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rpc(3) Library Functions Manual rpc(3) NAME rpc, rpc_functions, auth_destroy, authnone_create, authunix_create, au- thunix_create_default, callrpc,clnt_broadcast, clnt_call, clnt_create, clnt_control, clnt_destroy, clnt_freeres, clnt_geterr, clnt_pcreateer- ror, clnt_perrno, clnt_perror, clnt_spcreateerror, clnt_sperrno, clnt_sperror, clntraw_create, clnttcp_create, clntudp_create, get_myad- dress, getnetname, host2netname, netname2host, netname2user, pmap_getmaps, pmap_getport, pmap_rmtcall, pmap_set, pmap_unset, regis- terrpc, rpc_createrr, svc_destroy, svc_fdset, svc_freeargs, svc_getargs, svc_getcaller, svc_getreq, svc_getreqset, 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_create, usr2netname, xprt_register, xprt_unregister - Library routines for ONC remote procedure calls SYNOPSIS #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 structures. The use of auth is undefined after calling auth_destroy(). 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 ONC RPC. AUTH * authunix_create(host, uid, gid, len, aup_gids) char *host; int uid, gid, len, *aup.gids; Creates and returns an ONC RPC authentication handle that con- tains authentication information. The host parameter 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 aup_gids refer to a counted array of groups to which the user belongs. AUTH * authunix_create_default() Calls authunix_create() with the appropriate parameters. callrpc(host, prognum, versnum, procnum, inproc, in, outproc, out) char *host; u_int 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 in parameter 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 re- sults. This routine returns zero if it succeeds, or the value of enum clnt_stat cast to an integer if it fails. The clnt_per- rno() routine is handy for translating failure statuses into messages. Warning: calling remote procedures with this routine uses UDP/IP as a transport; see clntudp_create() for restrictions. You do not have control of timeouts or authentication using this rou- tine. enum clnt_stat clnt_broadcast(prognum, versnum, procnum, inproc, in, outproc, out, eachresult) u_int prognum, versnum, procnum; char *in, *out; xdrproc_t inproc, outproc; resultproc_t eachresult; Like callrpc(), except the call message is broadcast to all lo- cally connected broadcast nets. Each time it receives a re- sponse, this routine calls the eachresult() routine, which has the following form: eachresult(out, addr) char *out; struct sockaddr_in *addr; The out parameter is the same as the out parameter passed to clnt_broadcast(), 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, clnt_broadcast() waits for more replies; otherwise it returns with appropriate status. If eachresult() is NULL clnt_broadcast() returns without waiting for any replies. Warning: broadcast sockets are limited in size to the maximum transfer unit of the data link. For Ethernet, the caller's argu- ment size should not exceed 1400 bytes. enum clnt_stat clnt_call(clnt, procnum, inproc, in, outproc, out, tout) CLIENT *clnt; u_int 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 routine such as clnt_create(). The in parameter 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 proce- dure'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 usu- ally involves deallocation of private data structures, including clnt itself. Use of clnt is undefined after calling clnt_de- stroy(). 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; u_int prog, vers; char *proto; Generic client creation routine. The host parameter identifies the name of the remote host where the server is located. The proto parameter 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 using clnt_control(). Warning: Since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for proce- dures that take large arguments or return huge results. bool_t clnt_control(cl, req, info) CLIENT *cl; int req; char *info; A macro that is used to change or retrieve various information about a client object. The req parameter indicates the type of operation, and info is a pointer to the information. For UDP and TCP, req has the following supported values, argument types, and purposes: tab(~); l l l. CLSET_TIMEOUT~struct timeval~set total timeout CLGET_TIMEOUT~struct timeval~get total timeout CLGET_FD~int~get associated socket CLSET_FD_CLOSE~void~T{ close socket on clnt_destroy() T} CLSET_FD_NOCLOSE~void~T{ leave socket open on clnt_destroy() T} Note: if you set the timeout using clnt_control(), the timeout parameter passed to clnt_call() will be ignored in all future calls. tab(~); l l l. CLGET_SERVER_ADDR~struct sockaddr~T{ get server's address T} The following operations are valid for UDP only: tab(~); l l l. CLSET_RETRY_TIMEOUT~struct timeval~T{ set the retry timeout T} CLGET_RETRY_TIMEOUT~struct timeval~T{ get the retry timeout T} 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 out parameter is the address of the results, and outproc is the XDR routine describ- ing the results. This routine returns one (1) if the results were successfully freed, and zero (0) 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. Used when a clnt_create(), clntraw_cre- ate(), clnttcp_create(), or clntudp_create() call fails. void clnt_perrno(stat) enum clnt_stat stat; Prints a message to standard error corresponding to the condi- tion indicated by stat. 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. Used after clnt_call(). char * clnt_spcreateerror char *s; Like clnt_pcreateerror(), except that it returns a string in- stead of printing to the standard error. Note: returns pointer to static data that is overwritten on each call. char * clnt_sperrno(stat) enum clnt_stat stat; Takes the same arguments as clnt_perrno(), but instead of send- ing a message to the standard error indicating why an RPC call failed, returns a pointer to a string which contains the mes- sage. The string ends with a NEWLINE. clnt_sperrno() is used instead of clnt_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 with printf, or if a message format differ- ent than that supported by clnt_perrno() is to be used. Note: unlike clnt_sperror() and clnt_spcreaterror(), clnt_sper- rno() does not return pointer to static data so the result will not be overwritten on each call. char * clnt_sperror(rpch, s) CLIENT *rpch; char *s; Like clnt_perror(), except that (like clnt_sperrno()) it returns a string instead of printing to standard error. Note: returns pointer to static data that is overwritten on each call. CLIENT * clntraw_create(prognum, versnum) u_int prognum, versnum; 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 corresponding RPC server should live in the same address space; see svcraw_create(). This 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. CLIENT * clnttcp_create(addr, prognum, versnum, sockp, sendsz, recvsz) struct sockaddr_in *addr; u_int prognum, versnum; int *sockp; u_int sendsz, recvsz; Creates an RPC client for the remote program prognum, version versnum; the client uses TCP/IP as a transport. The remote pro- gram is located at Internet address *addr. If addr->sin_port 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 RPC_ANYSOCK, then this routine opens a new socket 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 sendsz and recvsz parameters; values of zero choose suitable defaults. This routine returns NULL if it fails. CLIENT * clntudp_create(addr, prognum, versnum, wait, sockp) struct sockaddr_in *addr; u_int prognum, versnum; struct timeval wait; int *sockp; Creates an RPC client for the remote program prognum, version versnum; the client uses use UDP/IP as a transport. The remote program is located at Internet address addr. If addr->sin_port is zero, then it is set to 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 RPC_ANYSOCK, then this routine opens a new socket and sets sockp. The UDP transport resends the call message in intervals 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 clnt_call(). Warning: since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for proce- dures that take large arguments or return huge results. void get_myaddress(addr) struct sockaddr_in *addr; Places 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). getnetname(name) char name[MAXNETNAMELEN]; Installs the unique, operating-system independent network name of the caller in the fixed-length array name. Returns TRUE if it succeeds and FALSE if it fails. host2netname(name, host, domain) char *name; char *host; char *domain; Converts from a domain-specific host name to an operating-system independent network name. Return TRUE if it succeeds and FALSE if it fails. Inverse of netname2host(). netname2host(name, host, hostlen) char *name; char *host; int hostlen; Converts from an operating-system independent network name to a domain-specific host name. Returns TRUE if it succeeds and FALSE if it fails. Inverse of host2netname(). netname2user(name, uidp, gidp, gidlenp, gidlist) char *name; int *uidp; int *gidp; int *gidlenp; int *gidlist; Converts from an operating-system independent network name to a domain-specific user ID. Returns TRUE if it succeeds and FALSE if it fails. Inverse of user2netname(). 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 rpcinfo -p command uses this routine. u_short pmap_getport(addr, prognum, versnum, protocol) struct sockaddr_in *addr; u_int 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 versnum, and speaks the transport protocol as- sociated with protocol. The value of protocol is most likely IPPROTO_UDP or IPPROTO_TCP. A return value of zero means that the mapping does not exist or that the RPC system failed to con- tact the remote portmap service. In the latter case, the global variable rpc_createerr() contains the RPC status. enum clnt_stat pmap_rmtcall(addr, prognum, versnum, procnum, inproc, in, outproc, out, tout, portp) struct sockaddr_in *addr; u_int prognum, versnum, procnum; char *in, *out; xdrproc_t inproc, outproc; struct timeval tout; u_int *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 be- half to a procedure on that host. The *portp parameter will be modified to the program's port number if the procedure succeeds. The definitions of other parameters are discussed in callrpc() and clnt_call(). This procedure should be used for a "ping" and nothing else. See also clnt_broadcast(). pmap_set(prognum, versnum, protocol, port) u_int prognum, versnum, protocol; u_short 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 can be either IPPROTO_UDP or IPPROTO_TCP. This routine returns one (1) if it succeeds, zero (0) otherwise. Automatically done by svc_register(). pmap_unset(prognum, versnum) u_int prognum, versnum; A user interface to the portmap service, which destroys all map- ping between the triple [prognum,versnum,*] and ports on the ma- chine's portmap service. This routine returns one (1) if it suc- ceeds, zero (0) otherwise. registerrpc(prognum, versnum, procnum, procname, inproc, outproc) u_int prognum, versnum, procnum; char *(*procname) () ; xdrproc_t inproc, outproc; [Not Thread Safe] Registers procname procedure with the RPC service package. If a request arrives for prognum program, ver- snum version, and procnum procedure, 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 re- turns zero (0) if the registration succeeded, -1 otherwise. Warning: remote procedures registered in this form are accessed using the UDP/IP transport; see svcudp_create() for restric- tions. struct rpc_createerr rpc_createerr; A global variable whose value is set by any RPC client creation routine that does not succeed. Use the clnt_pcreateerror() rou- tine to print the reason for the error. svc_destroy(xprt) SVCXPRT * xprt; [Not Thread Safe] A macro that destroys the RPC service trans- port handle, xprt. Destruction 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 that reflects the RPC service side's read file descriptor bit mask; it is suitable as a arameter to the select system call. This is only of interest if a service implementor does not call svc_run(), but rather does his own asynchronous event processing. This variable is read-only (do not pass its address to select), yet it may change after calls to svc_getre- qset() or any creation routines. int svc_fds; Similar to svc_fdset(), but limited to 32 descriptors. This in- terface is obsoleted by svc_fdset(). svc_freeargs(xprt, inproc, in) SVCXPRT *xprt; xdrproc_t inproc; char *in; [Not Thread Safe] A macro that frees any data allocated by the RPC/XDR system when it decoded the arguments to a service proce- dure using svc_getargs(). This routine returns 1 if the results were successfully freed, and zero (0) otherwise. svc_getargs(xprt, inproc, in) SVCXPRT *xprt; xdrproc_t inproc; char *in; [Not Thread Safe] A macro that decodes the arguments of an RPC request associated with the RPC service transport handle, xprt. The in parameter is the address where the arguments will be placed; inproc is the XDR routine used to decode the arguments. This routine returns one (1) if decoding succeeds, and zero (0) otherwise. struct sockaddr_in * svc_getcaller(xprt) SVCXPRT *xprt; [Not Thread Safe] The approved way of getting the network ad- dress of the caller of a procedure associated with the RPC ser- vice transport handle, xprt. svc_getreq(rdfds) int rdfds; [Not Thread Safe] Similar to svc_getreqset(), but limited to 32 descriptors. This interface is obsoleted by svc_getreqset(). svc_getreqset(rdfds) fd_set *rdfds; [Not Thread Safe] This routine is only of interest if a service implementor does not call svc_run(), but instead implements cus- tom 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_register(xprt, prognum, versnum, dispatch, protocol) SVCXPRT *xprt; u_int prognum, versnum; void (*dispatch) (); int protocol; [Not Thread Safe] Associates prognum and versnum with the ser- vice 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->xp_port is established with the local portmap service (generally protocol is zero, IPPROTO_UDP or IPPROTO_TCP ). The dispatch procedure has the following form: dispatch(request, xprt) struct svc_req *request; SVCXPRT *xprt; The svc_register() routine returns one (1) if it succeeds, and zero (0) otherwise. svc_run() [Not Thread Safe] This routine waits for RPC requests to ar- rive, and calls the appropriate service procedure using svc_ge- treq() 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; [Not Thread Safe] Called by an RPC service's dispatch routine to send the results of a remote procedure call. The xprt para- meter 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 (1) if it succeeds, zero (0) otherwise. void svc_unregister(prognum, versnum) u_int prognum, versnum; [Not Thread Safe] Removes all mapping of the double [prognum,versnum] to dispatch routines, and of the triple [prognum,versnum,*] to port number. void svcerr_auth(xprt, why) SVCXPRT *xprt; enum auth_stat why; [Not Thread Safe] Called by a service dispatch routine that refuses to perform a remote procedure call due to an authentica- tion error. void svcerr_decode(xprt) SVCXPRT *xprt; [Not Thread Safe] Called by a service dispatch routine that cannot successfully decode its parameters. See also svc_getargs(). void svcerr_noproc(xprt) SVCXPRT *xprt; [Not Thread Safe] Called by a service dispatch routine that does not implement the procedure number that the caller re- quests. void svcerr_noprog(xprt) SVCXPRT *xprt; [Not Thread Safe] Called when the desired program is not regis- tered with the RPC package. Service implementors usually do not need this routine. void svcerr_progvers(xprt) SVCXPRT *xprt; [Not Thread Safe] 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; [Not Thread Safe] 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; [Not Thread Safe] Called by a service dispatch routine that re- fuses to perform a remote procedure call due to insufficient (but correct) authentication parameters. The routine calls svcerr_auth(xprt, AUTH_TOOWEAK). void svcfd_create(fd, sendsize, recvsize) int fd; u_int sendsize; u_int recvsize; [Not Thread Safe] Creates a service on top of any open descrip- tor. Typically, this descriptor is a connected socket for a stream protocol such as TCP. The sendsize and recvsize parame- ters indicate sizes for the send and receive buffers. If they are zero (0), a reasonable default is chosen. SVCXPRT * svcraw_create() [Not Thread Safe] 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; see clntraw_create(). This routine allows simulation of RPC and acquisition of RPC overheads (such as round trip times), without any kernel inter- ference. This routine returns NULL if it fails. SVCXPRT * svctcp_create(sock, send_buf_size, recv_buf_size) int sock; u_int send_buf_size, recv_buf_size; [Not Thread Safe] Creates a TCP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the sock socket, which may be RPC_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 com- pletion, xprt->xp_sock is the transport's socket descriptor, and xprt->xp_port is the transport's port number. This routine re- turns NULL if it fails. Since TCP-based RPC uses buffered I/O , users may specify the size of buffers; values of zero (0) choose suitable defaults. SVCXPRT * svcudp_create(sock) int sock; [Not Thread Safe] Creates a UDP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the sock socket, which may be RPC_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 com- pletion, xprt->xp_sock is the transport's socket descriptor, and xprt->xp_port is the transport's port number. This routine re- turns 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 proce- dures that take large arguments or return huge results. user2netname(name, uid, domain) char *name; int uid; char *domain; Converts from a domain-specific user name to an operating-system independent network name. Returns TRUE if it succeeds and FALSE if it fails. Inverse of netname2user(). void xprt_register(xprt) SVCXPRT *xprt; [Not Thread Safe] After RPC service transport handles are cre- ated, they should register themselves with the RPC service pack- age. This routine modifies the global variable svc_fds(). Ser- vice implementors usually do not need this routine. void xprt_unregister(xprt) SVCXPRT *xprt; [Not Thread Safe] Before an RPC service transport handle is de- stroyed, it should unregister itself with the RPC service pack- age. This routine modifies the global variable svc_fds(). Ser- vice implementors usually do not need this routine. DESCRIPTION These routines allow C programs to make procedure calls on other ma- chines 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. Unless otherwise indicated, the routines described in this reference page are thread safe (that is, they can be used safely in a multi- threaded environment). Routines that are not thread safe are flagged as such. RELATED INFORMATION xdr(3) Remote Procedure Calls: Protocol Specification-RFC 1050 delim off rpc(3)