error_t ipv4CheckDestAddr(NetInterface *interface, Ipv4Addr ipAddr)
{
uint_t i;
//Filter out any invalid addresses
error_t error = ERROR_INVALID_ADDRESS;
//Broadcast address?
if(ipv4IsBroadcastAddr(interface, ipAddr))
{
//Always accept broadcast address
error = NO_ERROR;
}
//Multicast address?
else if(ipv4IsMulticastAddr(ipAddr))
{
//Acquire exclusive access to the IPv4 filter table
osAcquireMutex(&interface->ipv4FilterMutex);
//Loop through the IPv4 filter table
for(i = 0; i < interface->ipv4FilterSize; i++)
{
//Check whether the destination IPv4 address matches
//a relevant multicast address
if(interface->ipv4Filter[i].addr == ipAddr)
{
//The multicast address is acceptable
error = NO_ERROR;
//Stop immediately
break;
}
}
//Release exclusive access to the IPv4 filter table
osReleaseMutex(&interface->ipv4FilterMutex);
}
//Unicast address?
else
{
//The destination address matches the host address?
if(interface->ipv4Config.addrState != IPV4_ADDR_STATE_INVALID &&
interface->ipv4Config.addr == ipAddr)
{
//The destination address is acceptable
error = NO_ERROR;
}
}
//Return status code
return error;
}
error_t ipv4CheckDestAddr(NetInterface *interface, Ipv4Addr ipAddr)
{
//Host IPv4 address?
if(ipAddr == interface->ipv4Config.addr)
return NO_ERROR;
//Broadcast address?
if(ipv4IsBroadcastAddr(interface, ipAddr))
return NO_ERROR;
//Debug message
TRACE_WARNING("Wrong destination IPv4 address!\r\n");
//The destination address is not acceptable
return ERROR_INVALID_ADDRESS;
}
error_t ipv4CheckSourceAddr(NetInterface *interface, Ipv4Addr ipAddr)
{
//Broadcast and multicast addresses must not be used as source
//address (see RFC 1122 3.2.1.3)
if(ipv4IsBroadcastAddr(interface, ipAddr) || ipv4IsMulticastAddr(ipAddr))
{
//Debug message
TRACE_WARNING("Wrong source IPv4 address!\r\n");
//The source address not is acceptable
return ERROR_INVALID_ADDRESS;
}
//The source address is acceptable
return NO_ERROR;
}
error_t icmpSendErrorMessage(NetInterface *interface, uint8_t type,
uint8_t code, uint8_t parameter, const ChunkedBuffer *ipPacket)
{
error_t error;
size_t offset;
size_t length;
Ipv4Header *ipHeader;
ChunkedBuffer *icmpMessage;
IcmpErrorMessage *icmpHeader;
Ipv4PseudoHeader pseudoHeader;
//Retrieve the length of the invoking IPv4 packet
length = chunkedBufferGetLength(ipPacket);
//Check the length of the IPv4 packet
if(length < sizeof(Ipv4Header))
return ERROR_INVALID_LENGTH;
//Point to the header of the invoking packet
ipHeader = chunkedBufferAt(ipPacket, 0);
//Sanity check
if(!ipHeader) return ERROR_FAILURE;
//Never respond to a packet destined to a broadcast or a multicast address
if(ipv4IsBroadcastAddr(interface, ipHeader->destAddr) ||
ipv4IsMulticastAddr(ipHeader->destAddr))
{
//Report an error
return ERROR_INVALID_ADDRESS;
}
//Length of the data that will be returned along with the ICMP header
length = MIN(length, ipHeader->headerLength * 4 + 8);
//Allocate a memory buffer to hold the ICMP message
icmpMessage = ipAllocBuffer(sizeof(IcmpErrorMessage), &offset);
//Failed to allocate memory?
if(!icmpMessage) return ERROR_OUT_OF_MEMORY;
//Point to the ICMP header
icmpHeader = chunkedBufferAt(icmpMessage, offset);
//Format ICMP message
icmpHeader->type = type;
icmpHeader->code = code;
icmpHeader->checksum = 0;
icmpHeader->parameter = parameter;
icmpHeader->unused = 0;
//Copy the IP header and the first 8 bytes of the original datagram data
error = chunkedBufferConcat(icmpMessage, ipPacket, 0, length);
//Any error to report?
if(error)
{
//Clean up side effects
chunkedBufferFree(icmpMessage);
//Exit immediately
return error;
}
//Get the length of the resulting message
length = chunkedBufferGetLength(icmpMessage) - offset;
//Message checksum calculation
icmpHeader->checksum = ipCalcChecksumEx(icmpMessage, offset, length);
//Format IPv4 pseudo header
pseudoHeader.srcAddr = ipHeader->destAddr;
pseudoHeader.destAddr = ipHeader->srcAddr;
pseudoHeader.reserved = 0;
pseudoHeader.protocol = IPV4_PROTOCOL_ICMP;
pseudoHeader.length = htons(length);
//Debug message
TRACE_INFO("Sending ICMP Error message (%" PRIuSIZE " bytes)...\r\n", length);
//Dump message contents for debugging purpose
icmpDumpErrorMessage(icmpHeader);
//Send ICMP Error message
error = ipv4SendDatagram(interface, &pseudoHeader,
icmpMessage, offset, IPV4_DEFAULT_TTL);
//Free previously allocated memory
chunkedBufferFree(icmpMessage);
//Return status code
return error;
}
void arpProcessReply(NetInterface *interface, ArpPacket *arpReply)
{
ArpCacheEntry *entry;
//Debug message
TRACE_INFO("ARP Reply received...\r\n");
//Check sender protocol address
if(arpReply->spa == IPV4_UNSPECIFIED_ADDR)
return;
if(ipv4IsMulticastAddr(arpReply->spa))
return;
if(ipv4IsBroadcastAddr(interface, arpReply->spa))
return;
//Check sender hardware address
if(macCompAddr(&arpReply->sha, &MAC_UNSPECIFIED_ADDR))
return;
if(macCompAddr(&arpReply->sha, &MAC_BROADCAST_ADDR))
return;
//Acquire exclusive access to ARP cache
osMutexAcquire(interface->arpCacheMutex);
//Search the ARP cache for the specified IPv4 address
entry = arpFindEntry(interface, arpReply->spa);
//A matching ARP entry has been found
if(entry)
{
//Check current state
if(entry->state == ARP_STATE_INCOMPLETE)
{
//Record the corresponding MAC address
entry->macAddr = arpReply->sha;
//Send all the packets that are pending for transmission
arpSendQueuedPackets(interface, entry);
//Save current time
entry->timestamp = osGetTickCount();
//The validity of the ARP entry is limited in time
entry->timeout = ARP_REACHABLE_TIME;
//Switch to the REACHABLE state
entry->state = ARP_STATE_REACHABLE;
}
else if(entry->state == ARP_STATE_REACHABLE)
{
//Different link-layer address than cached?
if(!macCompAddr(&arpReply->sha, &entry->macAddr))
{
//Enter STALE state
entry->state = ARP_STATE_STALE;
}
}
else if(entry->state == ARP_STATE_PROBE)
{
//Record IPv4/MAC address pair
entry->ipAddr = arpReply->spa;
entry->macAddr = arpReply->sha;
//Save current time
entry->timestamp = osGetTickCount();
//The validity of the ARP entry is limited in time
entry->timeout = ARP_REACHABLE_TIME;
//Switch to the REACHABLE state
entry->state = ARP_STATE_REACHABLE;
}
}
//Release exclusive access to ARP cache
osMutexRelease(interface->arpCacheMutex);
}
void tcpProcessSegment(NetInterface *interface,
IpPseudoHeader *pseudoHeader, const NetBuffer *buffer, size_t offset)
{
uint_t i;
size_t length;
Socket *socket;
Socket *passiveSocket;
TcpHeader *segment;
//Total number of segments received, including those received in error
MIB2_INC_COUNTER32(mib2Base.tcpGroup.tcpInSegs, 1);
MIB2_INC_COUNTER64(mib2Base.tcpGroup.tcpHCInSegs, 1);
//A TCP implementation must silently discard an incoming
//segment that is addressed to a broadcast or multicast
//address (see RFC 1122 4.2.3.10)
#if (IPV4_SUPPORT == ENABLED)
if(pseudoHeader->length == sizeof(Ipv4PseudoHeader))
{
//Ensure the destination address is not a broadcast address
if(ipv4IsBroadcastAddr(interface, pseudoHeader->ipv4Data.destAddr))
return;
//Ensure the destination address is not a multicast address
if(ipv4IsMulticastAddr(pseudoHeader->ipv4Data.destAddr))
return;
}
else
#endif
#if (IPV6_SUPPORT == ENABLED)
if(pseudoHeader->length == sizeof(Ipv6PseudoHeader))
{
//Ensure the destination address is not a multicast address
if(ipv6IsMulticastAddr(&pseudoHeader->ipv6Data.destAddr))
return;
}
else
#endif
{
//This should never occur...
return;
}
//Retrieve the length of the TCP segment
length = netBufferGetLength(buffer) - offset;
//Point to the TCP header
segment = netBufferAt(buffer, offset);
//Sanity check
if(segment == NULL)
return;
//Ensure the TCP header is valid
if(length < sizeof(TcpHeader))
{
//Debug message
TRACE_WARNING("TCP segment length is invalid!\r\n");
//Total number of segments received in error
MIB2_INC_COUNTER32(mib2Base.tcpGroup.tcpInErrs, 1);
//Exit immediately
return;
}
//Check header length
if(segment->dataOffset < 5 || (segment->dataOffset * 4) > length)
{
//Debug message
TRACE_WARNING("TCP header length is invalid!\r\n");
//Total number of segments received in error
MIB2_INC_COUNTER32(mib2Base.tcpGroup.tcpInErrs, 1);
//Exit immediately
return;
}
//Verify TCP checksum
if(ipCalcUpperLayerChecksumEx(pseudoHeader->data,
pseudoHeader->length, buffer, offset, length) != 0x0000)
{
//Debug message
TRACE_WARNING("Wrong TCP header checksum!\r\n");
//Total number of segments received in error
MIB2_INC_COUNTER32(mib2Base.tcpGroup.tcpInErrs, 1);
//Exit immediately
return;
}
//No matching socket in the LISTEN state for the moment
passiveSocket = NULL;
//Look through opened sockets
for(i = 0; i < SOCKET_MAX_COUNT; i++)
{
//Point to the current socket
socket = socketTable + i;
//TCP socket found?
if(socket->type != SOCKET_TYPE_STREAM)
continue;
//Check whether the socket is bound to a particular interface
if(socket->interface && socket->interface != interface)
continue;
//Check destination port number
if(socket->localPort != ntohs(segment->destPort))
continue;
#if (IPV4_SUPPORT == ENABLED)
//An IPv4 packet was received?
if(pseudoHeader->length == sizeof(Ipv4PseudoHeader))
{
//Destination IP address filtering
if(socket->localIpAddr.length)
{
//An IPv4 address is expected
if(socket->localIpAddr.length != sizeof(Ipv4Addr))
continue;
//Filter out non-matching addresses
if(socket->localIpAddr.ipv4Addr != pseudoHeader->ipv4Data.destAddr)
continue;
}
//Source IP address filtering
if(socket->remoteIpAddr.length)
{
//An IPv4 address is expected
if(socket->remoteIpAddr.length != sizeof(Ipv4Addr))
continue;
//Filter out non-matching addresses
if(socket->remoteIpAddr.ipv4Addr != pseudoHeader->ipv4Data.srcAddr)
continue;
}
}
else
#endif
#if (IPV6_SUPPORT == ENABLED)
//An IPv6 packet was received?
if(pseudoHeader->length == sizeof(Ipv6PseudoHeader))
{
//Destination IP address filtering
if(socket->localIpAddr.length)
{
//An IPv6 address is expected
if(socket->localIpAddr.length != sizeof(Ipv6Addr))
continue;
//Filter out non-matching addresses
if(!ipv6CompAddr(&socket->localIpAddr.ipv6Addr, &pseudoHeader->ipv6Data.destAddr))
continue;
}
//Source IP address filtering
if(socket->remoteIpAddr.length)
{
//An IPv6 address is expected
if(socket->remoteIpAddr.length != sizeof(Ipv6Addr))
continue;
//Filter out non-matching addresses
if(!ipv6CompAddr(&socket->remoteIpAddr.ipv6Addr, &pseudoHeader->ipv6Data.srcAddr))
continue;
}
}
else
#endif
//An invalid packet was received?
{
//This should never occur...
continue;
}
//Keep track of the first matching socket in the LISTEN state
if(socket->state == TCP_STATE_LISTEN && !passiveSocket)
passiveSocket = socket;
//Source port filtering
if(socket->remotePort != ntohs(segment->srcPort))
continue;
//A matching socket has been found
break;
}
//If no matching socket has been found then try to
//use the first matching socket in the LISTEN state
if(i >= SOCKET_MAX_COUNT) socket = passiveSocket;
//Offset to the first data byte
offset += segment->dataOffset * 4;
//Calculate the length of the data
length -= segment->dataOffset * 4;
//Debug message
TRACE_DEBUG("%s: TCP segment received (%" PRIuSIZE " data bytes)...\r\n",
formatSystemTime(osGetSystemTime(), NULL), length);
//Dump TCP header contents for debugging purpose
if(!socket)
tcpDumpHeader(segment, length, 0, 0);
else
tcpDumpHeader(segment, length, socket->irs, socket->iss);
//Convert from network byte order to host byte order
segment->srcPort = ntohs(segment->srcPort);
segment->destPort = ntohs(segment->destPort);
segment->seqNum = ntohl(segment->seqNum);
segment->ackNum = ntohl(segment->ackNum);
segment->window = ntohs(segment->window);
segment->urgentPointer = ntohs(segment->urgentPointer);
//Specified port is unreachable?
if(!socket)
{
//An incoming segment not containing a RST causes
//a reset to be sent in response
if(!(segment->flags & TCP_FLAG_RST))
tcpSendResetSegment(interface, pseudoHeader, segment, length);
//Return immediately
return;
}
//Check current state
switch(socket->state)
{
//Process CLOSED state
case TCP_STATE_CLOSED:
//This is the default state that each connection starts in before
//the process of establishing it begins
tcpStateClosed(interface, pseudoHeader, segment, length);
break;
//Process LISTEN state
case TCP_STATE_LISTEN:
//A device (normally a server) is waiting to receive a synchronize (SYN)
//message from a client. It has not yet sent its own SYN message
tcpStateListen(socket, interface, pseudoHeader, segment, length);
break;
//Process SYN_SENT state
case TCP_STATE_SYN_SENT:
//The device (normally a client) has sent a synchronize (SYN) message and
//is waiting for a matching SYN from the other device (usually a server)
tcpStateSynSent(socket, segment, length);
break;
//Process SYN_RECEIVED state
case TCP_STATE_SYN_RECEIVED:
//The device has both received a SYN from its partner and sent its own SYN.
//It is now waiting for an ACK to its SYN to finish connection setup
tcpStateSynReceived(socket, segment, buffer, offset, length);
break;
//Process ESTABLISHED state
case TCP_STATE_ESTABLISHED:
//Data can be exchanged freely once both devices in the connection enter
//this state. This will continue until the connection is closed
tcpStateEstablished(socket, segment, buffer, offset, length);
break;
//Process CLOSE_WAIT state
case TCP_STATE_CLOSE_WAIT:
//The device has received a close request (FIN) from the other device. It
//must now wait for the application to acknowledge this request and
//generate a matching request
tcpStateCloseWait(socket, segment, length);
break;
//Process LAST_ACK state
case TCP_STATE_LAST_ACK:
//A device that has already received a close request and acknowledged it,
//has sent its own FIN and is waiting for an ACK to this request
tcpStateLastAck(socket, segment, length);
break;
//Process FIN_WAIT_1 state
case TCP_STATE_FIN_WAIT_1:
//A device in this state is waiting for an ACK for a FIN it has sent, or
//is waiting for a connection termination request from the other device
tcpStateFinWait1(socket, segment, buffer, offset, length);
break;
//Process FIN_WAIT_2 state
case TCP_STATE_FIN_WAIT_2:
//A device in this state has received an ACK for its request to terminate the
//connection and is now waiting for a matching FIN from the other device
tcpStateFinWait2(socket, segment, buffer, offset, length);
break;
//Process CLOSING state
case TCP_STATE_CLOSING:
//The device has received a FIN from the other device and sent an ACK for
//it, but not yet received an ACK for its own FIN message
tcpStateClosing(socket, segment, length);
break;
//Process TIME_WAIT state
case TCP_STATE_TIME_WAIT:
//The device has now received a FIN from the other device and acknowledged
//it, and sent its own FIN and received an ACK for it. We are done, except
//for waiting to ensure the ACK is received and prevent potential overlap
//with new connections
tcpStateTimeWait(socket, segment, length);
break;
//Invalid state...
default:
//Back to the CLOSED state
tcpChangeState(socket, TCP_STATE_CLOSED);
//Silently discard incoming packet
break;
}
}
error_t ipv4SendPacket(NetInterface *interface, Ipv4PseudoHeader *pseudoHeader,
uint16_t fragId, uint16_t fragOffset, ChunkedBuffer *buffer, size_t offset, uint8_t timeToLive)
{
error_t error;
size_t length;
Ipv4Addr destIpAddr = 0;
MacAddr destMacAddr;
Ipv4Header *packet;
//Is there enough space for the IPv4 header?
if(offset < sizeof(Ipv4Header))
return ERROR_INVALID_PARAMETER;
//Make room for the header
offset -= sizeof(Ipv4Header);
//Calculate the size of the entire packet, including header and data
length = chunkedBufferGetLength(buffer) - offset;
//Point to the IPv4 header
packet = chunkedBufferAt(buffer, offset);
//Format IPv4 header
packet->version = IPV4_VERSION;
packet->headerLength = 5;
packet->typeOfService = 0;
packet->totalLength = htons(length);
packet->identification = htons(fragId);
packet->fragmentOffset = htons(fragOffset);
packet->timeToLive = timeToLive;
packet->protocol = pseudoHeader->protocol;
packet->headerChecksum = 0;
packet->srcAddr = pseudoHeader->srcAddr;
packet->destAddr = pseudoHeader->destAddr;
//Calculate IP header checksum
packet->headerChecksum = ipCalcChecksumEx(buffer, offset, packet->headerLength * 4);
//Ensure the source address is valid
error = ipv4CheckSourceAddr(interface, pseudoHeader->srcAddr);
//Invalid source address?
if(error) return error;
//Destination address is the unspecified address?
if(pseudoHeader->destAddr == IPV4_UNSPECIFIED_ADDR)
{
//Destination address is not acceptable
error = ERROR_INVALID_ADDRESS;
}
//Destination address is the loopback address?
else if(pseudoHeader->destAddr == IPV4_LOOPBACK_ADDR)
{
//Not yet implemented...
error = ERROR_NOT_IMPLEMENTED;
}
//Destination address is a broadcast address?
else if(ipv4IsBroadcastAddr(interface, pseudoHeader->destAddr))
{
//Destination IPv4 address
destIpAddr = pseudoHeader->destAddr;
//Make use of the broadcast MAC address
destMacAddr = MAC_BROADCAST_ADDR;
//No error to report
error = NO_ERROR;
}
//Destination address is a multicast address?
else if(ipv4IsMulticastAddr(pseudoHeader->destAddr))
{
//Destination IPv4 address
destIpAddr = pseudoHeader->destAddr;
//Map IPv4 multicast address to MAC-layer multicast address
error = ipv4MapMulticastAddrToMac(pseudoHeader->destAddr, &destMacAddr);
}
//Destination host is in the local subnet?
else if(ipv4IsInLocalSubnet(interface, pseudoHeader->destAddr))
{
//Destination IPv4 address
destIpAddr = pseudoHeader->destAddr;
//Resolve host address before sending the packet
error = arpResolve(interface, pseudoHeader->destAddr, &destMacAddr);
}
//Destination host is outside the local subnet?
else
{
//Make sure the default gateway is properly set
if(interface->ipv4Config.defaultGateway != IPV4_UNSPECIFIED_ADDR)
{
//Use the default gateway to forward the packet
destIpAddr = interface->ipv4Config.defaultGateway;
//Perform address resolution
error = arpResolve(interface, interface->ipv4Config.defaultGateway, &destMacAddr);
}
else
{
//There is no route to the outside world...
error = ERROR_NO_ROUTE;
}
}
//Successful address resolution?
if(!error)
{
//Debug message
TRACE_INFO("Sending IPv4 packet (%u bytes)...\r\n", length);
//Dump IP header contents for debugging purpose
ipv4DumpHeader(packet);
//Send Ethernet frame
error = ethSendFrame(interface, &destMacAddr, buffer, offset, ETH_TYPE_IPV4);
}
//Address resolution is in progress?
else if(error == ERROR_IN_PROGRESS)
{
//Debug message
TRACE_INFO("Enqueuing IPv4 packet (%u bytes)...\r\n", length);
//Dump IP header contents for debugging purpose
ipv4DumpHeader(packet);
//Enqueue packets waiting for address resolution
error = arpEnqueuePacket(interface, destIpAddr, buffer, offset);
}
//Address resolution failed?
else
{
//Debug message
TRACE_WARNING("Cannot map IPv4 address to Ethernet address!\r\n");
}
//Return status code
return error;
}