This extension does not have an associated header file.

This is a new section. (The text of the old 20.2 Network connection is subsumed into the new 20.3 TCP and UDP, below.)

Each socket type defined in OpenKODE core has some of the following characteristics:

If a socket type is connection based, then any communication is between two endpoints, one of which is the server (it calls kdSocketBind, kdSocketListen and kdSocketAccept), and the other is the client (it calls kdSocketConnect).

If a socket type is connectionless, then one device may send data to any other addressable device without connecting first.

If a socket type is reliable, then data sent arrives at its destination, uncorrupted and in order, otherwise an error is generated (although not necessarily by the function call that sent the lost data).

If a socket type is unreliable, then data sent does not necessarily arrive, or may arrive corrupted, or packets may arrive out of order. The application(s) must make their own arrangements to work round this.

If a socket type is stream oriented, then data is sent as a stream and the boundaries between different kdSocketSend or kdSocketSendTo calls are not preserved.

If a socket type is datagram oriented, then data is sent as a packet. The packet of data sent by a single kdSocketSend or kdSocketSendTo call is read as a single unit by a single kdSocketRecv or kdSocketRecvFrom call. If the receive call does not provide enough buffer space for the packet, then it is truncated and the truncated part is lost.

typedef struct KDSockaddr {
    KDuint16 family;
    union {
        KDSockaddrAfInATX sin;
    } data;
} KDSockaddr;

This is a new section, which also subsumes the old 20.3 Types.

An OpenKODE Core implementation may support neither, one or both of TCP and UDP sockets. The socket type constants for use in kdSocketCreate are:

#define KD_SOCK_TCP 64
#define KD_SOCK_UDP 65

A TCP socket is connection based, reliable and stream oriented.

A UDP socket is connectionless, unreliable and datagram oriented.

Both TCP and UDP use the IP addressing family, and contribute the sin field (of the type KDSockaddrAfInATX defined here) to the KDSockaddr data union:

#define KD_AF_INET 70
typedef struct KDSockaddrAfInATX {
    KDuint16 port;
    KDuint32 address;
} KDSockaddrAfInATX;

For a KDSockaddr addr where addr.family is KD_AF_INET, the fields are set as follows:

Any special signficance attached to certain ranges of IP addresses is implementation specific. In particular, there is no guarantee that there is a loopback interface accessed with the IP address 127.0.0.1.

Adding a new socket type could cause KDSockaddr to grow in size. This could cause problems for any vendor wanting to provide binary backwards compatibility between versions of its implementation.

To allow a vendor to implement binary backwards compatibility, changes need to be made to the definition of how much of the KDSockaddr struct needs to be readable or writable in any OpenKODE Core function that takes a KDSockaddr pointer as a parameter.

Therefore this extension specifies the following changes: