protected AHHeader(short hops, AHHeader head) {
//Set a new number of hops:
Hops = hops;
//Copy the rest:
Ttl = head.Ttl;
Opts = head.Opts;
_src = head._src;
_dest = head._dest;
_data = head._data;
}
public void Send(ICopyable data) {
/*
* Assemble an AHPacket:
*/
if( _header == null ) {
AHHeader ahh = new AHHeader(_hops, _ttl, _source, _dest, _options);
_header = MemBlock.Copy(new CopyList( PType.Protocol.AH, ahh));
_header_length = _header.Length;
}
byte[] ah_packet;
int packet_length;
int packet_offset;
//Try to get the shared BufferAllocator, useful when
//we don't know how big the data is, which in general
//is just as expensive as doing a CopyTo...
BufferAllocator ba = Interlocked.Exchange<BufferAllocator>(ref _buf_alloc, null);
if( ba != null ) {
try {
ah_packet = ba.Buffer;
packet_offset = ba.Offset;
int tmp_off = packet_offset;
tmp_off += _header.CopyTo(ah_packet, packet_offset);
tmp_off += data.CopyTo(ah_packet, tmp_off);
packet_length = tmp_off - packet_offset;
ba.AdvanceBuffer(packet_length);
}
catch(System.Exception x) {
throw new SendException(false, "could not write the packet, is it too big?", x);
}
finally {
//Put the BA back
Interlocked.Exchange<BufferAllocator>(ref _buf_alloc, ba);
}
}
else {
//Oh well, someone else is using the buffer, just go ahead
//and allocate new memory:
packet_offset = 0;
packet_length = _header_length + data.Length;
ah_packet = new byte[ packet_length ];
int off_to_data = _header.CopyTo(ah_packet, 0);
data.CopyTo(ah_packet, off_to_data);
}
MemBlock mb_packet = MemBlock.Reference(ah_packet, packet_offset, packet_length);
/*
* Now we announce this packet, the AHHandler will
* handle routing it for us
*/
_n.HandleData(mb_packet, _from, this);
}
/**
* Here we handle routing AHPackets
*/
public void HandleData(MemBlock data, ISender ret_path, object st) {
AHState state = _state; //Read the state, it can't change after the read
var header = new AHHeader(data);
var payload = data.Slice(header.Length);
Connection next_con;
//Check to see if we can use a Leaf connection:
int dest_idx = state.Leafs.IndexOf(header.Destination);
if( dest_idx >= 0 ) {
next_con = state.Leafs[dest_idx];
}
else {
var alg = state.GetRoutingAlgo(header);
Pair<Connection, bool> result = alg.NextConnection(ret_path as Edge, header);
if( result.Second ) {
//Send a response exactly back to the node that sent to us
var resp_send = new AHSender(_n, ret_path, header.Source,
_n.DefaultTTLFor(header.Source),
AHHeader.Options.Exact);
_n.HandleData( payload, resp_send, this);
}
next_con = result.First;
}
//Send it on:
if( next_con != null ) {
//Now we do the sending:
var new_packet = new CopyList(PType.Protocol.AH,
header.IncrementHops(),
payload);
try {
next_con.Edge.Send(new_packet);
}
catch(EdgeException) {
//Just drop the packet...
}
}
}
public AHRoutingAlgorithm GetRoutingAlgo(AHHeader head) {
int addclass = head.Destination.Class;
if( addclass == AHAddress.ClassValue ) {
ushort opts = head.Opts;
if( opts == AHHeader.Options.Last
|| opts == AHHeader.Options.Greedy ) {
return _greedy;
}
else {
return _annealing;
}
}
else if( addclass == DirectionalAddress.ClassValue ) {
return _directional;
}
else {
throw new Exception(
String.Format("No router for class: {0}", addclass));
}
}
public override Pair<Connection, bool> NextConnection(Edge from, AHHeader h) {
DirectionalAddress dest = (DirectionalAddress)h.Destination;
if( h.Ttl <= h.Hops ) {
//Deliver it to us but stop it here:
return _NULL_TRUE;
}
if ( dest.Bearing == DirectionalAddress.Direction.Left ) {
if( h.Opts == AHHeader.Options.Path ) {
return _LEFT_TRUE;
}
else {
return _LEFT_FALSE;
}
}
else if (dest.Bearing == DirectionalAddress.Direction.Right) {
if( h.Opts == AHHeader.Options.Path ) {
return _RIGHT_TRUE;
}
else {
return _RIGHT_FALSE;
}
}
else {
throw new System.Exception(
System.String.Format("Unrecognized direction: {0}", dest.Bearing));
}
}
public override Pair<Connection, bool> NextConnection(Edge from, AHHeader head) {
Address dest = head.Destination;
int d_idx = _structs.IndexOf(dest);
if( d_idx >= 0 ) {
//We have a direct connection:
Connection next = _structs[d_idx];
if( next != _local_con ) {
return new Pair<Connection,bool>(next, false);
}
else {
return new Pair<Connection, bool>(null, true);
}
}
else {
var ah_dest = (AHAddress)dest;
int left_idx = ~d_idx;
Connection l_c = _structs[left_idx];
int right_idx = left_idx - 1;
Connection r_c = _structs[right_idx];
Connection next_con;
Connection other_con;
if( ah_dest.IsCloserToFirst((AHAddress)l_c.Address, (AHAddress)r_c.Address) ) {
next_con = l_c;
other_con = r_c;
}
else {
next_con = r_c;
other_con = l_c;
}
//See if we need to get it:
/* everyone gets "path" packets,
* if it's exact, only the destination gets it, handled above
* otherwise, only the two nodes on either side of the destination get
* it
*/
bool local = head.Opts == AHHeader.Options.Path ||
((next_con == _local_con || other_con == _local_con)
&& head.Opts != AHHeader.Options.Exact);
Connection to_send;
//Check not to send it back the way it came:
if(from == null) {
/*
* This packet is from us, so just send it to the closest
* node, other than us.
*/
to_send = _local_con != next_con ? next_con : other_con;
}
else if(next_con.Edge == from) {
//Don't send it back the way it came:
to_send = other_con;
}
else {
//Great, the closest has not yet been visited:
to_send = next_con;
}
//Now, make sure not to send it to ourselves:
to_send = to_send == _local_con ? null : to_send;
return new Pair<Connection, bool>(to_send, local);
}
}
public override Pair<Connection, bool> NextConnection(Edge from, AHHeader head) {
Address dest = head.Destination;
int d_idx = _structs.IndexOf(dest);
Connection next_con;
if( d_idx >= 0 ) {
//We have a direct connection:
next_con = _structs[d_idx];
}
else {
//We have to check the right and the left:
var ah_dest = (AHAddress)dest;
int left_idx = ~d_idx;
Connection l_c = _structs[left_idx];
int right_idx = left_idx - 1;
Connection r_c = _structs[right_idx];
if( ah_dest.IsCloserToFirst((AHAddress)l_c.Address, (AHAddress)r_c.Address) ) {
next_con = l_c;
}
else {
next_con = r_c;
}
/*
* Note, DO NOT DO COMPARISONS WITH INDEX VALUES!!!!!
* do the the wrap around, _structs[x] == _structs[y]
* when x = y + k * _structs.Count for all k, so equality
* of Connection is not the same as equality of index
*/
if( head.Hops >= head.Ttl ) {
//Only deliver if we are the closest or last mode:
bool local = next_con == _local_con || head.Opts == AHHeader.Options.Last;
if( local ) {
return _LOCAL;
}
else {
return _NO_ONE;
}
}
}
return next_con == _local_con ? _LOCAL : new Pair<Connection, bool>(next_con, false);
}
/** compute the next step in the route * @param from the Edge the packet came in on * @param head the header to route * @return next connection and bool indicating if local node should get * packet. If there is no next connection, the connection will be null */ public abstract Pair<Connection, bool> NextConnection(Edge from, AHHeader head);
