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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_ip.h"
#include "nx_packet.h"
#ifndef NX_DISABLE_FRAGMENTATION
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_ip_fragment_packet PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function breaks the supplied packet into fragments and sends */
/* them out through the associated IP driver. This function uses the */
/* already built IP header and driver request structure for each */
/* packet fragment. */
/* */
/* INPUT */
/* */
/* driver_req_ptr Pointer to driver request */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _nx_ip_packet_checksum_compute Compute checksum */
/* _nx_packet_allocate Allocate packet for fragment */
/* _nx_packet_transmit_release Transmit packet release */
/* (ip_link_driver) User supplied link driver */
/* */
/* CALLED BY */
/* */
/* _nx_arp_packet_receive Received ARP packet processing*/
/* _nx_ip_packet_send Send an IP packet */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Yuxin Zhou Initial Version 6.0 */
/* 09-30-2020 Yuxin Zhou Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
VOID _nx_ip_fragment_packet(struct NX_IP_DRIVER_STRUCT *driver_req_ptr)
{
#ifndef NX_DISABLE_IPV4
UINT status;
ULONG checksum;
ULONG temp;
UCHAR *source_ptr;
ULONG remaining_bytes;
ULONG fragment_size;
ULONG copy_size;
ULONG copy_remaining_size;
ULONG fragment_offset = 0;
NX_IP_DRIVER driver_request;
NX_PACKET *source_packet;
NX_PACKET *fragment_packet;
NX_IPV4_HEADER *source_header_ptr;
NX_IPV4_HEADER *fragment_header_ptr;
NX_IP *ip_ptr;
#if defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY)
UINT compute_checksum = 1;
#endif /* defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) */
#ifdef NX_DISABLE_IP_TX_CHECKSUM
compute_checksum = 0;
#endif /* NX_DISABLE_IP_TX_CHECKSUM */
/* Setup the local driver request packet that will be used for each
fragment. There will be a unique packet pointer for each request, but
otherwise all the other fields will remain constant. */
driver_request = *driver_req_ptr;
/* Setup the IP pointer. */
ip_ptr = driver_req_ptr -> nx_ip_driver_ptr;
#ifndef NX_DISABLE_IP_INFO
/* Increment the total number of fragment requests. */
ip_ptr -> nx_ip_total_fragment_requests++;
#endif
/* Pickup the source packet pointer. */
source_packet = driver_req_ptr -> nx_ip_driver_packet;
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, source_packet);
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
/* Compute checksum for upper layer protocol. */
if (source_packet -> nx_packet_interface_capability_flag)
{
_nx_ip_packet_checksum_compute(source_packet);
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
/* Build a pointer to the source IP header. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
source_header_ptr = (NX_IPV4_HEADER *)source_packet -> nx_packet_prepend_ptr;
/* Endian swapping logic. If NX_LITTLE_ENDIAN is specified, these macros will
swap the endian of the IP header. */
NX_CHANGE_ULONG_ENDIAN(source_header_ptr -> nx_ip_header_word_0);
NX_CHANGE_ULONG_ENDIAN(source_header_ptr -> nx_ip_header_word_1);
NX_CHANGE_ULONG_ENDIAN(source_header_ptr -> nx_ip_header_word_2);
NX_CHANGE_ULONG_ENDIAN(source_header_ptr -> nx_ip_header_source_ip);
NX_CHANGE_ULONG_ENDIAN(source_header_ptr -> nx_ip_header_destination_ip);
/* Pickup the length of the packet and the starting pointer. */
remaining_bytes = (source_packet -> nx_packet_length - (ULONG)sizeof(NX_IPV4_HEADER));
source_ptr = source_packet -> nx_packet_prepend_ptr + sizeof(NX_IPV4_HEADER);
/* Derive the fragment size. */
fragment_size = source_packet -> nx_packet_address.nx_packet_interface_ptr -> nx_interface_ip_mtu_size - (ULONG)sizeof(NX_IPV4_HEADER);
fragment_size = (fragment_size / NX_IP_ALIGN_FRAGS) * NX_IP_ALIGN_FRAGS;
/* Loop to break the source packet into fragments and send each out through
the associated driver. */
while (remaining_bytes)
{
/* Allocate a packet from the default packet pool. */
status = _nx_packet_allocate(ip_ptr -> nx_ip_default_packet_pool, &fragment_packet,
NX_IPv4_PACKET, TX_NO_WAIT);
/* Determine if there is a packet available. */
if (status)
{
#ifndef NX_DISABLE_IP_INFO
/* Increment the fragment failure count. */
ip_ptr -> nx_ip_fragment_failures++;
/* Increment the IP send packets dropped count. */
ip_ptr -> nx_ip_send_packets_dropped++;
/* Increment the IP transmit resource error count. */
ip_ptr -> nx_ip_transmit_resource_errors++;
#endif
/* Error, not enough packets to perform the fragmentation... release the
source packet and return. */
_nx_packet_transmit_release(driver_req_ptr -> nx_ip_driver_packet);
return;
}
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, fragment_packet);
/* Set the proper interface. */
/*lint -e{644} suppress variable might not be initialized, since "fragment_packet" was initialized in _nx_packet_allocate. */
fragment_packet -> nx_packet_address.nx_packet_interface_ptr = driver_req_ptr -> nx_ip_driver_packet -> nx_packet_address.nx_packet_interface_ptr;
/* Calculate the size of this fragment. */
if (remaining_bytes > fragment_size)
{
copy_remaining_size = fragment_size;
remaining_bytes -= fragment_size;
}
else
{
copy_remaining_size = remaining_bytes;
remaining_bytes = 0;
}
/* Copy data. */
while (copy_remaining_size)
{
/* We need to copy the remaining bytes into the new packet and then move to the next
packet. */
/*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
if (copy_remaining_size > (ULONG)(source_packet -> nx_packet_append_ptr - source_ptr))
{
copy_size = (ULONG)(source_packet -> nx_packet_append_ptr - source_ptr);
}
else
{
copy_size = copy_remaining_size;
}
status = _nx_packet_data_append(fragment_packet, source_ptr, copy_size, ip_ptr -> nx_ip_default_packet_pool, NX_NO_WAIT);
/* Determine if there is a packet available. */
if (status)
{
#ifndef NX_DISABLE_IP_INFO
/* Increment the fragment failure count. */
ip_ptr -> nx_ip_fragment_failures++;
/* Increment the IP send packets dropped count. */
ip_ptr -> nx_ip_send_packets_dropped++;
/* Increment the IP transmit resource error count. */
ip_ptr -> nx_ip_transmit_resource_errors++;
#endif
/* Error, not enough packets to perform the fragmentation... release the
source packet and return. */
_nx_packet_transmit_release(driver_req_ptr -> nx_ip_driver_packet);
_nx_packet_release(fragment_packet);
return;
}
/* Reduce the remaining size. */
copy_remaining_size -= copy_size;
/*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
if (copy_size == (ULONG)(source_packet -> nx_packet_append_ptr - source_ptr))
{
/* Move to the next physical packet in the source message. */
/* Determine if there is a next packet. */
if (source_packet -> nx_packet_next)
{
/* Move to the next physical packet in the source message. */
source_packet = source_packet -> nx_packet_next;
/* Setup new source pointer. */
source_ptr = source_packet -> nx_packet_prepend_ptr;
}
else if (remaining_bytes)
{
/* Error, no next packet but current packet is exhausted and there are
remaining bytes. */
#ifndef NX_DISABLE_IP_INFO
/* Increment the invalid transmit packet count. */
ip_ptr -> nx_ip_invalid_transmit_packets++;
/* Increment the fragment failures count. */
ip_ptr -> nx_ip_fragment_failures++;
#endif
/* Error, not enough packets to perform the fragmentation... release the
source packet and return. */
_nx_packet_transmit_release(driver_req_ptr -> nx_ip_driver_packet);
_nx_packet_release(fragment_packet);
return;
}
}
else
{
/* Copy finished. */
source_ptr += copy_size;
}
}
/* Setup the fragment packet pointers. */
fragment_packet -> nx_packet_prepend_ptr = fragment_packet -> nx_packet_prepend_ptr - sizeof(NX_IPV4_HEADER);
fragment_packet -> nx_packet_length += (ULONG)sizeof(NX_IPV4_HEADER);
/* Setup the fragment's IP header. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
fragment_header_ptr = (NX_IPV4_HEADER *)fragment_packet -> nx_packet_prepend_ptr;
/* Setup the new IP header. */
fragment_header_ptr -> nx_ip_header_word_0 = (source_header_ptr -> nx_ip_header_word_0 & ~NX_LOWER_16_MASK) |
fragment_packet -> nx_packet_length;
fragment_header_ptr -> nx_ip_header_word_1 = source_header_ptr -> nx_ip_header_word_1 | (fragment_offset / 8);
fragment_header_ptr -> nx_ip_header_word_2 = source_header_ptr -> nx_ip_header_word_2 & ~NX_LOWER_16_MASK;
fragment_header_ptr -> nx_ip_header_source_ip = source_header_ptr -> nx_ip_header_source_ip;
fragment_header_ptr -> nx_ip_header_destination_ip = source_header_ptr -> nx_ip_header_destination_ip;
/* Determine if this is the last fragment. */
if (remaining_bytes)
{
/* Not the last fragment, so set the more fragments bit. */
fragment_header_ptr -> nx_ip_header_word_1 = fragment_header_ptr -> nx_ip_header_word_1 | NX_IP_MORE_FRAGMENT;
}
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
if (fragment_packet -> 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 */
#if defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY)
if (compute_checksum)
#endif /* defined(NX_DISABLE_IP_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) */
{
/* Build the IP checksum for this fragment. */
temp = fragment_header_ptr -> nx_ip_header_word_0;
checksum = (temp >> NX_SHIFT_BY_16) + (temp & NX_LOWER_16_MASK);
temp = fragment_header_ptr -> nx_ip_header_word_1;
checksum += (temp >> NX_SHIFT_BY_16) + (temp & NX_LOWER_16_MASK);
temp = fragment_header_ptr -> nx_ip_header_word_2;
checksum += (temp >> NX_SHIFT_BY_16);
temp = fragment_header_ptr -> nx_ip_header_source_ip;
checksum += (temp >> NX_SHIFT_BY_16) + (temp & NX_LOWER_16_MASK);
temp = fragment_header_ptr -> nx_ip_header_destination_ip;
checksum += (temp >> NX_SHIFT_BY_16) + (temp & NX_LOWER_16_MASK);
/* Add in the carry bits into the checksum. */
checksum = (checksum >> NX_SHIFT_BY_16) + (checksum & NX_LOWER_16_MASK);
/* Do it again in case previous operation generates an overflow. */
checksum = (checksum >> NX_SHIFT_BY_16) + (checksum & NX_LOWER_16_MASK);
/* Now store the checksum in the IP fragment header. */
fragment_header_ptr -> nx_ip_header_word_2 = fragment_header_ptr -> nx_ip_header_word_2 | (NX_LOWER_16_MASK & (~checksum));
}
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
else
{
fragment_packet -> nx_packet_interface_capability_flag |= NX_INTERFACE_CAPABILITY_IPV4_TX_CHECKSUM;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
/* Endian swapping logic. If NX_LITTLE_ENDIAN is specified, these macros will
swap the endian of the IP header. */
NX_CHANGE_ULONG_ENDIAN(fragment_header_ptr -> nx_ip_header_word_0);
NX_CHANGE_ULONG_ENDIAN(fragment_header_ptr -> nx_ip_header_word_1);
NX_CHANGE_ULONG_ENDIAN(fragment_header_ptr -> nx_ip_header_word_2);
NX_CHANGE_ULONG_ENDIAN(fragment_header_ptr -> nx_ip_header_source_ip);
NX_CHANGE_ULONG_ENDIAN(fragment_header_ptr -> nx_ip_header_destination_ip);
#ifndef NX_DISABLE_IP_INFO
/* Increment the IP fragments sent count. */
ip_ptr -> nx_ip_total_fragments_sent++;
/* Increment the IP packet sent count. */
ip_ptr -> nx_ip_total_packets_sent++;
/* Increment the IP bytes sent count. */
ip_ptr -> nx_ip_total_bytes_sent += fragment_packet -> nx_packet_length - (ULONG)sizeof(NX_IPV4_HEADER);
#endif
/* Send the packet to the associated driver for output. */
driver_request.nx_ip_driver_packet = fragment_packet;
/* If trace is enabled, insert this event into the trace buffer. */
NX_TRACE_IN_LINE_INSERT(NX_TRACE_INTERNAL_IO_DRIVER_PACKET_SEND, ip_ptr, fragment_packet, fragment_packet -> nx_packet_length, 0, NX_TRACE_INTERNAL_EVENTS, 0, 0);
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, fragment_packet);
(fragment_packet -> nx_packet_address.nx_packet_interface_ptr -> nx_interface_link_driver_entry)(&driver_request);
/* Increase offset. */
fragment_offset += fragment_size;
}
#ifndef NX_DISABLE_IP_INFO
/* Increment the total number of successful fragment requests. */
ip_ptr -> nx_ip_successful_fragment_requests++;
#endif
/* The original packet has been sent out in fragments... release it! */
_nx_packet_transmit_release(driver_req_ptr -> nx_ip_driver_packet);
#else
NX_PARAMETER_NOT_USED(driver_req_ptr);
#endif /* NX_DISABLE_IPV4 */
}
#endif /* NX_DISABLE_FRAGMENTATION */