usr.bin/tftp/tftpsubs.c

   1 /*      $NetBSD: tftpsubs.c,v 1.10 2006/04/09 18:45:19 christos Exp $   */
   2
   3 /*
   4  * Copyright (c) 1983, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)tftpsubs.c  8.1 (Berkeley) 6/6/93";
  36 #else
  37 __RCSID("$NetBSD: tftpsubs.c,v 1.10 2006/04/09 18:45:19 christos Exp $");
  38 #endif
  39 #endif /* not lint */
  40
  41 /* Simple minded read-ahead/write-behind subroutines for tftp user and
  42    server.  Written originally with multiple buffers in mind, but current
  43    implementation has two buffer logic wired in.
  44
  45    Todo:  add some sort of final error check so when the write-buffer
  46    is finally flushed, the caller can detect if the disk filled up
  47    (or had an i/o error) and return a nak to the other side.
  48
  49                         Jim Guyton 10/85
  50  */
  51
  52 #include <sys/types.h>
  53 #include <sys/socket.h>
  54 #include <sys/ioctl.h>
  55 #include <netinet/in.h>
  56 #include <arpa/tftp.h>
  57
  58 #include <stdio.h>
  59 #include <unistd.h>
  60
  61 #include "tftpsubs.h"
  62
  63 struct bf {
  64         int counter;            /* size of data in buffer, or flag */
  65         char buf[MAXPKTSIZE];   /* room for data packet */
  66 } bfs[2];
  67
  68                                 /* Values for bf.counter  */
  69 #define BF_ALLOC -3             /* alloc'd but not yet filled */
  70 #define BF_FREE  -2             /* free */
  71 /* [-1 .. SEGSIZE] = size of data in the data buffer */
  72
  73 static int nextone;             /* index of next buffer to use */
  74 static int current;             /* index of buffer in use */
  75
  76                                 /* control flags for crlf conversions */
  77 int newline = 0;                /* fillbuf: in middle of newline expansion */
  78 int prevchar = -1;              /* putbuf: previous char (cr check) */
  79
  80 static struct tftphdr *rw_init __P((int));
  81
  82 struct tftphdr *
  83 w_init()                /* write-behind */
  84 {
  85         return rw_init(0);
  86 }
  87
  88 struct tftphdr *
  89 r_init()                /* read-ahead */
  90 {
  91         return rw_init(1);
  92 }
  93
  94 static struct tftphdr *
  95 rw_init(x)                      /* init for either read-ahead or write-behind */
  96         int x;                  /* zero for write-behind, one for read-head */
  97 {
  98         newline = 0;            /* init crlf flag */
  99         prevchar = -1;
 100         bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
 101         current = 0;
 102         bfs[1].counter = BF_FREE;
 103         nextone = x;                    /* ahead or behind? */
 104         return (struct tftphdr *)(void *)bfs[0].buf;
 105 }
 106
 107 /* Have emptied current buffer by sending to net and getting ack.
 108    Free it and return next buffer filled with data.
 109  */
 110 int
 111 readit(file, dpp, amt, convert)
 112         FILE *file;                     /* file opened for read */
 113         struct tftphdr **dpp;
 114         size_t amt;
 115         int convert;                    /* if true, convert to ascii */
 116 {
 117         struct bf *b;
 118
 119         bfs[current].counter = BF_FREE; /* free old one */
 120         current = !current;             /* "incr" current */
 121
 122         b = &bfs[current];              /* look at new buffer */
 123         if (b->counter == BF_FREE)      /* if it's empty */
 124                 read_ahead(file, amt, convert);      /* fill it */
 125 /*      assert(b->counter != BF_FREE);*//* check */
 126         *dpp = (struct tftphdr *)(void *)b->buf;        /* set caller's ptr */
 127         return b->counter;
 128 }
 129
 130 /*
 131  * fill the input buffer, doing ascii conversions if requested
 132  * conversions are  lf -> cr,lf  and cr -> cr, nul
 133  */
 134 void
 135 read_ahead(file, amt, convert)
 136         FILE *file;                     /* file opened for read */
 137         size_t amt;                     /* number of bytes to read */
 138         int convert;                    /* if true, convert to ascii */
 139 {
 140         size_t i;
 141         char *p;
 142         int c;
 143         struct bf *b;
 144         struct tftphdr *dp;
 145
 146         b = &bfs[nextone];              /* look at "next" buffer */
 147         if (b->counter != BF_FREE)      /* nop if not free */
 148                 return;
 149         nextone = !nextone;             /* "incr" next buffer ptr */
 150
 151         dp = (struct tftphdr *)(void *)b->buf;
 152
 153         if (convert == 0) {
 154                 b->counter = read(fileno(file), dp->th_data, amt);
 155                 return;
 156         }
 157
 158         p = dp->th_data;
 159         for (i = 0 ; i < amt; i++) {
 160                 if (newline) {
 161                         if (prevchar == '\n')
 162                                 c = '\n';       /* lf to cr,lf */
 163                         else    c = '\0';       /* cr to cr,nul */
 164                         newline = 0;
 165                 }
 166                 else {
 167                         c = getc(file);
 168                         if (c == EOF) break;
 169                         if (c == '\n' || c == '\r') {
 170                                 prevchar = c;
 171                                 c = '\r';
 172                                 newline = 1;
 173                         }
 174                 }
 175                *p++ = c;
 176         }
 177         b->counter = (int)(p - dp->th_data);
 178 }
 179
 180 /* Update count associated with the buffer, get new buffer
 181    from the queue.  Calls write_behind only if next buffer not
 182    available.
 183  */
 184 int
 185 writeit(file, dpp, ct, convert)
 186         FILE *file;
 187         struct tftphdr **dpp;
 188         int ct, convert;
 189 {
 190         bfs[current].counter = ct;      /* set size of data to write */
 191         current = !current;             /* switch to other buffer */
 192         if (bfs[current].counter != BF_FREE)     /* if not free */
 193                 if (write_behind(file, convert) == -1) /* flush it */
 194                         return -1;
 195         bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
 196         *dpp =  (struct tftphdr *)(void *)bfs[current].buf;
 197         return ct;                      /* this is a lie of course */
 198 }
 199
 200 /*
 201  * Output a buffer to a file, converting from netascii if requested.
 202  * CR,NUL -> CR  and CR,LF => LF.
 203  * Note spec is undefined if we get CR as last byte of file or a
 204  * CR followed by anything else.  In this case we leave it alone.
 205  */
 206 int
 207 write_behind(file, convert)
 208         FILE *file;
 209         int convert;
 210 {
 211         char *buf;
 212         int count;
 213         int ct;
 214         char *p;
 215         int c;                          /* current character */
 216         struct bf *b;
 217         struct tftphdr *dp;
 218
 219         b = &bfs[nextone];
 220         if (b->counter < -1)            /* anything to flush? */
 221                 return 0;               /* just nop if nothing to do */
 222
 223         count = b->counter;             /* remember byte count */
 224         b->counter = BF_FREE;           /* reset flag */
 225         dp = (struct tftphdr *)(void *)b->buf;
 226         nextone = !nextone;             /* incr for next time */
 227         buf = dp->th_data;
 228
 229         if (count <= 0) return -1;      /* nak logic? */
 230
 231         if (convert == 0)
 232                 return write(fileno(file), buf, (size_t)count);
 233
 234         p = buf;
 235         ct = count;
 236         while (ct--) {                  /* loop over the buffer */
 237             c = *p++;                   /* pick up a character */
 238             if (prevchar == '\r') {     /* if prev char was cr */
 239                 if (c == '\n')          /* if have cr,lf then just */
 240                    (void)fseeko(file, (off_t)-1, 1);  /* smash lf on top of the cr */
 241                 else
 242                    if (c == '\0')       /* if have cr,nul then */
 243                         goto skipit;    /* just skip over the putc */
 244                 /* else just fall through and allow it */
 245             }
 246             if (putc(c, file) == EOF)
 247                 return -1;
 248 skipit:
 249             prevchar = c;
 250         }
 251         return count;
 252 }
 253
 254
 255 /* When an error has occurred, it is possible that the two sides
 256  * are out of synch.  Ie: that what I think is the other side's
 257  * response to packet N is really their response to packet N-1.
 258  *
 259  * So, to try to prevent that, we flush all the input queued up
 260  * for us on the network connection on our host.
 261  *
 262  * We return the number of packets we flushed (mostly for reporting
 263  * when trace is active).
 264  */
 265
 266 int
 267 /*ARGSUSED*/
 268 synchnet(f, bsize)
 269         int     f;              /* socket to flush */
 270         size_t  bsize;          /* size of buffer to sync */
 271 {
 272         int i, j = 0;
 273         char rbuf[PKTSIZE];
 274         struct sockaddr_storage from;
 275         socklen_t fromlen;
 276
 277         for (;;) {
 278                 (void) ioctl(f, FIONREAD, &i);
 279                 if (i) {
 280                         j++;
 281                         fromlen = sizeof from;
 282                         (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
 283                                 (struct sockaddr *)(void *)&from, &fromlen);
 284                 } else {
 285                         return(j);
 286                 }
 287         }
 288 }