Networking: Fix some errors found by Coverity

net/inet/inet_sockif.c

@@ -615,9 +615,10 @@ int inet_listen(FAR struct socket *psock, int backlog)
  *   an address with the sa_family member of sockaddr set to AF_UNSPEC.
  *
  * Parameters:
- *   psock     Pointer to a socket structure initialized by psock_socket()
- *   addr      Server address (form depends on type of socket)
- *   addrlen   Length of actual 'addr'
+ *   psock   - Pointer to a socket structure initialized by psock_socket()
+ *   addr    - Server address (form depends on type of socket).  The upper
+ *             socket layer has verified that this address is non-NULL.
+ *   addrlen - Length of actual 'addr'
  *
  * Returned Value:
  *   0 on success; a negated errno value on failue.  See connect() for the
@@ -685,7 +686,7 @@ static int inet_connect(FAR struct socket *psock,
       case SOCK_DGRAM:
         {
           int ret = udp_connect(psock->s_conn, addr);
-          if (ret < 0 || addr == NULL)
+          if (ret < 0)
             {
               psock->s_flags &= ~_SF_CONNECTED;
             }

net/inet/ipv4_getsockname.c

@@ -98,6 +98,7 @@ int ipv4_getsockname(FAR struct socket *psock, FAR struct sockaddr *addr,
       return -ENOSYS;
     }
 
+#if defined(NET_TCP_HAVE_STACK) || defined(NET_UDP_HAVE_STACK)
   /* Set the port number */
 
   switch (psock->s_type)
@@ -170,6 +171,9 @@ int ipv4_getsockname(FAR struct socket *psock, FAR struct sockaddr *addr,
   /* Return success */
 
   return OK;
+#else
+  return -EOPNOTSUPP;
+#endif
 }
 
 #endif /* CONFIG_NET_IPv4 */

net/socket/connect.c

@@ -145,6 +145,14 @@ int psock_connect(FAR struct socket *psock, FAR const struct sockaddr *addr,
       goto errout;
     }
 
+  /* Make sure that an address was provided */
+
+  if (addr == NULL)
+    {
+      errcode = EFAULT;
+      goto errout;
+    }
+
   /* Let the address family's connect() method handle the operation */
 
   DEBUGASSERT(psock->s_sockif != NULL && psock->s_sockif->si_connect != NULL);

net/tcp/tcp_conn.c

@@ -890,7 +890,7 @@ FAR struct tcp_conn_s *tcp_alloc_accept(FAR struct net_driver_s *dev,
 
   /* Get the appropriate IP domain */
 
-#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv4)
+#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
   bool ipv6 = IFF_IS_IPv6(dev->d_flags);
   domain = ipv6 ? PF_INET6 : PF_INET;
 #elif defined(CONFIG_NET_IPv4)