error_t mldSendListenerDone(NetInterface *interface, Ipv6Addr *ipAddr)
{
error_t error;
size_t offset;
MldMessage *message;
ChunkedBuffer *buffer;
Ipv6PseudoHeader pseudoHeader;
//Make sure the specified address is a valid multicast address
if(!ipv6IsMulticastAddr(ipAddr))
return ERROR_INVALID_ADDRESS;
//The link-scope all-nodes address (FF02::1) is handled as a special
//case. The host never sends a report for that address
if(ipv6CompAddr(ipAddr, &IPV6_LINK_LOCAL_ALL_NODES_ADDR))
return ERROR_INVALID_ADDRESS;
//Allocate a memory buffer to hold a MLD message
buffer = ipAllocBuffer(sizeof(MldMessage), &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the beginning of the MLD message
message = chunkedBufferAt(buffer, offset);
//Format the Multicast Listener Done message
message->type = ICMPV6_TYPE_MULTICAST_LISTENER_DONE_V1;
message->code = 0;
message->checksum = 0;
message->maxRespDelay = 0;
message->reserved = 0;
message->multicastAddr = *ipAddr;
//Format IPv6 pseudo header
pseudoHeader.srcAddr = interface->ipv6Config.linkLocalAddr;
pseudoHeader.destAddr = IPV6_LINK_LOCAL_ALL_ROUTERS_ADDR;
pseudoHeader.length = HTONS(sizeof(MldMessage));
pseudoHeader.reserved = 0;
pseudoHeader.nextHeader = IPV6_ICMPV6_HEADER;
//Message checksum calculation
message->checksum = ipCalcUpperLayerChecksumEx(&pseudoHeader,
sizeof(Ipv6PseudoHeader), buffer, offset, sizeof(MldMessage));
//Debug message
TRACE_INFO("Sending MLD message (%" PRIuSIZE " bytes)...\r\n", sizeof(MldMessage));
//Dump message contents for debugging purpose
mldDumpMessage(message);
//The Multicast Listener Done message is sent to the all-routers multicast address
error = ipv6SendDatagram(interface, &pseudoHeader, buffer, offset, MLD_HOP_LIMIT);
//Free previously allocated memory
chunkedBufferFree(buffer);
//Return status code
return error;
}
void ndpProcessNeighborAdv(NetInterface *interface, Ipv6PseudoHeader *pseudoHeader,
const ChunkedBuffer *buffer, size_t offset, uint8_t hopLimit)
{
size_t length;
NdpNeighborAdvMessage *message;
NdpLinkLayerAddrOption *option;
NdpCacheEntry *entry;
//Retrieve the length of the message
length = chunkedBufferGetLength(buffer) - offset;
//Check the length of the Neighbor Advertisement message
if(length < sizeof(NdpNeighborAdvMessage))
return;
//Point to the beginning of the message
message = chunkedBufferAt(buffer, offset);
//Sanity check
if(!message) return;
//Debug message
TRACE_INFO("Neighbor Advertisement message received (%" PRIuSIZE " bytes)...\r\n", length);
//Dump message contents for debugging purpose
ndpDumpNeighborAdvMessage(message);
//The IPv6 Hop Limit field must have a value of 255 to ensure
//that the packet has not been forwarded by a router
if(hopLimit != NDP_HOP_LIMIT)
return;
//ICMPv6 Code must be 0
if(message->code)
return;
//Check whether the target address is tentative or matches
//a unicast address assigned to the interface
if(ipv6CompAddr(&message->targetAddr, &interface->ipv6Config.linkLocalAddr) &&
interface->ipv6Config.linkLocalAddrState != IPV6_ADDR_STATE_INVALID)
{
//Debug message
TRACE_WARNING("The address %s is a duplicate!\r\n",
ipv6AddrToString(&interface->ipv6Config.linkLocalAddr, NULL));
//The address is a duplicate and should not be used
interface->ipv6Config.linkLocalAddrDup = TRUE;
//Exit immediately
return;
}
else if(ipv6CompAddr(&message->targetAddr, &interface->ipv6Config.globalAddr) &&
interface->ipv6Config.globalAddrState != IPV6_ADDR_STATE_INVALID)
{
//Debug message
TRACE_WARNING("The address %s is a duplicate!\r\n",
ipv6AddrToString(&interface->ipv6Config.globalAddr, NULL));
//The address is a duplicate and should not be used
interface->ipv6Config.globalAddrDup = TRUE;
//Exit immediately
return;
}
//The target address must not be a multicast address
if(ipv6IsMulticastAddr(&message->targetAddr))
{
//Debug message
TRACE_WARNING("Target address must not be a multicast address!\r\n");
//Exit immediately
return;
}
//If the destination address is a multicast address
//then the Solicited flag must be zero
if(ipv6IsMulticastAddr(&pseudoHeader->destAddr) && message->s)
{
//Debug message
TRACE_WARNING("Solicited flag must be zero!\r\n");
//Exit immediately
return;
}
//Calculate the length of the Options field
length -= sizeof(NdpNeighborSolMessage);
//Search for the Target Link-Layer Address option
option = ndpGetOption(message->options, length, NDP_OPT_TARGET_LINK_LAYER_ADDR);
//Source Link-Layer Address option found?
if(option && option->length == 1)
{
//Debug message
TRACE_DEBUG(" Target Link-Layer Address = %s\r\n",
macAddrToString(&option->linkLayerAddr, NULL));
//Acquire exclusive access to Neighbor cache
osAcquireMutex(&interface->ndpCacheMutex);
//Search the Neighbor cache for the specified target address
entry = ndpFindEntry(interface, &message->targetAddr);
//If no entry exists, the advertisement should be silently discarded
if(entry)
{
//INCOMPLETE state?
if(entry->state == NDP_STATE_INCOMPLETE)
{
//Record link-layer address
entry->macAddr = option->linkLayerAddr;
//Send all the packets that are pending for transmission
ndpSendQueuedPackets(interface, entry);
//Save current time
entry->timestamp = osGetSystemTime();
//Solicited flag is set?
if(message->s)
{
//Computing the random ReachableTime value
entry->timeout = NDP_REACHABLE_TIME;
//Switch to the REACHABLE state
entry->state = NDP_STATE_REACHABLE;
}
//Solicited flag is cleared?
else
{
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
}
//REACHABLE, STALE, DELAY or PROBE state?
else
{
//Solicited flag is set and Override flag is cleared?
if(message->s && !message->o)
{
//Same link-layer address than cached?
if(macCompAddr(&entry->macAddr, &option->linkLayerAddr))
{
//Save current time
entry->timestamp = osGetSystemTime();
//Computing the random ReachableTime value
entry->timeout = NDP_REACHABLE_TIME;
//Switch to the REACHABLE state
entry->state = NDP_STATE_REACHABLE;
}
//Different link-layer address than cached?
else
{
//REACHABLE state?
if(entry->state == NDP_STATE_REACHABLE)
{
//Save current time
entry->timestamp = osGetSystemTime();
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
}
}
//Both Solicited and Override flags are set?
else if(message->s && message->o)
{
//Record link-layer address (if different)
entry->macAddr = option->linkLayerAddr;
//Save current time
entry->timestamp = osGetSystemTime();
//Computing the random ReachableTime value
entry->timeout = NDP_REACHABLE_TIME;
//Switch to the REACHABLE state
entry->state = NDP_STATE_REACHABLE;
}
//Solicited flag is cleared and Override flag is set?
else if(!message->s && message->o)
{
//Different link-layer address than cached?
if(!macCompAddr(&entry->macAddr, &option->linkLayerAddr))
{
//Record link-layer address
entry->macAddr = option->linkLayerAddr;
//Save current time
entry->timestamp = osGetSystemTime();
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
}
}
}
}
//Source Link-Layer Address option not found?
else
{
//Update content of IsRouter flag
}
//Release exclusive access to Neighbor cache
osReleaseMutex(&interface->ndpCacheMutex);
}
void ndpProcessNeighborSol(NetInterface *interface, Ipv6PseudoHeader *pseudoHeader,
const ChunkedBuffer *buffer, size_t offset, uint8_t hopLimit)
{
size_t length;
NdpNeighborSolMessage *message;
NdpLinkLayerAddrOption *option;
NdpCacheEntry *entry;
//Retrieve the length of the message
length = chunkedBufferGetLength(buffer) - offset;
//Check the length of the Neighbor Solicitation message
if(length < sizeof(NdpNeighborSolMessage))
return;
//Point to the beginning of the message
message = chunkedBufferAt(buffer, offset);
//Sanity check
if(!message) return;
//Debug message
TRACE_INFO("Neighbor Solicitation message received (%" PRIuSIZE " bytes)...\r\n", length);
//Dump message contents for debugging purpose
ndpDumpNeighborSolMessage(message);
//The IPv6 Hop Limit field must have a value of 255 to ensure
//that the packet has not been forwarded by a router
if(hopLimit != NDP_HOP_LIMIT)
return;
//ICMPv6 Code must be 0
if(message->code)
return;
//The target address must a valid unicast address assigned to the interface
//or a tentative address on which DAD is being performed
if(ipv6CompAddr(&message->targetAddr, &interface->ipv6Config.linkLocalAddr))
{
//Check whether the target address is tentative
if(interface->ipv6Config.linkLocalAddrState == IPV6_ADDR_STATE_TENTATIVE)
{
//If the source address of the Neighbor Solicitation is the unspecified
//address, the solicitation is from a node performing Duplicate Address
//Detection
if(ipv6CompAddr(&pseudoHeader->srcAddr, &IPV6_UNSPECIFIED_ADDR))
{
//Debug message
TRACE_WARNING("The tentative address %s is a duplicate!\r\n",
ipv6AddrToString(&interface->ipv6Config.linkLocalAddr, NULL));
//The tentative address is a duplicate and should not be used
interface->ipv6Config.linkLocalAddrDup = TRUE;
}
//In all cases, a node must not respond to a Neighbor Solicitation
//for a tentative address
return;
}
}
else if(ipv6CompAddr(&message->targetAddr, &interface->ipv6Config.globalAddr))
{
//Check whether the target address is tentative
if(interface->ipv6Config.globalAddrState == IPV6_ADDR_STATE_TENTATIVE)
{
//If the source address of the Neighbor Solicitation is the unspecified
//address, the solicitation is from a node performing Duplicate Address
//Detection
if(ipv6CompAddr(&pseudoHeader->srcAddr, &IPV6_UNSPECIFIED_ADDR))
{
//Debug message
TRACE_WARNING("The tentative address %s is a duplicate!\r\n",
ipv6AddrToString(&interface->ipv6Config.globalAddr, NULL));
//The tentative address is a duplicate and should not be used
interface->ipv6Config.globalAddrDup = TRUE;
}
//In all cases, a node must not respond to a Neighbor Solicitation
//for a tentative address
return;
}
}
else
{
//Debug message
TRACE_WARNING("Wrong target address!\r\n");
//Exit immediately
return;
}
//If the IP source address is the unspecified address, the IP
//destination address must be a solicited-node multicast address
if(ipv6CompAddr(&pseudoHeader->srcAddr, &IPV6_UNSPECIFIED_ADDR) &&
!ipv6IsSolicitedNodeAddr(&pseudoHeader->destAddr))
{
//Debug message
TRACE_WARNING("Destination address must be a solicited-node address!\r\n");
//Exit immediately
return;
}
//Calculate the length of the Options field
length -= sizeof(NdpNeighborSolMessage);
//Search for the Source Link-Layer Address option
option = ndpGetOption(message->options, length, NDP_OPT_SOURCE_LINK_LAYER_ADDR);
//Source Link-Layer Address option found?
if(option && option->length == 1)
{
//Debug message
TRACE_DEBUG(" Source Link-Layer Address = %s\r\n",
macAddrToString(&option->linkLayerAddr, NULL));
//If the Source Address is not the unspecified address, then the Neighbor
//cache should be updated for the IP source address of the solicitation
if(ipv6CompAddr(&pseudoHeader->srcAddr, &IPV6_UNSPECIFIED_ADDR))
return;
//Acquire exclusive access to Neighbor cache
osAcquireMutex(&interface->ndpCacheMutex);
//Search the Neighbor cache for the source address of the solicitation
entry = ndpFindEntry(interface, &pseudoHeader->srcAddr);
//No matching entry has been found?
if(!entry)
{
//Create an entry
entry = ndpCreateEntry(interface);
//Neighbor cache entry successfully created?
if(entry)
{
//Record the IPv6 and the corresponding MAC address
entry->ipAddr = pseudoHeader->srcAddr;
entry->macAddr = option->linkLayerAddr;
//Save current time
entry->timestamp = osGetSystemTime();
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
}
else
{
//INCOMPLETE state?
if(entry->state == NDP_STATE_INCOMPLETE)
{
//Record link-layer address
entry->macAddr = option->linkLayerAddr;
//Send all the packets that are pending for transmission
ndpSendQueuedPackets(interface, entry);
//Save current time
entry->timestamp = osGetSystemTime();
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
//REACHABLE, STALE, DELAY or PROBE state?
else
{
//Different link-layer address than cached?
if(!macCompAddr(&entry->macAddr, &option->linkLayerAddr))
{
//Update link-layer address
entry->macAddr = option->linkLayerAddr;
//Save current time
entry->timestamp = osGetSystemTime();
//Enter the STALE state
entry->state = NDP_STATE_STALE;
}
}
}
//Release exclusive access to Neighbor cache
osReleaseMutex(&interface->ndpCacheMutex);
}
//Source Link-Layer Address option not found?
else
{
//This option must be included in multicast solicitations
if(ipv6IsMulticastAddr(&pseudoHeader->destAddr))
{
//Debug message
TRACE_WARNING("The Source Link-Layer Address must be included!\r\n");
//Exit immediately
return;
}
}
//After any updates to the Neighbor cache, the node sends a Neighbor
//Advertisement response as described in RFC 4861 7.2.4
ndpSendNeighborAdv(interface, &message->targetAddr, &pseudoHeader->srcAddr);
}
error_t icmpv6SendErrorMessage(NetInterface *interface, uint8_t type,
uint8_t code, uint32_t parameter, const ChunkedBuffer *ipPacket)
{
error_t error;
size_t offset;
size_t length;
Ipv6Header *ipHeader;
ChunkedBuffer *icmpMessage;
Icmpv6ErrorMessage *icmpHeader;
Ipv6PseudoHeader pseudoHeader;
//Retrieve the length of the invoking IPv6 packet
length = chunkedBufferGetLength(ipPacket);
//Check the length of the IPv6 packet
if(length < sizeof(Ipv6Header))
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 an IPv6 multicast address
if(ipv6IsMulticastAddr(&ipHeader->destAddr))
return ERROR_INVALID_ADDRESS;
//Return as much of invoking IPv6 packet as possible without
//the ICMPv6 packet exceeding the minimum IPv6 MTU
length = MIN(length, IPV6_DEFAULT_MTU -
sizeof(Ipv6Header) - sizeof(Icmpv6ErrorMessage));
//Allocate a memory buffer to hold the ICMPv6 message
icmpMessage = ipAllocBuffer(sizeof(Icmpv6ErrorMessage), &offset);
//Failed to allocate memory?
if(!icmpMessage) return ERROR_OUT_OF_MEMORY;
//Point to the ICMPv6 header
icmpHeader = chunkedBufferAt(icmpMessage, offset);
//Format ICMPv6 Error message
icmpHeader->type = type;
icmpHeader->code = code;
icmpHeader->checksum = 0;
icmpHeader->parameter = htonl(parameter);
//Copy incoming IPv6 packet contents
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;
//Format IPv6 pseudo header
pseudoHeader.srcAddr = ipHeader->destAddr;
pseudoHeader.destAddr = ipHeader->srcAddr;
pseudoHeader.length = htonl(length);
pseudoHeader.reserved = 0;
pseudoHeader.nextHeader = IPV6_ICMPV6_HEADER;
//Message checksum calculation
icmpHeader->checksum = ipCalcUpperLayerChecksumEx(&pseudoHeader,
sizeof(Ipv6PseudoHeader), icmpMessage, offset, length);
//Debug message
TRACE_INFO("Sending ICMPv6 Error message (%" PRIuSIZE " bytes)...\r\n", length);
//Dump message contents for debugging purpose
icmpv6DumpErrorMessage(icmpHeader);
//Send ICMPv6 Error message
error = ipv6SendDatagram(interface, &pseudoHeader,
icmpMessage, offset, IPV6_DEFAULT_HOP_LIMIT);
//Free previously allocated memory
chunkedBufferFree(icmpMessage);
//Return status code
return error;
}
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;
}
}