openssl: remove the BACKEND define kludge

Use a proper variable instead to make it easier to use a debugger and
read the code.

1 files changed, 113 insertions, 107 deletions

diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index 1d09cadca..ece655133 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -228,8 +228,6 @@ struct ssl_backend_data {
 #endif
 };
 
-#define BACKEND connssl->backend
-
 /*
  * Number of bytes to read from the random number seed file. This must be
  * a finite value (because some entropy "files" like /dev/urandom have
@@ -1269,19 +1267,19 @@ static struct curl_slist *Curl_ossl_engines_list(struct Curl_easy *data)
   return list;
 }
 
-
 static void ossl_close(struct ssl_connect_data *connssl)
 {
-  if(BACKEND->handle) {
-    (void)SSL_shutdown(BACKEND->handle);
-    SSL_set_connect_state(BACKEND->handle);
+  struct ssl_backend_data *backend = connssl->backend;
+  if(backend->handle) {
+    (void)SSL_shutdown(backend->handle);
+    SSL_set_connect_state(backend->handle);
 
-    SSL_free(BACKEND->handle);
-    BACKEND->handle = NULL;
+    SSL_free(backend->handle);
+    backend->handle = NULL;
   }
-  if(BACKEND->ctx) {
-    SSL_CTX_free(BACKEND->ctx);
-    BACKEND->ctx = NULL;
+  if(backend->ctx) {
+    SSL_CTX_free(backend->ctx);
+    backend->ctx = NULL;
   }
 }
 
@@ -1310,6 +1308,7 @@ static int Curl_ossl_shutdown(struct connectdata *conn, int sockindex)
   int buffsize;
   int err;
   bool done = FALSE;
+  struct ssl_backend_data *backend = connssl->backend;
 
 #ifndef CURL_DISABLE_FTP
   /* This has only been tested on the proftpd server, and the mod_tls code
@@ -1318,10 +1317,10 @@ static int Curl_ossl_shutdown(struct connectdata *conn, int sockindex)
      we do not send one. Let's hope other servers do the same... */
 
   if(data->set.ftp_ccc == CURLFTPSSL_CCC_ACTIVE)
-      (void)SSL_shutdown(BACKEND->handle);
+      (void)SSL_shutdown(backend->handle);
 #endif
 
-  if(BACKEND->handle) {
+  if(backend->handle) {
     buffsize = (int)sizeof(buf);
     while(!done) {
       int what = SOCKET_READABLE(conn->sock[sockindex],
@@ -1331,8 +1330,8 @@ static int Curl_ossl_shutdown(struct connectdata *conn, int sockindex)
 
         /* Something to read, let's do it and hope that it is the close
            notify alert from the server */
-        nread = (ssize_t)SSL_read(BACKEND->handle, buf, buffsize);
-        err = SSL_get_error(BACKEND->handle, (int)nread);
+        nread = (ssize_t)SSL_read(backend->handle, buf, buffsize);
+        err = SSL_get_error(backend->handle, (int)nread);
 
         switch(err) {
         case SSL_ERROR_NONE: /* this is not an error */
@@ -1377,7 +1376,7 @@ static int Curl_ossl_shutdown(struct connectdata *conn, int sockindex)
 
     if(data->set.verbose) {
 #ifdef HAVE_SSL_GET_SHUTDOWN
-      switch(SSL_get_shutdown(BACKEND->handle)) {
+      switch(SSL_get_shutdown(backend->handle)) {
       case SSL_SENT_SHUTDOWN:
         infof(data, "SSL_get_shutdown() returned SSL_SENT_SHUTDOWN\n");
         break;
@@ -1392,8 +1391,8 @@ static int Curl_ossl_shutdown(struct connectdata *conn, int sockindex)
 #endif
     }
 
-    SSL_free(BACKEND->handle);
-    BACKEND->handle = NULL;
+    SSL_free(backend->handle);
+    backend->handle = NULL;
   }
   return retval;
 }
@@ -1712,13 +1711,13 @@ static CURLcode verifystatus(struct connectdata *conn,
   const unsigned char *p;
   CURLcode result = CURLE_OK;
   struct Curl_easy *data = conn->data;
-
   OCSP_RESPONSE *rsp = NULL;
   OCSP_BASICRESP *br = NULL;
   X509_STORE     *st = NULL;
   STACK_OF(X509) *ch = NULL;
+  struct ssl_backend_data *backend = connssl->backend;
 
-  long len = SSL_get_tlsext_status_ocsp_resp(BACKEND->handle, &status);
+  long len = SSL_get_tlsext_status_ocsp_resp(backend->handle, &status);
 
   if(!status) {
     failf(data, "No OCSP response received");
@@ -1748,8 +1747,8 @@ static CURLcode verifystatus(struct connectdata *conn,
     goto end;
   }
 
-  ch = SSL_get_peer_cert_chain(BACKEND->handle);
-  st = SSL_CTX_get_cert_store(BACKEND->ctx);
+  ch = SSL_get_peer_cert_chain(backend->handle);
+  st = SSL_CTX_get_cert_store(backend->ctx);
 
 #if ((OPENSSL_VERSION_NUMBER <= 0x1000201fL) /* Fixed after 1.0.2a */ || \
      (defined(LIBRESSL_VERSION_NUMBER) &&                               \
@@ -2270,7 +2269,7 @@ set_ssl_version_min_max_legacy(ctx_option_t *ctx_options,
 #ifdef TLS1_3_VERSION
     {
       struct ssl_connect_data *connssl = &conn->ssl[sockindex];
-      SSL_CTX_set_max_proto_version(BACKEND->ctx, TLS1_3_VERSION);
+      SSL_CTX_set_max_proto_version(backend->ctx, TLS1_3_VERSION);
       *ctx_options |= SSL_OP_NO_TLSv1_2;
     }
 #else
@@ -2419,6 +2418,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   const bool verifypeer = SSL_CONN_CONFIG(verifypeer);
   const char * const ssl_crlfile = SSL_SET_OPTION(CRLfile);
   char error_buffer[256];
+  struct ssl_backend_data *backend = connssl->backend;
 
   DEBUGASSERT(ssl_connect_1 == connssl->connecting_state);
 
@@ -2477,25 +2477,25 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     return CURLE_SSL_CONNECT_ERROR;
   }
 
-  if(BACKEND->ctx)
-    SSL_CTX_free(BACKEND->ctx);
-  BACKEND->ctx = SSL_CTX_new(req_method);
+  if(backend->ctx)
+    SSL_CTX_free(backend->ctx);
+  backend->ctx = SSL_CTX_new(req_method);
 
-  if(!BACKEND->ctx) {
+  if(!backend->ctx) {
     failf(data, "SSL: couldn't create a context: %s",
           ossl_strerror(ERR_peek_error(), error_buffer, sizeof(error_buffer)));
     return CURLE_OUT_OF_MEMORY;
   }
 
 #ifdef SSL_MODE_RELEASE_BUFFERS
-  SSL_CTX_set_mode(BACKEND->ctx, SSL_MODE_RELEASE_BUFFERS);
+  SSL_CTX_set_mode(backend->ctx, SSL_MODE_RELEASE_BUFFERS);
 #endif
 
 #ifdef SSL_CTRL_SET_MSG_CALLBACK
   if(data->set.fdebug && data->set.verbose) {
     /* the SSL trace callback is only used for verbose logging */
-    SSL_CTX_set_msg_callback(BACKEND->ctx, ssl_tls_trace);
-    SSL_CTX_set_msg_callback_arg(BACKEND->ctx, conn);
+    SSL_CTX_set_msg_callback(backend->ctx, ssl_tls_trace);
+    SSL_CTX_set_msg_callback_arg(backend->ctx, conn);
   }
 #endif
 
@@ -2561,8 +2561,8 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     /* "--sslv2" option means SSLv2 only, disable all others */
     case CURL_SSLVERSION_SSLv2:
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L /* 1.1.0 */
-      SSL_CTX_set_min_proto_version(BACKEND->ctx, SSL2_VERSION);
-      SSL_CTX_set_max_proto_version(BACKEND->ctx, SSL2_VERSION);
+      SSL_CTX_set_min_proto_version(backend->ctx, SSL2_VERSION);
+      SSL_CTX_set_max_proto_version(backend->ctx, SSL2_VERSION);
 #else
       ctx_options |= SSL_OP_NO_SSLv3;
       ctx_options |= SSL_OP_NO_TLSv1;
@@ -2579,8 +2579,8 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     /* "--sslv3" option means SSLv3 only, disable all others */
     case CURL_SSLVERSION_SSLv3:
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L /* 1.1.0 */
-      SSL_CTX_set_min_proto_version(BACKEND->ctx, SSL3_VERSION);
-      SSL_CTX_set_max_proto_version(BACKEND->ctx, SSL3_VERSION);
+      SSL_CTX_set_min_proto_version(backend->ctx, SSL3_VERSION);
+      SSL_CTX_set_max_proto_version(backend->ctx, SSL3_VERSION);
 #else
       ctx_options |= SSL_OP_NO_SSLv2;
       ctx_options |= SSL_OP_NO_TLSv1;
@@ -2607,7 +2607,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
       ctx_options |= SSL_OP_NO_SSLv3;
 
 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) /* 1.1.0 */
-      result = set_ssl_version_min_max(BACKEND->ctx, conn);
+      result = set_ssl_version_min_max(backend->ctx, conn);
 #else
       result = set_ssl_version_min_max_legacy(&ctx_options, conn, sockindex);
 #endif
@@ -2620,11 +2620,11 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
       return CURLE_SSL_CONNECT_ERROR;
   }
 
-  SSL_CTX_set_options(BACKEND->ctx, ctx_options);
+  SSL_CTX_set_options(backend->ctx, ctx_options);
 
 #ifdef HAS_NPN
   if(conn->bits.tls_enable_npn)
-    SSL_CTX_set_next_proto_select_cb(BACKEND->ctx, select_next_proto_cb, conn);
+    SSL_CTX_set_next_proto_select_cb(backend->ctx, select_next_proto_cb, conn);
 #endif
 
 #ifdef HAS_ALPN
@@ -2652,12 +2652,12 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     /* expects length prefixed preference ordered list of protocols in wire
      * format
      */
-    SSL_CTX_set_alpn_protos(BACKEND->ctx, protocols, cur);
+    SSL_CTX_set_alpn_protos(backend->ctx, protocols, cur);
   }
 #endif
 
   if(ssl_cert || ssl_cert_type) {
-    if(!cert_stuff(conn, BACKEND->ctx, ssl_cert, ssl_cert_type,
+    if(!cert_stuff(conn, backend->ctx, ssl_cert, ssl_cert_type,
                    SSL_SET_OPTION(key), SSL_SET_OPTION(key_type),
                    SSL_SET_OPTION(key_passwd))) {
       /* failf() is already done in cert_stuff() */
@@ -2669,7 +2669,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   if(!ciphers)
     ciphers = (char *)DEFAULT_CIPHER_SELECTION;
   if(ciphers) {
-    if(!SSL_CTX_set_cipher_list(BACKEND->ctx, ciphers)) {
+    if(!SSL_CTX_set_cipher_list(backend->ctx, ciphers)) {
       failf(data, "failed setting cipher list: %s", ciphers);
       return CURLE_SSL_CIPHER;
     }
@@ -2680,7 +2680,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   {
     char *ciphers13 = SSL_CONN_CONFIG(cipher_list13);
     if(ciphers13) {
-      if(!SSL_CTX_set_ciphersuites(BACKEND->ctx, ciphers13)) {
+      if(!SSL_CTX_set_ciphersuites(backend->ctx, ciphers13)) {
         failf(data, "failed setting TLS 1.3 cipher suite: %s", ciphers13);
         return CURLE_SSL_CIPHER;
       }
@@ -2691,7 +2691,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
 
 #ifdef HAVE_SSL_CTX_SET_POST_HANDSHAKE_AUTH
   /* OpenSSL 1.1.1 requires clients to opt-in for PHA */
-  SSL_CTX_set_post_handshake_auth(BACKEND->ctx, 1);
+  SSL_CTX_set_post_handshake_auth(backend->ctx, 1);
 #endif
 
 #ifdef USE_TLS_SRP
@@ -2700,18 +2700,18 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
 
     infof(data, "Using TLS-SRP username: %s\n", ssl_username);
 
-    if(!SSL_CTX_set_srp_username(BACKEND->ctx, ssl_username)) {
+    if(!SSL_CTX_set_srp_username(backend->ctx, ssl_username)) {
       failf(data, "Unable to set SRP user name");
       return CURLE_BAD_FUNCTION_ARGUMENT;
     }
-    if(!SSL_CTX_set_srp_password(BACKEND->ctx, SSL_SET_OPTION(password))) {
+    if(!SSL_CTX_set_srp_password(backend->ctx, SSL_SET_OPTION(password))) {
       failf(data, "failed setting SRP password");
       return CURLE_BAD_FUNCTION_ARGUMENT;
     }
     if(!SSL_CONN_CONFIG(cipher_list)) {
       infof(data, "Setting cipher list SRP\n");
 
-      if(!SSL_CTX_set_cipher_list(BACKEND->ctx, "SRP")) {
+      if(!SSL_CTX_set_cipher_list(backend->ctx, "SRP")) {
         failf(data, "failed setting SRP cipher list");
         return CURLE_SSL_CIPHER;
       }
@@ -2722,7 +2722,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   if(ssl_cafile || ssl_capath) {
     /* tell SSL where to find CA certificates that are used to verify
        the servers certificate. */
-    if(!SSL_CTX_load_verify_locations(BACKEND->ctx, ssl_cafile, ssl_capath)) {
+    if(!SSL_CTX_load_verify_locations(backend->ctx, ssl_cafile, ssl_capath)) {
       if(verifypeer) {
         /* Fail if we insist on successfully verifying the server. */
         failf(data, "error setting certificate verify locations:\n"
@@ -2750,14 +2750,14 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   else if(verifypeer) {
     /* verifying the peer without any CA certificates won't
        work so use openssl's built in default as fallback */
-    SSL_CTX_set_default_verify_paths(BACKEND->ctx);
+    SSL_CTX_set_default_verify_paths(backend->ctx);
   }
 #endif
 
   if(ssl_crlfile) {
     /* tell SSL where to find CRL file that is used to check certificate
      * revocation */
-    lookup = X509_STORE_add_lookup(SSL_CTX_get_cert_store(BACKEND->ctx),
+    lookup = X509_STORE_add_lookup(SSL_CTX_get_cert_store(backend->ctx),
                                  X509_LOOKUP_file());
     if(!lookup ||
        (!X509_load_crl_file(lookup, ssl_crlfile, X509_FILETYPE_PEM)) ) {
@@ -2766,7 +2766,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     }
     /* Everything is fine. */
     infof(data, "successfully load CRL file:\n");
-    X509_STORE_set_flags(SSL_CTX_get_cert_store(BACKEND->ctx),
+    X509_STORE_set_flags(SSL_CTX_get_cert_store(backend->ctx),
                          X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
 
     infof(data, "  CRLfile: %s\n", ssl_crlfile);
@@ -2781,7 +2781,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
        https://rt.openssl.org/Ticket/Display.html?id=3621&user=guest&pass=guest
     */
 #if defined(X509_V_FLAG_TRUSTED_FIRST) && !defined(X509_V_FLAG_NO_ALT_CHAINS)
-    X509_STORE_set_flags(SSL_CTX_get_cert_store(BACKEND->ctx),
+    X509_STORE_set_flags(SSL_CTX_get_cert_store(backend->ctx),
                          X509_V_FLAG_TRUSTED_FIRST);
 #endif
 #ifdef X509_V_FLAG_PARTIAL_CHAIN
@@ -2790,7 +2790,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
          trust-anchors, in the same way as self-signed root CA certificates
          are. This allows users to verify servers using the intermediate cert
          only, instead of needing the whole chain. */
-      X509_STORE_set_flags(SSL_CTX_get_cert_store(BACKEND->ctx),
+      X509_STORE_set_flags(SSL_CTX_get_cert_store(backend->ctx),
                            X509_V_FLAG_PARTIAL_CHAIN);
     }
 #endif
@@ -2800,13 +2800,13 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
    * fail to connect if the verification fails, or if it should continue
    * anyway. In the latter case the result of the verification is checked with
    * SSL_get_verify_result() below. */
-  SSL_CTX_set_verify(BACKEND->ctx,
+  SSL_CTX_set_verify(backend->ctx,
                      verifypeer ? SSL_VERIFY_PEER : SSL_VERIFY_NONE, NULL);
 
   /* Enable logging of secrets to the file specified in env SSLKEYLOGFILE. */
 #if defined(ENABLE_SSLKEYLOGFILE) && defined(HAVE_KEYLOG_CALLBACK)
   if(keylog_file_fp) {
-    SSL_CTX_set_keylog_callback(BACKEND->ctx, ossl_keylog_callback);
+    SSL_CTX_set_keylog_callback(backend->ctx, ossl_keylog_callback);
   }
 #endif
 
@@ -2814,14 +2814,14 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
    * callback. Use the "external storage" mode to avoid that OpenSSL creates
    * an internal session cache.
    */
-  SSL_CTX_set_session_cache_mode(BACKEND->ctx,
+  SSL_CTX_set_session_cache_mode(backend->ctx,
       SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_INTERNAL);
-  SSL_CTX_sess_set_new_cb(BACKEND->ctx, ossl_new_session_cb);
+  SSL_CTX_sess_set_new_cb(backend->ctx, ossl_new_session_cb);
 
   /* give application a chance to interfere with SSL set up. */
   if(data->set.ssl.fsslctx) {
     Curl_set_in_callback(data, true);
-    result = (*data->set.ssl.fsslctx)(data, BACKEND->ctx,
+    result = (*data->set.ssl.fsslctx)(data, backend->ctx,
                                       data->set.ssl.fsslctxp);
     Curl_set_in_callback(data, false);
     if(result) {
@@ -2831,10 +2831,10 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   }
 
   /* Lets make an SSL structure */
-  if(BACKEND->handle)
-    SSL_free(BACKEND->handle);
-  BACKEND->handle = SSL_new(BACKEND->ctx);
-  if(!BACKEND->handle) {
+  if(backend->handle)
+    SSL_free(backend->handle);
+  backend->handle = SSL_new(backend->ctx);
+  if(!backend->handle) {
     failf(data, "SSL: couldn't create a context (handle)!");
     return CURLE_OUT_OF_MEMORY;
   }
@@ -2842,23 +2842,23 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
 #if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_TLSEXT) && \
     !defined(OPENSSL_NO_OCSP)
   if(SSL_CONN_CONFIG(verifystatus))
-    SSL_set_tlsext_status_type(BACKEND->handle, TLSEXT_STATUSTYPE_ocsp);
+    SSL_set_tlsext_status_type(backend->handle, TLSEXT_STATUSTYPE_ocsp);
 #endif
 
 #if defined(OPENSSL_IS_BORINGSSL) && defined(ALLOW_RENEG)
-  SSL_set_renegotiate_mode(BACKEND->handle, ssl_renegotiate_freely);
+  SSL_set_renegotiate_mode(backend->handle, ssl_renegotiate_freely);
 #endif
 
-  SSL_set_connect_state(BACKEND->handle);
+  SSL_set_connect_state(backend->handle);
 
-  BACKEND->server_cert = 0x0;
+  backend->server_cert = 0x0;
 #ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
   if((0 == Curl_inet_pton(AF_INET, hostname, &addr)) &&
 #ifdef ENABLE_IPV6
      (0 == Curl_inet_pton(AF_INET6, hostname, &addr)) &&
 #endif
      sni &&
-     !SSL_set_tlsext_host_name(BACKEND->handle, hostname))
+     !SSL_set_tlsext_host_name(backend->handle, hostname))
     infof(data, "WARNING: failed to configure server name indication (SNI) "
           "TLS extension\n");
 #endif
@@ -2872,14 +2872,14 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     if(connectdata_idx >= 0 && sockindex_idx >= 0) {
       /* Store the data needed for the "new session" callback.
        * The sockindex is stored as a pointer to an array element. */
-      SSL_set_ex_data(BACKEND->handle, connectdata_idx, conn);
-      SSL_set_ex_data(BACKEND->handle, sockindex_idx, conn->sock + sockindex);
+      SSL_set_ex_data(backend->handle, connectdata_idx, conn);
+      SSL_set_ex_data(backend->handle, sockindex_idx, conn->sock + sockindex);
     }
 
     Curl_ssl_sessionid_lock(conn);
     if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL, sockindex)) {
       /* we got a session id, use it! */
-      if(!SSL_set_session(BACKEND->handle, ssl_sessionid)) {
+      if(!SSL_set_session(backend->handle, ssl_sessionid)) {
         Curl_ssl_sessionid_unlock(conn);
         failf(data, "SSL: SSL_set_session failed: %s",
               ossl_strerror(ERR_get_error(), error_buffer,
@@ -2899,9 +2899,9 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     DEBUGASSERT(handle != NULL);
     DEBUGASSERT(bio != NULL);
     BIO_set_ssl(bio, handle, FALSE);
-    SSL_set_bio(BACKEND->handle, bio, bio);
+    SSL_set_bio(backend->handle, bio, bio);
   }
-  else if(!SSL_set_fd(BACKEND->handle, (int)sockfd)) {
+  else if(!SSL_set_fd(backend->handle, (int)sockfd)) {
     /* pass the raw socket into the SSL layers */
     failf(data, "SSL: SSL_set_fd failed: %s",
           ossl_strerror(ERR_get_error(), error_buffer, sizeof(error_buffer)));
@@ -2920,24 +2920,25 @@ static CURLcode ossl_connect_step2(struct connectdata *conn, int sockindex)
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
   long * const certverifyresult = SSL_IS_PROXY() ?
     &data->set.proxy_ssl.certverifyresult : &data->set.ssl.certverifyresult;
+  struct ssl_backend_data *backend = connssl->backend;
   DEBUGASSERT(ssl_connect_2 == connssl->connecting_state
               || ssl_connect_2_reading == connssl->connecting_state
               || ssl_connect_2_writing == connssl->connecting_state);
 
   ERR_clear_error();
 
-  err = SSL_connect(BACKEND->handle);
+  err = SSL_connect(backend->handle);
   /* If keylogging is enabled but the keylog callback is not supported then log
      secrets here, immediately after SSL_connect by using tap_ssl_key. */
 #if defined(ENABLE_SSLKEYLOGFILE) && !defined(HAVE_KEYLOG_CALLBACK)
-  tap_ssl_key(BACKEND->handle, &BACKEND->tap_state);
+  tap_ssl_key(backend->handle, &backend->tap_state);
 #endif
 
   /* 1  is fine
      0  is "not successful but was shut down controlled"
      <0 is "handshake was not successful, because a fatal error occurred" */
   if(1 != err) {
-    int detail = SSL_get_error(BACKEND->handle, err);
+    int detail = SSL_get_error(backend->handle, err);
 
     if(SSL_ERROR_WANT_READ == detail) {
       connssl->connecting_state = ssl_connect_2_reading;
@@ -2977,7 +2978,7 @@ static CURLcode ossl_connect_step2(struct connectdata *conn, int sockindex)
          (reason == SSL_R_CERTIFICATE_VERIFY_FAILED)) {
         result = CURLE_PEER_FAILED_VERIFICATION;
 
-        lerr = SSL_get_verify_result(BACKEND->handle);
+        lerr = SSL_get_verify_result(backend->handle);
         if(lerr != X509_V_OK) {
           *certverifyresult = lerr;
           msnprintf(error_buffer, sizeof(error_buffer),
@@ -3026,8 +3027,8 @@ static CURLcode ossl_connect_step2(struct connectdata *conn, int sockindex)
 
     /* Informational message */
     infof(data, "SSL connection using %s / %s\n",
-          get_ssl_version_txt(BACKEND->handle),
-          SSL_get_cipher(BACKEND->handle));
+          get_ssl_version_txt(backend->handle),
+          SSL_get_cipher(backend->handle));
 
 #ifdef HAS_ALPN
     /* Sets data and len to negotiated protocol, len is 0 if no protocol was
@@ -3036,7 +3037,7 @@ static CURLcode ossl_connect_step2(struct connectdata *conn, int sockindex)
     if(conn->bits.tls_enable_alpn) {
       const unsigned char *neg_protocol;
       unsigned int len;
-      SSL_get0_alpn_selected(BACKEND->handle, &neg_protocol, &len);
+      SSL_get0_alpn_selected(backend->handle, &neg_protocol, &len);
       if(len != 0) {
         infof(data, "ALPN, server accepted to use %.*s\n", len, neg_protocol);
 
@@ -3171,8 +3172,9 @@ static CURLcode get_cert_chain(struct connectdata *conn,
   struct Curl_easy *data = conn->data;
   numcert_t numcerts;
   BIO *mem;
+  struct ssl_backend_data *backend = connssl->backend;
 
-  sk = SSL_get_peer_cert_chain(BACKEND->handle);
+  sk = SSL_get_peer_cert_chain(backend->handle);
   if(!sk) {
     return CURLE_OUT_OF_MEMORY;
   }
@@ -3458,13 +3460,14 @@ static CURLcode servercert(struct connectdata *conn,
   long * const certverifyresult = SSL_IS_PROXY() ?
     &data->set.proxy_ssl.certverifyresult : &data->set.ssl.certverifyresult;
   BIO *mem = BIO_new(BIO_s_mem());
+  struct ssl_backend_data *backend = connssl->backend;
 
   if(data->set.ssl.certinfo)
     /* we've been asked to gather certificate info! */
     (void)get_cert_chain(conn, connssl);
 
-  BACKEND->server_cert = SSL_get_peer_certificate(BACKEND->handle);
-  if(!BACKEND->server_cert) {
+  backend->server_cert = SSL_get_peer_certificate(backend->handle);
+  if(!backend->server_cert) {
     BIO_free(mem);
     if(!strict)
       return CURLE_OK;
@@ -3475,19 +3478,19 @@ static CURLcode servercert(struct connectdata *conn,
 
   infof(data, "%s certificate:\n", SSL_IS_PROXY() ? "Proxy" : "Server");
 
-  rc = x509_name_oneline(X509_get_subject_name(BACKEND->server_cert),
+  rc = x509_name_oneline(X509_get_subject_name(backend->server_cert),
                          buffer, sizeof(buffer));
   infof(data, " subject: %s\n", rc?"[NONE]":buffer);
 
 #ifndef CURL_DISABLE_VERBOSE_STRINGS
   {
     long len;
-    ASN1_TIME_print(mem, X509_get0_notBefore(BACKEND->server_cert));
+    ASN1_TIME_print(mem, X509_get0_notBefore(backend->server_cert));
     len = BIO_get_mem_data(mem, (char **) &ptr);
     infof(data, " start date: %.*s\n", len, ptr);
     (void)BIO_reset(mem);
 
-    ASN1_TIME_print(mem, X509_get0_notAfter(BACKEND->server_cert));
+    ASN1_TIME_print(mem, X509_get0_notAfter(backend->server_cert));
     len = BIO_get_mem_data(mem, (char **) &ptr);
     infof(data, " expire date: %.*s\n", len, ptr);
     (void)BIO_reset(mem);
@@ -3497,15 +3500,15 @@ static CURLcode servercert(struct connectdata *conn,
   BIO_free(mem);
 
   if(SSL_CONN_CONFIG(verifyhost)) {
-    result = verifyhost(conn, BACKEND->server_cert);
+    result = verifyhost(conn, backend->server_cert);
     if(result) {
-      X509_free(BACKEND->server_cert);
-      BACKEND->server_cert = NULL;
+      X509_free(backend->server_cert);
+      backend->server_cert = NULL;
       return result;
     }
   }
 
-  rc = x509_name_oneline(X509_get_issuer_name(BACKEND->server_cert),
+  rc = x509_name_oneline(X509_get_issuer_name(backend->server_cert),
                          buffer, sizeof(buffer));
   if(rc) {
     if(strict)
@@ -3527,8 +3530,8 @@ static CURLcode servercert(struct connectdata *conn,
               " error %s",
               ossl_strerror(ERR_get_error(), error_buffer,
                             sizeof(error_buffer)) );
-        X509_free(BACKEND->server_cert);
-        BACKEND->server_cert = NULL;
+        X509_free(backend->server_cert);
+        backend->server_cert = NULL;
         return CURLE_OUT_OF_MEMORY;
       }
 
@@ -3537,8 +3540,8 @@ static CURLcode servercert(struct connectdata *conn,
           failf(data, "SSL: Unable to open issuer cert (%s)",
                 SSL_SET_OPTION(issuercert));
         BIO_free(fp);
-        X509_free(BACKEND->server_cert);
-        BACKEND->server_cert = NULL;
+        X509_free(backend->server_cert);
+        backend->server_cert = NULL;
         return CURLE_SSL_ISSUER_ERROR;
       }
 
@@ -3549,19 +3552,19 @@ static CURLcode servercert(struct connectdata *conn,
                 SSL_SET_OPTION(issuercert));
         BIO_free(fp);
         X509_free(issuer);
-        X509_free(BACKEND->server_cert);
-        BACKEND->server_cert = NULL;
+        X509_free(backend->server_cert);
+        backend->server_cert = NULL;
         return CURLE_SSL_ISSUER_ERROR;
       }
 
-      if(X509_check_issued(issuer, BACKEND->server_cert) != X509_V_OK) {
+      if(X509_check_issued(issuer, backend->server_cert) != X509_V_OK) {
         if(strict)
           failf(data, "SSL: Certificate issuer check failed (%s)",
                 SSL_SET_OPTION(issuercert));
         BIO_free(fp);
         X509_free(issuer);
-        X509_free(BACKEND->server_cert);
-        BACKEND->server_cert = NULL;
+        X509_free(backend->server_cert);
+        backend->server_cert = NULL;
         return CURLE_SSL_ISSUER_ERROR;
       }
 
@@ -3571,7 +3574,7 @@ static CURLcode servercert(struct connectdata *conn,
       X509_free(issuer);
     }
 
-    lerr = *certverifyresult = SSL_get_verify_result(BACKEND->handle);
+    lerr = *certverifyresult = SSL_get_verify_result(backend->handle);
 
     if(*certverifyresult != X509_V_OK) {
       if(SSL_CONN_CONFIG(verifypeer)) {
@@ -3596,8 +3599,8 @@ static CURLcode servercert(struct connectdata *conn,
   if(SSL_CONN_CONFIG(verifystatus)) {
     result = verifystatus(conn, connssl);
     if(result) {
-      X509_free(BACKEND->server_cert);
-      BACKEND->server_cert = NULL;
+      X509_free(backend->server_cert);
+      backend->server_cert = NULL;
       return result;
     }
   }
@@ -3610,13 +3613,13 @@ static CURLcode servercert(struct connectdata *conn,
   ptr = SSL_IS_PROXY() ? data->set.str[STRING_SSL_PINNEDPUBLICKEY_PROXY] :
                          data->set.str[STRING_SSL_PINNEDPUBLICKEY_ORIG];
   if(!result && ptr) {
-    result = pkp_pin_peer_pubkey(data, BACKEND->server_cert, ptr);
+    result = pkp_pin_peer_pubkey(data, backend->server_cert, ptr);
     if(result)
       failf(data, "SSL: public key does not match pinned public key!");
   }
 
-  X509_free(BACKEND->server_cert);
-  BACKEND->server_cert = NULL;
+  X509_free(backend->server_cert);
+  backend->server_cert = NULL;
   connssl->connecting_state = ssl_connect_done;
 
   return result;
@@ -3810,14 +3813,15 @@ static ssize_t ossl_send(struct connectdata *conn,
   int memlen;
   int rc;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
 
   ERR_clear_error();
 
   memlen = (len > (size_t)INT_MAX) ? INT_MAX : (int)len;
-  rc = SSL_write(BACKEND->handle, mem, memlen);
+  rc = SSL_write(backend->handle, mem, memlen);
 
   if(rc <= 0) {
-    err = SSL_get_error(BACKEND->handle, rc);
+    err = SSL_get_error(backend->handle, rc);
 
     switch(err) {
     case SSL_ERROR_WANT_READ:
@@ -3884,14 +3888,15 @@ static ssize_t ossl_recv(struct connectdata *conn, /* connection data */
   ssize_t nread;
   int buffsize;
   struct ssl_connect_data *connssl = &conn->ssl[num];
+  struct ssl_backend_data *backend = connssl->backend;
 
   ERR_clear_error();
 
   buffsize = (buffersize > (size_t)INT_MAX) ? INT_MAX : (int)buffersize;
-  nread = (ssize_t)SSL_read(BACKEND->handle, buf, buffsize);
+  nread = (ssize_t)SSL_read(backend->handle, buf, buffsize);
   if(nread <= 0) {
     /* failed SSL_read */
-    int err = SSL_get_error(BACKEND->handle, (int)nread);
+    int err = SSL_get_error(backend->handle, (int)nread);
 
     switch(err) {
     case SSL_ERROR_NONE: /* this is not an error */
@@ -4097,8 +4102,9 @@ static void *Curl_ossl_get_internals(struct ssl_connect_data *connssl,
                                      CURLINFO info)
 {
   /* Legacy: CURLINFO_TLS_SESSION must return an SSL_CTX pointer. */
+  struct ssl_backend_data *backend = connssl->backend;
   return info == CURLINFO_TLS_SESSION ?
-         (void *)BACKEND->ctx : (void *)BACKEND->handle;
+         (void *)backend->ctx : (void *)backend->handle;
 }
 
 const struct Curl_ssl Curl_ssl_openssl = {