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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 */
/** */
/** Packet Pool Management (Packet) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_packet.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_packet_data_adjust PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function adjusts the packet data to fill the specified header. */
/* */
/* INPUT */
/* */
/* packet_ptr Pointer to the source packet */
/* header_size The size of header */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_packet_allocate Allocate data packet */
/* _nx_packet_data_append Packet data append service */
/* _nx_packet_release Release data packet */
/* */
/* CALLED BY */
/* */
/* _nx_ip_forward_packet_process Forward IP packet */
/* */
/**************************************************************************/
UINT _nx_packet_data_adjust(NX_PACKET *packet_ptr, ULONG header_size)
{
ULONG available_size;
ULONG shift_size;
#ifndef NX_DISABLE_PACKET_CHAIN
UINT status;
ULONG append_size;
UCHAR *data_start;
NX_PACKET *work_ptr;
#endif /* !NX_DISABLE_PACKET_CHAIN */
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, packet_ptr);
/* The header must be filled in one packet. */
if (((ALIGN_TYPE)packet_ptr -> nx_packet_data_end - (ALIGN_TYPE)packet_ptr -> nx_packet_data_start) < header_size)
{
return(NX_UNDERFLOW);
}
/* 1. Check if there is enough space to add header. */
if (((ALIGN_TYPE)packet_ptr -> nx_packet_prepend_ptr - (ALIGN_TYPE)packet_ptr -> nx_packet_data_start) >= header_size)
{
/* Yes. Just return success. */
return(NX_SUCCESS);
}
/* Compute the total avilable size in this packet. */
available_size = (ULONG)(((ALIGN_TYPE)packet_ptr -> nx_packet_prepend_ptr - (ALIGN_TYPE)packet_ptr -> nx_packet_data_start) +
((ALIGN_TYPE)packet_ptr -> nx_packet_data_end - (ALIGN_TYPE)packet_ptr -> nx_packet_append_ptr));
/* 2. Would the header fit into the available space? */
if (available_size >= header_size)
{
/* Yes, adjust the data. */
/* Calculate the shift data size. */
shift_size = (ULONG)((ALIGN_TYPE)packet_ptr -> nx_packet_append_ptr - (ALIGN_TYPE)packet_ptr -> nx_packet_prepend_ptr);
/* Move the data, */
memmove(packet_ptr -> nx_packet_data_start + header_size, packet_ptr -> nx_packet_prepend_ptr, shift_size); /* Use case of memmove is verified. */
/* Update the prepend and append pointer. */
packet_ptr -> nx_packet_prepend_ptr = packet_ptr -> nx_packet_data_start + header_size;
packet_ptr -> nx_packet_append_ptr = packet_ptr -> nx_packet_prepend_ptr + shift_size;
}
else
{
#ifndef NX_DISABLE_PACKET_CHAIN
/* 3. Current packet does not have enough space to fill the header.
Allocate a new packet to fill the overflowing data and chain the packet. */
/* Odd value of header_size is not supported now.
* In _nx_ip_checksum_compute(), nx_packet_append_ptr must not be odd value. */
if (header_size & 1)
{
return(NX_NOT_SUPPORTED);
}
/* Calculate the append data size. */
append_size = header_size - available_size;
/* Set the append data pointer. */
data_start = packet_ptr -> nx_packet_append_ptr - append_size;
/* Allocate a packet. */
status = _nx_packet_allocate(packet_ptr -> nx_packet_pool_owner, &work_ptr, 0, NX_NO_WAIT);
/* Check status. */
if (status)
{
return(status);
}
/* Firstly, append the overflowing data to the new packet.. */
memcpy(work_ptr -> nx_packet_prepend_ptr, data_start, append_size); /* Use case of memcpy is verified. lgtm[cpp/banned-api-usage-required-any] */
work_ptr -> nx_packet_append_ptr = (UCHAR *)((ALIGN_TYPE)work_ptr -> nx_packet_prepend_ptr + append_size);
/* Secondly, calculate the shift data size. */
shift_size = (ULONG)(((ALIGN_TYPE)packet_ptr -> nx_packet_append_ptr - (ALIGN_TYPE)packet_ptr -> nx_packet_prepend_ptr) - append_size);
/* Move the data. */
memmove(packet_ptr -> nx_packet_data_start + header_size, packet_ptr -> nx_packet_prepend_ptr, shift_size); /* Use case of memmove is verified. */
/* Update the prepend and append pointer. */
packet_ptr -> nx_packet_prepend_ptr = packet_ptr -> nx_packet_data_start + header_size;
packet_ptr -> nx_packet_append_ptr = packet_ptr -> nx_packet_prepend_ptr + shift_size;
/* At this point, all the necessary packets have been allocated.
We need to link this new packet to the next of the supplied packet. */
work_ptr -> nx_packet_next = packet_ptr -> nx_packet_next;
packet_ptr -> nx_packet_next = work_ptr;
/* Update the last packet pointer. */
if (packet_ptr -> nx_packet_last == NX_NULL)
{
packet_ptr -> nx_packet_last = work_ptr;
}
#else /* NX_DISABLE_PACKET_CHAIN */
/* Return error code. */
return(NX_UNDERFLOW);
#endif /* !NX_DISABLE_PACKET_CHAIN */
}
/* Return successful completion. */
return(NX_SUCCESS);
}
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