rpc(NS) 6 January 1993 rpc(NS) Name rpc - library routines for remote procedure calls Syntax and description 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. #include <rpc/rpc.h> void auth_destroy(auth) AUTH *auth; a macro that destroys the authentication information associated with auth. Destruction usually involves deallocation of private data struc- tures. The use of auth is undefined after calling authdestroy. AUTH * authnone_create() creates and returns 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(host, uid, gid, len, aup_gids) char *host; int uid, gid, len, *aup_gids; creates and returns an RPC authentication handle that contains authenti- cation information. The parameter host 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; len and aupgids refer to a counted array of groups to which the user belongs. AUTH * authunix_create_default() calls authunixcreate with the appropriate parameters callrpc(host, prognum, versnum, procnum, inproc, in, outproc, out) char *host; ulong prognum, versnum, procnum; char *in, *out; xdrproc_t inproc, outproc; calls the remote procedure associated with prognum, versnum, and procnum on the machine, host. The parameter in is the address of the procedure's argument(s) and out is the address of where to place the result(s); inproc is used to encode the procedure's parameters and outproc is used to decode the procedure's results. This routine returns zero if it succeeds; if it fails, it returns the value of enum clntstat cast to an integer. The routine clntperrno is useful for translating failure status data into messages. _________________________________________________________________________ WARNING Calling remote procedures with this routine uses UDP/IP as a transport; see clntudpcreate for restrictions. You do not have control of timeouts or authentication when using this routine. _________________________________________________________________________ enum clnt_stat clnt_broadcast(prognum, versnum, procnum, inproc, in, outproc, out, eachresult) ulong prognum, versnum, procnum; char *in, *out; xdrproc_t inproc, outproc; resultproc_t eachresult; like callrpc, except the call message is broadcast to all locally con- nected broadcast nets. Each time it receives a response, this routine calls eachresult, whose form is: eachresult(out, addr) char *out; struct sockaddr_in *addr; where out is the same as out passed to clntbroadcast, except that the remote procedure's output is decoded there; addr points to the address of the machine that sent the results. If eachresult returns zero, clntbroadcast 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(clnt, procnum, inproc, in, outproc, out, tout) CLIENT *clnt; ulong procnum; xdrproc_t inproc, outproc; char *in, *out; struct timeval tout; a macro that calls the remote procedure procnum associated with the client handle, clnt, which is obtained with an RPC client creation rou- tine such as clntcreate. The parameter in is the address of the procedure's argument(s) and out is the address of where to place the result(s); inproc is used to encode the procedure's parameters and outproc is used to decode the procedure's results; tout is the time allowed for results to come back. clnt_destroy(clnt) CLIENT *clnt; a macro that destroys the client's RPC handle. Destruction usually involves deallocation of private data structures, including clnt itself. Use of clnt is undefined after calling clntdestroy. If the RPC library opened the associated socket, it will close it also. Otherwise, the socket remains open. CLIENT * clnt_create (host, prog, vers, proto) char *host; ulong prog, vers; char *proto; generic client creation routine. host identifies the name of the remote host where the server is located. proto indicates which kind of trans- port protocol to use. The currently supported values for this field are udp and tcp. Default timeouts are set, but can be modified using clntcontrol. _________________________________________________________________________ WARNING Using UDP has its shortcomings. Since UDP-based RPC mes- sages can only hold 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(cl, req, info) CLIENT *cl; char *info; a macro used to change or retrieve various information about a client object. req indicates the type of operation and info is a pointer to the information. For both UDP and TCP, the supported values of req and their argument types and what they do are: CLSETTIMEOUT struct timeval set total timeout CLGETTIMEOUT struct timeval get total timeout _________________________________________________________________________ NOTE If you set the timeout using clntcontrol, the timeout param- eter passed to clntcall will be ignored in all future calls. _________________________________________________________________________ CLGETSERVERADDR struct sockaddr get server's address The following operations are valid for UDP only: CLSETRETRYTIMEOUT struct timeval set the retry timeout CLGETRETRYTIMEOUT struct 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(clnt, outproc, out) CLIENT *clnt; xdrproc_t outproc; char *out; a macro that frees any data allocated by the RPC/XDR system when it decoded the results of an RPC call. The parameter out is the address of the results and outproc is the XDR routine describing the results in sim- ple primitives. This routine returns one if the results were success- fully freed; zero otherwise. void clnt_geterr(clnt, errp) CLIENT *clnt; struct rpc_err *errp; a macro that copies the error structure out of the client handle to the structure at address errp void clnt_pcreateerror(s) char *s; prints a message to standard error indicating why a client RPC handle could not be created. The message is prepended with string s and a colon. This is used when a clntcreate, clntrawcreate, clnttcpcreate, or clntudpcreate call fails. void clnt_perrno(stat) enum clnt_stat stat; prints a message to standard error corresponding to the condition indi- cated by stat. This is used after callrpc. clnt_perror(clnt, s) CLIENT *clnt; char *s; prints 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 string s and a colon. This is used after clntcall. char * clnt_spcreateerror(s) char *s; like clntpcreateerror, except that it returns a string instead of print- ing to the standard error BUGS: returns pointer to static data that is overwritten on each call char * clnt_sperrno(stat) enum clnt_stat stat; takes the same arguments as clntperrno, but instead of sending a message to the standard error to indicate why an RPC call failed, it returns a pointer to a string which contains the message. The string ends with a newline. clntsperrno is used instead of clntperrno 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 with printf, or if a message format different than that supported by clntperrno is to be used. _________________________________________________________________________ NOTE Unlike clntsperror and clntspcreaterror, clntsperrno does not return pointer to static data, so the result will not get overwritten on each call. _________________________________________________________________________ char * clnt_sperror(rpch, s) CLIENT *rpch; char *s; like clntperror, except that (like clntsperrno) 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(prognum, versnum) ulong prognum, versnum; This routine creates a toy RPC client for the remote program prognum, version versnum. The transport used to pass messages to the service is actually a buffer within the process's address space, so the corre- sponding RPC server should live in the same address space; see svcrawcreate. 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(addr, prognum, versnum, sockp, sendsz, recvsz) struct sockaddr_in *addr; ulong prognum, versnum; int *sockp; uint sendsz, recvsz; This routine creates an RPC client for the remote program prognum, ver- sion versnum; the client uses TCP/IP as a transport. The remote program is located at Internet address *addr. If addr->sinport is zero, then it is set to the actual port that the remote program is listening on (the remote portmap service is consulted for this information). The parameter sockp is a socket; if it is RPCANYSOCK, then this routine opens a new one and sets sockp. Since TCP-based RPC uses buffered I/O, the user may specify the size of the send and receive buffers with the parameters sendsz and recvsz; zero values of these parameters choose suitable defaults. This routine returns NULL if it fails. CLIENT * clntudp_create(addr, pronum, versnum, wait, sockp) struct sockaddr_in *addr; ulong prognum, versnum; struct timeval wait; int *sockp; This routine creates an RPC client for the remote program prognum, ver- sion versnum; the client uses UDP/IP as a transport. The remote program is located at Internet address addr. If addr->sinport is zero, then it is set to the actual port that the remote program is listening on (the remote portmap service is consulted for this information). The parameter sockp is a socket; if it is RPCANYSOCK, then this routine opens a new one and sets sockp. The UDP transport resends the call message in inter- vals of wait time until a response is received or until the call times out. The total time for the call to time out is specified by clntcall. _________________________________________________________________________ WARNING Since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results. _________________________________________________________________________ void get_myaddress(addr) struct sockaddr_in *addr; stuffs the machine's IP address into *addr, without consulting the library routines that deal with /etc/hosts. The port number is always set to htons(PMAPPORT). struct pmaplist * pmap_getmaps(addr) struct sockaddr_in *addr; a user interface to the portmap service, 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 command rpcinfo -p uses this routine. ushort pmap_getport(addr, prognum, versnum, protocol) struct sockaddr_in *addr; ulong prognum, versnum, protocol; a user interface to the portmap service, which returns the port number on which waits a service that supports program number prognum, version vers- num, and speaks the transport protocol associated with protocol. The value of protocol is most likely IPPROTOUDP or IPPROTOTCP. A return value of zero means that the mapping does not exist or that the RPC sys- tem failed to contact the remote portmap service. In the latter case, the global variable rpccreateerr contains the RPC status. enum clnt_stat pmap_rmtcall(addr, prognum, versnum, procnum, inproc, in, outproc, out, tout, portp) struct sockaddr_in *addr; ulong prognum, versnum, procnum; char *in, *out; xdrproc_t inproc, outproc; struct timeval tout; ulong *portp; a user interface to the portmap service which instructs portmap on the host at IP address *addr to make an RPC call on your behalf to a pro- cedure 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 in callrpc and clntcall. This procedure should be used for a ``ping'' only and nothing else. See also clntbroadcast. pmap_set(prognum, versnum, protocol, port) ulong prognum, versnum, protocol; ushort port; a user interface to the portmap service, which establishes a mapping between the triple (prognum,versnum,protocol) and port on the machine's portmap service. The value of protocol is most likely IPPROTOUDP or IPPROTOTCP. This routine returns one if it succeeds; zero otherwise. This is done automatically by svcregister. pmap_unset(prognum, versnum) ulong prognum, versnum; a user interface to the portmap service which destroys all mapping between the triple [prognum, versnum, *] and ports on the machine's port- map service. This routine returns one if it succeeds; zero otherwise. registerrpc(prognum, versnum, procnum, procname, inproc, outproc) ulong prognum, versnum, procnum; char *(*procname) () ; xdrproc_t inproc, outproc; registers procedure procname with the RPC service package. If a request arrives for program prognum, version versnum, and procedure procnum, procname is called with a pointer to its parameter(s); progname should return a pointer to its static result(s); inproc is used to decode the parameters while outproc 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; see svcudpcreate for restrictions. _________________________________________________________________________ struct rpc_createerr rpc_createerr; a global variable whose value is set by any RPC client creation routine that does not succeed. Use the routine clntpcreateerror to print the reason why. svc_destroy(xprt) SVCXPRT * xprt; a macro that destroys the RPC service transport handle, xprt. Destruc- tion usually involves deallocation of private data structures, including xprt itself. Use of xprt is undefined after calling this routine. fd_set svc_fdset; a global variable reflecting the RPC service side's read file descriptor bit mask; it is suitable as a parameter to the select system call. This is needed only if a service implementor does not call svcrun, but rather does his own asynchronous event processing. This variable is read-only (do not pass its address to select), but it may change after calls to svcgetreqset or any creation routines. int svc_fds; similar to svcfedset, but limited to 32 descriptors. svcfdset makes this interface obsolete. svc_freeargs(xprt, inproc, in) SVCXPRT *xprt; xdrproc_t inproc; char *in; a macro that frees any data allocated by the RPC/XDR system when it decoded the arguments to a service procedure using svcgetargs. This routine returns one if the results were successfully freed; zero other- wise. svc_getargs(xprt, inproc, in) SVCXPRT *xprt; xdrproc_t inproc; char *in; a macro that decodes the arguments of an RPC request associated with the RPC service transport handle, xprt. The parameter in 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; zero otherwise. struct sockaddr_in * svc_getcaller(xprt) SVCXPRT *xprt; the approved way of getting the network address of the caller of a pro- cedure associated with the RPC service transport handle, xprt. svc_getreqset(rdfds) fd_set *rdfds; This routine is needed only if a service implementor does not call svcrun, but instead implements custom asynchronous event-processing. It is called when the select 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 of rdfds have been serviced. svc_getreq(rdfds) int rdfds; similar to svcgetreqset, but limited to 32 descriptors. This interface is made obsolete by svcgetreqset. svc_register(xprt, prognum, versnum, dispatch, protocol) SVCXPRT *xprt; ulong prognum, versnum; void (*dispatch) (); ulong protocol; associates prognum and versnum with the service dispatch procedure, dispatch. If protocol is zero, the service is not registered with the portmap service. If protocol is non-zero, then a mapping of the triple (prognum, versnum, protocol) to xprt->xpport is established with the local portmap service (generally protocol is zero, IPPROTOUDP or IPPROTOTCP). The procedure dispatch has the following form: dispatch(request, xprt) struct svc_req *request; SVCXPRT *xprt; The svcregister routine returns one if it succeeds; zero otherwise. svc_run() This routine never returns. It waits for RPC requests to arrive and calls the appropriate service procedure using svcgetreq when one arrives. This procedure is usually waiting for a select system call to return. svc_sendreply(xprt, outproc, out) SVCXPRT *xprt; xdrproc_t outproc; char *out; called by an RPC service's dispatch routine to send the results of a remote procedure call. The parameter, xprt, is the request's associated transport handle; outproc is the XDR routine which is used to encode the results, and out is the address of the results. This routine returns one if it succeeds; zero otherwise. void svc_unregister(prognum, versnum) ulong prognum, versnum; removes all mapping of the double (prognum, versnum) to the dispatch rou- tines and of the triple (prognum, versnum, *) to the port number. void svcerr_auth(xprt, why) SVCXPRT *xprt; enum auth_stat why; called by a service dispatch routine that refuses to perform a remote procedure call due to an authentication error. void svcerr_decode(xprt) SVCXPRT *xprt; called by a service dispatch routine that cannot decode its parameters successfully. See also svcgetargs. void svcerr_noproc(xprt) SVCXPRT *xprt; called by a service dispatch routine that does not implement the pro- cedure number that the caller requests. void svcerr_noprog(xprt) 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(xprt) SVCXPRT *xprt; 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(xprt) 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(xprt) SVCXPRT *xprt; called by a service dispatch routine that refuses to perform a remote procedure call due to insufficient (but correct) authentication parame- ters. The routine calls svcerrauth(xprt, AUTHTOOWEAK). SVCXPRT * svcraw_create() This routine creates a toy RPC service transport and returns a pointer to it. The transport is really a buffer within the process's address space, so the corresponding RPC client should live in the same address space; see clntrawcreate. This routine allows simulation of RPC and acquisi- tion of RPC overheads (such as round trip times) without any kernel interference. This routine returns NULL if it fails. SVCXPRT * svctcp_create(sock, send_buf_size, recv_buf_size) int sock; uint send_buf_size, recv_buf_size; This routine creates a TCP/IP-based RPC service transport and returns a pointer to it. The transport is associated with the socket sock, which may be RPCANYSOCK, 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 arbi- trary port. Upon completion, xprt->xpsock is the transport's socket number and xprt->xpport 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; zero values for these parameters choose suitable defaults. void svcfd_create(fd, sendsize, recvsize) int fd; uint sendsize; uint recvsize; creates a service on top of any open descriptor. Typically, this descriptor is a connected socket for a stream protocol such as TCP. sendsize and recvsize indicate sizes for the send and receive buffers. If they are zero, reasonable defaults are chosen. SVCXPRT * svcudp_create(sock) int sock; This routine creates a UDP/IP-based RPC service transport and returns a pointer to it. The transport is associated with the socket, sock, which may be RPCANYSOCK, 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 arbi- trary port. Upon completion, xprt->xpsock is the transport's socket number and xprt->xpport is the transport's port number. This routine returns NULL if it fails. _________________________________________________________________________ WARNING Since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results. _________________________________________________________________________ xdr_accepted_reply(xdrs, ar) XDR *xdrs; struct accepted_reply *ar; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC-style messages without using the RPC pack- age. xdr_authunix_parms(xdrs, aupp) XDR *xdrs; struct authunix_parms *aupp; used for describing UNIX credentials externally. This routine is useful for users who wish to generate these credentials without using the RPC authentication package. void xdr_callhdr(xdrs, chdr) XDR *xdrs; struct rpc_msg *chdr; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC-style messages without using the RPC pack- age. xdr_callmsg(xdrs, cmsg) XDR *xdrs; struct rpc_msg *cmsg; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC-style messages without using the RPC pack- age. xdr_opaque_auth(xdrs, ap) XDR *xdrs; struct opaque_auth *ap; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC-style messages without using the RPC package. xdr_pmap(xdrs, regs) XDR *xdrs; struct pmap *regs; used for describing parameters to various portmap procedures externally. This routine is useful for users who wish to generate these parameters without using the pmap interface. xdr_pmaplist(xdrs, rp) 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 the pmap interface. xdr_rejected_reply(xdrs, rr) XDR *xdrs; struct rejected_reply *rr; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC-style messages without using the RPC pack- age. xdr_replymsg(xdrs, rmsg) XDR *xdrs; struct rpc_msg *rmsg; used for describing RPC messages externally. This routine is useful for users who wish to generate RPC style messages without using the RPC pack- age. void xprt_register(xprt) SVCXPRT *xprt; After RPC service transport handles are created, they should register themselves with the RPC service package. This routine modifies the glo- bal variable svcfds. Service implementors usually do not need this rou- tine. void xprt_unregister(xprt) SVCXPRT *xprt; Before an RPC service transport handle is destroyed, it should unregister itself with the RPC service package. This routine modifies the global variable, svcfds. Service implementors usually do not need this rou- tine. See also xdr(NS)