Avoid flooding log on each connect by testing if fast-open-connect succeeds once...

as suggested by @rgacogne.

Plus a few corrections in docs.

diff --git a/pdns/lwres.cc b/pdns/lwres.cc
index af5f6515131a403bb9eb911853d1d77b54fdb247..40da2f36c329fa5377f11c27ad4adfb5a771b675 100644 (file)
--- a/pdns/lwres.cc
+++ b/pdns/lwres.cc
@@ -332,7 +332,7 @@ LWResult::Result asyncresolve(const ComboAddress& ip, const DNSName& domain, int
           s.setFastOpenConnect();
         }
         catch (const NetworkError& e) {
-          g_log << Logger::Error << "tcp-fast-connect enabled but returned error: " << e.what() << endl;
+          // Ignore error, we did a pre-check in pdns_recursor.cc:checkTFOconnect()
         }
       }
 

diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index 921235a7330894f214d2eb781de1d654953a09b8..5d8b3c959f459f6eda703de4fe90620f044c86c8 100644 (file)
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -3236,13 +3236,25 @@ static void checkFastOpenSysctl(bool active)
     }
   }
   else {
-    g_log << Logger::Error << "Cannot determine if kernel setting allow fast-open" << endl;
+    g_log << Logger::Notice << "Cannot determine if kernel settings allow fast-open" << endl;
  }
 #else
-  g_log << Logger::Error << "Cannot determine if kernel setting allow fast-open" << endl;
+  g_log << Logger::Notice << "Cannot determine if kernel settings allow fast-open" << endl;
 #endif
 }
 
+static void checkTFOconnect()
+{
+  try {
+    Socket s(AF_INET, SOCK_STREAM);
+    s.setNonBlocking();
+    s.setFastOpenConnect();
+  }
+  catch (const NetworkError& e) {
+    g_log << Logger::Error << "tcp-fast-open-connect enabled but returned error: " << e.what() << endl;
+  }
+}
+
 static void makeTCPServerSockets(deferredAdd_t& deferredAdds, std::set<int>& tcpSockets)
 {
   int fd;
@@ -4698,6 +4710,7 @@ static int serviceMain(int argc, char*argv[])
 
   if (SyncRes::s_tcp_fast_open_connect) {
     checkFastOpenSysctl(true);
+    checkTFOconnect();
   }
 
   if(SyncRes::s_serverID.empty()) {

diff --git a/pdns/recursordist/docs/performance.rst b/pdns/recursordist/docs/performance.rst
index cdf9838d4b47ae8debae6cc913f93f6caa2fbacf..15e4b48fea9dc76279281e60e06f3b14e00bb2c4 100644 (file)
--- a/pdns/recursordist/docs/performance.rst
+++ b/pdns/recursordist/docs/performance.rst
@@ -115,7 +115,7 @@ On Linux systems, the recursor can use TCP Fast Open for passive (incoming, sinc
 TCP Fast Open allows the initial SYN packet to carry data, saving one network round-trip.
 For details, consult `:rfc:7413`.
 
-To enable TCP Fast Open, it might be need change the value of the ``net.ipv4.tcp_fastopen`` sysctl.
+To enable TCP Fast Open, it might be needed to change the value of the ``net.ipv4.tcp_fastopen`` sysctl.
 Value 0 means Fast Open is disabled, 1 is only use Fast Open for active connections, 2 is only for passive connections and 3 is for both.
 
 The operation of TCP Fast Open can be monitored by looking at these kernel metrics::
@@ -129,7 +129,7 @@ While developing active TCP Fast Open, it was needed to set ``net.ipv4.tcp_fasto
 At the moment of writing, the Google operated nameservers (both recursive and authoritative) indicate Fast Open support in the TCP handshake, but do not accept the cookie they sent previously and send a new one for each connection.
 We can only hope Google will fix this issue soon.
 
-If you operate an anycast pool of machines, make them share the TCP Fast Open Key by setting the ``net.ipv4.tcp_fastopen_key`` sysctl, otherwise you wil create a similar issue the Google servers have.
+If you operate an anycast pool of machines, make them share the TCP Fast Open Key by setting the ``net.ipv4.tcp_fastopen_key`` sysctl, otherwise you will create a similar issue the Google servers have.
 
 To determine a good value for the :ref:`setting-tcp-fast-open` setting, watch the ``TCPFastOpenListenOverflow`` metric.
 If this value increases often, the value might be too low for your traffic, but note that increasing it will use kernel resources.

diff --git a/pdns/recursordist/docs/settings.rst b/pdns/recursordist/docs/settings.rst
index 73a511a34c5eb5764f8bf2bb48e17b8ea0bc27e8..f4fc954d825ec4f9314a191bd05476daac6b674a 100644 (file)
--- a/pdns/recursordist/docs/settings.rst
+++ b/pdns/recursordist/docs/settings.rst
@@ -1849,7 +1849,7 @@ The numerical value supplied is used as the queue size, 0 meaning disabled. See
 -  Boolean
 -  Default: no (disabled)
 
-Enable TCP Fast Open Connect support, if available, on the outgoing connections to authoritatively servers. See :ref:`tcp-fast-open-support`.
+Enable TCP Fast Open Connect support, if available, on the outgoing connections to authoritative servers. See :ref:`tcp-fast-open-support`.
 
 .. _setting-threads: