schannel.c

    /* once a server has indicated shutdown there is no more encrypted data */
    infof(data, "schannel: server indicated shutdown in a prior call\n");
    goto cleanup;
  }
  else if(!len) {
    /* It's debatable what to return when !len. Regardless we can't return
    immediately because there may be data to decrypt (in the case we want to
    decrypt all encrypted cached data) so handle !len later in cleanup.
    */
    ; /* do nothing */
  }
  else if(!connssl->recv_connection_closed) {
    /* increase enc buffer in order to fit the requested amount of data */
    size = connssl->encdata_length - connssl->encdata_offset;
    if(size < CURL_SCHANNEL_BUFFER_FREE_SIZE ||
       connssl->encdata_length < min_encdata_length) {
      reallocated_length = connssl->encdata_offset +
                           CURL_SCHANNEL_BUFFER_FREE_SIZE;
      if(reallocated_length < min_encdata_length) {
        reallocated_length = min_encdata_length;
      }
      reallocated_buffer = realloc(connssl->encdata_buffer,
                                   reallocated_length);
      if(reallocated_buffer == NULL) {
        *err = CURLE_OUT_OF_MEMORY;
        failf(data, "schannel: unable to re-allocate memory");
        goto cleanup;
      }

      connssl->encdata_buffer = reallocated_buffer;
      connssl->encdata_length = reallocated_length;
      size = connssl->encdata_length - connssl->encdata_offset;
      infof(data, "schannel: encdata_buffer resized %zu\n",
            connssl->encdata_length);
    }

    infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n",
          connssl->encdata_offset, connssl->encdata_length);

    /* read encrypted data from socket */
    *err = Curl_read_plain(conn->sock[sockindex],
                           (char *)(connssl->encdata_buffer +
                                    connssl->encdata_offset),
                           size, &nread);
    if(*err) {
      nread = -1;
      if(*err == CURLE_AGAIN)
        infof(data, "schannel: Curl_read_plain returned CURLE_AGAIN\n");
      else if(*err == CURLE_RECV_ERROR)
        infof(data, "schannel: Curl_read_plain returned CURLE_RECV_ERROR\n");
      else
        infof(data, "schannel: Curl_read_plain returned error %d\n", *err);
    }
    else if(nread == 0) {
      connssl->recv_connection_closed = true;
      infof(data, "schannel: server closed the connection\n");
    }
    else if(nread > 0) {
      connssl->encdata_offset += (size_t)nread;
      infof(data, "schannel: encrypted data got %zd\n", nread);
    }
  }

  infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n",
        connssl->encdata_offset, connssl->encdata_length);

  /* decrypt loop */
  while(connssl->encdata_offset > 0 && sspi_status == SEC_E_OK &&
        (!len || connssl->decdata_offset < len ||
         connssl->recv_connection_closed)) {
    /* prepare data buffer for DecryptMessage call */
    InitSecBuffer(&inbuf[0], SECBUFFER_DATA, connssl->encdata_buffer,
                  curlx_uztoul(connssl->encdata_offset));

    /* we need 3 more empty input buffers for possible output */
    InitSecBuffer(&inbuf[1], SECBUFFER_EMPTY, NULL, 0);
    InitSecBuffer(&inbuf[2], SECBUFFER_EMPTY, NULL, 0);
    InitSecBuffer(&inbuf[3], SECBUFFER_EMPTY, NULL, 0);
    InitSecBufferDesc(&inbuf_desc, inbuf, 4);

    /* https://msdn.microsoft.com/en-us/library/windows/desktop/aa375348.aspx
       */
    sspi_status = s_pSecFn->DecryptMessage(&connssl->ctxt->ctxt_handle,
                                           &inbuf_desc, 0, NULL);

    /* check if everything went fine (server may want to renegotiate
       or shutdown the connection context) */
    if(sspi_status == SEC_E_OK || sspi_status == SEC_I_RENEGOTIATE ||
       sspi_status == SEC_I_CONTEXT_EXPIRED) {
      /* check for successfully decrypted data, even before actual
         renegotiation or shutdown of the connection context */
      if(inbuf[1].BufferType == SECBUFFER_DATA) {
        infof(data, "schannel: decrypted data length: %lu\n",
              inbuf[1].cbBuffer);

        /* increase buffer in order to fit the received amount of data */
        size = inbuf[1].cbBuffer > CURL_SCHANNEL_BUFFER_FREE_SIZE ?
               inbuf[1].cbBuffer : CURL_SCHANNEL_BUFFER_FREE_SIZE;
        if(connssl->decdata_length - connssl->decdata_offset < size ||
           connssl->decdata_length < len) {
          /* increase internal decrypted data buffer */
          reallocated_length = connssl->decdata_offset + size;
          /* make sure that the requested amount of data fits */
          if(reallocated_length < len) {
            reallocated_length = len;
          }
          reallocated_buffer = realloc(connssl->decdata_buffer,
                                       reallocated_length);
          if(reallocated_buffer == NULL) {
            *err = CURLE_OUT_OF_MEMORY;
            failf(data, "schannel: unable to re-allocate memory");
            goto cleanup;
          }
          connssl->decdata_buffer = reallocated_buffer;
          connssl->decdata_length = reallocated_length;
        }

        /* copy decrypted data to internal buffer */
        size = inbuf[1].cbBuffer;
        if(size) {
          memcpy(connssl->decdata_buffer + connssl->decdata_offset,
                 inbuf[1].pvBuffer, size);
          connssl->decdata_offset += size;
        }

        infof(data, "schannel: decrypted data added: %zu\n", size);
        infof(data, "schannel: decrypted data cached: offset %zu length %zu\n",
              connssl->decdata_offset, connssl->decdata_length);
      }

      /* check for remaining encrypted data */
      if(inbuf[3].BufferType == SECBUFFER_EXTRA && inbuf[3].cbBuffer > 0) {
        infof(data, "schannel: encrypted data length: %lu\n",
              inbuf[3].cbBuffer);

        /* check if the remaining data is less than the total amount
         * and therefore begins after the already processed data
         */
        if(connssl->encdata_offset > inbuf[3].cbBuffer) {
          /* move remaining encrypted data forward to the beginning of
             buffer */
          memmove(connssl->encdata_buffer,
                  (connssl->encdata_buffer + connssl->encdata_offset) -
                  inbuf[3].cbBuffer, inbuf[3].cbBuffer);
          connssl->encdata_offset = inbuf[3].cbBuffer;
        }

        infof(data, "schannel: encrypted data cached: offset %zu length %zu\n",
              connssl->encdata_offset, connssl->encdata_length);
      }
      else {
        /* reset encrypted buffer offset, because there is no data remaining */
        connssl->encdata_offset = 0;
      }

      /* check if server wants to renegotiate the connection context */
      if(sspi_status == SEC_I_RENEGOTIATE) {
        infof(data, "schannel: remote party requests renegotiation\n");
        if(*err && *err != CURLE_AGAIN) {
          infof(data, "schannel: can't renogotiate, an error is pending\n");
          goto cleanup;
        }
        if(connssl->encdata_offset) {
          *err = CURLE_RECV_ERROR;
          infof(data, "schannel: can't renogotiate, "
                      "encrypted data available\n");
          goto cleanup;
        }
        /* begin renegotiation */
        infof(data, "schannel: renegotiating SSL/TLS connection\n");
        connssl->state = ssl_connection_negotiating;
        connssl->connecting_state = ssl_connect_2_writing;
        *err = schannel_connect_common(conn, sockindex, FALSE, &done);
        if(*err) {
          infof(data, "schannel: renegotiation failed\n");
          goto cleanup;
        }
        /* now retry receiving data */
        sspi_status = SEC_E_OK;
        infof(data, "schannel: SSL/TLS connection renegotiated\n");
        continue;
      }
      /* check if the server closed the connection */
      else if(sspi_status == SEC_I_CONTEXT_EXPIRED) {
        /* In Windows 2000 SEC_I_CONTEXT_EXPIRED (close_notify) is not
           returned so we have to work around that in cleanup. */
        connssl->recv_sspi_close_notify = true;
        if(!connssl->recv_connection_closed) {
          connssl->recv_connection_closed = true;
          infof(data, "schannel: server closed the connection\n");
        }
        goto cleanup;
      }
    }
    else if(sspi_status == SEC_E_INCOMPLETE_MESSAGE) {
      if(!*err)
        *err = CURLE_AGAIN;
      infof(data, "schannel: failed to decrypt data, need more data\n");
      goto cleanup;
    }
    else {
      *err = CURLE_RECV_ERROR;
      infof(data, "schannel: failed to read data from server: %s\n",
            Curl_sspi_strerror(conn, sspi_status));
      goto cleanup;
    }
  }

  infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n",
        connssl->encdata_offset, connssl->encdata_length);

  infof(data, "schannel: decrypted data buffer: offset %zu length %zu\n",
        connssl->decdata_offset, connssl->decdata_length);

cleanup:
  /* Warning- there is no guarantee the encdata state is valid at this point */
  infof(data, "schannel: schannel_recv cleanup\n");

  /* Error if the connection has closed without a close_notify.
  Behavior here is a matter of debate. We don't want to be vulnerable to a
  truncation attack however there's some browser precedent for ignoring the
  close_notify for compatibility reasons.
  Additionally, Windows 2000 (v5.0) is a special case since it seems it doesn't
  return close_notify. In that case if the connection was closed we assume it
  was graceful (close_notify) since there doesn't seem to be a way to tell.
  */
  if(len && !connssl->decdata_offset && connssl->recv_connection_closed &&
     !connssl->recv_sspi_close_notify) {
    bool isWin2k = FALSE;

#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
    OSVERSIONINFO osver;

    memset(&osver, 0, sizeof(osver));
    osver.dwOSVersionInfoSize = sizeof(osver);

    /* Find out the Windows version */
    if(GetVersionEx(&osver)) {
      /* Verify the version number is 5.0 */
      if(osver.dwMajorVersion == 5 && osver.dwMinorVersion == 0)
        isWin2k = TRUE;
    }
#else
    ULONGLONG cm;
    OSVERSIONINFOEX osver;

    memset(&osver, 0, sizeof(osver));
    osver.dwOSVersionInfoSize = sizeof(osver);
    osver.dwMajorVersion = 5;

    cm = VerSetConditionMask(0, VER_MAJORVERSION, VER_EQUAL);
    cm = VerSetConditionMask(cm, VER_MINORVERSION, VER_EQUAL);
    cm = VerSetConditionMask(cm, VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL);
    cm = VerSetConditionMask(cm, VER_SERVICEPACKMINOR, VER_GREATER_EQUAL);

    if(VerifyVersionInfo(&osver, (VER_MAJORVERSION | VER_MINORVERSION |
                                  VER_SERVICEPACKMAJOR | VER_SERVICEPACKMINOR),
                         cm))
      isWin2k = TRUE;
#endif

    if(isWin2k && sspi_status == SEC_E_OK)
      connssl->recv_sspi_close_notify = true;
    else {
      *err = CURLE_RECV_ERROR;
      infof(data, "schannel: server closed abruptly (missing close_notify)\n");
    }
  }

  /* Any error other than CURLE_AGAIN is an unrecoverable error. */
  if(*err && *err != CURLE_AGAIN)
      connssl->recv_unrecoverable_err = *err;

  size = len < connssl->decdata_offset ? len : connssl->decdata_offset;
  if(size) {
    memcpy(buf, connssl->decdata_buffer, size);
    memmove(connssl->decdata_buffer, connssl->decdata_buffer + size,
            connssl->decdata_offset - size);
    connssl->decdata_offset -= size;

    infof(data, "schannel: decrypted data returned %zu\n", size);
    infof(data, "schannel: decrypted data buffer: offset %zu length %zu\n",
          connssl->decdata_offset, connssl->decdata_length);
    *err = CURLE_OK;
    return (ssize_t)size;
  }

  if(!*err && !connssl->recv_connection_closed)
      *err = CURLE_AGAIN;

  /* It's debatable what to return when !len. We could return whatever error we
  got from decryption but instead we override here so the return is consistent.
  */
  if(!len)
    *err = CURLE_OK;

  return *err ? -1 : 0;
}

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

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

  result = schannel_connect_common(conn, sockindex, FALSE, &done);
  if(result)
    return result;

  DEBUGASSERT(done);

  return CURLE_OK;
}

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

  if(connssl->use) /* SSL/TLS is in use */
    return (connssl->encdata_offset > 0 ||
            connssl->decdata_offset > 0 ) ? TRUE : FALSE;
  else
    return FALSE;
}

void Curl_schannel_close(struct connectdata *conn, int sockindex)
{
  if(conn->ssl[sockindex].use)
    /* if the SSL/TLS channel hasn't been shut down yet, do that now. */
    Curl_ssl_shutdown(conn, sockindex);
}

int Curl_schannel_shutdown(struct connectdata *conn, int sockindex)
{
  /* See https://msdn.microsoft.com/en-us/library/windows/desktop/aa380138.aspx
   * Shutting Down an Schannel Connection
   */
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];

  infof(data, "schannel: shutting down SSL/TLS connection with %s port %hu\n",
        conn->host.name, conn->remote_port);

  if(connssl->cred && connssl->ctxt) {
    SecBufferDesc BuffDesc;
    SecBuffer Buffer;
    SECURITY_STATUS sspi_status;
    SecBuffer outbuf;
    SecBufferDesc outbuf_desc;
    CURLcode result;
    TCHAR *host_name;
    DWORD dwshut = SCHANNEL_SHUTDOWN;

    InitSecBuffer(&Buffer, SECBUFFER_TOKEN, &dwshut, sizeof(dwshut));
    InitSecBufferDesc(&BuffDesc, &Buffer, 1);

    sspi_status = s_pSecFn->ApplyControlToken(&connssl->ctxt->ctxt_handle,
                                              &BuffDesc);

    if(sspi_status != SEC_E_OK)
      failf(data, "schannel: ApplyControlToken failure: %s",
            Curl_sspi_strerror(conn, sspi_status));

    host_name = Curl_convert_UTF8_to_tchar(conn->host.name);
    if(!host_name)
      return CURLE_OUT_OF_MEMORY;

    /* setup output buffer */
    InitSecBuffer(&outbuf, SECBUFFER_EMPTY, NULL, 0);
    InitSecBufferDesc(&outbuf_desc, &outbuf, 1);

    sspi_status = s_pSecFn->InitializeSecurityContext(
      &connssl->cred->cred_handle,
      &connssl->ctxt->ctxt_handle,
      host_name,
      connssl->req_flags,
      0,
      0,
      NULL,
      0,
      &connssl->ctxt->ctxt_handle,
      &outbuf_desc,
      &connssl->ret_flags,
      &connssl->ctxt->time_stamp);

    Curl_unicodefree(host_name);

    if((sspi_status == SEC_E_OK) || (sspi_status == SEC_I_CONTEXT_EXPIRED)) {
      /* send close message which is in output buffer */
      ssize_t written;
      result = Curl_write_plain(conn, conn->sock[sockindex], outbuf.pvBuffer,
                                outbuf.cbBuffer, &written);

      s_pSecFn->FreeContextBuffer(outbuf.pvBuffer);
      if((result != CURLE_OK) || (outbuf.cbBuffer != (size_t) written)) {
        infof(data, "schannel: failed to send close msg: %s"
              " (bytes written: %zd)\n", curl_easy_strerror(result), written);
      }
    }
  }

  /* free SSPI Schannel API security context handle */
  if(connssl->ctxt) {
    infof(data, "schannel: clear security context handle\n");
    s_pSecFn->DeleteSecurityContext(&connssl->ctxt->ctxt_handle);
    Curl_safefree(connssl->ctxt);
  }

  /* free SSPI Schannel API credential handle */
  if(connssl->cred) {
    /* decrement the reference counter of the credential/session handle */
    if(connssl->cred->refcount > 0) {
      connssl->cred->refcount--;
      infof(data, "schannel: decremented credential handle refcount = %d\n",
            connssl->cred->refcount);
    }

    /* if the handle was not cached and the refcount is zero */
    if(!connssl->cred->cached && connssl->cred->refcount == 0) {
      infof(data, "schannel: clear credential handle\n");
      s_pSecFn->FreeCredentialsHandle(&connssl->cred->cred_handle);
      Curl_safefree(connssl->cred);
    }
  }

  /* free internal buffer for received encrypted data */
  if(connssl->encdata_buffer != NULL) {
    Curl_safefree(connssl->encdata_buffer);
    connssl->encdata_length = 0;
    connssl->encdata_offset = 0;
  }

  /* free internal buffer for received decrypted data */
  if(connssl->decdata_buffer != NULL) {
    Curl_safefree(connssl->decdata_buffer);
    connssl->decdata_length = 0;
    connssl->decdata_offset = 0;
  }

  return CURLE_OK;
}

void Curl_schannel_session_free(void *ptr)
{
  struct curl_schannel_cred *cred = ptr;

  if(cred && cred->cached) {
    if(cred->refcount == 0) {
      s_pSecFn->FreeCredentialsHandle(&cred->cred_handle);
      Curl_safefree(cred);
    }
    else {
      cred->cached = FALSE;
    }
  }
}

int Curl_schannel_init(void)
{
  return (Curl_sspi_global_init() == CURLE_OK ? 1 : 0);
}

void Curl_schannel_cleanup(void)
{
  Curl_sspi_global_cleanup();
}

size_t Curl_schannel_version(char *buffer, size_t size)
{
  size = snprintf(buffer, size, "WinSSL");

  return size;
}

int Curl_schannel_random(unsigned char *entropy, size_t length)
{
  HCRYPTPROV hCryptProv = 0;

  if(!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
                          CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
    return 1;

  if(!CryptGenRandom(hCryptProv, (DWORD)length, entropy)) {
    CryptReleaseContext(hCryptProv, 0UL);
    return 1;
  }

  CryptReleaseContext(hCryptProv, 0UL);
  return 0;
}

#ifdef _WIN32_WCE
static CURLcode verify_certificate(struct connectdata *conn, int sockindex)
{
  SECURITY_STATUS status;
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  CURLcode result = CURLE_OK;
  CERT_CONTEXT *pCertContextServer = NULL;
  const CERT_CHAIN_CONTEXT *pChainContext = NULL;

  status = s_pSecFn->QueryContextAttributes(&connssl->ctxt->ctxt_handle,
                                            SECPKG_ATTR_REMOTE_CERT_CONTEXT,
                                            &pCertContextServer);

  if((status != SEC_E_OK) || (pCertContextServer == NULL)) {
    failf(data, "schannel: Failed to read remote certificate context: %s",
          Curl_sspi_strerror(conn, status));
    result = CURLE_PEER_FAILED_VERIFICATION;
  }

  if(result == CURLE_OK) {
    CERT_CHAIN_PARA ChainPara;
    memset(&ChainPara, 0, sizeof(ChainPara));
    ChainPara.cbSize = sizeof(ChainPara);

    if(!CertGetCertificateChain(NULL,
                                pCertContextServer,
                                NULL,
                                pCertContextServer->hCertStore,
                                &ChainPara,
                                (data->set.ssl_no_revoke ? 0 :
                                 CERT_CHAIN_REVOCATION_CHECK_CHAIN),
                                NULL,
                                &pChainContext)) {
      failf(data, "schannel: CertGetCertificateChain failed: %s",
            Curl_sspi_strerror(conn, GetLastError()));
      pChainContext = NULL;
      result = CURLE_PEER_FAILED_VERIFICATION;
    }

    if(result == CURLE_OK) {
      CERT_SIMPLE_CHAIN *pSimpleChain = pChainContext->rgpChain[0];
      DWORD dwTrustErrorMask = ~(DWORD)(CERT_TRUST_IS_NOT_TIME_NESTED);
      dwTrustErrorMask &= pSimpleChain->TrustStatus.dwErrorStatus;
      if(dwTrustErrorMask) {
        if(dwTrustErrorMask & CERT_TRUST_IS_REVOKED)
          failf(data, "schannel: CertGetCertificateChain trust error"
                " CERT_TRUST_IS_REVOKED");
        else if(dwTrustErrorMask & CERT_TRUST_IS_PARTIAL_CHAIN)
          failf(data, "schannel: CertGetCertificateChain trust error"
                " CERT_TRUST_IS_PARTIAL_CHAIN");
        else if(dwTrustErrorMask & CERT_TRUST_IS_UNTRUSTED_ROOT)
          failf(data, "schannel: CertGetCertificateChain trust error"
                " CERT_TRUST_IS_UNTRUSTED_ROOT");
        else if(dwTrustErrorMask & CERT_TRUST_IS_NOT_TIME_VALID)
          failf(data, "schannel: CertGetCertificateChain trust error"
                " CERT_TRUST_IS_NOT_TIME_VALID");
        else
          failf(data, "schannel: CertGetCertificateChain error mask: 0x%08x",
                dwTrustErrorMask);
        result = CURLE_PEER_FAILED_VERIFICATION;
      }
    }
  }

  if(result == CURLE_OK) {
    if(data->set.ssl.verifyhost) {
      TCHAR cert_hostname_buff[128];
      xcharp_u hostname;
      xcharp_u cert_hostname;
      DWORD len;

      cert_hostname.const_tchar_ptr = cert_hostname_buff;
      hostname.tchar_ptr = Curl_convert_UTF8_to_tchar(conn->host.name);

      /* TODO: Fix this for certificates with multiple alternative names.
      Right now we're only asking for the first preferred alternative name.
      Instead we'd need to do all via CERT_NAME_SEARCH_ALL_NAMES_FLAG
      (if WinCE supports that?) and run this section in a loop for each.
      https://msdn.microsoft.com/en-us/library/windows/desktop/aa376086.aspx
      curl: (51) schannel: CertGetNameString() certificate hostname
      (.google.com) did not match connection (google.com)
      */
      len = CertGetNameString(pCertContextServer,
                              CERT_NAME_DNS_TYPE,
                              0,
                              NULL,
                              cert_hostname.tchar_ptr,
                              128);
      if(len > 0 && *cert_hostname.tchar_ptr == '*') {
        /* this is a wildcard cert.  try matching the last len - 1 chars */
        int hostname_len = strlen(conn->host.name);
        cert_hostname.tchar_ptr++;
        if(_tcsicmp(cert_hostname.const_tchar_ptr,
                    hostname.const_tchar_ptr + hostname_len - len + 2) != 0)
          result = CURLE_PEER_FAILED_VERIFICATION;
      }
      else if(len == 0 || _tcsicmp(hostname.const_tchar_ptr,
                                   cert_hostname.const_tchar_ptr) != 0) {
        result = CURLE_PEER_FAILED_VERIFICATION;
      }
      if(result == CURLE_PEER_FAILED_VERIFICATION) {
        char *_cert_hostname;
        _cert_hostname = Curl_convert_tchar_to_UTF8(cert_hostname.tchar_ptr);
        failf(data, "schannel: CertGetNameString() certificate hostname "
              "(%s) did not match connection (%s)",
              _cert_hostname, conn->host.name);
        Curl_unicodefree(_cert_hostname);
      }
      Curl_unicodefree(hostname.tchar_ptr);
    }
  }

  if(pChainContext)
    CertFreeCertificateChain(pChainContext);

  if(pCertContextServer)
    CertFreeCertificateContext(pCertContextServer);

  return result;
}
#endif /* _WIN32_WCE */

#endif /* USE_SCHANNEL */