RPC_CLNT_CREATE

Section: C Library Functions (3)
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NAME

rpc_clnt_create clnt_control clnt_create clnt_create_timed clnt_create_vers clnt_create_vers_timed clnt_destroy clnt_dg_create clnt_pcreateerror clnt_raw_create clnt_spcreateerror clnt_tli_create clnt_tp_create clnt_tp_create_timed clnt_vc_create rpc_createerr - library routines for dealing with creation and manipulation of Vt CLIENT handles

SYNOPSIS

In rpc/rpc.h Ft bool_t Fn clnt_control CLIENT *clnt const u_int req char *info Ft CLIENT * Fn clnt_create const char * host const rpcprog_t prognum const rpcvers_t versnum const char *nettype Ft CLIENT * Fn clnt_create_timed const char * host const rpcprog_t prognum const rpcvers_t versnum const char *nettype const struct timeval *timeout Ft CLIENT * Fn clnt_create_vers const char * host const rpcprog_t prognum rpcvers_t *vers_outp const rpcvers_t vers_low const rpcvers_t vers_high const char *nettype Ft CLIENT * Fn clnt_create_vers_timed const char * host const rpcprog_t prognum rpcvers_t *vers_outp const rpcvers_t vers_low const rpcvers_t vers_high char *nettype const struct timeval *timeout Ft void Fn clnt_destroy CLIENT *clnt Ft CLIENT * Fn clnt_dg_create const int fildes const struct netbuf *svcaddr const rpcprog_t prognum const rpcvers_t versnum const u_int sendsz const u_int recvsz Ft void Fn clnt_pcreateerror const char *s Ft char * Fn clnt_spcreateerror const char *s Ft CLIENT * Fn clnt_raw_create const rpcprog_t prognum const rpcvers_t versnum Ft CLIENT * Fn clnt_tli_create const int fildes const struct netconfig *netconf const struct netbuf *svcaddr const rpcprog_t prognum const rpcvers_t versnum const u_int sendsz const u_int recvsz Ft CLIENT * Fn clnt_tp_create const char * host const rpcprog_t prognum const rpcvers_t versnum const struct netconfig *netconf Ft CLIENT * Fn clnt_tp_create_timed const char * host const rpcprog_t prognum const rpcvers_t versnum const struct netconfig *netconf const struct timeval *timeout Ft CLIENT * Fn clnt_vc_create const int fildes const struct netbuf *svcaddr const rpcprog_t prognum const rpcvers_t versnum u_int sendsz u_int recvsz

DESCRIPTION

RPC library routines allow C language programs to make procedure calls on other machines across the network. First a Vt CLIENT handle is created and then the client calls a procedure to send a request to the server. On receipt of the request, the server calls a dispatch routine to perform the requested service, and then sends a reply.

Routines

Fn clnt_control

A function macro to change or retrieve various information about a client object. The Fa req argument indicates the type of operation, and Fa info is a pointer to the information. For both connectionless and connection-oriented transports, the supported values of Fa req and their argument types and what they do are:

CLSET_TIMEOUT Ta struct timeval * Ta set total timeout
CLGET_TIMEOUT Ta struct timeval * Ta get total timeout

Note: if you set the timeout using Fn clnt_control , the timeout argument passed by Fn clnt_call is ignored in all subsequent calls.

Note: If you set the timeout value to 0, Fn clnt_control immediately returns an error (RPC_TIMEDOUT ) Set the timeout argument to 0 for batching calls.

CLGET_SVC_ADDR Ta struct netbuf * Ta get servers address
CLGET_FD Ta int * Ta get fd from handle
CLSET_FD_CLOSE Ta void Ta close fd on destroy
CLSET_FD_NCLOSE Ta void Ta don't close fd on destroy
CLGET_VERS Ta u_int32_t * Ta get RPC program version
CLSET_VERS Ta u_int32_t * Ta set RPC program version
CLGET_XID Ta u_int32_t * Ta get XID of previous call
CLSET_XID Ta u_int32_t * Ta set XID of next call

The following operations are valid for connectionless transports only:

CLSET_RETRY_TIMEOUT Ta struct timeval * Ta set the retry timeout
CLGET_RETRY_TIMEOUT Ta struct timeval * Ta get the retry timeout
CLSET_CONNECT Ta Vt int * Ta use connect(2)

The retry timeout is the time that RPC waits for the server to reply before retransmitting the request. The Fn clnt_control function returns TRUE on success and FALSE on failure.

Fn clnt_create

Generic client creation routine for program Fa prognum and version Fa versnum . The Fa host argument identifies the name of the remote host where the server is located. The Fa nettype argument indicates the class of transport protocol to use. The transports are tried in left to right order in NETPATH environment variable or in top to bottom order in the netconfig database. The Fn clnt_create function tries all the transports of the Fa nettype class available from the NETPATH environment variable and the netconfig database, and chooses the first successful one. A default timeout is set and can be modified using Fn clnt_control . This routine returns NULL if it fails. The Fn clnt_pcreateerror routine can be used to print the reason for failure.

Note: Fn clnt_create returns a valid client handle even if the particular version number supplied to Fn clnt_create is not registered with the rpcbind(8) service. This mismatch will be discovered by a Fn clnt_call later (see rpc_clnt_calls3).

Fn clnt_create_timed

Generic client creation routine which is similar to Fn clnt_create but which also has the additional argument Fa timeout that specifies the maximum amount of time allowed for each transport class tried. In all other respects, the Fn clnt_create_timed call behaves exactly like the Fn clnt_create call.

Fn clnt_create_vers

Generic client creation routine which is similar to Fn clnt_create but which also checks for the version availability. The Fa host argument identifies the name of the remote host where the server is located. The Fa nettype argument indicates the class transport protocols to be used. If the routine is successful it returns a client handle created for the highest version between Fa vers_low and Fa vers_high that is supported by the server. The Fa vers_outp argument is set to this value. That is, after a successful return Fa vers_low <= Fa *vers_outp <= Fa vers_high . If no version between Fa vers_low and Fa vers_high is supported by the server then the routine fails and returns NULL A default timeout is set and can be modified using Fn clnt_control . This routine returns NULL if it fails. The Fn clnt_pcreateerror routine can be used to print the reason for failure. Note: Fn clnt_create returns a valid client handle even if the particular version number supplied to Fn clnt_create is not registered with the rpcbind(8) service. This mismatch will be discovered by a Fn clnt_call later (see rpc_clnt_calls3). However, Fn clnt_create_vers does this for you and returns a valid handle only if a version within the range supplied is supported by the server.

Fn clnt_create_vers_timed

Generic client creation routine which is similar to Fn clnt_create_vers but which also has the additional argument Fa timeout that specifies the maximum amount of time allowed for each transport class tried. In all other respects, the Fn clnt_create_vers_timed call behaves exactly like the Fn clnt_create_vers call.

Fn clnt_destroy

A function macro that destroys the client's RPC handle. Destruction usually involves deallocation of private data structures, including Fa clnt itself. Use of Fa clnt is undefined after calling Fn clnt_destroy . If the RPC library opened the associated file descriptor, or CLSET_FD_CLOSE was set using Fn clnt_control , the file descriptor will be closed. The caller should call Fn auth_destroy clnt->cl_auth (before calling Fn clnt_destroy ) to destroy the associated Vt AUTH structure (see rpc_clnt_auth3).

Fn clnt_dg_create

This routine creates an RPC client for the remote program Fa prognum and version Fa versnum ; the client uses a connectionless transport. The remote program is located at address Fa svcaddr . The Fa fildes argument is an open and bound file descriptor. This routine will resend the call message in intervals of 15 seconds until a response is received or until the call times out. The total time for the call to time out is specified by Fn clnt_call (see Fn clnt_call in rpc_clnt_calls3). The retry time out and the total time out periods can be changed using Fn clnt_control . The user may set the size of the send and receive buffers with the Fa sendsz and Fa recvsz arguments; values of 0 choose suitable defaults. This routine returns NULL if it fails.

Fn clnt_pcreateerror

Print a message to standard error indicating why a client RPC handle could not be created. The message is prepended with the string Fa s and a colon, and appended with a newline.

Fn clnt_spcreateerror

Like Fn clnt_pcreateerror , except that it returns a string instead of printing to the standard error. A newline is not appended to the message in this case. Warning: returns a pointer to a buffer that is overwritten on each call.

Fn clnt_raw_create

This routine creates an RPC client handle for the remote program Fa prognum and version Fa versnum . The transport used to pass messages to the service is a buffer within the process's address space, so the corresponding RPC server should live in the same address space; (see Fn svc_raw_create in rpc_svc_create3). This allows simulation of RPC and measurement of RPC overheads, such as round trip times, without any kernel or networking interference. This routine returns NULL if it fails. The Fn clnt_raw_create function should be called after Fn svc_raw_create .

Fn clnt_tli_create

This routine creates an RPC client handle for the remote program Fa prognum and version Fa versnum . The remote program is located at address Fa svcaddr . If Fa svcaddr is NULL and it is connection-oriented, it is assumed that the file descriptor is connected. For connectionless transports, if Fa svcaddr is NULL RPC_UNKNOWNADDR error is set. The Fa fildes argument is a file descriptor which may be open, bound and connected. If it is RPC_ANYFD it opens a file descriptor on the transport specified by Fa netconf . If Fa fildes is RPC_ANYFD and Fa netconf is NULL a RPC_UNKNOWNPROTO error is set. If Fa fildes is unbound, then it will attempt to bind the descriptor. The user may specify the size of the buffers with the Fa sendsz and Fa recvsz arguments; values of 0 choose suitable defaults. Depending upon the type of the transport (connection-oriented or connectionless), Fn clnt_tli_create calls appropriate client creation routines. This routine returns NULL if it fails. The Fn clnt_pcreateerror routine can be used to print the reason for failure. The remote rpcbind service (see rpcbind(8)) is not consulted for the address of the remote service.

Fn clnt_tp_create

Like Fn clnt_create except Fn clnt_tp_create tries only one transport specified through Fa netconf . The Fn clnt_tp_create function creates a client handle for the program Fa prognum , the version Fa versnum , and for the transport specified by Fa netconf . Default options are set, which can be changed using Fn clnt_control calls. The remote rpcbind service on the host Fa host is consulted for the address of the remote service. This routine returns NULL if it fails. The Fn clnt_pcreateerror routine can be used to print the reason for failure.

Fn clnt_tp_create_timed

Like Fn clnt_tp_create except Fn clnt_tp_create_timed has the extra argument Fa timeout which specifies the maximum time allowed for the creation attempt to succeed. In all other respects, the Fn clnt_tp_create_timed call behaves exactly like the Fn clnt_tp_create call.

Fn clnt_vc_create

This routine creates an RPC client for the remote program Fa prognum and version Fa versnum ; the client uses a connection-oriented transport. The remote program is located at address Fa svcaddr . The Fa fildes argument is an open and bound file descriptor. The user may specify the size of the send and receive buffers with the Fa sendsz and Fa recvsz arguments; values of 0 choose suitable defaults. This routine returns NULL if it fails. The address Fa svcaddr should not be NULL and should point to the actual address of the remote program. The Fn clnt_vc_create function does not consult the remote rpcbind service for this information.

Vt struct rpc_createerr Va rpc_createerr ;

A global variable whose value is set by any RPC client handle creation routine that fails. It is used by the routine Fn clnt_pcreateerror to print the reason for the failure.

AVAILABILITY

These functions are part of libtirpc.