tftpsubs.c revision 1.10
1/* $OpenBSD: tftpsubs.c,v 1.10 2006/07/12 16:58:51 mglocker 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#ifndef lint 34#if 0 35static char sccsid[] = "@(#)tftpsubs.c 8.1 (Berkeley) 6/6/93"; 36#endif 37static const char rcsid[] = 38 "$OpenBSD: tftpsubs.c,v 1.10 2006/07/12 16:58:51 mglocker Exp $"; 39#endif /* not lint */ 40 41/* 42 * Simple minded read-ahead/write-behind subroutines for tftp user and 43 * server. Written originally with multiple buffers in mind, but current 44 * implementation has two buffer logic wired in. 45 * 46 * Todo: add some sort of final error check so when the write-buffer 47 * is finally flushed, the caller can detect if the disk filled up 48 * (or had an i/o error) and return a nak to the other side. 49 * 50 * Jim Guyton 10/85 51 */ 52 53#include <sys/types.h> 54#include <sys/socket.h> 55#include <sys/ioctl.h> 56 57#include <netinet/in.h> 58#include <arpa/tftp.h> 59 60#include <stdio.h> 61#include <unistd.h> 62 63#include "tftpsubs.h" 64 65#define PKTSIZE SEGSIZE + 4 /* should be moved to tftp.h */ 66 /* values for bf.counter */ 67#define BF_ALLOC -3 /* alloc'd but not yet filled */ 68#define BF_FREE -2 /* free */ 69/* [-1 .. SEGSIZE] = size of data in the data buffer */ 70 71static struct tftphdr *rw_init(int); 72 73struct bf { 74 int counter; /* size of data in buffer, or flag */ 75 char buf[PKTSIZE]; /* room for data packet */ 76} bfs[2]; 77 78static int nextone; /* index of next buffer to use */ 79static int current; /* index of buffer in use */ 80 /* control flags for crlf conversions */ 81int newline = 0; /* fillbuf: in middle of newline expansion */ 82int prevchar = -1; /* putbuf: previous char (cr check) */ 83 84struct tftphdr * 85w_init(void) 86{ 87 return (rw_init(0)); /* write-behind */ 88} 89 90struct tftphdr * 91r_init(void) 92{ 93 return (rw_init(1)); /* read-ahead */ 94} 95 96/* 97 * Init for either read-ahead or write-behind. 98 * Zero for write-behind, one for read-head. 99 */ 100static struct tftphdr * 101rw_init(int x) 102{ 103 newline = 0; /* init crlf flag */ 104 prevchar = -1; 105 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 106 current = 0; 107 bfs[1].counter = BF_FREE; 108 nextone = x; /* ahead or behind? */ 109 110 return ((struct tftphdr *)bfs[0].buf); 111} 112 113/* 114 * Have emptied current buffer by sending to net and getting ack. 115 * Free it and return next buffer filled with data. 116 */ 117int 118readit(FILE *file, struct tftphdr **dpp, int convert) 119{ 120 struct bf *b; 121 122 bfs[current].counter = BF_FREE; /* free old one */ 123 current = !current; /* "incr" current */ 124 125 b = &bfs[current]; /* look at new buffer */ 126 if (b->counter == BF_FREE) /* if it's empty */ 127 read_ahead(file, convert); /* fill it */ 128 /* assert(b->counter != BF_FREE); */ /* check */ 129 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 130 131 return (b->counter); 132} 133 134/* 135 * Fill the input buffer, doing ascii conversions if requested. 136 * Conversions are lf -> cr, lf and cr -> cr, nul. 137 */ 138void 139read_ahead(FILE *file, int convert) 140{ 141 int i; 142 char *p; 143 int c; 144 struct bf *b; 145 struct tftphdr *dp; 146 147 b = &bfs[nextone]; /* look at "next" buffer */ 148 if (b->counter != BF_FREE) /* nop if not free */ 149 return; 150 nextone = !nextone; /* "incr" next buffer ptr */ 151 152 dp = (struct tftphdr *)b->buf; 153 154 if (convert == 0) { 155 b->counter = read(fileno(file), dp->th_data, SEGSIZE); 156 return; 157 } 158 159 p = dp->th_data; 160 for (i = 0; i < SEGSIZE; i++) { 161 if (newline) { 162 if (prevchar == '\n') 163 c = '\n'; /* lf to cr, lf */ 164 else 165 c = '\0'; /* cr to cr, nul */ 166 newline = 0; 167 } else { 168 c = getc(file); 169 if (c == EOF) 170 break; 171 if (c == '\n' || c == '\r') { 172 prevchar = c; 173 c = '\r'; 174 newline = 1; 175 } 176 } 177 *p++ = c; 178 } 179 b->counter = (int)(p - dp->th_data); 180} 181 182/* 183 * Update count associated with the buffer, get new buffer 184 * from the queue. Calls write_behind only if next buffer not 185 * available. 186 */ 187int 188writeit(FILE *file, struct tftphdr **dpp, int ct, int convert) 189{ 190 bfs[current].counter = ct; /* set size of data to write */ 191 current = !current; /* switch to other buffer */ 192 if (bfs[current].counter != BF_FREE) /* if not free */ 193 /* flush it */ 194 (void)write_behind(file, convert); 195 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 196 *dpp = (struct tftphdr *)bfs[current].buf; 197 198 return (ct); /* this is a lie of course */ 199} 200 201/* 202 * Output a buffer to a file, converting from netascii if requested. 203 * CR, NUL -> CR and CR, LF -> LF. 204 * Note spec is undefined if we get CR as last byte of file or a 205 * CR followed by anything else. In this case we leave it alone. 206 */ 207int 208write_behind(FILE *file, int convert) 209{ 210 char *buf; 211 int count; 212 int ct; 213 char *p; 214 int c; /* current character */ 215 struct bf *b; 216 struct tftphdr *dp; 217 218 b = &bfs[nextone]; 219 if (b->counter < -1) /* anything to flush? */ 220 return (0); /* just nop if nothing to do */ 221 222 count = b->counter; /* remember byte count */ 223 b->counter = BF_FREE; /* reset flag */ 224 dp = (struct tftphdr *)b->buf; 225 nextone = !nextone; /* incr for next time */ 226 buf = dp->th_data; 227 228 if (count <= 0) /* nak logic? */ 229 return (-1); 230 231 if (convert == 0) 232 return (write(fileno(file), buf, count)); 233 234 p = buf; 235 ct = count; 236 while (ct--) { /* loop over the buffer */ 237 c = *p++; /* pick up a character */ 238 if (prevchar == '\r') { /* if prev char was cr */ 239 if (c == '\n') /* if have cr,lf then just */ 240 /* smash lf on top of the cr */ 241 fseek(file, -1, 1); 242 else if (c == '\0') /* if have cr,nul then */ 243 goto skipit; /* just skip over the putc */ 244 /* FALLTHROUGH */ 245 } 246 putc(c, file); 247skipit: 248 prevchar = c; 249 } 250 251 return (count); 252} 253 254/* 255 * When an error has occurred, it is possible that the two sides 256 * are out of synch. Ie: that what I think is the other side's 257 * response to packet N is really their response to packet N-1. 258 * 259 * So, to try to prevent that, we flush all the input queued up 260 * for us on the network connection on our host. 261 * 262 * We return the number of packets we flushed (mostly for reporting 263 * when trace is active). 264 */ 265int 266synchnet(int f) 267{ 268 int i, j = 0; 269 char rbuf[PKTSIZE]; 270 struct sockaddr_in from; 271 socklen_t fromlen; 272 273 for (;;) { 274 (void)ioctl(f, FIONREAD, &i); 275 if (i) { 276 j++; 277 fromlen = sizeof(from); 278 (void)recvfrom(f, rbuf, sizeof(rbuf), 0, 279 (struct sockaddr *)&from, &fromlen); 280 } else 281 return (j); 282 } 283} 284