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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 */
/** */
/** Internet Protocol (IP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_packet.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_packet_data_extract_offset PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function copies data from a NetX packet (or packet chain) into */
/* the supplied user buffer. If an empty packet (no data) is */
/* received, zero bytes are copied, and the function returns without */
/* errors. */
/* */
/* Note that this function extracts data from a packet into user */
/* supplied buffer. It does not modify packet internal state */
/* information. The data being extracted is still available in the */
/* original packet for consumption again. */
/* */
/* INPUT */
/* */
/* packet_ptr Pointer to the source packet */
/* offset Offset from start of data */
/* buffer_start Pointer to destination data area */
/* buffer_length Size in bytes */
/* bytes_copied Number of bytes copied */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* None */
/* */
/* 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), and */
/* verified memcpy use cases, */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _nx_packet_data_extract_offset(NX_PACKET *packet_ptr, ULONG offset, VOID *buffer_start, ULONG buffer_length, ULONG *bytes_copied)
{
ULONG remaining_bytes;
UCHAR *source_ptr;
UCHAR *destination_ptr;
ULONG offset_bytes;
#ifndef NX_DISABLE_PACKET_CHAIN
ULONG packet_fragment_length;
#endif /* NX_DISABLE_PACKET_CHAIN */
ULONG bytes_to_copy;
NX_PACKET *working_packet_ptr;
working_packet_ptr = packet_ptr;
/* Check for an invalid offset or packet length. */
if (offset >= working_packet_ptr -> nx_packet_length)
{
/* Note: A zero offset with a packet of zero length is ok. */
if (offset == 0)
{
*bytes_copied = 0;
return(NX_SUCCESS);
}
/* Otherwise, this is an invalid offset or packet length. */
return(NX_PACKET_OFFSET_ERROR);
}
/* Initialize the source pointer to NULL. */
source_ptr = NX_NULL;
/* Traverse packet chain to offset. */
offset_bytes = offset;
#ifndef NX_DISABLE_PACKET_CHAIN
while (working_packet_ptr)
{
/*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
packet_fragment_length = (ULONG)((working_packet_ptr -> nx_packet_append_ptr - working_packet_ptr -> nx_packet_prepend_ptr));
/* Determine if we are at the offset location fragment in the packet chain */
if (packet_fragment_length > offset_bytes)
{
/* Setup loop to copy from this packet. */
source_ptr = working_packet_ptr -> nx_packet_prepend_ptr + offset_bytes;
/* Yes, get out of this loop. */
break;
}
/* Decrement the remaining offset bytes*/
offset_bytes = offset_bytes - packet_fragment_length;
/* Move to next packet. */
working_packet_ptr = working_packet_ptr -> nx_packet_next;
}
#else /* NX_DISABLE_PACKET_CHAIN */
/* Setup loop to copy from this packet. */
source_ptr = working_packet_ptr -> nx_packet_prepend_ptr + offset_bytes;
#endif /* NX_DISABLE_PACKET_CHAIN */
/* Check for a valid source pointer. */
if (source_ptr == NX_NULL)
{
return(NX_PACKET_OFFSET_ERROR);
}
/* Setup the destination pointer. */
destination_ptr = buffer_start;
bytes_to_copy = (packet_ptr -> nx_packet_length - offset);
/* Pickup the amount of bytes to copy. */
if (bytes_to_copy < buffer_length)
{
*bytes_copied = bytes_to_copy; /* the amount of bytes returned to the caller */
remaining_bytes = bytes_to_copy; /* for use in the copy loop */
}
else
{
*bytes_copied = buffer_length;
remaining_bytes = buffer_length;
}
#ifndef NX_DISABLE_PACKET_CHAIN
/* Loop to copy bytes from packet(s). */
while (working_packet_ptr && remaining_bytes)
{
#endif /* NX_DISABLE_PACKET_CHAIN */
/* Calculate bytes to copy. */
/*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
bytes_to_copy = (ULONG)(working_packet_ptr -> nx_packet_append_ptr - source_ptr);
if (remaining_bytes < bytes_to_copy)
{
bytes_to_copy = remaining_bytes;
}
/* Copy data from this packet. */
memcpy(destination_ptr, source_ptr, bytes_to_copy); /* Use case of memcpy is verified. */
/* Update the pointers. */
destination_ptr += bytes_to_copy;
remaining_bytes -= bytes_to_copy;
#ifndef NX_DISABLE_PACKET_CHAIN
/* Move to next packet. */
working_packet_ptr = working_packet_ptr -> nx_packet_next;
/* Check for a next packet. */
if (working_packet_ptr)
{
/* Setup new source pointer. */
source_ptr = working_packet_ptr -> nx_packet_prepend_ptr;
}
}
#endif /* NX_DISABLE_PACKET_CHAIN */
/* If trace is enabled, insert this event into the trace buffer. */
NX_TRACE_IN_LINE_INSERT(NX_TRACE_PACKET_DATA_EXTRACT_OFFSET, packet_ptr, buffer_length, *bytes_copied, 0, NX_TRACE_PACKET_EVENTS, 0, 0);
/* Return successful completion. */
return(NX_SUCCESS);
}
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