fixes #168 UDP transport

This is the initial implementation of UDP transport.
It does in order guarantees (and consequently filters duplicates),
but it does not guarantee delivery.  The protocol limits payloads
to 65000 bytes (minus headers for SP), but you really want to
keep it to much less -- probably best for short messages that within
a single MTU to avoid IP fragmentation and reassembly.

This is unicast only for now (although there are plans for some
support for multicast and broadcast as well as being able to
perform automatic mesh building, but that will be in following work.

Additional tunables are coming.  This is only lightly tested at
this point, and should be considered experimental.  Its also undocumented.

cmake/NNGOptions.cmake

@@ -135,6 +135,9 @@ mark_as_advanced(NNG_TRANSPORT_WSS)
 option (NNG_TRANSPORT_FDC "Enable File Descriptor transport (EXPERIMENTAL)" ON)
 mark_as_advanced(NNG_TRANSPORT_FDC)
 
+option (NNG_TRANSPORT_UDP "Enable UDP transport (EXPERIMENTAL)" ON)
+mark_as_advanced(NNG_TRANSPORT_UDP)
+
 # ZeroTier
 option (NNG_TRANSPORT_ZEROTIER "Enable ZeroTier transport (requires libzerotiercore)." OFF)
 mark_as_advanced(NNG_TRANSPORT_ZEROTIER)

src/core/aio.c

@@ -8,6 +8,8 @@
 // found online at https://opensource.org/licenses/MIT.
 //
 
+#include "core/defs.h"
+#include "nng/nng.h"
 #include "nng_impl.h"
 
 #include <string.h>
@@ -764,7 +766,16 @@ nni_sleep_aio(nng_duration ms, nng_aio *aio)
 			ms               = aio->a_timeout;
 		}
 	}
-	aio->a_expire = nni_clock() + ms;
+	switch (ms) {
+	case NNG_DURATION_INFINITE:
+	case NNG_DURATION_DEFAULT:
+		// infinite sleep
+		aio->a_expire = NNI_TIME_NEVER;
+		break;
+	default:
+		aio->a_expire = nni_clock() + ms;
+		break;
+	}
 
 	if ((rv = nni_aio_schedule(aio, nni_sleep_cancel, NULL)) != 0) {
 		nni_aio_finish_error(aio, rv);

src/core/idhash.c

@@ -389,3 +389,9 @@ nni_id_visit(nni_id_map *m, uint64_t *keyp, void **valp, uint32_t *cursor)
 	*cursor = index;
 	return (false);
 }
+
+uint32_t
+nni_id_count(const nni_id_map *m)
+{
+	return (m->id_count);
+}

src/core/idhash.h

@@ -46,15 +46,16 @@ struct nni_id_map {
 #define NNI_ID_FLAG_RANDOM 2   // start at a random value
 #define NNI_ID_FLAG_REGISTER 4 // map is registered for finalization
 
-extern void  nni_id_map_init(nni_id_map *, uint64_t, uint64_t, bool);
-extern void  nni_id_map_fini(nni_id_map *);
-extern void *nni_id_get(nni_id_map *, uint64_t);
-extern int   nni_id_set(nni_id_map *, uint64_t, void *);
-extern int   nni_id_alloc(nni_id_map *, uint64_t *, void *);
-extern int   nni_id_alloc32(nni_id_map *, uint32_t *, void *);
-extern int   nni_id_remove(nni_id_map *, uint64_t);
-extern void  nni_id_map_sys_fini(void);
-extern bool  nni_id_visit(nni_id_map *, uint64_t *, void **, uint32_t *);
+extern void     nni_id_map_init(nni_id_map *, uint64_t, uint64_t, bool);
+extern void     nni_id_map_fini(nni_id_map *);
+extern void    *nni_id_get(nni_id_map *, uint64_t);
+extern int      nni_id_set(nni_id_map *, uint64_t, void *);
+extern int      nni_id_alloc(nni_id_map *, uint64_t *, void *);
+extern int      nni_id_alloc32(nni_id_map *, uint32_t *, void *);
+extern int      nni_id_remove(nni_id_map *, uint64_t);
+extern void     nni_id_map_sys_fini(void);
+extern bool     nni_id_visit(nni_id_map *, uint64_t *, void **, uint32_t *);
+extern uint32_t nni_id_count(const nni_id_map *);
 
 #define NNI_ID_MAP_INITIALIZER(min, max, flags)            \
 	{                                                  \

src/core/message.c

@@ -29,6 +29,7 @@ struct nng_msg {
 	nni_chunk      m_body;
 	uint32_t       m_pipe; // set on receive
 	nni_atomic_int m_refcnt;
+	nng_sockaddr   m_addr; // set on receive, transport use
 };
 
 #if 0
@@ -544,6 +545,16 @@ nni_msg_chop(nni_msg *m, size_t len)
 	return (nni_chunk_chop(&m->m_body, len));
 }
 
+// Grow the message header, but don't put anything there.
+// This is useful for setting up to receive directly into it
+// for zero copy purposes.
+void
+nni_msg_header_extend(nni_msg *m, size_t len)
+{
+	NNI_ASSERT((len + m->m_header_len) <= sizeof(m->m_header_buf));
+	m->m_header_len += len;
+}
+
 int
 nni_msg_header_append(nni_msg *m, const void *data, size_t len)
 {
@@ -656,3 +667,15 @@ nni_msg_get_pipe(const nni_msg *m)
 {
 	return (m->m_pipe);
 }
+
+const nng_sockaddr *
+nni_msg_address(const nni_msg *msg)
+{
+	return (&msg->m_addr);
+}
+
+void
+nni_msg_set_address(nng_msg *msg, const nng_sockaddr *addr)
+{
+	msg->m_addr = *addr;
+}

src/core/message.h

@@ -1,5 +1,5 @@
 //
-// Copyright 2021 Staysail Systems, Inc. <[email protected]>
+// Copyright 2024 Staysail Systems, Inc. <[email protected]>
 // Copyright 2017 Capitar IT Group BV <[email protected]>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -20,9 +20,9 @@ extern int      nni_msg_realloc(nni_msg *, size_t);
 extern int      nni_msg_reserve(nni_msg *, size_t);
 extern size_t   nni_msg_capacity(nni_msg *);
 extern int      nni_msg_dup(nni_msg **, const nni_msg *);
-extern void *   nni_msg_header(nni_msg *);
+extern void    *nni_msg_header(nni_msg *);
 extern size_t   nni_msg_header_len(const nni_msg *);
-extern void *   nni_msg_body(nni_msg *);
+extern void    *nni_msg_body(nni_msg *);
 extern size_t   nni_msg_len(const nni_msg *);
 extern int      nni_msg_append(nni_msg *, const void *, size_t);
 extern int      nni_msg_insert(nni_msg *, const void *, size_t);
@@ -55,6 +55,14 @@ extern void     nni_msg_clone(nni_msg *);
 extern nni_msg *nni_msg_unique(nni_msg *);
 extern bool     nni_msg_shared(nni_msg *);
 
+// Socket address access. Principally useful for transports like UDP,
+// which may need to remember or add the socket address later.
+// SP transports will generally not support upper layers setting the
+// address on send, but will take the information from the pipe.
+// It may be set on receive, depending upon the transport.
+extern const nng_sockaddr *nni_msg_address(const nni_msg *);
+extern void nni_msg_set_address(nng_msg *, const nng_sockaddr *);
+
 // nni_msg_pull_up ensures that the message is unique, and that any
 // header present is "pulled up" into the message body.  If the function
 // cannot do this for any reason (out of space in the body), then NULL

src/core/platform.h

@@ -356,7 +356,7 @@ extern int nni_tcp_listener_get(
 // 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 *);
+    const char *, const char *, uint16_t, 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 *);

src/core/url.c

@@ -8,6 +8,7 @@
 // found online at https://opensource.org/licenses/MIT.
 //
 
+#include "nng/nng.h"
 #include "nng_impl.h"
 
 #include <ctype.h>
@@ -277,6 +278,32 @@ nni_url_default_port(const char *scheme)
 	return ("");
 }
 
+// Return the address family for an address scheme.
+// Returns NNG_AF_UNSPEC for unknown cases or where
+// we do not want to choose between AF_INET and AF_INET6.
+uint16_t
+nni_url_family(const char *scheme)
+{
+	if (strcmp(scheme, "ipc") == 0) {
+		return (NNG_AF_IPC);
+	}
+	if (strcmp(scheme, "inproc") == 0) {
+		return (NNG_AF_INPROC);
+	}
+	if (strcmp(scheme, "abstract") == 0) {
+		return (NNG_AF_ABSTRACT);
+	}
+#ifdef NNG_HAVE_INET6
+	if (strchr(scheme, '6') != NULL) {
+		return (NNG_AF_INET6);
+	}
+#endif
+	if (strchr(scheme, '4') != NULL) {
+		return (NNG_AF_INET);
+	}
+	return (NNG_AF_UNSPEC);
+}
+
 // URLs usually follow the following format:
 //
 // scheme:[//[userinfo@]host][/]path[?query][#fragment]
@@ -600,7 +627,7 @@ nni_url_clone(nni_url **dstp, const nni_url *src)
 // nni_url_to_address resolves a URL into a sockaddr, assuming the URL is for
 // an IP address.
 int
-nni_url_to_address(nng_sockaddr *sa, const nng_url *url)
+nni_url_to_address(nng_sockaddr *sa, const nni_url *url)
 {
 	int         af;
 	nni_aio     aio;

src/core/url.h

@@ -17,6 +17,7 @@ extern int         nni_url_parse(nni_url **, const char *path);
 extern void        nni_url_free(nni_url *);
 extern int         nni_url_clone(nni_url **, const nni_url *);
 extern const char *nni_url_default_port(const char *);
+extern uint16_t    nni_url_family(const char *);
 extern int         nni_url_asprintf(char **, const nni_url *);
 extern int         nni_url_asprintf_port(char **, const nni_url *, int);
 extern size_t      nni_url_decode(uint8_t *, const char *, size_t);

src/platform/posix/posix_resolv_gai.c

@@ -236,7 +236,7 @@ resolv_task(resolv_item *item)
 }
 
 void
-nni_resolv_ip(const char *host, const char *serv, int af, bool passive,
+nni_resolv_ip(const char *host, const char *serv, uint16_t af, bool passive,
     nng_sockaddr *sa, nni_aio *aio)
 {
 	resolv_item *item;

src/platform/posix/posix_udp.c

@@ -9,8 +9,8 @@
 //
 
 #include "core/nng_impl.h"
-#include "nng/nng.h"
 #include "platform/posix/posix_impl.h"
+#include <nng/nng.h>
 #include <sys/errno.h>
 
 #ifdef NNG_PLATFORM_POSIX

src/sp/transport.c

@@ -75,6 +75,9 @@ extern void nni_sp_zt_register(void);
 #ifdef NNG_TRANSPORT_FDC
 extern void nni_sp_sfd_register(void);
 #endif
+#ifdef NNG_TRANSPORT_UDP
+extern void nni_sp_udp_register(void);
+#endif
 
 void
 nni_sp_tran_sys_init(void)
@@ -103,6 +106,9 @@ nni_sp_tran_sys_init(void)
 #ifdef NNG_TRANSPORT_FDC
 	nni_sp_sfd_register();
 #endif
+#ifdef NNG_TRANSPORT_UDP
+	nni_sp_udp_register();
+#endif
 }
 
 // nni_sp_tran_sys_fini finalizes the entire transport system, including all

src/sp/transport/CMakeLists.txt

@@ -1,5 +1,5 @@
 #
-# Copyright 2023 Staysail Systems, Inc. <[email protected]>
+# Copyright 2024 Staysail Systems, Inc. <[email protected]>
 #
 # This software is supplied under the terms of the MIT License, a
 # copy of which should be located in the distribution where this
@@ -17,4 +17,4 @@ add_subdirectory(tcp)
 add_subdirectory(tls)
 add_subdirectory(ws)
 add_subdirectory(zerotier)
-
+add_subdirectory(udp)

src/sp/transport/tcp/tcp.c

@@ -730,7 +730,7 @@ tcptran_ep_close(void *arg)
 static int
 tcptran_url_parse_source(nng_url *url, nng_sockaddr *sa, const nng_url *surl)
 {
-	int      af;
+	uint16_t af;
 	char    *semi;
 	char    *src;
 	size_t   len;
@@ -751,18 +751,7 @@ tcptran_url_parse_source(nng_url *url, nng_sockaddr *sa, const nng_url *surl)
 
 	len             = (size_t) (semi - url->u_hostname);
 	url->u_hostname = semi + 1;
-
-	if (strcmp(surl->u_scheme, "tcp") == 0) {
-		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);
-	}
+	af              = nni_url_family(url->u_scheme);
 
 	if ((src = nni_alloc(len + 1)) == NULL) {
 		return (NNG_ENOMEM);

src/sp/transport/tls/tls.c

@@ -712,18 +712,9 @@ tlstran_url_parse_source(nni_url *url, nng_sockaddr *sa, const nni_url *surl)
 
 	len             = (size_t) (semi - url->u_hostname);
 	url->u_hostname = semi + 1;
+	af              = nni_url_family(url->u_scheme);
 
-	if (strcmp(surl->u_scheme, "tls+tcp") == 0) {
-		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);
-	}
+	rv = nni_url_to_address(sa, url);
 
 	if ((src = nni_alloc(len + 1)) == NULL) {
 		return (NNG_ENOMEM);

src/sp/transport/udp/CMakeLists.txt

@@ -0,0 +1,15 @@
+#
+# Copyright 2024 Staysail Systems, Inc. <[email protected]>
+#
+# This software is supplied under the terms of the MIT License, a
+# copy of which should be located in the distribution where this
+# file was obtained (LICENSE.txt).  A copy of the license may also be
+# found online at https://opensource.org/licenses/MIT.
+#
+
+# UDP transport
+nng_directory(udp)
+
+nng_sources_if(NNG_TRANSPORT_UDP udp.c)
+nng_defines_if(NNG_TRANSPORT_UDP NNG_TRANSPORT_UDP)
+nng_test_if(NNG_TRANSPORT_UDP udp_tran_test)