TileFluidNode.java

public List<BlockPos> getNeighborPipeBlocks(BlockPos pos, World world) {
	List<BlockPos> result = Lists.newArrayList();
	for (int i = 0; i < EnumFacing.VALUES.length; i++) {
		BlockPos p1 = pos.offset(EnumFacing.VALUES[i]);
		if (world.getBlockState(p1).getBlock() == BlockReference.fluidPipe)
				result.add(p1);
	}
	return result;
}

public Optional<BlockPos> findOutput(BlockPos pos, World world) {
	// NOTE: If you ever add teserects, you'll need to track BlockPos-World pairs.
	LinkedList<BlockPos> queue = Lists.newLinkedList();
	List<BlockPos> checked = Lists.newArrayList();
	queue.add(pos);
	while (!queue.isEmpty()) {
		BlockPos current = queue.pop();
		@SuppressWarnings("unchecked") //safe because we only get the positions of fluid pipes
		TileFluidNode currentPipe = (TileFluidNode) world.getTileEntity(current)
		if (currentPipe.isOutput(pos, world))
				return Optional.of(current)
		checked.add(current)
		for (BlockPos pos: currentPipe.getNeighborPipes(pos, world)) {
			if (!checked.contains(pos))
					queue.add(pos)
		}
	}
	return Optional.absent<BlockPos>();
}

public boolean isOutput(BlockPos pos, World world) {
	// logic here
}