/*
 * clnt_udp.c, Implements a UDP/IP based, client side RPC.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 */

#include <stdio.h>
#include <rpc/rpc.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netdb.h>
#include <errno.h>
#include <rpc/pmap_clnt.h>
#include <cu.h>

/* program is the identifier of the service on the server */
/* A service can be implemented in different successive versions, version
   specifies which one you want to call */
   
struct cu_data *
ClntUdp_create(hostname, program, version)
	char *hostname;
	u_long program;
	u_long version;
{
	register int sockp;
	register struct cu_data *cu;
	struct rpc_msg call_msg;
	struct hostent *h;
	struct protoent *p;
	struct sockaddr_in sin;


            /* cu is the structure that stores all data related to the RPC */
            /* allocation of a buffer for sending and receiving data */
	sendsz = ((UDPMSGSIZE + 3) / 4) * 4;
	recvsz = ((UDPMSGSIZE + 3) / 4) * 4;
	cu = (struct cu_data *)mem_alloc(sizeof(*cu) + sendsz + recvsz);
	cu->cu_outbuf = &cu->cu_inbuf[recvsz];
	cu->cu_sendsz = sendsz;
	cu->cu_recvsz = recvsz;

            /* retrieve the IP address of the server, from its name */
        h = gethostbyname(hostname);
	sin.sin_family = h->h_addrtype;
	sin.sin_port = 0;
	bzero(sin.sin_zero, sizeof(sin.sin_zero));
	bcopy(h->h_addr, (char*)&sin.sin_addr, h->h_length);

	cu->cu_raddr = sin;
	cu->cu_rlen = sizeof (cu->cu_raddr);

            /* binding (client/server) id */
	call_msg.rm_xid = getpid();

            /* Constant header that is prepend to the procedure signature */
	call_msg.rm_direction = CALL;
	call_msg.rm_call.cb_rpcvers = RPC_MSG_VERSION;
	call_msg.rm_call.cb_prog = program;
	call_msg.rm_call.cb_vers = version;

            /* init of the structure cu_outxdrs which control encoding (decoding) */
            /* Encoding (Marshalling) result will be stored in the                */
            /* output buffer (cu->cu_outbuf)                                      */
	Xdrmem_create(&(cu->cu_outxdrs), cu->cu_outbuf,
	    sendsz, XDR_ENCODE);

            /* Encoding of the constant header */
            /* This is done once, then the result is reused for each subsequent rpc */
        Xdr_callhdr(&(cu->cu_outxdrs), &call_msg);

        cu->cu_xdrpos = XDR_GETPOS(&(cu->cu_outxdrs));

            /* socket initialization and server binding */
        sockp = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        (void)bindresvport(*sockp, (struct sockaddr_in *)0);

        cu->cu_sock = sockp;
        return cu;
}