NAME |LIBRARY |SYNOPSIS AND DESCRIPTION |ATTRIBUTES |SEE ALSO |COLOPHON | |
rpc(3) Library Functions Manualrpc(3)rpc - library routines for remote procedure calls
Standard C library (libc,-lc)
These routines allow C programs to make procedure calls on other machines across the network. First, the client calls a procedure to send a data packet to the server. Upon receipt of the packet, the server calls a dispatch routine to perform the requested service, and then sends back a reply. Finally, the procedure call returns to the client. To take use of these routines, include the header file<rpc/rpc.h>. The prototypes below make use of the following types:typedef intbool_t;typedef typeof(bool_t (XDR *, void *, ...)) *xdrproc_t;typedef typeof(bool_t (caddr_tresp, struct sockaddr_in *raddr)*resultproc_t; See the header files for the declarations of theAUTH,CLIENT,SVCXPRT, andXDR types.void auth_destroy(AUTH *auth); A macro that destroys the authentication information associated withauth. Destruction usually involves deallocation of private data structures. The use ofauth is undefined after callingauth_destroy().AUTH *authnone_create(void); Create and return an RPC authentication handle that passes nonusable authentication information with each remote procedure call. This is the default authentication used by RPC.AUTH *authunix_create(char *host, uid_tuid, gid_tgid,intn, gid_taup_gids[n]); Create and return an RPC authentication handle that contains authentication information. The parameterhost is the name of the machine on which the information was created;uid is the user's user ID;gid is the user's current group ID;n andaup_gids refer to a counted array of groups to which the user belongs. It is easy to impersonate a user.AUTH *authunix_create_default(void); Callsauthunix_create() with the appropriate parameters.int callrpc(char *host, unsigned longprognum,unsigned longversnum, unsigned longprocnum,xdrproc_tinproc, const char *in,xdrproc_toutproc, char *out); Call the remote procedure associated withprognum,versnum, andprocnum on the machine,host. The parameterin is the address of the procedure's argument(s), andout is the address of where to place the result(s);inproc is used to encode the procedure's parameters, andoutproc is used to decode the procedure's results. This routine returns zero if it succeeds, or the value ofenum clnt_statcast to an integer if it fails. The routineclnt_perrno() is handy for translating failure statuses into messages. Warning: calling remote procedures with this routine uses UDP/IP as a transport; seeclntudp_create() for restrictions. You do not have control of timeouts or authentication using this routine.enum clnt_stat clnt_broadcast(unsigned longprognum,unsigned longversnum, unsigned longprocnum,xdrproc_tinproc, char *in,xdrproc_toutproc, char *out,resultproc_teachresult); Likecallrpc(), except the call message is broadcast to all locally connected broadcast nets. Each time it receives a response, this routine callseachresult(), whose form is:eachresult(char *out, struct sockaddr_in *addr); whereout is the same asout passed toclnt_broadcast(), except that the remote procedure's output is decoded there;addr points to the address of the machine that sent the results. Ifeachresult() returns zero,clnt_broadcast() waits for more replies; otherwise it returns with appropriate status. Warning: broadcast sockets are limited in size to the maximum transfer unit of the data link. For ethernet, this value is 1500 bytes.enum clnt_stat clnt_call(CLIENT *clnt, unsigned longprocnum,xdrproc_tinproc, char *in,xdrproc_toutproc, char *out,struct timevaltout); A macro that calls the remote procedureprocnum associated with the client handle,clnt, which is obtained with an RPC client creation routine such asclnt_create(). The parameterin is the address of the procedure's argument(s), andout is the address of where to place the result(s);inproc is used to encode the procedure's parameters, andoutproc is used to decode the procedure's results;tout is the time allowed for results to come back.clnt_destroy(CLIENT *clnt); A macro that destroys the client's RPC handle. Destruction usually involves deallocation of private data structures, includingclnt itself. Use ofclnt is undefined after callingclnt_destroy(). If the RPC library opened the associated socket, it will close it also. Otherwise, the socket remains open.CLIENT *clnt_create(const char *host, unsigned longprog,unsigned longvers, const char *proto); Generic client creation routine.host identifies the name of the remote host where the server is located.proto indicates which kind of transport protocol to use. The currently supported values for this field are “udp” and “tcp”. Default timeouts are set, but can be modified usingclnt_control(). Warning: using UDP has its shortcomings. Since UDP-based RPC messages can hold only up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results.bool_t clnt_control(CLIENT *cl, intreq, char *info); A macro used to change or retrieve various information about a client object.req indicates the type of operation, andinfo is a pointer to the information. For both UDP and TCP, the supported values ofreq and their argument types and what they do are:CLSET_TIMEOUTstruct timeval // set total timeoutCLGET_TIMEOUTstruct timeval // get total timeout Note: if you set the timeout usingclnt_control(), the timeout parameter passed toclnt_call() will be ignored in all future calls.CLGET_SERVER_ADDRstruct sockaddr_in // get server's address The following operations are valid for UDP only:CLSET_RETRY_TIMEOUTstruct timeval // set the retry timeoutCLGET_RETRY_TIMEOUTstruct timeval // get the retry timeout The retry timeout is the time that "UDP RPC" waits for the server to reply before retransmitting the request.clnt_freeres(CLIENT *clnt, xdrproc_toutproc, char *out); A macro that frees any data allocated by the RPC/XDR system when it decoded the results of an RPC call. The parameterout is the address of the results, andoutproc is the XDR routine describing the results. This routine returns one if the results were successfully freed, and zero otherwise.void clnt_geterr(CLIENT *clnt, struct rpc_err *errp); A macro that copies the error structure out of the client handle to the structure at addresserrp.void clnt_pcreateerror(const char *s); Print a message to standard error indicating why a client RPC handle could not be created. The message is prepended with strings and a colon. Used when aclnt_create(),clntraw_create(),clnttcp_create(), orclntudp_create() call fails.void clnt_perrno(enum clnt_statstat); Print a message to standard error corresponding to the condition indicated bystat. Used aftercallrpc().clnt_perror(CLIENT *clnt, const char *s); Print a message to standard error indicating why an RPC call failed;clnt is the handle used to do the call. The message is prepended with strings and a colon. Used afterclnt_call().char *clnt_spcreateerror(const char *s); Likeclnt_pcreateerror(), except that it returns a string instead of printing to the standard error. Bugs: returns pointer to static data that is overwritten on each call.char *clnt_sperrno(enum clnt_statstat); Take the same arguments asclnt_perrno(), but instead of sending a message to the standard error indicating why an RPC call failed, return a pointer to a string which contains the message. The string ends with a NEWLINE.clnt_sperrno() is used instead ofclnt_perrno() if the program does not have a standard error (as a program running as a server quite likely does not), or if the programmer does not want the message to be output withprintf(3), or if a message format different than that supported byclnt_perrno() is to be used. Note: unlikeclnt_sperror() andclnt_spcreateerror(),clnt_sperrno() returns pointer to static data, but the result will not get overwritten on each call.char *clnt_sperror(CLIENT *rpch, const char *s); Likeclnt_perror(), except that (likeclnt_sperrno()) it returns a string instead of printing to standard error. Bugs: returns pointer to static data that is overwritten on each call.CLIENT *clntraw_create(unsigned longprognum, unsigned longversnum); This routine creates a toy RPC client for the remote programprognum, versionversnum. The transport used to pass messages to the service is actually a buffer within the process's address space, so the corresponding RPC server should live in the same address space; seesvcraw_create(). This allows simulation of RPC and acquisition of RPC overheads, such as round trip times, without any kernel interference. This routine returns NULL if it fails.CLIENT *clnttcp_create(struct sockaddr_in *addr,unsigned longprognum, unsigned longversnum,int *sockp, unsigned intsendsz, unsigned intrecvsz); This routine creates an RPC client for the remote programprognum, versionversnum; the client uses TCP/IP as a transport. The remote program is located at Internet address*addr. Ifaddr->sin_port is zero, then it is set to the actual port that the remote program is listening on (the remoteportmapservice is consulted for this information). The parametersockp is a socket; if it isRPC_ANYSOCK, then this routine opens a new one and setssockp. Since TCP-based RPC uses buffered I/O, the user may specify the size of the send and receive buffers with the parameterssendsz andrecvsz; values of zero choose suitable defaults. This routine returns NULL if it fails.CLIENT *clntudp_create(struct sockaddr_in *addr,unsigned longprognum, unsigned longversnum,struct timevalwait, int *sockp); This routine creates an RPC client for the remote programprognum, versionversnum; the client uses use UDP/IP as a transport. The remote program is located at Internet addressaddr. Ifaddr->sin_port is zero, then it is set to actual port that the remote program is listening on (the remoteportmapservice is consulted for this information). The parametersockp is a socket; if it isRPC_ANYSOCK, then this routine opens a new one and setssockp. The UDP transport resends the call message in intervals ofwait time until a response is received or until the call times out. The total time for the call to time out is specified byclnt_call(). Warning: since UDP-based RPC messages can hold only up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results.CLIENT *clntudp_bufcreate(struct sockaddr_in *addr,unsigned longprognum, unsigned longversnum,struct timevalwait, int *sockp,unsigned intsendsize, unsigned intrecosize); This routine creates an RPC client for the remote programprognum, onversnum; the client uses use UDP/IP as a transport. The remote program is located at Internet addressaddr. Ifaddr->sin_port is zero, then it is set to actual port that the remote program is listening on (the remoteportmapservice is consulted for this information). The parametersockp is a socket; if it isRPC_ANYSOCK, then this routine opens a new one and setssockp. The UDP transport resends the call message in intervals ofwait time until a response is received or until the call times out. The total time for the call to time out is specified byclnt_call(). This allows the user to specify the maximum packet size for sending and receiving UDP-based RPC messages.void get_myaddress(struct sockaddr_in *addr); Stuff the machine's IP address into*addr, without consulting the library routines that deal with/etc/hosts. The port number is always set tohtons(PMAPPORT).struct pmaplist *pmap_getmaps(struct sockaddr_in *addr); A user interface to theportmapservice, which returns a list of the current RPC program-to-port mappings on the host located at IP address*addr. This routine can return NULL. The commandrpcinfo -p uses this routine.unsigned short pmap_getport(struct sockaddr_in *addr,unsigned longprognum, unsigned longversnum,unsigned intprotocol); A user interface to theportmapservice, which returns the port number on which waits a service that supports program numberprognum, versionversnum, and speaks the transport protocol associated withprotocol. The value ofprotocol is most likelyIPPROTO_UDPorIPPROTO_TCP. A return value of zero means that the mapping does not exist or that the RPC system failed to contact the remoteportmapservice. In the latter case, the global variablerpc_createerr contains the RPC status.enum clnt_stat pmap_rmtcall(struct sockaddr_in *addr,unsigned longprognum, unsigned longversnum,unsigned longprocnum,xdrproc_tinproc, char *in,xdrproc_toutproc, char *out,struct timevaltout, unsigned long *portp); A user interface to theportmapservice, which instructsportmapon the host at IP address*addr to make an RPC call on your behalf to a procedure on that host. The parameter*portp will be modified to the program's port number if the procedure succeeds. The definitions of other parameters are discussed incallrpc() andclnt_call(). This procedure should be used for a “ping” and nothing else. See alsoclnt_broadcast().bool_t pmap_set(unsigned longprognum, unsigned longversnum,intprotocol, unsigned shortport); A user interface to theportmapservice, which establishes a mapping between the triple [prognum,versnum,protocol] andport on the machine'sportmapservice. The value ofprotocol is most likelyIPPROTO_UDPorIPPROTO_TCP. This routine returns one if it succeeds, zero otherwise. Automatically done bysvc_register().bool_t pmap_unset(unsigned longprognum, unsigned longversnum); A user interface to theportmapservice, which destroys all mapping between the triple [prognum,versnum,*] andportson the machine'sportmapservice. This routine returns one if it succeeds, zero otherwise.int registerrpc(unsigned longprognum, unsigned longversnum,unsigned longprocnum, typeof(char *(char *)) *procname,xdrproc_tinproc, xdrproc_toutproc); Register procedureprocname with the RPC service package. If a request arrives for programprognum, versionversnum, and procedureprocnum,procname is called with a pointer to its parameter(s);procname should return a pointer to its static result(s);inproc is used to decode the parameters whileoutproc is used to encode the results. This routine returns zero if the registration succeeded, -1 otherwise. Warning: remote procedures registered in this form are accessed using the UDP/IP transport; seesvcudp_create() for restrictions.struct rpc_createerrrpc_createerr; A global variable whose value is set by any RPC client creation routine that does not succeed. Use the routineclnt_pcreateerror() to print the reason why.void svc_destroy(SVCXPRT *xprt); A macro that destroys the RPC service transport handle,xprt. Destruction usually involves deallocation of private data structures, includingxprt itself. Use ofxprt is undefined after calling this routine.fd_setsvc_fdset; A global variable reflecting the RPC service side's read file descriptor bit mask; it is suitable as a parameter to theselect(2) system call. This is of interest only if a service implementor does their own asynchronous event processing, instead of callingsvc_run(). This variable is read-only (do not pass its address toselect(2)!), yet it may change after calls tosvc_getreqset() or any creation routines.intsvc_fds; Similar tosvc_fdset, but limited to 32 file descriptors. This interface is obsoleted bysvc_fdset.svc_freeargs(SVCXPRT *xprt, xdrproc_tinproc, char *in); A macro that frees any data allocated by the RPC/XDR system when it decoded the arguments to a service procedure usingsvc_getargs(). This routine returns 1 if the results were successfully freed, and zero otherwise.svc_getargs(SVCXPRT *xprt, xdrproc_tinproc, char *in); A macro that decodes the arguments of an RPC request associated with the RPC service transport handle,xprt. The parameterin is the address where the arguments will be placed;inproc is the XDR routine used to decode the arguments. This routine returns one if decoding succeeds, and zero otherwise.struct sockaddr_in *svc_getcaller(SVCXPRT *xprt); The approved way of getting the network address of the caller of a procedure associated with the RPC service transport handle,xprt.void svc_getreqset(fd_set *rdfds); This routine is of interest only if a service implementor does not callsvc_run(), but instead implements custom asynchronous event processing. It is called when theselect(2) system call has determined that an RPC request has arrived on some RPC socket(s);rdfds is the resultant read file descriptor bit mask. The routine returns when all sockets associated with the value ofrdfds have been serviced.void svc_getreq(intrdfds); Similar tosvc_getreqset(), but limited to 32 file descriptors. This interface is obsoleted bysvc_getreqset().bool_t svc_register(SVCXPRT *xprt, unsigned longprognum,unsigned longversnum,typeof(void (struct svc_req *, SVCXPRT *)) *dispatch,unsigned longprotocol); Associatesprognum andversnum with the service dispatch procedure,dispatch. Ifprotocol is zero, the service is not registered with theportmapservice. Ifprotocol is nonzero, then a mapping of the triple [prognum,versnum,protocol] toxprt->xp_port is established with the localportmapservice (generallyprotocol is zero,IPPROTO_UDPorIPPROTO_TCP). The proceduredispatch has the following form: dispatch(struct svc_req *request, SVCXPRT *xprt); Thesvc_register() routine returns one if it succeeds, and zero otherwise.void svc_run(void); This routine never returns. It waits for RPC requests to arrive, and calls the appropriate service procedure usingsvc_getreq() when one arrives. This procedure is usually waiting for aselect(2) system call to return.bool_t svc_sendreply(SVCXPRT *xprt, xdrproc_toutproc, char *out); Called by an RPC service's dispatch routine to send the results of a remote procedure call. The parameterxprt is the request's associated transport handle;outproc is the XDR routine which is used to encode the results; andout is the address of the results. This routine returns one if it succeeds, zero otherwise.void svc_unregister(unsigned longprognum, unsigned longversnum); Remove all mapping of the double [prognum,versnum] to dispatch routines, and of the triple [prognum,versnum,*] to port number.void svcerr_auth(SVCXPRT *xprt, enum auth_statwhy); Called by a service dispatch routine that refuses to perform a remote procedure call due to an authentication error.void svcerr_decode(SVCXPRT *xprt); Called by a service dispatch routine that cannot successfully decode its parameters. See alsosvc_getargs().void svcerr_noproc(SVCXPRT *xprt); Called by a service dispatch routine that does not implement the procedure number that the caller requests.void svcerr_noprog(SVCXPRT *xprt); Called when the desired program is not registered with the RPC package. Service implementors usually do not need this routine.void svcerr_progvers(SVCXPRT *xprt, unsigned longlow_vers,unsigned longhigh_vers); Called when the desired version of a program is not registered with the RPC package. Service implementors usually do not need this routine.void svcerr_systemerr(SVCXPRT *xprt); Called by a service dispatch routine when it detects a system error not covered by any particular protocol. For example, if a service can no longer allocate storage, it may call this routine.void svcerr_weakauth(SVCXPRT *xprt); Called by a service dispatch routine that refuses to perform a remote procedure call due to insufficient authentication parameters. The routine callssvcerr_auth(xprt, AUTH_TOOWEAK).SVCXPRT *svcfd_create(intfd, unsigned intsendsize,unsigned intrecvsize); Create a service on top of any open file descriptor. Typically, this file descriptor is a connected socket for a stream protocol such as TCP.sendsize andrecvsize indicate sizes for the send and receive buffers. If they are zero, a reasonable default is chosen.SVCXPRT *svcraw_create(void); This routine creates a toy RPC service transport, to which it returns a pointer. The transport is really a buffer within the process's address space, so the corresponding RPC client should live in the same address space; seeclntraw_create(). This routine allows simulation of RPC and acquisition of RPC overheads (such as round trip times), without any kernel interference. This routine returns NULL if it fails.SVCXPRT *svctcp_create(intsock, unsigned intsend_buf_size,unsigned intrecv_buf_size); This routine creates a TCP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the socketsock, which may beRPC_ANYSOCK, in which case a new socket is created. If the socket is not bound to a local TCP port, then this routine binds it to an arbitrary port. Upon completion,xprt->xp_sock is the transport's socket descriptor, andxprt->xp_port is the transport's port number. This routine returns NULL if it fails. Since TCP-based RPC uses buffered I/O, users may specify the size of buffers; values of zero choose suitable defaults.SVCXPRT *svcudp_bufcreate(intsock, unsigned intsendsize,unsigned intrecosize); This routine creates a UDP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the socketsock, which may beRPC_ANYSOCK, in which case a new socket is created. If the socket is not bound to a local UDP port, then this routine binds it to an arbitrary port. Upon completion,xprt->xp_sock is the transport's socket descriptor, andxprt->xp_port is the transport's port number. This routine returns NULL if it fails. This allows the user to specify the maximum packet size for sending and receiving UDP-based RPC messages.SVCXPRT *svcudp_create(intsock); This call is equivalent tosvcudp_bufcreate(sock,SZ,SZ) for some default sizeSZ.bool_t xdr_accepted_reply(XDR *xdrs, struct accepted_reply *ar); Used for encoding RPC reply messages. This routine is useful for users who wish to generate RPC-style messages without using the RPC package.bool_t xdr_authunix_parms(XDR *xdrs, struct authunix_parms *aupp); Used for describing UNIX credentials. This routine is useful for users who wish to generate these credentials without using the RPC authentication package.void xdr_callhdr(XDR *xdrs, struct rpc_msg *chdr); Used for describing RPC call header messages. This routine is useful for users who wish to generate RPC-style messages without using the RPC package.bool_t xdr_callmsg(XDR *xdrs, struct rpc_msg *cmsg); Used for describing RPC call messages. This routine is useful for users who wish to generate RPC-style messages without using the RPC package.bool_t xdr_opaque_auth(XDR *xdrs, struct opaque_auth *ap); Used for describing RPC authentication information messages. This routine is useful for users who wish to generate RPC-style messages without using the RPC package.bool_t xdr_pmap(XDR *xdrs, struct pmap *regs); Used for describing parameters to variousportmap procedures, externally. This routine is useful for users who wish to generate these parameters without using thepmapinterface.bool_t xdr_pmaplist(XDR *xdrs, struct pmaplist **rp); Used for describing a list of port mappings, externally. This routine is useful for users who wish to generate these parameters without using thepmapinterface.bool_t xdr_rejected_reply(XDR *xdrs, struct rejected_reply *rr); Used for describing RPC reply messages. This routine is useful for users who wish to generate RPC-style messages without using the RPC package.bool_t xdr_replymsg(XDR *xdrs, struct rpc_msg *rmsg); Used for describing RPC reply messages. This routine is useful for users who wish to generate RPC style messages without using the RPC package.void xprt_register(SVCXPRT *xprt); After RPC service transport handles are created, they should register themselves with the RPC service package. This routine modifies the global variablesvc_fds. Service implementors usually do not need this routine.void xprt_unregister(SVCXPRT *xprt); Before an RPC service transport handle is destroyed, it should unregister itself with the RPC service package. This routine modifies the global variablesvc_fds. Service implementors usually do not need this routine.
For an explanation of the terms used in this section, seeattributes(7). ┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface│Attribute│Value│ ├──────────────────────────────────────┼───────────────┼─────────┤ │auth_destroy(),authnone_create(), │ Thread safety │ MT-Safe │ │authunix_create(), │ │ │ │authunix_create_default(), │ │ │ │callrpc(),clnt_broadcast(), │ │ │ │clnt_call(),clnt_destroy(), │ │ │ │clnt_create(),clnt_control(), │ │ │ │clnt_freeres(),clnt_geterr(), │ │ │ │clnt_pcreateerror(),clnt_perrno(), │ │ │ │clnt_perror(),clnt_spcreateerror(), │ │ │ │clnt_sperrno(),clnt_sperror(), │ │ │ │clntraw_create(),clnttcp_create(), │ │ │ │clntudp_create(), │ │ │ │clntudp_bufcreate(), │ │ │ │get_myaddress(),pmap_getmaps(), │ │ │ │pmap_getport(),pmap_rmtcall(), │ │ │ │pmap_set(),pmap_unset(), │ │ │ │registerrpc(),svc_destroy(), │ │ │ │svc_freeargs(),svc_getargs(), │ │ │ │svc_getcaller(),svc_getreqset(), │ │ │ │svc_getreq(),svc_register(), │ │ │ │svc_run(),svc_sendreply(), │ │ │ │svc_unregister(),svcerr_auth(), │ │ │ │svcerr_decode(),svcerr_noproc(), │ │ │ │svcerr_noprog(),svcerr_progvers(), │ │ │ │svcerr_systemerr(), │ │ │ │svcerr_weakauth(),svcfd_create(), │ │ │ │svcraw_create(),svctcp_create(), │ │ │ │svcudp_bufcreate(),svcudp_create(), │ │ │ │xdr_accepted_reply(), │ │ │ │xdr_authunix_parms(),xdr_callhdr(), │ │ │ │xdr_callmsg(),xdr_opaque_auth(), │ │ │ │xdr_pmap(),xdr_pmaplist(), │ │ │ │xdr_rejected_reply(), │ │ │ │xdr_replymsg(),xprt_register(), │ │ │ │xprt_unregister() │ │ │ └──────────────────────────────────────┴───────────────┴─────────┘
xdr(3) The following manuals: Remote Procedure Calls: Protocol Specification Remote Procedure Call Programming Guide rpcgen Programming GuideRPC: Remote Procedure Call Protocol Specification, RFC 1050, Sun Microsystems, Inc., USC-ISI.
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