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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 Control Message Protocol (ICMP) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SOURCE_CODE
/* Include necessary system files. */
#include "nx_api.h"
#include "nx_packet.h"
#include "nx_ip.h"
#include "nx_icmp.h"
#ifdef NX_IPSEC_ENABLE
#include "nx_ipsec.h"
#endif /* NX_IPSEC_ENABLE */
#ifndef NX_DISABLE_IPV4
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_icmpv4_process_echo_request PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Yuxin Zhou, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This internal function processes incoming echo request message. */
/* It validates the echo request and sends an echo reply back to the */
/* sender. */
/* */
/* INPUT */
/* */
/* ip_ptr Pointer to IP control block */
/* packet_ptr ICMP packet pointer */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _nx_ip_route_find Find a suitable outgoing */
/* interface. */
/* _nx_ip_packet_send Send ICMP packet out */
/* _nx_packet_release Release packet to packet pool */
/* */
/* CALLED BY */
/* */
/* _nx_icmpv4_packet_process Main ICMP packet pocess */
/* */
/* 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_icmpv4_process_echo_request(NX_IP *ip_ptr, NX_PACKET *packet_ptr)
{
NX_ICMPV4_HEADER *header_ptr;
ULONG checksum;
ULONG old_m;
#if defined(NX_DISABLE_ICMPV4_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
ULONG compute_checksum = 1;
#endif /* defined(NX_DISABLE_ICMPV4_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
NX_IPV4_HEADER *ipv4_header;
ULONG next_hop_address = NX_NULL;
#ifdef NX_IPSEC_ENABLE
ULONG data_offset;
VOID *sa = NX_NULL;
NXD_ADDRESS src_addr;
NXD_ADDRESS dest_addr;
UINT ret;
#endif /* NX_IPSEC_ENABLE */
/* Add debug information. */
NX_PACKET_DEBUG(__FILE__, __LINE__, packet_ptr);
/* Point to the ICMP message header. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
header_ptr = (NX_ICMPV4_HEADER *)packet_ptr -> nx_packet_prepend_ptr;
/* Pickup the return IP address. */
/*lint -e{927} -e{826} suppress cast of pointer to pointer, since it is necessary */
ipv4_header = (NX_IPV4_HEADER *)packet_ptr -> nx_packet_ip_header;
#ifndef NX_DISABLE_ICMP_INFO
/* Increment the ICMP pings received count. */
ip_ptr -> nx_ip_pings_received++;
#endif
/* Change the type to Echo Reply and send back the message to the caller. */
header_ptr -> nx_icmpv4_header_type = NX_ICMP_ECHO_REPLY_TYPE;
#ifdef NX_IPSEC_ENABLE
src_addr.nxd_ip_version = NX_IP_VERSION_V4;
src_addr.nxd_ip_address.v4 = packet_ptr -> nx_packet_address.nx_packet_interface_ptr -> nx_interface_ip_address;
dest_addr.nxd_ip_version = NX_IP_VERSION_V4;
dest_addr.nxd_ip_address.v4 = ipv4_header -> nx_ip_header_source_ip;
/* Check if IPsec is enabled. */
if (ip_ptr -> nx_ip_packet_egress_sa_lookup != NX_NULL)
{
/* Check for possible SA match. */
ret = ip_ptr -> nx_ip_packet_egress_sa_lookup(ip_ptr, /* IP ptr */
&src_addr, /* src_addr */
&dest_addr, /* dest_addr */
NX_PROTOCOL_ICMP, /* protocol */
0, /* port, not used. */
0, /* port, not used. */
&data_offset, &sa, (NX_ICMP_ECHO_REPLY_TYPE << 8));
/* Do the IPSec SA rules permit this packet to be sent? */
if (ret == NX_IPSEC_TRAFFIC_PROTECT)
{
/* Yes; make sure the outgoing packet has enough space for IPsec header info. */
if ((ULONG)(packet_ptr -> nx_packet_prepend_ptr - packet_ptr -> nx_packet_data_start) <
(NX_IPv4_PACKET + data_offset))
{
/* Not enough space. Release the packet and return. */
_nx_packet_release(packet_ptr);
return;
}
/* Save the SA to the packet. */
packet_ptr -> nx_packet_ipsec_sa_ptr = sa;
}
else if (ret == NX_IPSEC_TRAFFIC_DROP || ret == NX_IPSEC_TRAFFIC_PENDING_IKEV2)
{
/* No; Drop the packet and return. */
_nx_packet_release(packet_ptr);
return;
}
else
{
/* SA rules indicate to bypass IPSec processing. Zero out the
SA information. */
packet_ptr -> nx_packet_ipsec_sa_ptr = NX_NULL;
}
}
#endif /* NX_IPSEC_ENABLE */
#ifdef NX_DISABLE_ICMPV4_TX_CHECKSUM
compute_checksum = 0;
#endif /* NX_DISABLE_ICMPV4_TX_CHECKSUM */
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
if (packet_ptr -> nx_packet_address.nx_packet_interface_ptr -> nx_interface_capability_flag & NX_INTERFACE_CAPABILITY_ICMPV4_TX_CHECKSUM)
{
compute_checksum = 0;
}
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
#ifdef NX_IPSEC_ENABLE
if ((sa != NX_NULL) && (((NX_IPSEC_SA *)sa) -> nx_ipsec_sa_encryption_method != NX_CRYPTO_NONE))
{
compute_checksum = 1;
}
#endif /* NX_IPSEC_ENABLE */
#if defined(NX_DISABLE_ICMPV4_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE)
if (compute_checksum)
#endif /* defined(NX_DISABLE_ICMPV4_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY) || defined(NX_IPSEC_ENABLE) */
{
/* Update the checksum, according to the RFC1624 page2, Eqn.3.
HC - old checksum in header
HC' - new checksum in header
m - old value of a 16-bit field
m' - new value of a 16-bit field
HC' = ~(C + (-m) + m')
= ~(~HC + ~m + m') */
/* Endian swapping logic. */
NX_CHANGE_USHORT_ENDIAN(header_ptr -> nx_icmpv4_header_checksum);
/* Get the old checksum (HC) in header. */
checksum = header_ptr -> nx_icmpv4_header_checksum;
/* Get the old type(m). */
old_m = (ULONG)(NX_ICMP_ECHO_REQUEST_TYPE << 8);
/* Update the checksum, get the new checksum(HC'). */
/* The m' is value of echo reply type. It is zero so can be ignored. */
checksum = ((~checksum) & 0xFFFF) + ((~old_m) & 0xFFFF);
/* Fold a 4-byte value into a two byte value */
checksum = (checksum >> 16) + (checksum & 0xFFFF);
/* Do it again in case previous operation generates an overflow */
checksum = (checksum >> 16) + (checksum & 0xFFFF);
/* Store the checksum. */
header_ptr -> nx_icmpv4_header_checksum = (~checksum & NX_LOWER_16_MASK);
/* If NX_LITTLE_ENDIAN is defined, the header need to be swapped back
for output (network byte order). */
NX_CHANGE_USHORT_ENDIAN(header_ptr -> nx_icmpv4_header_checksum);
}
#if defined(NX_DISABLE_ICMPV4_TX_CHECKSUM) || defined(NX_ENABLE_INTERFACE_CAPABILITY)
else
{
/* Clear the checksum. */
header_ptr -> nx_icmpv4_header_checksum = 0;
#ifdef NX_ENABLE_INTERFACE_CAPABILITY
packet_ptr -> nx_packet_interface_capability_flag |= NX_INTERFACE_CAPABILITY_ICMPV4_TX_CHECKSUM;
#endif /* NX_ENABLE_INTERFACE_CAPABILITY */
}
#endif
/* Figure out the best interface to send the ICMP packet on. */
_nx_ip_route_find(ip_ptr, ipv4_header -> nx_ip_header_source_ip,
&packet_ptr -> nx_packet_address.nx_packet_interface_ptr,
&next_hop_address);
/* If trace is enabled, insert this event into the trace buffer. */
NX_TRACE_IN_LINE_INSERT(NX_TRACE_INTERNAL_ICMP_RECEIVE, ip_ptr, ipv4_header -> nx_ip_header_source_ip, packet_ptr, 0, NX_TRACE_INTERNAL_EVENTS, 0, 0);
#ifndef NX_DISABLE_ICMP_INFO
/* Increment the ICMP pings responded to count. */
ip_ptr -> nx_ip_pings_responded_to++;
#endif
/* Send the ICMP packet to the IP component. */
/*lint -e{644} suppress variable might not be initialized, since "next_hop_address" was initialized in _nx_ip_route_find. */
_nx_ip_packet_send(ip_ptr, packet_ptr, ipv4_header -> nx_ip_header_source_ip,
NX_IP_NORMAL, NX_IP_TIME_TO_LIVE, NX_IP_ICMP, NX_FRAGMENT_OKAY, next_hop_address);
}
#endif /* !NX_DISABLE_IPV4 */
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