intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 1112 insertions, 0 deletions

diff --git a/contrib/libs/curl/lib/vtls/mbedtls.c b/contrib/libs/curl/lib/vtls/mbedtls.c
new file mode 100644
index 0000000000..e30f660fbb
--- /dev/null
+++ b/contrib/libs/curl/lib/vtls/mbedtls.c
@@ -0,0 +1,1112 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2010 - 2011, Hoi-Ho Chan, <hoiho.chan@gmail.com>
+ * Copyright (C) 2012 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/*
+ * Source file for all mbedTLS-specific code for the TLS/SSL layer. No code
+ * but vtls.c should ever call or use these functions.
+ *
+ */
+
+#include "curl_setup.h"
+
+#ifdef USE_MBEDTLS
+
+/* Define this to enable lots of debugging for mbedTLS */
+/* #define MBEDTLS_DEBUG */
+
+#error #include <mbedtls/version.h>
+#if MBEDTLS_VERSION_NUMBER >= 0x02040000
+#error #include <mbedtls/net_sockets.h>
+#else
+#error #include <mbedtls/net.h>
+#endif
+#error #include <mbedtls/ssl.h>
+#error #include <mbedtls/certs.h>
+#error #include <mbedtls/x509.h>
+
+#error #include <mbedtls/error.h>
+#error #include <mbedtls/entropy.h>
+#error #include <mbedtls/ctr_drbg.h>
+#error #include <mbedtls/sha256.h>
+
+#if MBEDTLS_VERSION_MAJOR >= 2
+#  ifdef MBEDTLS_DEBUG
+#    error #include <mbedtls/debug.h>
+#  endif
+#endif
+
+#include "urldata.h"
+#include "sendf.h"
+#include "inet_pton.h"
+#include "mbedtls.h"
+#include "vtls.h"
+#include "parsedate.h"
+#include "connect.h" /* for the connect timeout */
+#include "select.h"
+#include "multiif.h"
+#error #include "mbedtls_threadlock.h"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+struct ssl_backend_data {
+  mbedtls_ctr_drbg_context ctr_drbg;
+  mbedtls_entropy_context entropy;
+  mbedtls_ssl_context ssl;
+  int server_fd;
+  mbedtls_x509_crt cacert;
+  mbedtls_x509_crt clicert;
+  mbedtls_x509_crl crl;
+  mbedtls_pk_context pk;
+  mbedtls_ssl_config config;
+  const char *protocols[3];
+};
+
+/* apply threading? */
+#if defined(USE_THREADS_POSIX) || defined(USE_THREADS_WIN32)
+#define THREADING_SUPPORT
+#endif
+
+#if defined(THREADING_SUPPORT)
+static mbedtls_entropy_context ts_entropy;
+
+static int entropy_init_initialized = 0;
+
+/* start of entropy_init_mutex() */
+static void entropy_init_mutex(mbedtls_entropy_context *ctx)
+{
+  /* lock 0 = entropy_init_mutex() */
+  Curl_mbedtlsthreadlock_lock_function(0);
+  if(entropy_init_initialized == 0) {
+    mbedtls_entropy_init(ctx);
+    entropy_init_initialized = 1;
+  }
+  Curl_mbedtlsthreadlock_unlock_function(0);
+}
+/* end of entropy_init_mutex() */
+
+/* start of entropy_func_mutex() */
+static int entropy_func_mutex(void *data, unsigned char *output, size_t len)
+{
+  int ret;
+  /* lock 1 = entropy_func_mutex() */
+  Curl_mbedtlsthreadlock_lock_function(1);
+  ret = mbedtls_entropy_func(data, output, len);
+  Curl_mbedtlsthreadlock_unlock_function(1);
+
+  return ret;
+}
+/* end of entropy_func_mutex() */
+
+#endif /* THREADING_SUPPORT */
+
+#ifdef MBEDTLS_DEBUG
+static void mbed_debug(void *context, int level, const char *f_name,
+                       int line_nb, const char *line)
+{
+  struct Curl_easy *data = NULL;
+
+  if(!context)
+    return;
+
+  data = (struct Curl_easy *)context;
+
+  infof(data, "%s", line);
+  (void) level;
+}
+#else
+#endif
+
+/* ALPN for http2? */
+#ifdef USE_NGHTTP2
+#  undef HAS_ALPN
+#  ifdef MBEDTLS_SSL_ALPN
+#    define HAS_ALPN
+#  endif
+#endif
+
+
+/*
+ *  profile
+ */
+static const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_fr =
+{
+  /* Hashes from SHA-1 and above */
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_SHA1) |
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_RIPEMD160) |
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_SHA224) |
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_SHA256) |
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_SHA384) |
+  MBEDTLS_X509_ID_FLAG(MBEDTLS_MD_SHA512),
+  0xFFFFFFF, /* Any PK alg    */
+  0xFFFFFFF, /* Any curve     */
+  1024,      /* RSA min key len */
+};
+
+/* See https://tls.mbed.org/discussions/generic/
+   howto-determine-exact-buffer-len-for-mbedtls_pk_write_pubkey_der
+*/
+#define RSA_PUB_DER_MAX_BYTES   (38 + 2 * MBEDTLS_MPI_MAX_SIZE)
+#define ECP_PUB_DER_MAX_BYTES   (30 + 2 * MBEDTLS_ECP_MAX_BYTES)
+
+#define PUB_DER_MAX_BYTES   (RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \
+                             RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES)
+
+static Curl_recv mbed_recv;
+static Curl_send mbed_send;
+
+static CURLcode mbedtls_version_from_curl(int *mbedver, long version)
+{
+  switch(version) {
+    case CURL_SSLVERSION_TLSv1_0:
+      *mbedver = MBEDTLS_SSL_MINOR_VERSION_1;
+      return CURLE_OK;
+    case CURL_SSLVERSION_TLSv1_1:
+      *mbedver = MBEDTLS_SSL_MINOR_VERSION_2;
+      return CURLE_OK;
+    case CURL_SSLVERSION_TLSv1_2:
+      *mbedver = MBEDTLS_SSL_MINOR_VERSION_3;
+      return CURLE_OK;
+    case CURL_SSLVERSION_TLSv1_3:
+      break;
+  }
+  return CURLE_SSL_CONNECT_ERROR;
+}
+
+static CURLcode
+set_ssl_version_min_max(struct connectdata *conn, int sockindex)
+{
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  int mbedtls_ver_min = MBEDTLS_SSL_MINOR_VERSION_1;
+  int mbedtls_ver_max = MBEDTLS_SSL_MINOR_VERSION_1;
+  long ssl_version = SSL_CONN_CONFIG(version);
+  long ssl_version_max = SSL_CONN_CONFIG(version_max);
+  CURLcode result = CURLE_OK;
+
+  switch(ssl_version) {
+    case CURL_SSLVERSION_DEFAULT:
+    case CURL_SSLVERSION_TLSv1:
+      ssl_version = CURL_SSLVERSION_TLSv1_0;
+      break;
+  }
+
+  switch(ssl_version_max) {
+    case CURL_SSLVERSION_MAX_NONE:
+    case CURL_SSLVERSION_MAX_DEFAULT:
+      ssl_version_max = CURL_SSLVERSION_MAX_TLSv1_2;
+      break;
+  }
+
+  result = mbedtls_version_from_curl(&mbedtls_ver_min, ssl_version);
+  if(result) {
+    failf(data, "unsupported min version passed via CURLOPT_SSLVERSION");
+    return result;
+  }
+  result = mbedtls_version_from_curl(&mbedtls_ver_max, ssl_version_max >> 16);
+  if(result) {
+    failf(data, "unsupported max version passed via CURLOPT_SSLVERSION");
+    return result;
+  }
+
+  mbedtls_ssl_conf_min_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
+                               mbedtls_ver_min);
+  mbedtls_ssl_conf_max_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
+                               mbedtls_ver_max);
+
+  return result;
+}
+
+static CURLcode
+mbed_connect_step1(struct connectdata *conn,
+                   int sockindex)
+{
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  const char * const ssl_cafile = SSL_CONN_CONFIG(CAfile);
+  const bool verifypeer = SSL_CONN_CONFIG(verifypeer);
+  const char * const ssl_capath = SSL_CONN_CONFIG(CApath);
+  char * const ssl_cert = SSL_SET_OPTION(primary.clientcert);
+  const char * const ssl_crlfile = SSL_SET_OPTION(CRLfile);
+#ifndef CURL_DISABLE_PROXY
+  const char * const hostname = SSL_IS_PROXY() ? conn->http_proxy.host.name :
+    conn->host.name;
+  const long int port = SSL_IS_PROXY() ? conn->port : conn->remote_port;
+#else
+  const char * const hostname = conn->host.name;
+  const long int port = conn->remote_port;
+#endif
+  int ret = -1;
+  char errorbuf[128];
+  errorbuf[0] = 0;
+
+  /* mbedTLS only supports SSLv3 and TLSv1 */
+  if(SSL_CONN_CONFIG(version) == CURL_SSLVERSION_SSLv2) {
+    failf(data, "mbedTLS does not support SSLv2");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+#ifdef THREADING_SUPPORT
+  entropy_init_mutex(&ts_entropy);
+  mbedtls_ctr_drbg_init(&backend->ctr_drbg);
+
+  ret = mbedtls_ctr_drbg_seed(&backend->ctr_drbg, entropy_func_mutex,
+                              &ts_entropy, NULL, 0);
+  if(ret) {
+#ifdef MBEDTLS_ERROR_C
+    mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+    failf(data, "Failed - mbedTLS: ctr_drbg_init returned (-0x%04X) %s\n",
+          -ret, errorbuf);
+  }
+#else
+  mbedtls_entropy_init(&backend->entropy);
+  mbedtls_ctr_drbg_init(&backend->ctr_drbg);
+
+  ret = mbedtls_ctr_drbg_seed(&backend->ctr_drbg, mbedtls_entropy_func,
+                              &backend->entropy, NULL, 0);
+  if(ret) {
+#ifdef MBEDTLS_ERROR_C
+    mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+    failf(data, "Failed - mbedTLS: ctr_drbg_init returned (-0x%04X) %s\n",
+          -ret, errorbuf);
+  }
+#endif /* THREADING_SUPPORT */
+
+  /* Load the trusted CA */
+  mbedtls_x509_crt_init(&backend->cacert);
+
+  if(ssl_cafile) {
+    ret = mbedtls_x509_crt_parse_file(&backend->cacert, ssl_cafile);
+
+    if(ret<0) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "Error reading ca cert file %s - mbedTLS: (-0x%04X) %s",
+            ssl_cafile, -ret, errorbuf);
+
+      if(verifypeer)
+        return CURLE_SSL_CACERT_BADFILE;
+    }
+  }
+
+  if(ssl_capath) {
+    ret = mbedtls_x509_crt_parse_path(&backend->cacert, ssl_capath);
+
+    if(ret<0) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "Error reading ca cert path %s - mbedTLS: (-0x%04X) %s",
+            ssl_capath, -ret, errorbuf);
+
+      if(verifypeer)
+        return CURLE_SSL_CACERT_BADFILE;
+    }
+  }
+
+  /* Load the client certificate */
+  mbedtls_x509_crt_init(&backend->clicert);
+
+  if(ssl_cert) {
+    ret = mbedtls_x509_crt_parse_file(&backend->clicert, ssl_cert);
+
+    if(ret) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "Error reading client cert file %s - mbedTLS: (-0x%04X) %s",
+            ssl_cert, -ret, errorbuf);
+
+      return CURLE_SSL_CERTPROBLEM;
+    }
+  }
+
+  /* Load the client private key */
+  mbedtls_pk_init(&backend->pk);
+
+  if(SSL_SET_OPTION(key)) {
+    ret = mbedtls_pk_parse_keyfile(&backend->pk, SSL_SET_OPTION(key),
+                                   SSL_SET_OPTION(key_passwd));
+    if(ret == 0 && !(mbedtls_pk_can_do(&backend->pk, MBEDTLS_PK_RSA) ||
+                     mbedtls_pk_can_do(&backend->pk, MBEDTLS_PK_ECKEY)))
+      ret = MBEDTLS_ERR_PK_TYPE_MISMATCH;
+
+    if(ret) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "Error reading private key %s - mbedTLS: (-0x%04X) %s",
+            SSL_SET_OPTION(key), -ret, errorbuf);
+
+      return CURLE_SSL_CERTPROBLEM;
+    }
+  }
+
+  /* Load the CRL */
+  mbedtls_x509_crl_init(&backend->crl);
+
+  if(ssl_crlfile) {
+    ret = mbedtls_x509_crl_parse_file(&backend->crl, ssl_crlfile);
+
+    if(ret) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "Error reading CRL file %s - mbedTLS: (-0x%04X) %s",
+            ssl_crlfile, -ret, errorbuf);
+
+      return CURLE_SSL_CRL_BADFILE;
+    }
+  }
+
+  infof(data, "mbedTLS: Connecting to %s:%ld\n", hostname, port);
+
+  mbedtls_ssl_config_init(&backend->config);
+
+  mbedtls_ssl_init(&backend->ssl);
+  if(mbedtls_ssl_setup(&backend->ssl, &backend->config)) {
+    failf(data, "mbedTLS: ssl_init failed");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+  ret = mbedtls_ssl_config_defaults(&backend->config,
+                                    MBEDTLS_SSL_IS_CLIENT,
+                                    MBEDTLS_SSL_TRANSPORT_STREAM,
+                                    MBEDTLS_SSL_PRESET_DEFAULT);
+  if(ret) {
+    failf(data, "mbedTLS: ssl_config failed");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  /* new profile with RSA min key len = 1024 ... */
+  mbedtls_ssl_conf_cert_profile(&backend->config,
+                                &mbedtls_x509_crt_profile_fr);
+
+  switch(SSL_CONN_CONFIG(version)) {
+  case CURL_SSLVERSION_DEFAULT:
+  case CURL_SSLVERSION_TLSv1:
+    mbedtls_ssl_conf_min_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
+                                 MBEDTLS_SSL_MINOR_VERSION_1);
+    infof(data, "mbedTLS: Set min SSL version to TLS 1.0\n");
+    break;
+  case CURL_SSLVERSION_SSLv3:
+    mbedtls_ssl_conf_min_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
+                                 MBEDTLS_SSL_MINOR_VERSION_0);
+    mbedtls_ssl_conf_max_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
+                                 MBEDTLS_SSL_MINOR_VERSION_0);
+    infof(data, "mbedTLS: Set SSL version to SSLv3\n");
+    break;
+  case CURL_SSLVERSION_TLSv1_0:
+  case CURL_SSLVERSION_TLSv1_1:
+  case CURL_SSLVERSION_TLSv1_2:
+  case CURL_SSLVERSION_TLSv1_3:
+    {
+      CURLcode result = set_ssl_version_min_max(conn, sockindex);
+      if(result != CURLE_OK)
+        return result;
+      break;
+    }
+  default:
+    failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  mbedtls_ssl_conf_authmode(&backend->config, MBEDTLS_SSL_VERIFY_OPTIONAL);
+
+  mbedtls_ssl_conf_rng(&backend->config, mbedtls_ctr_drbg_random,
+                       &backend->ctr_drbg);
+  mbedtls_ssl_set_bio(&backend->ssl, &conn->sock[sockindex],
+                      mbedtls_net_send,
+                      mbedtls_net_recv,
+                      NULL /*  rev_timeout() */);
+
+  mbedtls_ssl_conf_ciphersuites(&backend->config,
+                                mbedtls_ssl_list_ciphersuites());
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+  mbedtls_ssl_conf_renegotiation(&backend->config,
+                                 MBEDTLS_SSL_RENEGOTIATION_ENABLED);
+#endif
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+  mbedtls_ssl_conf_session_tickets(&backend->config,
+                                   MBEDTLS_SSL_SESSION_TICKETS_DISABLED);
+#endif
+
+  /* Check if there's a cached ID we can/should use here! */
+  if(SSL_SET_OPTION(primary.sessionid)) {
+    void *old_session = NULL;
+
+    Curl_ssl_sessionid_lock(conn);
+    if(!Curl_ssl_getsessionid(conn, &old_session, NULL, sockindex)) {
+      ret = mbedtls_ssl_set_session(&backend->ssl, old_session);
+      if(ret) {
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "mbedtls_ssl_set_session returned -0x%x", -ret);
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      infof(data, "mbedTLS re-using session\n");
+    }
+    Curl_ssl_sessionid_unlock(conn);
+  }
+
+  mbedtls_ssl_conf_ca_chain(&backend->config,
+                            &backend->cacert,
+                            &backend->crl);
+
+  if(SSL_SET_OPTION(key)) {
+    mbedtls_ssl_conf_own_cert(&backend->config,
+                              &backend->clicert, &backend->pk);
+  }
+  if(mbedtls_ssl_set_hostname(&backend->ssl, hostname)) {
+    /* mbedtls_ssl_set_hostname() sets the name to use in CN/SAN checks *and*
+       the name to set in the SNI extension. So even if curl connects to a
+       host specified as an IP address, this function must be used. */
+    failf(data, "couldn't set hostname in mbedTLS");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+#ifdef HAS_ALPN
+  if(conn->bits.tls_enable_alpn) {
+    const char **p = &backend->protocols[0];
+#ifdef USE_NGHTTP2
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2)
+      *p++ = NGHTTP2_PROTO_VERSION_ID;
+#endif
+    *p++ = ALPN_HTTP_1_1;
+    *p = NULL;
+    /* this function doesn't clone the protocols array, which is why we need
+       to keep it around */
+    if(mbedtls_ssl_conf_alpn_protocols(&backend->config,
+                                       &backend->protocols[0])) {
+      failf(data, "Failed setting ALPN protocols");
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+    for(p = &backend->protocols[0]; *p; ++p)
+      infof(data, "ALPN, offering %s\n", *p);
+  }
+#endif
+
+#ifdef MBEDTLS_DEBUG
+  /* In order to make that work in mbedtls MBEDTLS_DEBUG_C must be defined. */
+  mbedtls_ssl_conf_dbg(&backend->config, mbed_debug, data);
+  /* - 0 No debug
+   * - 1 Error
+   * - 2 State change
+   * - 3 Informational
+   * - 4 Verbose
+   */
+  mbedtls_debug_set_threshold(4);
+#endif
+
+  /* give application a chance to interfere with mbedTLS set up. */
+  if(data->set.ssl.fsslctx) {
+    ret = (*data->set.ssl.fsslctx)(data, &backend->config,
+                                   data->set.ssl.fsslctxp);
+    if(ret) {
+      failf(data, "error signaled by ssl ctx callback");
+      return ret;
+    }
+  }
+
+  connssl->connecting_state = ssl_connect_2;
+
+  return CURLE_OK;
+}
+
+static CURLcode
+mbed_connect_step2(struct connectdata *conn,
+                   int sockindex)
+{
+  int ret;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  const mbedtls_x509_crt *peercert;
+#ifndef CURL_DISABLE_PROXY
+  const char * const pinnedpubkey = SSL_IS_PROXY() ?
+    data->set.str[STRING_SSL_PINNEDPUBLICKEY_PROXY] :
+    data->set.str[STRING_SSL_PINNEDPUBLICKEY_ORIG];
+#else
+  const char * const pinnedpubkey =
+    data->set.str[STRING_SSL_PINNEDPUBLICKEY_ORIG];
+#endif
+
+  conn->recv[sockindex] = mbed_recv;
+  conn->send[sockindex] = mbed_send;
+
+  ret = mbedtls_ssl_handshake(&backend->ssl);
+
+  if(ret == MBEDTLS_ERR_SSL_WANT_READ) {
+    connssl->connecting_state = ssl_connect_2_reading;
+    return CURLE_OK;
+  }
+  else if(ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
+    connssl->connecting_state = ssl_connect_2_writing;
+    return CURLE_OK;
+  }
+  else if(ret) {
+    char errorbuf[128];
+    errorbuf[0] = 0;
+#ifdef MBEDTLS_ERROR_C
+    mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+    failf(data, "ssl_handshake returned - mbedTLS: (-0x%04X) %s",
+          -ret, errorbuf);
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  infof(data, "mbedTLS: Handshake complete, cipher is %s\n",
+        mbedtls_ssl_get_ciphersuite(&backend->ssl)
+    );
+
+  ret = mbedtls_ssl_get_verify_result(&backend->ssl);
+
+  if(!SSL_CONN_CONFIG(verifyhost))
+    /* Ignore hostname errors if verifyhost is disabled */
+    ret &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
+
+  if(ret && SSL_CONN_CONFIG(verifypeer)) {
+    if(ret & MBEDTLS_X509_BADCERT_EXPIRED)
+      failf(data, "Cert verify failed: BADCERT_EXPIRED");
+
+    else if(ret & MBEDTLS_X509_BADCERT_REVOKED)
+      failf(data, "Cert verify failed: BADCERT_REVOKED");
+
+    else if(ret & MBEDTLS_X509_BADCERT_CN_MISMATCH)
+      failf(data, "Cert verify failed: BADCERT_CN_MISMATCH");
+
+    else if(ret & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
+      failf(data, "Cert verify failed: BADCERT_NOT_TRUSTED");
+
+    else if(ret & MBEDTLS_X509_BADCERT_FUTURE)
+      failf(data, "Cert verify failed: BADCERT_FUTURE");
+
+    return CURLE_PEER_FAILED_VERIFICATION;
+  }
+
+  peercert = mbedtls_ssl_get_peer_cert(&backend->ssl);
+
+  if(peercert && data->set.verbose) {
+    const size_t bufsize = 16384;
+    char *buffer = malloc(bufsize);
+
+    if(!buffer)
+      return CURLE_OUT_OF_MEMORY;
+
+    if(mbedtls_x509_crt_info(buffer, bufsize, "* ", peercert) > 0)
+      infof(data, "Dumping cert info:\n%s\n", buffer);
+    else
+      infof(data, "Unable to dump certificate information.\n");
+
+    free(buffer);
+  }
+
+  if(pinnedpubkey) {
+    int size;
+    CURLcode result;
+    mbedtls_x509_crt *p;
+    unsigned char pubkey[PUB_DER_MAX_BYTES];
+
+    if(!peercert || !peercert->raw.p || !peercert->raw.len) {
+      failf(data, "Failed due to missing peer certificate");
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    p = calloc(1, sizeof(*p));
+
+    if(!p)
+      return CURLE_OUT_OF_MEMORY;
+
+    mbedtls_x509_crt_init(p);
+
+    /* Make a copy of our const peercert because mbedtls_pk_write_pubkey_der
+       needs a non-const key, for now.
+       https://github.com/ARMmbed/mbedtls/issues/396 */
+    if(mbedtls_x509_crt_parse_der(p, peercert->raw.p, peercert->raw.len)) {
+      failf(data, "Failed copying peer certificate");
+      mbedtls_x509_crt_free(p);
+      free(p);
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    size = mbedtls_pk_write_pubkey_der(&p->pk, pubkey, PUB_DER_MAX_BYTES);
+
+    if(size <= 0) {
+      failf(data, "Failed copying public key from peer certificate");
+      mbedtls_x509_crt_free(p);
+      free(p);
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    /* mbedtls_pk_write_pubkey_der writes data at the end of the buffer. */
+    result = Curl_pin_peer_pubkey(data,
+                                  pinnedpubkey,
+                                  &pubkey[PUB_DER_MAX_BYTES - size], size);
+    if(result) {
+      mbedtls_x509_crt_free(p);
+      free(p);
+      return result;
+    }
+
+    mbedtls_x509_crt_free(p);
+    free(p);
+  }
+
+#ifdef HAS_ALPN
+  if(conn->bits.tls_enable_alpn) {
+    const char *next_protocol = mbedtls_ssl_get_alpn_protocol(&backend->ssl);
+
+    if(next_protocol) {
+      infof(data, "ALPN, server accepted to use %s\n", next_protocol);
+#ifdef USE_NGHTTP2
+      if(!strncmp(next_protocol, NGHTTP2_PROTO_VERSION_ID,
+                  NGHTTP2_PROTO_VERSION_ID_LEN) &&
+         !next_protocol[NGHTTP2_PROTO_VERSION_ID_LEN]) {
+        conn->negnpn = CURL_HTTP_VERSION_2;
+      }
+      else
+#endif
+        if(!strncmp(next_protocol, ALPN_HTTP_1_1, ALPN_HTTP_1_1_LENGTH) &&
+           !next_protocol[ALPN_HTTP_1_1_LENGTH]) {
+          conn->negnpn = CURL_HTTP_VERSION_1_1;
+        }
+    }
+    else {
+      infof(data, "ALPN, server did not agree to a protocol\n");
+    }
+    Curl_multiuse_state(conn, conn->negnpn == CURL_HTTP_VERSION_2 ?
+                        BUNDLE_MULTIPLEX : BUNDLE_NO_MULTIUSE);
+  }
+#endif
+
+  connssl->connecting_state = ssl_connect_3;
+  infof(data, "SSL connected\n");
+
+  return CURLE_OK;
+}
+
+static CURLcode
+mbed_connect_step3(struct connectdata *conn,
+                   int sockindex)
+{
+  CURLcode retcode = CURLE_OK;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  struct Curl_easy *data = conn->data;
+
+  DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
+
+  if(SSL_SET_OPTION(primary.sessionid)) {
+    int ret;
+    mbedtls_ssl_session *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
+
+    our_ssl_sessionid = malloc(sizeof(mbedtls_ssl_session));
+    if(!our_ssl_sessionid)
+      return CURLE_OUT_OF_MEMORY;
+
+    mbedtls_ssl_session_init(our_ssl_sessionid);
+
+    ret = mbedtls_ssl_get_session(&backend->ssl, our_ssl_sessionid);
+    if(ret) {
+      if(ret != MBEDTLS_ERR_SSL_ALLOC_FAILED)
+        mbedtls_ssl_session_free(our_ssl_sessionid);
+      free(our_ssl_sessionid);
+      failf(data, "mbedtls_ssl_get_session returned -0x%x", -ret);
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+
+    /* If there's already a matching session in the cache, delete it */
+    Curl_ssl_sessionid_lock(conn);
+    if(!Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL, sockindex))
+      Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+
+    retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid, 0, sockindex);
+    Curl_ssl_sessionid_unlock(conn);
+    if(retcode) {
+      mbedtls_ssl_session_free(our_ssl_sessionid);
+      free(our_ssl_sessionid);
+      failf(data, "failed to store ssl session");
+      return retcode;
+    }
+  }
+
+  connssl->connecting_state = ssl_connect_done;
+
+  return CURLE_OK;
+}
+
+static ssize_t mbed_send(struct connectdata *conn, int sockindex,
+                         const void *mem, size_t len,
+                         CURLcode *curlcode)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  int ret = -1;
+
+  ret = mbedtls_ssl_write(&backend->ssl,
+                          (unsigned char *)mem, len);
+
+  if(ret < 0) {
+    *curlcode = (ret == MBEDTLS_ERR_SSL_WANT_WRITE) ?
+      CURLE_AGAIN : CURLE_SEND_ERROR;
+    ret = -1;
+  }
+
+  return ret;
+}
+
+static void Curl_mbedtls_close_all(struct Curl_easy *data)
+{
+  (void)data;
+}
+
+static void Curl_mbedtls_close(struct connectdata *conn, int sockindex)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  mbedtls_pk_free(&backend->pk);
+  mbedtls_x509_crt_free(&backend->clicert);
+  mbedtls_x509_crt_free(&backend->cacert);
+  mbedtls_x509_crl_free(&backend->crl);
+  mbedtls_ssl_config_free(&backend->config);
+  mbedtls_ssl_free(&backend->ssl);
+  mbedtls_ctr_drbg_free(&backend->ctr_drbg);
+#ifndef THREADING_SUPPORT
+  mbedtls_entropy_free(&backend->entropy);
+#endif /* THREADING_SUPPORT */
+}
+
+static ssize_t mbed_recv(struct connectdata *conn, int num,
+                         char *buf, size_t buffersize,
+                         CURLcode *curlcode)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[num];
+  struct ssl_backend_data *backend = connssl->backend;
+  int ret = -1;
+  ssize_t len = -1;
+
+  memset(buf, 0, buffersize);
+  ret = mbedtls_ssl_read(&backend->ssl, (unsigned char *)buf,
+                         buffersize);
+
+  if(ret <= 0) {
+    if(ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
+      return 0;
+
+    *curlcode = (ret == MBEDTLS_ERR_SSL_WANT_READ) ?
+      CURLE_AGAIN : CURLE_RECV_ERROR;
+    return -1;
+  }
+
+  len = ret;
+
+  return len;
+}
+
+static void Curl_mbedtls_session_free(void *ptr)
+{
+  mbedtls_ssl_session_free(ptr);
+  free(ptr);
+}
+
+static size_t Curl_mbedtls_version(char *buffer, size_t size)
+{
+#ifdef MBEDTLS_VERSION_C
+  /* if mbedtls_version_get_number() is available it is better */
+  unsigned int version = mbedtls_version_get_number();
+  return msnprintf(buffer, size, "mbedTLS/%u.%u.%u", version>>24,
+                   (version>>16)&0xff, (version>>8)&0xff);
+#else
+  return msnprintf(buffer, size, "mbedTLS/%s", MBEDTLS_VERSION_STRING);
+#endif
+}
+
+static CURLcode Curl_mbedtls_random(struct Curl_easy *data,
+                                    unsigned char *entropy, size_t length)
+{
+#if defined(MBEDTLS_CTR_DRBG_C)
+  int ret = -1;
+  char errorbuf[128];
+  mbedtls_entropy_context ctr_entropy;
+  mbedtls_ctr_drbg_context ctr_drbg;
+  mbedtls_entropy_init(&ctr_entropy);
+  mbedtls_ctr_drbg_init(&ctr_drbg);
+  errorbuf[0] = 0;
+
+  ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
+                              &ctr_entropy, NULL, 0);
+
+  if(ret) {
+#ifdef MBEDTLS_ERROR_C
+    mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+    failf(data, "Failed - mbedTLS: ctr_drbg_seed returned (-0x%04X) %s\n",
+          -ret, errorbuf);
+  }
+  else {
+    ret = mbedtls_ctr_drbg_random(&ctr_drbg, entropy, length);
+
+    if(ret) {
+#ifdef MBEDTLS_ERROR_C
+      mbedtls_strerror(ret, errorbuf, sizeof(errorbuf));
+#endif /* MBEDTLS_ERROR_C */
+      failf(data, "mbedTLS: ctr_drbg_init returned (-0x%04X) %s\n",
+            -ret, errorbuf);
+    }
+  }
+
+  mbedtls_ctr_drbg_free(&ctr_drbg);
+  mbedtls_entropy_free(&ctr_entropy);
+
+  return ret == 0 ? CURLE_OK : CURLE_FAILED_INIT;
+#elif defined(MBEDTLS_HAVEGE_C)
+  mbedtls_havege_state hs;
+  mbedtls_havege_init(&hs);
+  mbedtls_havege_random(&hs, entropy, length);
+  mbedtls_havege_free(&hs);
+  return CURLE_OK;
+#else
+  return CURLE_NOT_BUILT_IN;
+#endif
+}
+
+static CURLcode
+mbed_connect_common(struct connectdata *conn,
+                    int sockindex,
+                    bool nonblocking,
+                    bool *done)
+{
+  CURLcode retcode;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  curl_socket_t sockfd = conn->sock[sockindex];
+  timediff_t timeout_ms;
+  int what;
+
+  /* check if the connection has already been established */
+  if(ssl_connection_complete == connssl->state) {
+    *done = TRUE;
+    return CURLE_OK;
+  }
+
+  if(ssl_connect_1 == connssl->connecting_state) {
+    /* Find out how much more time we're allowed */
+    timeout_ms = Curl_timeleft(data, NULL, TRUE);
+
+    if(timeout_ms < 0) {
+      /* no need to continue if time already is up */
+      failf(data, "SSL connection timeout");
+      return CURLE_OPERATION_TIMEDOUT;
+    }
+    retcode = mbed_connect_step1(conn, sockindex);
+    if(retcode)
+      return retcode;
+  }
+
+  while(ssl_connect_2 == connssl->connecting_state ||
+        ssl_connect_2_reading == connssl->connecting_state ||
+        ssl_connect_2_writing == connssl->connecting_state) {
+
+    /* check allowed time left */
+    timeout_ms = Curl_timeleft(data, NULL, TRUE);
+
+    if(timeout_ms < 0) {
+      /* no need to continue if time already is up */
+      failf(data, "SSL connection timeout");
+      return CURLE_OPERATION_TIMEDOUT;
+    }
+
+    /* if ssl is expecting something, check if it's available. */
+    if(connssl->connecting_state == ssl_connect_2_reading
+       || connssl->connecting_state == ssl_connect_2_writing) {
+
+      curl_socket_t writefd = ssl_connect_2_writing ==
+        connssl->connecting_state?sockfd:CURL_SOCKET_BAD;
+      curl_socket_t readfd = ssl_connect_2_reading ==
+        connssl->connecting_state?sockfd:CURL_SOCKET_BAD;
+
+      what = Curl_socket_check(readfd, CURL_SOCKET_BAD, writefd,
+                               nonblocking ? 0 : timeout_ms);
+      if(what < 0) {
+        /* fatal error */
+        failf(data, "select/poll on SSL socket, errno: %d", SOCKERRNO);
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      else if(0 == what) {
+        if(nonblocking) {
+          *done = FALSE;
+          return CURLE_OK;
+        }
+        else {
+          /* timeout */
+          failf(data, "SSL connection timeout");
+          return CURLE_OPERATION_TIMEDOUT;
+        }
+      }
+      /* socket is readable or writable */
+    }
+
+    /* Run transaction, and return to the caller if it failed or if
+     * this connection is part of a multi handle and this loop would
+     * execute again. This permits the owner of a multi handle to
+     * abort a connection attempt before step2 has completed while
+     * ensuring that a client using select() or epoll() will always
+     * have a valid fdset to wait on.
+     */
+    retcode = mbed_connect_step2(conn, sockindex);
+    if(retcode || (nonblocking &&
+                   (ssl_connect_2 == connssl->connecting_state ||
+                    ssl_connect_2_reading == connssl->connecting_state ||
+                    ssl_connect_2_writing == connssl->connecting_state)))
+      return retcode;
+
+  } /* repeat step2 until all transactions are done. */
+
+  if(ssl_connect_3 == connssl->connecting_state) {
+    retcode = mbed_connect_step3(conn, sockindex);
+    if(retcode)
+      return retcode;
+  }
+
+  if(ssl_connect_done == connssl->connecting_state) {
+    connssl->state = ssl_connection_complete;
+    conn->recv[sockindex] = mbed_recv;
+    conn->send[sockindex] = mbed_send;
+    *done = TRUE;
+  }
+  else
+    *done = FALSE;
+
+  /* Reset our connect state machine */
+  connssl->connecting_state = ssl_connect_1;
+
+  return CURLE_OK;
+}
+
+static CURLcode Curl_mbedtls_connect_nonblocking(struct connectdata *conn,
+                                                 int sockindex, bool *done)
+{
+  return mbed_connect_common(conn, sockindex, TRUE, done);
+}
+
+
+static CURLcode Curl_mbedtls_connect(struct connectdata *conn, int sockindex)
+{
+  CURLcode retcode;
+  bool done = FALSE;
+
+  retcode = mbed_connect_common(conn, sockindex, FALSE, &done);
+  if(retcode)
+    return retcode;
+
+  DEBUGASSERT(done);
+
+  return CURLE_OK;
+}
+
+/*
+ * return 0 error initializing SSL
+ * return 1 SSL initialized successfully
+ */
+static int Curl_mbedtls_init(void)
+{
+  return Curl_mbedtlsthreadlock_thread_setup();
+}
+
+static void Curl_mbedtls_cleanup(void)
+{
+  (void)Curl_mbedtlsthreadlock_thread_cleanup();
+}
+
+static bool Curl_mbedtls_data_pending(const struct connectdata *conn,
+                                      int sockindex)
+{
+  const struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  struct ssl_backend_data *backend = connssl->backend;
+  return mbedtls_ssl_get_bytes_avail(&backend->ssl) != 0;
+}
+
+static CURLcode Curl_mbedtls_sha256sum(const unsigned char *input,
+                                    size_t inputlen,
+                                    unsigned char *sha256sum,
+                                    size_t sha256len UNUSED_PARAM)
+{
+  (void)sha256len;
+#if MBEDTLS_VERSION_NUMBER < 0x02070000
+  mbedtls_sha256(input, inputlen, sha256sum, 0);
+#else
+  /* returns 0 on success, otherwise failure */
+  if(mbedtls_sha256_ret(input, inputlen, sha256sum, 0) != 0)
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+#endif
+  return CURLE_OK;
+}
+
+static void *Curl_mbedtls_get_internals(struct ssl_connect_data *connssl,
+                                        CURLINFO info UNUSED_PARAM)
+{
+  struct ssl_backend_data *backend = connssl->backend;
+  (void)info;
+  return &backend->ssl;
+}
+
+const struct Curl_ssl Curl_ssl_mbedtls = {
+  { CURLSSLBACKEND_MBEDTLS, "mbedtls" }, /* info */
+
+  SSLSUPP_CA_PATH |
+  SSLSUPP_PINNEDPUBKEY |
+  SSLSUPP_SSL_CTX,
+
+  sizeof(struct ssl_backend_data),
+
+  Curl_mbedtls_init,                /* init */
+  Curl_mbedtls_cleanup,             /* cleanup */
+  Curl_mbedtls_version,             /* version */
+  Curl_none_check_cxn,              /* check_cxn */
+  Curl_none_shutdown,               /* shutdown */
+  Curl_mbedtls_data_pending,        /* data_pending */
+  Curl_mbedtls_random,              /* random */
+  Curl_none_cert_status_request,    /* cert_status_request */
+  Curl_mbedtls_connect,             /* connect */
+  Curl_mbedtls_connect_nonblocking, /* connect_nonblocking */
+  Curl_mbedtls_get_internals,       /* get_internals */
+  Curl_mbedtls_close,               /* close_one */
+  Curl_mbedtls_close_all,           /* close_all */
+  Curl_mbedtls_session_free,        /* session_free */
+  Curl_none_set_engine,             /* set_engine */
+  Curl_none_set_engine_default,     /* set_engine_default */
+  Curl_none_engines_list,           /* engines_list */
+  Curl_none_false_start,            /* false_start */
+  Curl_none_md5sum,                 /* md5sum */
+  Curl_mbedtls_sha256sum            /* sha256sum */
+};
+
+#endif /* USE_MBEDTLS */