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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 */
/** */
/** Internet Protocol (IP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_ip.h"
#include "nx_igmp.h"
#ifdef NX_IPSEC_ENABLE
#include "nx_ipsec.h"
#endif /* NX_IPSEC_ENABLE */
#ifndef NX_DISABLE_IPV4
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_ip_header_add PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function prepends an IP header. */
/* */
/* INPUT */
/* */
/* ip_ptr Pointer to IP control block */
/* packet_ptr Pointer to packet to send */
/* source_ip Source IP address */
/* destination_ip Destination IP address */
/* type_of_service Type of service for packet */
/* time_to_live Time to live value for packet */
/* protocol Protocol being encapsulated */
/* fragment Don't fragment bit */
/* */
/* OUTPUT */
/* */
/* NX_SUCCESS Added the header successfully */
/* NX_UNDERFLOW Invalid packet header */
/* */
/* CALLS */
/* */
/* _nx_ip_checksum_compute Compute IP checksum */
/* _nx_packet_transmit_release Release transmit packet */
/* */
/* CALLED BY */
/* */
/* NetX Source Code */
/* */
/**************************************************************************/
UINT _nx_ip_header_add(NX_IP *ip_ptr, NX_PACKET *packet_ptr, ULONG source_ip, ULONG destination_ip,
ULONG type_of_service, ULONG time_to_live, ULONG protocol, ULONG fragment)
{
ULONG router_alert = 0;
NX_IPV4_HEADER *ip_header_ptr;
ULONG checksum;
#if defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
UINT compute_checksum = 1;
#endif /* defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
ULONG val;
#ifdef NX_ENABLE_IP_ID_RANDOMIZATION
NX_PARAMETER_NOT_USED(ip_ptr);
#endif /* NX_ENABLE_IP_ID_RANDOMIZATION */
#ifndef NX_DISABLE_IGMPV2
/* Check IGMPv2 protocol. */
if ((protocol == NX_IP_IGMP) && (ip_ptr -> nx_ip_igmp_router_version == NX_IGMP_HOST_VERSION_2))
{
router_alert = 4;
}
#endif
/* Prepend the IP header to the packet. First, make room for the IP header. */
packet_ptr -> nx_packet_prepend_ptr = (packet_ptr -> nx_packet_prepend_ptr - sizeof(NX_IPV4_HEADER)) - router_alert;
/* Increase the packet length. */
packet_ptr -> nx_packet_length = packet_ptr -> nx_packet_length + (ULONG)sizeof(NX_IPV4_HEADER) + router_alert;
/* Assert prepend pointer is no less than data start pointer. */
/*lint -e{946} suppress pointer subtraction, since it is necessary. */
NX_ASSERT(packet_ptr -> nx_packet_prepend_ptr >= packet_ptr -> nx_packet_data_start);
/* Setup the IP header pointer. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
ip_header_ptr = (NX_IPV4_HEADER *)packet_ptr -> nx_packet_prepend_ptr;
packet_ptr -> nx_packet_ip_header = packet_ptr -> nx_packet_prepend_ptr;
packet_ptr -> nx_packet_ip_header_length = (UCHAR)(packet_ptr -> nx_packet_ip_header_length +
sizeof(NX_IPV4_HEADER) + router_alert);
/* Determine if this is an identical copy for TCP retransmission.
RFC1122, Section3.2.1.5, Page32-33. RFC1122, Section4.2.2.15, Page90-91. */
if (packet_ptr -> nx_packet_identical_copy == NX_TRUE)
{
/* Yes, this an identical copy for TCP retransmission.
The IP header has been added, return. */
return(NX_SUCCESS);
}
/* Build the IP header. */
#ifndef NX_DISABLE_IGMPV2
if (router_alert)
{
/* Build the first 32-bit word of the IP header. */
ip_header_ptr -> nx_ip_header_word_0 = (ULONG)((NX_IP_VERSION_V4 << 28) |
(NX_IP_HEADER_LENGTH_ENCODE_6 << 24) |
type_of_service |
(0xFFFF & packet_ptr -> nx_packet_length));
}
else
#endif
{
/* Build the first 32-bit word of the IP header. */
ip_header_ptr -> nx_ip_header_word_0 = (NX_IP_VERSION | type_of_service | (0xFFFF & packet_ptr -> nx_packet_length));
}
/* Build the second 32-bit word of the IP header. */
#ifdef NX_ENABLE_IP_ID_RANDOMIZATION
ip_header_ptr -> nx_ip_header_word_1 = (((ULONG)NX_RAND()) << NX_SHIFT_BY_16) | fragment;
#else
ip_header_ptr -> nx_ip_header_word_1 = (ip_ptr -> nx_ip_packet_id++ << NX_SHIFT_BY_16) | fragment;
#endif /* NX_ENABLE_IP_ID_RANDOMIZATION */
/* Build the third 32-bit word of the IP header. */
ip_header_ptr -> nx_ip_header_word_2 = ((time_to_live << NX_IP_TIME_TO_LIVE_SHIFT) | protocol);
/* Place the source IP address in the IP header. */
ip_header_ptr -> nx_ip_header_source_ip = source_ip;
/* Place the destination IP address in the IP header. */
ip_header_ptr -> nx_ip_header_destination_ip = destination_ip;
#ifndef NX_DISABLE_IGMPV2
if (router_alert)
{
/* Append Router Alert Option. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
*((ULONG *)(packet_ptr -> nx_packet_prepend_ptr + sizeof(NX_IPV4_HEADER))) = (NX_IP_OPTION_COPY_FLAG |
NX_IP_OPTION_CLASS |
NX_IP_OPTION_ROUTER_ALERT_NUMBER |
NX_IP_OPTION_ROUTER_ALERT_LENGTH |
NX_IP_OPTION_ROUTER_ALERT_VALUE);
}
#endif
/* Endian swapping logic. If NX_LITTLE_ENDIAN is specified, these macros will
swap the endian of the IP header. */
NX_CHANGE_ULONG_ENDIAN(ip_header_ptr -> nx_ip_header_word_0);
NX_CHANGE_ULONG_ENDIAN(ip_header_ptr -> nx_ip_header_word_1);
NX_CHANGE_ULONG_ENDIAN(ip_header_ptr -> nx_ip_header_word_2);
NX_CHANGE_ULONG_ENDIAN(ip_header_ptr -> nx_ip_header_source_ip);
NX_CHANGE_ULONG_ENDIAN(ip_header_ptr -> nx_ip_header_destination_ip);
#ifndef NX_DISABLE_IGMPV2
if (router_alert)
{
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
NX_CHANGE_ULONG_ENDIAN(*((ULONG *)(packet_ptr -> nx_packet_prepend_ptr + sizeof(NX_IPV4_HEADER))));
}
#endif
#ifdef NX_DISABLE_IP_TX_CHECKSUM
compute_checksum = 0;
#endif /* NX_DISABLE_IP_TX_CHECKSUM */
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
if (packet_ptr -> nx_packet_address.nx_packet_interface_ptr -> nx_interface_capability_flag & NX_INTERFACE_CAPABILITY_IPV4_TX_CHECKSUM)
{
compute_checksum = 0;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
#ifdef NX_IPSEC_ENABLE
if (packet_ptr -> nx_packet_ipsec_sa_ptr != NX_NULL)
{
if ((((NX_IPSEC_SA *)(packet_ptr -> nx_packet_ipsec_sa_ptr)) -> nx_ipsec_sa_mode == NX_IPSEC_TUNNEL_MODE) &&
(((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_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
if (compute_checksum)
#endif /* defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
{
checksum = _nx_ip_checksum_compute(packet_ptr, NX_IP_VERSION_V4,
/* Length is the size of IP header, including options */
(UINT)(20 + router_alert),
/* IPv4 header checksum does not use src/dest addresses */
NULL, NULL);
val = (ULONG)(~checksum);
val = val & NX_LOWER_16_MASK;
/* Convert to network byte order. */
NX_CHANGE_ULONG_ENDIAN(val);
/* Now store the checksum in the IP header. */
ip_header_ptr -> nx_ip_header_word_2 = ip_header_ptr -> nx_ip_header_word_2 | val;
}
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
else
{
packet_ptr -> nx_packet_interface_capability_flag |= NX_INTERFACE_CAPABILITY_IPV4_TX_CHECKSUM;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
/* Return... */
return(NX_SUCCESS);
}
#endif /* NX_DISABLE_IPV4 */
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