Function TSRemapDoRemap

example/plugins/c-api/query_remap/query_remap.cc:116–170

}

TSRemapStatus
TSRemapDoRemap(void *ih, TSHttpTxn rh ATS_UNUSED, TSRemapRequestInfo *rri)
{
  query_remap_info *qri = static_cast<query_remap_info *>(ih);

  if (!qri || !rri) {
    TSError("[%s] null private data or RRI", PLUGIN_NAME);
    return TSREMAP_NO_REMAP;
  }

  int         req_query_len;
  const char *req_query = TSUrlHttpQueryGet(rri->requestBufp, rri->requestUrl, &req_query_len);

  if (req_query && req_query_len > 0) {
    char *q, *key;
    char *s       = nullptr;
    int   hostidx = -1;

    /* make a copy of the query, as it is read only */
    q = TSstrndup(req_query, req_query_len + 1);

    /* parse query parameters */
    for (key = strtok_r(q, "&", &s); key != nullptr;) {
      char *val = strchr(key, '=');
      if (val && static_cast<size_t>(val - key) == qri->param_len && !strncmp(key, qri->param_name, qri->param_len)) {
        ++val;
        /* the param key matched the configured param_name
           hash the param value to pick a host */
        hostidx = hash_fnv32(val, strlen(val)) % static_cast<uint32_t>(qri->num_hosts);
        Dbg(dbg_ctl, "modifying host based on %s", key);
        break;
      }
      key = strtok_r(nullptr, "&", &s);
    }

    TSfree(q);

    if (hostidx >= 0) {
      int req_host_len;
      /* TODO: Perhaps use dbg_ctl.on() before calling TSUrlHostGet()... */
      const char *req_host = TSUrlHostGet(rri->requestBufp, rri->requestUrl, &req_host_len);

      if (TSUrlHostSet(rri->requestBufp, rri->requestUrl, qri->hosts[hostidx], strlen(qri->hosts[hostidx])) != TS_SUCCESS) {
        Dbg(dbg_ctl, "Failed to modify the Host in request URL");
        return TSREMAP_NO_REMAP;
      }
      Dbg(dbg_ctl, "host changed from [%.*s] to [%s]", req_host_len, req_host, qri->hosts[hostidx]);
      return TSREMAP_DID_REMAP; /* host has been modified */
    }
  }

  /* the request was not modified, TS will use the toURL from the remap rule */
  Dbg(dbg_ctl, "request not modified");
  return TSREMAP_NO_REMAP;
}

/* FNV (Fowler/Noll/Vo) hash
   (description: http://www.isthe.com/chongo/tech/comp/fnv/index.html) */