431 lines
9.4 KiB
C
431 lines
9.4 KiB
C
/*-
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* Copyright (c) 1988 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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/*static char sccsid[] = "from: @(#)api_exch.c 4.2 (Berkeley) 4/26/91";*/
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static char rcsid[] = "$Id: api_exch.c,v 1.2 1993/08/01 18:06:21 mycroft Exp $";
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#endif /* not lint */
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#include <stdio.h>
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#include "../general/general.h"
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#include "api_exch.h"
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static int sock; /* Socket number */
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static char whoarewe[40] = "";
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#define WHO_ARE_WE() fprintf(stderr, "(API %s) ", whoarewe);
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static enum {CONTENTION, SEND, RECEIVE } conversation;
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static struct exch_exch exch_state;
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static unsigned int
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my_sequence,
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your_sequence;
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static char ibuffer[4000], *ibuf_next, *ibuf_last;
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#define IBUFADDED(i) ibuf_last += (i)
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#define IBUFAVAILABLE() (ibuf_last-ibuf_next)
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#define IBUFFER() ibuffer
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#define IBUFFREE() (ibuffer+sizeof ibuffer-ibuf_last-1)
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#define IBUFGETBYTES(w,l) { memcpy(w, ibuf_next, l); ibuf_next += l; }
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#define IBUFRESET() (ibuf_next = ibuf_last = ibuffer)
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char obuffer[4000], *obuf_next;
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#define OBUFADDBYTES(w,l) { memcpy(obuf_next, w, l); obuf_next += l; }
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#define OBUFAVAILABLE() (obuf_next - obuffer)
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#define OBUFFER() obuffer
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#define OBUFRESET() obuf_next = obuffer
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#define OBUFROOM() (obuffer+sizeof obuffer-obuf_next)
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static int
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outflush()
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{
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int length = OBUFAVAILABLE();
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if (length != 0) {
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if (write(sock, OBUFFER(), length) != length) {
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WHO_ARE_WE();
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perror("write");
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return -1;
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}
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OBUFRESET();
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}
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return 0; /* All OK */
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}
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static int
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iget(location, length)
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char *location;
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int length;
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{
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int count;
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if (OBUFAVAILABLE()) {
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if (outflush() == -1) {
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return -1;
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}
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}
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if ((count = IBUFAVAILABLE()) != 0) {
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if (count > length) {
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count = length;
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}
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IBUFGETBYTES(location, count);
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length -= count;
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location += count;
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}
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while (length) {
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if (ibuf_next == ibuf_last) {
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IBUFRESET();
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}
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if ((count = read(sock, IBUFFER(), IBUFFREE())) < 0) {
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WHO_ARE_WE();
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perror("read");
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return -1;
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}
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if (count == 0) {
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/* Reading past end-of-file */
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WHO_ARE_WE();
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fprintf(stderr, "End of file read\r\n");
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return -1;
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}
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IBUFADDED(count);
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if (count > length) {
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count = length;
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}
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IBUFGETBYTES(location, count);
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length -= count;
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location += count;
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}
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return 0;
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}
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static char *
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exch_to_ascii(exch)
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int exch; /* opcode to decode */
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{
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switch (exch) {
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case EXCH_EXCH_COMMAND:
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return "Command";
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case EXCH_EXCH_TYPE:
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return "Type";
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case EXCH_EXCH_TURNAROUND:
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return "Turnaround";
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case EXCH_EXCH_RTS:
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return "Request to Send";
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default:
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{
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static char unknown[40];
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sprintf(unknown, "(Unknown exchange 0x%02x)", exch&0xff);
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return unknown;
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}
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}
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}
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/*
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* Send the exch structure, updating the sequnce number field.
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*/
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static int
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send_state()
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{
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if (OBUFROOM() < sizeof exch_state) {
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if (outflush() == -1) {
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return -1;
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}
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}
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my_sequence = (my_sequence+1)&0xff;
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exch_state.my_sequence = my_sequence;
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exch_state.your_sequence = your_sequence;
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OBUFADDBYTES((char *)&exch_state, sizeof exch_state);
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return 0;
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}
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/*
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* Receive the exch structure from the other side, checking
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* sequence numbering.
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*/
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static int
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receive_state()
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{
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if (iget((char *)&exch_state, sizeof exch_state) == -1) {
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return -1;
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}
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if (conversation != CONTENTION) {
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if (exch_state.your_sequence != my_sequence) {
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WHO_ARE_WE();
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fprintf(stderr, "Send sequence number mismatch.\n");
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return -1;
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}
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if (exch_state.my_sequence != ((++your_sequence)&0xff)) {
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WHO_ARE_WE();
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fprintf(stderr, "Receive sequence number mismatch.\n");
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return -1;
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}
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}
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your_sequence = exch_state.my_sequence;
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return 0;
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}
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static int
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enter_receive()
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{
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switch (conversation) {
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case CONTENTION:
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exch_state.opcode = EXCH_EXCH_TURNAROUND;
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if (send_state() == -1) {
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return -1;
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}
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if (receive_state() == -1) {
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return -1;
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}
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if (exch_state.opcode != EXCH_EXCH_RTS) {
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WHO_ARE_WE();
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fprintf(stderr, "In CONTENTION state: ");
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if (exch_state.opcode == EXCH_EXCH_TURNAROUND) {
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fprintf(stderr,
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"Both sides tried to enter RECEIVE state.\n");
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} else {
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fprintf(stderr,
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"Protocol error trying to enter RECEIVE state.\n");
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}
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return -1;
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}
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break;
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case SEND:
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exch_state.opcode = EXCH_EXCH_TURNAROUND;
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if (send_state() == -1) {
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return -1;
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}
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break;
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}
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conversation = RECEIVE;
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return 0;
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}
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static int
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enter_send()
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{
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switch (conversation) {
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case CONTENTION:
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exch_state.opcode = EXCH_EXCH_RTS;
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if (send_state() == -1) {
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return -1;
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}
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/* fall through */
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case RECEIVE:
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if (receive_state() == -1) {
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return -1;
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}
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if (exch_state.opcode != EXCH_EXCH_TURNAROUND) {
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WHO_ARE_WE();
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fprintf(stderr, "Conversation error - both sides in SEND state.\n");
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return -1;
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}
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}
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conversation = SEND;
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return 0;
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}
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int
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api_exch_nextcommand()
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{
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if (conversation != RECEIVE) {
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if (enter_receive() == -1) {
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return -1;
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}
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}
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if (receive_state() == -1) {
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return -1;
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}
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if (exch_state.opcode != EXCH_EXCH_COMMAND) {
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WHO_ARE_WE();
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fprintf(stderr, "Expected a %s exchange, received a %s exchange.\n",
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exch_to_ascii(EXCH_EXCH_COMMAND), exch_to_ascii(exch_state.opcode));
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return -1;
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}
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return exch_state.command_or_type;
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}
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int
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api_exch_incommand(command)
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int command;
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{
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int i;
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if ((i = api_exch_nextcommand()) == -1) {
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return -1;
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}
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if (i != command) {
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WHO_ARE_WE();
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fprintf(stderr, "Expected API command 0x%x, got API command 0x%x.\n",
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command, i);
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return -1;
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}
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return 0;
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}
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int
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api_exch_outcommand(command)
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int command;
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{
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if (conversation != SEND) {
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if (enter_send() == -1) {
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return -1;
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}
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}
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exch_state.command_or_type = command;
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exch_state.opcode = EXCH_EXCH_COMMAND;
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if (send_state() == -1) {
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return -1;
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} else {
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return 0;
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}
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}
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int
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api_exch_outtype(type, length, location)
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int
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type,
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length;
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char
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*location;
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{
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int netleng = length;
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if (conversation != SEND) {
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if (enter_send() == -1) {
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return -1;
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}
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}
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exch_state.opcode = EXCH_EXCH_TYPE;
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exch_state.command_or_type = type;
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exch_state.length = netleng;
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if (send_state() == -1) {
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return -1;
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}
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if (length) {
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if (OBUFROOM() > length) {
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OBUFADDBYTES(location, length);
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} else {
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if (outflush() == -1) {
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return -1;
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}
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if (write(sock, location, length) != length) {
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WHO_ARE_WE();
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perror("write");
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return -1;
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}
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}
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}
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return 0;
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}
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int
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api_exch_intype(type, length, location)
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int
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type,
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length;
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char
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*location;
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{
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int netleng = length;
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if (conversation != RECEIVE) {
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if (enter_receive() == -1) {
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return -1;
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}
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}
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if (receive_state() == -1) {
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return -1;
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}
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if (exch_state.opcode != EXCH_EXCH_TYPE) {
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WHO_ARE_WE();
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fprintf(stderr,
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"Expected to receive a %s exchange, received a %s exchange.\n",
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exch_to_ascii(EXCH_EXCH_TYPE), exch_to_ascii(exch_state.opcode));
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return -1;
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}
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if (exch_state.command_or_type != type) {
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WHO_ARE_WE();
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fprintf(stderr, "Expected type 0x%x, got type 0x%x.\n",
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type, exch_state.command_or_type);
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return -1;
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}
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if (exch_state.length != netleng) {
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fprintf(stderr, "Type 0x%x - expected length %d, received length %u.\n",
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type, length, exch_state.length);
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return -1;
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}
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if (iget(location, length) == -1) {
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return -1;
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}
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return 0;
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}
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int
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api_exch_flush()
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{
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return outflush();
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}
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int
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api_exch_init(sock_number, ourname)
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int sock_number;
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char *ourname;
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{
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extern char *strcpy();
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sock = sock_number;
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(void) strcpy(whoarewe, ourname); /* For error messages */
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my_sequence = your_sequence = 0;
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conversation = CONTENTION; /* We don't know which direction */
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IBUFRESET();
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OBUFRESET();
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return 0;
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}
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