Function XScanRequestHeaders

plugins/xdebug/xdebug.cc:660–784

Scan the client request headers and determine which debug headers they want in the response.

// Scan the client request headers and determine which debug headers they
// want in the response.
static int
XScanRequestHeaders(TSCont /* contp */, TSEvent event, void *edata)
{
  TSHttpTxn txn      = static_cast<TSHttpTxn>(edata);
  unsigned  xheaders = 0;
  intmax_t  fwdCnt   = 0;
  TSMLoc    field, next;
  TSMBuffer buffer;
  TSMLoc    hdr;

  // Make sure TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE) is called before exiting function.
  //
  ts::PostScript ps([=]() -> void { TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE); });

  TSReleaseAssert(event == TS_EVENT_HTTP_READ_REQUEST_HDR);

  if (TSHttpTxnClientReqGet(txn, &buffer, &hdr) == TS_ERROR) {
    return TS_EVENT_NONE;
  }

  Dbg(dbg_ctl, "scanning for %s header values", xDebugHeader.str);

  // Walk the X-Debug header values and determine what to inject into the response.
  field = TSMimeHdrFieldFind(buffer, hdr, xDebugHeader.str, xDebugHeader.len);
  while (field != TS_NULL_MLOC) {
    int count = TSMimeHdrFieldValuesCount(buffer, hdr, field);

    for (int i = 0; i < count; ++i) {
      const char *value;
      int         vsize;

      value = TSMimeHdrFieldValueStringGet(buffer, hdr, field, i, &vsize);
      if (value == nullptr || vsize == 0) {
        continue;
      }
      Dbg(dbg_ctl, "Validating value: '%.*s'", vsize, value);

#define header_field_eq(name, vptr, vlen) (((int)name.size() == vlen) && (strncasecmp(name.data(), vptr, vlen) == 0))

      if (header_field_eq(HEADER_NAME_X_CACHE_KEY, value, vsize)) {
        xheaders |= XHEADER_X_CACHE_KEY & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_CACHE_INFO, value, vsize)) {
        xheaders |= XHEADER_X_CACHE_INFO & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_MILESTONES, value, vsize)) {
        xheaders |= XHEADER_X_MILESTONES & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_CACHE, value, vsize)) {
        xheaders |= XHEADER_X_CACHE & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_GENERATION, value, vsize)) {
        xheaders |= XHEADER_X_GENERATION & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_TRANSACTION_ID, value, vsize)) {
        xheaders |= XHEADER_X_TRANSACTION_ID & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_X_REMAP, value, vsize)) {
        xheaders |= XHEADER_X_REMAP & allowedHeaders;
      } else if (header_field_eq(HEADER_NAME_VIA, value, vsize) && (XHEADER_VIA & allowedHeaders)) {
        // If the client requests the Via header, enable verbose Via debugging for this transaction.
        TSHttpTxnConfigIntSet(txn, TS_CONFIG_HTTP_INSERT_RESPONSE_VIA_STR, 3);
      } else if (header_field_eq(HEADER_NAME_DIAGS, value, vsize) && (XHEADER_DIAGS & allowedHeaders)) {
        // Enable diagnostics for DebugTxn()'s only