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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"
#if !defined(NX_DISABLE_FRAGMENTATION) && !defined(NX_DISABLE_IPV4)
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_ip_fragment_forward_packet PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function breaks the supplied forward packet into fragments and */
/* sends them out. This function uses the already built IP header and */
/* source packet structure for each packet fragment. */
/* */
/* INPUT */
/* */
/* ip_ptr Pointer to IP control block */
/* source_packet Pointer to packet to send */
/* destination_ip Destination IP address */
/* fragment Don't fragment bit */
/* next_hop_address Next Hop address */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _nx_ip_packet_checksum_compute Compute checksum */
/* _nx_packet_allocate Allocate packet for fragment */
/* _nx_packet_data_append Copies the specified data */
/* _nx_packet_release Packet release */
/* _nx_packet_transmit_release Transmit packet release */
/* _nx_ip_driver_packet_send Send the IP packet */
/* */
/* CALLED BY */
/* */
/* _nx_ip_forward_packet_process Process the forward 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_forward_packet(NX_IP *ip_ptr, NX_PACKET *source_packet, ULONG destination_ip, ULONG fragment, ULONG next_hop_address)
{
UINT status;
ULONG checksum;
ULONG temp;
UCHAR *source_ptr;
ULONG remaining_bytes;
ULONG fragment_size;
ULONG copy_size;
ULONG copy_remaining_size;
ULONG more_fragment;
ULONG fragment_offset;
NX_PACKET *fragment_packet;
NX_IPV4_HEADER *source_header_ptr;
NX_IPV4_HEADER *fragment_header_ptr;
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, source_packet);
#ifndef NX_DISABLE_IP_INFO
/* Increment the total number of fragment requests. */
ip_ptr -> nx_ip_total_fragment_requests++;
#endif
#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);
more_fragment = source_header_ptr -> nx_ip_header_word_1 & NX_IP_MORE_FRAGMENT;
fragment_offset = (source_header_ptr -> nx_ip_header_word_1 & NX_IP_OFFSET_MASK) * NX_IP_ALIGN_FRAGS;
/* Clear the fragment bits and offset mask. */
source_header_ptr -> nx_ip_header_word_1 &= 0xFFFF0000;
/* 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(source_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 = source_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))
{
/*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
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(source_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(source_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. */
/*lint -e{539} suppress positive indentation. */
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;
}
else
{
/* Set the more fragments bit. */
fragment_header_ptr -> nx_ip_header_word_1 = fragment_header_ptr -> nx_ip_header_word_1 | 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))
{
#endif /* 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
{
/* Clear checksum. */
fragment_header_ptr -> nx_ip_header_word_2 &= 0xFFFF0000;
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
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, fragment_packet);
/* Call the function to directly forward the packet. */
_nx_ip_driver_packet_send(ip_ptr, fragment_packet, destination_ip, fragment, next_hop_address);
/* 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(source_packet);
}
#endif /* !defined(NX_DISABLE_FRAGMENTATION) && !defined(NX_DISABLE_IPV4) */