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Annotation of 43BSDReno/usr.bin/tftp/tftpsubs.c, revision 1.1

1.1     ! root        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: (1) source distributions retain this entire copyright
        !             7:  * notice and comment, and (2) distributions including binaries display
        !             8:  * the following acknowledgement:  ``This product includes software
        !             9:  * developed by the University of California, Berkeley and its contributors''
        !            10:  * in the documentation or other materials provided with the distribution
        !            11:  * and in all advertising materials mentioning features or use of this
        !            12:  * software. Neither the name of the University nor the names of its
        !            13:  * contributors may be used to endorse or promote products derived
        !            14:  * from this software without specific prior written permission.
        !            15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            18:  */
        !            19: 
        !            20: #ifndef lint
        !            21: static char sccsid[] = "@(#)tftpsubs.c 5.5 (Berkeley) 6/1/90";
        !            22: #endif /* not lint */
        !            23: 
        !            24: /* Simple minded read-ahead/write-behind subroutines for tftp user and
        !            25:    server.  Written originally with multiple buffers in mind, but current
        !            26:    implementation has two buffer logic wired in.
        !            27: 
        !            28:    Todo:  add some sort of final error check so when the write-buffer
        !            29:    is finally flushed, the caller can detect if the disk filled up
        !            30:    (or had an i/o error) and return a nak to the other side.
        !            31: 
        !            32:                        Jim Guyton 10/85
        !            33:  */
        !            34: 
        !            35: #include <sys/types.h>
        !            36: #include <sys/socket.h>
        !            37: #include <sys/ioctl.h>
        !            38: #include <netinet/in.h>
        !            39: #include <arpa/tftp.h>
        !            40: #include <stdio.h>
        !            41: 
        !            42: #define PKTSIZE SEGSIZE+4       /* should be moved to tftp.h */
        !            43: 
        !            44: struct bf {
        !            45:        int counter;            /* size of data in buffer, or flag */
        !            46:        char buf[PKTSIZE];      /* room for data packet */
        !            47: } bfs[2];
        !            48: 
        !            49:                                /* Values for bf.counter  */
        !            50: #define BF_ALLOC -3             /* alloc'd but not yet filled */
        !            51: #define BF_FREE  -2             /* free */
        !            52: /* [-1 .. SEGSIZE] = size of data in the data buffer */
        !            53: 
        !            54: static int nextone;     /* index of next buffer to use */
        !            55: static int current;     /* index of buffer in use */
        !            56: 
        !            57:                        /* control flags for crlf conversions */
        !            58: int newline = 0;        /* fillbuf: in middle of newline expansion */
        !            59: int prevchar = -1;      /* putbuf: previous char (cr check) */
        !            60: 
        !            61: struct tftphdr *rw_init();
        !            62: 
        !            63: struct tftphdr *w_init() { return rw_init(0); }         /* write-behind */
        !            64: struct tftphdr *r_init() { return rw_init(1); }         /* read-ahead */
        !            65: 
        !            66: struct tftphdr *
        !            67: rw_init(x)              /* init for either read-ahead or write-behind */
        !            68: int x;                  /* zero for write-behind, one for read-head */
        !            69: {
        !            70:        newline = 0;            /* init crlf flag */
        !            71:        prevchar = -1;
        !            72:        bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
        !            73:        current = 0;
        !            74:        bfs[1].counter = BF_FREE;
        !            75:        nextone = x;                    /* ahead or behind? */
        !            76:        return (struct tftphdr *)bfs[0].buf;
        !            77: }
        !            78: 
        !            79: 
        !            80: /* Have emptied current buffer by sending to net and getting ack.
        !            81:    Free it and return next buffer filled with data.
        !            82:  */
        !            83: readit(file, dpp, convert)
        !            84:        FILE *file;                     /* file opened for read */
        !            85:        struct tftphdr **dpp;
        !            86:        int convert;                    /* if true, convert to ascii */
        !            87: {
        !            88:        struct bf *b;
        !            89: 
        !            90:        bfs[current].counter = BF_FREE; /* free old one */
        !            91:        current = !current;             /* "incr" current */
        !            92: 
        !            93:        b = &bfs[current];              /* look at new buffer */
        !            94:        if (b->counter == BF_FREE)      /* if it's empty */
        !            95:                read_ahead(file, convert);      /* fill it */
        !            96: /*      assert(b->counter != BF_FREE);  /* check */
        !            97:        *dpp = (struct tftphdr *)b->buf;        /* set caller's ptr */
        !            98:        return b->counter;
        !            99: }
        !           100: 
        !           101: /*
        !           102:  * fill the input buffer, doing ascii conversions if requested
        !           103:  * conversions are  lf -> cr,lf  and cr -> cr, nul
        !           104:  */
        !           105: read_ahead(file, convert)
        !           106:        FILE *file;                     /* file opened for read */
        !           107:        int convert;                    /* if true, convert to ascii */
        !           108: {
        !           109:        register int i;
        !           110:        register char *p;
        !           111:        register int c;
        !           112:        struct bf *b;
        !           113:        struct tftphdr *dp;
        !           114: 
        !           115:        b = &bfs[nextone];              /* look at "next" buffer */
        !           116:        if (b->counter != BF_FREE)      /* nop if not free */
        !           117:                return;
        !           118:        nextone = !nextone;             /* "incr" next buffer ptr */
        !           119: 
        !           120:        dp = (struct tftphdr *)b->buf;
        !           121: 
        !           122:        if (convert == 0) {
        !           123:                b->counter = read(fileno(file), dp->th_data, SEGSIZE);
        !           124:                return;
        !           125:        }
        !           126: 
        !           127:        p = dp->th_data;
        !           128:        for (i = 0 ; i < SEGSIZE; i++) {
        !           129:                if (newline) {
        !           130:                        if (prevchar == '\n')
        !           131:                                c = '\n';       /* lf to cr,lf */
        !           132:                        else    c = '\0';       /* cr to cr,nul */
        !           133:                        newline = 0;
        !           134:                }
        !           135:                else {
        !           136:                        c = getc(file);
        !           137:                        if (c == EOF) break;
        !           138:                        if (c == '\n' || c == '\r') {
        !           139:                                prevchar = c;
        !           140:                                c = '\r';
        !           141:                                newline = 1;
        !           142:                        }
        !           143:                }
        !           144:               *p++ = c;
        !           145:        }
        !           146:        b->counter = (int)(p - dp->th_data);
        !           147: }
        !           148: 
        !           149: /* Update count associated with the buffer, get new buffer
        !           150:    from the queue.  Calls write_behind only if next buffer not
        !           151:    available.
        !           152:  */
        !           153: writeit(file, dpp, ct, convert)
        !           154:        FILE *file;
        !           155:        struct tftphdr **dpp;
        !           156:        int convert;
        !           157: {
        !           158:        bfs[current].counter = ct;      /* set size of data to write */
        !           159:        current = !current;             /* switch to other buffer */
        !           160:        if (bfs[current].counter != BF_FREE)     /* if not free */
        !           161:                write_behind(file, convert);     /* flush it */
        !           162:        bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
        !           163:        *dpp =  (struct tftphdr *)bfs[current].buf;
        !           164:        return ct;                      /* this is a lie of course */
        !           165: }
        !           166: 
        !           167: /*
        !           168:  * Output a buffer to a file, converting from netascii if requested.
        !           169:  * CR,NUL -> CR  and CR,LF => LF.
        !           170:  * Note spec is undefined if we get CR as last byte of file or a
        !           171:  * CR followed by anything else.  In this case we leave it alone.
        !           172:  */
        !           173: write_behind(file, convert)
        !           174:        FILE *file;
        !           175:        int convert;
        !           176: {
        !           177:        char *buf;
        !           178:        int count;
        !           179:        register int ct;
        !           180:        register char *p;
        !           181:        register int c;                 /* current character */
        !           182:        struct bf *b;
        !           183:        struct tftphdr *dp;
        !           184: 
        !           185:        b = &bfs[nextone];
        !           186:        if (b->counter < -1)            /* anything to flush? */
        !           187:                return 0;               /* just nop if nothing to do */
        !           188: 
        !           189:        count = b->counter;             /* remember byte count */
        !           190:        b->counter = BF_FREE;           /* reset flag */
        !           191:        dp = (struct tftphdr *)b->buf;
        !           192:        nextone = !nextone;             /* incr for next time */
        !           193:        buf = dp->th_data;
        !           194: 
        !           195:        if (count <= 0) return -1;      /* nak logic? */
        !           196: 
        !           197:        if (convert == 0)
        !           198:                return write(fileno(file), buf, count);
        !           199: 
        !           200:        p = buf;
        !           201:        ct = count;
        !           202:        while (ct--) {                  /* loop over the buffer */
        !           203:            c = *p++;                   /* pick up a character */
        !           204:            if (prevchar == '\r') {     /* if prev char was cr */
        !           205:                if (c == '\n')          /* if have cr,lf then just */
        !           206:                   fseek(file, -1, 1);  /* smash lf on top of the cr */
        !           207:                else
        !           208:                   if (c == '\0')       /* if have cr,nul then */
        !           209:                        goto skipit;    /* just skip over the putc */
        !           210:                /* else just fall through and allow it */
        !           211:            }
        !           212:            putc(c, file);
        !           213: skipit:
        !           214:            prevchar = c;
        !           215:        }
        !           216:        return count;
        !           217: }
        !           218: 
        !           219: 
        !           220: /* When an error has occurred, it is possible that the two sides
        !           221:  * are out of synch.  Ie: that what I think is the other side's
        !           222:  * response to packet N is really their response to packet N-1.
        !           223:  *
        !           224:  * So, to try to prevent that, we flush all the input queued up
        !           225:  * for us on the network connection on our host.
        !           226:  *
        !           227:  * We return the number of packets we flushed (mostly for reporting
        !           228:  * when trace is active).
        !           229:  */
        !           230: 
        !           231: int
        !           232: synchnet(f)
        !           233: int    f;              /* socket to flush */
        !           234: {
        !           235:        int i, j = 0;
        !           236:        char rbuf[PKTSIZE];
        !           237:        struct sockaddr_in from;
        !           238:        int fromlen;
        !           239: 
        !           240:        while (1) {
        !           241:                (void) ioctl(f, FIONREAD, &i);
        !           242:                if (i) {
        !           243:                        j++;
        !           244:                        fromlen = sizeof from;
        !           245:                        (void) recvfrom(f, rbuf, sizeof (rbuf), 0,
        !           246:                                (caddr_t)&from, &fromlen);
        !           247:                } else {
        !           248:                        return(j);
        !           249:                }
        !           250:        }
        !           251: }

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