3.2 Port Mapper Operation

The portmapper program currently supports two protocols (UDP and TCP). The portmapper is contacted by talking to it on assigned port number 111 (SUNRPC) on either of these protocols.

The following is a description of each of the portmapper procedures:

PMAPPROC_NULL:

This procedure does no work. By convention, procedure zero of any protocol takes no parameters and returns no results.

PMAPPROC_SET:

When a program first becomes available on a machine, it registers itself with the port mapper program on the same machine. The program passes its program number "prog", version number "vers", transport protocol number "prot", and the port "port" on which it awaits service request. The procedure returns a boolean reply whose value is "TRUE" if the procedure successfully established the mapping and "FALSE" otherwise. The procedure refuses to establish a mapping if one already exists for the tuple "(prog, vers, prot)".

PMAPPROC_UNSET:

When a program becomes unavailable, it should unregister itself with the port mapper program on the same machine. The parameters and results have meanings identical to those of "PMAPPROC_SET". The protocol and port number fields of the argument are ignored.

PMAPPROC_GETPORT:

Given a program number "prog", version number "vers", and transport protocol number "prot", this procedure returns the port number on which the program is awaiting call requests. A port value of zeros means the program has not been registered. The "port" field of the argument is ignored.

PMAPPROC_DUMP:

This procedure enumerates all entries in the port mapper's database. The procedure takes no parameters and returns a list of program, version, protocol, and port values.

PMAPPROC_CALLIT:

This procedure allows a client to call another remote procedure on the same machine without knowing the remote procedure's port number. It is intended for supporting broadcasts to arbitrary remote programs via the well-known port mapper's port. The parameters "prog", "vers", "proc", and the bytes of "args" are the program number, version number, procedure number, and parameters of the remote procedure. Note:

1. This procedure only sends a reply if the procedure was successfully executed and is silent (no reply) otherwise.

2. The port mapper communicates with the remote program using UDP only.

The procedure returns the remote program's port number, and the reply is the reply of the remote procedure.