fixes #1311 reduce wasted use for nni_aio

fixes #1317 IPv6 listener get port is incorrect
fixes #1319 Want symbolic service names

This is phase 1 of reducing the memory foot-print of aios, and
also of pipes.  This removes the largest consumer the socket
address information, from the aio, which was only used by a few
consumers.

10 files changed, 187 insertions, 277 deletions

diff --git a/src/core/aio.c b/src/core/aio.c
index 97bb9153..6a390677 100644
--- a/src/core/aio.c
+++ b/src/core/aio.c
@@ -699,15 +699,3 @@ nni_aio_sys_init(void)
 	nni_thr_run(thr);
 	return (0);
 }
-
-void
-nni_aio_set_sockaddr(nni_aio *aio, const nng_sockaddr *sa)
-{
-	memcpy(&aio->a_sockaddr, sa, sizeof(*sa));
-}
-
-void
-nni_aio_get_sockaddr(nni_aio *aio, nng_sockaddr *sa)
-{
-	memcpy(sa, &aio->a_sockaddr, sizeof(*sa));
-}
\ No newline at end of file
diff --git a/src/core/aio.h b/src/core/aio.h
index c2776bc0..2f699245 100644
--- a/src/core/aio.h
+++ b/src/core/aio.h
@@ -155,12 +155,9 @@ extern void nni_aio_get_iov(nni_aio *, unsigned *, nni_iov **);
 extern void nni_aio_normalize_timeout(nni_aio *, nng_duration);
 extern void nni_aio_bump_count(nni_aio *, size_t);
 
-extern void nni_aio_set_sockaddr(nni_aio *aio, const nng_sockaddr *);
-extern void nni_aio_get_sockaddr(nni_aio *aio, nng_sockaddr *);
-
 // nni_aio_schedule indicates that the AIO has begun, and is scheduled for
-// asychronous completion. This also starts the expiration timer. Note that
-// prior to this, the aio is uncancellable.  If the operation has a zero
+// asynchronous completion. This also starts the expiration timer. Note that
+// prior to this, the aio cannot be canceled.  If the operation has a zero
 // timeout (NNG_FLAG_NONBLOCK) then NNG_ETIMEDOUT is returned.  If the
 // operation has already been canceled, or should not be run, then an error
 // is returned.  (In that case the caller should probably either return an
@@ -198,7 +195,7 @@ struct nng_aio {
 
 	// User scratch data.  Consumers may store values here, which
 	// must be preserved by providers and the framework.
-	void *a_user_data[4];
+	void *a_user_data[2];
 
 	// Operation inputs & outputs.  Up to 4 inputs and 4 outputs may be
 	// specified.  The semantics of these will vary, and depend on the
@@ -210,13 +207,7 @@ struct nng_aio {
 	nni_aio_cancelfn a_cancel_fn;
 	void *           a_cancel_arg;
 	nni_list_node    a_prov_node;     // Linkage on provider list.
-	void *           a_prov_extra[4]; // Extra data used by provider
-
-	// Socket address.  This turns out to be very useful, as we wind up
-	// needing socket addresses for numerous connection related routines.
-	// It would be cleaner to not have this and avoid burning the space,
-	// but having this hear dramatically simplifies lots of code.
-	nng_sockaddr a_sockaddr;
+	void *           a_prov_extra[2]; // Extra data used by provider
 
 	// Expire node.
 	nni_list_node a_expire_node;
diff --git a/src/core/platform.h b/src/core/platform.h
index 6eff2f7d..704e338d 100644
--- a/src/core/platform.h
+++ b/src/core/platform.h
@@ -287,7 +287,7 @@ extern void nni_tcp_dialer_close(nni_tcp_dialer *);
 // nni_tcp_dial attempts to create an outgoing connection,
 // asynchronously, to the address in the aio. On success, the first (and only)
 // output will be an nni_tcp_conn * associated with the remote server.
-extern void nni_tcp_dial(nni_tcp_dialer *, nni_aio *);
+extern void nni_tcp_dial(nni_tcp_dialer *, const nng_sockaddr *, nni_aio *);
 
 // nni_tcp_dialer_getopt gets an option from the dialer.
 extern int nni_tcp_dialer_setopt(
@@ -331,17 +331,16 @@ extern int nni_tcp_listener_setopt(
 extern int nni_tcp_listener_getopt(
     nni_tcp_listener *, const char *, void *, size_t *, nni_type);
 
-// nni_tcp_resolv resolves a TCP name asynchronously.  The family
-// should be one of NNG_AF_INET, NNG_AF_INET6, or NNG_AF_UNSPEC.  The
-// first two constrain the name to those families, while the third will
+// nni_resolv_ip resolves a DNS host and service name asynchronously.
+// The family should be one of NNG_AF_INET, NNG_AF_INET6, or NNG_AF_UNSPEC.
+// The first two constrain the name to those families, while the third will
 // return names of either family.  The passive flag indicates that the
 // name will be used for bind(), otherwise the name will be used with
 // connect().  The host part may be NULL only if passive is true.
-extern void nni_tcp_resolv(const char *, const char *, int, int, nni_aio *);
-
-// nni_udp_resolv is just like nni_tcp_resolv, but looks up
-// service names using UDP.
-extern void nni_udp_resolv(const char *, const char *, int, int, nni_aio *);
+// Symbolic service names will be looked up assuming SOCK_STREAM, so
+// they may not work with UDP.
+extern void nni_resolv_ip(const char *, const char *, int, bool,
+    nng_sockaddr *sa, nni_aio *);
 
 // nni_parse_ip parses an IP address, without a port.
 extern int nni_parse_ip(const char *, nng_sockaddr *);
diff --git a/src/platform/posix/posix_resolv_gai.c b/src/platform/posix/posix_resolv_gai.c
index c6732a12..888cc9b7 100644
--- a/src/platform/posix/posix_resolv_gai.c
+++ b/src/platform/posix/posix_resolv_gai.c
@@ -16,6 +16,7 @@
 #include <errno.h>
 #include <netdb.h>
 #include <netinet/in.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/un.h>
@@ -40,18 +41,23 @@ static nni_thr  resolv_thrs[NNG_RESOLV_CONCURRENCY];
 
 typedef struct resolv_item resolv_item;
 struct resolv_item {
-	int          family;
-	int          passive;
-	char         name_buf[256];
-	char *       name;
-	int          proto;
-	int          socktype;
-	uint16_t     port;
-	nni_aio *    aio;
-	nng_sockaddr sa;
+	int           family;
+	bool          passive;
+	char *        host;
+	char *        serv;
+	nni_aio *     aio;
+	nng_sockaddr *sa;
 };
 
 static void
+resolv_free_item(resolv_item *item)
+{
+	nni_strfree(item->serv);
+	nni_strfree(item->host);
+	NNI_FREE_STRUCT(item);
+}
+
+static void
 resolv_cancel(nni_aio *aio, void *arg, int rv)
 {
 	resolv_item *item = arg;
@@ -68,13 +74,14 @@ resolv_cancel(nni_aio *aio, void *arg, int rv)
 		// so we can just discard everything.
 		nni_aio_list_remove(aio);
 		nni_mtx_unlock(&resolv_mtx);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 	} else {
 		// This case indicates the resolver is still processing our
 		// node. We can discard our interest in the result, but we
 		// can't interrupt the resolver itself.  (Too bad, name
 		// resolution is utterly synchronous for now.)
 		item->aio = NULL;
+		item->sa  = NULL;
 		nni_mtx_unlock(&resolv_mtx);
 	}
 	nni_aio_finish_error(aio, rv);
@@ -135,20 +142,36 @@ resolv_task(resolv_item *item)
 	// host part are split.
 	memset(&hints, 0, sizeof(hints));
 #ifdef AI_ADDRCONFIG
-	hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
-#else
-	hints.ai_flags = AI_NUMERICSERV;
+	hints.ai_flags = AI_ADDRCONFIG;
 #endif
 	if (item->passive) {
 		hints.ai_flags |= AI_PASSIVE;
 	}
-	hints.ai_protocol = item->proto;
 	hints.ai_family   = item->family;
-	hints.ai_socktype = item->socktype;
+	hints.ai_socktype = SOCK_STREAM;
+
+	// Check to see if this is a numeric port number, and if it is
+	// make sure that it's in the valid range (because Windows may
+	// incorrectly simple do a conversion and mask off upper bits.
+	if (item->serv != NULL) {
+		long  port;
+		char *end;
+		port = strtol(item->serv, &end, 10);
+		if (*end == '\0') { // we fully converted it as a number...
+			hints.ai_flags |= AI_NUMERICSERV;
+
+			// Not a valid port number.  Fail.
+			if ((port < 0) || (port > 0xffff)) {
+				rv = NNG_EADDRINVAL;
+				goto done;
+			}
+		}
+	}
 
 	// We can pass any non-zero service number, but we have to pass
 	// *something*, in case we are using a NULL hostname.
-	if ((rv = getaddrinfo(item->name, "80", &hints, &results)) != 0) {
+	if ((rv = getaddrinfo(item->host, item->serv, &hints, &results)) !=
+	    0) {
 		rv = posix_gai_errno(rv);
 		goto done;
 	}
@@ -164,29 +187,31 @@ resolv_task(resolv_item *item)
 		}
 	}
 
-	if (probe != NULL) {
+	nni_mtx_lock(&resolv_mtx);
+	if ((probe != NULL) && (item->aio != NULL)) {
 		struct sockaddr_in * sin;
 		struct sockaddr_in6 *sin6;
-		nng_sockaddr *       sa = &item->sa;
+		nng_sockaddr *       sa = item->sa;
 
 		switch (probe->ai_addr->sa_family) {
 		case AF_INET:
 			rv                 = 0;
 			sin                = (void *) probe->ai_addr;
 			sa->s_in.sa_family = NNG_AF_INET;
-			sa->s_in.sa_port   = item->port;
+			sa->s_in.sa_port   = sin->sin_port;
 			sa->s_in.sa_addr   = sin->sin_addr.s_addr;
 			break;
 		case AF_INET6:
 			rv                  = 0;
 			sin6                = (void *) probe->ai_addr;
 			sa->s_in6.sa_family = NNG_AF_INET6;
-			sa->s_in6.sa_port   = item->port;
+			sa->s_in6.sa_port   = sin6->sin6_port;
 			sa->s_in6.sa_scope  = sin6->sin6_scope_id;
 			memcpy(sa->s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
 			break;
 		}
 	}
+	nni_mtx_unlock(&resolv_mtx);
 
 done:
 
@@ -197,19 +222,18 @@ done:
 	return (rv);
 }
 
-static void
-resolv_ip(const char *host, const char *serv, int passive, int family,
-    int proto, int socktype, nni_aio *aio)
+void
+nni_resolv_ip(const char *host, const char *serv, int af, bool passive,
+    nng_sockaddr *sa, nni_aio *aio)
 {
 	resolv_item *item;
 	sa_family_t  fam;
 	int          rv;
-	int          port;
 
 	if (nni_aio_begin(aio) != 0) {
 		return;
 	}
-	switch (family) {
+	switch (af) {
 	case NNG_AF_INET:
 		fam = AF_INET;
 		break;
@@ -224,62 +248,30 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 		return;
 	}
 
-	// We can't use the resolver to look up up ports with AI_NUMERICSERV,
-	// because some resolver(s) is(are?) broken.  For example, the
-	// systemd resolver takes a port number of 1000000 and just rips off
-	// the high order bits and lets it through!
-	port = 0;
-	if (serv != NULL) {
-		while (isdigit(*serv)) {
-			port *= 10;
-			port += (*serv - '0');
-			if (port > 0xffff) {
-				// Port number out of range.
-				nni_aio_finish_error(aio, NNG_EADDRINVAL);
-				return;
-			}
-			serv++;
-		}
-		if (*serv != '\0') {
-			nni_aio_finish_error(aio, NNG_EADDRINVAL);
-			return;
-		}
-	}
-	if ((port == 0) && (!passive)) {
-		nni_aio_finish_error(aio, NNG_EADDRINVAL);
-		return;
-	}
-
 	if ((item = NNI_ALLOC_STRUCT(item)) == NULL) {
 		nni_aio_finish_error(aio, NNG_ENOMEM);
 		return;
 	}
 
-	// NB: must remain valid until this is completed.  So we have to
-	// keep our own copy.
-
-	if (host != NULL &&
-	    nni_strnlen(host, sizeof(item->name_buf)) >=
-	        sizeof(item->name_buf)) {
-		NNI_FREE_STRUCT(item);
-		nni_aio_finish_error(aio, NNG_EADDRINVAL);
+	if (serv == NULL) {
+		item->serv = NULL;
+	} else if ((item->serv = nni_strdup(serv)) == NULL) {
+		nni_aio_finish_error(aio, NNG_ENOMEM);
+		resolv_free_item(item);
 		return;
 	}
-
 	if (host == NULL) {
-		item->name = NULL;
-	} else {
-		nni_strlcpy(item->name_buf, host, sizeof(item->name_buf));
-		item->name = item->name_buf;
+		item->host = NULL;
+	} else if ((item->host = nni_strdup(host)) == NULL) {
+		nni_aio_finish_error(aio, NNG_ENOMEM);
+		resolv_free_item(item);
+		return;
 	}
 
-	memset(&item->sa, 0, sizeof(item->sa));
-	item->proto    = proto;
-	item->aio      = aio;
-	item->family   = fam;
-	item->passive  = passive;
-	item->socktype = socktype;
-	item->port     = htons((uint16_t) port);
+	item->aio     = aio;
+	item->family  = fam;
+	item->passive = passive;
+	item->sa      = sa;
 
 	nni_mtx_lock(&resolv_mtx);
 	if (resolv_fini) {
@@ -290,7 +282,7 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 	}
 	if (rv != 0) {
 		nni_mtx_unlock(&resolv_mtx);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 		nni_aio_finish_error(aio, rv);
 		return;
 	}
@@ -300,20 +292,6 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 }
 
 void
-nni_tcp_resolv(
-    const char *host, const char *serv, int family, int passive, nni_aio *aio)
-{
-	resolv_ip(host, serv, passive, family, IPPROTO_TCP, SOCK_STREAM, aio);
-}
-
-void
-nni_udp_resolv(
-    const char *host, const char *serv, int family, int passive, nni_aio *aio)
-{
-	resolv_ip(host, serv, passive, family, IPPROTO_UDP, SOCK_DGRAM, aio);
-}
-
-void
 resolv_worker(void *unused)
 {
 
@@ -348,11 +326,11 @@ resolv_worker(void *unused)
 
 			nni_aio_set_prov_extra(aio, 0, NULL);
 			item->aio = NULL;
+			item->sa  = NULL;
 
-			nni_aio_set_sockaddr(aio, &item->sa);
 			nni_aio_finish(aio, rv, 0);
 		}
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 	}
 	nni_mtx_unlock(&resolv_mtx);
 }
diff --git a/src/platform/posix/posix_tcpdial.c b/src/platform/posix/posix_tcpdial.c
index 3fabc28a..9b3a91f5 100644
--- a/src/platform/posix/posix_tcpdial.c
+++ b/src/platform/posix/posix_tcpdial.c
@@ -169,7 +169,7 @@ tcp_dialer_cb(nni_posix_pfd *pfd, unsigned ev, void *arg)
 // We don't give local address binding support.  Outbound dialers always
 // get an ephemeral port.
 void
-nni_tcp_dial(nni_tcp_dialer *d, nni_aio *aio)
+nni_tcp_dial(nni_tcp_dialer *d, const nni_sockaddr *sa, nni_aio *aio)
 {
 	nni_tcp_conn *          c;
 	nni_posix_pfd *         pfd = NULL;
@@ -179,14 +179,12 @@ nni_tcp_dial(nni_tcp_dialer *d, nni_aio *aio)
 	int                     rv;
 	int                     ka;
 	int                     nd;
-	nng_sockaddr            sa;
 
 	if (nni_aio_begin(aio) != 0) {
 		return;
 	}
 
-	nni_aio_get_sockaddr(aio, &sa);
-	if (((sslen = nni_posix_nn2sockaddr(&ss, &sa)) == 0) ||
+	if (((sslen = nni_posix_nn2sockaddr(&ss, sa)) == 0) ||
 	    ((ss.ss_family != AF_INET) && (ss.ss_family != AF_INET6))) {
 		nni_aio_finish_error(aio, NNG_EADDRINVAL);
 		return;
diff --git a/src/platform/windows/win_resolv.c b/src/platform/windows/win_resolv.c
index d810ecac..8628719f 100644
--- a/src/platform/windows/win_resolv.c
+++ b/src/platform/windows/win_resolv.c
@@ -11,7 +11,7 @@
 #include "core/nng_impl.h"
 
 #include <ctype.h>
-#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #ifdef NNG_PLATFORM_WINDOWS
@@ -34,17 +34,23 @@ static nni_thr  resolv_thrs[NNG_RESOLV_CONCURRENCY];
 
 typedef struct resolv_item resolv_item;
 struct resolv_item {
-	int          family;
-	int          passive;
-	char *       name;
-	int          proto;
-	int          socktype;
-	uint16_t     port;
-	nni_aio *    aio;
-	nng_sockaddr sa;
+	int           family;
+	bool          passive;
+	char *        host;
+	char *        serv;
+	nni_aio *     aio;
+	nng_sockaddr *sa;
 };
 
 static void
+resolv_free_item(resolv_item *item)
+{
+	nni_strfree(item->serv);
+	nni_strfree(item->host);
+	NNI_FREE_STRUCT(item);
+}
+
+static void
 resolv_cancel(nni_aio *aio, void *arg, int rv)
 {
 	resolv_item *item = arg;
@@ -60,12 +66,12 @@ resolv_cancel(nni_aio *aio, void *arg, int rv)
 		// so we can just discard everything.
 		nni_aio_list_remove(aio);
 		nni_mtx_unlock(&resolv_mtx);
-		nni_strfree(item->name);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 	} else {
 		// Resolver still working, so just unlink our AIO to
 		// discard our interest in the results.
 		item->aio = NULL;
+		item->sa  = NULL;
 		nni_mtx_unlock(&resolv_mtx);
 	}
 	nni_aio_finish_error(aio, rv);
@@ -108,18 +114,34 @@ resolv_task(resolv_item *item)
 
 	results = NULL;
 
-	// We treat these all as IP addresses.  The service and the
-	// host part are split.
 	memset(&hints, 0, sizeof(hints));
-	hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
+	hints.ai_flags = AI_ADDRCONFIG;
 	if (item->passive) {
 		hints.ai_flags |= AI_PASSIVE;
 	}
-	hints.ai_protocol = item->proto;
 	hints.ai_family   = item->family;
-	hints.ai_socktype = item->socktype;
+	hints.ai_socktype = SOCK_STREAM;
+
+	// Check to see if this is a numeric port number, and if it is
+	// make sure that it's in the valid range (because Windows may
+	// incorrectly simple do a conversion and mask off upper bits.
+	if (item->serv != NULL) {
+		long  port;
+		char *end;
+		port = strtol(item->serv, &end, 10);
+		if (*end == '\0') { // we fully converted it as a number...
+			hints.ai_flags |= AI_NUMERICSERV;
+
+			// Not a valid port number.  Fail.
+			if ((port < 0) || (port > 0xffff)) {
+				rv = NNG_EADDRINVAL;
+				goto done;
+			}
+		}
+	}
 
-	if ((rv = getaddrinfo(item->name, "80", &hints, &results)) != 0) {
+	if ((rv = getaddrinfo(item->host, item->serv, &hints, &results)) !=
+	    0) {
 		rv = resolv_errno(rv);
 		goto done;
 	}
@@ -135,31 +157,33 @@ resolv_task(resolv_item *item)
 		}
 	}
 
+	nni_mtx_lock(&resolv_mtx);
 	if ((probe != NULL) && (item->aio != NULL)) {
 		struct sockaddr_in * sin;
 		struct sockaddr_in6 *sin6;
-		nni_sockaddr         sa;
+		nni_sockaddr *       sa;
+
+		sa = item->sa;
 
 		switch (probe->ai_addr->sa_family) {
 		case AF_INET:
-			rv                = 0;
-			sin               = (void *) probe->ai_addr;
-			sa.s_in.sa_family = NNG_AF_INET;
-			sa.s_in.sa_port   = item->port;
-			sa.s_in.sa_addr   = sin->sin_addr.s_addr;
-			nni_aio_set_sockaddr(item->aio, &sa);
+			rv                 = 0;
+			sin                = (void *) probe->ai_addr;
+			sa->s_in.sa_family = NNG_AF_INET;
+			sa->s_in.sa_port   = sin->sin_port;
+			sa->s_in.sa_addr   = sin->sin_addr.s_addr;
 			break;
 		case AF_INET6:
-			rv                 = 0;
-			sin6               = (void *) probe->ai_addr;
-			sa.s_in6.sa_family = NNG_AF_INET6;
-			sa.s_in6.sa_port   = item->port;
-			sa.s_in6.sa_scope  = sin6->sin6_scope_id;
-			memcpy(sa.s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
-			nni_aio_set_sockaddr(item->aio, &sa);
+			rv                  = 0;
+			sin6                = (void *) probe->ai_addr;
+			sa->s_in6.sa_family = NNG_AF_INET6;
+			sa->s_in6.sa_port   = sin6->sin6_port;
+			sa->s_in6.sa_scope  = sin6->sin6_scope_id;
+			memcpy(sa->s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
 			break;
 		}
 	}
+	nni_mtx_unlock(&resolv_mtx);
 
 done:
 
@@ -169,14 +193,13 @@ done:
 	return (rv);
 }
 
-static void
-resolv_ip(const char *host, const char *serv, int passive, int family,
-    int proto, int socktype, nni_aio *aio)
+void
+nni_resolv_ip(const char *host, const char *serv, int family, bool passive,
+    nng_sockaddr *sa, nni_aio *aio)
 {
 	resolv_item *item;
 	int          fam;
 	int          rv;
-	int          port;
 
 	if (nni_aio_begin(aio) != 0) {
 		return;
@@ -196,52 +219,30 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 		return;
 	}
 
-	// We can't use the resolver to look up up ports with AI_NUMERICSERV,
-	// because Windows' resolver is broken.  For example, the resolver
-	// takes a port number of 1000000 and just rips off the high order
-	// bits and lets it through!  (It seems to time out though, so
-	// maybe it is ignoring AI_NUMERICSERV.)
-	port = 0;
-	if (serv != NULL) {
-		while (isdigit(*serv)) {
-			port *= 10;
-			port += (*serv - '0');
-			if (port > 0xffff) {
-				// Port number out of range.
-				nni_aio_finish_error(aio, NNG_EADDRINVAL);
-				return;
-			}
-			serv++;
-		}
-		if (*serv != '\0') {
-			nni_aio_finish_error(aio, NNG_EADDRINVAL);
-			return;
-		}
-	}
-	if ((port == 0) && (!passive)) {
-		nni_aio_finish_error(aio, NNG_EADDRINVAL);
-		return;
-	}
-
 	if ((item = NNI_ALLOC_STRUCT(item)) == NULL) {
 		nni_aio_finish_error(aio, NNG_ENOMEM);
 		return;
 	}
 	if (host == NULL) {
-		item->name = NULL;
-	} else if ((item->name = nni_strdup(host)) == NULL) {
+		item->host = NULL;
+	} else if ((item->host = nni_strdup(host)) == NULL) {
+		nni_aio_finish_error(aio, NNG_ENOMEM);
+		resolv_free_item(item);
+		return;
+	}
+
+	if (serv == NULL) {
+		item->serv = NULL;
+	} else if ((item->serv = nni_strdup(serv)) == NULL) {
 		nni_aio_finish_error(aio, NNG_ENOMEM);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 		return;
 	}
 
-	memset(&item->sa, 0, sizeof(item->sa));
-	item->passive  = passive;
-	item->proto    = proto;
-	item->aio      = aio;
-	item->family   = fam;
-	item->socktype = socktype;
-	item->port     = htons((uint16_t) port);
+	item->sa      = sa;
+	item->passive = passive;
+	item->aio     = aio;
+	item->family  = fam;
 
 	nni_mtx_lock(&resolv_mtx);
 	if (resolv_fini) {
@@ -252,8 +253,7 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 	}
 	if (rv != 0) {
 		nni_mtx_unlock(&resolv_mtx);
-		nni_strfree(item->name);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 		nni_aio_finish_error(aio, rv);
 		return;
 	}
@@ -263,20 +263,6 @@ resolv_ip(const char *host, const char *serv, int passive, int family,
 }
 
 void
-nni_tcp_resolv(
-    const char *host, const char *serv, int family, int passive, nni_aio *aio)
-{
-	resolv_ip(host, serv, passive, family, IPPROTO_TCP, SOCK_STREAM, aio);
-}
-
-void
-nni_udp_resolv(
-    const char *host, const char *serv, int family, int passive, nni_aio *aio)
-{
-	resolv_ip(host, serv, passive, family, IPPROTO_UDP, SOCK_DGRAM, aio);
-}
-
-void
 resolv_worker(void *notused)
 {
 
@@ -308,11 +294,11 @@ resolv_worker(void *notused)
 		if ((aio = item->aio) != NULL) {
 			nni_aio_set_prov_extra(aio, 0, NULL);
 			item->aio = NULL;
+			item->sa  = NULL;
 
 			nni_aio_finish(aio, rv, 0);
 		}
-		nni_strfree(item->name);
-		NNI_FREE_STRUCT(item);
+		resolv_free_item(item);
 	}
 	nni_mtx_unlock(&resolv_mtx);
 }
diff --git a/src/platform/windows/win_tcpdial.c b/src/platform/windows/win_tcpdial.c
index 3d470ca1..89c5bf6a 100644
--- a/src/platform/windows/win_tcpdial.c
+++ b/src/platform/windows/win_tcpdial.c
@@ -173,22 +173,19 @@ tcp_dial_cb(nni_win_io *io, int rv, size_t cnt)
 }
 
 void
-nni_tcp_dial(nni_tcp_dialer *d, nni_aio *aio)
+nni_tcp_dial(nni_tcp_dialer *d, const nni_sockaddr *sa, nni_aio *aio)
 {
 	SOCKET           s;
 	SOCKADDR_STORAGE ss;
 	int              len;
 	nni_tcp_conn *   c;
 	int              rv;
-	nng_sockaddr     sa;
-
-	nni_aio_get_sockaddr(aio, &sa);
 
 	if (nni_aio_begin(aio) != 0) {
 		return;
 	}
 
-	if ((len = nni_win_nn2sockaddr(&ss, &sa)) <= 0) {
+	if ((len = nni_win_nn2sockaddr(&ss, sa)) <= 0) {
 		nni_aio_finish_error(aio, NNG_EADDRINVAL);
 		return;
 	}
diff --git a/src/supplemental/tcp/tcp.c b/src/supplemental/tcp/tcp.c
index 2fb7f56d..cde79051 100644
--- a/src/supplemental/tcp/tcp.c
+++ b/src/supplemental/tcp/tcp.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2019 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2019 Devolutions <info@devolutions.net>
 //
@@ -9,7 +9,6 @@
 // found online at https://opensource.org/licenses/MIT.
 //
 
-#include <stddef.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -28,7 +27,6 @@ typedef struct {
 	nni_tcp_dialer *  d;      // platform dialer implementation
 	nni_aio *         resaio; // resolver aio
 	nni_aio *         conaio; // platform connection aio
-	nni_list          resaios;
 	nni_list          conaios;
 	nni_mtx           mtx;
 } tcp_dialer;
@@ -45,8 +43,6 @@ tcp_dial_cancel(nni_aio *aio, void *arg, int rv)
 
 		if (nni_list_empty(&d->conaios)) {
 			nni_aio_abort(d->conaio, NNG_ECANCELED);
-		}
-		if (nni_list_empty(&d->resaios)) {
 			nni_aio_abort(d->resaio, NNG_ECANCELED);
 		}
 	}
@@ -54,6 +50,15 @@ tcp_dial_cancel(nni_aio *aio, void *arg, int rv)
 }
 
 static void
+tcp_dial_start_next(tcp_dialer *d)
+{
+	if (nni_list_empty(&d->conaios)) {
+		return;
+	}
+	nni_resolv_ip(d->host, d->port, d->af, false, &d->sa, d->resaio);
+}
+
+static void
 tcp_dial_res_cb(void *arg)
 {
 	tcp_dialer *d = arg;
@@ -61,34 +66,27 @@ tcp_dial_res_cb(void *arg)
 	int         rv;
 
 	nni_mtx_lock(&d->mtx);
-	if (d->closed || ((aio = nni_list_first(&d->resaios)) == NULL)) {
+	if (d->closed || ((aio = nni_list_first(&d->conaios)) == NULL)) {
 		// ignore this.
-		while ((aio = nni_list_first(&d->resaios)) != NULL) {
-			nni_list_remove(&d->resaios, aio);
+		while ((aio = nni_list_first(&d->conaios)) != NULL) {
+			nni_list_remove(&d->conaios, aio);
 			nni_aio_finish_error(aio, NNG_ECLOSED);
 		}
 		nni_mtx_unlock(&d->mtx);
 		return;
 	}
 
-	nni_list_remove(&d->resaios, aio);
-
 	if ((rv = nni_aio_result(d->resaio)) != 0) {
+		nni_list_remove(&d->conaios, aio);
 		nni_aio_finish_error(aio, rv);
+
+		// try DNS again for next connection...
+		tcp_dial_start_next(d);
+
 	} else {
-		nng_sockaddr sa;
-		nni_aio_get_sockaddr(d->resaio, &sa);
-		nni_aio_set_sockaddr(aio, &sa);
-		nni_list_append(&d->conaios, aio);
-		if (nni_list_first(&d->conaios) == aio) {
-			nni_aio_set_sockaddr(d->conaio, &sa);
-			nni_tcp_dial(d->d, d->conaio);
-		}
+		nni_tcp_dial(d->d, &d->sa, d->conaio);
 	}
 
-	if (!nni_list_empty(&d->resaios)) {
-		nni_tcp_resolv(d->host, d->port, d->af, 0, d->resaio);
-	}
 	nni_mtx_unlock(&d->mtx);
 }
 
@@ -118,12 +116,7 @@ tcp_dial_con_cb(void *arg)
 		nni_aio_finish(aio, 0, 0);
 	}
 
-	if ((aio = nni_list_first(&d->conaios)) != NULL) {
-		nng_sockaddr sa;
-		nni_aio_get_sockaddr(aio, &sa);
-		nni_aio_set_sockaddr(d->conaio, &sa);
-		nni_tcp_dial(d->d, d->conaio);
-	}
+	tcp_dial_start_next(d);
 	nni_mtx_unlock(&d->mtx);
 }
 
@@ -134,10 +127,6 @@ tcp_dialer_close(void *arg)
 	nni_aio *   aio;
 	nni_mtx_lock(&d->mtx);
 	d->closed = true;
-	while ((aio = nni_list_first(&d->resaios)) != NULL) {
-		nni_list_remove(&d->resaios, aio);
-		nni_aio_finish_error(aio, NNG_ECLOSED);
-	}
 	while ((aio = nni_list_first(&d->conaios)) != NULL) {
 		nni_list_remove(&d->conaios, aio);
 		nni_aio_finish_error(aio, NNG_ECLOSED);
@@ -189,17 +178,9 @@ tcp_dialer_dial(void *arg, nng_aio *aio)
 		nni_aio_finish_error(aio, rv);
 		return;
 	}
-	if (d->host != NULL) {
-		nni_list_append(&d->resaios, aio);
-		if (nni_list_first(&d->resaios) == aio) {
-			nni_tcp_resolv(d->host, d->port, d->af, 0, d->resaio);
-		}
-	} else {
-		nni_list_append(&d->conaios, aio);
-		if (nni_list_first(&d->conaios) == aio) {
-			nni_aio_set_sockaddr(d->conaio, &d->sa);
-			nni_tcp_dial(d->d, d->conaio);
-		}
+	nni_list_append(&d->conaios, aio);
+	if (nni_list_first(&d->conaios) == aio) {
+		tcp_dial_start_next(d);
 	}
 	nni_mtx_unlock(&d->mtx);
 }
@@ -231,7 +212,6 @@ tcp_dialer_alloc(tcp_dialer **dp)
 	}
 
 	nni_mtx_init(&d->mtx);
-	nni_aio_list_init(&d->resaios);
 	nni_aio_list_init(&d->conaios);
 
 	if (((rv = nni_aio_alloc(&d->resaio, tcp_dial_res_cb, d)) != 0) ||
@@ -352,8 +332,9 @@ tcp_listener_get_port(void *arg, void *buf, size_t *szp, nni_type t)
 		break;
 
 	case NNG_AF_INET6:
-		paddr = (void *) &sa.s_in.sa_port;
+		paddr = (void *) &sa.s_in6.sa_port;
 		break;
+
 	default:
 		paddr = NULL;
 		break;
@@ -442,14 +423,13 @@ nni_tcp_listener_alloc(nng_stream_listener **lp, const nng_url *url)
 	if ((h != NULL) && ((strcmp(h, "*") == 0) || (strcmp(h, "") == 0))) {
 		h = NULL;
 	}
-	nni_tcp_resolv(h, url->u_port, af, 1, aio);
+	nni_resolv_ip(h, url->u_port, af, true, &sa, aio);
 	nni_aio_wait(aio);
 
 	if ((rv = nni_aio_result(aio)) != 0) {
 		nni_aio_free(aio);
 		return (rv);
 	}
-	nni_aio_get_sockaddr(aio, &sa);
 	nni_aio_free(aio);
 
 	return (tcp_listener_alloc_addr(lp, &sa));
diff --git a/src/transport/tcp/tcp.c b/src/transport/tcp/tcp.c
index aee917e9..c240f4ef 100644
--- a/src/transport/tcp/tcp.c
+++ b/src/transport/tcp/tcp.c
@@ -728,11 +728,8 @@ tcptran_url_parse_source(nng_url *url, nng_sockaddr *sa, const nng_url *surl)
 		return (rv);
 	}
 
-	nni_tcp_resolv(src, 0, af, 1, aio);
+	nni_resolv_ip(src, "0", af, true, sa, aio);
 	nni_aio_wait(aio);
-	if ((rv = nni_aio_result(aio)) == 0) {
-		nni_aio_get_sockaddr(aio, sa);
-	}
 	nni_aio_free(aio);
 	nni_free(src, len + 1);
 	return (rv);
diff --git a/src/transport/tls/tls.c b/src/transport/tls/tls.c
index c291ecf7..76e182a4 100644
--- a/src/transport/tls/tls.c
+++ b/src/transport/tls/tls.c
@@ -701,11 +701,8 @@ tlstran_url_parse_source(nni_url *url, nng_sockaddr *sa, const nni_url *surl)
 		return (rv);
 	}
 
-	nni_tcp_resolv(src, 0, af, 1, aio);
+	nni_resolv_ip(src, "0", af, 1, sa, aio);
 	nni_aio_wait(aio);
-	if ((rv = nni_aio_result(aio)) == 0) {
-		nni_aio_get_sockaddr(aio, sa);
-	}
 	nni_aio_free(aio);
 	nni_free(src, len + 1);
 	return (rv);
@@ -939,8 +936,7 @@ tlstran_ep_init_listener(void **lp, nni_url *url, nni_listener *nlistener)
 		tlstran_ep_fini(ep);
 		return (rv);
 	}
-	nni_aio_set_input(aio, 0, &ep->sa);
-	nni_tcp_resolv(host, url->u_port, af, 1, aio);
+	nni_resolv_ip(host, url->u_port, af, true, &ep->sa, aio);
 	nni_aio_wait(aio);
 	rv = nni_aio_result(aio);
 	nni_aio_free(aio);