usr/src/ucb/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 the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)tftpsubs.c  5.4 (Berkeley) 6/29/88";
#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);
                }
        }
}