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