usr.bin/tftp/tftpsubs.c

   1 /*
   2  * Copyright (c) 1983, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)tftpsubs.c       8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.bin/tftp/tftpsubs.c,v 1.3.2.1 2002/04/26 17:22:43 ume Exp $
  35  * $DragonFly: src/usr.bin/tftp/tftpsubs.c,v 1.4 2008/10/16 01:52:33 swildner Exp $
  36  */
  37
  38 /* Simple minded read-ahead/write-behind subroutines for tftp user and
  39    server.  Written originally with multiple buffers in mind, but current
  40    implementation has two buffer logic wired in.
  41
  42    Todo:  add some sort of final error check so when the write-buffer
  43    is finally flushed, the caller can detect if the disk filled up
  44    (or had an i/o error) and return a nak to the other side.
  45
  46                         Jim Guyton 10/85
  47  */
  48
  49 #include <sys/types.h>
  50 #include <sys/socket.h>
  51 #include <sys/ioctl.h>
  52 #include <netinet/in.h>
  53 #include <arpa/tftp.h>
  54
  55 #include <stdio.h>
  56 #include <unistd.h>
  57
  58 #include "tftpsubs.h"
  59
  60 #define PKTSIZE SEGSIZE+4       /* should be moved to tftp.h */
  61
  62 struct bf {
  63         int counter;            /* size of data in buffer, or flag */
  64         char buf[PKTSIZE];      /* room for data packet */
  65 } bfs[2];
  66
  67                                 /* Values for bf.counter  */
  68 #define BF_ALLOC -3             /* alloc'd but not yet filled */
  69 #define BF_FREE  -2             /* free */
  70 /* [-1 .. SEGSIZE] = size of data in the data buffer */
  71
  72 static int nextone;             /* index of next buffer to use */
  73 static int current;             /* index of buffer in use */
  74
  75                                 /* control flags for crlf conversions */
  76 int newline = 0;                /* fillbuf: in middle of newline expansion */
  77 int prevchar = -1;              /* putbuf: previous char (cr check) */
  78
  79 static struct tftphdr *rw_init(int);
  80
  81 struct tftphdr *w_init(void) { return rw_init(0); }         /* write-behind */
  82 struct tftphdr *r_init(void) { return rw_init(1); }         /* read-ahead */
  83
  84 static struct tftphdr *
  85 rw_init(int x           /* zero for write-behind, one for read-head */
  86         )                       /* init for either read-ahead or write-behind */
  87 {
  88         newline = 0;            /* init crlf flag */
  89         prevchar = -1;
  90         bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
  91         current = 0;
  92         bfs[1].counter = BF_FREE;
  93         nextone = x;                    /* ahead or behind? */
  94         return (struct tftphdr *)bfs[0].buf;
  95 }
  96
  97
  98 /* Have emptied current buffer by sending to net and getting ack.
  99    Free it and return next buffer filled with data.
 100  */
 101 int
 102 readit(FILE *file, /* file opened for read */
 103        struct tftphdr **dpp,
 104        int convert /* if true, convert to ascii */
 105        )
 106 {
 107         struct bf *b;
 108
 109         bfs[current].counter = BF_FREE; /* free old one */
 110         current = !current;             /* "incr" current */
 111
 112         b = &bfs[current];              /* look at new buffer */
 113         if (b->counter == BF_FREE)      /* if it's empty */
 114                 read_ahead(file, convert);      /* fill it */
 115 /*      assert(b->counter != BF_FREE);*//* check */
 116         *dpp = (struct tftphdr *)b->buf;        /* set caller's ptr */
 117         return b->counter;
 118 }
 119
 120 /*
 121  * fill the input buffer, doing ascii conversions if requested
 122  * conversions are  lf -> cr,lf  and cr -> cr, nul
 123  */
 124 void
 125 read_ahead(FILE *file, int convert)
 126 {
 127         int i;
 128         char *p;
 129         int c;
 130         struct bf *b;
 131         struct tftphdr *dp;
 132
 133         b = &bfs[nextone];              /* look at "next" buffer */
 134         if (b->counter != BF_FREE)      /* nop if not free */
 135                 return;
 136         nextone = !nextone;             /* "incr" next buffer ptr */
 137
 138         dp = (struct tftphdr *)b->buf;
 139
 140         if (convert == 0) {
 141                 b->counter = read(fileno(file), dp->th_data, SEGSIZE);
 142                 return;
 143         }
 144
 145         p = dp->th_data;
 146         for (i = 0 ; i < SEGSIZE; i++) {
 147                 if (newline) {
 148                         if (prevchar == '\n')
 149                                 c = '\n';       /* lf to cr,lf */
 150                         else    c = '\0';       /* cr to cr,nul */
 151                         newline = 0;
 152                 }
 153                 else {
 154                         c = getc(file);
 155                         if (c == EOF) break;
 156                         if (c == '\n' || c == '\r') {
 157                                 prevchar = c;
 158                                 c = '\r';
 159                                 newline = 1;
 160                         }
 161                 }
 162                *p++ = c;
 163         }
 164         b->counter = (int)(p - dp->th_data);
 165 }
 166
 167 /* Update count associated with the buffer, get new buffer
 168    from the queue.  Calls write_behind only if next buffer not
 169    available.
 170  */
 171 int
 172 writeit(FILE *file, struct tftphdr **dpp, int ct, int convert)
 173 {
 174         bfs[current].counter = ct;      /* set size of data to write */
 175         current = !current;             /* switch to other buffer */
 176         if (bfs[current].counter != BF_FREE)     /* if not free */
 177                 (void)write_behind(file, convert); /* flush it */
 178         bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
 179         *dpp =  (struct tftphdr *)bfs[current].buf;
 180         return ct;                      /* this is a lie of course */
 181 }
 182
 183 /*
 184  * Output a buffer to a file, converting from netascii if requested.
 185  * CR,NUL -> CR  and CR,LF => LF.
 186  * Note spec is undefined if we get CR as last byte of file or a
 187  * CR followed by anything else.  In this case we leave it alone.
 188  */
 189 int
 190 write_behind(FILE *file, int convert)
 191 {
 192         char *buf;
 193         int count;
 194         int ct;
 195         char *p;
 196         int c;                          /* current character */
 197         struct bf *b;
 198         struct tftphdr *dp;
 199
 200         b = &bfs[nextone];
 201         if (b->counter < -1)            /* anything to flush? */
 202                 return 0;               /* just nop if nothing to do */
 203
 204         count = b->counter;             /* remember byte count */
 205         b->counter = BF_FREE;           /* reset flag */
 206         dp = (struct tftphdr *)b->buf;
 207         nextone = !nextone;             /* incr for next time */
 208         buf = dp->th_data;
 209
 210         if (count <= 0) return -1;      /* nak logic? */
 211
 212         if (convert == 0)
 213                 return write(fileno(file), buf, count);
 214
 215         p = buf;
 216         ct = count;
 217         while (ct--) {                  /* loop over the buffer */
 218             c = *p++;                   /* pick up a character */
 219             if (prevchar == '\r') {     /* if prev char was cr */
 220                 if (c == '\n')          /* if have cr,lf then just */
 221                    fseek(file, -1, 1);  /* smash lf on top of the cr */
 222                 else
 223                    if (c == '\0')       /* if have cr,nul then */
 224                         goto skipit;    /* just skip over the putc */
 225                 /* else just fall through and allow it */
 226             }
 227             putc(c, file);
 228 skipit:
 229             prevchar = c;
 230         }
 231         return count;
 232 }
 233
 234
 235 /* When an error has occurred, it is possible that the two sides
 236  * are out of synch.  Ie: that what I think is the other side's
 237  * response to packet N is really their response to packet N-1.
 238  *
 239  * So, to try to prevent that, we flush all the input queued up
 240  * for us on the network connection on our host.
 241  *
 242  * We return the number of packets we flushed (mostly for reporting
 243  * when trace is active).
 244  */
 245
 246 int
 247 synchnet(int f)
 248 {
 249         int i, j = 0;
 250         char rbuf[PKTSIZE];
 251         struct sockaddr_storage from;
 252         int fromlen;
 253
 254         while (1) {
 255                 (void) ioctl(f, FIONREAD, &i);
 256                 if (i) {
 257                         j++;
 258                         fromlen = sizeof from;
 259                         (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
 260                                 (struct sockaddr *)&from, &fromlen);
 261                 } else {
 262                         return(j);
 263                 }
 264         }
 265 }