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      1 /*	$NetBSD: net.c,v 1.36 2019/03/31 20:08:45 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992 Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. All advertising materials mentioning features or use of this software
     20  *    must display the following acknowledgement:
     21  *	This product includes software developed by the University of
     22  *	California, Lawrence Berkeley Laboratory and its contributors.
     23  * 4. Neither the name of the University nor the names of its contributors
     24  *    may be used to endorse or promote products derived from this software
     25  *    without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     37  * SUCH DAMAGE.
     38  *
     39  * @(#) Header: net.c,v 1.9 93/08/06 19:32:15 leres Exp  (LBL)
     40  */
     41 
     42 #include <sys/param.h>
     43 #include <sys/socket.h>
     44 
     45 #ifdef _STANDALONE
     46 #include <lib/libkern/libkern.h>
     47 #else
     48 #include <string.h>
     49 #endif
     50 
     51 #include <net/if.h>
     52 #include <net/if_ether.h>
     53 
     54 #include <netinet/in.h>
     55 #include <netinet/in_systm.h>
     56 #include <netinet/ip.h>
     57 
     58 #ifdef _STANDALONE
     59 #include "stand.h"
     60 #define delay()
     61 #else
     62 #include <errno.h>
     63 #include <stdio.h>
     64 #include <unistd.h>
     65 #define panic printf
     66 #define delay() usleep(100000)
     67 #endif
     68 
     69 #include "net.h"
     70 
     71 /*
     72  * Send a packet and wait for a reply, with exponential backoff.
     73  *
     74  * The send routine must return the actual number of bytes written,
     75  * or -1 on error.
     76  *
     77  * The receive routine can indicate success by returning the number of
     78  * bytes read; it can return 0 to indicate EOF; it can return -1 with a
     79  * non-zero errno to indicate failure; finally, it can return -1 with a
     80  * zero errno to indicate it isn't done yet.
     81  */
     82 ssize_t
     83 sendrecv(struct iodesc *d,
     84 	ssize_t (*sproc)(struct iodesc *, void *, size_t),
     85 	void *sbuf, size_t ssize,
     86 	ssize_t (*rproc)(struct iodesc *, void *, size_t, saseconds_t),
     87 	void *rbuf, size_t rsize)
     88 {
     89 	ssize_t cc;
     90 	satime_t t, tlast;
     91 	saseconds_t tmo, tleft;
     92 
     93 #ifdef NET_DEBUG
     94 	if (debug)
     95 		printf("%s: called\n", __func__);
     96 #endif
     97 
     98 	tmo = MINTMO;
     99 	tlast = 0;
    100 	tleft = 0;
    101 	t = getsecs();
    102 	for (;;) {
    103 		if (tleft <= 0) {
    104 			if (tmo >= MAXTMO) {
    105 				errno = ETIMEDOUT;
    106 				return -1;
    107 			}
    108 			cc = (*sproc)(d, sbuf, ssize);
    109 
    110 			tleft = tmo;
    111 			tmo <<= 1;
    112 			if (tmo > MAXTMO)
    113 				tmo = MAXTMO;
    114 
    115 			if (cc == -1) {
    116 				/* Error on transmit; wait before retrying */
    117 				while ((getsecs() - t) < tmo)
    118 					delay();
    119 				tleft = 0;
    120 				continue;
    121 			}
    122 			if ((size_t)cc < ssize)
    123 				panic("%s: short write! (%zd < %zu)", __func__,
    124 				    cc, ssize);
    125 
    126 			tlast = t;
    127 		}
    128 
    129 		/* Try to get a packet and process it. */
    130 		cc = (*rproc)(d, rbuf, rsize, tleft);
    131 		/* Return on data, EOF or real error. */
    132 		if (cc != -1 || errno != 0)
    133 			return cc;
    134 
    135 		/* Timed out or didn't get the packet we're waiting for */
    136 		t = getsecs();
    137 		tleft -= t - tlast;
    138 		tlast = t;
    139 	}
    140 }
    141