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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"
#ifdef FEATURE_NX_IPV6
#include "nx_ipv6.h"
#endif /* FEATURE_NX_IPV6 */
#include "nx_packet.h"
#include "nx_tcp.h"
#ifdef NX_IPSEC_ENABLE
#include "nx_ipsec.h"
#endif /* NX_IPSEC_ENABLE */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_tcp_packet_send_control PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function sends a TCP control packet from the specified socket. */
/* */
/* INPUT */
/* */
/* socket_ptr Pointer to socket */
/* control_bits TCP control bits */
/* tx_sequence Transmit sequence number */
/* ack_number Transmit acknowledge number */
/* data Data of zero window probe */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _nx_packet_allocate Allocate a packet */
/* _nx_ip_checksum_compute Calculate TCP checksum */
/* _nx_ip_packet_send Send IPv4 packet */
/* _nx_ipv6_packet_send Send IPv6 packet */
/* */
/* CALLED BY */
/* */
/* _nx_tcp_packet_send_syn Send SYN packet */
/* _nx_tcp_packet_send_ack Send ACK packet */
/* _nx_tcp_packet_send_fin Send FIN packet */
/* _nx_tcp_packet_send_rst Send RST packet */
/* _nx_tcp_packet_send_probe Send zero window probe packet */
/* */
/**************************************************************************/
VOID _nx_tcp_packet_send_control(NX_TCP_SOCKET *socket_ptr, ULONG control_bits, ULONG tx_sequence,
ULONG ack_number, ULONG option_word_1, ULONG option_word_2, UCHAR *data)
{
NX_IP *ip_ptr;
NX_PACKET *packet_ptr;
NX_TCP_HEADER *tcp_header_ptr;
ULONG checksum;
ULONG data_offset = 0;
ULONG *source_ip = NX_NULL, *dest_ip = NX_NULL;
#if defined(NX_DISABLE_TCP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
UINT compute_checksum = 1;
#endif /* defined(NX_DISABLE_TCP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
ULONG header_size;
ULONG window_size;
#ifdef NX_DISABLE_TCP_TX_CHECKSUM
compute_checksum = 0;
#endif /* NX_DISABLE_TCP_TX_CHECKSUM */
/* Setup the IP pointer. */
ip_ptr = socket_ptr -> nx_tcp_socket_ip_ptr;
if (control_bits & NX_TCP_SYN_BIT)
{
/* Set header size. */
header_size = NX_TCP_SYN_HEADER;
window_size = socket_ptr -> nx_tcp_socket_rx_window_current;
}
else
{
/* Set header size. */
header_size = NX_TCP_HEADER_SIZE;
/* Set window size. */
#ifdef NX_ENABLE_TCP_WINDOW_SCALING
window_size = socket_ptr -> nx_tcp_socket_rx_window_current >> socket_ptr -> nx_tcp_rcv_win_scale_value;
#else
window_size = socket_ptr -> nx_tcp_socket_rx_window_current;
#endif /* NX_ENABLE_TCP_WINDOW_SCALING */
}
#ifdef NX_ENABLE_TCP_WINDOW_SCALING
/* Make sure the window_size is less than 0xFFFF. */
if (window_size > 0xFFFF)
{
window_size = 0xFFFF;
}
#endif /* NX_ENABLE_TCP_WINDOW_SCALING */
#ifdef NX_IPSEC_ENABLE
/* Get data offset from socket directly. */
data_offset = socket_ptr -> nx_tcp_socket_egress_sa_data_offset;
#endif /* NX_IPSEC_ENABLE */
#ifdef NX_ENABLE_DUAL_PACKET_POOL
/* Allocate from auxiliary packet pool first. */
if (_nx_packet_allocate(ip_ptr -> nx_ip_auxiliary_packet_pool, &packet_ptr, NX_IP_PACKET + data_offset, NX_NO_WAIT))
{
if (ip_ptr -> nx_ip_auxiliary_packet_pool != ip_ptr -> nx_ip_default_packet_pool)
#endif /* NX_ENABLE_DUAL_PACKET_POOL */
{
/*lint -e{835} -e{845} suppress operating on zero. */
if (_nx_packet_allocate(ip_ptr -> nx_ip_default_packet_pool,
&packet_ptr, NX_IP_PACKET + data_offset, NX_NO_WAIT) != NX_SUCCESS)
{
/* Just give up and return. */
return;
}
}
#ifdef NX_ENABLE_DUAL_PACKET_POOL
else
{
/* Just give up and return. */
return;
}
}
#endif /* NX_ENABLE_DUAL_PACKET_POOL */
#ifdef NX_ENABLE_VLAN
if (socket_ptr -> nx_tcp_socket_vlan_priority != NX_VLAN_PRIORITY_INVALID)
{
packet_ptr -> nx_packet_vlan_priority = socket_ptr -> nx_tcp_socket_vlan_priority;
}
#endif /* NX_ENABLE_VLAN */
/* Check to see if the packet has enough room to fill with the max TCP header (SYN + probe data). */
if ((UINT)(packet_ptr -> nx_packet_data_end - packet_ptr -> nx_packet_prepend_ptr) < (NX_TCP_SYN_SIZE + 1))
{
/* Error getting packet, so just get out! */
_nx_packet_release(packet_ptr);
return;
}
/*lint -e{644} suppress variable might not be initialized, since "packet_ptr" was initialized in _nx_packet_allocate. */
packet_ptr -> nx_packet_ip_version = (UCHAR)(socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version);
/* Allocate a packet for the control message. */
#ifndef NX_DISABLE_IPV4
if (socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version == NX_IP_VERSION_V4)
{
/* The outgoing interface should have been stored in the socket structure. */
packet_ptr -> nx_packet_address.nx_packet_interface_ptr = socket_ptr -> nx_tcp_socket_connect_interface;
}
#endif /* !NX_DISABLE_IPV4 */
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, packet_ptr);
#ifdef NX_IPSEC_ENABLE
packet_ptr -> nx_packet_ipsec_sa_ptr = socket_ptr -> nx_tcp_socket_egress_sa;
#endif
/* Setup the packet payload pointers and length for a basic TCP packet. */
packet_ptr -> nx_packet_append_ptr = packet_ptr -> nx_packet_prepend_ptr + sizeof(NX_TCP_HEADER);
/* Setup the packet length. */
packet_ptr -> nx_packet_length = sizeof(NX_TCP_HEADER);
/* Pickup the pointer to the head of the TCP packet. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
tcp_header_ptr = (NX_TCP_HEADER *)packet_ptr -> nx_packet_prepend_ptr;
/* Build the control request in the TCP header. */
tcp_header_ptr -> nx_tcp_header_word_0 = (((ULONG)(socket_ptr -> nx_tcp_socket_port)) << NX_SHIFT_BY_16) | (ULONG)socket_ptr -> nx_tcp_socket_connect_port;
tcp_header_ptr -> nx_tcp_sequence_number = tx_sequence;
tcp_header_ptr -> nx_tcp_acknowledgment_number = ack_number;
tcp_header_ptr -> nx_tcp_header_word_3 = header_size | control_bits | window_size;
tcp_header_ptr -> nx_tcp_header_word_4 = 0;
/* Remember the last ACKed sequence and the last reported window size. */
socket_ptr -> nx_tcp_socket_rx_sequence_acked = ack_number;
socket_ptr -> nx_tcp_socket_rx_window_last_sent = socket_ptr -> nx_tcp_socket_rx_window_current;
/* Endian swapping logic. If NX_LITTLE_ENDIAN is specified, these macros will
swap the endian of the TCP header. */
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_header_word_0);
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_sequence_number);
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_acknowledgment_number);
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_header_word_3);
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_header_word_4);
/* Check whether or not data is set. */
if (data)
{
/* Zero window probe data exist. */
*packet_ptr -> nx_packet_append_ptr++ = *data;
packet_ptr -> nx_packet_length++;
}
/* Whether it is a SYN packet. */
if (control_bits & NX_TCP_SYN_BIT)
{
/* Endian swapping logic. If NX_LITTLE_ENDIAN is specified, these macros will
swap the endian of the TCP header. */
NX_CHANGE_ULONG_ENDIAN(option_word_1);
NX_CHANGE_ULONG_ENDIAN(option_word_2);
/* Set options. */
/*lint --e{927} --e{826} suppress cast of pointer to pointer, since it is necessary */
*((ULONG *)packet_ptr -> nx_packet_append_ptr) = option_word_1;
*(((ULONG *)packet_ptr -> nx_packet_append_ptr) + 1) = option_word_2;
/* Adjust packet information. */
packet_ptr -> nx_packet_append_ptr += (sizeof(ULONG) << 1);
packet_ptr -> nx_packet_length += (ULONG)(sizeof(ULONG) << 1);
}
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
if (socket_ptr -> nx_tcp_socket_connect_interface -> nx_interface_capability_flag & NX_INTERFACE_CAPABILITY_TCP_TX_CHECKSUM)
{
compute_checksum = 0;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
#ifdef NX_IPSEC_ENABLE
if ((packet_ptr -> nx_packet_ipsec_sa_ptr != NX_NULL) && (((NX_IPSEC_SA *)(packet_ptr -> nx_packet_ipsec_sa_ptr)) -> nx_ipsec_sa_encryption_method != NX_CRYPTO_NONE))
{
compute_checksum = 1;
}
#endif /* NX_IPSEC_ENABLE */
#if defined(NX_DISABLE_TCP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
if (compute_checksum)
#endif /* defined(NX_DISABLE_TCP_TX_CHECKSUM ) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
{
/* Set the packet source IP address. */
#ifndef NX_DISABLE_IPV4
if (socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version == NX_IP_VERSION_V4)
{
/* For IPv4 the IP instance has only one global address. */
source_ip = &socket_ptr -> nx_tcp_socket_connect_interface -> nx_interface_ip_address;
/* Set the destination address to the other side of the TCP connection. */
dest_ip = &socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_address.v4;
}
#endif /* !NX_DISABLE_IPV4 */
#ifdef FEATURE_NX_IPV6
if (socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version == NX_IP_VERSION_V6)
{
/* For IPv6, use the source address specified in the socket outgoing interface. */
source_ip = socket_ptr -> nx_tcp_socket_ipv6_addr -> nxd_ipv6_address;
/* Set the destination address to the other side of the TCP connection. */
dest_ip = socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_address.v6;
}
#endif /* FEATURE_NX_IPV6 */
/* Calculate the TCP checksum. */
checksum = _nx_ip_checksum_compute(packet_ptr, NX_PROTOCOL_TCP,
(UINT)packet_ptr -> nx_packet_length, source_ip, dest_ip);
checksum = ~checksum & NX_LOWER_16_MASK;
/* Move the checksum into header. */
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_header_word_4);
tcp_header_ptr -> nx_tcp_header_word_4 = (checksum << NX_SHIFT_BY_16);
NX_CHANGE_ULONG_ENDIAN(tcp_header_ptr -> nx_tcp_header_word_4);
}
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
else
{
packet_ptr -> nx_packet_interface_capability_flag |= NX_INTERFACE_CAPABILITY_TCP_TX_CHECKSUM;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
#ifndef NX_DISABLE_IPV4
/* Send the TCP packet to the IP component. */
if (socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version == NX_IP_VERSION_V4)
{
_nx_ip_packet_send(ip_ptr, packet_ptr, socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_address.v4,
socket_ptr -> nx_tcp_socket_type_of_service, socket_ptr -> nx_tcp_socket_time_to_live, NX_IP_TCP,
socket_ptr -> nx_tcp_socket_fragment_enable,
socket_ptr -> nx_tcp_socket_next_hop_address);
}
#endif /* !NX_DISABLE_IPV4 */
#ifdef FEATURE_NX_IPV6
if (socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_version == NX_IP_VERSION_V6)
{
/* The IPv6 packet interface must be set before sending. Set to the TCP socket outgoing interface. */
packet_ptr -> nx_packet_address.nx_packet_ipv6_address_ptr = socket_ptr -> nx_tcp_socket_ipv6_addr;
_nx_ipv6_packet_send(ip_ptr, packet_ptr, NX_PROTOCOL_TCP, packet_ptr -> nx_packet_length, ip_ptr -> nx_ipv6_hop_limit,
socket_ptr -> nx_tcp_socket_ipv6_addr -> nxd_ipv6_address,
socket_ptr -> nx_tcp_socket_connect_ip.nxd_ip_address.v6);
}
#endif /* FEATURE_NX_IPV6 */
}
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