);
 +}
 +
 +/* Here's the old V2 cipher list we sent from 0.2.1.1-alpha up to
 + * 0.2.3.17-beta. If a client is using this list, we can't believe the ciphers
 + * that it claims to support.  We'll prune this list to remove the ciphers
 + * *we* don't recognize. */
 +STATIC uint16_t v2_cipher_list[] = {
 +  0xc00a, /* TLS1_TXT_ECDHE_ECDSA_WITH_AES_256_CBC_SHA */
 +  0xc014, /* TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA */
 +  0x0039, /* TLS1_TXT_DHE_RSA_WITH_AES_256_SHA */
 +  0x0038, /* TLS1_TXT_DHE_DSS_WITH_AES_256_SHA */
 +  0xc00f, /* TLS1_TXT_ECDH_RSA_WITH_AES_256_CBC_SHA */
 +  0xc005, /* TLS1_TXT_ECDH_ECDSA_WITH_AES_256_CBC_SHA */
 +  0x0035, /* TLS1_TXT_RSA_WITH_AES_256_SHA */
 +  0xc007, /* TLS1_TXT_ECDHE_ECDSA_WITH_RC4_128_SHA */
 +  0xc009, /* TLS1_TXT_ECDHE_ECDSA_WITH_AES_128_CBC_SHA */
 +  0xc011, /* TLS1_TXT_ECDHE_RSA_WITH_RC4_128_SHA */
 +  0xc013, /* TLS1_TXT_ECDHE_RSA_WITH_AES_128_CBC_SHA */
 +  0x0033, /* TLS1_TXT_DHE_RSA_WITH_AES_128_SHA */
 +  0x0032, /* TLS1_TXT_DHE_DSS_WITH_AES_128_SHA */
 +  0xc00c, /* TLS1_TXT_ECDH_RSA_WITH_RC4_128_SHA */
 +  0xc00e, /* TLS1_TXT_ECDH_RSA_WITH_AES_128_CBC_SHA */
 +  0xc002, /* TLS1_TXT_ECDH_ECDSA_WITH_RC4_128_SHA */
 +  0xc004, /* TLS1_TXT_ECDH_ECDSA_WITH_AES_128_CBC_SHA */
 +  0x0004, /* SSL3_TXT_RSA_RC4_128_MD5 */
 +  0x0005, /* SSL3_TXT_RSA_RC4_128_SHA */
 +  0x002f, /* TLS1_TXT_RSA_WITH_AES_128_SHA */
 +  0xc008, /* TLS1_TXT_ECDHE_ECDSA_WITH_DES_192_CBC3_SHA */
 +  0xc012, /* TLS1_TXT_ECDHE_RSA_WITH_DES_192_CBC3_SHA */
 +  0x0016, /* SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA */
 +  0x0013, /* SSL3_TXT_EDH_DSS_DES_192_CBC3_SHA */
 +  0xc00d, /* TLS1_TXT_ECDH_RSA_WITH_DES_192_CBC3_SHA */
 +  0xc003, /* TLS1_TXT_ECDH_ECDSA_WITH_DES_192_CBC3_SHA */
 +  0xfeff, /* SSL3_TXT_RSA_FIPS_WITH_3DES_EDE_CBC_SHA */
 +  0x000a, /* SSL3_TXT_RSA_DES_192_CBC3_SHA */
 +  0
 +};
 +/** Have we removed the unrecognized ciphers from v2_cipher_list yet? */
 +static int v2_cipher_list_pruned = 0;
 +
 +/** Return 0 if <b>m</b> does not support the cipher with ID <b>cipher</b>;
 + * return 1 if it does support it, or if we have no way to tell. */
 +int
 +find_cipher_by_id(const SSL *ssl, const SSL_METHOD *m, uint16_t cipher)
 +{
 +  const SSL_CIPHER *c;
 +#ifdef HAVE_SSL_CIPHER_FIND
 +  (void) m;
 +  {
 +    unsigned char cipherid[3];
 +    tor_assert(ssl);
 +    set_uint16(cipherid, tor_htons(cipher));
 +    cipherid[2] = 0; /* If ssl23_get_cipher_by_char finds no cipher starting
 +                      * with a two-byte 'cipherid', it may look for a v2
 +                      * cipher with the appropriate 3 bytes. */
 +    c = SSL_CIPHER_find((SSL*)ssl, cipherid);
 +    if (c)
 +      tor_assert((SSL_CIPHER_get_id(c) & 0xffff) == cipher);
 +    return c != NULL;
 +  }
 +#else /* !(defined(HAVE_SSL_CIPHER_FIND)) */
 +
 +# if defined(HAVE_STRUCT_SSL_METHOD_ST_GET_CIPHER_BY_CHAR)
 +  if (m && m->get_cipher_by_char) {
 +    unsigned char cipherid[3];
 +    set_uint16(cipherid, tor_htons(cipher));
 +    cipherid[2] = 0; /* If ssl23_get_cipher_by_char finds no cipher starting
 +                      * with a two-byte 'cipherid', it may look for a v2
 +                      * cipher with the appropriate 3 bytes. */
 +    c = m->get_cipher_by_char(cipherid);
 +    if (c)
 +      tor_assert((c->id & 0xffff) == cipher);
 +    return c != NULL;
 +  }
 +#endif /* defined(HAVE_STRUCT_SSL_METHOD_ST_GET_CIPHER_BY_CHAR) */
 +# ifndef OPENSSL_1_1_API
 +  if (m && m->get_cipher && m->num_ciphers) {
 +    /* It would seem that some of the "let's-clean-up-openssl" forks have
 +     * removed the get_cipher_by_char function.  Okay, so now you get a
 +     * quadratic search.
 +     */
 +    int i;
 +    for (i = 0; i < m->num_ciphers(); ++i) {
 +      c = m->get_cipher(i);
 +      if (c && (c->id & 0xffff) == cipher) {
 +        return 1;
 +      }
 +    }
 +    return 0;
 +  }
 +#endif /* !defined(OPENSSL_1_1_API) */
 +  (void) ssl;
 +  (void) m;
 +  (void) cipher;
 +  return 1; /* No way to search */
 +#endif /* defined(HAVE_SSL_CIPHER_FIND) */
 +}
 +
 +/** Remove from v2_cipher_list every cipher that we don't support, so that
 + * comparing v2_cipher_list to a client's cipher list will give a sensible
 + * result. */
 +static void
 +prune_v2_cipher_list(const SSL *ssl)
 +{
 +  uint16_t *inp, *outp;
 +#ifdef HAVE_TLS_METHOD
 +  const SSL_METHOD *m = TLS_method();
 +#else
 +  const SSL_METHOD *m = SSLv23_method();
 +#endif
 +
 +  inp = outp = v2_cipher_list;
 +  while (*inp) {
 +    if (find_cipher_by_id(ssl, m, *inp)) {
 +      *outp++ = *inp++;
 +    } else {
 +      inp++;
 +    }
 +  }
 +  *outp = 0;
 +
 +  v2_cipher_list_pruned = 1;
 +}
 +
 +/** Examine the client cipher list in <b>ssl</b>, and determine what kind of
 + * client it is.  Return one of CIPHERS_ERR, CIPHERS_V1, CIPHERS_V2,
 + * CIPHERS_UNRESTRICTED.
 + **/
 +int
 +tor_tls_classify_client_ciphers(const SSL *ssl,
 +                                STACK_OF(SSL_CIPHER) *peer_ciphers)
 +{
 +  int i, res;
 +  tor_tls_t *tor_tls;
 +  if (PREDICT_UNLIKELY(!v2_cipher_list_pruned))
 +    prune_v2_cipher_list(ssl);
 +
 +  tor_tls = tor_tls_get_by_ssl(ssl);
 +  if (tor_tls && tor_tls->client_cipher_list_type)
 +    return tor_tls->client_cipher_list_type;
 +
 +  /* If we reached this point, we just got a client hello.  See if there is
 +   * a cipher list. */
 +  if (!peer_ciphers) {
 +    log_info(LD_NET, "No ciphers on session");
 +    res = CIPHERS_ERR;
 +    goto done;
 +  }
 +  /* Now we need to see if there are any ciphers whose presence means we're
 +   * dealing with an updated Tor. */
 +  for (i = 0; i < sk_SSL_CIPHER_num(peer_ciphers); ++i) {
 +    const SSL_CIPHER *cipher = sk_SSL_CIPHER_value(peer_ciphers, i);
 +    const char *ciphername = SSL_CIPHER_get_name(cipher);
 +    if (strcmp(ciphername, TLS1_TXT_DHE_RSA_WITH_AES_128_SHA) &&
 +        strcmp(ciphername, TLS1_TXT_DHE_RSA_WITH_AES_256_SHA) &&
 +        strcmp(ciphername, SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA) &&
 +        strcmp(ciphername, "(NONE)")) {
 +      log_debug(LD_NET, "Got a non-version-1 cipher called '%s'", ciphername);
 +      // return 1;
 +      goto v2_or_higher;
 +    }
 +  }
 +  res = CIPHERS_V1;
 +  goto done;
 + v2_or_higher:
 +  {
 +    const uint16_t *v2_cipher = v2_cipher_list;
 +    for (i = 0; i < sk_SSL_CIPHER_num(peer_ciphers); ++i) {
 +      const SSL_CIPHER *cipher = sk_SSL_CIPHER_value(peer_ciphers, i);
 +      uint16_t id = SSL_CIPHER_get_id(cipher) & 0xffff;
 +      if (id == 0x00ff) /* extended renegotiation indicator. */
 +        continue;
 +      if (!id || id != *v2_cipher) {
 +        res = CIPHERS_UNRESTRICTED;
 +        goto dump_ciphers;
 +      }
 +      ++v2_cipher;
 +    }
 +    if (*v2_cipher != 0) {
 +      res = CIPHERS_UNRESTRICTED;
 +      goto dump_ciphers;
 +    }
 +    res = CIPHERS_V2;
 +  }
 +
 + dump_ciphers:
 +  {
 +    smartlist_t *elts = smartlist_new();
 +    char *s;
 +    for (i = 0; i < sk_SSL_CIPHER_num(peer_ciphers); ++i) {
 +      const SSL_CIPHER *cipher = sk_SSL_CIPHER_value(peer_ciphers, i);
 +      const char *ciphername = SSL_CIPHER_get_name(cipher);
 +      smartlist_add(elts, (char*)ciphername);
 +    }
 +    s = smartlist_join_strings(elts, ":", 0, NULL);
 +    log_debug(LD_NET, "Got a %s V2/V3 cipher list from %s.  It is: '%s'",
 +              (res == CIPHERS_V2) ? "fictitious" : "real", ADDR(tor_tls), s);
 +    tor_free(s);
 +    smartlist_free(elts);
 +  }
 + done:
 +  if (tor_tls)
 +    return tor_tls->client_cipher_list_type = res;
 +
 +  return res;
 +}
 +
 +/** Return true iff the cipher list suggested by the client for <b>ssl</b> is
 + * a list that indicates that the client knows how to do the v2 TLS connection
 + * handshake. */
 +int
 +tor_tls_client_is_using_v2_ciphers(const SSL *ssl)
 +{
 +  STACK_OF(SSL_CIPHER) *ciphers;
 +#ifdef HAVE_SSL_GET_CLIENT_CIPHERS
 +  ciphers = SSL_get_client_ciphers(ssl);
 +#else
 +  SSL_SESSION *session;
 +  if (!(session = SSL_get_session((SSL *)ssl))) {
 +    log_info(LD_NET, "No session on TLS?");
 +    return CIPHERS_ERR;
 +  }
 +  ciphers = session->ciphers;
 +#endif /* defined(HAVE_SSL_GET_CLIENT_CIPHERS) */
 +
 +  return tor_tls_classify_client_ciphers(ssl, ciphers) >= CIPHERS_V2;
 +}
 +
 +/** Invoked when we're accepting a connection on <b>ssl</b>, and the connection
 + * changes state. We use this:
 + * <ul><li>To alter the state of the handshake partway through, so we
 + *         do not send or request extra certificates in v2 handshakes.</li>
 + * <li>To detect renegotiation</li></ul>
 + */
 +void
 +tor_tls_server_info_callback(const SSL *ssl, int type, int val)
 +{
 +  tor_tls_t *tls;
 +  (void) val;
 +
 +  IF_BUG_ONCE(ssl == NULL) {
 +    return; // LCOV_EXCL_LINE
 +  }
 +
 +  tor_tls_debug_state_callback(ssl, type, val);
 +
 +  if (type != SSL_CB_ACCEPT_LOOP)
 +    return;
 +
 +  OSSL_HANDSHAKE_STATE ssl_state = SSL_get_state(ssl);
 +  if (! STATE_IS_SW_SERVER_HELLO(ssl_state))
 +    return;
 +  tls = tor_tls_get_by_ssl(ssl);
 +  if (tls) {
 +    /* Check whether we're watching for renegotiates.  If so, this is one! */
 +    if (tls->negotiated_callback)
 +      tls->got_renegotiate = 1;
 +  } else {
 +    log_warn(LD_BUG, "Couldn't look up the tls for an SSL*. How odd!");
 +    return;
 +  }
 +
 +  /* Now check the cipher list. */
 +  if (tor_tls_client_is_using_v2_ciphers(ssl)) {
 +    if (tls->wasV2Handshake)
 +      return; /* We already turned this stuff off for the first handshake;
 +               * This is a renegotiation. */
 +
 +    /* Yes, we're casting away the const from ssl.  This is very naughty of us.
 +     * Let's hope openssl doesn't notice! */
 +
 +    /* Set SSL_MODE_NO_AUTO_CHAIN to keep from sending back any extra certs. */
 +    SSL_set_mode((SSL*) ssl, SSL_MODE_NO_AUTO_CHAIN);
 +    /* Don't send a hello request. */
 +    SSL_set_verify((SSL*) ssl, SSL_VERIFY_NONE, NULL);
 +
 +    if (tls) {
 +      tls->wasV2Handshake = 1;
 +    } else {
 +      /* LCOV_EXCL_START this line is not reachable */
 +      log_warn(LD_BUG, "Couldn't look up the tls for an SSL*. How odd!");
 +      /* LCOV_EXCL_STOP */
 +    }
 +  }
 +}
 +
 +/** Callback to get invoked on a server after we've read the list of ciphers
 + * the client supports, but before we pick our own ciphersuite.
 + *
 + * We can't abuse an info_cb for this, since by the time one of the
 + * client_hello info_cbs is called, we've already picked which ciphersuite to
 + * use.
 + *
 + * Technically, this function is an abuse of this callback, since the point of
 + * a session_secret_cb is to try to set up and/or verify a shared-secret for
 + * authentication on the fly.  But as long as we return 0, we won't actually be
 + * setting up a shared secret, and all will be fine.
 + */
 +int
 +tor_tls_session_secret_cb(SSL *ssl, void *secret, int *secret_len,
 +                          STACK_OF(SSL_CIPHER) *peer_ciphers,
 +                          CONST_IF_OPENSSL_1_1_API SSL_CIPHER **cipher,
 +                          void *arg)
 +{
 +  (void) secret;
 +  (void) secret_len;
 +  (void) peer_ciphers;
 +  (void) cipher;
 +  (void) arg;
 +
 +  if (tor_tls_classify_client_ciphers(ssl, peer_ciphers) ==
 +       CIPHERS_UNRESTRICTED) {
 +    SSL_set_cipher_list(ssl, UNRESTRICTED_SERVER_CIPHER_LIST);
 +  }
 +
 +  SSL_set_session_secret_cb(ssl, NULL, NULL);
 +
 +  return 0;
 +}
 +static void
 +tor_tls_setup_session_secret_cb(tor_tls_t *tls)
 +{
 +  SSL_set_session_secret_cb(tls->ssl, tor_tls_session_secret_cb, NULL);
 +}
 +
 +/** Create a new TLS object from a file descriptor, and a flag to
 + * determine whether it is functioning as a server.
 + */
 +tor_tls_t *
 +tor_tls_new(tor_socket_t sock, int isServer)
 +{
 +  BIO *bio = NULL;
 +  tor_tls_t *result = tor_malloc_zero(sizeof(tor_tls_t));
 +  tor_tls_context_t *context = tor_tls_context_get(isServer);
 +  result->magic = TOR_TLS_MAGIC;
 +
 +  check_no_tls_errors();
 +  tor_assert(context); /* make sure somebody made it first */
 +  if (!(result->ssl = SSL_new(context->ctx))) {
 +    tls_log_errors(NULL, LOG_WARN, LD_NET, "creating SSL object");
 +    tor_free(result);
 +    goto err;
 +  }
 +
 +#ifdef SSL_set_tlsext_host_name
 +  /* Browsers use the TLS hostname extension, so we should too. */
 +  if (!isServer) {
 +    char *fake_hostname = crypto_random_hostname(4,25, "www.",".com");
 +    SSL_set_tlsext_host_name(result->ssl, fake_hostname);
 +    tor_free(fake_hostname);
 +  }
 +#endif /* defined(SSL_set_tlsext_host_name) */
 +
 +  if (!SSL_set_cipher_list(result->ssl,
 +                     isServer ? SERVER_CIPHER_LIST : CLIENT_CIPHER_LIST)) {
 +    tls_log_errors(NULL, LOG_WARN, LD_NET, "setting ciphers");
 +#ifdef SSL_set_tlsext_host_name
 +    SSL_set_tlsext_host_name(result->ssl, NULL);
 +#endif
 +    SSL_free(result->ssl);
 +    tor_free(result);
 +    goto err;
 +  }
 +  result->socket = sock;
 +  bio = BIO_new_socket(sock, BIO_CLOSE);
 +  if (! bio) {
 +    tls_log_errors(NULL, LOG_WARN, LD_NET, "opening BIO");
 +#ifdef SSL_set_tlsext_host_name
 +    SSL_set_tlsext_host_name(result->ssl, NULL);
 +#endif
 +    SSL_free(result->ssl);
 +    tor_free(result);
 +    goto err;
 +  }
 +  {
 +    int set_worked =
 +      SSL_set_ex_data(result->ssl, tor_tls_object_ex_data_index, result);
 +    if (!set_worked) {
 +      log_warn(LD_BUG,
 +               "Couldn't set the tls for an SSL*; connection will fail");
 +    }
 +  }
 +  SSL_set_bio(result->ssl, bio, bio);
 +  tor_tls_context_incref(context);
 +  result->context = context;
 +  result->state = TOR_TLS_ST_HANDSHAKE;
 +  result->isServer = isServer;
 +  result->wantwrite_n = 0;
 +  result->last_write_count = (unsigned long) BIO_number_written(bio);
 +  result->last_read_count = (unsigned long) BIO_number_read(bio);
 +  if (result->last_write_count || result->last_read_count) {
 +    log_warn(LD_NET, "Newly created BIO has read count %lu, write count %lu",
 +             result->last_read_count, result->last_write_count);
 +  }
 +  if (isServer) {
 +    SSL_set_info_callback(result->ssl, tor_tls_server_info_callback);
 +  } else {
 +    SSL_set_info_callback(result->ssl, tor_tls_debug_state_callback);
 +  }
 +
 +  if (isServer)
 +    tor_tls_setup_session_secret_cb(result);
 +
 +  goto done;
 + err:
 +  result = NULL;
 + done:
 +  /* Not expected to get called. */
 +  tls_log_errors(NULL, LOG_WARN, LD_NET, "creating tor_tls_t object");
 +  return result;
 +}
 +
 +/** Set <b>cb</b> to be called with argument <b>arg</b> whenever <b>tls</b>
 + * next gets a client-side renegotiate in the middle of a read.  Do not
 + * invoke this function until <em>after</em> initial handshaking is done!
 + */
 +void
 +tor_tls_set_renegotiate_callback(tor_tls_t *tls,
 +                                 void (*cb)(tor_tls_t *, void *arg),
 +                                 void *arg)
 +{
 +  tls->negotiated_callback = cb;
 +  tls->callback_arg = arg;
 +  tls->got_renegotiate = 0;
 +  if (cb) {
 +    SSL_set_info_callback(tls->ssl, tor_tls_server_info_callback);
 +  } else {
 +    SSL_set_info_callback(tls->ssl, tor_tls_debug_state_callback);
 +  }
 +}
 +
 +/** If this version of openssl requires it, turn on renegotiation on
 + * <b>tls</b>.
 + */
 +void
 +tor_tls_unblock_renegotiation(tor_tls_t *tls)
 +{
 +  /* Yes, we know what we are doing here.  No, we do not treat a renegotiation
 +   * as authenticating any earlier-received data. */
 +  SSL_set_options(tls->ssl,
 +                  SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION);
 +}
 +
 +/** If this version of openssl supports it, turn off renegotiation on
 + * <b>tls</b>.  (Our protocol never requires this for security, but it's nice
 + * to use belt-and-suspenders here.)
 + */
 +void
 +tor_tls_block_renegotiation(tor_tls_t *tls)
 +{
 +#ifdef SUPPORT_UNSAFE_RENEGOTIATION_FLAG
 +  tls->ssl->s3->flags &= ~SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION;
 +#else
 +  (void) tls;
 +#endif
 +}
 +
 +/** Assert that the flags that allow legacy renegotiation are still set */
 +void
 +tor_tls_assert_renegotiation_unblocked(tor_tls_t *tls)
 +{
 +#if defined(SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION) && \
 +  SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION != 0
 +  long options = SSL_get_options(tls->ssl);
 +  tor_assert(0 != (options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION));
 +#else
 +  (void) tls;
 +#endif /* defined(SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION) && ... */
 +}
 +
 +/**
 + * Tell the TLS library that the underlying socket for <b>tls</b> has been
 + * closed, and the library should not attempt to free that socket itself.
 + */
 +void
 +tor_tls_release_socket(tor_tls_t *tls)
 +{
 +  if (! tls)
 +    return;
 +
 +  BIO *rbio, *wbio;
 +  rbio = SSL_get_rbio(tls->ssl);
 +  wbio = SSL_get_wbio(tls->ssl);
 +
 +  if (rbio) {
 +    (void) BIO_set_close(rbio, BIO_NOCLOSE);
 +  }
 +  if (wbio && wbio != rbio) {
 +    (void) BIO_set_close(wbio, BIO_NOCLOSE);
 +  }
 +}
 +
 +void
 +tor_tls_impl_free_(tor_tls_impl_t *ssl)
 +{
 +  if (!ssl)
 +    return;
 +
 +#ifdef SSL_set_tlsext_host_name
 +  SSL_set_tlsext_host_name(ssl, NULL);
 +#endif
 +  SSL_free(ssl);
 +}
 +
 +/** Underlying function for TLS reading.  Reads up to <b>len</b>
 + * characters from <b>tls</b> into <b>cp</b>.  On success, returns the
 + * number of characters read.  On failure, returns TOR_TLS_ERROR,
 + * TOR_TLS_CLOSE, TOR_TLS_WANTREAD, or TOR_TLS_WANTWRITE.
 + */
 +MOCK_IMPL(int,
 +tor_tls_read,(tor_tls_t *tls, char *cp, size_t len))
 +{
 +  int r, err;
 +  tor_assert(tls);
 +  tor_assert(tls->ssl);
 +  tor_assert(tls->state == TOR_TLS_ST_OPEN);
 +  tor_assert(len<INT_MAX);
 +  r = SSL_read(tls->ssl, cp, (int)len);
 +  if (r > 0) {
 +    if (tls->got_renegotiate) {
 +      /* Renegotiation happened! */
 +      log_info(LD_NET, "Got a TLS renegotiation from %s", ADDR(tls));
 +      if (tls->negotiated_callback)
 +        tls->negotiated_callback(tls, tls->callback_arg);
 +      tls->got_renegotiate = 0;
 +    }
 +    return r;
 +  }
 +  err = tor_tls_get_error(tls, r, CATCH_ZERO, "reading", LOG_DEBUG, LD_NET);
 +  if (err == TOR_TLS_ZERORETURN_ || err == TOR_TLS_CLOSE) {
 +    log_debug(LD_NET,"read returned r=%d; TLS is closed",r);
 +    tls->state = TOR_TLS_ST_CLOSED;
 +    return TOR_TLS_CLOSE;
 +  } else {
 +    tor_assert(err != TOR_TLS_DONE);
 +    log_debug(LD_NET,"read returned r=%d, err=%d",r,err);
 +    return err;
 +  }
 +}
 +
 +/** Total number of bytes that we've used TLS to send.  Used to track TLS
 + * overhead. */
 +STATIC uint64_t total_bytes_written_over_tls = 0;
 +/** Total number of bytes that TLS has put on the network for us. Used to
 + * track TLS overhead. */
 +STATIC uint64_t total_bytes_written_by_tls = 0;
 +
 +/** Underlying function for TLS writing.  Write up to <b>n</b>
 + * characters from <b>cp</b> onto <b>tls</b>.  On success, returns the
 + * number of characters written.  On failure, returns TOR_TLS_ERROR,
 + * TOR_TLS_WANTREAD, or TOR_TLS_WANTWRITE.
 + */
 +int
 +tor_tls_write(tor_tls_t *tls, const char *cp, size_t n)
 +{
 +  int r, err;
 +  tor_assert(tls);
 +  tor_assert(tls->ssl);
 +  tor_assert(tls->state == TOR_TLS_ST_OPEN);
 +  tor_assert(n < INT_MAX);
 +  if (n == 0)
 +    return 0;
 +  if (tls->wantwrite_n) {
 +    /* if WANTWRITE last time, we must use the _same_ n as before */
 +    tor_assert(n >= tls->wantwrite_n);
 +    log_debug(LD_NET,"resuming pending-write, (%d to flush, reusing %d)",
 +              (int)n, (int)tls->wantwrite_n);
 +    n = tls->wantwrite_n;
 +    tls->wantwrite_n = 0;
 +  }
 +  r = SSL_write(tls->ssl, cp, (int)n);
 +  err = tor_tls_get_error(tls, r, 0, "writing", LOG_INFO, LD_NET);
 +  if (err == TOR_TLS_DONE) {
 +    total_bytes_written_over_tls += r;
 +    return r;
 +  }
 +  if (err == TOR_TLS_WANTWRITE || err == TOR_TLS_WANTREAD) {
 +    tls->wantwrite_n = n;
 +  }
 +  return err;
 +}
 +
 +/** Perform initial handshake on <b>tls</b>.  When finished, returns
 + * TOR_TLS_DONE.  On failure, returns TOR_TLS_ERROR, TOR_TLS_WANTREAD,
 + * or TOR_TLS_WANTWRITE.
 + */
 +int
 +tor_tls_handshake(tor_tls_t *tls)
 +{
 +  int r;
 +  tor_assert(tls);
 +  tor_assert(tls->ssl);
 +  tor_assert(tls->state == TOR_TLS_ST_HANDSHAKE);
 +
 +  check_no_tls_errors();
 +
 +  OSSL_HANDSHAKE_STATE oldstate = SSL_get_state(tls->ssl);
 +
 +  if (tls->isServer) {
 +    log_debug(LD_HANDSHAKE, "About to call SSL_accept on %p (%s)", tls,
 +              SSL_state_string_long(tls->ssl));
 +    r = SSL_accept(tls->ssl);
 +  } else {
 +    log_debug(LD_HANDSHAKE, "About to call SSL_connect on %p (%s)", tls,
 +              SSL_state_string_long(tls->ssl));
 +    r = SSL_connect(tls->ssl);
 +  }
 +
 +  OSSL_HANDSHAKE_STATE newstate = SSL_get_state(tls->ssl);
 +
 +  if (oldstate != newstate)
 +    log_debug(LD_HANDSHAKE, "After call, %p was in state %s",
 +              tls, SSL_state_string_long(tls->ssl));
 +  /* We need to call this here and not earlier, since OpenSSL has a penchant
 +   * for clearing its flags when you say accept or connect. */
 +  tor_tls_unblock_renegotiation(tls);
 +  r = tor_tls_get_error(tls,r,0, "handshaking", LOG_INFO, LD_HANDSHAKE);
 +  if (ERR_peek_error() != 0) {
 +    tls_log_errors(tls, tls->isServer ? LOG_INFO : LOG_WARN, LD_HANDSHAKE,
 +                   "handshaking");
 +    return TOR_TLS_ERROR_MISC;
 +  }
 +  if (r == TOR_TLS_DONE) {
 +    tls->state = TOR_TLS_ST_OPEN;
 +    return tor_tls_finish_handshake(tls);
 +  }
 +  return r;
 +}
 +
 +/** Perform the final part of the initial TLS handshake on <b>tls</b>.  This
 + * should be called for the first handshake only: it determines whether the v1
 + * or the v2 handshake was used, and adjusts things for the renegotiation
 + * handshake as appropriate.
 + *
 + * tor_tls_handshake() calls this on its own; you only need to call this if
 + * bufferevent is doing the handshake for you.
 + */
 +int
 +tor_tls_finish_handshake(tor_tls_t *tls)
 +{
 +  int r = TOR_TLS_DONE;
 +  check_no_tls_errors();
 +  if (tls->isServer) {
 +    SSL_set_info_callback(tls->ssl, NULL);
 +    SSL_set_verify(tls->ssl, SSL_VERIFY_PEER, always_accept_verify_cb);
 +    SSL_clear_mode(tls->ssl, SSL_MODE_NO_AUTO_CHAIN);
 +    if (tor_tls_client_is_using_v2_ciphers(tls->ssl)) {
 +      /* This check is redundant, but back when we did it in the callback,
 +       * we might have not been able to look up the tor_tls_t if the code
 +       * was buggy.  Fixing that. */
 +      if (!tls->wasV2Handshake) {
 +        log_warn(LD_BUG, "For some reason, wasV2Handshake didn't"
 +                 " get set. Fixing that.");
 +      }
 +      tls->wasV2Handshake = 1;
 +      log_debug(LD_HANDSHAKE, "Completed V2 TLS handshake with client; waiting"
 +                " for renegotiation.");
 +    } else {
 +      tls->wasV2Handshake = 0;
 +    }
 +  } else {
 +    /* Client-side */
 +    tls->wasV2Handshake = 1;
 +    /* XXXX this can move, probably? -NM */
 +    if (SSL_set_cipher_list(tls->ssl, SERVER_CIPHER_LIST) == 0) {
 +      tls_log_errors(NULL, LOG_WARN, LD_HANDSHAKE, "re-setting ciphers");
 +      r = TOR_TLS_ERROR_MISC;
 +    }
 +  }
 +  tls_log_errors(NULL, LOG_WARN, LD_NET, "finishing the handshake");
 +  return r;
 +}
 +
 +/** Return true iff this TLS connection is authenticated.
 + */
 +int
 +tor_tls_peer_has_cert(tor_tls_t *tls)
 +{
 +  X509 *cert;
 +  cert = SSL_get_peer_certificate(tls->ssl);
 +  tls_log_errors(tls, LOG_WARN, LD_HANDSHAKE, "getting peer certificate");
 +  if (!cert)
 +    return 0;
 +  X509_free(cert);
 +  return 1;
 +}
 +
 +/** Return a newly allocated copy of the peer certificate, or NULL if there
 + * isn't one. */
 +MOCK_IMPL(tor_x509_cert_t *,
 +tor_tls_get_peer_cert,(tor_tls_t *tls))
 +{
 +  X509 *cert;
 +  cert = SSL_get_peer_certificate(tls->ssl);
 +  tls_log_errors(tls, LOG_WARN, LD_HANDSHAKE, "getting peer certificate");
 +  if (!cert)
 +    return NULL;
 +  return tor_x509_cert_new(cert);
 +}
 +
 +/** Return a newly allocated copy of the cerficate we used on the connection,
 + * or NULL if somehow we didn't use one. */
 +MOCK_IMPL(tor_x509_cert_t *,
 +tor_tls_get_own_cert,(tor_tls_t *tls))
 +{
 +  X509 *cert = SSL_get_certificate(tls->ssl);
 +  tls_log_errors(tls, LOG_WARN, LD_HANDSHAKE,
 +                 "getting own-connection certificate");
 +  if (!cert)
 +    return NULL;
 +  /* Fun inconsistency: SSL_get_peer_certificate increments the reference
 +   * count, but SSL_get_certificate does not. */
 +  X509 *duplicate = X509_dup(cert);
 +  if (BUG(duplicate == NULL))
 +    return NULL;
 +  return tor_x509_cert_new(duplicate);
 +}
 +
 +/** Helper function: try to extract a link certificate and an identity
 + * certificate from <b>tls</b>, and store them in *<b>cert_out</b> and
 + * *<b>id_cert_out</b> respectively.  Log all messages at level
 + * <b>severity</b>.
 + *
 + * Note that a reference is added both of the returned certificates. */
 +MOCK_IMPL(void,
 +try_to_extract_certs_from_tls,(int severity, tor_tls_t *tls,
 +                               X509 **cert_out, X509 **id_cert_out))
 +{
 +  X509 *cert = NULL, *id_cert = NULL;
 +  STACK_OF(X509) *chain = NULL;
 +  int num_in_chain, i;
 +  *cert_out = *id_cert_out = NULL;
 +  if (!(cert = SSL_get_peer_certificate(tls->ssl)))
 +    return;
 +  *cert_out = cert;
 +  if (!(chain = SSL_get_peer_cert_chain(tls->ssl)))
 +    return;
 +  num_in_chain = sk_X509_num(chain);
 +  /* 1 means we're receiving (server-side), and it's just the id_cert.
 +   * 2 means we're connecting (client-side), and it's both the link
 +   * cert and the id_cert.
 +   */
 +  if (num_in_chain < 1) {
 +    log_fn(severity,LD_PROTOCOL,
 +           "Unexpected number of certificates in chain (%d)",
 +           num_in_chain);
 +    return;
 +  }
 +  for (i=0; i<num_in_chain; ++i) {
 +    id_cert = sk_X509_value(chain, i);
 +    if (X509_cmp(id_cert, cert) != 0)
 +      break;
 +  }
 +  *id_cert_out = id_cert ? X509_dup(id_cert) : NULL;
 +}
 +
 +/** Return the number of bytes available for reading from <b>tls</b>.
 + */
 +int
 +tor_tls_get_pending_bytes(tor_tls_t *tls)
 +{
 +  tor_assert(tls);
 +  return SSL_pending(tls->ssl);
 +}
 +
 +/** If <b>tls</b> requires that the next write be of a particular size,
 + * return that size.  Otherwise, return 0. */
 +size_t
 +tor_tls_get_forced_write_size(tor_tls_t *tls)
 +{
 +  return tls->wantwrite_n;
 +}
 +
 +/** Sets n_read and n_written to the number of bytes read and written,
 + * respectively, on the raw socket used by <b>tls</b> since the last time this
 + * function was called on <b>tls</b>. */
 +void
 +tor_tls_get_n_raw_bytes(tor_tls_t *tls, size_t *n_read, size_t *n_written)
 +{
 +  BIO *wbio, *tmpbio;
 +  unsigned long r, w;
 +  r = (unsigned long) BIO_number_read(SSL_get_rbio(tls->ssl));
 +  /* We want the number of bytes actually for real written.  Unfortunately,
 +   * sometimes OpenSSL replaces the wbio on tls->ssl with a buffering bio,
 +   * which makes the answer turn out wrong.  Let's cope with that.  Note
 +   * that this approach will fail if we ever replace tls->ssl's BIOs with
 +   * buffering bios for reasons of our own.  As an alternative, we could
 +   * save the original BIO for  tls->ssl in the tor_tls_t structure, but
 +   * that would be tempting fate. */
 +  wbio = SSL_get_wbio(tls->ssl);
 +#if OPENSSL_VERSION_NUMBER >= OPENSSL_VER(1,1,0,0,5)
 +  /* BIO structure is opaque as of OpenSSL 1.1.0-pre5-dev.  Again, not
 +   * supposed to use this form of the version macro, but the OpenSSL developers
 +   * introduced major API changes in the pre-release stage.
 +   */
 +  if (BIO_method_type(wbio) == BIO_TYPE_BUFFER &&
 +        (tmpbio = BIO_next(wbio)) != NULL)
 +    wbio = tmpbio;
 +#else /* !(OPENSSL_VERSION_NUMBER >= OPENSSL_VER(1,1,0,0,5)) */
 +  if (wbio->method == BIO_f_buffer() && (tmpbio = BIO_next(wbio)) != NULL)
 +    wbio = tmpbio;
 +#endif /* OPENSSL_VERSION_NUMBER >= OPENSSL_VER(1,1,0,0,5) */
 +  w = (unsigned long) BIO_number_written(wbio);
 +
 +  /* We are ok with letting these unsigned ints go "negative" here:
 +   * If we wrapped around, this should still give us the right answer, unless
 +   * we wrapped around by more than ULONG_MAX since the last time we called
 +   * this function.
 +   */
 +  *n_read = (size_t)(r - tls->last_read_count);
 +  *n_written = (size_t)(w - tls->last_write_count);
 +  if (*n_read > INT_MAX || *n_written > INT_MAX) {
 +    log_warn(LD_BUG, "Preposterously large value in tor_tls_get_n_raw_bytes. "
 +             "r=%lu, last_read=%lu, w=%lu, last_written=%lu",
 +             r, tls->last_read_count, w, tls->last_write_count);
 +  }
 +  total_bytes_written_by_tls += *n_written;
 +  tls->last_read_count = r;
 +  tls->last_write_count = w;
 +}
 +
 +/** Return a ratio of the bytes that TLS has sent to the bytes that we've told
 + * it to send. Used to track whether our TLS records are getting too tiny. */
 +MOCK_IMPL(double,
 +tls_get_write_overhead_ratio,(void))
 +{
 +  if (total_bytes_written_over_tls == 0)
 +    return 1.0;
 +
 +  return ((double)total_bytes_written_by_tls) /
 +    ((double)total_bytes_written_over_tls);
 +}
 +
 +/** Implement check_no_tls_errors: If there are any pending OpenSSL
 + * errors, log an error message. */
 +void
 +check_no_tls_errors_(const char *fname, int line)
 +{
 +  if (ERR_peek_error() == 0)
 +    return;
 +  log_warn(LD_CRYPTO, "Unhandled OpenSSL errors found at %s:%d: ",
 +      tor_fix_source_file(fname), line);
 +  tls_log_errors(NULL, LOG_WARN, LD_NET, NULL);
 +}
 +
 +/** Return true iff the initial TLS connection at <b>tls</b> did not use a v2
 + * TLS handshake. Output is undefined if the handshake isn't finished. */
 +int
 +tor_tls_used_v1_handshake(tor_tls_t *tls)
 +{
 +  return ! tls->wasV2Handshake;
 +}
 +
 +/** Return true iff the server TLS connection <b>tls</b> got the renegotiation
 + * request it was waiting for. */
 +int
 +tor_tls_server_got_renegotiate(tor_tls_t *tls)
 +{
 +  return tls->got_renegotiate;
 +}
 +
 +#ifndef HAVE_SSL_GET_CLIENT_RANDOM
 +static size_t
 +SSL_get_client_random(SSL *s, uint8_t *out, size_t len)
 +{
 +  if (len == 0)
 +    return SSL3_RANDOM_SIZE;
 +  tor_assert(len == SSL3_RANDOM_SIZE);
 +  tor_assert(s->s3);
 +  memcpy(out, s->s3->client_random, len);
 +  return len;
 +}
 +#endif /* !defined(HAVE_SSL_GET_CLIENT_RANDOM) */
 +
 +#ifndef HAVE_SSL_GET_SERVER_RANDOM
 +static size_t
 +SSL_get_server_random(SSL *s, uint8_t *out, size_t len)
 +{
 +  if (len == 0)
 +    return SSL3_RANDOM_SIZE;
 +  tor_assert(len == SSL3_RANDOM_SIZE);
 +  tor_assert(s->s3);
 +  memcpy(out, s->s3->server_random, len);
 +  return len;
 +}
 +#endif /* !defined(HAVE_SSL_GET_SERVER_RANDOM) */
 +
 +#ifndef HAVE_SSL_SESSION_GET_MASTER_KEY
 +size_t
 +SSL_SESSION_get_master_key(SSL_SESSION *s, uint8_t *out, size_t len)
 +{
 +  tor_assert(s);
 +  if (len == 0)
 +    return s->master_key_length;
 +  tor_assert(len == (size_t)s->master_key_length);
 +  tor_assert(out);
 +  memcpy(out, s->master_key, len);
 +  return len;
 +}
 +#endif /* !defined(HAVE_SSL_SESSION_GET_MASTER_KEY) */
 +
 +/** Set the DIGEST256_LEN buffer at <b>secrets_out</b> to the value used in
 + * the v3 handshake to prove that the client knows the TLS secrets for the
 + * connection <b>tls</b>.  Return 0 on success, -1 on failure.
 + */
 +MOCK_IMPL(int,
 +tor_tls_get_tlssecrets,(tor_tls_t *tls, uint8_t *secrets_out))
 +{
 +#define TLSSECRET_MAGIC "Tor V3 handshake TLS cross-certification"
 +  uint8_t buf[128];
 +  size_t len;
 +  tor_assert(tls);
 +
 +  SSL *const ssl = tls->ssl;
 +  SSL_SESSION *const session = SSL_get_session(ssl);
 +
 +  tor_assert(ssl);
 +  tor_assert(session);
 +
 +  const size_t server_random_len = SSL_get_server_random(ssl, NULL, 0);
 +  const size_t client_random_len = SSL_get_client_random(ssl, NULL, 0);
 +  const size_t master_key_len = SSL_SESSION_get_master_key(session, NULL, 0);
 +
 +  tor_assert(server_random_len);
 +  tor_assert(client_random_len);
 +  tor_assert(master_key_len);
 +
 +  len = client_random_len + server_random_len + strlen(TLSSECRET_MAGIC) + 1;
 +  tor_assert(len <= sizeof(buf));
 +
 +  {
 +    size_t r = SSL_get_client_random(ssl, buf, client_random_len);
 +    tor_assert(r == client_random_len);
 +  }
 +
 +  {
 +    size_t r = SSL_get_server_random(ssl,
 +                                     buf+client_random_len,
 +                                     server_random_len);
 +    tor_assert(r == server_random_len);
 +  }
 +
 +  uint8_t *master_key = tor_malloc_zero(master_key_len);
 +  {
 +    size_t r = SSL_SESSION_get_master_key(session, master_key, master_key_len);
 +    tor_assert(r == master_key_len);
 +  }
 +
 +  uint8_t *nextbuf = buf + client_random_len + server_random_len;
 +  memcpy(nextbuf, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1);
 +
 +  /*
 +    The value is an HMAC, using the TLS master key as the HMAC key, of
 +    client_random | server_random | TLSSECRET_MAGIC
 +  */
 +  crypto_hmac_sha256((char*)secrets_out,
 +                     (char*)master_key,
 +                     master_key_len,
 +                     (char*)buf, len);
 +  memwipe(buf, 0, sizeof(buf));
 +  memwipe(master_key, 0, master_key_len);
 +  tor_free(master_key);
 +
 +  return 0;
 +}
 +
 +/** Using the RFC5705 key material exporting construction, and the
 + * provided <b>context</b> (<b>context_len</b> bytes long) and
 + * <b>label</b> (a NUL-terminated string), compute a 32-byte secret in
 + * <b>secrets_out</b> that only the parties to this TLS session can
 + * compute.  Return 0 on success and -1 on failure.
 + */
 +MOCK_IMPL(int,
 +tor_tls_export_key_material,(tor_tls_t *tls, uint8_t *secrets_out,
 +                             const uint8_t *context,
 +                             size_t context_len,
 +                             const char *label))
 +{
 +  tor_assert(tls);
 +  tor_assert(tls->ssl);
 +
 +  int r = SSL_export_keying_material(tls->ssl,
 +                                     secrets_out, DIGEST256_LEN,
 +                                     label, strlen(label),
 +                                     context, context_len, 1);
 +  return (r == 1) ? 0 : -1;
 +}
 +
 +/** Examine the amount of memory used and available for buffers in <b>tls</b>.
 + * Set *<b>rbuf_capacity</b> to the amount of storage allocated for the read
 + * buffer and *<b>rbuf_bytes</b> to the amount actually used.
 + * Set *<b>wbuf_capacity</b> to the amount of storage allocated for the write
 + * buffer and *<b>wbuf_bytes</b> to the amount actually used.
 + *
 + * Return 0 on success, -1 on failure.*/
 +int
 +tor_tls_get_buffer_sizes(tor_tls_t *tls,
 +                         size_t *rbuf_capacity, size_t *rbuf_bytes,
 +                         size_t *wbuf_capacity, size_t *wbuf_bytes)
 +{
 +#if OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,1,0)
 +  (void)tls;
 +  (void)rbuf_capacity;
 +  (void)rbuf_bytes;
 +  (void)wbuf_capacity;
 +  (void)wbuf_bytes;
 +
 +  return -1;
 +#else /* !(OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,1,0)) */
 +  if (tls->ssl->s3->rbuf.buf)
 +    *rbuf_capacity = tls->ssl->s3->rbuf.len;
 +  else
 +    *rbuf_capacity = 0;
 +  if (tls->ssl->s3->wbuf.buf)
 +    *wbuf_capacity = tls->ssl->s3->wbuf.len;
 +  else
 +    *wbuf_capacity = 0;
 +  *rbuf_bytes = tls->ssl->s3->rbuf.left;
 +  *wbuf_bytes = tls->ssl->s3->wbuf.left;
 +  return 0;
 +#endif /* OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,1,0) */
 +}
 +
 +/** Check whether the ECC group requested is supported by the current OpenSSL
 + * library instance.  Return 1 if the group is supported, and 0 if not.
 + */
 +int
 +evaluate_ecgroup_for_tls(const char *ecgroup)
 +{
 +  EC_KEY *ec_key;
 +  int nid;
 +  int ret;
 +
 +  if (!ecgroup)
 +    nid = NID_tor_default_ecdhe_group;
 +  else if (!strcasecmp(ecgroup, "P256"))
 +    nid = NID_X9_62_prime256v1;
 +  else if (!strcasecmp(ecgroup, "P224"))
 +    nid = NID_secp224r1;
 +  else
 +    return 0;
 +
 +  ec_key = EC_KEY_new_by_curve_name(nid);
 +  ret = (ec_key != NULL);
 +  EC_KEY_free(ec_key);
 +
 +  return ret;
 +}



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