1 /*
2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char sccsid[] = "@(#)tftpsubs.c 8.1 (Berkeley) 06/06/93";
10 #endif /* not lint */
11
12 /* Simple minded read-ahead/write-behind subroutines for tftp user and
13 server. Written originally with multiple buffers in mind, but current
14 implementation has two buffer logic wired in.
15
16 Todo: add some sort of final error check so when the write-buffer
17 is finally flushed, the caller can detect if the disk filled up
18 (or had an i/o error) and return a nak to the other side.
19
20 Jim Guyton 10/85
21 */
22
23 #include <sys/types.h>
24 #include <sys/socket.h>
25 #include <sys/ioctl.h>
26 #include <netinet/in.h>
27 #include <arpa/tftp.h>
28
29 #include <stdio.h>
30 #include <unistd.h>
31
32 #include "tftpsubs.h"
33
34 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */
35
36 struct bf {
37 int counter; /* size of data in buffer, or flag */
38 char buf[PKTSIZE]; /* room for data packet */
39 } bfs[2];
40
41 /* Values for bf.counter */
42 #define BF_ALLOC -3 /* alloc'd but not yet filled */
43 #define BF_FREE -2 /* free */
44 /* [-1 .. SEGSIZE] = size of data in the data buffer */
45
46 static int nextone; /* index of next buffer to use */
47 static int current; /* index of buffer in use */
48
49 /* control flags for crlf conversions */
50 int newline = 0; /* fillbuf: in middle of newline expansion */
51 int prevchar = -1; /* putbuf: previous char (cr check) */
52
53 static struct tftphdr *rw_init();
54
w_init()55 struct tftphdr *w_init() { return rw_init(0); } /* write-behind */
r_init()56 struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */
57
58 static struct tftphdr *
rw_init(x)59 rw_init(x) /* init for either read-ahead or write-behind */
60 int x; /* zero for write-behind, one for read-head */
61 {
62 newline = 0; /* init crlf flag */
63 prevchar = -1;
64 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */
65 current = 0;
66 bfs[1].counter = BF_FREE;
67 nextone = x; /* ahead or behind? */
68 return (struct tftphdr *)bfs[0].buf;
69 }
70
71
72 /* Have emptied current buffer by sending to net and getting ack.
73 Free it and return next buffer filled with data.
74 */
75 int
readit(file,dpp,convert)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 void
read_ahead(file,convert)99 read_ahead(file, convert)
100 FILE *file; /* file opened for read */
101 int convert; /* if true, convert to ascii */
102 {
103 register int i;
104 register char *p;
105 register int c;
106 struct bf *b;
107 struct tftphdr *dp;
108
109 b = &bfs[nextone]; /* look at "next" buffer */
110 if (b->counter != BF_FREE) /* nop if not free */
111 return;
112 nextone = !nextone; /* "incr" next buffer ptr */
113
114 dp = (struct tftphdr *)b->buf;
115
116 if (convert == 0) {
117 b->counter = read(fileno(file), dp->th_data, SEGSIZE);
118 return;
119 }
120
121 p = dp->th_data;
122 for (i = 0 ; i < SEGSIZE; i++) {
123 if (newline) {
124 if (prevchar == '\n')
125 c = '\n'; /* lf to cr,lf */
126 else c = '\0'; /* cr to cr,nul */
127 newline = 0;
128 }
129 else {
130 c = getc(file);
131 if (c == EOF) break;
132 if (c == '\n' || c == '\r') {
133 prevchar = c;
134 c = '\r';
135 newline = 1;
136 }
137 }
138 *p++ = c;
139 }
140 b->counter = (int)(p - dp->th_data);
141 }
142
143 /* Update count associated with the buffer, get new buffer
144 from the queue. Calls write_behind only if next buffer not
145 available.
146 */
147 int
writeit(file,dpp,ct,convert)148 writeit(file, dpp, ct, convert)
149 FILE *file;
150 struct tftphdr **dpp;
151 int ct, convert;
152 {
153 bfs[current].counter = ct; /* set size of data to write */
154 current = !current; /* switch to other buffer */
155 if (bfs[current].counter != BF_FREE) /* if not free */
156 (void)write_behind(file, convert); /* flush it */
157 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */
158 *dpp = (struct tftphdr *)bfs[current].buf;
159 return ct; /* this is a lie of course */
160 }
161
162 /*
163 * Output a buffer to a file, converting from netascii if requested.
164 * CR,NUL -> CR and CR,LF => LF.
165 * Note spec is undefined if we get CR as last byte of file or a
166 * CR followed by anything else. In this case we leave it alone.
167 */
168 int
write_behind(file,convert)169 write_behind(file, convert)
170 FILE *file;
171 int convert;
172 {
173 char *buf;
174 int count;
175 register int ct;
176 register char *p;
177 register int c; /* current character */
178 struct bf *b;
179 struct tftphdr *dp;
180
181 b = &bfs[nextone];
182 if (b->counter < -1) /* anything to flush? */
183 return 0; /* just nop if nothing to do */
184
185 count = b->counter; /* remember byte count */
186 b->counter = BF_FREE; /* reset flag */
187 dp = (struct tftphdr *)b->buf;
188 nextone = !nextone; /* incr for next time */
189 buf = dp->th_data;
190
191 if (count <= 0) return -1; /* nak logic? */
192
193 if (convert == 0)
194 return write(fileno(file), buf, count);
195
196 p = buf;
197 ct = count;
198 while (ct--) { /* loop over the buffer */
199 c = *p++; /* pick up a character */
200 if (prevchar == '\r') { /* if prev char was cr */
201 if (c == '\n') /* if have cr,lf then just */
202 fseek(file, -1, 1); /* smash lf on top of the cr */
203 else
204 if (c == '\0') /* if have cr,nul then */
205 goto skipit; /* just skip over the putc */
206 /* else just fall through and allow it */
207 }
208 putc(c, file);
209 skipit:
210 prevchar = c;
211 }
212 return count;
213 }
214
215
216 /* When an error has occurred, it is possible that the two sides
217 * are out of synch. Ie: that what I think is the other side's
218 * response to packet N is really their response to packet N-1.
219 *
220 * So, to try to prevent that, we flush all the input queued up
221 * for us on the network connection on our host.
222 *
223 * We return the number of packets we flushed (mostly for reporting
224 * when trace is active).
225 */
226
227 int
synchnet(f)228 synchnet(f)
229 int f; /* socket to flush */
230 {
231 int i, j = 0;
232 char rbuf[PKTSIZE];
233 struct sockaddr_in from;
234 int fromlen;
235
236 while (1) {
237 (void) ioctl(f, FIONREAD, &i);
238 if (i) {
239 j++;
240 fromlen = sizeof from;
241 (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
242 (struct sockaddr *)&from, &fromlen);
243 } else {
244 return(j);
245 }
246 }
247 }
248