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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 version 6 (IPv6) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "tx_api.h"
#include "nx_api.h"
#include "nx_ip.h"
#include "nx_ipv6.h"
#include "nx_packet.h"
#ifdef NX_ENABLE_IPV6_PATH_MTU_DISCOVERY
#include "nx_icmpv6.h"
#endif
#if defined(FEATURE_NX_IPV6) && !defined(NX_DISABLE_FRAGMENTATION)
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_ipv6_fragment_process 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 */
/* mtu Maximum transfer unit */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* */
/* CALLS */
/* */
/* _nx_ip_packet_checksum_compute Compute checksum */
/* _nx_packet_allocate Allocate packet */
/* _nx_ipv6_packet_copy Copy packet */
/* _nx_packet_release Release packet */
/* */
/* CALLED BY */
/* */
/* _nx_icmpv6_send_queued_packets */
/* _nx_ipv6_packet_send */
/* */
/* NOTE */
/* */
/* None */
/* */
/* 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_ipv6_fragment_process(struct NX_IP_DRIVER_STRUCT *driver_req_ptr, UINT mtu)
{
NX_PACKET *first_fragment, *source_packet, *previous_packet;
UCHAR *fragmentable_ptr, *last_header_location;
UINT packet_length, unfragmentable_size;
ULONG packet_id;
NX_IP_DRIVER driver_request;
NX_IP *ip_ptr;
UCHAR next_header;
UCHAR hdr_ext_len;
UINT fragment_offset = 0;
INT error = 0;
NX_IPV6_HEADER_FRAGMENT_OPTION *fragment_option;
INT last_fragment = 0;
NX_IPV6_HEADER *ipv6_header;
ULONG word_1;
ULONG val;
NX_PACKET_POOL *pool_ptr;
first_fragment = NX_NULL;
/* 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
/* Source_packet points a packet (or a chain of packets) that already has IP header
constructed. The prepend pointer should point to the IPv6 header. */
packet_id = ip_ptr -> nx_ip_packet_id++;
/* Byte swap packet_id */
NX_CHANGE_ULONG_ENDIAN(packet_id);
/* Pickup the source packet pointer. */
source_packet = driver_req_ptr -> nx_ip_driver_packet;
source_packet -> nx_packet_last = source_packet;
source_packet -> nx_packet_ip_header = source_packet -> nx_packet_prepend_ptr;
pool_ptr = source_packet -> nx_packet_pool_owner;
/* 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 */
/* Find out the unfragmentable part. */
fragmentable_ptr = source_packet -> nx_packet_prepend_ptr + sizeof(NX_IPV6_HEADER);
last_header_location = (source_packet -> nx_packet_prepend_ptr + 6);
next_header = *last_header_location;
#ifdef NX_ENABLE_IPV6_PATH_MTU_DISCOVERY
/* RFC 1981 Section 4 requires that we include a fragment header if we received a
packet from a host with an MTU less than the minimum required path MTU, regardless
if we decide to fragment the packet (which we aren't). */
if (mtu < NX_MINIMUM_IPV6_PATH_MTU)
{
/* So reset the mtu to the minimum packet size. */
mtu = NX_MINIMUM_IPV6_PATH_MTU;
}
#endif
/* Fragment Option header appears after Hop-by-hop and routing headers. So we need
to skip these headers if they are present. */
while ((next_header == NX_PROTOCOL_NEXT_HEADER_HOP_BY_HOP) ||
(next_header == NX_PROTOCOL_NEXT_HEADER_ROUTING))
{
/* Move to the next header */
hdr_ext_len = *(fragmentable_ptr + 1);
last_header_location = fragmentable_ptr;
next_header = *fragmentable_ptr;
/*lint -e{923} suppress cast between pointer and UINT. */
fragmentable_ptr = NX_UCHAR_POINTER_ADD(fragmentable_ptr, ((hdr_ext_len + 1) << 3));
}
/* If hdr_ext_len == 0, there are no optional headers in the unfragmentable region. */
*last_header_location = NX_PROTOCOL_NEXT_HEADER_FRAGMENT;
/* Change the very last "next_header" to
compute the unfragmentable size which includes MAC header, IPv6 header,
and any unfragmentable header, but not the fragment header option. */
/*lint -e{923} suppress cast between pointer and UINT. */
unfragmentable_size = (UINT)((ALIGN_TYPE)fragmentable_ptr - (ALIGN_TYPE)source_packet -> nx_packet_prepend_ptr);
/* Compute the fragmentable size. */
packet_length = (UINT)(source_packet -> nx_packet_length - unfragmentable_size);
/* Add the size of the fragment option header.
This number is going to be used for finding the starting position of
the fragmentable part. */
/* unfragmentable_size += sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);*/
/* Now fragmentable_ptr points to the begining of fragmentable part of 'remaining_pkt' */
/* Also packet_prepend_ptr points to the data (fragmentable) area. */
/* The fragmentable pointer starts from the first packet.*/
while (packet_length)
{
NX_PACKET *new_packet;
UINT fragment_size;
UINT remaining_bytes;
UINT nx_packet_size;
/*
Determine the fragment size. Take the MTU size, minus the unfragmentable
portion, and round down to multiple of 8-bytes, then add the unfragmentable
portion back. This is the size of each fragment, excluding the last fragment.
*/
fragment_size = (mtu - unfragmentable_size) & 0xFFF8;
fragment_size -= (ULONG)sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);
if (fragment_size >= packet_length)
{
fragment_size = packet_length;
last_fragment = 1;
}
/* Compute the remaining packet length */
packet_length -= fragment_size;
/* Figure out the number of bytes (fragmentable part + unfragmentable part)
of this frame. */
remaining_bytes = fragment_size + unfragmentable_size + (UINT)sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION) + NX_PHYSICAL_HEADER;
/* find the size of each nx packet. */
nx_packet_size = (UINT)((pool_ptr -> nx_packet_pool_payload_size) & 0xFFFC);
if (nx_packet_size > (mtu + NX_PHYSICAL_HEADER))
{
nx_packet_size = (mtu + NX_PHYSICAL_HEADER);
}
/* Make sure we have enough packets for this fragment. */
do
{
/* Allocate a packet from the default packet pool. */
if (_nx_packet_allocate(pool_ptr, &new_packet,
0, TX_NO_WAIT))
{
error = 1;
break;
}
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, new_packet);
/*lint -e{644} suppress variable might not be initialized, since "new_packet" was initialized in _nx_packet_allocate. */
new_packet -> nx_packet_ip_version = NX_IP_VERSION_V6;
if (first_fragment == NX_NULL)
{
first_fragment = new_packet;
first_fragment -> nx_packet_last = new_packet;
/* first_fragment -> nx_packet_length = fragment_size + unfragmentable_size. */
/* May need to configure additional header information. */
}
else
{
first_fragment -> nx_packet_last -> nx_packet_next = new_packet;
first_fragment -> nx_packet_last = new_packet;
}
/* Establish the "usable" size of the packet.
The actual copy routine uses this information to figure out how many
bytes to transer to the fragmented packets.*/
/* The true packet size is set in the first packet. */
if (nx_packet_size > remaining_bytes)
{
/* This is going to be the last packet we need. */
new_packet -> nx_packet_length = remaining_bytes;
remaining_bytes = 0;
}
else
{
new_packet -> nx_packet_length = nx_packet_size;
remaining_bytes -= nx_packet_size;
}
} while (remaining_bytes);
if (error)
{
break;
}
/* We have all the packets ready. Need to copy data. */
/* First step: copy the unfragmentable part. */
/* Save the state from last iteration. */
previous_packet = source_packet -> nx_packet_last;
source_packet -> nx_packet_last = source_packet;
source_packet -> nx_packet_prepend_ptr = source_packet -> nx_packet_ip_header;
first_fragment -> nx_packet_last = first_fragment;
first_fragment -> nx_packet_prepend_ptr += NX_PHYSICAL_HEADER;
first_fragment -> nx_packet_append_ptr += NX_PHYSICAL_HEADER;
/* For the first packet, the prepend pointer is already at the begining of the IP header. */
if (_nx_ipv6_packet_copy(source_packet, first_fragment, unfragmentable_size))
{
break;
}
/* Fill in the fragment header area. Be careful here: we assume the unfragmentable part does not
span over multiple packets. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
fragment_option = (NX_IPV6_HEADER_FRAGMENT_OPTION *)first_fragment -> nx_packet_last -> nx_packet_append_ptr;
first_fragment -> nx_packet_append_ptr += sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);
first_fragment -> nx_packet_length += (ULONG)sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);
fragment_option -> nx_ipv6_header_fragment_option_reserved = 0;
fragment_option -> nx_ipv6_header_fragment_option_next_header = next_header;
if (!last_fragment)
{
fragment_option -> nx_ipv6_header_fragment_option_offset_flag = (USHORT)(fragment_offset + 1);
}
else
{
fragment_option -> nx_ipv6_header_fragment_option_offset_flag = (USHORT)fragment_offset;
}
/* Convert to network byte order. */
NX_CHANGE_USHORT_ENDIAN(fragment_option -> nx_ipv6_header_fragment_option_offset_flag);
fragment_option -> nx_ipv6_header_fragment_option_packet_id = packet_id;
/* Restore the nx_packet_last and the prepend pointer within the last packet. */
source_packet -> nx_packet_last = previous_packet;
source_packet -> nx_packet_last -> nx_packet_prepend_ptr = fragmentable_ptr;
/* Copy the rest of the frame. */
if (_nx_ipv6_packet_copy(source_packet, first_fragment, fragment_size))
{
break;
}
/*
Set up the IP frame length. first_fragment -> nx_packet_prepend_ptr points to the
beginning of the IPv6 header.
*/
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
ipv6_header = (NX_IPV6_HEADER *)first_fragment -> nx_packet_prepend_ptr;
/* Pick up the 2nd word in the IP header. */
val = ipv6_header -> nx_ip_header_word_1;
/* Convert to host byte order. */
NX_CHANGE_ULONG_ENDIAN(val);
val = val & 0x0000FFFF;
word_1 = (ULONG)(((fragment_size + unfragmentable_size - sizeof(NX_IPV6_HEADER)) + sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION)) << 16);
word_1 = val | word_1;
/* Convert to network byte order. */
NX_CHANGE_ULONG_ENDIAN(word_1);
ipv6_header -> nx_ip_header_word_1 = word_1;
fragmentable_ptr = source_packet -> nx_packet_last -> nx_packet_prepend_ptr;
fragment_offset += fragment_size;
/* This fragment is ready to be transmitted. */
/* Send the packet to the associated driver for output. */
first_fragment -> nx_packet_length = unfragmentable_size + fragment_size;
first_fragment -> nx_packet_length += (ULONG)sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);
driver_request.nx_ip_driver_packet = first_fragment;
#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 += first_fragment -> nx_packet_length - (ULONG)sizeof(NX_IPV6_HEADER_FRAGMENT_OPTION);
#endif /* !NX_DISABLE_IP_INFO */
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, source_packet);
(source_packet -> nx_packet_address.nx_packet_ipv6_address_ptr -> nxd_ipv6_address_attached -> nx_interface_link_driver_entry)(&driver_request);
first_fragment = NX_NULL;
}
/* Release the original packet. */
_nx_packet_transmit_release(source_packet);
/* In case the fragmentation process fails above, frist_fragment
still contains partial data. Free these fragments before
exiting this function. */
if (first_fragment)
{
_nx_packet_release(first_fragment);
}
return;
}
#endif /* FEATURE_NX_IPV6 && NX_DISABLE_FRAGMENTATION*/
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