RPCL Programs
You declare RPC programs using the following syntax:
program-definition:
"program" program-ident "{"
version-list
"}" "=" value;
version-list:
version ";"
version ";" version-list
version:
"version" version-ident "{"
procedure-list
"}" "=" value;
procedure-list:
procedure ";"
procedure ";" procedure-list
procedure:
type-ident procedure-ident "(" type-ident ")" "=" value;
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When the -N option is specified, rpcgen
also recognizes the following syntax.
procedure:
type-ident procedure-ident "(" type-ident-list ")" "=" value;
type-ident-list:
type-ident
type-ident "," type-ident-list
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Example:
/*
* time.x: Get or set the time. Time is represented as seconds
* since 0:00, January 1, 1970.
*/
program TIMEPROG {
version TIMEVERS {
unsigned int TIMEGET(void) = 1;
void TIMESET(unsigned) = 2;
} = 1;
} = 0x20000044;
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Note that the void argument type means that no argument
is passed.
The following file compiles into these #define statements
in the output header file.
#define TIMEPROG 0x20000044
#define TIMEVERS 1
#define TIMEGET 1
#define TIMESET 2
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RPCL Special Cases
Several exceptions to the RPC language rules follow.
RPCL C-style Mode
The features of the C-style mode of rpcgen have implications
for the passing of void arguments. No arguments need be
passed if their value is void.
RPCL Booleans
C has no built-in Boolean type. However, the RPC library uses a Boolean
type called bool_t that is either TRUE or FALSE. Parameters declared as type bool in XDR language
are compiled into bool_t in the output header file.
Example:
bool married; --> bool_t married;
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RPCL Strings
The C language has no built-in string type, but instead uses the null-terminated char * convention. In C, strings are usually treated as null-terminated
single-dimensional arrays.
In XDR language, strings are declared using the string
keyword, and compiled into type char * in the output header file.
The maximum size contained in the angle brackets specifies the maximum number
of characters allowed in the strings, not counting the NULL
character. You can omit the maximum size, indicating a string of arbitrary
length.
Examples:
string name<32>; --> char *name;
string longname<>; --> char *longname;
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NULL strings cannot be passed; however, a zero-length
string (that is, just the terminator or NULL byte) can
be passed.
RPCL Opaque Data
Opaque data is used in XDR to describe untyped data, that is, sequences
of arbitrary bytes. You can declare opaque data either as a fixed-length or
variable-length array.
Examples:
opaque diskblock[512]; --> char diskblock[512];
opaque filedata<1024>; --> struct {
u_int filedata_len;
char *filedata_val;
} filedata;
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RPCL Voids
In a void declaration, the variable is not named. The declaration is
just void and nothing else. Void declarations can only
occur in two places: union definitions and program definitions as the argument
or result of a remote procedure; for example, no arguments are passed.
rpcbind Protocol
rpcbind maps RPC program and version numbers to universal
addresses, thus making dynamic binding of remote programs possible.
rpcbind is bound to a well-known address of each
supported transport, and other programs register their dynamically allocated
transport addresses with it. rpcbind then makes those addresses
publicly available. Universal addresses are string representations of the
transport-dependent address. They are defined by the addressing authority
of the given transport.
rpcbind also aids in broadcast RPC. RPC programs
have different addresses on different machines, so direct broadcasts to all
these programs are not possible. rpcbind, however, has
a well-known address. So, to broadcast to a given program, the client sends
its message to the rpcbind process on the machine it chooses
to reach. rpcbind picks up the broadcast and calls the
local service specified by the client. When rpcbind gets
a reply from the local service, it passes the reply on to the client.
The following code example shows the rpcbind Protocol
Specification in RPC Language.
Example B-5 rpcbind Protocol Specification in RPC Language
/*
* rpcb_prot.x
* RPCBIND protocol in rpc language
*/
/*
* A mapping of (program, version, network ID) to universal
address
*/
struct rpcb {
rpcproc_t r_prog; /* program number */
rpcvers_t r_vers; /* version number */
string r_netid<>; /* network id */
string r_addr<>; /* universal address */
string r_owner<>; /* owner of this service */ };
/* A list of mappings */
struct rpcblist {
rpcb rpcb_map;
struct rpcblist *rpcb_next;
};
/* Arguments of remote calls */
struct rpcb_rmtcallargs {
rpcprog_t prog; /* program number */
rpcvers_t vers; /* version number */
rpcproc_t proc; /* procedure number */
opaque args<>; /* argument */
};
/* Results of the remote call */
struct rpcb_rmtcallres {
string addr<>; /* remote universal address */
opaque results<>; /* result */
};
/*
* rpcb_entry contains a merged address of a service on a
particular
* transport, plus associated netconfig information. A list of
* rpcb_entrys is returned by RPCBPROC_GETADDRLIST. See
netconfig.h
* for values used in r_nc_* fields.
*/
struct rpcb_entry {
string r_maddr<>; /* merged address of service */
string r_nc_netid<>; /* netid field */
unsigned int r_nc_semantics; /* semantics of transport */
string r_nc_protofmly<>; /* protocol family */
string r_nc_proto<>; /* protocol name */
};
/* A list of addresses supported by a service. */
struct rpcb_entry_list {
rpcb_entry rpcb_entry_map;
struct rpcb_entry_list *rpcb_entry_next;
};
typedef rpcb_entry_list *rpcb_entry_list_ptr;
/* rpcbind statistics */
const rpcb_highproc_2 = RPCBPROC_CALLIT;
const rpcb_highproc_3 = RPCBPROC_TADDR2UADDR;
const rpcb_highproc_4 = RPCBPROC_GETSTAT;
const RPCBSTAT_HIGHPROC = 13; /* # of procs in rpcbind V4 plus
one */
const RPCBVERS_STAT = 3; /* provide only for rpcbind V2, V3 and
V4 */
const RPCBVERS_4_STAT = 2;
const RPCBVERS_3_STAT = 1;
const RPCBVERS_2_STAT = 0;
/* Link list of all the stats about getport and getaddr */
struct rpcbs_addrlist {
rpcprog_t prog;
rpcvers_t vers;
int success;
int failure;
string netid<>;
struct rpcbs_addrlist *next;
};
/* Link list of all the stats about rmtcall */
struct rpcbs_rmtcalllist {
rpcprog_t prog;
rpcvers_t vers;
rpcproc_t proc;
int success;
int failure;
int indirect; /* whether callit or indirect */
string netid<>;
struct rpcbs_rmtcalllist *next;
};
typedef int rpcbs_proc[RPCBSTAT_HIGHPROC];
typedef rpcbs_addrlist *rpcbs_addrlist_ptr;
typedef rpcbs_rmtcalllist *rpcbs_rmtcalllist_ptr;
struct rpcb_stat {
rpcbs_proc info;
int setinfo;
int unsetinfo;
rpcbs_addrlist_ptr addrinfo;
rpcbs_rmtcalllist_ptr rmtinfo;
};
/*
* One rpcb_stat structure is returned for each version of rpcbind
* being monitored.
*/
typedef rpcb_stat rpcb_stat_byvers[RPCBVERS_STAT];
/* rpcbind procedures */
program RPCBPROG {
version RPCBVERS {
void
RPCBPROC_NULL(void) = 0;
/*
* Registers the tuple [r_prog, r_vers, r_addr, r_owner,
* r_netid]. The rpcbind server accepts requests for this
* procedure on only the loopback transport for security
* reasons. Returns TRUE if successful, FALSE on failure.
*/
bool
RPCBPROC_SET(rpcb) = 1;
/*
* Unregisters the tuple [r_prog, r_vers, r_owner, r_netid].
* If vers is zero, all versions are
unregistered. The rpcbind
* server accepts requests for this procedure on only the
* loopback transport for security reasons. Returns TRUE if
* successful, FALSE on failure.
*/
bool
RPCBPROC_UNSET(rpcb) = 2;
/*
* Returns the universal address where the triple [r_prog,
* r_vers, r_netid] is registered. If r_addr specified,
* return a universal address merged on r_addr. Ignores
* r_owner. Returns FALSE on failure.
*/
string
RPCBPROC_GETADDR(rpcb) = 3;
/* Returns a list of all mappings. */
rpcblist
RPCBPROC_DUMP(void) = 4;
/*
* Calls the procedure on the remote machine. If it is not
* registered, this procedure IS quiet; that is, it DOES NOT
* return error information.
*/
rpcb_rmtcallres
RPCBPROC_CALLIT(rpcb_rmtcallargs) = 5;
/*
* Returns the time on the rpcbind server's system.
*/
unsigned int
RPCBPROC_GETTIME(void) = 6;
struct netbuf
RPCBPROC_UADDR2TADDR(string) = 7;
string
RPCBPROC_TADDR2UADDR(struct netbuf) = 8;
} = 3;
version RPCBVERS4 {
bool
RPCBPROC_SET(rpcb) = 1;
bool
RPCBPROC_UNSET(rpcb) = 2;
string
RPCBPROC_GETADDR(rpcb) = 3;
rpcblist_ptr
RPCBPROC_DUMP(void) = 4;
/*
* NOTE: RPCBPROC_BCAST has the same functionality as CALLIT;
* the new name is
intended to indicate that this procedure
* should be used for broadcast RPC, and RPCBPROC_INDIRECT
* should be used for indirect calls.
*/
rpcb_rmtcallres
RPCBPROC_BCAST(rpcb_rmtcallargs) = RPCBPROC_CALLIT;
unsigned int
RPCBPROC_GETTIME(void) = 6;
struct netbuf
RPCBPROC_UADDR2TADDR(string) = 7;
string
RPCBPROC_TADDR2UADDR(struct netbuf) = 8;
/*
* Same as RPCBPROC_GETADDR except that if the given version
* number is not available, the address is not returned.
*/
string
RPCBPROC_GETVERSADDR(rpcb) = 9;
/*
* Calls the procedure on the remote machine. If it is not
* registered, this procedure IS NOT quiet; that is, it DOES
* return error information.
*/
rpcb_rmtcallres
RPCBPROC_INDIRECT(rpcb_rmtcallargs) = 10;
/*
* Same as RPCBPROC_GETADDR except that it returns a list of
* addresses registered for the combination (prog, vers).
*/
rpcb_entry_list_ptr
RPCBPROC_GETADDRLIST(rpcb) = 11;
/*
* Returns statistics about the rpcbind server's activity.
*/
rpcb_stat_byvers
RPCBPROC_GETSTAT(void) = 12;
} = 4;
} = 100000;
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