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Allow use of loopback addresses in IP stack (127.0.0.0/8) #754

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Merged
merged 1 commit into from
Mar 8, 2023
Merged

Allow use of loopback addresses in IP stack (127.0.0.0/8) #754

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6 changes: 4 additions & 2 deletions source/FreeRTOS_ARP.c
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Original file line number Diff line number Diff line change
Expand Up @@ -413,7 +413,8 @@ BaseType_t xCheckRequiresARPResolution( const NetworkBufferDescriptor_t * pxNetw
const IPPacket_t * pxIPPacket = ( ( IPPacket_t * ) pxNetworkBuffer->pucEthernetBuffer );
const IPHeader_t * pxIPHeader = &( pxIPPacket->xIPHeader );

if( ( pxIPHeader->ulSourceIPAddress & xNetworkAddressing.ulNetMask ) == ( *ipLOCAL_IP_ADDRESS_POINTER & xNetworkAddressing.ulNetMask ) )
if( ( ( pxIPHeader->ulSourceIPAddress & xNetworkAddressing.ulNetMask ) == ( *ipLOCAL_IP_ADDRESS_POINTER & xNetworkAddressing.ulNetMask ) ) &&
( ( pxIPHeader->ulDestinationIPAddress & ipLOOPBACK_NETMASK ) != ( ipLOOPBACK_ADDRESS & ipLOOPBACK_NETMASK ) ) )
{
/* If the IP is on the same subnet and we do not have an ARP entry already,
* then we should send out ARP for finding the MAC address. */
Expand Down Expand Up @@ -726,7 +727,8 @@ eARPLookupResult_t eARPGetCacheEntry( uint32_t * pulIPAddress,
* can be done. */
eReturn = eCantSendPacket;
}
else if( *ipLOCAL_IP_ADDRESS_POINTER == *pulIPAddress )
else if( ( *ipLOCAL_IP_ADDRESS_POINTER == *pulIPAddress ) ||
( ( *pulIPAddress & ipLOOPBACK_NETMASK ) == ( ipLOOPBACK_ADDRESS & ipLOOPBACK_NETMASK ) ) )
{
/* The address of this device. May be useful for the loopback device. */
eReturn = eARPCacheHit;
Expand Down
2 changes: 2 additions & 0 deletions source/FreeRTOS_IP.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1446,6 +1446,8 @@ static eFrameProcessingResult_t prvAllowIPPacket( const IPPacket_t * const pxIPP
else if( ( ulDestinationIPAddress != *ipLOCAL_IP_ADDRESS_POINTER ) &&
/* Is it the global broadcast address 255.255.255.255 ? */
( ulDestinationIPAddress != ipBROADCAST_IP_ADDRESS ) &&
/* Is it a loopback address ? */
( ( ulDestinationIPAddress & ipLOOPBACK_NETMASK ) != ( ipLOOPBACK_ADDRESS & ipLOOPBACK_NETMASK ) ) &&
/* Is it a specific broadcast address 192.168.1.255 ? */
( ulDestinationIPAddress != xNetworkAddressing.ulBroadcastAddress ) &&
#if ( ipconfigUSE_LLMNR == 1 )
Expand Down
4 changes: 4 additions & 0 deletions source/include/FreeRTOS_IP_Private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -387,6 +387,10 @@ extern const BaseType_t xBufferAllocFixedSize;
* rather than duplicated in its own variable. */
#define ipLOCAL_MAC_ADDRESS ( xDefaultPartUDPPacketHeader.ucBytes )

/* The loopback address block is defined as part of rfc5735 */
#define ipLOOPBACK_ADDRESS ( FreeRTOS_inet_addr_quick( 127, 0, 0, 0 ) )
#define ipLOOPBACK_NETMASK ( FreeRTOS_inet_addr_quick( 255, 0, 0, 0 ) )

/* ICMP packets are sent using the same function as UDP packets. The port
* number is used to distinguish between the two, as 0 is an invalid UDP port. */
#define ipPACKET_CONTAINS_ICMP_DATA ( 0 )
Expand Down
40 changes: 40 additions & 0 deletions test/unit-test/FreeRTOS_ARP/FreeRTOS_ARP_utest.c
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Original file line number Diff line number Diff line change
Expand Up @@ -945,6 +945,29 @@ void test_xCheckRequiresARPResolution_OnLocalNetwork_InCache( void )
TEST_ASSERT_EQUAL( pdFALSE, xResult );
}

void test_xCheckRequiresARPResolution_OnLocalNetwork_Loopback( void )
{
NetworkBufferDescriptor_t xNetworkBuffer, * pxNetworkBuffer;
uint8_t ucEthernetBuffer[ ipconfigNETWORK_MTU ];
BaseType_t xResult;

pxNetworkBuffer = &xNetworkBuffer;
pxNetworkBuffer->pucEthernetBuffer = ucEthernetBuffer;

IPPacket_t * pxIPPacket = ( ( IPPacket_t * ) pxNetworkBuffer->pucEthernetBuffer );
IPHeader_t * pxIPHeader = &( pxIPPacket->xIPHeader );

*ipLOCAL_IP_ADDRESS_POINTER = ipLOOPBACK_ADDRESS;

/* Make sure there is a match on source IP and loopback address */
pxIPHeader->ulDestinationIPAddress = *ipLOCAL_IP_ADDRESS_POINTER;
pxIPHeader->ulSourceIPAddress = *ipLOCAL_IP_ADDRESS_POINTER & xNetworkAddressing.ulNetMask;

xResult = xCheckRequiresARPResolution( pxNetworkBuffer );

TEST_ASSERT_EQUAL( pdFALSE, xResult );
}


void test_ulARPRemoveCacheEntryByMac_NoMatch( void )
{
Expand Down Expand Up @@ -1322,6 +1345,23 @@ void test_eARPGetCacheEntry_IPMatchesOtherBroadcastAddr( void )
/* =================================================== */
}

void test_eARPGetCacheEntry_IPMatchesLoopbackAddr( void )
{
uint32_t ulIPAddress;
MACAddress_t xMACAddress;
eARPLookupResult_t eResult;
uint32_t ulSavedGatewayAddress;

/* =================================================== */
ulIPAddress = ipLOOPBACK_ADDRESS;
/* Not worried about what these functions do. */
xIsIPv4Multicast_ExpectAndReturn( ulIPAddress, 0UL );
eResult = eARPGetCacheEntry( &ulIPAddress, &xMACAddress );
TEST_ASSERT_EQUAL_MESSAGE( eARPCacheHit, eResult, "Test 3" );
TEST_ASSERT_EQUAL_MEMORY_MESSAGE( &ipLOCAL_MAC_ADDRESS, &xMACAddress, sizeof( xMACAddress ), "Test 3" );
/* =================================================== */
}

void test_eARPGetCacheEntry_LocalIPIsZero( void )
{
uint32_t ulIPAddress;
Expand Down
35 changes: 35 additions & 0 deletions test/unit-test/FreeRTOS_IP/FreeRTOS_IP_utest.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2249,6 +2249,41 @@ void test_prvAllowIPPacket_IncorrectProtocolChecksum( void )
TEST_ASSERT_EQUAL( eReleaseBuffer, eResult );
}

void test_prvAllowIPPacket_LoopbackDest( void )
{
eFrameProcessingResult_t eResult;
IPPacket_t * pxIPPacket;
NetworkBufferDescriptor_t * pxNetworkBuffer, xNetworkBuffer;
UBaseType_t uxHeaderLength = 0;
uint8_t ucEthBuffer[ ipconfigTCP_MSS ];
IPHeader_t * pxIPHeader;

memset( ucEthBuffer, 0, ipconfigTCP_MSS );

pxNetworkBuffer = &xNetworkBuffer;
pxNetworkBuffer->pucEthernetBuffer = ucEthBuffer;
pxIPPacket = ( IPPacket_t * ) pxNetworkBuffer->pucEthernetBuffer;
pxIPHeader = &( pxIPPacket->xIPHeader );

*ipLOCAL_IP_ADDRESS_POINTER = 0xFFFFFFFF;

pxIPHeader->ucVersionHeaderLength = 0x45;

pxIPHeader->ulDestinationIPAddress = ipLOOPBACK_ADDRESS;

memcpy( pxIPPacket->xEthernetHeader.xDestinationAddress.ucBytes, &ipLOCAL_MAC_ADDRESS, sizeof( MACAddress_t ) );

pxIPHeader->ulSourceIPAddress = 0xC0C00101;

usGenerateChecksum_ExpectAndReturn( 0U, ( uint8_t * ) &( pxIPHeader->ucVersionHeaderLength ), ( size_t ) uxHeaderLength, ipCORRECT_CRC );

usGenerateProtocolChecksum_ExpectAndReturn( ( uint8_t * ) ( pxNetworkBuffer->pucEthernetBuffer ), pxNetworkBuffer->xDataLength, pdFALSE, ipCORRECT_CRC );

eResult = prvAllowIPPacket( pxIPPacket, pxNetworkBuffer, uxHeaderLength );

TEST_ASSERT_EQUAL( eProcessBuffer, eResult );
}

void test_prvAllowIPPacket_HappyPath( void )
{
eFrameProcessingResult_t eResult;
Expand Down