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rpcgen(1) General Commands Manual rpcgen(1)

NAME
rpcgen - an RPC protocol compiler

SYNOPSIS
rpcgen infile
rpcgen [-Dname[=value]] [-T] [-K secs] infile
rpcgen -c|-h|-l|-m|-M|-t [-o outfile ] infile
rpcgen [-I] -s nettype [-o outfile] infile
rpcgen -n netid [-o outfile] infile

DESCRIPTION
rpcgen is a tool that generates C code to implement an RPC protocol. The input to rpcgen is
a language similar to C known as RPC Language (Remote Procedure Call Language).

rpcgen is normally used as in the first synopsis where it takes an input file and generates
up to four output files. If the infile is named proto.x, then rpcgen will generate a header
file in proto.h, XDR routines in proto_xdr.c, server-side stubs in proto_svc.c, and client-
side stubs in proto_clnt.c. With the -T option, it will also generate the RPC dispatch table
in proto_tbl.i. With the -Sc option, it will also generate sample code which would illus‐
trate how to use the remote procedures on the client side. This code would be created in
proto_client.c. With the -Ss option, it will also generate a sample server code which would
illustrate how to write the remote procedures. This code would be created in proto_server.c.

The server created can be started both by the port monitors (for example, inetd or listen) or
by itself. When it is started by a port monitor, it creates servers only for the transport
for which the file descriptor 0 was passed. The name of the transport must be specified by
setting up the environmental variable PM_TRANSPORT. When the server generated by rpcgen is
executed, it creates server handles for all the transports specified in NETPATH environment
variable, or if it is unset, it creates server handles for all the visible transports from
/etc/netconfig file. Note: the transports are chosen at run time and not at compile time.

When built for a port monitor (rpcgen -I), and that the server is self-started, it back‐
grounds itself by default. A special define symbol RPC_SVC_FG can be used to run the server
process in foreground.

The second synopsis provides special features which allow for the creation of more sophisti‐
cated RPC servers. These features include support for user provided #defines and RPC dis‐
patch tables. The entries in the RPC dispatch table contain:
• pointers to the service routine corresponding to that procedure,
• a pointer to the input and output arguments
• the size of these routines
A server can use the dispatch table to check authorization and then to execute the service
routine; a client library may use it to deal with the details of storage management and XDR
data conversion.

The other three synopses shown above are used when one does not want to generate all the out‐
put files, but only a particular one. Some examples of their usage is described in the EXAM‐
PLE section below. When rpcgen is executed with the -s option, it creates servers for that
particular class of transports. When executed with the -n option, it creates a server for
the transport specified by netid. If infile is not specified, rpcgen accepts the standard
input.

The C preprocessor, cc -E [see cc(1)], is run on the input file before it is actually inter‐
preted by rpcgen. For each type of output file, rpcgen defines a special preprocessor symbol
for use by the rpcgen programmer:

RPC_HDR defined when compiling into header files
RPC_XDR defined when compiling into XDR routines
RPC_SVC defined when compiling into server-side stubs
RPC_CLNT defined when compiling into client-side stubs
RPC_TBL defined when compiling into RPC dispatch tables

Any line beginning with `%' is passed directly into the output file, uninterpreted by rpcgen.

For every data type referred to in infile, rpcgen assumes that there exists a routine with
the string xdr_ prepended to the name of the data type. If this routine does not exist in
the RPC/XDR library, it must be provided. Providing an undefined data type allows customiza‐
tion of XDR routines.

The following options are available:

-a Generate all the files including sample code for client and server side.

-b This generates code for the SunOS4.1 style of rpc. It is for backward compatibility.
This is the default.

-5 This generates code for the SysVr4 style of rpc. It is used by the Transport Indepen‐
dent RPC that is in Svr4 systems. By default rpcgen generates code for SunOS4.1 stype
of rpc.

-c Compile into XDR routines.

-C Generate code in ANSI C. This option also generates code that could be compiled with
the C++ compiler. This is the default.

-k Generate code in K&R C. The default is ANSI C.

-Dname[=value]
Define a symbol name. Equivalent to the #define directive in the source. If no value
is given, value is defined as 1. This option may be specified more than once.

-h Compile into C data-definitions (a header file). -T option can be used in conjunction
to produce a header file which supports RPC dispatch tables.

-I Generate a service that can be started from inetd. The default is to generate a
static service that handles transports selected with -s. Using -I allows starting a
service by either method.

-K secs
By default, services created using rpcgen wait 120 seconds after servicing a request
before exiting. That interval can be changed using the -K flag. To create a server
that exits immediately upon servicing a request, -K 0 can be used. To create a server
that never exits, the appropriate argument is -K -1.

When monitoring for a server, some portmonitors, like listen(1M), always spawn a new
process in response to a service request. If it is known that a server will be used
with such a monitor, the server should exit immediately on completion. For such
servers, rpcgen should be used with -K -1.

-l Compile into client-side stubs.

-m Compile into server-side stubs, but do not generate a “main” routine. This option is
useful for doing callback-routines and for users who need to write their own “main”
routine to do initialization.

-M Generate multithread-safe stubs for passing arguments and results between rpcgen-gen‐
erated code and user written code. This option is useful for users who want to use
threads in their code.

-n netid
Compile into server-side stubs for the transport specified by netid. There should be
an entry for netid in the netconfig database. This option may be specified more than
once, so as to compile a server that serves multiple transports.

-N Use the newstyle of rpcgen. This allows procedures to have multiple arguments. It
also uses the style of parameter passing that closely resembles C. So, when passing an
argument to a remote procedure you do not have to pass a pointer to the argument but
the argument itself. This behaviour is different from the oldstyle of rpcgen generated
code. The newstyle is not the default case because of backward compatibility.

-o outfile
Specify the name of the output file. If none is specified, standard output is used
(-c, -h, -l, -m, -n, -s, -Sc, -Sm, -Ss, and -t modes only).

-s nettype
Compile into server-side stubs for all the transports belonging to the class nettype.
The supported classes are netpath, visible, circuit_n, circuit_v, datagram_n, data‐‐
gram_v, tcp, and udp [see rpc(3N) for the meanings associated with these classes].
This option may be specified more than once. Note: the transports are chosen at run
time and not at compile time.

-Sc Generate sample code to show the use of remote procedure and how to bind to the server
before calling the client side stubs generated by rpcgen.

-Sm Generate a sample Makefile which can be used for compiling the application.

-Ss Generate skeleton code for the remote procedures on the server side. You would need to
fill in the actual code for the remote procedures.

-t Compile into RPC dispatch table.

-T Generate the code to support RPC dispatch tables.

The options -c, -h, -l, -m, -s and -t are used exclusively to generate a particular type of
file, while the options -D and -T are global and can be used with the other options.

NOTES
The RPC Language does not support nesting of structures. As a work-around, structures can be
declared at the top-level, and their name used inside other structures in order to achieve
the same effect.

Name clashes can occur when using program definitions, since the apparent scoping does not
really apply. Most of these can be avoided by giving unique names for programs, versions,
procedures and types.

The server code generated with -n option refers to the transport indicated by netid and hence
is very site specific.

EXAMPLE
The following example:

$ rpcgen -T prot.x

generates the five files: prot.h, prot_clnt.c, prot_svc.c, prot_xdr.c and prot_tbl.i.

The following example sends the C data-definitions (header file) to the standard output.

$ rpcgen -h prot.x

To send the test version of the -DTEST, server side stubs for all the transport belonging to
the class datagram_n to standard output, use:

$ rpcgen -s datagram_n -DTEST prot.x

To create the server side stubs for the transport indicated by netid tcp, use:

$ rpcgen -n tcp -o prot_svc.c prot.x