Function EscalateResponse

plugins/escalate/escalate.cc:98–181

///////////////////////////////////////////////////////////////////////////////////// Main continuation for the plugin, examining an origin response for a potential retry.

// Main continuation for the plugin, examining an origin response for a potential retry.
//
static int
EscalateResponse(TSCont cont, TSEvent event, void *edata)
{
  TSHttpTxn        txn = static_cast<TSHttpTxn>(edata);
  EscalationState *es  = static_cast<EscalationState *>(TSContDataGet(cont));
  TSMBuffer        mbuf;
  TSMLoc           hdrp, url;

  TSAssert(event == TS_EVENT_HTTP_READ_RESPONSE_HDR || event == TS_EVENT_HTTP_SEND_RESPONSE_HDR);
  bool const processing_connection_error = (event == TS_EVENT_HTTP_SEND_RESPONSE_HDR);

  if (processing_connection_error) {
    TSServerState const state = TSHttpTxnServerStateGet(txn);
    if (state == TS_SRVSTATE_CONNECTION_ALIVE) {
      // There is no connection error, so nothing to do.
      TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
      return TS_EVENT_NONE;
    }
  }

  int const tries = TSHttpTxnRedirectRetries(txn);
  if (0 != tries) { // ToDo: Future support for more than one retry-URL
    Dbg(dbg_ctl, "Not pursuing failover due previous redirect already, num tries: %d", tries);
    TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
    return TS_EVENT_NONE;
  }

  int ret = 0;
  if (processing_connection_error) {
    ret = TSHttpTxnClientRespGet(txn, &mbuf, &hdrp);
  } else {
    ret = TSHttpTxnServerRespGet(txn, &mbuf, &hdrp);
  }
  if (TS_SUCCESS != ret) {
    TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
    return TS_EVENT_NONE;
  }

  // Next, the response status ...
  TSHttpStatus const status = TSHttpHdrStatusGet(mbuf, hdrp);
  TSHandleMLocRelease(mbuf, TS_NULL_MLOC, hdrp);

  // See if we have an escalation retry config for this response code.
  auto const entry = es->status_map.find(status);
  if (entry == es->status_map.end()) {
    TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
    return TS_EVENT_NONE;
  }
  EscalationState::RetryInfo const &retry_info = entry->second;

  Dbg(dbg_ctl, "Handling failover redirect for HTTP status %d", status);
  char const *url_str = nullptr;
  int         url_len = 0;
  if (EscalationState::RETRY_URL == retry_info.type) {
    url_str = TSstrdup(retry_info.target.c_str());
    url_len = retry_info.target.size();
    Dbg(dbg_ctl, "Setting new URL to %.*s", url_len, url_str);
  } else if (EscalationState::RETRY_HOST == retry_info.type) {