Network Clients - Java - page 525

buffer = new new byte byte [ PACKET_SIZE ];

outp = new new DatagramPacket ( buffer , PACKET_SIZE , servAddr , TFTP_PORT );

inp = new

new DatagramPacket ( buffer , PACKET_SIZE );

}

/* Build a TFTP Read Request packet. This is messy because the
* fields have variable length. Numbers must be in
* network order, too; fortunately Java just seems
* naturally smart enough :-) to use network byte order.
*/
void void readFile ( String path ) throws throws IOException {

buffer [ 0 ] = 0 ;
buffer [ OFFSET_REQUEST ] = OP_RRQ ;

// read request

int int p = 2 ; // number of chars into buffer

// Convert filename String to bytes in buffer , using "p" as an
// offset indicator to get all the bits of this request
// in exactly the right spot.
byte byte [] bTemp = path . getBytes (); // i.e., ASCII

System . arraycopy ( bTemp , 0 , buffer , p , path . length ());
p += path . length ();
buffer [ p ++] = 0 ;

// null byte terminates string

// Similarly, convert MODE ("stream" or "octet") to bytes in buffer
bTemp = MODE . getBytes (); // i.e., ASCII
System . arraycopy ( bTemp , 0 , buffer , p , MODE . length ());
p += MODE . length ();
buffer [ p ++] = 0 ;

// null terminate

/* Send Read Request to tftp server */
outp . setLength ( p );
sock . send ( outp );

/* Loop reading data packets from the server until a short
* packet arrives; this indicates the end of the file.
*/
int int len = 0 ;

ddo {

sock . receive ( inp );
iif ( debug )
System . err . println (
"Packet # " + Byte . toString ( buffer [ OFFSET_PACKETNUM ])+
"RESPONSE CODE " + Byte . toString ( buffer [ OFFSET_REQUEST ]));
iif ( buffer [ OFFSET_REQUEST ] == OP_ERROR ) {
System . err . println ( "rcat ERROR: " +
new

new String ( buffer , 4 , inp . getLength ()- 4 ));