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Adds support for receiving IPv4 and IPv6 multicast groups
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Adds parsing of IGMP and MLD queries.
Sends IGMPv2 and MLDv1 reports on a schedule that is updated based on received IGMP/MLD queries.
Sends unsolicited IGMP and MLD reports on network-up events and on add-membership socket option.
Adds 2 function pointers to the network interface struct that handle adding and removing  multicast MAC addresses.
Adds pxSocket->u.xUDP.xMulticastTTL that can be used for both IPv4 and IPv6
Adds pxSocket->u.xUDP.xMulticastAddress that can be used for both IPv4 and IPv6
Adds socket option defines to add/drop membership as well as change the transmit TTL of multicasts.
Makes all 3 multicast socket options (add/drop/ttl) work with both IPv4 and IPv6
Adds a ucMaximumHops field to NetworkBufferDescriptor_t and assigns it to the proper TTL/HopLimit value based on what packet is being sent.
Adds a NetworkInterface_t * to the socket struct to keep track of which network interface(s) should receive multicasts.
Adds exceptions so that we don't send multicast reports for 224.0.0.1, ff02::1, as well as anything with IPv6 multicast scope of 0 or 1
Adds defines for MLD packets like the Multicast Listener Query and Report
Generates an MLD report for the solicited-node multicast addresses corresponding to all unicast IPv6 addresses
Sends IGMPv2 Leave Group messages whenever the last socket subscribed to a group drops that membership.

Adds ipconfigPERIODIC_MULTICAST_REPORT_INTERVAL for debug purposes when there is no IGMP/MLD querier (+3 squashed commit)

Improves the SAME70 driver to handle adding/removing multicast MAC addresses
Adds a Multicast ToDo list to help keep me on track.
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Emil Popov committed Nov 21, 2023
1 parent c263e33 commit de1c4c0
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Showing 23 changed files with 2,136 additions and 73 deletions.
5 changes: 5 additions & 0 deletions source/FreeRTOS_DNS_Networking.c
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Expand Up @@ -84,6 +84,11 @@
* going to be '0' i.e. success. Thus, return value is discarded */
( void ) FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_SNDTIMEO, &( uxWriteTimeOut_ticks ), sizeof( TickType_t ) );
( void ) FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_RCVTIMEO, &( uxReadTimeOut_ticks ), sizeof( TickType_t ) );
#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
/* Since this socket may be used for LLMNR or mDNS, set the multicast TTL to 1. */
uint8_t ucMulticastTTL = 1;
( void ) FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_IP_MULTICAST_TTL, &( ucMulticastTTL ), sizeof( ucMulticastTTL ) );
#endif
}

return xSocket;
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30 changes: 30 additions & 0 deletions source/FreeRTOS_DNS_Parser.c
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Expand Up @@ -936,6 +936,26 @@
}

xUDPPacket_IPv6->xUDPHeader.usLength = FreeRTOS_htons( ( uint16_t ) lNetLength + ipSIZE_OF_UDP_HEADER );

if( xUDPPacket_IPv6->xUDPHeader.usDestinationPort == FreeRTOS_ntohs( ipMDNS_PORT ) )
{
/* RFC6762, section 11 */
xUDPPacket_IPv6->xIPHeader.ucHopLimit = 255U;
}
else if( xUDPPacket_IPv6->xUDPHeader.usDestinationPort == FreeRTOS_ntohs( ipLLMNR_PORT ) )
{
/* LLMNR: RFC4795 section 2.5 recommends UDP requests and responses use TTL of 255 */

/* Theoretically, LLMNR replies can go "off-link" and create a DDoS scenario. That should be preventable
* by settings our rely's TTL/HopLimit to 1. Please note that in certain situations ( I think unicast
* responses), Wireshark flags some LLMNR packets that have TTL of 1 as too low. */
xUDPPacket_IPv6->xIPHeader.ucHopLimit = 1U;
}
else
{
xUDPPacket_IPv6->xIPHeader.ucHopLimit = ipconfigUDP_TIME_TO_LIVE;
}

vFlip_16( pxUDPHeader->usSourcePort, pxUDPHeader->usDestinationPort );
uxDataLength = ( size_t ) lNetLength + ipSIZE_OF_IPv6_HEADER + ipSIZE_OF_UDP_HEADER + ipSIZE_OF_ETH_HEADER;
}
Expand All @@ -951,8 +971,18 @@
/* HT:endian: should not be translated, copying from packet to packet */
if( pxIPHeader->ulDestinationIPAddress == ipMDNS_IP_ADDRESS )
{
/* RFC6762, section 11 */
pxIPHeader->ucTimeToLive = ipMDNS_TIME_TO_LIVE;
}
else if( pxUDPHeader->usDestinationPort == FreeRTOS_ntohs( ipLLMNR_PORT ) )
{
/* LLMNR: RFC4795 section 2.5 recommends UDP requests and responses use TTL of 255 */

/* Theoretically, LLMNR replies can go "off-link" and create a DDoS scenario. That should be preventable
* by settings our rely's TTL/HopLimit to 1. Please note that in certain situations ( I think unicast
* responses), Wireshark flags some LLMNR packets that have TTL of 1 as too low. */
pxIPHeader->ucTimeToLive = 1;
}
else
{
pxIPHeader->ulDestinationIPAddress = pxIPHeader->ulSourceIPAddress;
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98 changes: 98 additions & 0 deletions source/FreeRTOS_IP.c
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Expand Up @@ -59,6 +59,9 @@
#include "FreeRTOS_DNS.h"
#include "FreeRTOS_Routing.h"
#include "FreeRTOS_ND.h"
#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
#include "FreeRTOS_IGMP.h"
#endif

/** @brief Time delay between repeated attempts to initialise the network hardware. */
#ifndef ipINITIALISATION_RETRY_DELAY
Expand Down Expand Up @@ -467,6 +470,20 @@ static void prvProcessIPEventsAndTimers( void )
/* xQueueReceive() returned because of a normal time-out. */
break;

#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
case eSocketOptAddMembership:
case eSocketOptDropMembership:
{
MulticastAction_t * pxMCA = ( MulticastAction_t * ) xReceivedEvent.pvData;
vModifyMulticastMembership( pxMCA, xReceivedEvent.eEventType );
break;
}

case eMulticastTimerEvent:
vIPMulticast_HandleTimerEvent();
break;
#endif /* ( ipconfigSUPPORT_IP_MULTICAST != 0) */

default:
/* Should not get here. */
break;
Expand Down Expand Up @@ -526,6 +543,11 @@ static void prvIPTask_Initialise( void )
}
#endif /* ( ( ipconfigUSE_DNS_CACHE != 0 ) && ( ipconfigUSE_DNS != 0 ) ) */

/* Init the list that will hold scheduled IGMP reports. */
#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
( void ) vIPMulticast_Init();
#endif

/* Initialisation is complete and events can now be processed. */
xIPTaskInitialised = pdTRUE;
}
Expand Down Expand Up @@ -631,8 +653,76 @@ TaskHandle_t FreeRTOS_GetIPTaskHandle( void )
*/
void vIPNetworkUpCalls( struct xNetworkEndPoint * pxEndPoint )
{
#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
MCastReportData_t * pxMRD;
IPv6_Type_t xAddressType;
MACAddress_t xMACAddress;
#endif /* ( ipconfigSUPPORT_IP_MULTICAST != 0 ) */

pxEndPoint->bits.bEndPointUp = pdTRUE_UNSIGNED;

#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
if( pxEndPoint->bits.bIPv6 == pdTRUE_UNSIGNED )
{
/* Now that the network is up, pxEndPoint->ipv6_settings should hold the actual address of this
* end-point. For unicast addresses, generate the solicited-node multicast address that corresponds
* to the address and generate an MLD report for it.
* ToDo: Figure out what the proper place is to remove multicast addresses that are no longer valid. For
* example when a DHCPv6 lease expires. */
xAddressType = xIPv6_GetIPType( &( pxEndPoint->ipv6_settings.xIPAddress ) );

if( ( xAddressType == eIPv6_LinkLocal ) || ( xAddressType == eIPv6_SiteLocal ) || ( xAddressType == eIPv6_Global ) )
{
if( NULL != ( pxMRD = ( MCastReportData_t * ) pvPortMalloc( sizeof( MCastReportData_t ) ) ) )
{
listSET_LIST_ITEM_OWNER( &( pxMRD->xListItem ), ( void * ) pxMRD );
pxMRD->pxInterface = pxEndPoint->pxNetworkInterface;
pxMRD->xMCastGroupAddress.xIs_IPv6 = pdTRUE_UNSIGNED;

/* Generate the solicited-node multicast address in the form of
* ff02::1:ffnn:nnnn, where nn:nnnn are the last 3 bytes of the IPv6 address. */
pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 0 ] = 0xFFU;
pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 1 ] = 0x02U;
( void ) memset( &pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 2 ], 0x00, 9 );
pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 11 ] = 0x01U;
pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 12 ] = 0xFFU;
( void ) memcpy( &pxMRD->xMCastGroupAddress.xIPAddress.xIP_IPv6.ucBytes[ 13 ], &pxEndPoint->ipv6_settings.xIPAddress.ucBytes[ 13 ], 3 );

if( pdTRUE != xAddMulticastReportToList( pxMRD ) )
{
vPortFree( pxMRD );
pxMRD = NULL;
}
else
{
/* The report was consumed, therefore it was added to the list. Tell the network
* driver to begin receiving the associated MAC address */
if( pxEndPoint->pxNetworkInterface && ( pxEndPoint->pxNetworkInterface->pfAddMulticastMAC != NULL ) )
{
xMACAddress.ucBytes[ 0 ] = 0x33;
xMACAddress.ucBytes[ 1 ] = 0x33;
xMACAddress.ucBytes[ 2 ] = 0xFF;
xMACAddress.ucBytes[ 3 ] = pxEndPoint->ipv6_settings.xIPAddress.ucBytes[ 13 ];
xMACAddress.ucBytes[ 4 ] = pxEndPoint->ipv6_settings.xIPAddress.ucBytes[ 14 ];
xMACAddress.ucBytes[ 5 ] = pxEndPoint->ipv6_settings.xIPAddress.ucBytes[ 15 ];
pxEndPoint->pxNetworkInterface->pfAddMulticastMAC( xMACAddress.ucBytes );
}
}
}
}
} /* if( pxEndPoint->bits.bIPv6 == pdTRUE_UNSIGNED ) */

/* Reschedule all multicast reports associated with this end-point.
* /* Note: countdown is in increments of ipIGMP_TIMER_PERIOD_MS. It's a good idea to spread out all reports a little.
* 200 to 500ms ( xMaxCountdown of 2 - 5 ) should be a good happy medium. If the network we just connected to has a IGMP/MLD querier,
* they will soon ask us for reports anyways, so sending these unsolicited reports is not required. It simply enhances the user
* experience by shortening the time it takes before we begin receiving the multicasts that we care for. */
/* _EP_: vRescheduleAllMulticastReports() is NOT declared in header files because I don't want to expose it to the user */
extern void vRescheduleAllMulticastReports( NetworkInterface_t * pxInterface,
BaseType_t xMaxCountdown );
vRescheduleAllMulticastReports( pxEndPoint->pxNetworkInterface, 5 );
#endif /* ( ipconfigSUPPORT_IP_MULTICAST != 0 ) */

#if ( ipconfigUSE_NETWORK_EVENT_HOOK == 1 )
#if ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 )
{
Expand Down Expand Up @@ -1310,6 +1400,7 @@ void FreeRTOS_SetEndPointConfiguration( const uint32_t * pulIPAddress,
pxNetworkBuffer->pucEthernetBuffer[ ipSOCKET_OPTIONS_OFFSET ] = FREERTOS_SO_UDPCKSUM_OUT;
pxNetworkBuffer->xIPAddress.ulIP_IPv4 = ulIPAddress;
pxNetworkBuffer->usPort = ipPACKET_CONTAINS_ICMP_DATA;
pxNetworkBuffer->ucMaximumHops = ipconfigICMP_TIME_TO_LIVE;
/* xDataLength is the size of the total packet, including the Ethernet header. */
pxNetworkBuffer->xDataLength = uxTotalLength;

Expand Down Expand Up @@ -1976,6 +2067,13 @@ static eFrameProcessingResult_t prvProcessIPPacket( const IPPacket_t * pxIPPacke
break;
#endif /* ( ipconfigUSE_IPv6 != 0 ) */

#if ( ipconfigSUPPORT_IP_MULTICAST != 0 )
case ipPROTOCOL_IGMP:
/* The IP packet contained an IGMP frame. */
eReturn = eProcessIGMPPacket( pxNetworkBuffer );
break;
#endif /* ( ipconfigSUPPORT_IP_MULTICAST != 0 ) */

case ipPROTOCOL_UDP:
/* The IP packet contained a UDP frame. */

Expand Down
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