new files to track how long it's been since data's been received from

a UDP address.  The idea's that when there's too long a gap the
address has likely been recycled and we shouldn't send replies to
packets received before the reset.

xwords4/relay/Makefile

@@ -34,6 +34,7 @@ SRC = \
 	devmgr.cpp \
 	udpqueue.cpp \
 	udpack.cpp \
+	udpager.cpp \
 	xwrelay.cpp \
 
 # STATIC ?= -static

xwords4/relay/udpager.cpp

@@ -0,0 +1,89 @@
+/* -*- compile-command: "make -k -j3"; -*- */
+
+/* 
+ * Copyright 2013 by Eric House (xwords@eehouse.org).  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include <glib.h>
+
+#include "udpager.h"
+#include "configs.h"
+#include "mlock.h"
+
+static UDPAger* s_instance = NULL;
+
+/* static */ UDPAger*
+UDPAger::Get() 
+{
+    if ( NULL == s_instance ) {
+        s_instance = new UDPAger();
+    }
+    return s_instance;
+} /* Get */
+
+UDPAger::UDPAger()
+{
+    if ( !RelayConfigs::GetConfigs()-> GetValueFor( "UDP_RECYLE_INTERVAL",
+                                                    &m_maxInterval ) ) {
+        assert(0);
+    }
+    logf( XW_LOGINFO, "read %d from configs for UDP_RECYLE_INTERVAL", 
+          m_maxInterval );
+    m_maxInterval *= 1000;      // make it milliseconds
+
+    pthread_mutex_init( &m_addrTimeMapLock, NULL );
+}
+
+// An address is valid as long as we keep hearing from it within a certain
+// frequency.  When we hear from it but it's been too long, assume it's new
+// and give it a new timestamp.
+void
+UDPAger::Refresh( const AddrInfo* addr )
+{
+    const AddrInfo::AddrUnion* saddr = addr->saddr();
+    uint32_t readWhen = addr->created();
+    gchar* b64 = g_base64_encode( (unsigned char*)&saddr->u.addr, 
+                                  sizeof(saddr->u.addr) );
+
+    MutexLock ml( &m_addrTimeMapLock );
+
+    map<AddrInfo::AddrUnion, AgePair*>::iterator iter = 
+        m_addrTimeMap.find( *saddr ); 
+    if ( m_addrTimeMap.end() == iter ) { // it's new; just insert
+        AgePair* ap = new AgePair( readWhen, readWhen );
+        m_addrTimeMap.insert( pair<AddrInfo::AddrUnion, 
+                              AgePair*>(*saddr, ap ) );
+            logf( XW_LOGINFO, "%s: adding '%s'", __func__, b64 );
+    } else {
+        AgePair* ap = iter->second;
+        assert( ap->lastSeen() <= readWhen );
+        int interval = readWhen - ap->lastSeen();
+        if ( m_maxInterval >= interval ) {
+            logf( XW_LOGINFO, "%s: refreshing '%s'; last seen %d "
+                  "milliseconds ago", __func__, b64, interval );
+            ap->update( readWhen );
+        } else {
+            logf( XW_LOGINFO, "%s: RESETTING '%s'; last seen %d "
+                  "milliseconds ago", __func__, b64, interval );
+            delete ap;
+            iter->second = new AgePair( readWhen, readWhen );
+        }
+    }
+
+    g_free( b64 );
+}
+

xwords4/relay/udpager.h

@@ -0,0 +1,60 @@
+/* -*-mode: C; fill-column: 78; c-basic-offset: 4; -*- */
+/* 
+ * Copyright 2013 by Eric House (xwords@eehouse.org).  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#ifndef _UDPAGER_H_
+#define _UDPAGER_H_
+
+#include <map>
+
+#include "addrinfo.h"
+
+using namespace std;
+
+class UDPAger {
+ public:
+    static UDPAger* Get();
+    UDPAger();
+    void Refresh( const AddrInfo* addr );
+
+ private:
+
+    class AgePair {
+    public:
+        AgePair( uint32_t created, uint32_t lastSeen ) {
+            m_created = created;
+            m_lastSeen = lastSeen;
+        }
+        void update( uint32_t lastSeen ) { m_lastSeen = lastSeen; }
+        uint32_t lastSeen() { return m_lastSeen; }
+    private:
+        uint32_t m_created;
+        uint32_t m_lastSeen;
+    };
+
+    /* Map socket addresses against times, moving the time forward only
+       when it's been too long since we saw it. */
+    int m_maxInterval;          /* config: how long since we heard */
+
+    map<AddrInfo::AddrUnion, AgePair*> m_addrTimeMap; 
+    pthread_mutex_t m_addrTimeMapLock;
+
+
+};
+
+#endif

xwords4/relay/xwrelay.conf_tmplate

@@ -27,7 +27,9 @@ GAME_PORTS=10997
 DEVICE_PORTS=10998
 
 # Port for per-device UDP interface (experimental)
-UDPPORT=10997
+UDP_PORT=10997
+# How long after we've read from an address before we assume it's recycled
+UDP_RECYLE_INTERVAL=60
 
 # default 5
 SOCK_TIMEOUT_SECONDS=5

xwords4/relay/xwrelay.cpp

@@ -80,6 +80,7 @@
 #include "devmgr.h"
 #include "udpqueue.h"
 #include "udpack.h"
+#include "udpager.h"
 
 typedef struct _UDPHeader {
     uint32_t packetID;
@@ -1499,6 +1500,7 @@ read_udp_packet( int udpsock )
 #endif
 
         AddrInfo addr( udpsock, &saddr, false );
+        UDPAger::Get()->Refresh( &addr );
         UdpQueue::get()->handle( &addr, buf, nRead, handle_udp_packet );
     }
 }
@@ -1744,7 +1746,7 @@ main( int argc, char** argv )
         (void)cfg->GetValueFor( "CTLPORT", &ctrlport );
     }
     if ( -1 == udpport ) {
-        (void)cfg->GetValueFor( "UDPPORT", &udpport );
+        (void)cfg->GetValueFor( "UDP_PORT", &udpport );
     }
 #ifdef DO_HTTP
     if ( httpport == 0 ) {