curl/lib/curl_darwinssl.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 2012, Nick Zitzmann, <nickzman@gmail.com>.
 * Copyright (C) 2012, 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 http://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 iOS and Mac OS X SecureTransport-specific code for the
 * TLS/SSL layer. No code but sslgen.c should ever call or use these functions.
 */

#include "setup.h"

#ifdef USE_DARWINSSL

#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include <Security/Security.h>
#include <Security/SecureTransport.h>
#include <CoreFoundation/CoreFoundation.h>
#include <CommonCrypto/CommonDigest.h>

#include "urldata.h"
#include "sendf.h"
#include "inet_pton.h"
#include "connect.h"
#include "select.h"
#include "sslgen.h"
#include "curl_darwinssl.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"

/* From MacTypes.h (which we can't include because it isn't present in iOS: */
#define ioErr -36

/* The following two functions were ripped from Apple sample code,
 * with some modifications: */
static OSStatus SocketRead(SSLConnectionRef connection,
                           void *data,          /* owned by
                                                 * caller, data
                                                 * RETURNED */
                           size_t *dataLength)  /* IN/OUT */
{
  UInt32 bytesToGo = *dataLength;
  UInt32 initLen = bytesToGo;
  UInt8 *currData = (UInt8 *)data;
  /*int sock = *(int *)connection;*/
  struct ssl_connect_data *connssl = (struct ssl_connect_data *)connection;
  int sock = connssl->ssl_sockfd;
  OSStatus rtn = noErr;
  UInt32 bytesRead;
  int rrtn;
  int theErr;

  *dataLength = 0;

  for(;;) {
    bytesRead = 0;
    rrtn = read(sock, currData, bytesToGo);
    if(rrtn <= 0) {
      /* this is guesswork... */
      theErr = errno;
      if((rrtn == 0) && (theErr == 0)) {
        /* try fix for iSync */
        rtn = errSSLClosedGraceful;
      }
      else /* do the switch */
        switch(theErr) {
          case ENOENT:
            /* connection closed */
            rtn = errSSLClosedGraceful;
            break;
          case ECONNRESET:
            rtn = errSSLClosedAbort;
            break;
          case EAGAIN:
            rtn = errSSLWouldBlock;
            connssl->ssl_direction = false;
            break;
          default:
            rtn = ioErr;
            break;
        }
      break;
    }
    else {
      bytesRead = rrtn;
    }
    bytesToGo -= bytesRead;
    currData  += bytesRead;

    if(bytesToGo == 0) {
      /* filled buffer with incoming data, done */
      break;
    }
  }
  *dataLength = initLen - bytesToGo;

  return rtn;
}

static OSStatus SocketWrite(SSLConnectionRef connection,
                            const void *data,
                            size_t *dataLength)  /* IN/OUT */
{
  UInt32 bytesSent = 0;
  /*int sock = *(int *)connection;*/
  struct ssl_connect_data *connssl = (struct ssl_connect_data *)connection;
  int sock = connssl->ssl_sockfd;
  int length;
  UInt32 dataLen = *dataLength;
  const UInt8 *dataPtr = (UInt8 *)data;
  OSStatus ortn;
  int theErr;

  *dataLength = 0;

  do {
    length = write(sock,
                   (char*)dataPtr + bytesSent,
                   dataLen - bytesSent);
  } while((length > 0) &&
           ( (bytesSent += length) < dataLen) );

  if(length <= 0) {
    theErr = errno;
    if(theErr == EAGAIN) {
      ortn = errSSLWouldBlock;
      connssl->ssl_direction = true;
    }
    else {
      ortn = ioErr;
    }
  }
  else {
    ortn = noErr;
  }
  *dataLength = bytesSent;
  return ortn;
}

CF_INLINE const char *CipherNameForNumber(SSLCipherSuite cipher) {
  switch (cipher) {
    case SSL_RSA_WITH_NULL_MD5:
      return "SSL_RSA_WITH_NULL_MD5";
      break;
    case SSL_RSA_WITH_NULL_SHA:
      return "SSL_RSA_WITH_NULL_SHA";
      break;
    case SSL_RSA_EXPORT_WITH_RC4_40_MD5:
      return "SSL_RSA_EXPORT_WITH_RC4_40_MD5";
      break;
    case SSL_RSA_WITH_RC4_128_MD5:
      return "SSL_RSA_WITH_RC4_128_MD5";
      break;
    case SSL_RSA_WITH_RC4_128_SHA:
      return "SSL_RSA_WITH_RC4_128_SHA";
      break;
    case SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5:
      return "SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5";
      break;
    case SSL_RSA_WITH_IDEA_CBC_SHA:
      return "SSL_RSA_WITH_IDEA_CBC_SHA";
      break;
    case SSL_RSA_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_RSA_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_RSA_WITH_DES_CBC_SHA:
      return "SSL_RSA_WITH_DES_CBC_SHA";
      break;
    case SSL_RSA_WITH_3DES_EDE_CBC_SHA:
      return "SSL_RSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_DH_DSS_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_DH_DSS_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_DH_DSS_WITH_DES_CBC_SHA:
      return "SSL_DH_DSS_WITH_DES_CBC_SHA";
      break;
    case SSL_DH_DSS_WITH_3DES_EDE_CBC_SHA:
      return "SSL_DH_DSS_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_DH_RSA_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_DH_RSA_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_DH_RSA_WITH_DES_CBC_SHA:
      return "SSL_DH_RSA_WITH_DES_CBC_SHA";
      break;
    case SSL_DH_RSA_WITH_3DES_EDE_CBC_SHA:
      return "SSL_DH_RSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_DHE_DSS_WITH_DES_CBC_SHA:
      return "SSL_DHE_DSS_WITH_DES_CBC_SHA";
      break;
    case SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA:
      return "SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_DHE_RSA_WITH_DES_CBC_SHA:
      return "SSL_DHE_RSA_WITH_DES_CBC_SHA";
      break;
    case SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA:
      return "SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_DH_anon_EXPORT_WITH_RC4_40_MD5:
      return "SSL_DH_anon_EXPORT_WITH_RC4_40_MD5";
      break;
    case SSL_DH_anon_WITH_RC4_128_MD5:
      return "SSL_DH_anon_WITH_RC4_128_MD5";
      break;
    case SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA:
      return "SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA";
      break;
    case SSL_DH_anon_WITH_DES_CBC_SHA:
      return "SSL_DH_anon_WITH_DES_CBC_SHA";
      break;
    case SSL_DH_anon_WITH_3DES_EDE_CBC_SHA:
      return "SSL_DH_anon_WITH_3DES_EDE_CBC_SHA";
      break;
    case SSL_FORTEZZA_DMS_WITH_NULL_SHA:
      return "SSL_FORTEZZA_DMS_WITH_NULL_SHA";
      break;
    case SSL_FORTEZZA_DMS_WITH_FORTEZZA_CBC_SHA:
      return "SSL_FORTEZZA_DMS_WITH_FORTEZZA_CBC_SHA";
      break;
    case TLS_RSA_WITH_AES_128_CBC_SHA:
      return "TLS_RSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_DH_DSS_WITH_AES_128_CBC_SHA:
      return "TLS_DH_DSS_WITH_AES_128_CBC_SHA";
      break;
    case TLS_DH_RSA_WITH_AES_128_CBC_SHA:
      return "TLS_DH_RSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_DHE_DSS_WITH_AES_128_CBC_SHA:
      return "TLS_DHE_DSS_WITH_AES_128_CBC_SHA";
      break;
    case TLS_DHE_RSA_WITH_AES_128_CBC_SHA:
      return "TLS_DHE_RSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_DH_anon_WITH_AES_128_CBC_SHA:
      return "TLS_DH_anon_WITH_AES_128_CBC_SHA";
      break;
    case TLS_RSA_WITH_AES_256_CBC_SHA:
      return "TLS_RSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_DH_DSS_WITH_AES_256_CBC_SHA:
      return "TLS_DH_DSS_WITH_AES_256_CBC_SHA";
      break;
    case TLS_DH_RSA_WITH_AES_256_CBC_SHA:
      return "TLS_DH_RSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_DHE_DSS_WITH_AES_256_CBC_SHA:
      return "TLS_DHE_DSS_WITH_AES_256_CBC_SHA";
      break;
    case TLS_DHE_RSA_WITH_AES_256_CBC_SHA:
      return "TLS_DHE_RSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_DH_anon_WITH_AES_256_CBC_SHA:
      return "TLS_DH_anon_WITH_AES_256_CBC_SHA";
      break;
    case TLS_ECDH_ECDSA_WITH_NULL_SHA:
      return "TLS_ECDH_ECDSA_WITH_NULL_SHA";
      break;
    case TLS_ECDH_ECDSA_WITH_RC4_128_SHA:
      return "TLS_ECDH_ECDSA_WITH_RC4_128_SHA";
      break;
    case TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA:
      return "TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA:
      return "TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA:
      return "TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_ECDHE_ECDSA_WITH_NULL_SHA:
      return "TLS_ECDHE_ECDSA_WITH_NULL_SHA";
      break;
    case TLS_ECDHE_ECDSA_WITH_RC4_128_SHA:
      return "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA";
      break;
    case TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA:
      return "TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA:
      return "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:
      return "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_ECDH_RSA_WITH_NULL_SHA:
      return "TLS_ECDH_RSA_WITH_NULL_SHA";
      break;
    case TLS_ECDH_RSA_WITH_RC4_128_SHA:
      return "TLS_ECDH_RSA_WITH_RC4_128_SHA";
      break;
    case TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA:
      return "TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case TLS_ECDH_RSA_WITH_AES_128_CBC_SHA:
      return "TLS_ECDH_RSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_ECDH_RSA_WITH_AES_256_CBC_SHA:
      return "TLS_ECDH_RSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_ECDHE_RSA_WITH_NULL_SHA:
      return "TLS_ECDHE_RSA_WITH_NULL_SHA";
      break;
    case TLS_ECDHE_RSA_WITH_RC4_128_SHA:
      return "TLS_ECDHE_RSA_WITH_RC4_128_SHA";
      break;
    case TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA:
      return "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA";
      break;
    case TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:
      return "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA";
      break;
    case TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
      return "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA";
      break;
    case TLS_ECDH_anon_WITH_NULL_SHA:
      return "TLS_ECDH_anon_WITH_NULL_SHA";
      break;
    case TLS_ECDH_anon_WITH_RC4_128_SHA:
      return "TLS_ECDH_anon_WITH_RC4_128_SHA";
      break;
    case TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA:
      return "TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA";
      break;
    case TLS_ECDH_anon_WITH_AES_128_CBC_SHA:
      return "TLS_ECDH_anon_WITH_AES_128_CBC_SHA";
      break;
    case TLS_ECDH_anon_WITH_AES_256_CBC_SHA:
      return "TLS_ECDH_anon_WITH_AES_256_CBC_SHA";
      break;
    case SSL_RSA_WITH_RC2_CBC_MD5:
      return "SSL_RSA_WITH_RC2_CBC_MD5";
      break;
    case SSL_RSA_WITH_IDEA_CBC_MD5:
      return "SSL_RSA_WITH_IDEA_CBC_MD5";
      break;
    case SSL_RSA_WITH_DES_CBC_MD5:
      return "SSL_RSA_WITH_DES_CBC_MD5";
      break;
    case SSL_RSA_WITH_3DES_EDE_CBC_MD5:
      return "SSL_RSA_WITH_3DES_EDE_CBC_MD5";
      break;
  }
  return "(NONE)";
}

static CURLcode darwinssl_connect_step1(struct connectdata *conn,
                                        int sockindex)
{
  struct SessionHandle *data = conn->data;
  curl_socket_t sockfd = conn->sock[sockindex];
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  bool sni = true;
#ifdef ENABLE_IPV6
  struct in6_addr addr;
#else
  struct in_addr addr;
#endif
  /*SSLConnectionRef ssl_connection;*/
  OSStatus err = noErr;

  if(connssl->ssl_ctx)
    (void)SSLDisposeContext(connssl->ssl_ctx);
  err = SSLNewContext(false, &(connssl->ssl_ctx));
  if(err != noErr) {
    failf(data, "SSL: couldn't create a context: OSStatus %d", err);
    return CURLE_OUT_OF_MEMORY;
  }

  /* check to see if we've been told to use an explicit SSL/TLS version */
  (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx, kSSLProtocolAll, false);
  switch(data->set.ssl.version) {
    default:
    case CURL_SSLVERSION_DEFAULT:
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kSSLProtocol3,
                                         true);
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kTLSProtocol1,
                                         true);
      break;
    case CURL_SSLVERSION_TLSv1:
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kTLSProtocol1,
                                         true);
      break;
    case CURL_SSLVERSION_SSLv2:
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kSSLProtocol2,
                                         true);
      break;
    case CURL_SSLVERSION_SSLv3:
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kSSLProtocol3,
                                         true);
      break;
  }

  /* No need to load certificates here. SecureTransport uses the Keychain
   * (which is also part of the Security framework) to evaluate trust. */

  /* 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. */
  err = SSLSetEnableCertVerify(connssl->ssl_ctx,
                               data->set.ssl.verifypeer?true:false);
  if(err != noErr) {
    failf(data, "SSL: SSLSetEnableCertVerify() failed: OSStatus %d", err);
    return CURLE_SSL_CONNECT_ERROR;
  }

  /* If this is a domain name and not an IP address, then configure SNI: */
  if((0 == Curl_inet_pton(AF_INET, conn->host.name, &addr)) &&
#ifdef ENABLE_IPV6
     (0 == Curl_inet_pton(AF_INET6, conn->host.name, &addr)) &&
#endif
     sni) {
    err = SSLSetPeerDomainName(connssl->ssl_ctx, conn->host.name,
                               strlen(conn->host.name));
    if(err != noErr) {
      infof(data, "WARNING: SSL: SSLSetPeerDomainName() failed: OSStatus %d",
            err);
    }
  }

  err = SSLSetIOFuncs(connssl->ssl_ctx, SocketRead, SocketWrite);
  if(err != noErr) {
    failf(data, "SSL: SSLSetIOFuncs() failed: OSStatus %d", err);
    return CURLE_SSL_CONNECT_ERROR;
  }

  /* pass the raw socket into the SSL layers */
  /* We need to store the FD in a constant memory address, because
   * SSLSetConnection() will not copy that address. I've found that
   * conn->sock[sockindex] may change on its own. */
  connssl->ssl_sockfd = sockfd;
  /*ssl_connection = &(connssl->ssl_sockfd);
  err = SSLSetConnection(connssl->ssl_ctx, ssl_connection);*/
  err = SSLSetConnection(connssl->ssl_ctx, connssl);
  if(err != noErr) {
    failf(data, "SSL: SSLSetConnection() failed: %d", err);
    return CURLE_SSL_CONNECT_ERROR;
  }

  connssl->connecting_state = ssl_connect_2;
  return CURLE_OK;
}

static CURLcode
darwinssl_connect_step2(struct connectdata *conn, int sockindex)
{
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  OSStatus err;
  SSLCipherSuite cipher;

  DEBUGASSERT(ssl_connect_2 == connssl->connecting_state
              || ssl_connect_2_reading == connssl->connecting_state
              || ssl_connect_2_writing == connssl->connecting_state);

  /* Here goes nothing: */
  err = SSLHandshake(connssl->ssl_ctx);

  if(err != noErr) {
    switch (err) {
      case errSSLWouldBlock:  /* they're not done with us yet */
        connssl->connecting_state = connssl->ssl_direction ?
            ssl_connect_2_writing : ssl_connect_2_reading;
        return CURLE_OK;
        break;

      case errSSLServerAuthCompleted:
        /* the documentation says we need to call SSLHandshake() again */
        return darwinssl_connect_step2(conn, sockindex);

      case errSSLXCertChainInvalid:
      case errSSLUnknownRootCert:
      case errSSLNoRootCert:
      case errSSLCertExpired:
        failf(data, "SSL certificate problem: OSStatus %d", err);
        return CURLE_SSL_CACERT;
        break;

      default:
        failf(data, "Unknown SSL protocol error in connection to %s:%d",
              conn->host.name, err);
        return CURLE_SSL_CONNECT_ERROR;
        break;
    }
  }
  else {
    /* we have been connected fine, we're not waiting for anything else. */
    connssl->connecting_state = ssl_connect_3;

    /* Informational message */
    (void)SSLGetNegotiatedCipher(connssl->ssl_ctx, &cipher);
    infof (data, "SSL connection using %s\n", CipherNameForNumber(cipher));

    return CURLE_OK;
  }
}

static CURLcode
darwinssl_connect_step3(struct connectdata *conn,
                        int sockindex)
{
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  CFStringRef server_cert_summary;
  char server_cert_summary_c[128];
  CFArrayRef server_certs;
  SecCertificateRef server_cert;
  OSStatus err;
  CFIndex i, count;

  /* There is no step 3!
   * Well, okay, if verbose mode is on, let's print the details of the
   * server certificates. */
  err = SSLCopyPeerCertificates(connssl->ssl_ctx, &server_certs);
  if(err == noErr) {
    count = CFArrayGetCount(server_certs);
    for(i = 0L ; i < count ; i++) {
      server_cert = (SecCertificateRef)CFArrayGetValueAtIndex(server_certs, i);

      server_cert_summary = SecCertificateCopySubjectSummary(server_cert);
      memset(server_cert_summary_c, 0, 128);
      if(CFStringGetCString(server_cert_summary,
                            server_cert_summary_c,
                            128,
                            kCFStringEncodingUTF8)) {
        infof(data, "Server certificate: %s\n", server_cert_summary_c);
      }
      CFRelease(server_cert_summary);
    }
    CFRelease(server_certs);
  }

  connssl->connecting_state = ssl_connect_done;
  return CURLE_OK;
}

static Curl_recv darwinssl_recv;
static Curl_send darwinssl_send;

static CURLcode
darwinssl_connect_common(struct connectdata *conn,
                         int sockindex,
                         bool nonblocking,
                         bool *done)
{
  CURLcode retcode;
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  curl_socket_t sockfd = conn->sock[sockindex];
  long 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 = darwinssl_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_ready(readfd, 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 done nonblocking 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 = darwinssl_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 = darwinssl_connect_step3(conn, sockindex);
    if(retcode)
      return retcode;
  }

  if(ssl_connect_done==connssl->connecting_state) {
    connssl->state = ssl_connection_complete;
    conn->recv[sockindex] = darwinssl_recv;
    conn->send[sockindex] = darwinssl_send;
    *done = TRUE;
  }
  else
    *done = FALSE;

  /* Reset our connect state machine */
  connssl->connecting_state = ssl_connect_1;

  return CURLE_OK;
}

CURLcode
Curl_darwinssl_connect_nonblocking(struct connectdata *conn,
                                   int sockindex,
                                   bool *done)
{
  return darwinssl_connect_common(conn, sockindex, TRUE, done);
}

CURLcode
Curl_darwinssl_connect(struct connectdata *conn,
                       int sockindex)
{
  CURLcode retcode;
  bool done = FALSE;

  retcode = darwinssl_connect_common(conn, sockindex, FALSE, &done);

  if(retcode)
    return retcode;

  DEBUGASSERT(done);

  return CURLE_OK;
}

void Curl_darwinssl_close(struct connectdata *conn, int sockindex)
{
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];

  (void)SSLClose(connssl->ssl_ctx);
  (void)SSLDisposeContext(connssl->ssl_ctx);
  connssl->ssl_ctx = NULL;
  connssl->ssl_sockfd = 0;
}

void Curl_darwinssl_close_all(struct SessionHandle *data)
{
  /* SecureTransport doesn't separate sessions from contexts, so... */
  (void)data;
}

int Curl_darwinssl_shutdown(struct connectdata *conn, int sockindex)
{
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  struct SessionHandle *data = conn->data;
  ssize_t nread;
  int what;
  int rc;
  char buf[120];

  if(!connssl->ssl_ctx)
    return 0;

  if(data->set.ftp_ccc != CURLFTPSSL_CCC_ACTIVE)
    return 0;

  Curl_darwinssl_close(conn, sockindex);

  rc = 0;

  what = Curl_socket_ready(conn->sock[sockindex],
                           CURL_SOCKET_BAD, SSL_SHUTDOWN_TIMEOUT);

  for(;;) {
    if(what < 0) {
      /* anything that gets here is fatally bad */
      failf(data, "select/poll on SSL socket, errno: %d", SOCKERRNO);
      rc = -1;
      break;
    }

    if(!what) {                                /* timeout */
      failf(data, "SSL shutdown timeout");
      break;
    }

    /* Something to read, let's do it and hope that it is the close
     notify alert from the server. No way to SSL_Read now, so use read(). */

    nread = read(conn->sock[sockindex], buf, sizeof(buf));

    if(nread < 0) {
      failf(data, "read: %s", strerror(errno));
      rc = -1;
    }

    if(nread <= 0)
      break;

    what = Curl_socket_ready(conn->sock[sockindex], CURL_SOCKET_BAD, 0);
  }

  return rc;
}

size_t Curl_darwinssl_version(char *buffer, size_t size)
{
  return snprintf(buffer, size, "SecureTransport");
}

/*
 * This function uses SSLGetSessionState 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_darwinssl_check_cxn(struct connectdata *conn)
{
  struct ssl_connect_data *connssl = &conn->ssl[FIRSTSOCKET];
  OSStatus err;
  SSLSessionState state;

  if(connssl->ssl_ctx) {
    err = SSLGetSessionState(connssl->ssl_ctx, &state);
    if(err == noErr)
      return state == kSSLConnected || state == kSSLHandshake;
    return -1;
  }
  return 0;
}

bool Curl_darwinssl_data_pending(const struct connectdata *conn,
                                 int connindex)
{
  const struct ssl_connect_data *connssl = &conn->ssl[connindex];
  OSStatus err;
  size_t buffer;

  if(connssl->ssl_ctx) {  /* SSL is in use */
    err = SSLGetBufferedReadSize(connssl->ssl_ctx, &buffer);
    if(err == noErr)
      return buffer > 0UL;
    return false;
  }
  else
    return false;
}

void Curl_darwinssl_random(struct SessionHandle *data,
                           unsigned char *entropy,
                           size_t length)
{
  /* arc4random_buf() isn't available on cats older than Lion, so let's
     do this manually for the benefit of the older cats. */
  size_t i;
  u_int32_t random = 0;

  for(i = 0 ; i < length ; i++) {
    if(i % sizeof(u_int32_t) == 0)
      random = arc4random();
    entropy[i] = random & 0xFF;
    random >>= 8;
  }
  i = random = 0;
  (void)data;
}

void Curl_darwinssl_md5sum(unsigned char *tmp, /* input */
                           size_t tmplen,
                           unsigned char *md5sum, /* output */
                           size_t md5len)
{
  (void)md5len;
  (void)CC_MD5(tmp, tmplen, md5sum);
}

static ssize_t darwinssl_send(struct connectdata *conn,
                              int sockindex,
                              const void *mem,
                              size_t len,
                              CURLcode *curlcode)
{
  /*struct SessionHandle *data = conn->data;*/
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  size_t processed;
  OSStatus err = SSLWrite(connssl->ssl_ctx, mem, len, &processed);

  if(err != noErr) {
    switch (err) {
      case errSSLWouldBlock:  /* we're not done yet; keep sending */
        *curlcode = CURLE_AGAIN;
        return -1;
        break;

      default:
        failf(conn->data, "SSLWrite() return error %d", err);
        *curlcode = CURLE_SEND_ERROR;
        return -1;
        break;
    }
  }
  return (ssize_t)processed;
}

static ssize_t darwinssl_recv(struct connectdata *conn,
                              int num,
                              char *buf,
                              size_t buffersize,
                              CURLcode *curlcode)
{
  /*struct SessionHandle *data = conn->data;*/
  struct ssl_connect_data *connssl = &conn->ssl[num];
  size_t processed;
  OSStatus err = SSLRead(connssl->ssl_ctx, buf, buffersize, &processed);

  if(err != noErr) {
    switch (err) {
      case errSSLWouldBlock:  /* we're not done yet; keep reading */
        *curlcode = CURLE_AGAIN;
        return -1;
        break;

      default:
        failf(conn->data, "SSLRead() return error %d", err);
        *curlcode = CURLE_RECV_ERROR;
        return -1;
        break;
    }
  }
  return (ssize_t)processed;
}

#endif /* USE_DARWINSSL */