fixes #1496 Provide NNG_ENABLE_IPV6 option (disabled by default)

This also checks if the build system has the definitions for AF_INET6, which might
help in some embedded IPv4 only settings.

The resolver test is enhanced to include a check for IPv6 enabled in the kernel.

IPv6 support is enabled by default, of course.

14 files changed, 329 insertions, 172 deletions

diff --git a/src/core/stream.c b/src/core/stream.c
index 99002fcd..95bc4123 100644
--- a/src/core/stream.c
+++ b/src/core/stream.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 //
 // This software is supplied under the terms of the MIT License, a
 // copy of which should be located in the distribution where this
@@ -22,8 +22,8 @@
 
 static struct {
 	const char *scheme;
-	int (*dialer_alloc)(nng_stream_dialer **, const nng_url *);
-	int (*listener_alloc)(nng_stream_listener **, const nng_url *);
+	int         (*dialer_alloc)(nng_stream_dialer **, const nng_url *);
+	int         (*listener_alloc)(nng_stream_listener **, const nng_url *);
 
 } stream_drivers[] = {
 	{
@@ -55,11 +55,13 @@ static struct {
 	    .dialer_alloc   = nni_tcp_dialer_alloc,
 	    .listener_alloc = nni_tcp_listener_alloc,
 	},
+#ifdef NNG_ENABLE_IPV6
 	{
 	    .scheme         = "tcp6",
 	    .dialer_alloc   = nni_tcp_dialer_alloc,
 	    .listener_alloc = nni_tcp_listener_alloc,
 	},
+#endif
 	{
 	    .scheme         = "tls+tcp",
 	    .dialer_alloc   = nni_tls_dialer_alloc,
@@ -70,11 +72,13 @@ static struct {
 	    .dialer_alloc   = nni_tls_dialer_alloc,
 	    .listener_alloc = nni_tls_listener_alloc,
 	},
+#ifdef NNG_ENABLE_IPV6
 	{
 	    .scheme         = "tls+tcp6",
 	    .dialer_alloc   = nni_tls_dialer_alloc,
 	    .listener_alloc = nni_tls_listener_alloc,
 	},
+#endif
 	{
 	    .scheme         = "ws",
 	    .dialer_alloc   = nni_ws_dialer_alloc,
@@ -85,11 +89,13 @@ static struct {
 	    .dialer_alloc   = nni_ws_dialer_alloc,
 	    .listener_alloc = nni_ws_listener_alloc,
 	},
+#ifdef NNG_ENABLE_IPV6
 	{
 	    .scheme         = "ws6",
 	    .dialer_alloc   = nni_ws_dialer_alloc,
 	    .listener_alloc = nni_ws_listener_alloc,
 	},
+#endif
 	{
 	    .scheme         = "wss",
 	    .dialer_alloc   = nni_ws_dialer_alloc,
diff --git a/src/platform/posix/CMakeLists.txt b/src/platform/posix/CMakeLists.txt
index b8e3782e..a00ffa50 100644
--- a/src/platform/posix/CMakeLists.txt
+++ b/src/platform/posix/CMakeLists.txt
@@ -62,6 +62,7 @@ if (NNG_PLATFORM_POSIX)
     nng_check_sym(getpeerucred ucred.h NNG_HAVE_GETPEERUCRED)
     nng_check_sym(atomic_flag_test_and_set stdatomic.h NNG_HAVE_STDATOMIC)
     nng_check_sym(socketpair sys/socket.h NNG_HAVE_SOCKETPAIR)
+    nng_check_sym(AF_INET6 netinet/in.h NNG_HAVE_INET6)
 
     nng_sources(
             posix_impl.h
diff --git a/src/platform/posix/posix_resolv_gai.c b/src/platform/posix/posix_resolv_gai.c
index 8eaa29f2..f522499e 100644
--- a/src/platform/posix/posix_resolv_gai.c
+++ b/src/platform/posix/posix_resolv_gai.c
@@ -33,6 +33,10 @@
 #define AI_NUMERICSERV 0
 #endif
 
+#ifndef NNG_HAVE_INET6
+#undef NNG_ENABLE_IPV6
+#endif
+
 static nni_mtx  resolv_mtx  = NNI_MTX_INITIALIZER;
 static nni_cv   resolv_cv   = NNI_CV_INITIALIZER(&resolv_mtx);
 static bool     resolv_fini = false;
@@ -182,17 +186,23 @@ resolv_task(resolv_item *item)
 
 	rv = NNG_EADDRINVAL;
 	for (probe = results; probe != NULL; probe = probe->ai_next) {
-		if ((probe->ai_addr->sa_family == AF_INET) ||
-		    (probe->ai_addr->sa_family == AF_INET6)) {
+		if (probe->ai_addr->sa_family == AF_INET) {
 			break;
 		}
+#ifdef NNG_ENABLE_IPV6
+		if (probe->ai_addr->sa_family == AF_INET6) {
+			break;
+		}
+#endif
 	}
 
 	nni_mtx_lock(&resolv_mtx);
 	if ((probe != NULL) && (item->aio != NULL)) {
-		struct sockaddr_in  *sin;
+		struct sockaddr_in *sin;
+#ifdef NNG_ENABLE_IPV6
 		struct sockaddr_in6 *sin6;
-		nng_sockaddr        *sa = item->sa;
+#endif
+		nng_sockaddr *sa = item->sa;
 
 		switch (probe->ai_addr->sa_family) {
 		case AF_INET:
@@ -202,6 +212,7 @@ resolv_task(resolv_item *item)
 			sa->s_in.sa_port   = sin->sin_port;
 			sa->s_in.sa_addr   = sin->sin_addr.s_addr;
 			break;
+#ifdef NNG_ENABLE_IPV6
 		case AF_INET6:
 			rv                  = 0;
 			sin6                = (void *) probe->ai_addr;
@@ -210,6 +221,7 @@ resolv_task(resolv_item *item)
 			sa->s_in6.sa_scope  = sin6->sin6_scope_id;
 			memcpy(sa->s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
 			break;
+#endif
 		}
 	}
 	nni_mtx_unlock(&resolv_mtx);
@@ -238,12 +250,20 @@ nni_resolv_ip(const char *host, const char *serv, int af, bool passive,
 	case NNG_AF_INET:
 		fam = AF_INET;
 		break;
+
+#ifdef NNG_ENABLE_IPV6
 	case NNG_AF_INET6:
 		fam = AF_INET6;
 		break;
 	case NNG_AF_UNSPEC:
 		fam = AF_UNSPEC;
 		break;
+#else
+	case NNG_AF_UNSPEC:
+		fam = AF_INET;
+		break;
+#endif
+
 	default:
 		nni_aio_finish_error(aio, NNG_ENOTSUP);
 		return;
@@ -342,13 +362,17 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 	struct addrinfo  hints;
 	struct addrinfo *results;
 	int              rv;
-	bool             v6      = false;
-	bool             wrapped = false;
 	char            *port;
 	char            *host;
 	char            *buf;
 	size_t           buf_len;
 
+#ifdef NNG_ENABLE_IPV6
+	bool  v6      = false;
+	bool  wrapped = false;
+	char *s;
+#endif
+
 	if (addr == NULL) {
 		addr = "";
 	}
@@ -359,12 +383,12 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 	}
 	memcpy(buf, addr, buf_len);
 	host = buf;
+#ifdef NNG_ENABLE_IPV6
 	if (*host == '[') {
 		v6      = true;
 		wrapped = true;
 		host++;
 	} else {
-		char *s;
 		for (s = host; *s != '\0'; s++) {
 			if (*s == '.') {
 				break;
@@ -394,6 +418,13 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 		rv = NNG_EADDRINVAL;
 		goto done;
 	}
+#else  // NNG_ENABLE_IPV6
+	for (port = host; *port != '\0'; port++) {
+		if (*port == ':') {
+			break;
+		}
+	}
+#endif // NNG_ENABLE_IPV6
 
 	if ((!want_port) && (*port != '\0')) {
 		rv = NNG_EADDRINVAL;
@@ -408,9 +439,13 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_flags = AI_NUMERICSERV | AI_NUMERICHOST | AI_PASSIVE;
+#ifdef NNG_ENABLE_IPV6
 	if (v6) {
 		hints.ai_family = AF_INET6;
 	}
+#else
+	hints.ai_family = AF_INET;
+#endif
 #ifdef AI_ADDRCONFIG
 	hints.ai_flags |= AI_ADDRCONFIG;
 #endif
diff --git a/src/platform/posix/posix_sockaddr.c b/src/platform/posix/posix_sockaddr.c
index a569132c..63707310 100644
--- a/src/platform/posix/posix_sockaddr.c
+++ b/src/platform/posix/posix_sockaddr.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -22,17 +22,23 @@
 #include <sys/types.h>
 #include <sys/un.h>
 
+#ifndef NNG_HAVE_INET6
+#undef NNG_ENABLE_IPV6
+#endif
+
 size_t
 nni_posix_nn2sockaddr(void *sa, const nni_sockaddr *na)
 {
-	struct sockaddr_in *         sin;
-	struct sockaddr_in6 *        sin6;
-	struct sockaddr_un *         spath;
-	const nng_sockaddr_in *      nsin;
-	const nng_sockaddr_in6 *     nsin6;
-	const nng_sockaddr_path *    nspath;
+	struct sockaddr_in          *sin;
+	struct sockaddr_un          *spath;
+	const nng_sockaddr_in       *nsin;
+	const nng_sockaddr_path     *nspath;
 	const nng_sockaddr_abstract *nsabs;
 	size_t                       sz;
+#ifdef NNG_ENABLE_IPV6
+	struct sockaddr_in6    *sin6;
+	const nng_sockaddr_in6 *nsin6;
+#endif
 
 	if ((sa == NULL) || (na == NULL)) {
 		return (0);
@@ -47,6 +53,7 @@ nni_posix_nn2sockaddr(void *sa, const nni_sockaddr *na)
 		sin->sin_addr.s_addr = nsin->sa_addr;
 		return (sizeof(*sin));
 
+#ifdef NNG_ENABLE_IPV6
 	case NNG_AF_INET6:
 		sin6  = (void *) sa;
 		nsin6 = &na->s_in6;
@@ -59,6 +66,7 @@ nni_posix_nn2sockaddr(void *sa, const nni_sockaddr *na)
 		sin6->sin6_scope_id = nsin6->sa_scope;
 		memcpy(sin6->sin6_addr.s6_addr, nsin6->sa_addr, 16);
 		return (sizeof(*sin6));
+#endif
 
 	case NNG_AF_IPC:
 		spath  = (void *) sa;
@@ -75,18 +83,18 @@ nni_posix_nn2sockaddr(void *sa, const nni_sockaddr *na)
 	case NNG_AF_ABSTRACT:
 		spath = (void *) sa;
 		nsabs = &na->s_abstract;
-		if (nsabs->sa_len >= sizeof (spath->sun_path)) {
+		if (nsabs->sa_len >= sizeof(spath->sun_path)) {
 			return (0);
 		}
 		memset(spath, 0, sizeof(*spath));
-		spath->sun_family = PF_UNIX;
+		spath->sun_family  = PF_UNIX;
 		spath->sun_path[0] = '\0'; // abstract starts with nul
 
 		// We support auto-bind with an empty string.  There is
 		// a subtle caveat here, which is that we cannot bind to
 		// the *empty* name.
 		if (nsabs->sa_len == 0) {
-			return (sizeof (sa_family_t)); // auto bind
+			return (sizeof(sa_family_t)); // auto bind
 		} else {
 			memcpy(&spath->sun_path[1], nsabs->sa_name,
 			    nsabs->sa_len);
@@ -99,13 +107,15 @@ nni_posix_nn2sockaddr(void *sa, const nni_sockaddr *na)
 int
 nni_posix_sockaddr2nn(nni_sockaddr *na, const void *sa, size_t sz)
 {
-	const struct sockaddr_in * sin;
+	const struct sockaddr_in *sin;
+	const struct sockaddr_un *spath;
+	nng_sockaddr_in          *nsin;
+	nng_sockaddr_path        *nspath;
+	nng_sockaddr_abstract    *nsabs;
+#ifdef NNG_ENABLE_IPV6
 	const struct sockaddr_in6 *sin6;
-	const struct sockaddr_un * spath;
-	nng_sockaddr_in *          nsin;
-	nng_sockaddr_in6 *         nsin6;
-	nng_sockaddr_path *        nspath;
-	nng_sockaddr_abstract *    nsabs;
+	nng_sockaddr_in6          *nsin6;
+#endif
 
 	if ((na == NULL) || (sa == NULL)) {
 		return (-1);
@@ -121,6 +131,8 @@ nni_posix_sockaddr2nn(nni_sockaddr *na, const void *sa, size_t sz)
 		nsin->sa_port   = sin->sin_port;
 		nsin->sa_addr   = sin->sin_addr.s_addr;
 		break;
+
+#ifdef NNG_ENABLE_IPV6
 	case AF_INET6:
 		if (sz < sizeof(*sin6)) {
 			return (-1);
@@ -132,6 +144,8 @@ nni_posix_sockaddr2nn(nni_sockaddr *na, const void *sa, size_t sz)
 		nsin6->sa_scope  = sin6->sin6_scope_id;
 		memcpy(nsin6->sa_addr, sin6->sin6_addr.s6_addr, 16);
 		break;
+#endif
+
 	case AF_UNIX:
 		// AF_UNIX can be NNG_AF_IPC, or NNG_AF_ABSTRACT.
 		spath = (void *) sa;
@@ -153,7 +167,7 @@ nni_posix_sockaddr2nn(nni_sockaddr *na, const void *sa, size_t sz)
 			nsabs->sa_len    = sz - 1;
 			memcpy(nsabs->sa_name, &spath->sun_path[1], sz - 1);
 		} else {
-                        nspath            = &na->s_ipc;
+			nspath            = &na->s_ipc;
 			nspath->sa_family = NNG_AF_IPC;
 			nni_strlcpy(nspath->sa_path, spath->sun_path,
 			    sizeof(nspath->sa_path));
diff --git a/src/platform/posix/posix_tcpdial.c b/src/platform/posix/posix_tcpdial.c
index 0af72cfa..cf3d9368 100644
--- a/src/platform/posix/posix_tcpdial.c
+++ b/src/platform/posix/posix_tcpdial.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2018 Devolutions <info@devolutions.net>
 //
@@ -23,6 +23,10 @@
 
 #include "posix_tcp.h"
 
+#ifndef NNG_HAVE_INET6
+#undef NNG_ENABLE_IPV6
+#endif
+
 // Dialer stuff.
 int
 nni_tcp_dialer_init(nni_tcp_dialer **dp)
@@ -93,7 +97,7 @@ static void
 tcp_dialer_cancel(nni_aio *aio, void *arg, int rv)
 {
 	nni_tcp_dialer *d = arg;
-	nni_tcp_conn *  c;
+	nni_tcp_conn   *c;
 
 	nni_mtx_lock(&d->mtx);
 	if ((!nni_aio_list_active(aio)) ||
@@ -113,9 +117,9 @@ tcp_dialer_cancel(nni_aio *aio, void *arg, int rv)
 static void
 tcp_dialer_cb(nni_posix_pfd *pfd, unsigned ev, void *arg)
 {
-	nni_tcp_conn *  c = arg;
+	nni_tcp_conn   *c = arg;
 	nni_tcp_dialer *d = c->dialer;
-	nni_aio *       aio;
+	nni_aio        *aio;
 	int             rv;
 	int             ka;
 	int             nd;
@@ -171,8 +175,8 @@ tcp_dialer_cb(nni_posix_pfd *pfd, unsigned ev, void *arg)
 void
 nni_tcp_dial(nni_tcp_dialer *d, const nni_sockaddr *sa, nni_aio *aio)
 {
-	nni_tcp_conn *          c;
-	nni_posix_pfd *         pfd = NULL;
+	nni_tcp_conn           *c;
+	nni_posix_pfd          *pfd = NULL;
 	struct sockaddr_storage ss;
 	size_t                  sslen;
 	int                     fd;
@@ -333,13 +337,15 @@ tcp_dialer_get_locaddr(void *arg, void *buf, size_t *szp, nni_type t)
 static int
 tcp_dialer_set_locaddr(void *arg, const void *buf, size_t sz, nni_type t)
 {
-	nni_tcp_dialer *        d = arg;
+	nni_tcp_dialer         *d = arg;
 	nng_sockaddr            sa;
 	struct sockaddr_storage ss;
-	struct sockaddr_in *    sin;
-	struct sockaddr_in6 *   sin6;
+	struct sockaddr_in     *sin;
 	size_t                  len;
 	int                     rv;
+#ifdef NNG_ENABLE_IPV6
+	struct sockaddr_in6 *sin6;
+#endif
 
 	if ((rv = nni_copyin_sockaddr(&sa, buf, sz, t)) != 0) {
 		return (rv);
@@ -356,12 +362,16 @@ tcp_dialer_set_locaddr(void *arg, const void *buf, size_t sz, nni_type t)
 			return (NNG_EADDRINVAL);
 		}
 		break;
+
+#ifdef NNG_ENABLE_IPV6
 	case AF_INET6:
 		sin6 = (void *) &ss;
 		if (sin6->sin6_port != 0) {
 			return (NNG_EADDRINVAL);
 		}
 		break;
+#endif // __NG_INET6
+
 	default:
 		return (NNG_EADDRINVAL);
 	}
diff --git a/src/platform/posix/posix_tcplisten.c b/src/platform/posix/posix_tcplisten.c
index e1c0b90c..95be4beb 100644
--- a/src/platform/posix/posix_tcplisten.c
+++ b/src/platform/posix/posix_tcplisten.c
@@ -27,6 +27,10 @@
 #define SOCK_CLOEXEC 0
 #endif
 
+#ifndef NNG_HAVE_INET6
+#undef NNG_ENABLE_IPV6
+#endif
+
 #include "posix_tcp.h"
 
 struct nni_tcp_listener {
@@ -94,7 +98,7 @@ tcp_listener_doaccept(nni_tcp_listener *l)
 		int            nd;
 		int            ka;
 		nni_posix_pfd *pfd;
-		nni_tcp_conn * c;
+		nni_tcp_conn  *c;
 
 		fd = nni_posix_pfd_fd(l->pfd);
 
@@ -203,10 +207,15 @@ nni_tcp_listener_listen(nni_tcp_listener *l, const nni_sockaddr *sa)
 	struct sockaddr_storage ss;
 	int                     rv;
 	int                     fd;
-	nni_posix_pfd *         pfd;
+	nni_posix_pfd          *pfd;
 
 	if (((len = nni_posix_nn2sockaddr(&ss, sa)) == 0) ||
-	    ((ss.ss_family != AF_INET) && (ss.ss_family != AF_INET6))) {
+#ifdef NNG_ENABLE_IPV6
+	    ((ss.ss_family != AF_INET) && (ss.ss_family != AF_INET6))
+#else
+	    (ss.ss_family != AF_INET)
+#endif
+	) {
 		return (NNG_EADDRINVAL);
 	}
 
diff --git a/src/platform/resolver_test.c b/src/platform/resolver_test.c
index d4dd4465..ed88d09d 100644
--- a/src/platform/resolver_test.c
+++ b/src/platform/resolver_test.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -12,12 +12,33 @@
 
 #include <nuts.h>
 
+#ifdef NNG_ENABLE_IPV6
 uint8_t v6loop[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 };
 
+static bool
+has_v6(void)
+{
+	nng_sockaddr  sa;
+	nni_plat_udp *u;
+	int           rv;
+
+	nni_init(); // ensure that platform poller is up
+	sa.s_in6.sa_family = NNG_AF_INET6;
+	sa.s_in6.sa_port   = 0;
+	memcpy(sa.s_in6.sa_addr, v6loop, 16);
+
+	rv = nni_plat_udp_open(&u, &sa);
+	if (rv == 0) {
+		nni_plat_udp_close(u);
+	}
+	return (rv == 0);
+}
+#endif
+
 void
 test_google_dns(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -34,7 +55,7 @@ test_google_dns(void)
 void
 test_numeric_addr(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -47,19 +68,17 @@ test_numeric_addr(void)
 	nng_aio_free(aio);
 }
 
+#ifdef NNG_ENABLE_IPV6
 void
 test_numeric_v6(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
-	// Travis CI has moved some of their services to host that
-	// apparently don't support IPv6 at all.  This is very sad.
-	// CircleCI 2.0 is in the same boat.  (Amazon to blame.)
-	if ((getenv("TRAVIS") != NULL) || (getenv("CIRCLECI") != NULL)) {
-		return; // skip this one.
+	if (!has_v6()) {
+		return;
 	}
-
+	NUTS_MSG("IPV6 support present");
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
 	nni_resolv_ip("::1", "80", NNG_AF_INET6, true, &sa, aio);
 	nng_aio_wait(aio);
@@ -69,11 +88,12 @@ test_numeric_v6(void)
 	NUTS_TRUE(memcmp(sa.s_in6.sa_addr, v6loop, 16) == 0);
 	nng_aio_free(aio);
 }
+#endif
 
 void
 test_service_names(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -88,7 +108,7 @@ test_service_names(void)
 void
 test_localhost_v4(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -104,7 +124,7 @@ test_localhost_v4(void)
 void
 test_localhost_unspecified(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -118,10 +138,12 @@ test_localhost_unspecified(void)
 		NUTS_TRUE(sa.s_in.sa_port == nuts_be16(80));
 		NUTS_TRUE(sa.s_in.sa_addr == nuts_be32(0x7f000001));
 		break;
+#ifdef NNG_ENABLE_IPV6
 	case NNG_AF_INET6:
 		NUTS_TRUE(sa.s_in6.sa_port == nuts_be16(80));
 		NUTS_TRUE(memcmp(sa.s_in6.sa_addr, v6loop, 16) == 0);
 		break;
+#endif
 	}
 	nng_aio_free(aio);
 }
@@ -129,7 +151,7 @@ test_localhost_unspecified(void)
 void
 test_null_passive(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -145,7 +167,7 @@ test_null_passive(void)
 void
 test_null_not_passive(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -166,7 +188,7 @@ test_null_not_passive(void)
 void
 test_bad_port_number(void)
 {
-	nng_aio *    aio;
+	nng_aio     *aio;
 	nng_sockaddr sa;
 
 	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
@@ -179,7 +201,9 @@ test_bad_port_number(void)
 NUTS_TESTS = {
 	{ "resolve google dns", test_google_dns },
 	{ "resolve numeric addr", test_numeric_addr },
+#ifdef NNG_ENABLE_IPV6
 	{ "resolve numeric v6", test_numeric_v6 },
+#endif
 	{ "resolve service names", test_service_names },
 	{ "resolve localhost v4", test_localhost_v4 },
 	{ "resolve localhost unspecified", test_localhost_unspecified },
diff --git a/src/platform/windows/win_resolv.c b/src/platform/windows/win_resolv.c
index 92c7461f..4f353e08 100644
--- a/src/platform/windows/win_resolv.c
+++ b/src/platform/windows/win_resolv.c
@@ -148,17 +148,23 @@ resolv_task(resolv_item *item)
 
 	rv = NNG_EADDRINVAL;
 	for (probe = results; probe != NULL; probe = probe->ai_next) {
-		if ((probe->ai_addr->sa_family == AF_INET) ||
-		    (probe->ai_addr->sa_family == AF_INET6)) {
+		if (probe->ai_addr->sa_family == AF_INET) {
 			break;
 		}
+#if NNG_ENABLE_IPV6
+		if (probe->ai_addr->sa_family == AF_INET6) {
+			break;
+		}
+#endif
 	}
 
 	nni_mtx_lock(&resolv_mtx);
 	if ((probe != NULL) && (item->aio != NULL)) {
-		struct sockaddr_in  *sin;
+		struct sockaddr_in *sin;
+#ifdef NNG_ENABLE_IPV6
 		struct sockaddr_in6 *sin6;
-		nni_sockaddr        *sa;
+#endif
+		nni_sockaddr *sa;
 
 		sa = item->sa;
 
@@ -170,6 +176,7 @@ resolv_task(resolv_item *item)
 			sa->s_in.sa_port   = sin->sin_port;
 			sa->s_in.sa_addr   = sin->sin_addr.s_addr;
 			break;
+#ifdef NNG_ENABLE_IPV6
 		case AF_INET6:
 			rv                  = 0;
 			sin6                = (void *) probe->ai_addr;
@@ -178,6 +185,7 @@ resolv_task(resolv_item *item)
 			sa->s_in6.sa_scope  = sin6->sin6_scope_id;
 			memcpy(sa->s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
 			break;
+#endif
 		}
 	}
 	nni_mtx_unlock(&resolv_mtx);
@@ -205,12 +213,18 @@ nni_resolv_ip(const char *host, const char *serv, int family, bool passive,
 	case NNG_AF_INET:
 		fam = AF_INET;
 		break;
+#ifdef NNG_ENABLE_IPV6
 	case NNG_AF_INET6:
 		fam = AF_INET6;
 		break;
 	case NNG_AF_UNSPEC:
 		fam = AF_UNSPEC;
 		break;
+#else
+	case NNG_AF_UNSPEC:
+		fam = AF_INET;
+		break;
+#endif
 	default:
 		nni_aio_finish_error(aio, NNG_ENOTSUP);
 		return;
@@ -306,12 +320,15 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 	struct addrinfo  hints;
 	struct addrinfo *results;
 	int              rv;
-	bool             v6      = false;
-	bool             wrapped = false;
 	char            *port;
 	char            *host;
 	char            *buf;
 	size_t           buf_len;
+#ifdef NNG_ENABLE_IPV6
+	bool  v6      = false;
+	bool  wrapped = false;
+	char *s;
+#endif
 
 	if (addr == NULL) {
 		addr = "";
@@ -323,12 +340,13 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 	}
 	memcpy(buf, addr, buf_len);
 	host = buf;
+
+#ifdef NNG_ENABLE_IPV6
 	if (*host == '[') {
 		v6      = true;
 		wrapped = true;
 		host++;
 	} else {
-		char *s;
 		for (s = host; *s != '\0'; s++) {
 			if (*s == '.') {
 				break;
@@ -358,6 +376,13 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 		rv = NNG_EADDRINVAL;
 		goto done;
 	}
+#else // NNG_ENABLE_IPV6
+	for (port = host; *port != '\0'; port++) {
+		if (*port == ':') {
+			break;
+		}
+	}
+#endif
 
 	if ((!want_port) && (*port != '\0')) {
 		rv = NNG_EADDRINVAL;
@@ -373,9 +398,13 @@ parse_ip(const char *addr, nng_sockaddr *sa, bool want_port)
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_flags =
 	    AI_ADDRCONFIG | AI_NUMERICSERV | AI_NUMERICHOST | AI_PASSIVE;
+#ifdef NNG_ENABLE_IPV6
 	if (v6) {
 		hints.ai_family = AF_INET6;
 	}
+#else
+	hints.ai_family = AF_INET;
+#endif
 
 	rv = getaddrinfo(host, port, &hints, &results);
 	if ((rv != 0) || (results == NULL)) {
diff --git a/src/platform/windows/win_sockaddr.c b/src/platform/windows/win_sockaddr.c
index 818f670b..585096e9 100644
--- a/src/platform/windows/win_sockaddr.c
+++ b/src/platform/windows/win_sockaddr.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -15,8 +15,10 @@
 int
 nni_win_nn2sockaddr(SOCKADDR_STORAGE *ss, const nni_sockaddr *sa)
 {
-	SOCKADDR_IN * sin;
+	SOCKADDR_IN *sin;
+#ifdef NNG_ENABLE_IPV6
 	SOCKADDR_IN6 *sin6;
+#endif
 
 	if ((ss == NULL) || (sa == NULL)) {
 		return (-1);
@@ -30,6 +32,7 @@ nni_win_nn2sockaddr(SOCKADDR_STORAGE *ss, const nni_sockaddr *sa)
 		sin->sin_addr.s_addr = sa->s_in.sa_addr;
 		return (sizeof(*sin));
 
+#ifdef NNG_ENABLE_IPV6
 	case NNG_AF_INET6:
 		sin6 = (void *) ss;
 		memset(sin6, 0, sizeof(*sin6));
@@ -38,6 +41,7 @@ nni_win_nn2sockaddr(SOCKADDR_STORAGE *ss, const nni_sockaddr *sa)
 		sin6->sin6_scope_id = sa->s_in6.sa_scope;
 		memcpy(sin6->sin6_addr.s6_addr, sa->s_in6.sa_addr, 16);
 		return (sizeof(*sin6));
+#endif
 	}
 	return (-1);
 }
@@ -45,8 +49,10 @@ nni_win_nn2sockaddr(SOCKADDR_STORAGE *ss, const nni_sockaddr *sa)
 int
 nni_win_sockaddr2nn(nni_sockaddr *sa, const SOCKADDR_STORAGE *ss)
 {
-	SOCKADDR_IN * sin;
+	SOCKADDR_IN *sin;
+#ifdef NNG_ENABLE_IPV6
 	SOCKADDR_IN6 *sin6;
+#endif
 
 	if ((ss == NULL) || (sa == NULL)) {
 		return (-1);
@@ -59,6 +65,7 @@ nni_win_sockaddr2nn(nni_sockaddr *sa, const SOCKADDR_STORAGE *ss)
 		sa->s_in.sa_addr   = sin->sin_addr.s_addr;
 		return (0);
 
+#ifdef NNG_ENABLE_IPV6
 	case PF_INET6:
 		sin6                = (void *) ss;
 		sa->s_in6.sa_family = NNG_AF_INET6;
@@ -66,6 +73,7 @@ nni_win_sockaddr2nn(nni_sockaddr *sa, const SOCKADDR_STORAGE *ss)
 		sa->s_in6.sa_scope  = sin6->sin6_scope_id;
 		memcpy(sa->s_in6.sa_addr, sin6->sin6_addr.s6_addr, 16);
 		return (0);
+#endif
 	}
 	return (-1);
 }
diff --git a/src/platform/windows/win_tcpdial.c b/src/platform/windows/win_tcpdial.c
index 9463c241..b4a6d745 100644
--- a/src/platform/windows/win_tcpdial.c
+++ b/src/platform/windows/win_tcpdial.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2018 Devolutions <info@devolutions.net>
 //
@@ -113,7 +113,7 @@ static void
 tcp_dial_cancel(nni_aio *aio, void *arg, int rv)
 {
 	nni_tcp_dialer *d = arg;
-	nni_tcp_conn *  c;
+	nni_tcp_conn   *c;
 
 	nni_mtx_lock(&d->mtx);
 	if ((c = nni_aio_get_prov_data(aio)) != NULL) {
@@ -128,9 +128,9 @@ tcp_dial_cancel(nni_aio *aio, void *arg, int rv)
 static void
 tcp_dial_cb(nni_win_io *io, int rv, size_t cnt)
 {
-	nni_tcp_conn *  c   = io->ptr;
+	nni_tcp_conn   *c   = io->ptr;
 	nni_tcp_dialer *d   = c->dialer;
-	nni_aio *       aio = c->conn_aio;
+	nni_aio        *aio = c->conn_aio;
 	BOOL            ka;
 	BOOL            nd;
 
@@ -183,7 +183,7 @@ 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;
+	nni_tcp_conn    *c;
 	int              rv;
 
 	if (nni_aio_begin(aio) != 0) {
@@ -335,13 +335,15 @@ tcp_dialer_get_locaddr(void *arg, void *buf, size_t *szp, nni_type t)
 static int
 tcp_dialer_set_locaddr(void *arg, const void *buf, size_t sz, nni_type t)
 {
-	nni_tcp_dialer *     d = arg;
-	nng_sockaddr         sa;
-	SOCKADDR_STORAGE     ss;
-	struct sockaddr_in * sin;
+	nni_tcp_dialer     *d = arg;
+	nng_sockaddr        sa;
+	SOCKADDR_STORAGE    ss;
+	struct sockaddr_in *sin;
+	size_t              sslen;
+	int                 rv;
+#ifdef NNG_ENABLE_IPV6
 	struct sockaddr_in6 *sin6;
-	size_t               sslen;
-	int                  rv;
+#endif
 
 	if ((rv = nni_copyin_sockaddr(&sa, buf, sz, t)) != 0) {
 		return (rv);
@@ -358,12 +360,14 @@ tcp_dialer_set_locaddr(void *arg, const void *buf, size_t sz, nni_type t)
 			return (NNG_EADDRINVAL);
 		}
 		break;
+#ifdef NNG_ENABLE_IPV6
 	case AF_INET6:
 		sin6 = (void *) &ss;
 		if (sin6->sin6_port != 0) {
 			return (NNG_EADDRINVAL);
 		}
 		break;
+#endif
 	default:
 		return (NNG_EADDRINVAL);
 	}
diff --git a/src/sp/protocol.c b/src/sp/protocol.c
index 512b27cc..d64c85a3 100644
--- a/src/sp/protocol.c
+++ b/src/sp/protocol.c
@@ -12,7 +12,6 @@
 
 #include "core/nng_impl.h"
 
-
 int
 nni_proto_open(nng_socket *sip, const nni_proto *proto)
 {
@@ -21,8 +20,8 @@ nni_proto_open(nng_socket *sip, const nni_proto *proto)
 
 	if ((rv = nni_sock_open(&sock, proto)) == 0) {
 		nng_socket s;
-		s.id     = nni_sock_id(sock); // Keep socket held open.
-		*sip     = s;
+		s.id = nni_sock_id(sock); // Keep socket held open.
+		*sip = s;
 	}
 	return (rv);
 }
diff --git a/src/sp/transport/tcp/tcp.c b/src/sp/transport/tcp/tcp.c
index 1b2a380c..a9075938 100644
--- a/src/sp/transport/tcp/tcp.c
+++ b/src/sp/transport/tcp/tcp.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2019 Devolutions <info@devolutions.net>
 //
@@ -22,14 +22,14 @@ typedef struct tcptran_ep   tcptran_ep;
 
 // tcp_pipe is one end of a TCP connection.
 struct tcptran_pipe {
-	nng_stream *    conn;
-	nni_pipe *      npipe;
+	nng_stream     *conn;
+	nni_pipe       *npipe;
 	uint16_t        peer;
 	uint16_t        proto;
 	size_t          rcvmax;
 	bool            closed;
 	nni_list_node   node;
-	tcptran_ep *    ep;
+	tcptran_ep     *ep;
 	nni_atomic_flag reaped;
 	nni_reap_node   reap;
 	uint8_t         txlen[sizeof(uint64_t)];
@@ -40,10 +40,10 @@ struct tcptran_pipe {
 	size_t          wantrxhead;
 	nni_list        recvq;
 	nni_list        sendq;
-	nni_aio *       txaio;
-	nni_aio *       rxaio;
-	nni_aio *       negoaio;
-	nni_msg *       rxmsg;
+	nni_aio        *txaio;
+	nni_aio        *rxaio;
+	nni_aio        *negoaio;
+	nni_msg        *rxmsg;
 	nni_mtx         mtx;
 };
 
@@ -54,18 +54,18 @@ struct tcptran_ep {
 	bool                 fini;
 	bool                 started;
 	bool                 closed;
-	nng_url *            url;
-	const char *         host; // for dialers
+	nng_url             *url;
+	const char          *host; // for dialers
 	nng_sockaddr         src;
 	int                  refcnt; // active pipes
-	nni_aio *            useraio;
-	nni_aio *            connaio;
-	nni_aio *            timeaio;
+	nni_aio             *useraio;
+	nni_aio             *connaio;
+	nni_aio             *timeaio;
 	nni_list             busypipes; // busy pipes -- ones passed to socket
 	nni_list             waitpipes; // pipes waiting to match to socket
 	nni_list             negopipes; // pipes busy negotiating
 	nni_reap_node        reap;
-	nng_stream_dialer *  dialer;
+	nng_stream_dialer   *dialer;
 	nng_stream_listener *listener;
 
 #ifdef NNG_ENABLE_STATS
@@ -140,7 +140,7 @@ static void
 tcptran_pipe_fini(void *arg)
 {
 	tcptran_pipe *p = arg;
-	tcptran_ep *  ep;
+	tcptran_ep   *ep;
 
 	tcptran_pipe_stop(p);
 	if ((ep = p->ep) != NULL) {
@@ -202,7 +202,7 @@ tcptran_pipe_alloc(tcptran_pipe **pipep)
 static void
 tcptran_ep_match(tcptran_ep *ep)
 {
-	nni_aio *     aio;
+	nni_aio      *aio;
 	tcptran_pipe *p;
 
 	if (((aio = ep->useraio) == NULL) ||
@@ -221,9 +221,9 @@ static void
 tcptran_pipe_nego_cb(void *arg)
 {
 	tcptran_pipe *p   = arg;
-	tcptran_ep *  ep  = p->ep;
-	nni_aio *     aio = p->negoaio;
-	nni_aio *     uaio;
+	tcptran_ep   *ep  = p->ep;
+	nni_aio      *aio = p->negoaio;
+	nni_aio      *uaio;
 	int           rv;
 
 	nni_mtx_lock(&ep->mtx);
@@ -302,10 +302,10 @@ tcptran_pipe_send_cb(void *arg)
 {
 	tcptran_pipe *p = arg;
 	int           rv;
-	nni_aio *     aio;
+	nni_aio      *aio;
 	size_t        n;
-	nni_msg *     msg;
-	nni_aio *     txaio = p->txaio;
+	nni_msg      *msg;
+	nni_aio      *txaio = p->txaio;
 
 	nni_mtx_lock(&p->mtx);
 	aio = nni_list_first(&p->sendq);
@@ -348,11 +348,11 @@ static void
 tcptran_pipe_recv_cb(void *arg)
 {
 	tcptran_pipe *p = arg;
-	nni_aio *     aio;
+	nni_aio      *aio;
 	int           rv;
 	size_t        n;
-	nni_msg *     msg;
-	nni_aio *     rxaio = p->rxaio;
+	nni_msg      *msg;
+	nni_aio      *rxaio = p->rxaio;
 
 	nni_mtx_lock(&p->mtx);
 	aio = nni_list_first(&p->recvq);
@@ -678,7 +678,7 @@ tcptran_ep_fini(void *arg)
 static void
 tcptran_ep_close(void *arg)
 {
-	tcptran_ep *  ep = arg;
+	tcptran_ep   *ep = arg;
 	tcptran_pipe *p;
 
 	nni_mtx_lock(&ep->mtx);
@@ -715,8 +715,8 @@ static int
 tcptran_url_parse_source(nng_url *url, nng_sockaddr *sa, const nng_url *surl)
 {
 	int      af;
-	char *   semi;
-	char *   src;
+	char    *semi;
+	char    *src;
 	size_t   len;
 	int      rv;
 	nni_aio *aio;
@@ -740,8 +740,10 @@ tcptran_url_parse_source(nng_url *url, nng_sockaddr *sa, const nng_url *surl)
 		af = NNG_AF_UNSPEC;
 	} else if (strcmp(surl->u_scheme, "tcp4") == 0) {
 		af = NNG_AF_INET;
+#ifdef NNG_ENABLE_IPV6
 	} else if (strcmp(surl->u_scheme, "tcp6") == 0) {
 		af = NNG_AF_INET6;
+#endif
 	} else {
 		return (NNG_EADDRINVAL);
 	}
@@ -777,11 +779,11 @@ tcptran_timer_cb(void *arg)
 static void
 tcptran_accept_cb(void *arg)
 {
-	tcptran_ep *  ep  = arg;
-	nni_aio *     aio = ep->connaio;
+	tcptran_ep   *ep  = arg;
+	nni_aio      *aio = ep->connaio;
 	tcptran_pipe *p;
 	int           rv;
-	nng_stream *  conn;
+	nng_stream   *conn;
 
 	nni_mtx_lock(&ep->mtx);
 
@@ -832,11 +834,11 @@ error:
 static void
 tcptran_dial_cb(void *arg)
 {
-	tcptran_ep *  ep  = arg;
-	nni_aio *     aio = ep->connaio;
+	tcptran_ep   *ep  = arg;
+	nni_aio      *aio = ep->connaio;
 	tcptran_pipe *p;
 	int           rv;
-	nng_stream *  conn;
+	nng_stream   *conn;
 
 	if ((rv = nni_aio_result(aio)) != 0) {
 		goto error;
@@ -905,10 +907,10 @@ tcptran_ep_init(tcptran_ep **epp, nng_url *url, nni_sock *sock)
 static int
 tcptran_dialer_init(void **dp, nng_url *url, nni_dialer *ndialer)
 {
-	tcptran_ep * ep;
+	tcptran_ep  *ep;
 	int          rv;
 	nng_sockaddr srcsa;
-	nni_sock *   sock = nni_dialer_sock(ndialer);
+	nni_sock    *sock = nni_dialer_sock(ndialer);
 	nng_url      myurl;
 
 	// Check for invalid URL components.
@@ -954,7 +956,7 @@ tcptran_listener_init(void **lp, nng_url *url, nni_listener *nlistener)
 {
 	tcptran_ep *ep;
 	int         rv;
-	nni_sock *  sock = nni_listener_sock(nlistener);
+	nni_sock   *sock = nni_listener_sock(nlistener);
 
 	// Check for invalid URL components.
 	if ((strlen(url->u_path) != 0) && (strcmp(url->u_path, "/") != 0)) {
@@ -1030,7 +1032,7 @@ static int
 tcptran_ep_get_url(void *arg, void *v, size_t *szp, nni_opt_type t)
 {
 	tcptran_ep *ep = arg;
-	char *      s;
+	char       *s;
 	int         rv;
 	int         port = 0;
 
@@ -1243,6 +1245,7 @@ static nni_sp_tran tcp4_tran = {
 	.tran_fini     = tcptran_fini,
 };
 
+#ifdef NNG_ENABLE_IPV6
 static nni_sp_tran tcp6_tran = {
 	.tran_scheme   = "tcp6",
 	.tran_dialer   = &tcptran_dialer_ops,
@@ -1251,6 +1254,7 @@ static nni_sp_tran tcp6_tran = {
 	.tran_init     = tcptran_init,
 	.tran_fini     = tcptran_fini,
 };
+#endif
 
 #ifndef NNG_ELIDE_DEPRECATED
 int
@@ -1265,5 +1269,7 @@ nni_sp_tcp_register(void)
 {
 	nni_sp_tran_register(&tcp_tran);
 	nni_sp_tran_register(&tcp4_tran);
+#ifdef NNG_ENABLE_IPV6
 	nni_sp_tran_register(&tcp6_tran);
+#endif
 }
diff --git a/src/sp/transport/tls/tls.c b/src/sp/transport/tls/tls.c
index c6ef90de..c5e4e90d 100644
--- a/src/sp/transport/tls/tls.c
+++ b/src/sp/transport/tls/tls.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2019 Devolutions <info@devolutions.net>
 //
@@ -28,8 +28,8 @@ typedef struct tlstran_pipe     tlstran_pipe;
 
 // tlstran_pipe is one end of a TLS connection.
 struct tlstran_pipe {
-	nng_stream *    tls;
-	nni_pipe *      npipe;
+	nng_stream     *tls;
+	nni_pipe       *npipe;
 	uint16_t        peer;
 	uint16_t        proto;
 	size_t          rcvmax;
@@ -37,7 +37,7 @@ struct tlstran_pipe {
 	nni_list_node   node;
 	nni_list        sendq;
 	nni_list        recvq;
-	tlstran_ep *    ep;
+	tlstran_ep     *ep;
 	nni_sockaddr    sa;
 	nni_atomic_flag reaped;
 	nni_reap_node   reap;
@@ -47,10 +47,10 @@ struct tlstran_pipe {
 	size_t          gotrxhead;
 	size_t          wanttxhead;
 	size_t          wantrxhead;
-	nni_aio *       txaio;
-	nni_aio *       rxaio;
-	nni_aio *       negoaio;
-	nni_msg *       rxmsg;
+	nni_aio        *txaio;
+	nni_aio        *rxaio;
+	nni_aio        *negoaio;
+	nni_msg        *rxmsg;
 	nni_mtx         mtx;
 };
 
@@ -64,18 +64,18 @@ struct tlstran_ep {
 	bool                 fini;
 	int                  refcnt;
 	int                  authmode;
-	nni_url *            url;
+	nni_url             *url;
 	nni_list             pipes;
 	nni_reap_node        reap;
-	nng_stream_dialer *  dialer;
+	nng_stream_dialer   *dialer;
 	nng_stream_listener *listener;
-	nni_aio *            useraio;
-	nni_aio *            connaio;
-	nni_aio *            timeaio;
+	nni_aio             *useraio;
+	nni_aio             *connaio;
+	nni_aio             *timeaio;
 	nni_list             busypipes; // busy pipes -- ones passed to socket
 	nni_list             waitpipes; // pipes waiting to match to socket
 	nni_list             negopipes; // pipes busy negotiating
-	const char *         host;
+	const char          *host;
 	nng_sockaddr         src;
 	nng_sockaddr         sa;
 	nni_stat_item        st_rcv_max;
@@ -143,7 +143,7 @@ static void
 tlstran_pipe_fini(void *arg)
 {
 	tlstran_pipe *p = arg;
-	tlstran_ep *  ep;
+	tlstran_ep   *ep;
 
 	tlstran_pipe_stop(p);
 	if ((ep = p->ep) != NULL) {
@@ -203,7 +203,7 @@ tlstran_pipe_reap(tlstran_pipe *p)
 static void
 tlstran_ep_match(tlstran_ep *ep)
 {
-	nni_aio *     aio;
+	nni_aio      *aio;
 	tlstran_pipe *p;
 
 	if (((aio = ep->useraio) == NULL) ||
@@ -222,9 +222,9 @@ static void
 tlstran_pipe_nego_cb(void *arg)
 {
 	tlstran_pipe *p   = arg;
-	tlstran_ep *  ep  = p->ep;
-	nni_aio *     aio = p->negoaio;
-	nni_aio *     uaio;
+	tlstran_ep   *ep  = p->ep;
+	nni_aio      *aio = p->negoaio;
+	nni_aio      *uaio;
 	int           rv;
 
 	nni_mtx_lock(&ep->mtx);
@@ -302,10 +302,10 @@ tlstran_pipe_send_cb(void *arg)
 {
 	tlstran_pipe *p = arg;
 	int           rv;
-	nni_aio *     aio;
+	nni_aio      *aio;
 	size_t        n;
-	nni_msg *     msg;
-	nni_aio *     txaio = p->txaio;
+	nni_msg      *msg;
+	nni_aio      *txaio = p->txaio;
 
 	nni_mtx_lock(&p->mtx);
 	aio = nni_list_first(&p->sendq);
@@ -346,11 +346,11 @@ static void
 tlstran_pipe_recv_cb(void *arg)
 {
 	tlstran_pipe *p = arg;
-	nni_aio *     aio;
+	nni_aio      *aio;
 	int           rv;
 	size_t        n;
-	nni_msg *     msg;
-	nni_aio *     rxaio = p->rxaio;
+	nni_msg      *msg;
+	nni_aio      *rxaio = p->rxaio;
 
 	nni_mtx_lock(&p->mtx);
 	aio = nni_list_first(&p->recvq);
@@ -644,7 +644,7 @@ tlstran_ep_fini(void *arg)
 static void
 tlstran_ep_close(void *arg)
 {
-	tlstran_ep *  ep = arg;
+	tlstran_ep   *ep = arg;
 	tlstran_pipe *p;
 
 	nni_mtx_lock(&ep->mtx);
@@ -680,8 +680,8 @@ static int
 tlstran_url_parse_source(nni_url *url, nng_sockaddr *sa, const nni_url *surl)
 {
 	int      af;
-	char *   semi;
-	char *   src;
+	char    *semi;
+	char    *src;
 	size_t   len;
 	int      rv;
 	nni_aio *aio;
@@ -705,8 +705,10 @@ tlstran_url_parse_source(nni_url *url, nng_sockaddr *sa, const nni_url *surl)
 		af = NNG_AF_UNSPEC;
 	} else if (strcmp(surl->u_scheme, "tls+tcp4") == 0) {
 		af = NNG_AF_INET;
+#ifdef NNG_ENABLE_IPV6
 	} else if (strcmp(surl->u_scheme, "tls+tcp6") == 0) {
 		af = NNG_AF_INET6;
+#endif
 	} else {
 		return (NNG_EADDRINVAL);
 	}
@@ -742,11 +744,11 @@ tlstran_timer_cb(void *arg)
 static void
 tlstran_accept_cb(void *arg)
 {
-	tlstran_ep *  ep  = arg;
-	nni_aio *     aio = ep->connaio;
+	tlstran_ep   *ep  = arg;
+	nni_aio      *aio = ep->connaio;
 	tlstran_pipe *p;
 	int           rv;
-	nng_stream *  conn;
+	nng_stream   *conn;
 
 	nni_mtx_lock(&ep->mtx);
 
@@ -801,11 +803,11 @@ error:
 static void
 tlstran_dial_cb(void *arg)
 {
-	tlstran_ep *  ep  = arg;
-	nni_aio *     aio = ep->connaio;
+	tlstran_ep   *ep  = arg;
+	nni_aio      *aio = ep->connaio;
 	tlstran_pipe *p;
 	int           rv;
-	nng_stream *  conn;
+	nng_stream   *conn;
 
 	if ((rv = nni_aio_result(aio)) != 0) {
 		goto error;
@@ -873,10 +875,10 @@ tlstran_ep_init(tlstran_ep **epp, nng_url *url, nni_sock *sock)
 static int
 tlstran_ep_init_dialer(void **dp, nni_url *url, nni_dialer *ndialer)
 {
-	tlstran_ep * ep;
+	tlstran_ep  *ep;
 	int          rv;
 	nng_sockaddr srcsa;
-	nni_sock *   sock = nni_dialer_sock(ndialer);
+	nni_sock    *sock = nni_dialer_sock(ndialer);
 	nni_url      myurl;
 
 	// Check for invalid URL components.
@@ -923,16 +925,18 @@ tlstran_ep_init_listener(void **lp, nni_url *url, nni_listener *nlistener)
 	tlstran_ep *ep;
 	int         rv;
 	uint16_t    af;
-	char *      host = url->u_hostname;
-	nni_aio *   aio;
-	nni_sock *  sock = nni_listener_sock(nlistener);
+	char       *host = url->u_hostname;
+	nni_aio    *aio;
+	nni_sock   *sock = nni_listener_sock(nlistener);
 
 	if (strcmp(url->u_scheme, "tls+tcp") == 0) {
 		af = NNG_AF_UNSPEC;
 	} else if (strcmp(url->u_scheme, "tls+tcp4") == 0) {
 		af = NNG_AF_INET;
+#ifdef NNG_ENABLE_IPV6
 	} else if (strcmp(url->u_scheme, "tls+tcp6") == 0) {
 		af = NNG_AF_INET6;
+#endif
 	} else {
 		return (NNG_EADDRINVAL);
 	}
@@ -1111,7 +1115,7 @@ static int
 tlstran_ep_get_url(void *arg, void *v, size_t *szp, nni_type t)
 {
 	tlstran_ep *ep = arg;
-	char *      s;
+	char       *s;
 	int         rv;
 	int         port = 0;
 
@@ -1268,6 +1272,7 @@ static nni_sp_tran tls4_tran = {
 	.tran_fini     = tlstran_fini,
 };
 
+#ifdef NNG_ENABLE_IPV6
 static nni_sp_tran tls6_tran = {
 	.tran_scheme   = "tls+tcp6",
 	.tran_dialer   = &tlstran_dialer_ops,
@@ -1276,6 +1281,7 @@ static nni_sp_tran tls6_tran = {
 	.tran_init     = tlstran_init,
 	.tran_fini     = tlstran_fini,
 };
+#endif
 
 int
 nng_tls_register(void)
@@ -1288,5 +1294,7 @@ nni_sp_tls_register(void)
 {
 	nni_sp_tran_register(&tls_tran);
 	nni_sp_tran_register(&tls4_tran);
+#ifdef NNG_ENABLE_IPV6
 	nni_sp_tran_register(&tls6_tran);
+#endif
 }
diff --git a/src/sp/transport/ws/websocket.c b/src/sp/transport/ws/websocket.c
index a46ea58b..69509e84 100644
--- a/src/sp/transport/ws/websocket.c
+++ b/src/sp/transport/ws/websocket.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 // Copyright 2019 Devolutions <info@devolutions.net>
 //
@@ -27,7 +27,7 @@ struct ws_dialer {
 	uint16_t           peer; // remote protocol
 	nni_list           aios;
 	nni_mtx            mtx;
-	nni_aio *          connaio;
+	nni_aio           *connaio;
 	nng_stream_dialer *dialer;
 	bool               started;
 };
@@ -36,7 +36,7 @@ struct ws_listener {
 	uint16_t             peer; // remote protocol
 	nni_list             aios;
 	nni_mtx              mtx;
-	nni_aio *            accaio;
+	nni_aio             *accaio;
 	nng_stream_listener *listener;
 	bool                 started;
 };
@@ -45,10 +45,10 @@ struct ws_pipe {
 	nni_mtx     mtx;
 	bool        closed;
 	uint16_t    peer;
-	nni_aio *   user_txaio;
-	nni_aio *   user_rxaio;
-	nni_aio *   txaio;
-	nni_aio *   rxaio;
+	nni_aio    *user_txaio;
+	nni_aio    *user_rxaio;
+	nni_aio    *txaio;
+	nni_aio    *rxaio;
 	nng_stream *ws;
 };
 
@@ -396,10 +396,10 @@ wstran_listener_fini(void *arg)
 static void
 wstran_connect_cb(void *arg)
 {
-	ws_dialer * d = arg;
-	ws_pipe *   p;
-	nni_aio *   caio = d->connaio;
-	nni_aio *   uaio;
+	ws_dialer  *d = arg;
+	ws_pipe    *p;
+	nni_aio    *caio = d->connaio;
+	nni_aio    *uaio;
 	int         rv;
 	nng_stream *ws = NULL;
 
@@ -451,8 +451,8 @@ static void
 wstran_accept_cb(void *arg)
 {
 	ws_listener *l    = arg;
-	nni_aio *    aaio = l->accaio;
-	nni_aio *    uaio;
+	nni_aio     *aaio = l->accaio;
+	nni_aio     *uaio;
 	int          rv;
 
 	nni_mtx_lock(&l->mtx);
@@ -489,7 +489,7 @@ static int
 wstran_dialer_init(void **dp, nng_url *url, nni_dialer *ndialer)
 {
 	ws_dialer *d;
-	nni_sock * s = nni_dialer_sock(ndialer);
+	nni_sock  *s = nni_dialer_sock(ndialer);
 	int        rv;
 	char       name[64];
 
@@ -524,7 +524,7 @@ wstran_listener_init(void **lp, nng_url *url, nni_listener *listener)
 {
 	ws_listener *l;
 	int          rv;
-	nni_sock *   s = nni_listener_sock(listener);
+	nni_sock    *s = nni_listener_sock(listener);
 	char         name[64];
 
 	if ((l = NNI_ALLOC_STRUCT(l)) == NULL) {
@@ -713,6 +713,7 @@ static nni_sp_tran wss4_tran = {
 	.tran_fini     = wstran_fini,
 };
 
+#ifdef NNG_ENABLE_IPV6
 static nni_sp_tran wss6_tran = {
 	.tran_scheme   = "wss6",
 	.tran_dialer   = &ws_dialer_ops,
@@ -721,13 +722,16 @@ static nni_sp_tran wss6_tran = {
 	.tran_init     = wstran_init,
 	.tran_fini     = wstran_fini,
 };
+#endif
 
 void
 nni_sp_wss_register(void)
 {
 	nni_sp_tran_register(&wss_tran);
 	nni_sp_tran_register(&wss4_tran);
+#ifdef NNG_ENABLE_IPV6
 	nni_sp_tran_register(&wss6_tran);
+#endif
 }
 
 #endif // NNG_TRANSPORT_WSS