curl_darwinssl.c

        err = SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                           kSSLProtocol2,
                                           true);
        if(err != noErr) {
          failf(data, "Your version of the OS does not support SSLv2");
          return CURLE_SSL_CONNECT_ERROR;
        }
        break;
    }
#endif  /* CURL_SUPPORT_MAC_10_8 */
  }
#else
  (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:
      err = SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kSSLProtocol2,
                                         true);
      if(err != noErr) {
        failf(data, "Your version of the OS does not support SSLv2");
        return CURLE_SSL_CONNECT_ERROR;
      }
      break;
    case CURL_SSLVERSION_SSLv3:
      (void)SSLSetProtocolVersionEnabled(connssl->ssl_ctx,
                                         kSSLProtocol3,
                                         true);
      break;
  }
#endif /* CURL_BUILD_MAC_10_8 || CURL_BUILD_IOS */

  if(data->set.str[STRING_KEY]) {
    infof(data, "WARNING: SSL: CURLOPT_SSLKEY is ignored by Secure "
                "Transport. The private key must be in the Keychain.\n");
  }

  if(data->set.str[STRING_CERT]) {
    SecIdentityRef cert_and_key = NULL;
    bool is_cert_file = is_file(data->set.str[STRING_CERT]);

    /* User wants to authenticate with a client cert. Look for it:
       If we detect that this is a file on disk, then let's load it.
       Otherwise, assume that the user wants to use an identity loaded
       from the Keychain. */
    if(is_cert_file) {
      if(!data->set.str[STRING_CERT_TYPE])
        infof(data, "WARNING: SSL: Certificate type not set, assuming "
                    "PKCS#12 format.\n");
      else if(strncmp(data->set.str[STRING_CERT_TYPE], "P12",
        strlen(data->set.str[STRING_CERT_TYPE])) != 0)
        infof(data, "WARNING: SSL: The Security framework only supports "
                    "loading identities that are in PKCS#12 format.\n");

      err = CopyIdentityFromPKCS12File(data->set.str[STRING_CERT],
        data->set.str[STRING_KEY_PASSWD], &cert_and_key);
    }
    else
      err = CopyIdentityWithLabel(data->set.str[STRING_CERT], &cert_and_key);

    if(err == noErr) {
      SecCertificateRef cert = NULL;
      CFTypeRef certs_c[1];
      CFArrayRef certs;

      /* If we found one, print it out: */
      err = SecIdentityCopyCertificate(cert_and_key, &cert);
      if(err == noErr) {
        CFStringRef cert_summary = CopyCertSubject(cert);
        char cert_summary_c[128];

        if(cert_summary) {
          memset(cert_summary_c, 0, 128);
          if(CFStringGetCString(cert_summary,
                                cert_summary_c,
                                128,
                                kCFStringEncodingUTF8)) {
            infof(data, "Client certificate: %s\n", cert_summary_c);
          }
          CFRelease(cert_summary);
          CFRelease(cert);
        }
      }
      certs_c[0] = cert_and_key;
      certs = CFArrayCreate(NULL, (const void **)certs_c, 1L,
                            &kCFTypeArrayCallBacks);
      err = SSLSetCertificate(connssl->ssl_ctx, certs);
      if(certs)
        CFRelease(certs);
      if(err != noErr) {
        failf(data, "SSL: SSLSetCertificate() failed: OSStatus %d", err);
        return CURLE_SSL_CERTPROBLEM;
      }
      CFRelease(cert_and_key);
    }
    else {
      switch(err) {
        case errSecPkcs12VerifyFailure: case errSecAuthFailed:
          failf(data, "SSL: Incorrect password for the certificate \"%s\" "
                      "and its private key.", data->set.str[STRING_CERT]);
          break;
        case errSecDecode: case errSecUnknownFormat:
          failf(data, "SSL: Couldn't make sense of the data in the "
                      "certificate \"%s\" and its private key.",
                      data->set.str[STRING_CERT]);
          break;
        case errSecPassphraseRequired:
          failf(data, "SSL The certificate \"%s\" requires a password.",
                      data->set.str[STRING_CERT]);
          break;
        case errSecItemNotFound:
          failf(data, "SSL: Can't find the certificate \"%s\" and its private "
                      "key in the Keychain.", data->set.str[STRING_CERT]);
          break;
        default:
          failf(data, "SSL: Can't load the certificate \"%s\" and its private "
                      "key: OSStatus %d", data->set.str[STRING_CERT], err);
          break;
      }
      return CURLE_SSL_CERTPROBLEM;
    }
  }

  /* 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. */
#if CURL_BUILD_MAC_10_6 || CURL_BUILD_IOS
  /* Snow Leopard introduced the SSLSetSessionOption() function, but due to
     a library bug with the way the kSSLSessionOptionBreakOnServerAuth flag
     works, it doesn't work as expected under Snow Leopard or Lion.
     So we need to call SSLSetEnableCertVerify() on those older cats in order
     to disable certificate validation if the user turned that off.
     (SecureTransport will always validate the certificate chain by
     default.) */
  /* (Note: Darwin 12.x.x is Mountain Lion.) */
#if CURL_BUILD_MAC
  if(SSLSetSessionOption != NULL && darwinver_maj >= 12) {
#else
  if(SSLSetSessionOption != NULL) {
#endif /* CURL_BUILD_MAC */
    err = SSLSetSessionOption(connssl->ssl_ctx,
                              kSSLSessionOptionBreakOnServerAuth,
                              data->set.ssl.verifypeer?false:true);
    if(err != noErr) {
      failf(data, "SSL: SSLSetSessionOption() failed: OSStatus %d", err);
      return CURLE_SSL_CONNECT_ERROR;
    }
  }
  else {
#if CURL_SUPPORT_MAC_10_8
    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;
    }
#endif /* CURL_SUPPORT_MAC_10_8 */
  }
#else
  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;
  }
#endif /* CURL_BUILD_MAC_10_6 || CURL_BUILD_IOS */

  /* If this is a domain name and not an IP address, then configure SNI.
   * Also: the verifyhost setting influences SNI usage */
  /* 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
     data->set.ssl.verifyhost) {
    err = SSLSetPeerDomainName(connssl->ssl_ctx, conn->host.name,
                               strlen(conn->host.name));
    if(err != noErr) {
      infof(data, "WARNING: SSL: SSLSetPeerDomainName() failed: OSStatus %d\n",
            err);
    }
  }

  /* Disable cipher suites that ST supports but are not safe. These ciphers
     are unlikely to be used in any case since ST gives other ciphers a much
     higher priority, but it's probably better that we not connect at all than
     to give the user a false sense of security if the server only supports
     insecure ciphers. (Note: We don't care about SSLv2-only ciphers.) */
  (void)SSLGetNumberSupportedCiphers(connssl->ssl_ctx, &all_ciphers_count);
  all_ciphers = malloc(all_ciphers_count*sizeof(SSLCipherSuite));
  allowed_ciphers = malloc(all_ciphers_count*sizeof(SSLCipherSuite));
  if(all_ciphers && allowed_ciphers &&
     SSLGetSupportedCiphers(connssl->ssl_ctx, all_ciphers,
       &all_ciphers_count) == noErr) {
    for(i = 0UL ; i < all_ciphers_count ; i++) {
#if CURL_BUILD_MAC
     /* There's a known bug in early versions of Mountain Lion where ST's ECC
        ciphers (cipher suite 0xC001 through 0xC032) simply do not work.
        Work around the problem here by disabling those ciphers if we are
        running in an affected version of OS X. */
      if(darwinver_maj == 12 && darwinver_min <= 3 &&
         all_ciphers[i] >= 0xC001 && all_ciphers[i] <= 0xC032) {
           continue;
      }
#endif /* CURL_BUILD_MAC */
      switch(all_ciphers[i]) {
        /* Disable NULL ciphersuites: */
        case SSL_NULL_WITH_NULL_NULL:
        case SSL_RSA_WITH_NULL_MD5:
        case SSL_RSA_WITH_NULL_SHA:
        case SSL_FORTEZZA_DMS_WITH_NULL_SHA:
        case 0xC001: /* TLS_ECDH_ECDSA_WITH_NULL_SHA */
        case 0xC006: /* TLS_ECDHE_ECDSA_WITH_NULL_SHA */
        case 0xC00B: /* TLS_ECDH_RSA_WITH_NULL_SHA */
        case 0xC010: /* TLS_ECDHE_RSA_WITH_NULL_SHA */
        /* Disable anonymous ciphersuites: */
        case SSL_DH_anon_EXPORT_WITH_RC4_40_MD5:
        case SSL_DH_anon_WITH_RC4_128_MD5:
        case SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_DH_anon_WITH_DES_CBC_SHA:
        case SSL_DH_anon_WITH_3DES_EDE_CBC_SHA:
        case TLS_DH_anon_WITH_AES_128_CBC_SHA:
        case TLS_DH_anon_WITH_AES_256_CBC_SHA:
        case 0xC015: /* TLS_ECDH_anon_WITH_NULL_SHA */
        case 0xC016: /* TLS_ECDH_anon_WITH_RC4_128_SHA */
        case 0xC017: /* TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA */
        case 0xC018: /* TLS_ECDH_anon_WITH_AES_128_CBC_SHA */
        case 0xC019: /* TLS_ECDH_anon_WITH_AES_256_CBC_SHA */
        case 0x006C: /* TLS_DH_anon_WITH_AES_128_CBC_SHA256 */
        case 0x006D: /* TLS_DH_anon_WITH_AES_256_CBC_SHA256 */
        case 0x00A6: /* TLS_DH_anon_WITH_AES_128_GCM_SHA256 */
        case 0x00A7: /* TLS_DH_anon_WITH_AES_256_GCM_SHA384 */
        /* Disable weak key ciphersuites: */
        case SSL_RSA_EXPORT_WITH_RC4_40_MD5:
        case SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5:
        case SSL_RSA_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_DH_DSS_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_DH_RSA_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA:
        case SSL_RSA_WITH_DES_CBC_SHA:
        case SSL_DH_DSS_WITH_DES_CBC_SHA:
        case SSL_DH_RSA_WITH_DES_CBC_SHA:
        case SSL_DHE_DSS_WITH_DES_CBC_SHA:
        case SSL_DHE_RSA_WITH_DES_CBC_SHA:
        /* Disable IDEA: */
        case SSL_RSA_WITH_IDEA_CBC_SHA:
        case SSL_RSA_WITH_IDEA_CBC_MD5:
          break;
        default: /* enable everything else */
          allowed_ciphers[allowed_ciphers_count++] = all_ciphers[i];
          break;
      }
    }
    err = SSLSetEnabledCiphers(connssl->ssl_ctx, allowed_ciphers,
                               allowed_ciphers_count);
    if(err != noErr) {
      failf(data, "SSL: SSLSetEnabledCiphers() failed: OSStatus %d", err);
      return CURLE_SSL_CONNECT_ERROR;
    }
  }
  else {
    Curl_safefree(all_ciphers);
    Curl_safefree(allowed_ciphers);
    failf(data, "SSL: Failed to allocate memory for allowed ciphers");
    return CURLE_OUT_OF_MEMORY;
  }
  Curl_safefree(all_ciphers);
  Curl_safefree(allowed_ciphers);

  /* Check if there's a cached ID we can/should use here! */
  if(!Curl_ssl_getsessionid(conn, (void **)&ssl_sessionid,
    &ssl_sessionid_len)) {
    /* we got a session id, use it! */
    err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
    if(err != noErr) {
      failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
      return CURLE_SSL_CONNECT_ERROR;
    }
    /* Informational message */
    infof(data, "SSL re-using session ID\n");
  }
  /* If there isn't one, then let's make one up! This has to be done prior
     to starting the handshake. */
  else {
    CURLcode retcode;

    ssl_sessionid = malloc(256*sizeof(char));
    ssl_sessionid_len = snprintf(ssl_sessionid, 256, "curl:%s:%hu",
      conn->host.name, conn->remote_port);
    err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
    if(err != noErr) {
      failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
      return CURLE_SSL_CONNECT_ERROR;
    }
    retcode = Curl_ssl_addsessionid(conn, ssl_sessionid, ssl_sessionid_len);
    if(retcode!= CURLE_OK) {
      failf(data, "failed to store ssl session");
      return retcode;
    }
  }

  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;
  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;
  SSLProtocol protocol = 0;

  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;

      /* The below is errSSLServerAuthCompleted; it's not defined in
        Leopard's headers */
      case -9841:
        /* the documentation says we need to call SSLHandshake() again */
        return darwinssl_connect_step2(conn, sockindex);

      /* These are all certificate problems with the server: */
      case errSSLXCertChainInvalid:
        failf(data, "SSL certificate problem: Invalid certificate chain");
        return CURLE_SSL_CACERT;
      case errSSLUnknownRootCert:
        failf(data, "SSL certificate problem: Untrusted root certificate");
        return CURLE_SSL_CACERT;
      case errSSLNoRootCert:
        failf(data, "SSL certificate problem: No root certificate");
        return CURLE_SSL_CACERT;
      case errSSLCertExpired:
        failf(data, "SSL certificate problem: Certificate chain had an "
              "expired certificate");
        return CURLE_SSL_CACERT;
      case errSSLBadCert:
        failf(data, "SSL certificate problem: Couldn't understand the server "
              "certificate format");
        return CURLE_SSL_CONNECT_ERROR;

      /* These are all certificate problems with the client: */
      case errSecAuthFailed:
        failf(data, "SSL authentication failed");
        return CURLE_SSL_CONNECT_ERROR;
      case errSSLPeerHandshakeFail:
        failf(data, "SSL peer handshake failed, the server most likely "
              "requires a client certificate to connect");
        return CURLE_SSL_CONNECT_ERROR;
      case errSSLPeerUnknownCA:
        failf(data, "SSL server rejected the client certificate due to "
              "the certificate being signed by an unknown certificate "
              "authority");
        return CURLE_SSL_CONNECT_ERROR;

      /* This error is raised if the server's cert didn't match the server's
         host name: */
      case errSSLHostNameMismatch:
        failf(data, "SSL certificate peer verification failed, the "
              "certificate did not match \"%s\"\n", conn->host.dispname);
        return CURLE_PEER_FAILED_VERIFICATION;

      /* Generic handshake errors: */
      case errSSLConnectionRefused:
        failf(data, "Server dropped the connection during the SSL handshake");
        return CURLE_SSL_CONNECT_ERROR;
      case errSSLClosedAbort:
        failf(data, "Server aborted the SSL handshake");
        return CURLE_SSL_CONNECT_ERROR;
      case errSSLNegotiation:
        failf(data, "Could not negotiate an SSL cipher suite with the server");
        return CURLE_SSL_CONNECT_ERROR;
      /* Sometimes paramErr happens with buggy ciphers: */
      case paramErr: case errSSLInternal:
        failf(data, "Internal SSL engine error encountered during the "
              "SSL handshake");
        return CURLE_SSL_CONNECT_ERROR;
      case errSSLFatalAlert:
        failf(data, "Fatal SSL engine error encountered during the SSL "
              "handshake");
        return CURLE_SSL_CONNECT_ERROR;
      default:
        failf(data, "Unknown SSL protocol error in connection to %s:%d",
              conn->host.name, err);
        return CURLE_SSL_CONNECT_ERROR;
    }
  }
  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);
    (void)SSLGetNegotiatedProtocolVersion(connssl->ssl_ctx, &protocol);
    switch (protocol) {
      case kSSLProtocol2:
        infof(data, "SSL 2.0 connection using %s\n",
              SSLCipherNameForNumber(cipher));
        break;
      case kSSLProtocol3:
        infof(data, "SSL 3.0 connection using %s\n",
              SSLCipherNameForNumber(cipher));
        break;
      case kTLSProtocol1:
        infof(data, "TLS 1.0 connection using %s\n",
              TLSCipherNameForNumber(cipher));
        break;
#if CURL_BUILD_MAC_10_8 || CURL_BUILD_IOS
      case kTLSProtocol11:
        infof(data, "TLS 1.1 connection using %s\n",
              TLSCipherNameForNumber(cipher));
        break;
      case kTLSProtocol12:
        infof(data, "TLS 1.2 connection using %s\n",
              TLSCipherNameForNumber(cipher));
        break;
#endif
      default:
        infof(data, "Unknown protocol connection\n");
        break;
    }

    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 = NULL;
  SecCertificateRef server_cert;
  OSStatus err;
  CFIndex i, count;
  SecTrustRef trust = NULL;

  /* There is no step 3!
   * Well, okay, if verbose mode is on, let's print the details of the
   * server certificates. */
#if CURL_BUILD_MAC_10_7 || CURL_BUILD_IOS
#if CURL_BUILD_IOS
#pragma unused(server_certs)
  err = SSLCopyPeerTrust(connssl->ssl_ctx, &trust);
  /* For some reason, SSLCopyPeerTrust() can return noErr and yet return
     a null trust, so be on guard for that: */
  if(err == noErr && trust) {
    count = SecTrustGetCertificateCount(trust);
    for(i = 0L ; i < count ; i++) {
      server_cert = SecTrustGetCertificateAtIndex(trust, i);
      server_cert_summary = CopyCertSubject(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(trust);
  }
#else
  /* SSLCopyPeerCertificates() is deprecated as of Mountain Lion.
     The function SecTrustGetCertificateAtIndex() is officially present
     in Lion, but it is unfortunately also present in Snow Leopard as
     private API and doesn't work as expected. So we have to look for
     a different symbol to make sure this code is only executed under
     Lion or later. */
  if(SecTrustEvaluateAsync != NULL) {
#pragma unused(server_certs)
    err = SSLCopyPeerTrust(connssl->ssl_ctx, &trust);
    /* For some reason, SSLCopyPeerTrust() can return noErr and yet return
       a null trust, so be on guard for that: */
    if(err == noErr && trust) {
      count = SecTrustGetCertificateCount(trust);
      for(i = 0L ; i < count ; i++) {
        server_cert = SecTrustGetCertificateAtIndex(trust, i);
        server_cert_summary = CopyCertSubject(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(trust);
    }
  }
  else {
#if CURL_SUPPORT_MAC_10_8
    err = SSLCopyPeerCertificates(connssl->ssl_ctx, &server_certs);
    /* Just in case SSLCopyPeerCertificates() returns null too... */
    if(err == noErr && server_certs) {
      count = CFArrayGetCount(server_certs);
      for(i = 0L ; i < count ; i++) {
        server_cert = (SecCertificateRef)CFArrayGetValueAtIndex(server_certs,
                                                                i);

        server_cert_summary = CopyCertSubject(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);
    }
#endif /* CURL_SUPPORT_MAC_10_8 */
  }
#endif /* CURL_BUILD_IOS */
#else
#pragma unused(trust)
  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 = CopyCertSubject(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);
  }
#endif /* CURL_BUILD_MAC_10_7 || CURL_BUILD_IOS */

  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];

  if(connssl->ssl_ctx) {
    (void)SSLClose(connssl->ssl_ctx);
#if CURL_BUILD_MAC_10_8 || CURL_BUILD_IOS
    if(SSLCreateContext != NULL)
      CFRelease(connssl->ssl_ctx);
#if CURL_SUPPORT_MAC_10_8
    else
      (void)SSLDisposeContext(connssl->ssl_ctx);
#endif  /* CURL_SUPPORT_MAC_10_8 */
#else
    (void)SSLDisposeContext(connssl->ssl_ctx);
#endif /* CURL_BUILD_MAC_10_8 || CURL_BUILD_IOS */
    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;
}

void Curl_darwinssl_session_free(void *ptr)
{
  /* ST, as of iOS 5 and Mountain Lion, has no public method of deleting a
     cached session ID inside the Security framework. There is a private
     function that does this, but I don't want to have to explain to you why I
     got your application rejected from the App Store due to the use of a
     private API, so the best we can do is free up our own char array that we
     created way back in darwinssl_connect_step1... */
  Curl_safefree(ptr);
}

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_number = 0;

  for(i = 0 ; i < length ; i++) {
    if(i % sizeof(u_int32_t) == 0)
      random_number = arc4random();
    entropy[i] = random_number & 0xFF;
    random_number >>= 8;
  }
  i = random_number = 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, (CC_LONG)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 = 0UL;
  OSStatus err;

  /* The SSLWrite() function works a little differently than expected. The
     fourth argument (processed) is currently documented in Apple's
     documentation as: "On return, the length, in bytes, of the data actually
     written."

     Now, one could interpret that as "written to the socket," but actually,
     it returns the amount of data that was written to a buffer internal to
     the SSLContextRef instead. So it's possible for SSLWrite() to return
     errSSLWouldBlock and a number of bytes "written" because those bytes were
     encrypted and written to a buffer, not to the socket.

     So if this happens, then we need to keep calling SSLWrite() over and
     over again with no new data until it quits returning errSSLWouldBlock. */

  /* Do we have buffered data to write from the last time we were called? */
  if(connssl->ssl_write_buffered_length) {
    /* Write the buffered data: */
    err = SSLWrite(connssl->ssl_ctx, NULL, 0UL, &processed);
    switch (err) {
      case noErr:
        /* processed is always going to be 0 because we didn't write to
           the buffer, so return how much was written to the socket */
        processed = connssl->ssl_write_buffered_length;
        connssl->ssl_write_buffered_length = 0UL;
        break;
      case errSSLWouldBlock: /* argh, try again */
        *curlcode = CURLE_AGAIN;
        return -1L;
      default:
        failf(conn->data, "SSLWrite() returned error %d", err);
        *curlcode = CURLE_SEND_ERROR;
        return -1L;
    }
  }
  else {
    /* We've got new data to write: */
    err = SSLWrite(connssl->ssl_ctx, mem, len, &processed);
    if(err != noErr) {
      switch (err) {
        case errSSLWouldBlock:
          /* Data was buffered but not sent, we have to tell the caller
             to try sending again, and remember how much was buffered */
          connssl->ssl_write_buffered_length = len;
          *curlcode = CURLE_AGAIN;
          return -1L;
        default:
          failf(conn->data, "SSLWrite() returned error %d", err);
          *curlcode = CURLE_SEND_ERROR;
          return -1L;
      }
    }
  }
  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 = 0UL;
  OSStatus err = SSLRead(connssl->ssl_ctx, buf, buffersize, &processed);

  if(err != noErr) {
    switch (err) {
      case errSSLWouldBlock:  /* return how much we read (if anything) */
        if(processed)
          return (ssize_t)processed;
        *curlcode = CURLE_AGAIN;
        return -1L;
        break;

      /* errSSLClosedGraceful - server gracefully shut down the SSL session
         errSSLClosedNoNotify - server hung up on us instead of sending a
           closure alert notice, read() is returning 0
         Either way, inform the caller that the server disconnected. */
      case errSSLClosedGraceful:
      case errSSLClosedNoNotify:
        *curlcode = CURLE_OK;
        return -1L;
        break;

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

#endif /* USE_DARWINSSL */