[GitHub] [trafficserver] sudheerv commented on a change in pull request #7516: Adding TCP Info header support to header rewrite

[GitBox <gi...@apache.org>]

sudheerv commented on a change in pull request #7516:
URL: https://github.com/apache/trafficserver/pull/7516#discussion_r604354461



##########
File path: plugins/header_rewrite/conditions.cc
##########
@@ -1333,4 +1344,71 @@ ConditionSessionTransactCount::append_value(std::string &s, Resources const &res
     TSDebug(PLUGIN_NAME, "Appending SSN-TXN-COUNT %s to evaluation value %.*s", _qualifier.c_str(), length, value);
     s.append(value, length);
   }
-}
\ No newline at end of file
+}
+
+void
+ConditionTcpInfo::initialize(Parser &p)
+{
+  Condition::initialize(p);
+  TSDebug(PLUGIN_NAME, "Initializing TCP Info");
+  MatcherType *match     = new MatcherType(_cond_op);
+  std::string const &arg = p.get_arg();
+
+  match->set(strtol(arg.c_str(), nullptr, 10));
+  _matcher = match;
+}
+
+void
+ConditionTcpInfo::initialize_hooks()
+{
+  add_allowed_hook(TS_HTTP_TXN_START_HOOK);
+  add_allowed_hook(TS_HTTP_TXN_CLOSE_HOOK);
+  add_allowed_hook(TS_HTTP_SEND_RESPONSE_HDR_HOOK);
+}
+
+bool
+ConditionTcpInfo::eval(const Resources &res)
+{
+  std::string s;
+
+  append_value(s, res);
+  bool rval = static_cast<const Matchers<std::string> *>(_matcher)->test(s);
+
+  TSDebug(PLUGIN_NAME, "Evaluating TCP-Info: %s - rval: %d", s.c_str(), rval);
+
+  return rval;
+}
+
+void
+ConditionTcpInfo::append_value(std::string &s, Resources const &res)
+{
+#if defined(TCP_INFO) && defined(HAVE_STRUCT_TCP_INFO)
+  TSReturnCode tsSsn;
+  int fd;
+  struct tcp_info info;
+  socklen_t tcp_info_len = sizeof(info);
+  tsSsn                  = TSHttpTxnClientFdGet(res.txnp, &fd);
+  if (tsSsn != TS_SUCCESS || fd <= 0) {

Review comment:
       To @zwoop 's point, I wonder how this would work for "internal" (PluginVC) transactions, as there is no real client socket involved for those transactions. We could either (a) not allow adding TCP-INFO for those transactions OR (b) ensure we handle it gracefully - ie fill it with some dummy values. 
   
   My preference is for (a) as long as we document it.




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