print-tftp.c

/*
 * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
 *	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: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* \summary: Trivial File Transfer Protocol (TFTP) printer */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <netdissect-stdinc.h>

#include <string.h>

#include "netdissect.h"
#include "extract.h"

/*
 * Trivial File Transfer Protocol (IEN-133)
 */

/*
 * Packet types.
 */
#define	RRQ	01			/* read request */
#define	WRQ	02			/* write request */
#define	DATA	03			/* data packet */
#define	ACK	04			/* acknowledgement */
#define	TFTP_ERROR	05			/* error code */
#define OACK	06			/* option acknowledgement */

struct	tftphdr {
	unsigned short	th_opcode;		/* packet type */
	union {
		unsigned short	tu_block;	/* block # */
		unsigned short	tu_code;	/* error code */
		char	tu_stuff[1];	/* request packet stuff */
	} th_u;
	char	th_data[1];		/* data or error string */
};

#define	th_block	th_u.tu_block
#define	th_code		th_u.tu_code
#define	th_stuff	th_u.tu_stuff
#define	th_msg		th_data

/*
 * Error codes.
 */
#define	EUNDEF		0		/* not defined */
#define	ENOTFOUND	1		/* file not found */
#define	EACCESS		2		/* access violation */
#define	ENOSPACE	3		/* disk full or allocation exceeded */
#define	EBADOP		4		/* illegal TFTP operation */
#define	EBADID		5		/* unknown transfer ID */
#define	EEXISTS		6		/* file already exists */
#define	ENOUSER		7		/* no such user */

static const char tstr[] = " [|tftp]";

/* op code to string mapping */
static const struct tok op2str[] = {
	{ RRQ,		"RRQ" },	/* read request */
	{ WRQ,		"WRQ" },	/* write request */
	{ DATA,		"DATA" },	/* data packet */
	{ ACK,		"ACK" },	/* acknowledgement */
	{ TFTP_ERROR,	"ERROR" },	/* error code */
	{ OACK,		"OACK" },	/* option acknowledgement */
	{ 0,		NULL }
};

/* error code to string mapping */
static const struct tok err2str[] = {
	{ EUNDEF,	"EUNDEF" },	/* not defined */
	{ ENOTFOUND,	"ENOTFOUND" },	/* file not found */
	{ EACCESS,	"EACCESS" },	/* access violation */
	{ ENOSPACE,	"ENOSPACE" },	/* disk full or allocation exceeded */
	{ EBADOP,	"EBADOP" },	/* illegal TFTP operation */
	{ EBADID,	"EBADID" },	/* unknown transfer ID */
	{ EEXISTS,	"EEXISTS" },	/* file already exists */
	{ ENOUSER,	"ENOUSER" },	/* no such user */
	{ 0,		NULL }
};

/*
 * Print trivial file transfer program requests
 */
void
tftp_print(netdissect_options *ndo,
           register const u_char *bp, u_int length)
{
	register const struct tftphdr *tp;
	register const char *cp;
	register const u_char *p;
	register int opcode;
	u_int ui;

	tp = (const struct tftphdr *)bp;

	/* Print length */
	ND_PRINT((ndo, " %d", length));

	/* Print tftp request type */
	if (length < 2)
		goto trunc;
	ND_TCHECK(tp->th_opcode);
	opcode = EXTRACT_16BITS(&tp->th_opcode);
	cp = tok2str(op2str, "tftp-#%d", opcode);
	length -= 2;
	ND_PRINT((ndo, " %s", cp));
	/* Bail if bogus opcode */
	if (*cp == 't')
		return;

	switch (opcode) {

	case RRQ:
	case WRQ:
		p = (const u_char *)tp->th_stuff;
		if (length == 0)
			goto trunc;
		ND_PRINT((ndo, " "));
		/* Print filename */
		ND_PRINT((ndo, "\""));
		ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
		ND_PRINT((ndo, "\""));
		if (ui == 0)
			goto trunc;
		p += ui;
		length -= ui;

		/* Print the mode - RRQ and WRQ only */
		if (length == 0)
			goto trunc;	/* no mode */
		ND_PRINT((ndo, " "));
		ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
		if (ui == 0)
			goto trunc;
		p += ui;
		length -= ui;

		/* Print options, if any */
		while (length != 0) {
			ND_TCHECK(*p);
			if (*p != '\0')
				ND_PRINT((ndo, " "));
			ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
			if (ui == 0)
				goto trunc;
			p += ui;
			length -= ui;
		}
		break;

	case OACK:
		p = (const u_char *)tp->th_stuff;
		/* Print options */
		while (length != 0) {
			ND_TCHECK(*p);
			if (*p != '\0')
				ND_PRINT((ndo, " "));
			ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
			if (ui == 0)
				goto trunc;
			p += ui;
			length -= ui;
		}
		break;

	case ACK:
	case DATA:
		if (length < 2)
			goto trunc;	/* no block number */
		ND_TCHECK(tp->th_block);
		ND_PRINT((ndo, " block %d", EXTRACT_16BITS(&tp->th_block)));
		break;

	case TFTP_ERROR:
		/* Print error code string */
		if (length < 2)
			goto trunc;	/* no error code */
		ND_TCHECK(tp->th_code);
		ND_PRINT((ndo, " %s", tok2str(err2str, "tftp-err-#%d \"",
				       EXTRACT_16BITS(&tp->th_code))));
		length -= 2;
		/* Print error message string */
		if (length == 0)
			goto trunc;	/* no error message */
		ND_PRINT((ndo, " \""));
		ui = fn_printztn(ndo, (const u_char *)tp->th_data, length, ndo->ndo_snapend);
		ND_PRINT((ndo, "\""));
		if (ui == 0)
			goto trunc;
		break;

	default:
		/* We shouldn't get here */
		ND_PRINT((ndo, "(unknown #%d)", opcode));
		break;
	}
	return;
trunc:
	ND_PRINT((ndo, "%s", tstr));
	return;
}