implemented simple dns caching in httpd

qse/configure

@@ -20079,6 +20079,7 @@ done
 
 		if test "$ac_cv_func_quadmath_snprintf" = "no"
 		then
+
 			{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for quadmath_snprintf in -lquadmath" >&5
 $as_echo_n "checking for quadmath_snprintf in -lquadmath... " >&6; }
 if ${ac_cv_lib_quadmath_quadmath_snprintf+:} false; then :
@@ -20122,6 +20123,13 @@ if test "x$ac_cv_lib_quadmath_quadmath_snprintf" = xyes; then :
 				$as_echo "#define HAVE_QUADMATH_SNPRINTF 1" >>confdefs.h
 
 
+fi
+
+
+			if test "$ac_cv_lib_quadmath_quadmath_snprintf" = "no"
+			then
+
+				ac_cv_sizeof___float128=0
 			fi
 
 		else
@@ -20129,6 +20137,8 @@ fi
 		fi
 	fi
 
+	if test ${ac_cv_sizeof___float128} -gt 0
+	then
 		OLDLIBS="$LIBS"
 		LIBS="$LIBM $LIBS"
 		for ac_func in powq fmodq sinq cosq tanq sinhq coshq tanhq asinq acosq atanq atan2q logq log10q expq sqrtq ceilq floorq roundq
@@ -20156,6 +20166,7 @@ done
 
 		LIBS="$OLDLIBS"
 	fi
+fi
 
 
 

qse/configure.ac

@@ -435,6 +435,9 @@ then
 	)
 fi
 
+dnl Quadmath functions may not be in the default c library.
+dnl Find a library containing them. Disable the float128 type
+dnl if they are not available.
 if test ${ac_cv_sizeof___float128} -gt 0
 then
 	AC_CHECK_FUNCS([quadmath_snprintf])
@@ -447,22 +450,37 @@ then
 	
 		if test "$ac_cv_func_quadmath_snprintf" = "no"
 		then
+			dnl quadmath_snprintf not avalable in the 
+			dnl standard math lib.
+
 			AC_CHECK_LIB([quadmath], [quadmath_snprintf], [
 				QUADMATH_LIBS="-lquadmath"
 				LIBM="$LIBM -lquadmath"
 				AC_DEFINE(HAVE_QUADMATH_SNPRINTF, 1)
 			])
+
+			if test "$ac_cv_lib_quadmath_quadmath_snprintf" = "no"
+			then
+				dnl quadmath_snprintf not avalable in the 
+				dnl quadmath lib.
+
+				ac_cv_sizeof___float128=0
+			fi
+
 		else
 			QUADMATH_LIBS="$LIBM"
 		fi
 	fi
 
+	if test ${ac_cv_sizeof___float128} -gt 0
+	then
 		OLDLIBS="$LIBS"
 		LIBS="$LIBM $LIBS"
 		AC_CHECK_FUNCS([powq fmodq sinq cosq tanq sinhq coshq tanhq asinq acosq atanq atan2q logq log10q expq sqrtq ceilq floorq roundq])
 		AC_CHECK_FUNCS([strtoflt128])
 		LIBS="$OLDLIBS"
 	fi
+fi
 AC_SUBST(QUADMATH_LIBS)
 
 AC_DEFINE_UNQUOTED(QSE_SIZEOF_CHAR, ${ac_cv_sizeof_char}, [sizeof(char)])

qse/lib/http/httpd-proxy.c

@@ -1016,7 +1016,6 @@ static void task_fini_proxy (
 {
 	task_proxy_t* proxy = (task_proxy_t*)task->ctx;
 
-printf ("task_fini_proxy.................\n");
 	if (proxy->peer_status & PROXY_PEER_OPEN) 
 		httpd->opt.scb.peer.close (httpd, &proxy->peer);
 
@@ -1083,7 +1082,7 @@ static int task_main_proxy_4 (
 {
 	task_proxy_t* proxy = (task_proxy_t*)task->ctx;
 	
-#if 1
+#if 0
 printf ("task_main_proxy_4 trigger[0].mask=%d trigger[1].mask=%d trigger[2].mask=%d\n", 
 	task->trigger.v[0].mask, task->trigger.v[1].mask, task->trigger.cmask);
 #endif
@@ -1577,12 +1576,13 @@ static void on_peer_name_resolved (qse_httpd_t* httpd, const qse_mchar_t* name,
 
 	QSE_ASSERT (proxy->flags & PROXY_RESOL_PEER_NAME);
 
+	proxy->flags &= ~PROXY_RESOL_PEER_NAME;
+
 	if (nwad)
 	{
 		/* resolved successfully */
-		proxy->flags &= ~PROXY_RESOL_PEER_NAME;
-		proxy->peer.nwad = *nwad;
 		
+		proxy->peer.nwad = *nwad;
 		qse_setnwadport (&proxy->peer.nwad, qse_hton16(proxy->peer_port));
 
 		if (proxy->peer.local.type == QSE_NWAD_NX)
@@ -1620,8 +1620,21 @@ static int task_main_proxy (
 	{
 		/* arrange to resolve a host name and return */
 		QSE_ASSERT (proxy->peer_name != QSE_NULL);
-		if (qse_httpd_inactivatetasktrigger (httpd, client, task) <= -1 ||
+
-		    qse_httpd_resolname (httpd, proxy->peer_name, on_peer_name_resolved, task)) goto oops;
+		if (qse_httpd_resolname (httpd, proxy->peer_name, on_peer_name_resolved, task) <= -1) goto oops;
+
+		/* if the name could be resolved without sending a request 
+		 * in qse_httpd_resolname(), on_peer_name_resolve would be 
+		 * called. */
+		if (proxy->flags & PROXY_INIT_FAILED) 
+		{
+			if (proxy->flags & PROXY_UNKNOWN_PEER_NWAD) http_errnum = 404; /* 404 Not Found */
+			goto oops;
+		}
+
+		if ((proxy->flags & PROXY_RESOL_PEER_NAME) && 
+		    qse_httpd_inactivatetasktrigger (httpd, client, task) <= -1) goto oops;
+
 		return 1;
 	}
 

qse/lib/http/httpd-std.c

@@ -1960,43 +1960,19 @@ static void client_closed (qse_httpd_t* httpd, qse_httpd_client_t* client)
 
 
 /* ------------------------------------------------------------------- */
+#define DNS_MAX_DN_LEN 255 /* full domain name length in binary form (i.e. 3xyz2eu0) */
+#define DNS_MAX_MSG_LEN 512  /* basic dns only. no EDNS0. so 512 at most */
+
+#define DNS_MIN_TTL 10
+#define DNS_MAX_TTL 120 /* TODO: make these configurable... */
+
 typedef struct dns_ctx_t dns_ctx_t;
 typedef struct dns_req_t dns_req_t;
+typedef struct dns_ans_t dns_ans_t;
 typedef struct dns_hdr_t dns_hdr_t;
 typedef struct dns_qdtrail_t dns_qdtrail_t;
 typedef struct dns_antrail_t dns_antrail_t;
 
-struct dns_ctx_t
-{
-	qse_skad_t skad;
-	int skadlen;
-
-	qse_uint16_t seq;
-	dns_req_t* reqs[1024]; /* TOOD: choose the right size */
-};
-
-struct dns_req_t
-{
-#define DNS_REQ_A_NX (1 << 0)
-#define DNS_REQ_AAAA_NX (1 << 1)
-	int flags;
-	qse_uint16_t seqa, seqaaaa;
-
-	qse_mchar_t* name;
-	qse_uint8_t* dn;
-	qse_size_t dnlen;
-
-	qse_httpd_resol_t resol;
-	void* ctx;
-
-	qse_uint8_t qa[384];
-	qse_uint8_t qaaaa[384];
-	int qalen;
-	int qaaaalen;
-
-	dns_req_t* next;
-};
-
 enum
 {
 	DNS_OPCODE_QUERY = 0,
@@ -2083,6 +2059,50 @@ struct dns_antrail_t
 #include <qse/unpack.h>
 
 
+struct dns_ctx_t
+{
+	qse_httpd_t* httpd;
+
+	qse_skad_t skad;
+	int skadlen;
+
+	qse_uint16_t seq;
+	dns_req_t* reqs[1024]; /* TOOD: choose the right size */
+	dns_ans_t* anss[1024];
+};
+
+struct dns_req_t
+{
+	qse_mchar_t* name;
+
+#define DNS_REQ_A_NX (1 << 0)
+#define DNS_REQ_AAAA_NX (1 << 1)
+	int flags;
+	qse_uint16_t seqa, seqaaaa;
+
+	qse_uint8_t* dn;
+	qse_size_t dnlen;
+
+	qse_httpd_resol_t resol;
+	void* ctx;
+
+	qse_uint8_t qa[DNS_MAX_DN_LEN + QSE_SIZEOF(dns_hdr_t) + QSE_SIZEOF(dns_qdtrail_t)];
+	qse_uint8_t qaaaa[DNS_MAX_DN_LEN  + QSE_SIZEOF(dns_hdr_t) + QSE_SIZEOF(dns_qdtrail_t)];
+	int qalen;
+	int qaaaalen;
+
+	dns_req_t* next;
+};
+
+struct dns_ans_t
+{
+	qse_mchar_t* name; 
+	qse_nwad_t nwad;
+	qse_int64_t age;
+	qse_uint32_t ttl;
+	dns_ans_t* next;
+};
+
 #define DN_AT_END(ptr) (ptr[0] == QSE_MT('\0') || (ptr[0] == QSE_MT('.') && ptr[1] == QSE_MT('\0')))
 
 static qse_size_t to_dn (const qse_mchar_t* str, qse_uint8_t* buf, qse_size_t bufsz)
@@ -2191,6 +2211,8 @@ static int dns_open (qse_httpd_t* httpd, qse_httpd_dns_t* dns)
 	dc = (dns_ctx_t*) qse_httpd_callocmem (httpd, QSE_SIZEOF(dns_ctx_t));
 	if (dc == NULL) goto oops;
 
+	dc->httpd = httpd;
+
 /* TODO: add static cache entries from /etc/hosts */
 
 	nwad = httpd_xtn->dnsnwad;
@@ -2198,7 +2220,7 @@ static int dns_open (qse_httpd_t* httpd, qse_httpd_dns_t* dns)
 	{
 		qse_sio_t* sio;
 	#if defined(_WIN32)
-		/* TODO: */
+		/* TODO: windns.h dnsapi.lib DnsQueryConfig... */
 	#elif defined(__OS2__)
 		/* TODO: */
 	#else
@@ -2295,6 +2317,31 @@ oops:
 
 static void dns_close (qse_httpd_t* httpd, qse_httpd_dns_t* dns)
 {
+	dns_ctx_t* dc = (dns_ctx_t*)dns->ctx;
+	qse_size_t i;
+
+	for (i = 0; i < QSE_COUNTOF(dc->reqs); i++)
+	{
+		dns_req_t* next_req;
+		while (dc->reqs[i])
+		{
+			next_req = dc->reqs[i]->next;
+			qse_httpd_freemem (httpd, dc->reqs[i]);
+			dc->reqs[i] = next_req;
+		}
+	}
+
+	for (i = 0; i < QSE_COUNTOF(dc->anss); i++)
+	{
+		dns_ans_t* next_ans;
+		while (dc->anss[i])
+		{
+			next_ans = dc->anss[i]->next;
+			qse_httpd_freemem (httpd, dc->anss[i]);
+			dc->anss[i] = next_ans;
+		}
+	}
+
 #if defined(_WIN32)
 	closesocket (dns->handle.i);
 #elif defined(__OS2__)
@@ -2308,22 +2355,112 @@ static void dns_close (qse_httpd_t* httpd, qse_httpd_dns_t* dns)
 	qse_httpd_freemem (httpd, dns->ctx);
 }
 
+static unsigned long dns_hash_name (const qse_mchar_t *str)
+{
+	qse_size_t h = 0;
+	while (*str) h = ((h << 5) + h) ^ *str++;
+	return h;
+}
+
+static void dns_cache_answer (dns_ctx_t* dc, dns_req_t* req, const qse_nwad_t* nwad, qse_uint32_t ttl)
+{
+	dns_ans_t* ans, * prv, * cur;
+	qse_size_t hid;
+	qse_ntime_t now;
+
+/* TODO: implement the maximum number of entries in cache... */
+
+	/* i use the given request as a space to hold an answer.
+	 * the following assertion must be met for this to work */
+	QSE_ASSERT (QSE_SIZEOF(dns_req_t) >= QSE_SIZEOF(dns_ans_t));
+
+	qse_gettime (&now);
+
+	ans = (dns_ans_t*)req; /* shadow the request with an answer */
+	if (nwad) ans->nwad = *nwad; /* positive */
+	else ans->nwad.type = QSE_NWAD_NX; /* negative */
+	ans->age = now.sec; /* the granularity of a second should be good enough */
+
+	if (ttl < DNS_MIN_TTL) ttl = DNS_MIN_TTL; /* TODO: use configured value */
+	else if (ttl > DNS_MAX_TTL) ttl = DNS_MAX_TTL;
+
+	ans->ttl = ttl;
+	hid = dns_hash_name (req->name) % QSE_COUNTOF(dc->anss);
+
+	prv = QSE_NULL;
+	cur = dc->anss[hid];
+	while (cur)
+	{
+		if (qse_mbscasecmp(cur->name, ans->name) == 0)
+		{
+			ans->next = cur->next;
+			if (prv) prv->next = ans;
+			else dc->anss[hid] = ans;
+			qse_httpd_freemem (dc->httpd, cur);
+			return;
+		}
+
+		prv = cur;
+		cur = cur->next;
+	}
+	ans->next = dc->anss[hid];
+	dc->anss[hid] = ans;
+}
+
+static dns_ans_t* dns_get_answer_from_cache (dns_ctx_t* dc, const qse_mchar_t* name)
+{
+	dns_ans_t* prv, * cur;
+	qse_size_t hid;
+	qse_ntime_t now;
+
+	hid = dns_hash_name (name) % QSE_COUNTOF(dc->anss);
+
+	qse_gettime (&now);
+
+	prv = QSE_NULL;
+	cur = dc->anss[hid];
+	while (cur)
+	{
+		if (qse_mbscasecmp(cur->name, name) == 0)
+		{
+			if (cur->age + cur->ttl < now.sec)
+			{
+				/* entry expired. evict the entry from the cache */
+				if (prv) prv->next = cur->next;
+				else dc->anss[hid] = cur->next;
+				qse_httpd_freemem (dc->httpd, cur);
+				break;
+			}
+
+			return cur;
+		}
+
+		prv = cur;
+		cur = cur->next;
+	}
+
+	return QSE_NULL;
+}
+
 static int dns_recv (qse_httpd_t* httpd, qse_httpd_dns_t* dns)
 {
 	dns_ctx_t* dc = (dns_ctx_t*)dns->ctx;
+
 	qse_skad_t fromaddr;
 	socklen_t fromlen; /* TODO: change type */
-	qse_uint8_t buf[384];
+
+	qse_uint8_t buf[DNS_MAX_MSG_LEN];
 	qse_ssize_t len;
 	dns_hdr_t* hdr;
 
-printf ("RECV....\n");
+printf ("DNS_RECV....\n");
+
+/* TODO: delete requests that're not replied at all for long time */
 
 	fromlen = QSE_SIZEOF(fromaddr);
 	len = recvfrom (dns->handle.i, buf, QSE_SIZEOF(buf), 0, (struct sockaddr*)&fromaddr, &fromlen);
 
 /* TODO: check if fromaddr matches the dc->skad... */
-/* TODO: dns caching .... */
 
 	if (len >= QSE_SIZEOF(*hdr))
 	{
@@ -2345,7 +2482,7 @@ printf ("%d qdcount %d ancount %d\n", id, qdcount, ancount);
 			dns_req_t* req = QSE_NULL, * preq = QSE_NULL;
 			qse_size_t reclen;
 
-printf ("finding match req...\n");
+			/* inspect the question section */
 			for (i = 0; i < qdcount; i++)
 			{
 				dnlen = dn_length (plptr, pllen);
@@ -2364,7 +2501,6 @@ printf ("finding match req...\n");
 						    (qdtrail->qtype == qse_hton16(DNS_QTYPE_A) || qdtrail->qtype == qse_hton16(DNS_QTYPE_AAAA)))
 						{
 							/* found a matching request */
-printf ("found matching req...\n");
 							break;
 						}
 					}
@@ -2374,14 +2510,14 @@ printf ("found matching req...\n");
 				pllen -= reclen;
 			}
 
-			if (!req) goto done;
+			if (!req) goto done; /* no matching request for the question */
 
 			if (hdr->rcode == DNS_RCODE_NOERROR && ancount > 0)
 			{
 				dns_antrail_t* antrail;
 				qse_uint16_t qtype, anlen;
 
-printf ("checking answers.... pllen => %d\n", (int)pllen);
+				/* inspect the answer section */
 				for (i = 0; i < ancount; i++)
 				{
 					if (pllen < 1) goto done;
@@ -2389,7 +2525,6 @@ printf ("checking answers.... pllen => %d\n", (int)pllen);
 					else
 					{
 						dnlen = dn_length (plptr, pllen);
-printf ("........... %d\n", dnlen);
 						if (dnlen <= 0) goto done; /* invalid dn name */
 					}
 
@@ -2403,39 +2538,38 @@ printf ("........... %d\n", dnlen);
 					qtype = qse_ntoh16(antrail->qtype);
 					anlen = qse_ntoh16(antrail->dlen);
 
-					if (antrail->qclass == qse_hton16(DNS_QCLASS_IN))
+					if (qse_ntoh16(antrail->qclass) == DNS_QCLASS_IN)
-					{
-						if (qtype == DNS_QTYPE_A && anlen == 4)
 					{
 						qse_nwad_t nwad;
 
+						nwad.type = QSE_NWAD_NX;
+
+						if (qtype == DNS_QTYPE_A && anlen == 4)
+						{
 							QSE_MEMSET (&nwad, 0, QSE_SIZEOF(nwad));
 							nwad.type = QSE_NWAD_IN4;
 							QSE_MEMCPY (&nwad.u.in4.addr, antrail + 1, 4);
 printf ("invoking resoll with ipv4 \n");
-							req->resol (httpd, req->name, &nwad, req->ctx);
-
-							/* delete the request from dc */
-							if (preq) preq->next = req->next;
-							else dc->reqs[xid] = req->next;
-							qse_httpd_freemem (httpd, req);
-
-							goto done;
 						}
-						else if (qtype == DNS_QTYPE_AAAA || anlen == 16)
+						else if (qtype == DNS_QTYPE_AAAA && anlen == 16)
 						{
-							qse_nwad_t nwad;
-
 							QSE_MEMSET (&nwad, 0, QSE_SIZEOF(nwad));
 							nwad.type = QSE_NWAD_IN6;
 							QSE_MEMCPY (&nwad.u.in6.addr, antrail + 1, 16);
 printf ("invoking resoll with ipv6 \n");
+
+						}
+
+						if (nwad.type != QSE_NWAD_NX)
+						{
 							req->resol (httpd, req->name, &nwad, req->ctx);
 
-							/* delete the request from dc */
+							/* detach the request off dc->reqs */
 							if (preq) preq->next = req->next;
 							else dc->reqs[xid] = req->next;
-							qse_httpd_freemem (httpd, req);
+
+							/*qse_httpd_freemem (httpd, req);*/
+							dns_cache_answer (dc, req, &nwad, qse_ntoh32(antrail->ttl));
 
 							goto done;
 						}
@@ -2445,23 +2579,25 @@ printf ("invoking resoll with ipv6 \n");
 					pllen -= reclen;
 				}
 			}
-			else
+
-			{
+
+			/* no good answer have been found */
 			if (id == req->seqa) req->flags |= DNS_REQ_A_NX;
 			else if (id == req->seqaaaa) req->flags |= DNS_REQ_AAAA_NX;
 
 			if ((req->flags & (DNS_REQ_A_NX | DNS_REQ_AAAA_NX)) == (DNS_REQ_A_NX | DNS_REQ_AAAA_NX))
 			{
+				/* both ipv4 and ipv6 address are unresolvable */
+
 				req->resol (httpd, req->name, QSE_NULL, req->ctx);
 
-					/* delete the request from dc */
+				/* detach the request off dc->reqs */
 				if (preq) preq->next = req->next;
 				else dc->reqs[xid] = req->next;
-					qse_httpd_freemem (httpd, req);
-				}
-			}
 
-			/*req->resol (httpd, req->name, QSE_NULL, req->ctx);*//* TODO: handle this better */
+				/*qse_httpd_freemem (httpd, req);*/
+				dns_cache_answer (dc, req, QSE_NULL, DNS_MIN_TTL);
+			}
 		}
 		
 	}
@@ -2476,7 +2612,18 @@ static int dns_send (qse_httpd_t* httpd, qse_httpd_dns_t* dns, const qse_mchar_t
 	dns_ctx_t* dc = (dns_ctx_t*)dns->ctx;
 	dns_req_t* req;
 	qse_size_t name_len;
+	dns_ans_t* ans;
 
+printf ("finding answer in cache...\n");
+	ans = dns_get_answer_from_cache (dc, name);
+	if (ans)
+	{
+printf ("found answer in cache...\n");
+		resol (httpd, name, ((ans->nwad.type == QSE_NWAD_NX)? QSE_NULL: &ans->nwad), ctx);
+		return 0;
+	}
+
+printf ("found XXXXX in cache...\n");
 	seq = dc->seq;
 	seq = (seq + 1) % QSE_COUNTOF(dc->reqs);
 	dc->seq = seq;
@@ -3169,7 +3316,6 @@ static int make_resource (
 		return 0;
 	}
 
-
 	/* htrd compacts double slashes to a single slash.
 	 * so inspect if the query path begins with http:/ instead of http:// */
 	/*if (qse_mbszcasecmp (tmp.qpath, QSE_MT("http://"), 7) == 0)*/
@@ -3190,6 +3336,7 @@ static int make_resource (
 				if (qse_mbsntonwad (host, slash - host, &target->u.proxy.dst.nwad) <= -1) 
 				{
 /* TODO: refrain from manipulating the request like this */
+
 					QSE_MEMMOVE (host - 1, host, slash - host); 
 					slash[-1] = QSE_MT('\0');
 

qse/lib/http/httpd.c

@@ -904,7 +904,7 @@ static int update_mux_for_current_task (qse_httpd_t* httpd, qse_httpd_client_t*
 
 	clear_trigger_mask_result (task);
 
-printf ("update_mux_for_current_task..............\n");
+/*printf ("update_mux_for_current_task..............\n");*/
 	if (QSE_MEMCMP (&client->trigger, &task->trigger, QSE_SIZEOF(client->trigger)) != 0 ||
 	    ((client->status & CLIENT_MUTE) && !(client->status & CLIENT_MUTE_DELETED)))
 	{
@@ -1070,7 +1070,7 @@ static int update_mux_for_next_task (qse_httpd_t* httpd, qse_httpd_client_t* cli
 	int expected_mux_status;
 	int expected_trigger_cmask;
 
-printf ("update_mux_for_next_task\n");
+/*printf ("update_mux_for_next_task\n");*/
 	expected_mux_mask = QSE_HTTPD_MUX_READ;
 	expected_mux_status = CLIENT_HANDLE_READ_IN_MUX;
 	expected_trigger_cmask = QSE_HTTPD_TASK_TRIGGER_READ;
@@ -1422,7 +1422,6 @@ int qse_httpd_loop (qse_httpd_t* httpd)
 		if (httpd->opt.trait & QSE_HTTPD_LOGACT)
 		{
 			qse_httpd_act_t msg;
-			qse_size_t len;
 			msg.code = QSE_HTTPD_CATCH_MWARNMSG;
 			qse_mbscpy (msg.u.mwarnmsg, QSE_MT("cannot activate dns"));
 			httpd->opt.rcb.logact (httpd, &msg);
@@ -1601,7 +1600,7 @@ int qse_httpd_resolname (qse_httpd_t* httpd, const qse_mchar_t* name, qse_httpd_
 	/* TODO: find the name in cache */
 
 	/* not found in the cache */
-printf ("dns_send.........................\n");
+printf ("DNS_SEND.........................\n");
 	if (!httpd->dnsactive) 
 	{
 		qse_httpd_seterrnum (httpd, QSE_HTTPD_ENODNS);
@@ -1615,11 +1614,9 @@ int qse_httpd_activatetasktrigger (qse_httpd_t* httpd, qse_httpd_client_t* clien
 {
 	int x, org_cmask;
 
-printf ("activate ..$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$..\n");
 	/* don't do anything if it's active */
 	if (!(task->trigger.flags & QSE_HTTPD_TASK_TRIGGER_INACTIVE)) return 0;
 
-printf ("activate reakly....\n");
 	/* when task trigger is inactive, no handle are registered
 	 * into mux. update_mux_for_current_task adds the client handle
 	 * to mux for reading only if writing is not requested explicitly.