Use a named constant for "random port number"

Signed-off-by: Erik Boasson <[email protected]>
eclipse-cyclonedds · Jul 27, 2023 · aee37ee · aee37ee
1 parent 5fde54e
commit aee37ee
Show file tree

Hide file tree

Showing 4 changed files with 20 additions and 10 deletions.
diff --git a/src/core/ddsi/src/ddsi__tran.h b/src/core/ddsi/src/ddsi__tran.h
@@ -33,6 +33,12 @@ struct ddsi_domaingv;
 /* Flags */
 #define DDSI_TRAN_ON_CONNECT 0x0001
 
+/* Magic value for port number argument in create_conn and create_listener to indicate
+   that a random port number is requested.  Note that 0 also happens to be illegal in UDP
+   and TCP and is DDSI_LOCATOR_PORT_INVALID in the DDSI spec.  What a fortunate
+   coincidence!  */
+#define DDSI_TRAN_RANDOM_PORT_NUMBER 0
+
 enum ddsi_tran_qos_purpose {
   DDSI_TRAN_QOS_XMIT_UC, // will send unicast only
   DDSI_TRAN_QOS_XMIT_MC, // may send unicast or multicast
@@ -252,15 +258,15 @@ inline dds_return_t ddsi_factory_create_conn (struct ddsi_tran_conn **conn, stru
   *conn = NULL;
   if ((qos->m_interface != NULL) != (qos->m_purpose == DDSI_TRAN_QOS_XMIT_UC || qos->m_purpose == DDSI_TRAN_QOS_XMIT_MC))
     return DDS_RETCODE_BAD_PARAMETER;
-  if (port != 0 && !ddsi_is_valid_port (factory, port))
+  if (port != DDSI_TRAN_RANDOM_PORT_NUMBER && !ddsi_is_valid_port (factory, port))
     return DDS_RETCODE_BAD_PARAMETER;
   return factory->m_create_conn_fn (conn, factory, port, qos);
 }
 
 /** @component transport */
 inline dds_return_t ddsi_factory_create_listener (struct ddsi_tran_listener **listener, struct ddsi_tran_factory * factory, uint32_t port, const struct ddsi_tran_qos *qos) {
   *listener = NULL;
-  if (port != 0 && !ddsi_is_valid_port (factory, port))
+  if (port != DDSI_TRAN_RANDOM_PORT_NUMBER && !ddsi_is_valid_port (factory, port))
     return DDS_RETCODE_BAD_PARAMETER;
   return factory->m_create_listener_fn (listener, factory, port, qos);
 }

diff --git a/src/core/ddsi/src/ddsi_debmon.c b/src/core/ddsi/src/ddsi_debmon.c
@@ -711,7 +711,7 @@ struct ddsi_debug_monitor *ddsi_new_debug_monitor (struct ddsi_domaingv *gv, int
   if ((dm->tran_factory = ddsi_factory_find (gv, "tcp")) == NULL)
     dm->tran_factory = ddsi_factory_find (gv, "tcp6");
 
-  if (port != 0 && !ddsi_is_valid_port (dm->tran_factory, (uint32_t) port))
+  if (port != DDSI_TRAN_RANDOM_PORT_NUMBER && !ddsi_is_valid_port (dm->tran_factory, (uint32_t) port))
   {
     GVERROR ("debug monitor port number %"PRId32" is invalid\n", port);
     goto err_invalid_port;

diff --git a/src/core/ddsi/src/ddsi_init.c b/src/core/ddsi/src/ddsi_init.c
@@ -112,9 +112,9 @@ static enum make_uc_sockets_ret make_uc_sockets (struct ddsi_domaingv *gv, uint3
   *pdisc = ddsi_get_port (&gv->config, DDSI_PORT_UNI_DISC, ppid);
   *pdata = ddsi_get_port (&gv->config, DDSI_PORT_UNI_DATA, ppid);
 
-  if (*pdisc != 0 && !ddsi_is_valid_port (gv->m_factory, *pdisc))
+  if (*pdisc != DDSI_TRAN_RANDOM_PORT_NUMBER && !ddsi_is_valid_port (gv->m_factory, *pdisc))
     return MUSRET_INVALID_PORTS;
-  if (*pdata != 0 && !ddsi_is_valid_port (gv->m_factory, *pdata))
+  if (*pdata != DDSI_TRAN_RANDOM_PORT_NUMBER && !ddsi_is_valid_port (gv->m_factory, *pdata))
     return MUSRET_INVALID_PORTS;
 
   const struct ddsi_tran_qos qos = { .m_purpose = DDSI_TRAN_QOS_RECV_UC, .m_diffserv = 0, .m_interface = NULL };
@@ -285,7 +285,7 @@ static int string_to_default_locator (const struct ddsi_domaingv *gv, ddsi_locat
       GVERROR ("%s: invalid address kind (%s)\n", string, tag);
       return -1;
   }
-  if (port != 0 && !ddsi_is_unspec_locator(loc))
+  if (port != DDSI_LOCATOR_PORT_INVALID && !ddsi_is_unspec_locator(loc))
     loc->port = port;
   else
     loc->port = DDSI_LOCATOR_PORT_INVALID;
@@ -1492,8 +1492,8 @@ int ddsi_init (struct ddsi_domaingv *gv)
   else
   {
     if (gv->config.tcp_port < 0)
-      ; /* nop */
-    else if (gv->config.tcp_port == 0)
+      ; /* no TCP listener */
+    else if (gv->config.tcp_port == DDSI_TRAN_RANDOM_PORT_NUMBER)
       ; /* kernel-allocated random port */
     else if (!ddsi_is_valid_port (gv->m_factory, (uint32_t) gv->config.tcp_port))
     {

diff --git a/src/core/ddsi/src/ddsi_portmapping.c b/src/core/ddsi/src/ddsi_portmapping.c
@@ -15,6 +15,9 @@
 #include "dds/ddsi/ddsi_config.h"
 #include "ddsi__portmapping.h"
 
+// for a static assert on DDSI_TRAN_RANDOM_PORT_NUMBER
+#include "ddsi__tran.h"
+
 static bool get_port_int (uint32_t *port, const struct ddsi_portmapping *map, enum ddsi_port which, uint32_t domain_id, int32_t participant_index, char *str_if_overflow, size_t strsize)
 {
   uint32_t off = UINT32_MAX, ppidx = UINT32_MAX;
@@ -38,7 +41,7 @@ static bool get_port_int (uint32_t *port, const struct ddsi_portmapping *map, en
       if (participant_index == DDSI_PARTICIPANT_INDEX_NONE)
       {
         /* participant index "none" means unicast ports get chosen by the transport */
-        *port = 0;
+        *port = DDSI_TRAN_RANDOM_PORT_NUMBER;
         return true;
       }
       off = map->d1;
@@ -48,7 +51,7 @@ static bool get_port_int (uint32_t *port, const struct ddsi_portmapping *map, en
       if (participant_index == DDSI_PARTICIPANT_INDEX_NONE)
       {
         /* participant index "none" means unicast ports get chosen by the transport */
-        *port = 0;
+        *port = DDSI_TRAN_RANDOM_PORT_NUMBER;
         return true;
       }
       off = map->d3;
@@ -62,6 +65,7 @@ static bool get_port_int (uint32_t *port, const struct ddsi_portmapping *map, en
   /* For the mapping to be valid, the port number must be in range of an unsigned 32 bit integer and must
      not be 0 (as that is used for indicating a random port should be selected by the transport).  The
      transports may limit this further, but at least we won't have to worry about overflow anymore. */
+  DDSRT_STATIC_ASSERT (DDSI_TRAN_RANDOM_PORT_NUMBER == 0);
   *port = (uint32_t) (a + b);
   if (a <= UINT32_MAX && b <= UINT32_MAX - a && *port > 0)
     return true;