contrib/tftp/tftpsubs.c

   1 /*
   2  * Copyright (c) 1983 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * advertising materials, and other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 #ifndef lint
  19 static char sccsid[] = "@(#)tftpsubs.c  5.4 (Berkeley) 6/29/88";
  20 #endif /* not lint */
  21
  22 /* Simple minded read-ahead/write-behind subroutines for tftp user and
  23    server.  Written originally with multiple buffers in mind, but current
  24    implementation has two buffer logic wired in.
  25
  26    Todo:  add some sort of final error check so when the write-buffer
  27    is finally flushed, the caller can detect if the disk filled up
  28    (or had an i/o error) and return a nak to the other side.
  29
  30                         Jim Guyton 10/85
  31  */
  32
  33 #include <errno.h>
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <sys/ioctl.h>
  37 #include <netinet/in.h>
  38 #include <arpa/tftp.h>
  39 #include <stdio.h>
  40
  41 #define PKTSIZE (1432+4) /* SEGSIZE+4 */      /* should be moved to tftp.h */
  42
  43 struct bf {
  44         int counter;            /* size of data in buffer, or flag */
  45         char buf[PKTSIZE];      /* room for data packet */
  46 } bfs[2];
  47
  48                                 /* Values for bf.counter  */
  49 #define BF_ALLOC -3             /* alloc'd but not yet filled */
  50 #define BF_FREE  -2             /* free */
  51 /* [-1 .. SEGSIZE] = size of data in the data buffer */
  52
  53 extern int segsize;
  54
  55 static int nextone;     /* index of next buffer to use */
  56 static int current;     /* index of buffer in use */
  57
  58                         /* control flags for crlf conversions */
  59 int newline = 0;        /* fillbuf: in middle of newline expansion */
  60 int prevchar = -1;      /* putbuf: previous char (cr check) */
  61
  62 struct tftphdr *rw_init();
  63
  64 struct tftphdr *w_init() { return rw_init(0); }         /* write-behind */
  65 struct tftphdr *r_init() { return rw_init(1); }         /* read-ahead */
  66
  67 struct tftphdr *
  68 rw_init(x)              /* init for either read-ahead or write-behind */
  69 int x;                  /* zero for write-behind, one for read-head */
  70 {
  71         newline = 0;            /* init crlf flag */
  72         prevchar = -1;
  73         bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
  74         current = 0;
  75         bfs[1].counter = BF_FREE;
  76         nextone = x;                    /* ahead or behind? */
  77         return (struct tftphdr *)bfs[0].buf;
  78 }
  79
  80
  81 /* Have emptied current buffer by sending to net and getting ack.
  82    Free it and return next buffer filled with data.
  83  */
  84 readit(file, dpp, convert)
  85         FILE *file;                     /* file opened for read */
  86         struct tftphdr **dpp;
  87         int convert;                    /* if true, convert to ascii */
  88 {
  89         struct bf *b;
  90
  91         bfs[current].counter = BF_FREE; /* free old one */
  92         current = !current;             /* "incr" current */
  93
  94         b = &bfs[current];              /* look at new buffer */
  95         if (b->counter == BF_FREE)      /* if it's empty */
  96                 read_ahead(file, convert);      /* fill it */
  97 /*      assert(b->counter != BF_FREE);  /* check */
  98         *dpp = (struct tftphdr *)b->buf;        /* set caller's ptr */
  99         return b->counter;
 100 }
 101
 102 /*
 103  * fill the input buffer, doing ascii conversions if requested
 104  * conversions are  lf -> cr,lf  and cr -> cr, nul
 105  */
 106 read_ahead(file, convert)
 107         FILE *file;                     /* file opened for read */
 108         int convert;                    /* if true, convert to ascii */
 109 {
 110         register int i;
 111         register char *p;
 112         register int c;
 113         struct bf *b;
 114         struct tftphdr *dp;
 115
 116         b = &bfs[nextone];              /* look at "next" buffer */
 117         if (b->counter != BF_FREE)      /* nop if not free */
 118                 return;
 119         nextone = !nextone;             /* "incr" next buffer ptr */
 120
 121         dp = (struct tftphdr *)b->buf;
 122
 123         if (convert == 0) {
 124                 int i;
 125                 b->counter = 0;
 126                 do {
 127                         i = read(fileno(file), dp->th_data + b->counter,
 128                                  segsize - b->counter);
 129                         if (i > 0)
 130                                 b->counter += i;
 131                 } while (i != 0 && !(i < 0 && errno != EINTR) &&
 132                          b->counter < segsize);
 133                 return;
 134         }
 135
 136         p = dp->th_data;
 137         for (i = 0 ; i < segsize; i++) {
 138                 if (newline) {
 139                         if (prevchar == '\n')
 140                                 c = '\n';       /* lf to cr,lf */
 141                         else    c = '\0';       /* cr to cr,nul */
 142                         newline = 0;
 143                 }
 144                 else {
 145                         c = getc(file);
 146                         if (c == EOF) break;
 147                         if (c == '\n' || c == '\r') {
 148                                 prevchar = c;
 149                                 c = '\r';
 150                                 newline = 1;
 151                         }
 152                 }
 153                *p++ = c;
 154         }
 155         b->counter = (int)(p - dp->th_data);
 156 }
 157
 158 /* Update count associated with the buffer, get new buffer
 159    from the queue.  Calls write_behind only if next buffer not
 160    available.
 161  */
 162 writeit(file, dpp, ct, convert)
 163         FILE *file;
 164         struct tftphdr **dpp;
 165         int convert;
 166 {
 167         bfs[current].counter = ct;      /* set size of data to write */
 168         current = !current;             /* switch to other buffer */
 169         if (bfs[current].counter != BF_FREE)     /* if not free */
 170                 write_behind(file, convert);     /* flush it */
 171         bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
 172         *dpp =  (struct tftphdr *)bfs[current].buf;
 173         return ct;                      /* this is a lie of course */
 174 }
 175
 176 /*
 177  * Output a buffer to a file, converting from netascii if requested.
 178  * CR,NUL -> CR  and CR,LF => LF.
 179  * Note spec is undefined if we get CR as last byte of file or a
 180  * CR followed by anything else.  In this case we leave it alone.
 181  */
 182 write_behind(file, convert)
 183         FILE *file;
 184         int convert;
 185 {
 186         char *buf;
 187         int count;
 188         register int ct;
 189         register char *p;
 190         register int c;                 /* current character */
 191         struct bf *b;
 192         struct tftphdr *dp;
 193
 194         b = &bfs[nextone];
 195         if (b->counter < -1)            /* anything to flush? */
 196                 return 0;               /* just nop if nothing to do */
 197
 198         count = b->counter;             /* remember byte count */
 199         b->counter = BF_FREE;           /* reset flag */
 200         dp = (struct tftphdr *)b->buf;
 201         nextone = !nextone;             /* incr for next time */
 202         buf = dp->th_data;
 203
 204         if (count <= 0) return -1;      /* nak logic? */
 205
 206         if (convert == 0)
 207                 return write(fileno(file), buf, count);
 208
 209         p = buf;
 210         ct = count;
 211         while (ct--) {                  /* loop over the buffer */
 212             c = *p++;                   /* pick up a character */
 213             if (prevchar == '\r') {     /* if prev char was cr */
 214                 if (c == '\n')          /* if have cr,lf then just */
 215                    fseek(file, -1, 1);  /* smash lf on top of the cr */
 216                 else
 217                    if (c == '\0')       /* if have cr,nul then */
 218                         goto skipit;    /* just skip over the putc */
 219                 /* else just fall through and allow it */
 220             }
 221             putc(c, file);
 222 skipit:
 223             prevchar = c;
 224         }
 225         return count;
 226 }
 227
 228
 229 /* When an error has occurred, it is possible that the two sides
 230  * are out of synch.  Ie: that what I think is the other side's
 231  * response to packet N is really their response to packet N-1.
 232  *
 233  * So, to try to prevent that, we flush all the input queued up
 234  * for us on the network connection on our host.
 235  *
 236  * We return the number of packets we flushed (mostly for reporting
 237  * when trace is active).
 238  */
 239
 240 int
 241 synchnet(f)
 242 int     f;              /* socket to flush */
 243 {
 244         int i, j = 0;
 245         char rbuf[PKTSIZE];
 246         struct sockaddr_in from;
 247         int fromlen;
 248
 249         while (1) {
 250                 (void) ioctl(f, FIONREAD, &i);
 251                 if (i) {
 252                         j++;
 253                         fromlen = sizeof from;
 254                         (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
 255                                 (struct sockaddr *)&from, &fromlen);
 256                 } else {
 257                         return(j);
 258                 }
 259         }
 260 }