1 /* 2 * Copyright (c) 1985 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #ifndef lint 8 static char sccsid[] = "@(#)tftpsubs.c 5.2 (Berkeley) 02/07/86"; 9 #endif not lint 10 11 /* Simple minded read-ahead/write-behind subroutines for tftp user and 12 server. Written originally with multiple buffers in mind, but current 13 implementation has two buffer logic wired in. 14 15 Todo: add some sort of final error check so when the write-buffer 16 is finally flushed, the caller can detect if the disk filled up 17 (or had an i/o error) and return a nak to the other side. 18 19 Jim Guyton 10/85 20 */ 21 22 #include <sys/types.h> 23 #include <sys/socket.h> 24 #include <sys/ioctl.h> 25 #include <netinet/in.h> 26 #include <arpa/tftp.h> 27 #include <stdio.h> 28 29 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */ 30 31 struct bf { 32 int counter; /* size of data in buffer, or flag */ 33 char buf[PKTSIZE]; /* room for data packet */ 34 } bfs[2]; 35 36 /* Values for bf.counter */ 37 #define BF_ALLOC -3 /* alloc'd but not yet filled */ 38 #define BF_FREE -2 /* free */ 39 /* [-1 .. SEGSIZE] = size of data in the data buffer */ 40 41 static int nextone; /* index of next buffer to use */ 42 static int current; /* index of buffer in use */ 43 44 /* control flags for crlf conversions */ 45 int newline = 0; /* fillbuf: in middle of newline expansion */ 46 int prevchar = -1; /* putbuf: previous char (cr check) */ 47 48 struct tftphdr *rw_init(); 49 50 struct tftphdr *w_init() { return rw_init(0); } /* write-behind */ 51 struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */ 52 53 struct tftphdr * 54 rw_init(x) /* init for either read-ahead or write-behind */ 55 int x; /* zero for write-behind, one for read-head */ 56 { 57 newline = 0; /* init crlf flag */ 58 prevchar = -1; 59 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 60 current = 0; 61 bfs[1].counter = BF_FREE; 62 nextone = x; /* ahead or behind? */ 63 return (struct tftphdr *)bfs[0].buf; 64 } 65 66 67 /* Have emptied current buffer by sending to net and getting ack. 68 Free it and return next buffer filled with data. 69 */ 70 readit(file, dpp, convert) 71 FILE *file; /* file opened for read */ 72 struct tftphdr **dpp; 73 int convert; /* if true, convert to ascii */ 74 { 75 struct bf *b; 76 77 bfs[current].counter = BF_FREE; /* free old one */ 78 current = !current; /* "incr" current */ 79 80 b = &bfs[current]; /* look at new buffer */ 81 if (b->counter == BF_FREE) /* if it's empty */ 82 read_ahead(file, convert); /* fill it */ 83 /* assert(b->counter != BF_FREE); /* check */ 84 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 85 return b->counter; 86 } 87 88 /* 89 * fill the input buffer, doing ascii conversions if requested 90 * conversions are lf -> cr,lf and cr -> cr, nul 91 */ 92 read_ahead(file, convert) 93 FILE *file; /* file opened for read */ 94 int convert; /* if true, convert to ascii */ 95 { 96 register int i; 97 register char *p; 98 register int c; 99 struct bf *b; 100 struct tftphdr *dp; 101 102 b = &bfs[nextone]; /* look at "next" buffer */ 103 if (b->counter != BF_FREE) /* nop if not free */ 104 return; 105 nextone = !nextone; /* "incr" next buffer ptr */ 106 107 dp = (struct tftphdr *)b->buf; 108 109 if (convert == 0) { 110 b->counter = read(fileno(file), dp->th_data, SEGSIZE); 111 return; 112 } 113 114 p = dp->th_data; 115 for (i = 0 ; i < SEGSIZE; i++) { 116 if (newline) { 117 if (prevchar == '\n') 118 c = '\n'; /* lf to cr,lf */ 119 else c = '\0'; /* cr to cr,nul */ 120 newline = 0; 121 } 122 else { 123 c = getc(file); 124 if (c == EOF) break; 125 if (c == '\n' || c == '\r') { 126 prevchar = c; 127 c = '\r'; 128 newline = 1; 129 } 130 } 131 *p++ = c; 132 } 133 b->counter = (int)(p - dp->th_data); 134 } 135 136 /* Update count associated with the buffer, get new buffer 137 from the queue. Calls write_behind only if next buffer not 138 available. 139 */ 140 writeit(file, dpp, ct, convert) 141 FILE *file; 142 struct tftphdr **dpp; 143 int convert; 144 { 145 bfs[current].counter = ct; /* set size of data to write */ 146 current = !current; /* switch to other buffer */ 147 if (bfs[current].counter != BF_FREE) /* if not free */ 148 write_behind(file, convert); /* flush it */ 149 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 150 *dpp = (struct tftphdr *)bfs[current].buf; 151 return ct; /* this is a lie of course */ 152 } 153 154 /* 155 * Output a buffer to a file, converting from netascii if requested. 156 * CR,NUL -> CR and CR,LF => LF. 157 * Note spec is undefined if we get CR as last byte of file or a 158 * CR followed by anything else. In this case we leave it alone. 159 */ 160 write_behind(file, convert) 161 FILE *file; 162 int convert; 163 { 164 char *buf; 165 int count; 166 register int ct; 167 register char *p; 168 register int c; /* current character */ 169 struct bf *b; 170 struct tftphdr *dp; 171 172 b = &bfs[nextone]; 173 if (b->counter < -1) /* anything to flush? */ 174 return 0; /* just nop if nothing to do */ 175 176 count = b->counter; /* remember byte count */ 177 b->counter = BF_FREE; /* reset flag */ 178 dp = (struct tftphdr *)b->buf; 179 nextone = !nextone; /* incr for next time */ 180 buf = dp->th_data; 181 182 if (count <= 0) return -1; /* nak logic? */ 183 184 if (convert == 0) 185 return write(fileno(file), buf, count); 186 187 p = buf; 188 ct = count; 189 while (ct--) { /* loop over the buffer */ 190 c = *p++; /* pick up a character */ 191 if (prevchar == '\r') { /* if prev char was cr */ 192 if (c == '\n') /* if have cr,lf then just */ 193 fseek(file, -1, 1); /* smash lf on top of the cr */ 194 else 195 if (c == '\0') /* if have cr,nul then */ 196 goto skipit; /* just skip over the putc */ 197 /* else just fall through and allow it */ 198 } 199 putc(c, file); 200 skipit: 201 prevchar = c; 202 } 203 return count; 204 } 205 206 207 /* When an error has occurred, it is possible that the two sides 208 * are out of synch. Ie: that what I think is the other side's 209 * response to packet N is really their response to packet N-1. 210 * 211 * So, to try to prevent that, we flush all the input queued up 212 * for us on the network connection on our host. 213 * 214 * We return the number of packets we flushed (mostly for reporting 215 * when trace is active). 216 */ 217 218 int 219 synchnet(f) 220 int f; /* socket to flush */ 221 { 222 int i, j = 0; 223 char rbuf[PKTSIZE]; 224 struct sockaddr_in from; 225 int fromlen; 226 227 while (1) { 228 (void) ioctl(f, FIONREAD, &i); 229 if (i) { 230 j++; 231 fromlen = sizeof from; 232 (void) recvfrom(f, rbuf, sizeof (rbuf), 0, 233 (caddr_t)&from, &fromlen); 234 } else { 235 return(j); 236 } 237 } 238 } 239