schannel.c

          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) {
    DWORD winver_full, winver_major, winver_minor;
    winver_full = GetVersion();
    winver_major = (DWORD)(LOBYTE(LOWORD(winver_full)));
    winver_minor = (DWORD)(HIBYTE(LOWORD(winver_full)));

    if(winver_major == 5 && winver_minor == 0 && 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 http://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 */