def handle(self, pkt, raddress, rport):
        "Handle an initial RRQ packet as a server."
        log.debug("In TftpStateServerRecvRRQ.handle")
        sendoack = self.serverInitial(pkt, raddress, rport)
        path = self.full_path
        log.info("Opening file %s for reading" % path)
        if os.path.exists(path):
            # Note: Open in binary mode for win32 portability, since win32
            # blows.
            self.context.fileobj = open(path, "rb")
        elif self.context.dyn_file_func:
            log.debug("No such file %s but using dyn_file_func", path)
            self.context.fileobj = \
                self.context.dyn_file_func(self.context.file_to_transfer, raddress=raddress, rport=rport)

            if self.context.fileobj is None:
                log.debug("dyn_file_func returned 'None', treating as "
                          "FileNotFound")
                self.sendError(TftpErrors.FileNotFound)
                raise TftpException("File not found: %s" % path)
        else:
            log.warn("File not found: %s", path)
            self.sendError(TftpErrors.FileNotFound)
            raise TftpException("File not found: {}".format(path))

        # Options negotiation.
        if sendoack and 'tsize' in self.context.options:
            # getting the file size for the tsize option. As we handle
            # file-like objects and not only real files, we use this seeking
            # method instead of asking the OS
            self.context.fileobj.seek(0, os.SEEK_END)
            tsize = str(self.context.fileobj.tell())
            self.context.fileobj.seek(0, 0)
            self.context.options['tsize'] = tsize

        if sendoack:
            # Note, next_block is 0 here since that's the proper
            # acknowledgement to an OACK.
            # FIXME: perhaps we do need a TftpStateExpectOACK class...
            self.sendOACK()
            # Note, self.context.next_block is already 0.
        else:
            self.context.next_block = 1
            log.debug("No requested options, starting send...")
            self.context.pending_complete = self.sendDAT()
        # Note, we expect an ack regardless of whether we sent a DAT or an
        # OACK.
        return TftpStateExpectACK(self.context)
Handle an initial RRQ packet as a server.