1 /* $OpenBSD: tftpsubs.c,v 1.8 2003/06/26 07:59:49 deraadt 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 35 static char sccsid[] = "@(#)tftpsubs.c 8.1 (Berkeley) 6/6/93"; 36 #endif 37 static const char rcsid[] = "$OpenBSD: tftpsubs.c,v 1.8 2003/06/26 07:59:49 deraadt Exp $"; 38 #endif /* not lint */ 39 40 /* Simple minded read-ahead/write-behind subroutines for tftp user and 41 server. Written originally with multiple buffers in mind, but current 42 implementation has two buffer logic wired in. 43 44 Todo: add some sort of final error check so when the write-buffer 45 is finally flushed, the caller can detect if the disk filled up 46 (or had an i/o error) and return a nak to the other side. 47 48 Jim Guyton 10/85 49 */ 50 51 #include <sys/types.h> 52 #include <sys/socket.h> 53 #include <sys/ioctl.h> 54 #include <netinet/in.h> 55 #include <arpa/tftp.h> 56 57 #include <stdio.h> 58 #include <unistd.h> 59 60 #include "tftpsubs.h" 61 62 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */ 63 64 struct bf { 65 int counter; /* size of data in buffer, or flag */ 66 char buf[PKTSIZE]; /* room for data packet */ 67 } bfs[2]; 68 69 /* Values for bf.counter */ 70 #define BF_ALLOC -3 /* alloc'd but not yet filled */ 71 #define BF_FREE -2 /* free */ 72 /* [-1 .. SEGSIZE] = size of data in the data buffer */ 73 74 static int nextone; /* index of next buffer to use */ 75 static int current; /* index of buffer in use */ 76 77 /* control flags for crlf conversions */ 78 int newline = 0; /* fillbuf: in middle of newline expansion */ 79 int prevchar = -1; /* putbuf: previous char (cr check) */ 80 81 static struct tftphdr *rw_init(int); 82 83 struct tftphdr * 84 w_init(void) 85 { 86 return rw_init(0); /* write-behind */ 87 } 88 89 struct tftphdr * 90 r_init(void) 91 { 92 return rw_init(1); /* read-ahead */ 93 } 94 95 /* init for either read-ahead or write-behind */ 96 /* zero for write-behind, one for read-head */ 97 static struct tftphdr * 98 rw_init(int x) 99 { 100 newline = 0; /* init crlf flag */ 101 prevchar = -1; 102 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 103 current = 0; 104 bfs[1].counter = BF_FREE; 105 nextone = x; /* ahead or behind? */ 106 return (struct tftphdr *)bfs[0].buf; 107 } 108 109 110 /* Have emptied current buffer by sending to net and getting ack. 111 Free it and return next buffer filled with data. 112 */ 113 int 114 readit(FILE *file, struct tftphdr **dpp, int convert) 115 { 116 struct bf *b; 117 118 bfs[current].counter = BF_FREE; /* free old one */ 119 current = !current; /* "incr" current */ 120 121 b = &bfs[current]; /* look at new buffer */ 122 if (b->counter == BF_FREE) /* if it's empty */ 123 read_ahead(file, convert); /* fill it */ 124 /* assert(b->counter != BF_FREE);*//* check */ 125 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 126 return b->counter; 127 } 128 129 /* 130 * fill the input buffer, doing ascii conversions if requested 131 * conversions are lf -> cr,lf and cr -> cr, nul 132 */ 133 void 134 read_ahead(FILE *file, int convert) 135 { 136 int i; 137 char *p; 138 int c; 139 struct bf *b; 140 struct tftphdr *dp; 141 142 b = &bfs[nextone]; /* look at "next" buffer */ 143 if (b->counter != BF_FREE) /* nop if not free */ 144 return; 145 nextone = !nextone; /* "incr" next buffer ptr */ 146 147 dp = (struct tftphdr *)b->buf; 148 149 if (convert == 0) { 150 b->counter = read(fileno(file), dp->th_data, SEGSIZE); 151 return; 152 } 153 154 p = dp->th_data; 155 for (i = 0 ; i < SEGSIZE; i++) { 156 if (newline) { 157 if (prevchar == '\n') 158 c = '\n'; /* lf to cr,lf */ 159 else c = '\0'; /* cr to cr,nul */ 160 newline = 0; 161 } 162 else { 163 c = getc(file); 164 if (c == EOF) break; 165 if (c == '\n' || c == '\r') { 166 prevchar = c; 167 c = '\r'; 168 newline = 1; 169 } 170 } 171 *p++ = c; 172 } 173 b->counter = (int)(p - dp->th_data); 174 } 175 176 /* Update count associated with the buffer, get new buffer 177 from the queue. Calls write_behind only if next buffer not 178 available. 179 */ 180 int 181 writeit(FILE *file, struct tftphdr **dpp, int ct, int convert) 182 { 183 bfs[current].counter = ct; /* set size of data to write */ 184 current = !current; /* switch to other buffer */ 185 if (bfs[current].counter != BF_FREE) /* if not free */ 186 (void)write_behind(file, convert); /* flush it */ 187 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 188 *dpp = (struct tftphdr *)bfs[current].buf; 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) return -1; /* nak logic? */ 220 221 if (convert == 0) 222 return write(fileno(file), buf, count); 223 224 p = buf; 225 ct = count; 226 while (ct--) { /* loop over the buffer */ 227 c = *p++; /* pick up a character */ 228 if (prevchar == '\r') { /* if prev char was cr */ 229 if (c == '\n') /* if have cr,lf then just */ 230 fseek(file, -1, 1); /* smash lf on top of the cr */ 231 else 232 if (c == '\0') /* if have cr,nul then */ 233 goto skipit; /* just skip over the putc */ 234 /* else just fall through and allow it */ 235 } 236 putc(c, file); 237 skipit: 238 prevchar = c; 239 } 240 return count; 241 } 242 243 244 /* When an error has occurred, it is possible that the two sides 245 * are out of synch. Ie: that what I think is the other side's 246 * response to packet N is really their response to packet N-1. 247 * 248 * So, to try to prevent that, we flush all the input queued up 249 * for us on the network connection on our host. 250 * 251 * We return the number of packets we flushed (mostly for reporting 252 * when trace is active). 253 */ 254 255 int 256 synchnet(int f) 257 { 258 int i, j = 0; 259 char rbuf[PKTSIZE]; 260 struct sockaddr_in from; 261 socklen_t fromlen; 262 263 while (1) { 264 (void) ioctl(f, FIONREAD, &i); 265 if (i) { 266 j++; 267 fromlen = sizeof from; 268 (void) recvfrom(f, rbuf, sizeof (rbuf), 0, 269 (struct sockaddr *)&from, &fromlen); 270 } else { 271 return(j); 272 } 273 } 274 } 275