ddpType
#include <AppleTalk.h>
typedef struct ATDDPRec { Size Offset Description short abResult ; 2 2 Result code
long abUserReference; 4 4 For your use
short ddpType; 2 8 DDP protocol type
short ddpSocket 2 10 Source or listening socket
number
AddrBlock ddpAddress; 4 12 Destination or source socket address
short ddpReqCount; 2 16 Length of datagram data or buffer
size in bytes
short ddpActCount; 2 18 Number of frame data bytes
actually received
Ptr ddpDataPtr; 4 20 Pointer to frame data or pointer to buffer
short ddpNodeID; 2 24 original destination node ID
typedef ATDDPRec *ATDDPRecPtr;
typedef ATDDPRec **ATDDPRecHandle;
Notes: When a DDP datagram is sent, ddpReqCount indicates the size of the
datagram data in bytes and ddpDataPtr points to a buffer containing the
datagram data. DDPSocket specifies the socket from which the datagram
should be sent. DDPAddress is the internet address of the socket to which the
datagram should be sent:
The network number you specify in ddpAddress.aNet tells MMP whether to
create a long header (for an internet) or a short header (for a local network
only). A short DDP header will be sent if ddpAddress.aNet is 0 or equal to
the network number of the local network.
When a DDP datagram is received, ddpDataPtr points to a buffer in which
the incoming data can be stored and ddpReqCount indicates the size of the
buffer in bytes. The number of bytes actually sent or received is returned
in the ddpActCount field. DDPAddress is the internet address of the socket
from which the datagram was sent.
DDPType is the DDP protocol type of the datagram, and ddpSocket specifies
the socket that will receive the datagram.
Warning: DDP protocol types 1 through 15 and DDP socket numbers 1
through 63 are reserved by Apple for internal use. Socket numbers 64
through 127 are available for experimental use. Use of these experimental
sockets is not recommended for commercial products since there's no
mechanism for eliminating conflicting usage by different developers.
Using DDP
Before it can use a socket, the program must call DDPOpenSocket, which adds a socket and its socket listener to the socket table. When a program is
finished using a socket, call DDPCloseSocket, which removes the socket's entry from the socket table. To send a datagram via DDP, call DDPWrite. To receive datagrams, you have two choices:
to receive datagrams.
• Write you own socket listener and call DDPOpenSocket to install it. DDP will call your socket listener for every incoming datagram for that socket;
in this case, you should not call DDPRead.