--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/lib/vtls/wolfssl.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,991 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2019, 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.haxx.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 wolfSSL 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_WOLFSSL
+
+#define WOLFSSL_OPTIONS_IGNORE_SYS
+#include <wolfssl/version.h>
+#include <wolfssl/options.h>
+
+/* To determine what functions are available we rely on one or both of:
+   - the user's options.h generated by wolfSSL
+   - the symbols detected by curl's configure
+   Since they are markedly different from one another, and one or the other may
+   not be available, we do some checking below to bring things in sync. */
+
+/* HAVE_ALPN is wolfSSL's build time symbol for enabling ALPN in options.h. */
+#ifndef HAVE_ALPN
+#ifdef HAVE_WOLFSSL_USEALPN
+#define HAVE_ALPN
+#endif
+#endif
+
+/* WOLFSSL_ALLOW_SSLV3 is wolfSSL's build time symbol for enabling SSLv3 in
+   options.h, but is only seen in >= 3.6.6 since that's when they started
+   disabling SSLv3 by default. */
+#ifndef WOLFSSL_ALLOW_SSLV3
+#if (LIBWOLFSSL_VERSION_HEX < 0x03006006) || \
+  defined(HAVE_WOLFSSLV3_CLIENT_METHOD)
+#define WOLFSSL_ALLOW_SSLV3
+#endif
+#endif
+
+#include <limits.h>
+
+#include "urldata.h"
+#include "sendf.h"
+#include "inet_pton.h"
+#include "vtls.h"
+#include "parsedate.h"
+#include "connect.h" /* for the connect timeout */
+#include "select.h"
+#include "strcase.h"
+#include "x509asn1.h"
+#include "curl_printf.h"
+#include "multiif.h"
+
+#include <wolfssl/openssl/ssl.h>
+#include <wolfssl/ssl.h>
+#include <wolfssl/error-ssl.h>
+#include "wolfssl.h"
+
+/* The last #include files should be: */
+#include "curl_memory.h"
+#include "memdebug.h"
+
+/* KEEP_PEER_CERT is a product of the presence of build time symbol
+   OPENSSL_EXTRA without NO_CERTS, depending on the version. KEEP_PEER_CERT is
+   in wolfSSL's settings.h, and the latter two are build time symbols in
+   options.h. */
+#ifndef KEEP_PEER_CERT
+#if defined(HAVE_WOLFSSL_GET_PEER_CERTIFICATE) || \
+    (defined(OPENSSL_EXTRA) && !defined(NO_CERTS))
+#define KEEP_PEER_CERT
+#endif
+#endif
+
+struct ssl_backend_data {
+  SSL_CTX* ctx;
+  SSL*     handle;
+};
+
+#define BACKEND connssl->backend
+
+static Curl_recv wolfssl_recv;
+static Curl_send wolfssl_send;
+
+
+static int do_file_type(const char *type)
+{
+  if(!type || !type[0])
+    return SSL_FILETYPE_PEM;
+  if(strcasecompare(type, "PEM"))
+    return SSL_FILETYPE_PEM;
+  if(strcasecompare(type, "DER"))
+    return SSL_FILETYPE_ASN1;
+  return -1;
+}
+
+/*
+ * This function loads all the client/CA certificates and CRLs. Setup the TLS
+ * layer and do all necessary magic.
+ */
+static CURLcode
+wolfssl_connect_step1(struct connectdata *conn,
+                     int sockindex)
+{
+  char *ciphers;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data* connssl = &conn->ssl[sockindex];
+  SSL_METHOD* req_method = NULL;
+  curl_socket_t sockfd = conn->sock[sockindex];
+#ifdef HAVE_SNI
+  bool sni = FALSE;
+#define use_sni(x)  sni = (x)
+#else
+#define use_sni(x)  Curl_nop_stmt
+#endif
+
+  if(connssl->state == ssl_connection_complete)
+    return CURLE_OK;
+
+  if(SSL_CONN_CONFIG(version_max) != CURL_SSLVERSION_MAX_NONE) {
+    failf(data, "wolfSSL does not support to set maximum SSL/TLS version");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  /* check to see if we've been told to use an explicit SSL/TLS version */
+  switch(SSL_CONN_CONFIG(version)) {
+  case CURL_SSLVERSION_DEFAULT:
+  case CURL_SSLVERSION_TLSv1:
+#if LIBWOLFSSL_VERSION_HEX >= 0x03003000 /* >= 3.3.0 */
+    /* minimum protocol version is set later after the CTX object is created */
+    req_method = SSLv23_client_method();
+#else
+    infof(data, "wolfSSL <3.3.0 cannot be configured to use TLS 1.0-1.2, "
+          "TLS 1.0 is used exclusively\n");
+    req_method = TLSv1_client_method();
+#endif
+    use_sni(TRUE);
+    break;
+  case CURL_SSLVERSION_TLSv1_0:
+#ifdef WOLFSSL_ALLOW_TLSV10
+    req_method = TLSv1_client_method();
+    use_sni(TRUE);
+#else
+    failf(data, "wolfSSL does not support TLS 1.0");
+    return CURLE_NOT_BUILT_IN;
+#endif
+    break;
+  case CURL_SSLVERSION_TLSv1_1:
+    req_method = TLSv1_1_client_method();
+    use_sni(TRUE);
+    break;
+  case CURL_SSLVERSION_TLSv1_2:
+    req_method = TLSv1_2_client_method();
+    use_sni(TRUE);
+    break;
+  case CURL_SSLVERSION_TLSv1_3:
+#ifdef WOLFSSL_TLS13
+    req_method = wolfTLSv1_3_client_method();
+    use_sni(TRUE);
+    break;
+#else
+    failf(data, "wolfSSL: TLS 1.3 is not yet supported");
+    return CURLE_SSL_CONNECT_ERROR;
+#endif
+  case CURL_SSLVERSION_SSLv3:
+#ifdef WOLFSSL_ALLOW_SSLV3
+    req_method = SSLv3_client_method();
+    use_sni(FALSE);
+#else
+    failf(data, "wolfSSL does not support SSLv3");
+    return CURLE_NOT_BUILT_IN;
+#endif
+    break;
+  case CURL_SSLVERSION_SSLv2:
+    failf(data, "wolfSSL does not support SSLv2");
+    return CURLE_SSL_CONNECT_ERROR;
+  default:
+    failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  if(!req_method) {
+    failf(data, "SSL: couldn't create a method!");
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  if(BACKEND->ctx)
+    SSL_CTX_free(BACKEND->ctx);
+  BACKEND->ctx = SSL_CTX_new(req_method);
+
+  if(!BACKEND->ctx) {
+    failf(data, "SSL: couldn't create a context!");
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  switch(SSL_CONN_CONFIG(version)) {
+  case CURL_SSLVERSION_DEFAULT:
+  case CURL_SSLVERSION_TLSv1:
+#if LIBWOLFSSL_VERSION_HEX > 0x03004006 /* > 3.4.6 */
+    /* Versions 3.3.0 to 3.4.6 we know the minimum protocol version is
+     * whatever minimum version of TLS was built in and at least TLS 1.0. For
+     * later library versions that could change (eg TLS 1.0 built in but
+     * defaults to TLS 1.1) so we have this short circuit evaluation to find
+     * the minimum supported TLS version.
+    */
+    if((wolfSSL_CTX_SetMinVersion(BACKEND->ctx, WOLFSSL_TLSV1) != 1) &&
+       (wolfSSL_CTX_SetMinVersion(BACKEND->ctx, WOLFSSL_TLSV1_1) != 1) &&
+       (wolfSSL_CTX_SetMinVersion(BACKEND->ctx, WOLFSSL_TLSV1_2) != 1)
+#ifdef WOLFSSL_TLS13
+       && (wolfSSL_CTX_SetMinVersion(BACKEND->ctx, WOLFSSL_TLSV1_3) != 1)
+#endif
+      ) {
+      failf(data, "SSL: couldn't set the minimum protocol version");
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+#endif
+    break;
+  }
+
+  ciphers = SSL_CONN_CONFIG(cipher_list);
+  if(ciphers) {
+    if(!SSL_CTX_set_cipher_list(BACKEND->ctx, ciphers)) {
+      failf(data, "failed setting cipher list: %s", ciphers);
+      return CURLE_SSL_CIPHER;
+    }
+    infof(data, "Cipher selection: %s\n", ciphers);
+  }
+
+#ifndef NO_FILESYSTEM
+  /* load trusted cacert */
+  if(SSL_CONN_CONFIG(CAfile)) {
+    if(1 != SSL_CTX_load_verify_locations(BACKEND->ctx,
+                                      SSL_CONN_CONFIG(CAfile),
+                                      SSL_CONN_CONFIG(CApath))) {
+      if(SSL_CONN_CONFIG(verifypeer)) {
+        /* Fail if we insist on successfully verifying the server. */
+        failf(data, "error setting certificate verify locations:\n"
+              "  CAfile: %s\n  CApath: %s",
+              SSL_CONN_CONFIG(CAfile)?
+              SSL_CONN_CONFIG(CAfile): "none",
+              SSL_CONN_CONFIG(CApath)?
+              SSL_CONN_CONFIG(CApath) : "none");
+        return CURLE_SSL_CACERT_BADFILE;
+      }
+      else {
+        /* Just continue with a warning if no strict certificate
+           verification is required. */
+        infof(data, "error setting certificate verify locations,"
+              " continuing anyway:\n");
+      }
+    }
+    else {
+      /* Everything is fine. */
+      infof(data, "successfully set certificate verify locations:\n");
+    }
+    infof(data,
+          "  CAfile: %s\n"
+          "  CApath: %s\n",
+          SSL_CONN_CONFIG(CAfile) ? SSL_CONN_CONFIG(CAfile):
+          "none",
+          SSL_CONN_CONFIG(CApath) ? SSL_CONN_CONFIG(CApath):
+          "none");
+  }
+
+  /* Load the client certificate, and private key */
+  if(SSL_SET_OPTION(cert) && SSL_SET_OPTION(key)) {
+    int file_type = do_file_type(SSL_SET_OPTION(cert_type));
+
+    if(SSL_CTX_use_certificate_file(BACKEND->ctx, SSL_SET_OPTION(cert),
+                                     file_type) != 1) {
+      failf(data, "unable to use client certificate (no key or wrong pass"
+            " phrase?)");
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+
+    file_type = do_file_type(SSL_SET_OPTION(key_type));
+    if(SSL_CTX_use_PrivateKey_file(BACKEND->ctx, SSL_SET_OPTION(key),
+                                    file_type) != 1) {
+      failf(data, "unable to set private key");
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+  }
+#endif /* !NO_FILESYSTEM */
+
+  /* SSL always tries to verify the peer, this only says whether it should
+   * 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_CONN_CONFIG(verifypeer)?SSL_VERIFY_PEER:
+                                                 SSL_VERIFY_NONE,
+                     NULL);
+
+#ifdef HAVE_SNI
+  if(sni) {
+    struct in_addr addr4;
+#ifdef ENABLE_IPV6
+    struct in6_addr addr6;
+#endif
+    const char * const hostname = SSL_IS_PROXY() ? conn->http_proxy.host.name :
+      conn->host.name;
+    size_t hostname_len = strlen(hostname);
+    if((hostname_len < USHRT_MAX) &&
+       (0 == Curl_inet_pton(AF_INET, hostname, &addr4)) &&
+#ifdef ENABLE_IPV6
+       (0 == Curl_inet_pton(AF_INET6, hostname, &addr6)) &&
+#endif
+       (wolfSSL_CTX_UseSNI(BACKEND->ctx, WOLFSSL_SNI_HOST_NAME, hostname,
+                          (unsigned short)hostname_len) != 1)) {
+      infof(data, "WARNING: failed to configure server name indication (SNI) "
+            "TLS extension\n");
+    }
+  }
+#endif
+
+  /* give application a chance to interfere with SSL set up. */
+  if(data->set.ssl.fsslctx) {
+    CURLcode result = (*data->set.ssl.fsslctx)(data, BACKEND->ctx,
+                                               data->set.ssl.fsslctxp);
+    if(result) {
+      failf(data, "error signaled by ssl ctx callback");
+      return result;
+    }
+  }
+#ifdef NO_FILESYSTEM
+  else if(SSL_CONN_CONFIG(verifypeer)) {
+    failf(data, "SSL: Certificates can't be loaded because wolfSSL was built"
+          " with \"no filesystem\". Either disable peer verification"
+          " (insecure) or if you are building an application with libcurl you"
+          " can load certificates via CURLOPT_SSL_CTX_FUNCTION.");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+#endif
+
+  /* Let's make an SSL structure */
+  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;
+  }
+
+#ifdef HAVE_ALPN
+  if(conn->bits.tls_enable_alpn) {
+    char protocols[128];
+    *protocols = '\0';
+
+    /* wolfSSL's ALPN protocol name list format is a comma separated string of
+       protocols in descending order of preference, eg: "h2,http/1.1" */
+
+#ifdef USE_NGHTTP2
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
+      strcpy(protocols + strlen(protocols), NGHTTP2_PROTO_VERSION_ID ",");
+      infof(data, "ALPN, offering %s\n", NGHTTP2_PROTO_VERSION_ID);
+    }
+#endif
+
+    strcpy(protocols + strlen(protocols), ALPN_HTTP_1_1);
+    infof(data, "ALPN, offering %s\n", ALPN_HTTP_1_1);
+
+    if(wolfSSL_UseALPN(BACKEND->handle, protocols,
+                       (unsigned)strlen(protocols),
+                       WOLFSSL_ALPN_CONTINUE_ON_MISMATCH) != SSL_SUCCESS) {
+      failf(data, "SSL: failed setting ALPN protocols");
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+  }
+#endif /* HAVE_ALPN */
+
+  /* Check if there's a cached ID we can/should use here! */
+  if(SSL_SET_OPTION(primary.sessionid)) {
+    void *ssl_sessionid = NULL;
+
+    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)) {
+        char error_buffer[WOLFSSL_MAX_ERROR_SZ];
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "SSL: SSL_set_session failed: %s",
+              ERR_error_string(SSL_get_error(BACKEND->handle, 0),
+                               error_buffer));
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      /* Informational message */
+      infof(data, "SSL re-using session ID\n");
+    }
+    Curl_ssl_sessionid_unlock(conn);
+  }
+
+  /* pass the raw socket into the SSL layer */
+  if(!SSL_set_fd(BACKEND->handle, (int)sockfd)) {
+    failf(data, "SSL: SSL_set_fd failed");
+    return CURLE_SSL_CONNECT_ERROR;
+  }
+
+  connssl->connecting_state = ssl_connect_2;
+  return CURLE_OK;
+}
+
+
+static CURLcode
+wolfssl_connect_step2(struct connectdata *conn,
+                     int sockindex)
+{
+  int ret = -1;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data* connssl = &conn->ssl[sockindex];
+  const char * const hostname = SSL_IS_PROXY() ? conn->http_proxy.host.name :
+    conn->host.name;
+  const char * const dispname = SSL_IS_PROXY() ?
+    conn->http_proxy.host.dispname : conn->host.dispname;
+  const char * const pinnedpubkey = SSL_IS_PROXY() ?
+                        data->set.str[STRING_SSL_PINNEDPUBLICKEY_PROXY] :
+                        data->set.str[STRING_SSL_PINNEDPUBLICKEY_ORIG];
+
+  conn->recv[sockindex] = wolfssl_recv;
+  conn->send[sockindex] = wolfssl_send;
+
+  /* Enable RFC2818 checks */
+  if(SSL_CONN_CONFIG(verifyhost)) {
+    ret = wolfSSL_check_domain_name(BACKEND->handle, hostname);
+    if(ret == SSL_FAILURE)
+      return CURLE_OUT_OF_MEMORY;
+  }
+
+  ret = SSL_connect(BACKEND->handle);
+  if(ret != 1) {
+    char error_buffer[WOLFSSL_MAX_ERROR_SZ];
+    int  detail = SSL_get_error(BACKEND->handle, ret);
+
+    if(SSL_ERROR_WANT_READ == detail) {
+      connssl->connecting_state = ssl_connect_2_reading;
+      return CURLE_OK;
+    }
+    else if(SSL_ERROR_WANT_WRITE == detail) {
+      connssl->connecting_state = ssl_connect_2_writing;
+      return CURLE_OK;
+    }
+    /* There is no easy way to override only the CN matching.
+     * This will enable the override of both mismatching SubjectAltNames
+     * as also mismatching CN fields */
+    else if(DOMAIN_NAME_MISMATCH == detail) {
+#if 1
+      failf(data, "\tsubject alt name(s) or common name do not match \"%s\"\n",
+            dispname);
+      return CURLE_PEER_FAILED_VERIFICATION;
+#else
+      /* When the wolfssl_check_domain_name() is used and you desire to
+       * continue on a DOMAIN_NAME_MISMATCH, i.e. 'conn->ssl_config.verifyhost
+       * == 0', CyaSSL version 2.4.0 will fail with an INCOMPLETE_DATA
+       * error. The only way to do this is currently to switch the
+       * Wolfssl_check_domain_name() in and out based on the
+       * 'conn->ssl_config.verifyhost' value. */
+      if(SSL_CONN_CONFIG(verifyhost)) {
+        failf(data,
+              "\tsubject alt name(s) or common name do not match \"%s\"\n",
+              dispname);
+        return CURLE_PEER_FAILED_VERIFICATION;
+      }
+      else {
+        infof(data,
+              "\tsubject alt name(s) and/or common name do not match \"%s\"\n",
+              dispname);
+        return CURLE_OK;
+      }
+#endif
+    }
+#if LIBWOLFSSL_VERSION_HEX >= 0x02007000 /* 2.7.0 */
+    else if(ASN_NO_SIGNER_E == detail) {
+      if(SSL_CONN_CONFIG(verifypeer)) {
+        failf(data, "\tCA signer not available for verification\n");
+        return CURLE_SSL_CACERT_BADFILE;
+      }
+      else {
+        /* Just continue with a warning if no strict certificate
+           verification is required. */
+        infof(data, "CA signer not available for verification, "
+                    "continuing anyway\n");
+      }
+    }
+#endif
+    else {
+      failf(data, "SSL_connect failed with error %d: %s", detail,
+          ERR_error_string(detail, error_buffer));
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+  }
+
+  if(pinnedpubkey) {
+#ifdef KEEP_PEER_CERT
+    X509 *x509;
+    const char *x509_der;
+    int x509_der_len;
+    curl_X509certificate x509_parsed;
+    curl_asn1Element *pubkey;
+    CURLcode result;
+
+    x509 = SSL_get_peer_certificate(BACKEND->handle);
+    if(!x509) {
+      failf(data, "SSL: failed retrieving server certificate");
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    x509_der = (const char *)wolfSSL_X509_get_der(x509, &x509_der_len);
+    if(!x509_der) {
+      failf(data, "SSL: failed retrieving ASN.1 server certificate");
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    memset(&x509_parsed, 0, sizeof(x509_parsed));
+    if(Curl_parseX509(&x509_parsed, x509_der, x509_der + x509_der_len))
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+
+    pubkey = &x509_parsed.subjectPublicKeyInfo;
+    if(!pubkey->header || pubkey->end <= pubkey->header) {
+      failf(data, "SSL: failed retrieving public key from server certificate");
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+    }
+
+    result = Curl_pin_peer_pubkey(data,
+                                  pinnedpubkey,
+                                  (const unsigned char *)pubkey->header,
+                                  (size_t)(pubkey->end - pubkey->header));
+    if(result) {
+      failf(data, "SSL: public key does not match pinned public key!");
+      return result;
+    }
+#else
+    failf(data, "Library lacks pinning support built-in");
+    return CURLE_NOT_BUILT_IN;
+#endif
+  }
+
+#ifdef HAVE_ALPN
+  if(conn->bits.tls_enable_alpn) {
+    int rc;
+    char *protocol = NULL;
+    unsigned short protocol_len = 0;
+
+    rc = wolfSSL_ALPN_GetProtocol(BACKEND->handle, &protocol, &protocol_len);
+
+    if(rc == SSL_SUCCESS) {
+      infof(data, "ALPN, server accepted to use %.*s\n", protocol_len,
+            protocol);
+
+      if(protocol_len == ALPN_HTTP_1_1_LENGTH &&
+         !memcmp(protocol, ALPN_HTTP_1_1, ALPN_HTTP_1_1_LENGTH))
+        conn->negnpn = CURL_HTTP_VERSION_1_1;
+#ifdef USE_NGHTTP2
+      else if(data->set.httpversion >= CURL_HTTP_VERSION_2 &&
+              protocol_len == NGHTTP2_PROTO_VERSION_ID_LEN &&
+              !memcmp(protocol, NGHTTP2_PROTO_VERSION_ID,
+                      NGHTTP2_PROTO_VERSION_ID_LEN))
+        conn->negnpn = CURL_HTTP_VERSION_2;
+#endif
+      else
+        infof(data, "ALPN, unrecognized protocol %.*s\n", protocol_len,
+              protocol);
+      Curl_multiuse_state(conn, conn->negnpn == CURL_HTTP_VERSION_2 ?
+                          BUNDLE_MULTIPLEX : BUNDLE_NO_MULTIUSE);
+    }
+    else if(rc == SSL_ALPN_NOT_FOUND)
+      infof(data, "ALPN, server did not agree to a protocol\n");
+    else {
+      failf(data, "ALPN, failure getting protocol, error %d", rc);
+      return CURLE_SSL_CONNECT_ERROR;
+    }
+  }
+#endif /* HAVE_ALPN */
+
+  connssl->connecting_state = ssl_connect_3;
+#if (LIBWOLFSSL_VERSION_HEX >= 0x03009010)
+  infof(data, "SSL connection using %s / %s\n",
+        wolfSSL_get_version(BACKEND->handle),
+        wolfSSL_get_cipher_name(BACKEND->handle));
+#else
+  infof(data, "SSL connected\n");
+#endif
+
+  return CURLE_OK;
+}
+
+
+static CURLcode
+wolfssl_connect_step3(struct connectdata *conn,
+                     int sockindex)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+
+  DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
+
+  if(SSL_SET_OPTION(primary.sessionid)) {
+    bool incache;
+    SSL_SESSION *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
+
+    our_ssl_sessionid = SSL_get_session(BACKEND->handle);
+
+    Curl_ssl_sessionid_lock(conn);
+    incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL,
+                                      sockindex));
+    if(incache) {
+      if(old_ssl_sessionid != our_ssl_sessionid) {
+        infof(data, "old SSL session ID is stale, removing\n");
+        Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+        incache = FALSE;
+      }
+    }
+
+    if(!incache) {
+      result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
+                                     0 /* unknown size */, sockindex);
+      if(result) {
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "failed to store ssl session");
+        return result;
+      }
+    }
+    Curl_ssl_sessionid_unlock(conn);
+  }
+
+  connssl->connecting_state = ssl_connect_done;
+
+  return result;
+}
+
+
+static ssize_t wolfssl_send(struct connectdata *conn,
+                           int sockindex,
+                           const void *mem,
+                           size_t len,
+                           CURLcode *curlcode)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  char error_buffer[WOLFSSL_MAX_ERROR_SZ];
+  int  memlen = (len > (size_t)INT_MAX) ? INT_MAX : (int)len;
+  int  rc     = SSL_write(BACKEND->handle, mem, memlen);
+
+  if(rc < 0) {
+    int err = SSL_get_error(BACKEND->handle, rc);
+
+    switch(err) {
+    case SSL_ERROR_WANT_READ:
+    case SSL_ERROR_WANT_WRITE:
+      /* there's data pending, re-invoke SSL_write() */
+      *curlcode = CURLE_AGAIN;
+      return -1;
+    default:
+      failf(conn->data, "SSL write: %s, errno %d",
+            ERR_error_string(err, error_buffer),
+            SOCKERRNO);
+      *curlcode = CURLE_SEND_ERROR;
+      return -1;
+    }
+  }
+  return rc;
+}
+
+static void Curl_wolfssl_close(struct connectdata *conn, int sockindex)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+
+  if(BACKEND->handle) {
+    (void)SSL_shutdown(BACKEND->handle);
+    SSL_free(BACKEND->handle);
+    BACKEND->handle = NULL;
+  }
+  if(BACKEND->ctx) {
+    SSL_CTX_free(BACKEND->ctx);
+    BACKEND->ctx = NULL;
+  }
+}
+
+static ssize_t wolfssl_recv(struct connectdata *conn,
+                           int num,
+                           char *buf,
+                           size_t buffersize,
+                           CURLcode *curlcode)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[num];
+  char error_buffer[WOLFSSL_MAX_ERROR_SZ];
+  int  buffsize = (buffersize > (size_t)INT_MAX) ? INT_MAX : (int)buffersize;
+  int  nread    = SSL_read(BACKEND->handle, buf, buffsize);
+
+  if(nread < 0) {
+    int err = SSL_get_error(BACKEND->handle, nread);
+
+    switch(err) {
+    case SSL_ERROR_ZERO_RETURN: /* no more data */
+      break;
+    case SSL_ERROR_WANT_READ:
+    case SSL_ERROR_WANT_WRITE:
+      /* there's data pending, re-invoke SSL_read() */
+      *curlcode = CURLE_AGAIN;
+      return -1;
+    default:
+      failf(conn->data, "SSL read: %s, errno %d",
+            ERR_error_string(err, error_buffer),
+            SOCKERRNO);
+      *curlcode = CURLE_RECV_ERROR;
+      return -1;
+    }
+  }
+  return nread;
+}
+
+
+static void Curl_wolfssl_session_free(void *ptr)
+{
+  (void)ptr;
+  /* wolfSSL reuses sessions on own, no free */
+}
+
+
+static size_t Curl_wolfssl_version(char *buffer, size_t size)
+{
+#if LIBWOLFSSL_VERSION_HEX >= 0x03006000
+  return msnprintf(buffer, size, "wolfSSL/%s", wolfSSL_lib_version());
+#elif defined(WOLFSSL_VERSION)
+  return msnprintf(buffer, size, "wolfSSL/%s", WOLFSSL_VERSION);
+#endif
+}
+
+
+static int Curl_wolfssl_init(void)
+{
+  return (wolfSSL_Init() == SSL_SUCCESS);
+}
+
+
+static void Curl_wolfssl_cleanup(void)
+{
+  wolfSSL_Cleanup();
+}
+
+
+static bool Curl_wolfssl_data_pending(const struct connectdata* conn,
+                                     int connindex)
+{
+  const struct ssl_connect_data *connssl = &conn->ssl[connindex];
+  if(BACKEND->handle)   /* SSL is in use */
+    return (0 != SSL_pending(BACKEND->handle)) ? TRUE : FALSE;
+  else
+    return FALSE;
+}
+
+
+/*
+ * This function is called to shut down the SSL layer but keep the
+ * socket open (CCC - Clear Command Channel)
+ */
+static int Curl_wolfssl_shutdown(struct connectdata *conn, int sockindex)
+{
+  int retval = 0;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+
+  if(BACKEND->handle) {
+    SSL_free(BACKEND->handle);
+    BACKEND->handle = NULL;
+  }
+  return retval;
+}
+
+
+static CURLcode
+wolfssl_connect_common(struct connectdata *conn,
+                      int sockindex,
+                      bool nonblocking,
+                      bool *done)
+{
+  CURLcode result;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  curl_socket_t sockfd = conn->sock[sockindex];
+  time_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;
+    }
+
+    result = wolfssl_connect_step1(conn, sockindex);
+    if(result)
+      return result;
+  }
+
+  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.
+     */
+    result = wolfssl_connect_step2(conn, sockindex);
+    if(result || (nonblocking &&
+                  (ssl_connect_2 == connssl->connecting_state ||
+                   ssl_connect_2_reading == connssl->connecting_state ||
+                   ssl_connect_2_writing == connssl->connecting_state)))
+      return result;
+  } /* repeat step2 until all transactions are done. */
+
+  if(ssl_connect_3 == connssl->connecting_state) {
+    result = wolfssl_connect_step3(conn, sockindex);
+    if(result)
+      return result;
+  }
+
+  if(ssl_connect_done == connssl->connecting_state) {
+    connssl->state = ssl_connection_complete;
+    conn->recv[sockindex] = wolfssl_recv;
+    conn->send[sockindex] = wolfssl_send;
+    *done = TRUE;
+  }
+  else
+    *done = FALSE;
+
+  /* Reset our connect state machine */
+  connssl->connecting_state = ssl_connect_1;
+
+  return CURLE_OK;
+}
+
+
+static CURLcode Curl_wolfssl_connect_nonblocking(struct connectdata *conn,
+                                                int sockindex, bool *done)
+{
+  return wolfssl_connect_common(conn, sockindex, TRUE, done);
+}
+
+
+static CURLcode Curl_wolfssl_connect(struct connectdata *conn, int sockindex)
+{
+  CURLcode result;
+  bool done = FALSE;
+
+  result = wolfssl_connect_common(conn, sockindex, FALSE, &done);
+  if(result)
+    return result;
+
+  DEBUGASSERT(done);
+
+  return CURLE_OK;
+}
+
+static CURLcode Curl_wolfssl_random(struct Curl_easy *data,
+                                   unsigned char *entropy, size_t length)
+{
+  RNG rng;
+  (void)data;
+  if(wc_InitRng(&rng))
+    return CURLE_FAILED_INIT;
+  if(length > UINT_MAX)
+    return CURLE_FAILED_INIT;
+  if(wc_RNG_GenerateBlock(&rng, entropy, (unsigned)length))
+    return CURLE_FAILED_INIT;
+  if(wc_FreeRng(&rng))
+    return CURLE_FAILED_INIT;
+  return CURLE_OK;
+}
+
+static CURLcode Curl_wolfssl_sha256sum(const unsigned char *tmp, /* input */
+                                  size_t tmplen,
+                                  unsigned char *sha256sum /* output */,
+                                  size_t unused)
+{
+  Sha256 SHA256pw;
+  (void)unused;
+  wc_InitSha256(&SHA256pw);
+  wc_Sha256Update(&SHA256pw, tmp, (word32)tmplen);
+  wc_Sha256Final(&SHA256pw, sha256sum);
+  return CURLE_OK;
+}
+
+static void *Curl_wolfssl_get_internals(struct ssl_connect_data *connssl,
+                                       CURLINFO info UNUSED_PARAM)
+{
+  (void)info;
+  return BACKEND->handle;
+}
+
+const struct Curl_ssl Curl_ssl_wolfssl = {
+  { CURLSSLBACKEND_WOLFSSL, "WolfSSL" }, /* info */
+
+#ifdef KEEP_PEER_CERT
+  SSLSUPP_PINNEDPUBKEY |
+#endif
+  SSLSUPP_SSL_CTX,
+
+  sizeof(struct ssl_backend_data),
+
+  Curl_wolfssl_init,                /* init */
+  Curl_wolfssl_cleanup,             /* cleanup */
+  Curl_wolfssl_version,             /* version */
+  Curl_none_check_cxn,             /* check_cxn */
+  Curl_wolfssl_shutdown,            /* shutdown */
+  Curl_wolfssl_data_pending,        /* data_pending */
+  Curl_wolfssl_random,              /* random */
+  Curl_none_cert_status_request,   /* cert_status_request */
+  Curl_wolfssl_connect,             /* connect */
+  Curl_wolfssl_connect_nonblocking, /* connect_nonblocking */
+  Curl_wolfssl_get_internals,       /* get_internals */
+  Curl_wolfssl_close,               /* close_one */
+  Curl_none_close_all,             /* close_all */
+  Curl_wolfssl_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_wolfssl_sha256sum            /* sha256sum */
+};
+
+#endif