4.3BSD-Reno/src/usr.bin/tftp/tftpsubs.c
/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that: (1) source distributions retain this entire copyright
* notice and comment, and (2) distributions including binaries display
* the following acknowledgement: ``This product includes software
* developed by the University of California, Berkeley and its contributors''
* in the documentation or other materials provided with the distribution
* and in all advertising materials mentioning features or use of this
* software. Neither the name of the University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char sccsid[] = "@(#)tftpsubs.c 5.5 (Berkeley) 6/1/90";
#endif /* not lint */
/* Simple minded read-ahead/write-behind subroutines for tftp user and
server. Written originally with multiple buffers in mind, but current
implementation has two buffer logic wired in.
Todo: add some sort of final error check so when the write-buffer
is finally flushed, the caller can detect if the disk filled up
(or had an i/o error) and return a nak to the other side.
Jim Guyton 10/85
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/tftp.h>
#include <stdio.h>
#define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */
struct bf {
int counter; /* size of data in buffer, or flag */
char buf[PKTSIZE]; /* room for data packet */
} bfs[2];
/* Values for bf.counter */
#define BF_ALLOC -3 /* alloc'd but not yet filled */
#define BF_FREE -2 /* free */
/* [-1 .. SEGSIZE] = size of data in the data buffer */
static int nextone; /* index of next buffer to use */
static int current; /* index of buffer in use */
/* control flags for crlf conversions */
int newline = 0; /* fillbuf: in middle of newline expansion */
int prevchar = -1; /* putbuf: previous char (cr check) */
struct tftphdr *rw_init();
struct tftphdr *w_init() { return rw_init(0); } /* write-behind */
struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */
struct tftphdr *
rw_init(x) /* init for either read-ahead or write-behind */
int x; /* zero for write-behind, one for read-head */
{
newline = 0; /* init crlf flag */
prevchar = -1;
bfs[0].counter = BF_ALLOC; /* pass out the first buffer */
current = 0;
bfs[1].counter = BF_FREE;
nextone = x; /* ahead or behind? */
return (struct tftphdr *)bfs[0].buf;
}
/* Have emptied current buffer by sending to net and getting ack.
Free it and return next buffer filled with data.
*/
readit(file, dpp, convert)
FILE *file; /* file opened for read */
struct tftphdr **dpp;
int convert; /* if true, convert to ascii */
{
struct bf *b;
bfs[current].counter = BF_FREE; /* free old one */
current = !current; /* "incr" current */
b = &bfs[current]; /* look at new buffer */
if (b->counter == BF_FREE) /* if it's empty */
read_ahead(file, convert); /* fill it */
/* assert(b->counter != BF_FREE); /* check */
*dpp = (struct tftphdr *)b->buf; /* set caller's ptr */
return b->counter;
}
/*
* fill the input buffer, doing ascii conversions if requested
* conversions are lf -> cr,lf and cr -> cr, nul
*/
read_ahead(file, convert)
FILE *file; /* file opened for read */
int convert; /* if true, convert to ascii */
{
register int i;
register char *p;
register int c;
struct bf *b;
struct tftphdr *dp;
b = &bfs[nextone]; /* look at "next" buffer */
if (b->counter != BF_FREE) /* nop if not free */
return;
nextone = !nextone; /* "incr" next buffer ptr */
dp = (struct tftphdr *)b->buf;
if (convert == 0) {
b->counter = read(fileno(file), dp->th_data, SEGSIZE);
return;
}
p = dp->th_data;
for (i = 0 ; i < SEGSIZE; i++) {
if (newline) {
if (prevchar == '\n')
c = '\n'; /* lf to cr,lf */
else c = '\0'; /* cr to cr,nul */
newline = 0;
}
else {
c = getc(file);
if (c == EOF) break;
if (c == '\n' || c == '\r') {
prevchar = c;
c = '\r';
newline = 1;
}
}
*p++ = c;
}
b->counter = (int)(p - dp->th_data);
}
/* Update count associated with the buffer, get new buffer
from the queue. Calls write_behind only if next buffer not
available.
*/
writeit(file, dpp, ct, convert)
FILE *file;
struct tftphdr **dpp;
int convert;
{
bfs[current].counter = ct; /* set size of data to write */
current = !current; /* switch to other buffer */
if (bfs[current].counter != BF_FREE) /* if not free */
write_behind(file, convert); /* flush it */
bfs[current].counter = BF_ALLOC; /* mark as alloc'd */
*dpp = (struct tftphdr *)bfs[current].buf;
return ct; /* this is a lie of course */
}
/*
* Output a buffer to a file, converting from netascii if requested.
* CR,NUL -> CR and CR,LF => LF.
* Note spec is undefined if we get CR as last byte of file or a
* CR followed by anything else. In this case we leave it alone.
*/
write_behind(file, convert)
FILE *file;
int convert;
{
char *buf;
int count;
register int ct;
register char *p;
register int c; /* current character */
struct bf *b;
struct tftphdr *dp;
b = &bfs[nextone];
if (b->counter < -1) /* anything to flush? */
return 0; /* just nop if nothing to do */
count = b->counter; /* remember byte count */
b->counter = BF_FREE; /* reset flag */
dp = (struct tftphdr *)b->buf;
nextone = !nextone; /* incr for next time */
buf = dp->th_data;
if (count <= 0) return -1; /* nak logic? */
if (convert == 0)
return write(fileno(file), buf, count);
p = buf;
ct = count;
while (ct--) { /* loop over the buffer */
c = *p++; /* pick up a character */
if (prevchar == '\r') { /* if prev char was cr */
if (c == '\n') /* if have cr,lf then just */
fseek(file, -1, 1); /* smash lf on top of the cr */
else
if (c == '\0') /* if have cr,nul then */
goto skipit; /* just skip over the putc */
/* else just fall through and allow it */
}
putc(c, file);
skipit:
prevchar = c;
}
return count;
}
/* When an error has occurred, it is possible that the two sides
* are out of synch. Ie: that what I think is the other side's
* response to packet N is really their response to packet N-1.
*
* So, to try to prevent that, we flush all the input queued up
* for us on the network connection on our host.
*
* We return the number of packets we flushed (mostly for reporting
* when trace is active).
*/
int
synchnet(f)
int f; /* socket to flush */
{
int i, j = 0;
char rbuf[PKTSIZE];
struct sockaddr_in from;
int fromlen;
while (1) {
(void) ioctl(f, FIONREAD, &i);
if (i) {
j++;
fromlen = sizeof from;
(void) recvfrom(f, rbuf, sizeof (rbuf), 0,
(caddr_t)&from, &fromlen);
} else {
return(j);
}
}
}