tftp/tftpsubs.c

   1 /* tftp-hpa: $Id$ */
   2
   3 /* $OpenBSD: tftpsubs.c,v 1.2 1996/06/26 05:40:36 deraadt Exp $ */
   4 /* $NetBSD: tftpsubs.c,v 1.3 1994/12/08 09:51:31 jtc Exp $      */
   5
   6 /*
   7  * Copyright (c) 1983, 1993
   8  *      The Regents of the University of California.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include "tftpsubs.h"
  40
  41 #ifndef lint
  42 /* static char sccsid[] = "@(#)tftpsubs.c       8.1 (Berkeley) 6/6/93"; */
  43 /* static char rcsid[] = "$OpenBSD: tftpsubs.c,v 1.2 1996/06/26 05:40:36 deraadt Exp $"; */
  44 static const char *rcsid UNUSED =
  45 "tftp-hpa: $Id$";
  46 #endif /* not lint */
  47
  48 /* Simple minded read-ahead/write-behind subroutines for tftp user and
  49    server.  Written originally with multiple buffers in mind, but current
  50    implementation has two buffer logic wired in.
  51
  52    Todo:  add some sort of final error check so when the write-buffer
  53    is finally flushed, the caller can detect if the disk filled up
  54    (or had an i/o error) and return a nak to the other side.
  55
  56                         Jim Guyton 10/85
  57  */
  58
  59 #include <sys/types.h>
  60 #include <sys/socket.h>
  61 #include <sys/ioctl.h>
  62 #include <sys/time.h>
  63 #include <netinet/in.h>
  64 #include <arpa/tftp.h>
  65 #include <stdio.h>
  66 #include <unistd.h>
  67
  68 #include "../config.h"
  69
  70 #define PKTSIZE MAX_SEGSIZE+4       /* should be moved to tftp.h */
  71
  72 int segsize = SEGSIZE;          /* Default segsize */
  73
  74 struct bf {
  75         int counter;            /* size of data in buffer, or flag */
  76         char buf[PKTSIZE];      /* room for data packet */
  77 } bfs[2];
  78
  79                                 /* Values for bf.counter  */
  80 #define BF_ALLOC -3             /* alloc'd but not yet filled */
  81 #define BF_FREE  -2             /* free */
  82 /* [-1 .. segsize] = size of data in the data buffer */
  83
  84 static int nextone;             /* index of next buffer to use */
  85 static int current;             /* index of buffer in use */
  86
  87                                 /* control flags for crlf conversions */
  88 int newline = 0;                /* fillbuf: in middle of newline expansion */
  89 int prevchar = -1;              /* putbuf: previous char (cr check) */
  90
  91 static struct tftphdr *rw_init(int);
  92
  93 struct tftphdr *w_init() { return rw_init(0); }         /* write-behind */
  94 struct tftphdr *r_init() { return rw_init(1); }         /* read-ahead */
  95
  96 /* init for either read-ahead or write-behind */
  97 /* x == zero for write-behind, one for read-head */
  98 static struct tftphdr *
  99 rw_init(int x)
 100 {
 101         newline = 0;            /* init crlf flag */
 102         prevchar = -1;
 103         bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
 104         current = 0;
 105         bfs[1].counter = BF_FREE;
 106         nextone = x;                    /* ahead or behind? */
 107         return (struct tftphdr *)bfs[0].buf;
 108 }
 109
 110
 111 /* Have emptied current buffer by sending to net and getting ack.
 112    Free it and return next buffer filled with data.
 113  */
 114 int
 115 readit(FILE *file, struct tftphdr **dpp, int convert)
 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, convert);      /* fill it */
 125 /*      assert(b->counter != BF_FREE);*//* check */
 126         *dpp = (struct tftphdr *)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 *file, int convert)
 136 {
 137         int i;
 138         char *p;
 139         int c;
 140         struct bf *b;
 141         struct tftphdr *dp;
 142
 143         b = &bfs[nextone];              /* look at "next" buffer */
 144         if (b->counter != BF_FREE)      /* nop if not free */
 145                 return;
 146         nextone = !nextone;             /* "incr" next buffer ptr */
 147
 148         dp = (struct tftphdr *)b->buf;
 149
 150         if (convert == 0) {
 151                 b->counter = read(fileno(file), dp->th_data, segsize);
 152                 return;
 153         }
 154
 155         p = dp->th_data;
 156         for (i = 0 ; i < segsize; i++) {
 157                 if (newline) {
 158                         if (prevchar == '\n')
 159                                 c = '\n';       /* lf to cr,lf */
 160                         else    c = '\0';       /* cr to cr,nul */
 161                         newline = 0;
 162                 }
 163                 else {
 164                         c = getc(file);
 165                         if (c == EOF) break;
 166                         if (c == '\n' || c == '\r') {
 167                                 prevchar = c;
 168                                 c = '\r';
 169                                 newline = 1;
 170                         }
 171                 }
 172                *p++ = c;
 173         }
 174         b->counter = (int)(p - dp->th_data);
 175 }
 176
 177 /* Update count associated with the buffer, get new buffer
 178    from the queue.  Calls write_behind only if next buffer not
 179    available.
 180  */
 181 int
 182 writeit(FILE *file, struct tftphdr **dpp, int ct, int convert)
 183 {
 184         bfs[current].counter = ct;      /* set size of data to write */
 185         current = !current;             /* switch to other buffer */
 186         if (bfs[current].counter != BF_FREE)     /* if not free */
 187                 (void)write_behind(file, convert); /* flush it */
 188         bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
 189         *dpp =  (struct tftphdr *)bfs[current].buf;
 190         return ct;                      /* this is a lie of course */
 191 }
 192
 193 /*
 194  * Output a buffer to a file, converting from netascii if requested.
 195  * CR,NUL -> CR  and CR,LF => LF.
 196  * Note spec is undefined if we get CR as last byte of file or a
 197  * CR followed by anything else.  In this case we leave it alone.
 198  */
 199 int
 200 write_behind(FILE *file, int convert)
 201 {
 202         char *buf;
 203         int count;
 204         int ct;
 205         char *p;
 206         int c;                 /* current character */
 207         struct bf *b;
 208         struct tftphdr *dp;
 209
 210         b = &bfs[nextone];
 211         if (b->counter < -1)            /* anything to flush? */
 212                 return 0;               /* just nop if nothing to do */
 213
 214         count = b->counter;             /* remember byte count */
 215         b->counter = BF_FREE;           /* reset flag */
 216         dp = (struct tftphdr *)b->buf;
 217         nextone = !nextone;             /* incr for next time */
 218         buf = dp->th_data;
 219
 220         if (count <= 0) return -1;      /* nak logic? */
 221
 222         if (convert == 0)
 223                 return write(fileno(file), buf, count);
 224
 225         p = buf;
 226         ct = count;
 227         while (ct--) {                  /* loop over the buffer */
 228             c = *p++;                   /* pick up a character */
 229             if (prevchar == '\r') {     /* if prev char was cr */
 230                 if (c == '\n')          /* if have cr,lf then just */
 231                    fseek(file, -1, 1);  /* smash lf on top of the cr */
 232                 else
 233                    if (c == '\0')       /* if have cr,nul then */
 234                         goto skipit;    /* just skip over the putc */
 235                 /* else just fall through and allow it */
 236             }
 237             putc(c, file);
 238 skipit:
 239             prevchar = c;
 240         }
 241         return count;
 242 }
 243
 244
 245 /* When an error has occurred, it is possible that the two sides
 246  * are out of synch.  Ie: that what I think is the other side's
 247  * response to packet N is really their response to packet N-1.
 248  *
 249  * So, to try to prevent that, we flush all the input queued up
 250  * for us on the network connection on our host.
 251  *
 252  * We return the number of packets we flushed (mostly for reporting
 253  * when trace is active).
 254  */
 255
 256 int
 257 synchnet(int f)         /* socket to flush */
 258 {
 259   int pktcount = 0;
 260   char rbuf[PKTSIZE];
 261   struct sockaddr_in from;
 262   int fromlen;
 263   fd_set socketset;
 264   struct timeval notime;
 265
 266   while ( 1 ) {
 267     notime.tv_sec = notime.tv_usec = 0;
 268
 269     FD_ZERO(&socketset);
 270     FD_SET(f, &socketset);
 271
 272     if ( select(f, &socketset, NULL, NULL, &notime) <= 0 )
 273       break;                    /* Nothing to read */
 274
 275     /* Otherwise drain the packet */
 276     pktcount++;
 277     fromlen = sizeof from;
 278     (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
 279                     (struct sockaddr *)&from, &fromlen);
 280   }
 281
 282   return pktcount;              /* Return packets drained */
 283 }