Function process_input_ssl

c/src/ssl/schannel.cpp:1627–1766

// Read up to "available" bytes from the network, decrypt it and pass plaintext to application.

static ssize_t process_input_ssl(pn_transport_t *transport, unsigned int layer, const char *input_data, size_t available)
{
  pni_ssl_t *ssl = transport->ssl;
  ssl_log( transport, PN_LEVEL_TRACE, "process_input_ssl( data size=%zu )",available );
  ssize_t consumed = 0;
  ssize_t forwarded = 0;
  bool new_app_input;

  if (available == 0) {
    // No more inbound network data
    read_closed(transport, layer, 0);
    return 0;
  }

  do {
    if (ssl->sc_input_shutdown) {
      // TLS protocol shutdown detected on input, so we are done.
      read_closed(transport, layer, 0);
      return PN_EOS;
    }

    // sc_inbuf should be ready for new or additional network encrypted bytes.
    // i.e. no straggling decrypted bytes pending.
    assert(ssl->in_data_count == 0 && ssl->decrypting);
    new_app_input = false;
    size_t count;

    if (ssl->state != RUNNING) {
      count = _pni_min(ssl->sc_in_size - ssl->sc_in_count, available);
    } else {
      // look for TLS record boundaries
      if (ssl->sc_in_count < 5) {
        ssl->sc_in_incomplete = true;
        size_t hc = _pni_min(available, 5 - ssl->sc_in_count);
        memmove(ssl->sc_inbuf + ssl->sc_in_count, input_data, hc);
        ssl->sc_in_count += hc;
        input_data += hc;
        available -= hc;
        consumed += hc;
        if (ssl->sc_in_count < 5 || available == 0)
          break;
      }

      // Top up sc_inbuf from network input_data hoping for a complete TLS Record
      // We try to guess the length as an optimization, but let SChannel
      // ultimately decide if there is spoofing going on.
      unsigned char low = (unsigned char) ssl->sc_inbuf[4];
      unsigned char high = (unsigned char) ssl->sc_inbuf[3];
      size_t rec_len = high * 256 + low + 5;
      if (rec_len < 5 || rec_len == ssl->sc_in_count || rec_len > ssl->sc_in_size)
        rec_len = ssl->sc_in_size;

      count = _pni_min(rec_len - ssl->sc_in_count, available);
    }

    if (count > 0) {
      memmove(ssl->sc_inbuf + ssl->sc_in_count, input_data, count);
      ssl->sc_in_count += count;