1 /* $OpenBSD: tftpsubs.c,v 1.15 2012/05/01 04:23:21 gsoares Exp $ */ 2 /* $NetBSD: tftpsubs.c,v 1.3 1994/12/08 09:51:31 jtc Exp $ */ 3 4 /* 5 * Copyright (c) 1983, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 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 49 #include <netinet/in.h> 50 #include <arpa/tftp.h> 51 52 #include <stdio.h> 53 #include <unistd.h> 54 55 #include "tftpsubs.h" 56 57 /* values for bf.counter */ 58 #define BF_ALLOC -3 /* alloc'd but not yet filled */ 59 #define BF_FREE -2 /* free */ 60 /* [-1 .. SEGSIZE] = size of data in the data buffer */ 61 62 static struct tftphdr *rw_init(int); 63 64 struct bf { 65 int counter; /* size of data in buffer, or flag */ 66 char buf[SEGSIZE_MAX + 4]; /* room for data packet */ 67 } bfs[2]; 68 69 static int nextone; /* index of next buffer to use */ 70 static int current; /* index of buffer in use */ 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 struct tftphdr * 76 w_init(void) 77 { 78 return (rw_init(0)); /* write-behind */ 79 } 80 81 struct tftphdr * 82 r_init(void) 83 { 84 return (rw_init(1)); /* read-ahead */ 85 } 86 87 /* 88 * Init for either read-ahead or write-behind. 89 * Zero for write-behind, one for read-head. 90 */ 91 static struct tftphdr * 92 rw_init(int x) 93 { 94 newline = 0; /* init crlf flag */ 95 prevchar = -1; 96 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 97 current = 0; 98 bfs[1].counter = BF_FREE; 99 nextone = x; /* ahead or behind? */ 100 101 return ((struct tftphdr *)bfs[0].buf); 102 } 103 104 /* 105 * Have emptied current buffer by sending to net and getting ack. 106 * Free it and return next buffer filled with data. 107 */ 108 int 109 readit(FILE *file, struct tftphdr **dpp, int convert, int segment_size) 110 { 111 struct bf *b; 112 113 bfs[current].counter = BF_FREE; /* free old one */ 114 current = !current; /* "incr" current */ 115 116 b = &bfs[current]; /* look at new buffer */ 117 if (b->counter == BF_FREE) /* if it's empty */ 118 read_ahead(file, convert, segment_size); /* fill it */ 119 /* assert(b->counter != BF_FREE); */ /* check */ 120 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 121 122 return (b->counter); 123 } 124 125 /* 126 * Fill the input buffer, doing ascii conversions if requested. 127 * Conversions are lf -> cr, lf and cr -> cr, nul. 128 */ 129 void 130 read_ahead(FILE *file, int convert, int segment_size) 131 { 132 int i; 133 char *p; 134 int c; 135 struct bf *b; 136 struct tftphdr *dp; 137 138 b = &bfs[nextone]; /* look at "next" buffer */ 139 if (b->counter != BF_FREE) /* nop if not free */ 140 return; 141 nextone = !nextone; /* "incr" next buffer ptr */ 142 143 dp = (struct tftphdr *)b->buf; 144 145 if (convert == 0) { 146 b->counter = read(fileno(file), dp->th_data, segment_size); 147 return; 148 } 149 150 p = dp->th_data; 151 for (i = 0; i < segment_size; i++) { 152 if (newline) { 153 if (prevchar == '\n') 154 c = '\n'; /* lf to cr, lf */ 155 else 156 c = '\0'; /* cr to cr, nul */ 157 newline = 0; 158 } else { 159 c = getc(file); 160 if (c == EOF) 161 break; 162 if (c == '\n' || c == '\r') { 163 prevchar = c; 164 c = '\r'; 165 newline = 1; 166 } 167 } 168 *p++ = c; 169 } 170 b->counter = (int)(p - dp->th_data); 171 } 172 173 /* 174 * Update count associated with the buffer, get new buffer 175 * from the queue. Calls write_behind only if next buffer not 176 * available. 177 */ 178 int 179 writeit(FILE *file, struct tftphdr **dpp, int ct, int convert) 180 { 181 bfs[current].counter = ct; /* set size of data to write */ 182 current = !current; /* switch to other buffer */ 183 if (bfs[current].counter != BF_FREE) /* if not free */ 184 /* flush it */ 185 (void)write_behind(file, convert); 186 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 187 *dpp = (struct tftphdr *)bfs[current].buf; 188 189 return (ct); /* this is a lie of course */ 190 } 191 192 /* 193 * Output a buffer to a file, converting from netascii if requested. 194 * CR, NUL -> CR and CR, LF -> LF. 195 * Note spec is undefined if we get CR as last byte of file or a 196 * CR followed by anything else. In this case we leave it alone. 197 */ 198 int 199 write_behind(FILE *file, int convert) 200 { 201 char *buf; 202 int count; 203 int ct; 204 char *p; 205 int c; /* current character */ 206 struct bf *b; 207 struct tftphdr *dp; 208 209 b = &bfs[nextone]; 210 if (b->counter < -1) /* anything to flush? */ 211 return (0); /* just nop if nothing to do */ 212 213 count = b->counter; /* remember byte count */ 214 b->counter = BF_FREE; /* reset flag */ 215 dp = (struct tftphdr *)b->buf; 216 nextone = !nextone; /* incr for next time */ 217 buf = dp->th_data; 218 219 if (count <= 0) /* nak logic? */ 220 return (-1); 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 /* smash lf on top of the cr */ 232 fseek(file, -1, SEEK_CUR); 233 else if (c == '\0') /* if have cr,nul then */ 234 goto skipit; /* just skip over the putc */ 235 /* FALLTHROUGH */ 236 } 237 putc(c, file); 238 skipit: 239 prevchar = c; 240 } 241 242 return (count); 243 } 244 245 /* 246 * When an error has occurred, it is possible that the two sides 247 * are out of synch. Ie: that what I think is the other side's 248 * response to packet N is really their response to packet N-1. 249 * 250 * So, to try to prevent that, we flush all the input queued up 251 * for us on the network connection on our host. 252 * 253 * We return the number of packets we flushed (mostly for reporting 254 * when trace is active). 255 */ 256 int 257 synchnet(int f) 258 { 259 int i, j = 0; 260 char rbuf[SEGSIZE_MIN]; 261 struct sockaddr_storage from; 262 socklen_t fromlen; 263 264 for (;;) { 265 (void)ioctl(f, FIONREAD, &i); 266 if (i) { 267 j++; 268 fromlen = sizeof(from); 269 (void)recvfrom(f, rbuf, sizeof(rbuf), 0, 270 (struct sockaddr *)&from, &fromlen); 271 } else 272 return (j); 273 } 274 } 275