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 this notice is preserved and that due credit is given 7 * to the University of California at Berkeley. The name of the University 8 * may not be used to endorse or promote products derived from this 9 * software without specific prior written permission. This software 10 * is provided ``as is'' without express or implied warranty. 11 */ 12 13 #ifndef lint 14 static char sccsid[] = "@(#)tftpsubs.c 5.3 (Berkeley) 03/28/88"; 15 #endif /* not lint */ 16 17 /* Simple minded read-ahead/write-behind subroutines for tftp user and 18 server. Written originally with multiple buffers in mind, but current 19 implementation has two buffer logic wired in. 20 21 Todo: add some sort of final error check so when the write-buffer 22 is finally flushed, the caller can detect if the disk filled up 23 (or had an i/o error) and return a nak to the other side. 24 25 Jim Guyton 10/85 26 */ 27 28 #include <sys/types.h> 29 #include <sys/socket.h> 30 #include <sys/ioctl.h> 31 #include <netinet/in.h> 32 #include <arpa/tftp.h> 33 #include <stdio.h> 34 35 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */ 36 37 struct bf { 38 int counter; /* size of data in buffer, or flag */ 39 char buf[PKTSIZE]; /* room for data packet */ 40 } bfs[2]; 41 42 /* Values for bf.counter */ 43 #define BF_ALLOC -3 /* alloc'd but not yet filled */ 44 #define BF_FREE -2 /* free */ 45 /* [-1 .. SEGSIZE] = size of data in the data buffer */ 46 47 static int nextone; /* index of next buffer to use */ 48 static int current; /* index of buffer in use */ 49 50 /* control flags for crlf conversions */ 51 int newline = 0; /* fillbuf: in middle of newline expansion */ 52 int prevchar = -1; /* putbuf: previous char (cr check) */ 53 54 struct tftphdr *rw_init(); 55 56 struct tftphdr *w_init() { return rw_init(0); } /* write-behind */ 57 struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */ 58 59 struct tftphdr * 60 rw_init(x) /* init for either read-ahead or write-behind */ 61 int x; /* zero for write-behind, one for read-head */ 62 { 63 newline = 0; /* init crlf flag */ 64 prevchar = -1; 65 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 66 current = 0; 67 bfs[1].counter = BF_FREE; 68 nextone = x; /* ahead or behind? */ 69 return (struct tftphdr *)bfs[0].buf; 70 } 71 72 73 /* Have emptied current buffer by sending to net and getting ack. 74 Free it and return next buffer filled with data. 75 */ 76 readit(file, dpp, convert) 77 FILE *file; /* file opened for read */ 78 struct tftphdr **dpp; 79 int convert; /* if true, convert to ascii */ 80 { 81 struct bf *b; 82 83 bfs[current].counter = BF_FREE; /* free old one */ 84 current = !current; /* "incr" current */ 85 86 b = &bfs[current]; /* look at new buffer */ 87 if (b->counter == BF_FREE) /* if it's empty */ 88 read_ahead(file, convert); /* fill it */ 89 /* assert(b->counter != BF_FREE); /* check */ 90 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 91 return b->counter; 92 } 93 94 /* 95 * fill the input buffer, doing ascii conversions if requested 96 * conversions are lf -> cr,lf and cr -> cr, nul 97 */ 98 read_ahead(file, convert) 99 FILE *file; /* file opened for read */ 100 int convert; /* if true, convert to ascii */ 101 { 102 register int i; 103 register char *p; 104 register int c; 105 struct bf *b; 106 struct tftphdr *dp; 107 108 b = &bfs[nextone]; /* look at "next" buffer */ 109 if (b->counter != BF_FREE) /* nop if not free */ 110 return; 111 nextone = !nextone; /* "incr" next buffer ptr */ 112 113 dp = (struct tftphdr *)b->buf; 114 115 if (convert == 0) { 116 b->counter = read(fileno(file), dp->th_data, SEGSIZE); 117 return; 118 } 119 120 p = dp->th_data; 121 for (i = 0 ; i < SEGSIZE; i++) { 122 if (newline) { 123 if (prevchar == '\n') 124 c = '\n'; /* lf to cr,lf */ 125 else c = '\0'; /* cr to cr,nul */ 126 newline = 0; 127 } 128 else { 129 c = getc(file); 130 if (c == EOF) break; 131 if (c == '\n' || c == '\r') { 132 prevchar = c; 133 c = '\r'; 134 newline = 1; 135 } 136 } 137 *p++ = c; 138 } 139 b->counter = (int)(p - dp->th_data); 140 } 141 142 /* Update count associated with the buffer, get new buffer 143 from the queue. Calls write_behind only if next buffer not 144 available. 145 */ 146 writeit(file, dpp, ct, convert) 147 FILE *file; 148 struct tftphdr **dpp; 149 int convert; 150 { 151 bfs[current].counter = ct; /* set size of data to write */ 152 current = !current; /* switch to other buffer */ 153 if (bfs[current].counter != BF_FREE) /* if not free */ 154 write_behind(file, convert); /* flush it */ 155 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 156 *dpp = (struct tftphdr *)bfs[current].buf; 157 return ct; /* this is a lie of course */ 158 } 159 160 /* 161 * Output a buffer to a file, converting from netascii if requested. 162 * CR,NUL -> CR and CR,LF => LF. 163 * Note spec is undefined if we get CR as last byte of file or a 164 * CR followed by anything else. In this case we leave it alone. 165 */ 166 write_behind(file, convert) 167 FILE *file; 168 int convert; 169 { 170 char *buf; 171 int count; 172 register int ct; 173 register char *p; 174 register int c; /* current character */ 175 struct bf *b; 176 struct tftphdr *dp; 177 178 b = &bfs[nextone]; 179 if (b->counter < -1) /* anything to flush? */ 180 return 0; /* just nop if nothing to do */ 181 182 count = b->counter; /* remember byte count */ 183 b->counter = BF_FREE; /* reset flag */ 184 dp = (struct tftphdr *)b->buf; 185 nextone = !nextone; /* incr for next time */ 186 buf = dp->th_data; 187 188 if (count <= 0) return -1; /* nak logic? */ 189 190 if (convert == 0) 191 return write(fileno(file), buf, count); 192 193 p = buf; 194 ct = count; 195 while (ct--) { /* loop over the buffer */ 196 c = *p++; /* pick up a character */ 197 if (prevchar == '\r') { /* if prev char was cr */ 198 if (c == '\n') /* if have cr,lf then just */ 199 fseek(file, -1, 1); /* smash lf on top of the cr */ 200 else 201 if (c == '\0') /* if have cr,nul then */ 202 goto skipit; /* just skip over the putc */ 203 /* else just fall through and allow it */ 204 } 205 putc(c, file); 206 skipit: 207 prevchar = c; 208 } 209 return count; 210 } 211 212 213 /* When an error has occurred, it is possible that the two sides 214 * are out of synch. Ie: that what I think is the other side's 215 * response to packet N is really their response to packet N-1. 216 * 217 * So, to try to prevent that, we flush all the input queued up 218 * for us on the network connection on our host. 219 * 220 * We return the number of packets we flushed (mostly for reporting 221 * when trace is active). 222 */ 223 224 int 225 synchnet(f) 226 int f; /* socket to flush */ 227 { 228 int i, j = 0; 229 char rbuf[PKTSIZE]; 230 struct sockaddr_in from; 231 int fromlen; 232 233 while (1) { 234 (void) ioctl(f, FIONREAD, &i); 235 if (i) { 236 j++; 237 fromlen = sizeof from; 238 (void) recvfrom(f, rbuf, sizeof (rbuf), 0, 239 (caddr_t)&from, &fromlen); 240 } else { 241 return(j); 242 } 243 } 244 } 245