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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Component */
/** */
/** Transmission Control Protocol (TCP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_tcp.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_tcp_free_port_find PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function finds the first available TCP port, starting from the */
/* supplied port. If no available ports are found, an error is */
/* returned. */
/* */
/* INPUT */
/* */
/* ip_ptr IP instance pointer */
/* port Starting port */
/* free_port_ptr Pointer to return free port */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* tx_mutex_get Obtain protection mutex */
/* tx_mutex_put Release protection mutex */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Yuxin Zhou Initial Version 6.0 */
/* 09-30-2020 Yuxin Zhou Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _nx_tcp_free_port_find(NX_IP *ip_ptr, UINT port, UINT *free_port_ptr)
{
UINT index;
UINT bound;
UINT starting_port;
NX_TCP_SOCKET *search_ptr;
NX_TCP_SOCKET *end_ptr;
#ifdef TX_ENABLE_EVENT_TRACE
TX_TRACE_BUFFER_ENTRY *trace_event;
ULONG trace_timestamp;
#endif
/* If trace is enabled, insert this event into the trace buffer. */
NX_TRACE_IN_LINE_INSERT(NX_TRACE_TCP_FREE_PORT_FIND, ip_ptr, port, 0, 0, NX_TRACE_TCP_EVENTS, &trace_event, &trace_timestamp);
/* Save the original port. */
starting_port = port;
/* Loop through the TCP ports until a free entry is found. */
do
{
/* Calculate the hash index in the TCP port array of the associated IP instance. */
index = (UINT)((port + (port >> 8)) & NX_TCP_PORT_TABLE_MASK);
/* Obtain the IP mutex so we can figure out whether or not the port has already
been bound to. */
tx_mutex_get(&(ip_ptr -> nx_ip_protection), TX_WAIT_FOREVER);
/* Pickup the head of the TCP ports bound list. */
search_ptr = ip_ptr -> nx_ip_tcp_port_table[index];
/* Set the bound flag to false. */
bound = NX_FALSE;
/* Determine if we need to perform a list search. */
if (search_ptr)
{
/* Walk through the circular list of TCP sockets that are already
bound. */
end_ptr = search_ptr;
do
{
/* Determine if this entry is the same as the requested port. */
if (search_ptr -> nx_tcp_socket_port == port)
{
/* Set the bound flag. */
bound = NX_TRUE;
/* Get out of the loop. */
break;
}
/* Move to the next entry in the list. */
search_ptr = search_ptr -> nx_tcp_socket_bound_next;
} while (search_ptr != end_ptr);
}
#ifdef NX_NAT_ENABLE
if (bound == NX_FALSE)
{
/* Check if this IP interface has a NAT service. */
if (ip_ptr -> nx_ip_nat_port_verify)
{
/* Yes, so check the port by NAT handler. If NAT does not use this port, allow NetX to use it. */
bound = (ip_ptr -> nx_ip_nat_port_verify)(ip_ptr, NX_PROTOCOL_TCP, port);
}
}
#endif
/* Release protection. */
tx_mutex_put(&(ip_ptr -> nx_ip_protection));
/* Determine if the port is available. */
if (!bound)
{
/* Setup the return port number. */
*free_port_ptr = port;
/* Update the trace event with the status. */
NX_TRACE_EVENT_UPDATE(trace_event, trace_timestamp, NX_TRACE_TCP_FREE_PORT_FIND, 0, 0, port, 0);
/* Return success. */
return(NX_SUCCESS);
}
/* Move to the next port. */
port++;
/* Determine if we need to wrap. */
if (port > NX_MAX_PORT)
{
/* Yes, we need to wrap around. */
port = NX_SEARCH_PORT_START;
}
} while (starting_port != port);
/* A free port was not found, return an error. */
return(NX_NO_FREE_PORTS);
}