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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
* Copyright (c) 2025-present Eclipse ThreadX Contributors
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Component */
/** */
/** Transmission Control Protocol (TCP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_ip.h"
#include "nx_packet.h"
#include "nx_tcp.h"
#include "tx_thread.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_tcp_socket_receive PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function attempts to receive one or more TCP packets from the */
/* specified socket. */
/* */
/* INPUT */
/* */
/* socket_ptr Pointer to socket */
/* packet_ptr Pointer to packet pointer */
/* wait_option Suspension option */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_tcp_packet_send_ack Send ACK message */
/* _nx_tcp_socket_thread_suspend Suspend calling thread */
/* tx_mutex_get Get protection mutex */
/* tx_mutex_put Put protection mutex */
/* */
/* CALLED BY */
/* */
/* Application */
/* */
/**************************************************************************/
UINT _nx_tcp_socket_receive(NX_TCP_SOCKET *socket_ptr, NX_PACKET **packet_ptr, ULONG wait_option)
{
NX_IP *ip_ptr;
NX_TCP_HEADER *header_ptr;
NX_PACKET *head_packet_ptr;
ULONG header_length;
#ifdef TX_ENABLE_EVENT_TRACE
TX_TRACE_BUFFER_ENTRY *trace_event;
ULONG trace_timestamp;
#endif
/* Setup the pointer to the associated IP instance. */
ip_ptr = socket_ptr -> nx_tcp_socket_ip_ptr;
/* Set the return pointer to NULL initially. */
*packet_ptr = NX_NULL;
/* If trace is enabled, insert this event into the trace buffer. */
NX_TRACE_IN_LINE_INSERT(NX_TRACE_TCP_SOCKET_RECEIVE, socket_ptr, 0, 0, 0, NX_TRACE_TCP_EVENTS, &trace_event, &trace_timestamp);
/* Get protection while we look at this socket. */
tx_mutex_get(&(ip_ptr -> nx_ip_protection), TX_WAIT_FOREVER);
/* Determine if the socket is currently bound. */
if (!socket_ptr -> nx_tcp_socket_bound_next)
{
/* Release protection. */
tx_mutex_put(&(ip_ptr -> nx_ip_protection));
/* Socket is not bound, return an error message. */
return(NX_NOT_BOUND);
}
/* Do not return without data if there is data on the queue. */
if (!socket_ptr -> nx_tcp_socket_receive_queue_head)
{
/* There is no data on the queue. */
/* Determine if the socket is still in an active state, but also allow
a receive socket operation if there are still more queued receive
packets for this socket. */
if ((socket_ptr -> nx_tcp_socket_state < NX_TCP_SYN_SENT) ||
(socket_ptr -> nx_tcp_socket_state == NX_TCP_CLOSE_WAIT) ||
(socket_ptr -> nx_tcp_socket_state >= NX_TCP_CLOSING))
{
/* Release the IP protection. */
tx_mutex_put(&(ip_ptr -> nx_ip_protection));
/* Return an error code. */
return(NX_NOT_CONNECTED);
}
}
/* Pickup the important information from the socket. */
/* Attempt to build a pointer to the first packet in the socket's
receive queue. */
if (socket_ptr -> nx_tcp_socket_receive_queue_head)
{
/* Yes, there is a packet on the receive queue. Setup a pointer to it and
its header. */
head_packet_ptr = socket_ptr -> nx_tcp_socket_receive_queue_head;
}
else
{
/* Just set the pointers to NULL. */
head_packet_ptr = NX_NULL;
}
/* Determine if there is a receive packet available. */
/*lint -e{923} suppress cast of ULONT to pointer. */
if ((head_packet_ptr) && (head_packet_ptr -> nx_packet_queue_next == ((NX_PACKET *)NX_PACKET_READY)))
{
/* Yes, the first packet in the queue is available and has been ACKed. Remove it
from the queue and return it to the caller. */
if (head_packet_ptr == socket_ptr -> nx_tcp_socket_receive_queue_tail)
{
/* Only item in the queue. Set the head and tail pointers to NULL. */
socket_ptr -> nx_tcp_socket_receive_queue_head = NX_NULL;
socket_ptr -> nx_tcp_socket_receive_queue_tail = NX_NULL;
}
else
{
/* Simply update the head pointer to the packet after the current. The tail pointer does not
need update. */
socket_ptr -> nx_tcp_socket_receive_queue_head = head_packet_ptr -> nx_packet_union_next.nx_packet_tcp_queue_next;
}
/* Decrease the number of received packets. */
socket_ptr -> nx_tcp_socket_receive_queue_count--;
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
header_ptr = (NX_TCP_HEADER *)head_packet_ptr -> nx_packet_prepend_ptr;
/* Calculate the header size for this packet. */
header_length = (header_ptr -> nx_tcp_header_word_3 >> NX_TCP_HEADER_SHIFT) * (ULONG)sizeof(ULONG);
/* Adjust the packet prepend pointer and length to position past the TCP header. */
head_packet_ptr -> nx_packet_prepend_ptr = head_packet_ptr -> nx_packet_prepend_ptr + header_length;
head_packet_ptr -> nx_packet_length = head_packet_ptr -> nx_packet_length - header_length;
/* Indicate that this TCP packet is no longer enqueued by marking it again as allocated. This is what
it was prior to being part of the TCP receive queue. */
/*lint -e{923} suppress cast of ULONT to pointer. */
head_packet_ptr -> nx_packet_union_next.nx_packet_tcp_queue_next = (NX_PACKET *)NX_PACKET_ALLOCATED;
/* Clear the queue next pointer. */
head_packet_ptr -> nx_packet_queue_next = NX_NULL;
/* Place the packet pointer in the return pointer. */
*packet_ptr = head_packet_ptr;
/* Check the receive queue count. */
if (socket_ptr -> nx_tcp_socket_receive_queue_count == 0)
{
/* Make sure the current receive window is the default window! */
socket_ptr -> nx_tcp_socket_rx_window_current = socket_ptr -> nx_tcp_socket_rx_window_default;
}
else
{
/* Increase the receive window size. */
socket_ptr -> nx_tcp_socket_rx_window_current += (*packet_ptr) -> nx_packet_length;
}
/* Determine if an ACK should be forced out for window update, SWS avoidance algorithm.
RFC1122, Section4.2.3.3, Page97-98. */
if (((socket_ptr -> nx_tcp_socket_rx_window_current - socket_ptr -> nx_tcp_socket_rx_window_last_sent) >= (socket_ptr -> nx_tcp_socket_rx_window_default / 2)) &&
((socket_ptr -> nx_tcp_socket_state == NX_TCP_ESTABLISHED) || (socket_ptr -> nx_tcp_socket_state == NX_TCP_FIN_WAIT_1) || (socket_ptr -> nx_tcp_socket_state == NX_TCP_FIN_WAIT_2)))
{
/* Send a Window Update. */
_nx_tcp_packet_send_ack(socket_ptr, socket_ptr -> nx_tcp_socket_tx_sequence);
}
#ifdef TX_ENABLE_EVENT_TRACE
/* Update the trace event with the status. */
NX_TRACE_EVENT_UPDATE(trace_event, trace_timestamp, NX_TRACE_TCP_SOCKET_RECEIVE, 0, *packet_ptr, (*packet_ptr) -> nx_packet_length, socket_ptr -> nx_tcp_socket_rx_sequence);
#endif /* TX_ENABLE_EVENT_TRACE */
/* Release protection. */
tx_mutex_put(&(ip_ptr -> nx_ip_protection));
/* Return a successful status. */
return(NX_SUCCESS);
}
else if ((wait_option) && (_tx_thread_current_ptr != &(ip_ptr -> nx_ip_thread)))
{
/* Suspend the thread on this socket's receive queue. */
/* Save the return packet pointer address as well. */
_tx_thread_current_ptr -> tx_thread_additional_suspend_info = (void *)packet_ptr;
/* Increment the suspended thread count. */
socket_ptr -> nx_tcp_socket_receive_suspended_count++;
/* Suspend the thread on the receive queue. */
/* Note that the mutex is released inside _nx_tcp_socket_thread_suspend(). */
_nx_tcp_socket_thread_suspend(&(socket_ptr -> nx_tcp_socket_receive_suspension_list), _nx_tcp_receive_cleanup, socket_ptr, &(ip_ptr -> nx_ip_protection), wait_option);
#ifdef TX_ENABLE_EVENT_TRACE
if (*packet_ptr)
{
/* Update the trace event with the status. */
NX_TRACE_EVENT_UPDATE(trace_event, trace_timestamp, NX_TRACE_TCP_SOCKET_RECEIVE, 0, *packet_ptr, (*packet_ptr) -> nx_packet_length, socket_ptr -> nx_tcp_socket_rx_sequence);
}
#endif /* TX_ENABLE_EVENT_TRACE */
/* If not, just return the error code. */
return(_tx_thread_current_ptr -> tx_thread_suspend_status);
}
else
{
/* Release protection. */
tx_mutex_put(&(ip_ptr -> nx_ip_protection));
/* Return an empty receive queue error message. */
return(NX_NO_PACKET);
}
}
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