fixes #143 Protocols and transports should be "configurable"

This makes all the protocols and transports optional.  All
of them except ZeroTier are enabled by default, but you can
now disable them (remove from the build) with cmake options.

The test suite is modified so that tests still run as much
as they can, but skip over things caused by missing functionality
from the library (due to configuration).

Further, the constant definitions and prototypes for functions
that are specific to transports or protocols are moved into
appropriate headers, which should be included directly by
applications wishing to use these.

We have also added and improved documentation -- all of the
transports are documented, and several more man pages for
protocols have been added.  (Req/Rep and Surveyor are still
missing.)

4 files changed, 54 insertions, 23 deletions

diff --git a/src/core/msgqueue.c b/src/core/msgqueue.c
index 3f1ffcb5..10bffaa4 100644
--- a/src/core/msgqueue.c
+++ b/src/core/msgqueue.c
@@ -297,7 +297,6 @@ nni_msgq_run_getq(nni_msgq *mq)
 static void
 nni_msgq_run_notify(nni_msgq *mq)
 {
-	nni_aio *aio;
 	if (mq->mq_cb_fn != NULL) {
 		int flags = 0;
 
diff --git a/src/core/protocol.h b/src/core/protocol.h
index 5db259f0..39bde059 100644
--- a/src/core/protocol.h
+++ b/src/core/protocol.h
@@ -147,21 +147,26 @@ extern int nni_proto_open(nng_socket *, const nni_proto *);
 // Protocol numbers are never more than 16 bits.  Also, there will never be
 // a valid protocol numbered 0 (NNG_PROTO_NONE).
 #define NNI_PROTO(major, minor) (((major) *16) + (minor))
-enum nng_proto_enum {
-	NNI_PROTO_NONE          = NNI_PROTO(0, 0),
-	NNI_PROTO_PAIR_V0       = NNI_PROTO(1, 0),
-	NNI_PROTO_PAIR_V1       = NNI_PROTO(1, 1),
-	NNI_PROTO_PUB_V0        = NNI_PROTO(2, 0),
-	NNI_PROTO_SUB_V0        = NNI_PROTO(2, 1),
-	NNI_PROTO_REQ_V0        = NNI_PROTO(3, 0),
-	NNI_PROTO_REP_V0        = NNI_PROTO(3, 1),
-	NNI_PROTO_PUSH_V0       = NNI_PROTO(5, 0),
-	NNI_PROTO_PULL_V0       = NNI_PROTO(5, 1),
-	NNI_PROTO_SURVEYOR_V0   = NNI_PROTO(6, 2),
-	NNI_PROTO_RESPONDENT_V0 = NNI_PROTO(6, 3),
-	NNI_PROTO_BUS_V0        = NNI_PROTO(7, 0),
-	NNI_PROTO_STAR_V0       = NNI_PROTO(100, 0),
-};
+
+// Protocol major numbers.  This is here for documentation only, and
+// to serve as a "registry" for managing new protocol numbers.  Consider
+// updating this table when adding new protocols.
+//
+// Protocol     Maj Min Name       Notes
+// -------------------------------------------
+// NONE          0   0             reserved
+// PAIRv0        1   0  pair
+// PAIRv1        1   1  pair1      nng only, experimental
+// PUBv0         2   0  pub
+// SUBv0         2   1  sub
+// REQv0         3   0  req
+// REPv0         3   1  rep
+// PUSHv0        5   0  push
+// PULLv0        5   1  pull
+// SURVEYORv0    6   2  surveyor   minors 0 & 1 retired
+// RESPONDENTv0  6   3  respondent
+// BUSv0         7   0  bus
+// STARv0      100   0  star       mangos only, experimental
 
 extern int  nni_proto_sys_init(void);
 extern void nni_proto_sys_fini(void);
diff --git a/src/core/socket.c b/src/core/socket.c
index c9b70ccb..4a84b639 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -102,7 +102,6 @@ static int
 nni_sock_getopt_fd(nni_sock *s, int flag, void *val, size_t *szp)
 {
 	int           rv;
-	uint32_t      flags;
 	nni_notifyfd *fd;
 	nni_msgq *    mq;
 	nni_msgq_cb   cb;
diff --git a/src/core/transport.c b/src/core/transport.c
index 6dcf4538..af9c93fb 100644
--- a/src/core/transport.c
+++ b/src/core/transport.c
@@ -10,6 +10,9 @@
 
 #include "core/nng_impl.h"
 #include "transport/inproc/inproc.h"
+#include "transport/ipc/ipc.h"
+#include "transport/tcp/tcp.h"
+#include "transport/zerotier/zerotier.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -51,6 +54,11 @@ nni_tran_register(const nni_tran *tran)
 	nni_mtx_lock(&nni_tran_lk);
 	// Check to see if the transport is already registered...
 	NNI_LIST_FOREACH (&nni_tran_list, t) {
+		if (tran->tran_init == t->t_tran.tran_init) {
+			nni_mtx_unlock(&nni_tran_lk);
+			// Same transport, duplicate registration.
+			return (0);
+		}
 		if (strcmp(tran->tran_scheme, t->t_tran.tran_scheme) == 0) {
 			nni_mtx_unlock(&nni_tran_lk);
 			return (NNG_ESTATE);
@@ -129,20 +137,40 @@ nni_tran_chkopt(const char *name, const void *v, size_t sz)
 
 // nni_tran_sys_init initializes the entire transport subsystem, including
 // each individual transport.
+
+typedef int (*nni_tran_ctor)(void);
+
+static nni_tran_ctor nni_tran_ctors[] = {
+#ifdef NNG_HAVE_INPROC
+	nng_inproc_register,
+#endif
+#ifdef NNG_HAVE_IPC
+	nng_ipc_register,
+#endif
+#ifdef NNG_HAVE_TCP
+	nng_tcp_register,
+#endif
+#ifdef NNI_HAVE_ZEROTIER
+	nng_zt_register,
+#endif
+	NULL,
+};
+
 int
 nni_tran_sys_init(void)
 {
-	int rv;
+	int i;
 
 	nni_tran_inited = 1;
 	NNI_LIST_INIT(&nni_tran_list, nni_transport, t_node);
 	nni_mtx_init(&nni_tran_lk);
 
-	if (((rv = nng_inproc_register()) != 0) ||
-	    ((rv = nni_tran_register(&nni_ipc_tran)) != 0) ||
-	    ((rv = nni_tran_register(&nni_tcp_tran)) != 0)) {
-		nni_tran_sys_fini();
-		return (rv);
+	for (i = 0; nni_tran_ctors[i] != NULL; i++) {
+		int rv;
+		if ((rv = (nni_tran_ctors[i])()) != 0) {
+			nni_tran_sys_fini();
+			return (rv);
+		}
 	}
 	return (0);
 }