tftp.c

unix下tftp服务器源码

/* $Id: tftp.c,v 1.17 2004/01/08 20:47:00 hpa Exp $ */

/* $OpenBSD: tftp.c,v 1.4 1997/08/06 06:43:45 deraadt Exp $	*/
/* $NetBSD: tftp.c,v 1.5 1995/04/29 05:55:25 cgd Exp $	*/

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "tftpsubs.h"

#ifndef lint
/* static char sccsid[] = "@(#)tftp.c	8.1 (Berkeley) 6/6/93"; */
/* static char rcsid[] = "$OpenBSD: tftp.c,v 1.4 1997/08/06 06:43:45 deraadt Exp $"; */
static const char *rcsid UNUSED =
"tftp-hpa $Id: tftp.c,v 1.17 2004/01/08 20:47:00 hpa Exp $";
#endif /* not lint */

/* Many bug fixes are from Jim Guyton <guyton@rand-unix> */

/*
 * TFTP User Program -- Protocol Machines
 */
#include "extern.h"

extern  struct sockaddr_in peeraddr;	/* filled in by main */
extern  int     f;			/* the opened socket */
extern  int     trace;
extern  int     verbose;
extern  int     rexmtval;
extern  int     maxtimeout;

#define PKTSIZE    SEGSIZE+4
char    ackbuf[PKTSIZE];
int	timeout;
sigjmp_buf	toplevel;
sigjmp_buf	timeoutbuf;

static void nak(int, const char *);
static int makerequest(int, const char *, struct tftphdr *, const char *);
static void printstats(const char *, unsigned long);
static void startclock(void);
static void stopclock(void);
static void timer(int);
static void tpacket(const char *, struct tftphdr *, int);

/*
 * Send the requested file.
 */
void
tftp_sendfile(int fd, const char *name, const char *mode)
{
	struct tftphdr *ap;	   /* data and ack packets */
	struct tftphdr *dp;
	int n;
	volatile int is_request;
	volatile u_short block;
	volatile int size, convert;
	volatile off_t amount;
	struct sockaddr_in from;
	int fromlen;
	FILE *file;
	u_short ap_opcode, ap_block;

	startclock();		/* start stat's clock */
	dp = r_init();		/* reset fillbuf/read-ahead code */
	ap = (struct tftphdr *)ackbuf;
	convert = !strcmp(mode, "netascii");
	file = fdopen(fd, convert ? "rt" : "rb");
	block = 0;
	is_request = 1;		/* First packet is the actual WRQ */
	amount = 0;

	bsd_signal(SIGALRM, timer);
	do {
		if (is_request) {
			size = makerequest(WRQ, name, dp, mode) - 4;
		} else {
		/*	size = read(fd, dp->th_data, SEGSIZE);	 */
			size = readit(file, &dp, convert);
			if (size < 0) {
				nak(errno + 100, NULL);
				break;
			}
			dp->th_opcode = htons((u_short)DATA);
			dp->th_block = htons((u_short)block);
		}
		timeout = 0;
		(void) sigsetjmp(timeoutbuf,1);

		if (trace)
			tpacket("sent", dp, size + 4);
		n = sendto(f, dp, size + 4, 0,
		    (struct sockaddr *)&peeraddr, sizeof(peeraddr));
		if (n != size + 4) {
			perror("tftp: sendto");
			goto abort;
		}
		read_ahead(file, convert);
		for ( ; ; ) {
			alarm(rexmtval);
			do {
				fromlen = sizeof(from);
				n = recvfrom(f, ackbuf, sizeof(ackbuf), 0,
				    (struct sockaddr *)&from, &fromlen);
			} while (n <= 0);
			alarm(0);
			if (n < 0) {
				perror("tftp: recvfrom");
				goto abort;
			}
			peeraddr.sin_port = from.sin_port;	/* added */
			if (trace)
				tpacket("received", ap, n);
			/* should verify packet came from server */
			ap_opcode = ntohs((u_short)ap->th_opcode);
			ap_block = ntohs((u_short)ap->th_block);
			if (ap_opcode == ERROR) {
				printf("Error code %d: %s\n", ap_block,
					ap->th_msg);
				goto abort;
			}
			if (ap_opcode == ACK) {
				int j;

				if (ap_block == block) {
					break;
				}
				/* On an error, try to synchronize
				 * both sides.
				 */
				j = synchnet(f);
				if (j && trace) {
					printf("discarded %d packets\n",
							j);
				}
				/*
				 * RFC1129/RFC1350: We MUST NOT re-send the DATA
				 * packet in response to an invalid ACK.  Doing so
				 * would cause the Sorcerer's Apprentice bug.
				 */
			}
		}
		if ( !is_request )
			amount += size;
		is_request = 0;
		block++;
	} while (size == SEGSIZE || block == 1);
abort:
	fclose(file);
	stopclock();
	if (amount > 0)
		printstats("Sent", amount);
}

/*
 * Receive a file.
 */
void
tftp_recvfile(int fd, const char *name, const char *mode)
{
	struct tftphdr *ap;
	struct tftphdr *dp;
	int n;
	volatile u_short block;
	volatile int size, firsttrip;
	volatile unsigned long amount;
	struct sockaddr_in from;
	int fromlen;
	FILE *file;
	volatile int convert;		/* true if converting crlf -> lf */
	u_short dp_opcode, dp_block;

	startclock();
	dp = w_init();
	ap = (struct tftphdr *)ackbuf;
	convert = !strcmp(mode, "netascii");
	file = fdopen(fd, convert ?"wt":"wb");
	block = 1;
	firsttrip = 1;
	amount = 0;

	bsd_signal(SIGALRM, timer);
	do {
		if (firsttrip) {
			size = makerequest(RRQ, name, ap, mode);
			firsttrip = 0;
		} else {
			ap->th_opcode = htons((u_short)ACK);
			ap->th_block = htons((u_short)block);
			size = 4;
			block++;
		}
		timeout = 0;
		(void) sigsetjmp(timeoutbuf,1);
send_ack:
		if (trace)
			tpacket("sent", ap, size);
		if (sendto(f, ackbuf, size, 0, (struct sockaddr *)&peeraddr,
		    sizeof(peeraddr)) != size) {
			alarm(0);
			perror("tftp: sendto");
			goto abort;
		}
		write_behind(file, convert);
		for ( ; ; ) {
			alarm(rexmtval);
			do  {
				fromlen = sizeof(from);
				n = recvfrom(f, dp, PKTSIZE, 0,
				    (struct sockaddr *)&from, &fromlen);
			} while (n <= 0);
			alarm(0);
			if (n < 0) {
				perror("tftp: recvfrom");
				goto abort;
			}
			peeraddr.sin_port = from.sin_port;	/* added */
			if (trace)
				tpacket("received", dp, n);
			/* should verify client address */
			dp_opcode = ntohs((u_short)dp->th_opcode);
			dp_block = ntohs((u_short)dp->th_block);
			if (dp_opcode == ERROR) {
			  printf("Error code %d: %s\n", dp_block, dp->th_msg);
			  goto abort;
			}
			if (dp_opcode == DATA) {
				int j;

				if (dp_block == block) {
					break;		/* have next packet */
				}
				/* On an error, try to synchronize
				 * both sides.
				 */
				j = synchnet(f);
				if (j && trace) {
					printf("discarded %d packets\n", j);
				}
				if (dp_block == (block-1)) {
					goto send_ack;	/* resend ack */
				}
			}
		}
	/*	size = write(fd, dp->th_data, n - 4); */
		size = writeit(file, &dp, n - 4, convert);
		if (size < 0) {
			nak(errno + 100, NULL);
			break;
		}
		amount += size;
	} while (size == SEGSIZE);
abort:						/* ok to ack, since user */
	ap->th_opcode = htons((u_short)ACK);	/* has seen err msg */
	ap->th_block = htons((u_short)block);
	(void) sendto(f, ackbuf, 4, 0, (struct sockaddr *)&peeraddr,
	    sizeof(peeraddr));
	write_behind(file, convert);		/* flush last buffer */
	fclose(file);
	stopclock();
	if (amount > 0)
		printstats("Received", amount);
}

static int
makerequest(int request, const char *name,
	    struct tftphdr *tp, const char *mode)
{
	char *cp;

	tp->th_opcode = htons((u_short)request);
	cp = (char *) &(tp->th_stuff);
	strcpy(cp, name);
	cp += strlen(name);
	*cp++ = '\0';
	strcpy(cp, mode);
	cp += strlen(mode);
	*cp++ = '\0';
	return (cp - (char *)tp);
}

static const char * const errmsgs[] =
{
  "Undefined error code", 			/* 0 - EUNDEF */
  "File not found",				/* 1 - ENOTFOUND */
  "Access denied",				/* 2 - EACCESS */
  "Disk full or allocation exceeded", 		/* 3 - ENOSPACE */
  "Illegal TFTP operation",			/* 4 - EBADOP */
  "Unknown transfer ID",			/* 5 - EBADID */
  "File already exists",			/* 6 - EEXISTS */
  "No such user",				/* 7 - ENOUSER */
  "Failure to negotiate RFC2347 options" 	/* 8 - EOPTNEG */
};
#define ERR_CNT (sizeof(errmsgs)/sizeof(const char *))

/*
 * Send a nak packet (error message).
 * Error code passed in is one of the
 * standard TFTP codes, or a UNIX errno
 * offset by 100.
 */
static void
nak(int error, const char *msg)
{
  struct tftphdr *tp;
  int length;
  
  tp = (struct tftphdr *)ackbuf;
  tp->th_opcode = htons((u_short)ERROR);
  tp->th_code = htons((u_short)error);

  if ( error >= 100 ) {
    /* This is a Unix errno+100 */
    if ( !msg )
      msg = strerror(error - 100);
    error = EUNDEF;
  } else {
    if ( (unsigned)error >= ERR_CNT )
      error = EUNDEF;
    
    if ( !msg )
      msg = errmsgs[error];
  }

  tp->th_code = htons((u_short)error);

  length = strlen(msg)+1;
  memcpy(tp->th_msg, msg, length);
  length += 4;			/* Add space for header */

  if (trace)
    tpacket("sent", tp, length);
  if (sendto(f, ackbuf, length, 0, (struct sockaddr *)&peeraddr,
	     sizeof(peeraddr)) != length)
    perror("nak");
}

static void
tpacket(const char *s, struct tftphdr *tp, int n)
{
	static const char *opcodes[] =
	   { "#0", "RRQ", "WRQ", "DATA", "ACK", "ERROR", "OACK" };
	char *cp, *file;
	u_short op = ntohs((u_short)tp->th_opcode);

	if (op < RRQ || op > ERROR)
		printf("%s opcode=%x ", s, op);
	else
		printf("%s %s ", s, opcodes[op]);
	switch (op) {

	case RRQ:
	case WRQ:
		n -= 2;
		file = cp = (char *) &(tp->th_stuff);
		cp = strchr(cp, '\0');
		printf("<file=%s, mode=%s>\n", file, cp + 1);
		break;

	case DATA:
		printf("<block=%d, %d bytes>\n", ntohs(tp->th_block), n - 4);
		break;

	case ACK:
		printf("<block=%d>\n", ntohs(tp->th_block));
		break;

	case ERROR:
		printf("<code=%d, msg=%s>\n", ntohs(tp->th_code), tp->th_msg);
		break;
	}
}

struct timeval tstart;
struct timeval tstop;

static void
startclock(void)
{
	(void)gettimeofday(&tstart, NULL);
}

static void
stopclock(void)
{

	(void)gettimeofday(&tstop, NULL);
}

static void
printstats(const char *direction, unsigned long amount)
{
	double delta;

	delta = (tstop.tv_sec+(tstop.tv_usec/100000.0)) -
		(tstart.tv_sec+(tstart.tv_usec/100000.0));
	if (verbose) {
	  printf("%s %lu bytes in %.1f seconds", direction, amount, delta);
	  printf(" [%.0f bit/s]", (amount*8.)/delta);
	  putchar('\n');
	}
}

static void
timer(int sig)
{
	int save_errno = errno;

	(void)sig;		/* Shut up unused warning */

	timeout += rexmtval;
	if (timeout >= maxtimeout) {
		printf("Transfer timed out.\n");
		errno = save_errno;
		siglongjmp(toplevel, -1);
	}
	errno = save_errno;
	siglongjmp(timeoutbuf, 1);
}