--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/lib/vtls/vtls.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,1343 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  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.
+ *
+ ***************************************************************************/
+
+/* This file is for implementing all "generic" SSL functions that all libcurl
+   internals should use. It is then responsible for calling the proper
+   "backend" function.
+
+   SSL-functions in libcurl should call functions in this source file, and not
+   to any specific SSL-layer.
+
+   Curl_ssl_ - prefix for generic ones
+
+   Note that this source code uses the functions of the configured SSL
+   backend via the global Curl_ssl instance.
+
+   "SSL/TLS Strong Encryption: An Introduction"
+   https://httpd.apache.org/docs/2.0/ssl/ssl_intro.html
+*/
+
+#include "curl_setup.h"
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#include "urldata.h"
+
+#include "vtls.h" /* generic SSL protos etc */
+#include "slist.h"
+#include "sendf.h"
+#include "strcase.h"
+#include "url.h"
+#include "progress.h"
+#include "share.h"
+#include "multiif.h"
+#include "timeval.h"
+#include "curl_md5.h"
+#include "warnless.h"
+#include "curl_base64.h"
+#include "curl_printf.h"
+
+/* The last #include files should be: */
+#include "curl_memory.h"
+#include "memdebug.h"
+
+/* convenience macro to check if this handle is using a shared SSL session */
+#define SSLSESSION_SHARED(data) (data->share &&                        \
+                                 (data->share->specifier &             \
+                                  (1<<CURL_LOCK_DATA_SSL_SESSION)))
+
+#define CLONE_STRING(var)                    \
+  if(source->var) {                          \
+    dest->var = strdup(source->var);         \
+    if(!dest->var)                           \
+      return FALSE;                          \
+  }                                          \
+  else                                       \
+    dest->var = NULL;
+
+bool
+Curl_ssl_config_matches(struct ssl_primary_config* data,
+                        struct ssl_primary_config* needle)
+{
+  if((data->version == needle->version) &&
+     (data->version_max == needle->version_max) &&
+     (data->verifypeer == needle->verifypeer) &&
+     (data->verifyhost == needle->verifyhost) &&
+     (data->verifystatus == needle->verifystatus) &&
+     Curl_safe_strcasecompare(data->CApath, needle->CApath) &&
+     Curl_safe_strcasecompare(data->CAfile, needle->CAfile) &&
+     Curl_safe_strcasecompare(data->clientcert, needle->clientcert) &&
+     Curl_safe_strcasecompare(data->random_file, needle->random_file) &&
+     Curl_safe_strcasecompare(data->egdsocket, needle->egdsocket) &&
+     Curl_safe_strcasecompare(data->cipher_list, needle->cipher_list) &&
+     Curl_safe_strcasecompare(data->cipher_list13, needle->cipher_list13))
+    return TRUE;
+
+  return FALSE;
+}
+
+bool
+Curl_clone_primary_ssl_config(struct ssl_primary_config *source,
+                              struct ssl_primary_config *dest)
+{
+  dest->version = source->version;
+  dest->version_max = source->version_max;
+  dest->verifypeer = source->verifypeer;
+  dest->verifyhost = source->verifyhost;
+  dest->verifystatus = source->verifystatus;
+  dest->sessionid = source->sessionid;
+
+  CLONE_STRING(CApath);
+  CLONE_STRING(CAfile);
+  CLONE_STRING(clientcert);
+  CLONE_STRING(random_file);
+  CLONE_STRING(egdsocket);
+  CLONE_STRING(cipher_list);
+  CLONE_STRING(cipher_list13);
+
+  return TRUE;
+}
+
+void Curl_free_primary_ssl_config(struct ssl_primary_config* sslc)
+{
+  Curl_safefree(sslc->CApath);
+  Curl_safefree(sslc->CAfile);
+  Curl_safefree(sslc->clientcert);
+  Curl_safefree(sslc->random_file);
+  Curl_safefree(sslc->egdsocket);
+  Curl_safefree(sslc->cipher_list);
+  Curl_safefree(sslc->cipher_list13);
+}
+
+#ifdef USE_SSL
+static int multissl_init(const struct Curl_ssl *backend);
+#endif
+
+int Curl_ssl_backend(void)
+{
+#ifdef USE_SSL
+  multissl_init(NULL);
+  return Curl_ssl->info.id;
+#else
+  return (int)CURLSSLBACKEND_NONE;
+#endif
+}
+
+#ifdef USE_SSL
+
+/* "global" init done? */
+static bool init_ssl = FALSE;
+
+/**
+ * Global SSL init
+ *
+ * @retval 0 error initializing SSL
+ * @retval 1 SSL initialized successfully
+ */
+int Curl_ssl_init(void)
+{
+  /* make sure this is only done once */
+  if(init_ssl)
+    return 1;
+  init_ssl = TRUE; /* never again */
+
+  return Curl_ssl->init();
+}
+
+
+/* Global cleanup */
+void Curl_ssl_cleanup(void)
+{
+  if(init_ssl) {
+    /* only cleanup if we did a previous init */
+    Curl_ssl->cleanup();
+    init_ssl = FALSE;
+  }
+}
+
+static bool ssl_prefs_check(struct Curl_easy *data)
+{
+  /* check for CURLOPT_SSLVERSION invalid parameter value */
+  const long sslver = data->set.ssl.primary.version;
+  if((sslver < 0) || (sslver >= CURL_SSLVERSION_LAST)) {
+    failf(data, "Unrecognized parameter value passed via CURLOPT_SSLVERSION");
+    return FALSE;
+  }
+
+  switch(data->set.ssl.primary.version_max) {
+  case CURL_SSLVERSION_MAX_NONE:
+  case CURL_SSLVERSION_MAX_DEFAULT:
+    break;
+
+  default:
+    if((data->set.ssl.primary.version_max >> 16) < sslver) {
+      failf(data, "CURL_SSLVERSION_MAX incompatible with CURL_SSLVERSION");
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+
+static CURLcode
+ssl_connect_init_proxy(struct connectdata *conn, int sockindex)
+{
+  DEBUGASSERT(conn->bits.proxy_ssl_connected[sockindex]);
+  if(ssl_connection_complete == conn->ssl[sockindex].state &&
+     !conn->proxy_ssl[sockindex].use) {
+    struct ssl_backend_data *pbdata;
+
+    if(!(Curl_ssl->supports & SSLSUPP_HTTPS_PROXY))
+      return CURLE_NOT_BUILT_IN;
+
+    /* The pointers to the ssl backend data, which is opaque here, are swapped
+       rather than move the contents. */
+    pbdata = conn->proxy_ssl[sockindex].backend;
+    conn->proxy_ssl[sockindex] = conn->ssl[sockindex];
+
+    memset(&conn->ssl[sockindex], 0, sizeof(conn->ssl[sockindex]));
+    memset(pbdata, 0, Curl_ssl->sizeof_ssl_backend_data);
+
+    conn->ssl[sockindex].backend = pbdata;
+  }
+  return CURLE_OK;
+}
+
+CURLcode
+Curl_ssl_connect(struct connectdata *conn, int sockindex)
+{
+  CURLcode result;
+
+  if(conn->bits.proxy_ssl_connected[sockindex]) {
+    result = ssl_connect_init_proxy(conn, sockindex);
+    if(result)
+      return result;
+  }
+
+  if(!ssl_prefs_check(conn->data))
+    return CURLE_SSL_CONNECT_ERROR;
+
+  /* mark this is being ssl-enabled from here on. */
+  conn->ssl[sockindex].use = TRUE;
+  conn->ssl[sockindex].state = ssl_connection_negotiating;
+
+  result = Curl_ssl->connect_blocking(conn, sockindex);
+
+  if(!result)
+    Curl_pgrsTime(conn->data, TIMER_APPCONNECT); /* SSL is connected */
+
+  return result;
+}
+
+CURLcode
+Curl_ssl_connect_nonblocking(struct connectdata *conn, int sockindex,
+                             bool *done)
+{
+  CURLcode result;
+  if(conn->bits.proxy_ssl_connected[sockindex]) {
+    result = ssl_connect_init_proxy(conn, sockindex);
+    if(result)
+      return result;
+  }
+
+  if(!ssl_prefs_check(conn->data))
+    return CURLE_SSL_CONNECT_ERROR;
+
+  /* mark this is being ssl requested from here on. */
+  conn->ssl[sockindex].use = TRUE;
+  result = Curl_ssl->connect_nonblocking(conn, sockindex, done);
+  if(!result && *done)
+    Curl_pgrsTime(conn->data, TIMER_APPCONNECT); /* SSL is connected */
+  return result;
+}
+
+/*
+ * Lock shared SSL session data
+ */
+void Curl_ssl_sessionid_lock(struct connectdata *conn)
+{
+  if(SSLSESSION_SHARED(conn->data))
+    Curl_share_lock(conn->data,
+                    CURL_LOCK_DATA_SSL_SESSION, CURL_LOCK_ACCESS_SINGLE);
+}
+
+/*
+ * Unlock shared SSL session data
+ */
+void Curl_ssl_sessionid_unlock(struct connectdata *conn)
+{
+  if(SSLSESSION_SHARED(conn->data))
+    Curl_share_unlock(conn->data, CURL_LOCK_DATA_SSL_SESSION);
+}
+
+/*
+ * Check if there's a session ID for the given connection in the cache, and if
+ * there's one suitable, it is provided. Returns TRUE when no entry matched.
+ */
+bool Curl_ssl_getsessionid(struct connectdata *conn,
+                           void **ssl_sessionid,
+                           size_t *idsize, /* set 0 if unknown */
+                           int sockindex)
+{
+  struct curl_ssl_session *check;
+  struct Curl_easy *data = conn->data;
+  size_t i;
+  long *general_age;
+  bool no_match = TRUE;
+
+  const bool isProxy = CONNECT_PROXY_SSL();
+  struct ssl_primary_config * const ssl_config = isProxy ?
+    &conn->proxy_ssl_config :
+    &conn->ssl_config;
+  const char * const name = isProxy ? conn->http_proxy.host.name :
+    conn->host.name;
+  int port = isProxy ? (int)conn->port : conn->remote_port;
+  *ssl_sessionid = NULL;
+
+  DEBUGASSERT(SSL_SET_OPTION(primary.sessionid));
+
+  if(!SSL_SET_OPTION(primary.sessionid))
+    /* session ID re-use is disabled */
+    return TRUE;
+
+  /* Lock if shared */
+  if(SSLSESSION_SHARED(data))
+    general_age = &data->share->sessionage;
+  else
+    general_age = &data->state.sessionage;
+
+  for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++) {
+    check = &data->state.session[i];
+    if(!check->sessionid)
+      /* not session ID means blank entry */
+      continue;
+    if(strcasecompare(name, check->name) &&
+       ((!conn->bits.conn_to_host && !check->conn_to_host) ||
+        (conn->bits.conn_to_host && check->conn_to_host &&
+         strcasecompare(conn->conn_to_host.name, check->conn_to_host))) &&
+       ((!conn->bits.conn_to_port && check->conn_to_port == -1) ||
+        (conn->bits.conn_to_port && check->conn_to_port != -1 &&
+         conn->conn_to_port == check->conn_to_port)) &&
+       (port == check->remote_port) &&
+       strcasecompare(conn->handler->scheme, check->scheme) &&
+       Curl_ssl_config_matches(ssl_config, &check->ssl_config)) {
+      /* yes, we have a session ID! */
+      (*general_age)++;          /* increase general age */
+      check->age = *general_age; /* set this as used in this age */
+      *ssl_sessionid = check->sessionid;
+      if(idsize)
+        *idsize = check->idsize;
+      no_match = FALSE;
+      break;
+    }
+  }
+
+  return no_match;
+}
+
+/*
+ * Kill a single session ID entry in the cache.
+ */
+void Curl_ssl_kill_session(struct curl_ssl_session *session)
+{
+  if(session->sessionid) {
+    /* defensive check */
+
+    /* free the ID the SSL-layer specific way */
+    Curl_ssl->session_free(session->sessionid);
+
+    session->sessionid = NULL;
+    session->age = 0; /* fresh */
+
+    Curl_free_primary_ssl_config(&session->ssl_config);
+
+    Curl_safefree(session->name);
+    Curl_safefree(session->conn_to_host);
+  }
+}
+
+/*
+ * Delete the given session ID from the cache.
+ */
+void Curl_ssl_delsessionid(struct connectdata *conn, void *ssl_sessionid)
+{
+  size_t i;
+  struct Curl_easy *data = conn->data;
+
+  for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++) {
+    struct curl_ssl_session *check = &data->state.session[i];
+
+    if(check->sessionid == ssl_sessionid) {
+      Curl_ssl_kill_session(check);
+      break;
+    }
+  }
+}
+
+/*
+ * Store session id in the session cache. The ID passed on to this function
+ * must already have been extracted and allocated the proper way for the SSL
+ * layer. Curl_XXXX_session_free() will be called to free/kill the session ID
+ * later on.
+ */
+CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
+                               void *ssl_sessionid,
+                               size_t idsize,
+                               int sockindex)
+{
+  size_t i;
+  struct Curl_easy *data = conn->data; /* the mother of all structs */
+  struct curl_ssl_session *store = &data->state.session[0];
+  long oldest_age = data->state.session[0].age; /* zero if unused */
+  char *clone_host;
+  char *clone_conn_to_host;
+  int conn_to_port;
+  long *general_age;
+  const bool isProxy = CONNECT_PROXY_SSL();
+  struct ssl_primary_config * const ssl_config = isProxy ?
+    &conn->proxy_ssl_config :
+    &conn->ssl_config;
+
+  DEBUGASSERT(SSL_SET_OPTION(primary.sessionid));
+
+  clone_host = strdup(isProxy ? conn->http_proxy.host.name : conn->host.name);
+  if(!clone_host)
+    return CURLE_OUT_OF_MEMORY; /* bail out */
+
+  if(conn->bits.conn_to_host) {
+    clone_conn_to_host = strdup(conn->conn_to_host.name);
+    if(!clone_conn_to_host) {
+      free(clone_host);
+      return CURLE_OUT_OF_MEMORY; /* bail out */
+    }
+  }
+  else
+    clone_conn_to_host = NULL;
+
+  if(conn->bits.conn_to_port)
+    conn_to_port = conn->conn_to_port;
+  else
+    conn_to_port = -1;
+
+  /* Now we should add the session ID and the host name to the cache, (remove
+     the oldest if necessary) */
+
+  /* If using shared SSL session, lock! */
+  if(SSLSESSION_SHARED(data)) {
+    general_age = &data->share->sessionage;
+  }
+  else {
+    general_age = &data->state.sessionage;
+  }
+
+  /* find an empty slot for us, or find the oldest */
+  for(i = 1; (i < data->set.general_ssl.max_ssl_sessions) &&
+        data->state.session[i].sessionid; i++) {
+    if(data->state.session[i].age < oldest_age) {
+      oldest_age = data->state.session[i].age;
+      store = &data->state.session[i];
+    }
+  }
+  if(i == data->set.general_ssl.max_ssl_sessions)
+    /* cache is full, we must "kill" the oldest entry! */
+    Curl_ssl_kill_session(store);
+  else
+    store = &data->state.session[i]; /* use this slot */
+
+  /* now init the session struct wisely */
+  store->sessionid = ssl_sessionid;
+  store->idsize = idsize;
+  store->age = *general_age;    /* set current age */
+  /* free it if there's one already present */
+  free(store->name);
+  free(store->conn_to_host);
+  store->name = clone_host;               /* clone host name */
+  store->conn_to_host = clone_conn_to_host; /* clone connect to host name */
+  store->conn_to_port = conn_to_port; /* connect to port number */
+  /* port number */
+  store->remote_port = isProxy ? (int)conn->port : conn->remote_port;
+  store->scheme = conn->handler->scheme;
+
+  if(!Curl_clone_primary_ssl_config(ssl_config, &store->ssl_config)) {
+    store->sessionid = NULL; /* let caller free sessionid */
+    free(clone_host);
+    free(clone_conn_to_host);
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  return CURLE_OK;
+}
+
+
+void Curl_ssl_close_all(struct Curl_easy *data)
+{
+  /* kill the session ID cache if not shared */
+  if(data->state.session && !SSLSESSION_SHARED(data)) {
+    size_t i;
+    for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++)
+      /* the single-killer function handles empty table slots */
+      Curl_ssl_kill_session(&data->state.session[i]);
+
+    /* free the cache data */
+    Curl_safefree(data->state.session);
+  }
+
+  Curl_ssl->close_all(data);
+}
+
+#if defined(USE_OPENSSL) || defined(USE_GNUTLS) || defined(USE_SCHANNEL) || \
+  defined(USE_SECTRANSP) || defined(USE_POLARSSL) || defined(USE_NSS) || \
+  defined(USE_MBEDTLS) || defined(USE_WOLFSSL)
+int Curl_ssl_getsock(struct connectdata *conn, curl_socket_t *socks)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[FIRSTSOCKET];
+
+  if(connssl->connecting_state == ssl_connect_2_writing) {
+    /* write mode */
+    socks[0] = conn->sock[FIRSTSOCKET];
+    return GETSOCK_WRITESOCK(0);
+  }
+  if(connssl->connecting_state == ssl_connect_2_reading) {
+    /* read mode */
+    socks[0] = conn->sock[FIRSTSOCKET];
+    return GETSOCK_READSOCK(0);
+  }
+
+  return GETSOCK_BLANK;
+}
+#else
+int Curl_ssl_getsock(struct connectdata *conn,
+                     curl_socket_t *socks)
+{
+  (void)conn;
+  (void)socks;
+  return GETSOCK_BLANK;
+}
+/* USE_OPENSSL || USE_GNUTLS || USE_SCHANNEL || USE_SECTRANSP || USE_NSS */
+#endif
+
+void Curl_ssl_close(struct connectdata *conn, int sockindex)
+{
+  DEBUGASSERT((sockindex <= 1) && (sockindex >= -1));
+  Curl_ssl->close_one(conn, sockindex);
+}
+
+CURLcode Curl_ssl_shutdown(struct connectdata *conn, int sockindex)
+{
+  if(Curl_ssl->shut_down(conn, sockindex))
+    return CURLE_SSL_SHUTDOWN_FAILED;
+
+  conn->ssl[sockindex].use = FALSE; /* get back to ordinary socket usage */
+  conn->ssl[sockindex].state = ssl_connection_none;
+
+  conn->recv[sockindex] = Curl_recv_plain;
+  conn->send[sockindex] = Curl_send_plain;
+
+  return CURLE_OK;
+}
+
+/* Selects an SSL crypto engine
+ */
+CURLcode Curl_ssl_set_engine(struct Curl_easy *data, const char *engine)
+{
+  return Curl_ssl->set_engine(data, engine);
+}
+
+/* Selects the default SSL crypto engine
+ */
+CURLcode Curl_ssl_set_engine_default(struct Curl_easy *data)
+{
+  return Curl_ssl->set_engine_default(data);
+}
+
+/* Return list of OpenSSL crypto engine names. */
+struct curl_slist *Curl_ssl_engines_list(struct Curl_easy *data)
+{
+  return Curl_ssl->engines_list(data);
+}
+
+/*
+ * This sets up a session ID cache to the specified size. Make sure this code
+ * is agnostic to what underlying SSL technology we use.
+ */
+CURLcode Curl_ssl_initsessions(struct Curl_easy *data, size_t amount)
+{
+  struct curl_ssl_session *session;
+
+  if(data->state.session)
+    /* this is just a precaution to prevent multiple inits */
+    return CURLE_OK;
+
+  session = calloc(amount, sizeof(struct curl_ssl_session));
+  if(!session)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* store the info in the SSL section */
+  data->set.general_ssl.max_ssl_sessions = amount;
+  data->state.session = session;
+  data->state.sessionage = 1; /* this is brand new */
+  return CURLE_OK;
+}
+
+static size_t Curl_multissl_version(char *buffer, size_t size);
+
+size_t Curl_ssl_version(char *buffer, size_t size)
+{
+#ifdef CURL_WITH_MULTI_SSL
+  return Curl_multissl_version(buffer, size);
+#else
+  return Curl_ssl->version(buffer, size);
+#endif
+}
+
+/*
+ * This function tries to determine connection status.
+ *
+ * Return codes:
+ *     1 means the connection is still in place
+ *     0 means the connection has been closed
+ *    -1 means the connection status is unknown
+ */
+int Curl_ssl_check_cxn(struct connectdata *conn)
+{
+  return Curl_ssl->check_cxn(conn);
+}
+
+bool Curl_ssl_data_pending(const struct connectdata *conn,
+                           int connindex)
+{
+  return Curl_ssl->data_pending(conn, connindex);
+}
+
+void Curl_ssl_free_certinfo(struct Curl_easy *data)
+{
+  struct curl_certinfo *ci = &data->info.certs;
+
+  if(ci->num_of_certs) {
+    /* free all individual lists used */
+    int i;
+    for(i = 0; i<ci->num_of_certs; i++) {
+      curl_slist_free_all(ci->certinfo[i]);
+      ci->certinfo[i] = NULL;
+    }
+
+    free(ci->certinfo); /* free the actual array too */
+    ci->certinfo = NULL;
+    ci->num_of_certs = 0;
+  }
+}
+
+CURLcode Curl_ssl_init_certinfo(struct Curl_easy *data, int num)
+{
+  struct curl_certinfo *ci = &data->info.certs;
+  struct curl_slist **table;
+
+  /* Free any previous certificate information structures */
+  Curl_ssl_free_certinfo(data);
+
+  /* Allocate the required certificate information structures */
+  table = calloc((size_t) num, sizeof(struct curl_slist *));
+  if(!table)
+    return CURLE_OUT_OF_MEMORY;
+
+  ci->num_of_certs = num;
+  ci->certinfo = table;
+
+  return CURLE_OK;
+}
+
+/*
+ * 'value' is NOT a zero terminated string
+ */
+CURLcode Curl_ssl_push_certinfo_len(struct Curl_easy *data,
+                                    int certnum,
+                                    const char *label,
+                                    const char *value,
+                                    size_t valuelen)
+{
+  struct curl_certinfo *ci = &data->info.certs;
+  char *output;
+  struct curl_slist *nl;
+  CURLcode result = CURLE_OK;
+  size_t labellen = strlen(label);
+  size_t outlen = labellen + 1 + valuelen + 1; /* label:value\0 */
+
+  output = malloc(outlen);
+  if(!output)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* sprintf the label and colon */
+  msnprintf(output, outlen, "%s:", label);
+
+  /* memcpy the value (it might not be zero terminated) */
+  memcpy(&output[labellen + 1], value, valuelen);
+
+  /* zero terminate the output */
+  output[labellen + 1 + valuelen] = 0;
+
+  nl = Curl_slist_append_nodup(ci->certinfo[certnum], output);
+  if(!nl) {
+    free(output);
+    curl_slist_free_all(ci->certinfo[certnum]);
+    result = CURLE_OUT_OF_MEMORY;
+  }
+
+  ci->certinfo[certnum] = nl;
+  return result;
+}
+
+/*
+ * This is a convenience function for push_certinfo_len that takes a zero
+ * terminated value.
+ */
+CURLcode Curl_ssl_push_certinfo(struct Curl_easy *data,
+                                int certnum,
+                                const char *label,
+                                const char *value)
+{
+  size_t valuelen = strlen(value);
+
+  return Curl_ssl_push_certinfo_len(data, certnum, label, value, valuelen);
+}
+
+CURLcode Curl_ssl_random(struct Curl_easy *data,
+                         unsigned char *entropy,
+                         size_t length)
+{
+  return Curl_ssl->random(data, entropy, length);
+}
+
+/*
+ * Public key pem to der conversion
+ */
+
+static CURLcode pubkey_pem_to_der(const char *pem,
+                                  unsigned char **der, size_t *der_len)
+{
+  char *stripped_pem, *begin_pos, *end_pos;
+  size_t pem_count, stripped_pem_count = 0, pem_len;
+  CURLcode result;
+
+  /* if no pem, exit. */
+  if(!pem)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  begin_pos = strstr(pem, "-----BEGIN PUBLIC KEY-----");
+  if(!begin_pos)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  pem_count = begin_pos - pem;
+  /* Invalid if not at beginning AND not directly following \n */
+  if(0 != pem_count && '\n' != pem[pem_count - 1])
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* 26 is length of "-----BEGIN PUBLIC KEY-----" */
+  pem_count += 26;
+
+  /* Invalid if not directly following \n */
+  end_pos = strstr(pem + pem_count, "\n-----END PUBLIC KEY-----");
+  if(!end_pos)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  pem_len = end_pos - pem;
+
+  stripped_pem = malloc(pem_len - pem_count + 1);
+  if(!stripped_pem)
+    return CURLE_OUT_OF_MEMORY;
+
+  /*
+   * Here we loop through the pem array one character at a time between the
+   * correct indices, and place each character that is not '\n' or '\r'
+   * into the stripped_pem array, which should represent the raw base64 string
+   */
+  while(pem_count < pem_len) {
+    if('\n' != pem[pem_count] && '\r' != pem[pem_count])
+      stripped_pem[stripped_pem_count++] = pem[pem_count];
+    ++pem_count;
+  }
+  /* Place the null terminator in the correct place */
+  stripped_pem[stripped_pem_count] = '\0';
+
+  result = Curl_base64_decode(stripped_pem, der, der_len);
+
+  Curl_safefree(stripped_pem);
+
+  return result;
+}
+
+/*
+ * Generic pinned public key check.
+ */
+
+CURLcode Curl_pin_peer_pubkey(struct Curl_easy *data,
+                              const char *pinnedpubkey,
+                              const unsigned char *pubkey, size_t pubkeylen)
+{
+  FILE *fp;
+  unsigned char *buf = NULL, *pem_ptr = NULL;
+  CURLcode result = CURLE_SSL_PINNEDPUBKEYNOTMATCH;
+
+  /* if a path wasn't specified, don't pin */
+  if(!pinnedpubkey)
+    return CURLE_OK;
+  if(!pubkey || !pubkeylen)
+    return result;
+
+  /* only do this if pinnedpubkey starts with "sha256//", length 8 */
+  if(strncmp(pinnedpubkey, "sha256//", 8) == 0) {
+    CURLcode encode;
+    size_t encodedlen, pinkeylen;
+    char *encoded, *pinkeycopy, *begin_pos, *end_pos;
+    unsigned char *sha256sumdigest;
+
+    if(!Curl_ssl->sha256sum) {
+      /* without sha256 support, this cannot match */
+      return result;
+    }
+
+    /* compute sha256sum of public key */
+    sha256sumdigest = malloc(CURL_SHA256_DIGEST_LENGTH);
+    if(!sha256sumdigest)
+      return CURLE_OUT_OF_MEMORY;
+    encode = Curl_ssl->sha256sum(pubkey, pubkeylen,
+                        sha256sumdigest, CURL_SHA256_DIGEST_LENGTH);
+
+    if(encode != CURLE_OK)
+      return encode;
+
+    encode = Curl_base64_encode(data, (char *)sha256sumdigest,
+                                CURL_SHA256_DIGEST_LENGTH, &encoded,
+                                &encodedlen);
+    Curl_safefree(sha256sumdigest);
+
+    if(encode)
+      return encode;
+
+    infof(data, "\t public key hash: sha256//%s\n", encoded);
+
+    /* it starts with sha256//, copy so we can modify it */
+    pinkeylen = strlen(pinnedpubkey) + 1;
+    pinkeycopy = malloc(pinkeylen);
+    if(!pinkeycopy) {
+      Curl_safefree(encoded);
+      return CURLE_OUT_OF_MEMORY;
+    }
+    memcpy(pinkeycopy, pinnedpubkey, pinkeylen);
+    /* point begin_pos to the copy, and start extracting keys */
+    begin_pos = pinkeycopy;
+    do {
+      end_pos = strstr(begin_pos, ";sha256//");
+      /*
+       * if there is an end_pos, null terminate,
+       * otherwise it'll go to the end of the original string
+       */
+      if(end_pos)
+        end_pos[0] = '\0';
+
+      /* compare base64 sha256 digests, 8 is the length of "sha256//" */
+      if(encodedlen == strlen(begin_pos + 8) &&
+         !memcmp(encoded, begin_pos + 8, encodedlen)) {
+        result = CURLE_OK;
+        break;
+      }
+
+      /*
+       * change back the null-terminator we changed earlier,
+       * and look for next begin
+       */
+      if(end_pos) {
+        end_pos[0] = ';';
+        begin_pos = strstr(end_pos, "sha256//");
+      }
+    } while(end_pos && begin_pos);
+    Curl_safefree(encoded);
+    Curl_safefree(pinkeycopy);
+    return result;
+  }
+
+  fp = fopen(pinnedpubkey, "rb");
+  if(!fp)
+    return result;
+
+  do {
+    long filesize;
+    size_t size, pem_len;
+    CURLcode pem_read;
+
+    /* Determine the file's size */
+    if(fseek(fp, 0, SEEK_END))
+      break;
+    filesize = ftell(fp);
+    if(fseek(fp, 0, SEEK_SET))
+      break;
+    if(filesize < 0 || filesize > MAX_PINNED_PUBKEY_SIZE)
+      break;
+
+    /*
+     * if the size of our certificate is bigger than the file
+     * size then it can't match
+     */
+    size = curlx_sotouz((curl_off_t) filesize);
+    if(pubkeylen > size)
+      break;
+
+    /*
+     * Allocate buffer for the pinned key
+     * With 1 additional byte for null terminator in case of PEM key
+     */
+    buf = malloc(size + 1);
+    if(!buf)
+      break;
+
+    /* Returns number of elements read, which should be 1 */
+    if((int) fread(buf, size, 1, fp) != 1)
+      break;
+
+    /* If the sizes are the same, it can't be base64 encoded, must be der */
+    if(pubkeylen == size) {
+      if(!memcmp(pubkey, buf, pubkeylen))
+        result = CURLE_OK;
+      break;
+    }
+
+    /*
+     * Otherwise we will assume it's PEM and try to decode it
+     * after placing null terminator
+     */
+    buf[size] = '\0';
+    pem_read = pubkey_pem_to_der((const char *)buf, &pem_ptr, &pem_len);
+    /* if it wasn't read successfully, exit */
+    if(pem_read)
+      break;
+
+    /*
+     * if the size of our certificate doesn't match the size of
+     * the decoded file, they can't be the same, otherwise compare
+     */
+    if(pubkeylen == pem_len && !memcmp(pubkey, pem_ptr, pubkeylen))
+      result = CURLE_OK;
+  } while(0);
+
+  Curl_safefree(buf);
+  Curl_safefree(pem_ptr);
+  fclose(fp);
+
+  return result;
+}
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+CURLcode Curl_ssl_md5sum(unsigned char *tmp, /* input */
+                         size_t tmplen,
+                         unsigned char *md5sum, /* output */
+                         size_t md5len)
+{
+  return Curl_ssl->md5sum(tmp, tmplen, md5sum, md5len);
+}
+#endif
+
+/*
+ * Check whether the SSL backend supports the status_request extension.
+ */
+bool Curl_ssl_cert_status_request(void)
+{
+  return Curl_ssl->cert_status_request();
+}
+
+/*
+ * Check whether the SSL backend supports false start.
+ */
+bool Curl_ssl_false_start(void)
+{
+  return Curl_ssl->false_start();
+}
+
+/*
+ * Check whether the SSL backend supports setting TLS 1.3 cipher suites
+ */
+bool Curl_ssl_tls13_ciphersuites(void)
+{
+  return Curl_ssl->supports & SSLSUPP_TLS13_CIPHERSUITES;
+}
+
+/*
+ * Default implementations for unsupported functions.
+ */
+
+int Curl_none_init(void)
+{
+  return 1;
+}
+
+void Curl_none_cleanup(void)
+{ }
+
+int Curl_none_shutdown(struct connectdata *conn UNUSED_PARAM,
+                       int sockindex UNUSED_PARAM)
+{
+  (void)conn;
+  (void)sockindex;
+  return 0;
+}
+
+int Curl_none_check_cxn(struct connectdata *conn UNUSED_PARAM)
+{
+  (void)conn;
+  return -1;
+}
+
+CURLcode Curl_none_random(struct Curl_easy *data UNUSED_PARAM,
+                          unsigned char *entropy UNUSED_PARAM,
+                          size_t length UNUSED_PARAM)
+{
+  (void)data;
+  (void)entropy;
+  (void)length;
+  return CURLE_NOT_BUILT_IN;
+}
+
+void Curl_none_close_all(struct Curl_easy *data UNUSED_PARAM)
+{
+  (void)data;
+}
+
+void Curl_none_session_free(void *ptr UNUSED_PARAM)
+{
+  (void)ptr;
+}
+
+bool Curl_none_data_pending(const struct connectdata *conn UNUSED_PARAM,
+                            int connindex UNUSED_PARAM)
+{
+  (void)conn;
+  (void)connindex;
+  return 0;
+}
+
+bool Curl_none_cert_status_request(void)
+{
+  return FALSE;
+}
+
+CURLcode Curl_none_set_engine(struct Curl_easy *data UNUSED_PARAM,
+                              const char *engine UNUSED_PARAM)
+{
+  (void)data;
+  (void)engine;
+  return CURLE_NOT_BUILT_IN;
+}
+
+CURLcode Curl_none_set_engine_default(struct Curl_easy *data UNUSED_PARAM)
+{
+  (void)data;
+  return CURLE_NOT_BUILT_IN;
+}
+
+struct curl_slist *Curl_none_engines_list(struct Curl_easy *data UNUSED_PARAM)
+{
+  (void)data;
+  return (struct curl_slist *)NULL;
+}
+
+bool Curl_none_false_start(void)
+{
+  return FALSE;
+}
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+CURLcode Curl_none_md5sum(unsigned char *input, size_t inputlen,
+                          unsigned char *md5sum, size_t md5len UNUSED_PARAM)
+{
+  MD5_context *MD5pw;
+
+  (void)md5len;
+
+  MD5pw = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!MD5pw)
+    return CURLE_OUT_OF_MEMORY;
+  Curl_MD5_update(MD5pw, input, curlx_uztoui(inputlen));
+  Curl_MD5_final(MD5pw, md5sum);
+  return CURLE_OK;
+}
+#else
+CURLcode Curl_none_md5sum(unsigned char *input UNUSED_PARAM,
+                          size_t inputlen UNUSED_PARAM,
+                          unsigned char *md5sum UNUSED_PARAM,
+                          size_t md5len UNUSED_PARAM)
+{
+  (void)input;
+  (void)inputlen;
+  (void)md5sum;
+  (void)md5len;
+  return CURLE_NOT_BUILT_IN;
+}
+#endif
+
+static int Curl_multissl_init(void)
+{
+  if(multissl_init(NULL))
+    return 1;
+  return Curl_ssl->init();
+}
+
+static CURLcode Curl_multissl_connect(struct connectdata *conn, int sockindex)
+{
+  if(multissl_init(NULL))
+    return CURLE_FAILED_INIT;
+  return Curl_ssl->connect_blocking(conn, sockindex);
+}
+
+static CURLcode Curl_multissl_connect_nonblocking(struct connectdata *conn,
+                                                  int sockindex, bool *done)
+{
+  if(multissl_init(NULL))
+    return CURLE_FAILED_INIT;
+  return Curl_ssl->connect_nonblocking(conn, sockindex, done);
+}
+
+static void *Curl_multissl_get_internals(struct ssl_connect_data *connssl,
+                                         CURLINFO info)
+{
+  if(multissl_init(NULL))
+    return NULL;
+  return Curl_ssl->get_internals(connssl, info);
+}
+
+static void Curl_multissl_close(struct connectdata *conn, int sockindex)
+{
+  if(multissl_init(NULL))
+    return;
+  Curl_ssl->close_one(conn, sockindex);
+}
+
+static const struct Curl_ssl Curl_ssl_multi = {
+  { CURLSSLBACKEND_NONE, "multi" },  /* info */
+  0, /* supports nothing */
+  (size_t)-1, /* something insanely large to be on the safe side */
+
+  Curl_multissl_init,                /* init */
+  Curl_none_cleanup,                 /* cleanup */
+  Curl_multissl_version,             /* version */
+  Curl_none_check_cxn,               /* check_cxn */
+  Curl_none_shutdown,                /* shutdown */
+  Curl_none_data_pending,            /* data_pending */
+  Curl_none_random,                  /* random */
+  Curl_none_cert_status_request,     /* cert_status_request */
+  Curl_multissl_connect,             /* connect */
+  Curl_multissl_connect_nonblocking, /* connect_nonblocking */
+  Curl_multissl_get_internals,       /* get_internals */
+  Curl_multissl_close,               /* close_one */
+  Curl_none_close_all,               /* close_all */
+  Curl_none_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 */
+  NULL                               /* sha256sum */
+};
+
+const struct Curl_ssl *Curl_ssl =
+#if defined(CURL_WITH_MULTI_SSL)
+  &Curl_ssl_multi;
+#elif defined(USE_WOLFSSL)
+  &Curl_ssl_wolfssl;
+#elif defined(USE_SECTRANSP)
+  &Curl_ssl_sectransp;
+#elif defined(USE_GNUTLS)
+  &Curl_ssl_gnutls;
+#elif defined(USE_GSKIT)
+  &Curl_ssl_gskit;
+#elif defined(USE_MBEDTLS)
+  &Curl_ssl_mbedtls;
+#elif defined(USE_NSS)
+  &Curl_ssl_nss;
+#elif defined(USE_OPENSSL)
+  &Curl_ssl_openssl;
+#elif defined(USE_POLARSSL)
+  &Curl_ssl_polarssl;
+#elif defined(USE_SCHANNEL)
+  &Curl_ssl_schannel;
+#elif defined(USE_MESALINK)
+  &Curl_ssl_mesalink;
+#else
+#error "Missing struct Curl_ssl for selected SSL backend"
+#endif
+
+static const struct Curl_ssl *available_backends[] = {
+#if defined(USE_WOLFSSL)
+  &Curl_ssl_wolfssl,
+#endif
+#if defined(USE_SECTRANSP)
+  &Curl_ssl_sectransp,
+#endif
+#if defined(USE_GNUTLS)
+  &Curl_ssl_gnutls,
+#endif
+#if defined(USE_GSKIT)
+  &Curl_ssl_gskit,
+#endif
+#if defined(USE_MBEDTLS)
+  &Curl_ssl_mbedtls,
+#endif
+#if defined(USE_NSS)
+  &Curl_ssl_nss,
+#endif
+#if defined(USE_OPENSSL)
+  &Curl_ssl_openssl,
+#endif
+#if defined(USE_POLARSSL)
+  &Curl_ssl_polarssl,
+#endif
+#if defined(USE_SCHANNEL)
+  &Curl_ssl_schannel,
+#endif
+#if defined(USE_MESALINK)
+  &Curl_ssl_mesalink,
+#endif
+  NULL
+};
+
+static size_t Curl_multissl_version(char *buffer, size_t size)
+{
+  static const struct Curl_ssl *selected;
+  static char backends[200];
+  static size_t total;
+  const struct Curl_ssl *current;
+
+  current = Curl_ssl == &Curl_ssl_multi ? available_backends[0] : Curl_ssl;
+
+  if(current != selected) {
+    char *p = backends;
+    char *end = backends + sizeof(backends);
+    int i;
+
+    selected = current;
+
+    for(i = 0; available_backends[i] && p < (end - 4); i++) {
+      if(i)
+        *(p++) = ' ';
+      if(selected != available_backends[i])
+        *(p++) = '(';
+      p += available_backends[i]->version(p, end - p - 2);
+      if(selected != available_backends[i])
+        *(p++) = ')';
+    }
+    *p = '\0';
+    total = p - backends;
+  }
+
+  if(size > total)
+    memcpy(buffer, backends, total + 1);
+  else {
+    memcpy(buffer, backends, size - 1);
+    buffer[size - 1] = '\0';
+  }
+
+  return CURLMIN(size - 1, total);
+}
+
+static int multissl_init(const struct Curl_ssl *backend)
+{
+  const char *env;
+  char *env_tmp;
+
+  if(Curl_ssl != &Curl_ssl_multi)
+    return 1;
+
+  if(backend) {
+    Curl_ssl = backend;
+    return 0;
+  }
+
+  if(!available_backends[0])
+    return 1;
+
+  env = env_tmp = curl_getenv("CURL_SSL_BACKEND");
+#ifdef CURL_DEFAULT_SSL_BACKEND
+  if(!env)
+    env = CURL_DEFAULT_SSL_BACKEND;
+#endif
+  if(env) {
+    int i;
+    for(i = 0; available_backends[i]; i++) {
+      if(strcasecompare(env, available_backends[i]->info.name)) {
+        Curl_ssl = available_backends[i];
+        curl_free(env_tmp);
+        return 0;
+      }
+    }
+  }
+
+  /* Fall back to first available backend */
+  Curl_ssl = available_backends[0];
+  curl_free(env_tmp);
+  return 0;
+}
+
+CURLsslset curl_global_sslset(curl_sslbackend id, const char *name,
+                              const curl_ssl_backend ***avail)
+{
+  int i;
+
+  if(avail)
+    *avail = (const curl_ssl_backend **)&available_backends;
+
+  if(Curl_ssl != &Curl_ssl_multi)
+    return id == Curl_ssl->info.id ||
+           (name && strcasecompare(name, Curl_ssl->info.name)) ?
+           CURLSSLSET_OK :
+#if defined(CURL_WITH_MULTI_SSL)
+           CURLSSLSET_TOO_LATE;
+#else
+           CURLSSLSET_UNKNOWN_BACKEND;
+#endif
+
+  for(i = 0; available_backends[i]; i++) {
+    if(available_backends[i]->info.id == id ||
+       (name && strcasecompare(available_backends[i]->info.name, name))) {
+      multissl_init(available_backends[i]);
+      return CURLSSLSET_OK;
+    }
+  }
+
+  return CURLSSLSET_UNKNOWN_BACKEND;
+}
+
+#else /* USE_SSL */
+CURLsslset curl_global_sslset(curl_sslbackend id, const char *name,
+                              const curl_ssl_backend ***avail)
+{
+  (void)id;
+  (void)name;
+  (void)avail;
+  return CURLSSLSET_NO_BACKENDS;
+}
+
+#endif /* !USE_SSL */