rfscomm.c File Reference

#include <xinu.h>

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Functions
int32	rfscomm (struct rf_msg_hdr *msg, int32 mlen, struct rf_msg_hdr *reply, int32 rlen)

Function Documentation

rfscomm()

int32 rfscomm	(	struct rf_msg_hdr *	msg,
		int32	mlen,
		struct rf_msg_hdr *	reply,
		int32	rlen
	)

Definition at line 10 of file rfscomm.c.

References htonl, kprintf(), ntohl, ntohs, Rf_data, rfdata::rf_loc_port, RF_MSG_RESPONSE, rfdata::rf_registered, RF_RETRIES, rfdata::rf_seq, rfdata::rf_ser_ip, rfdata::rf_ser_port, RF_TIMEOUT, rfdata::rf_udp_slot, SYSERR, TIMEOUT, TRUE, udp_recv(), udp_register(), and udp_send().

Referenced by rflread(), rflwrite(), rfscontrol(), rfsndmsg(), and rfsopen().

{
    int32   i;          /* Counts retries       */
    int32   retval;         /* Return value         */
    int32   seq;            /* Sequence for this exchange   */
    int16   rtype;          /* Reply type in host byte order*/
    int32   slot;           /* UDP slot         */

    /* For the first time after reboot, register the server port */

    if ( ! Rf_data.rf_registered ) {
        if ( (slot = udp_register(Rf_data.rf_ser_ip,
                Rf_data.rf_ser_port,
                Rf_data.rf_loc_port)) == SYSERR) {
            return SYSERR;
        }
        Rf_data.rf_udp_slot = slot;
        Rf_data.rf_registered = TRUE;
    }

    /* Assign message next sequence number */

    seq = Rf_data.rf_seq++;
    msg->rf_seq = htonl(seq);

    /* Repeat RF_RETRIES times: send message and receive reply */

    for (i=0; i<RF_RETRIES; i++) {

        /* Send a copy of the message */

        retval = udp_send(Rf_data.rf_udp_slot, (char *)msg,
            mlen);
        if (retval == SYSERR) {
            kprintf("Cannot send to remote file server\n");
            return SYSERR;
        }

        /* Receive a reply */

        retval = udp_recv(Rf_data.rf_udp_slot, (char *)reply,
            rlen, RF_TIMEOUT);

        if (retval == TIMEOUT) {
            continue;
        } else if (retval == SYSERR) {
            kprintf("Error reading remote file reply\n");
            return SYSERR;
        }

        /* Verify that sequence in reply matches request */

        if (ntohl(reply->rf_seq) != seq) {
            continue;
        }

        /* Verify the type in the reply matches the request */

        rtype = ntohs(reply->rf_type);
        if (rtype != ( ntohs(msg->rf_type) | RF_MSG_RESPONSE) ) {
            continue;
        }

        return retval;      /* Return length to caller */
    }

    /* Retries exhausted without success */

    kprintf("Timeout on exchange with remote file server\n");
    return TIMEOUT;
}

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