1 /*
2  * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that: (1) source code distributions
7  * retain the above copyright notice and this paragraph in its entirety, (2)
8  * distributions including binary code include the above copyright notice and
9  * this paragraph in its entirety in the documentation or other materials
10  * provided with the distribution, and (3) all advertising materials mentioning
11  * features or use of this software display the following acknowledgement:
12  * ``This product includes software developed by the University of California,
13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14  * the University nor the names of its contributors may be used to endorse
15  * or promote products derived from this software without specific prior
16  * written permission.
17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20  */
21 
22 /* \summary: Trivial File Transfer Protocol (TFTP) printer */
23 
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27 
28 #include <netdissect-stdinc.h>
29 
30 #include <string.h>
31 
32 #include "netdissect.h"
33 #include "extract.h"
34 
35 /*
36  * Trivial File Transfer Protocol (IEN-133)
37  */
38 
39 /*
40  * Packet types.
41  */
42 #define	RRQ	01			/* read request */
43 #define	WRQ	02			/* write request */
44 #define	DATA	03			/* data packet */
45 #define	ACK	04			/* acknowledgement */
46 #define	TFTP_ERROR	05			/* error code */
47 #define OACK	06			/* option acknowledgement */
48 
49 /*
50  * Error codes.
51  */
52 #define	EUNDEF		0		/* not defined */
53 #define	ENOTFOUND	1		/* file not found */
54 #define	EACCESS		2		/* access violation */
55 #define	ENOSPACE	3		/* disk full or allocation exceeded */
56 #define	EBADOP		4		/* illegal TFTP operation */
57 #define	EBADID		5		/* unknown transfer ID */
58 #define	EEXISTS		6		/* file already exists */
59 #define	ENOUSER		7		/* no such user */
60 
61 static const char tstr[] = " [|tftp]";
62 
63 /* op code to string mapping */
64 static const struct tok op2str[] = {
65 	{ RRQ,		"RRQ" },	/* read request */
66 	{ WRQ,		"WRQ" },	/* write request */
67 	{ DATA,		"DATA" },	/* data packet */
68 	{ ACK,		"ACK" },	/* acknowledgement */
69 	{ TFTP_ERROR,	"ERROR" },	/* error code */
70 	{ OACK,		"OACK" },	/* option acknowledgement */
71 	{ 0,		NULL }
72 };
73 
74 /* error code to string mapping */
75 static const struct tok err2str[] = {
76 	{ EUNDEF,	"EUNDEF" },	/* not defined */
77 	{ ENOTFOUND,	"ENOTFOUND" },	/* file not found */
78 	{ EACCESS,	"EACCESS" },	/* access violation */
79 	{ ENOSPACE,	"ENOSPACE" },	/* disk full or allocation exceeded */
80 	{ EBADOP,	"EBADOP" },	/* illegal TFTP operation */
81 	{ EBADID,	"EBADID" },	/* unknown transfer ID */
82 	{ EEXISTS,	"EEXISTS" },	/* file already exists */
83 	{ ENOUSER,	"ENOUSER" },	/* no such user */
84 	{ 0,		NULL }
85 };
86 
87 /*
88  * Print trivial file transfer program requests
89  */
90 void
tftp_print(netdissect_options * ndo,register const u_char * bp,u_int length)91 tftp_print(netdissect_options *ndo,
92            register const u_char *bp, u_int length)
93 {
94 	register const char *cp;
95 	register int opcode;
96 	u_int ui;
97 
98 	/* Print length */
99 	ND_PRINT((ndo, " %d", length));
100 
101 	/* Print tftp request type */
102 	if (length < 2)
103 		goto trunc;
104 	ND_TCHECK_16BITS(bp);
105 	opcode = EXTRACT_16BITS(bp);
106 	cp = tok2str(op2str, "tftp-#%d", opcode);
107 	ND_PRINT((ndo, " %s", cp));
108 	/* Bail if bogus opcode */
109 	if (*cp == 't')
110 		return;
111 	bp += 2;
112 	length -= 2;
113 
114 	switch (opcode) {
115 
116 	case RRQ:
117 	case WRQ:
118 		if (length == 0)
119 			goto trunc;
120 		ND_PRINT((ndo, " "));
121 		/* Print filename */
122 		ND_PRINT((ndo, "\""));
123 		ui = fn_printztn(ndo, bp, length, ndo->ndo_snapend);
124 		ND_PRINT((ndo, "\""));
125 		if (ui == 0)
126 			goto trunc;
127 		bp += ui;
128 		length -= ui;
129 
130 		/* Print the mode - RRQ and WRQ only */
131 		if (length == 0)
132 			goto trunc;	/* no mode */
133 		ND_PRINT((ndo, " "));
134 		ui = fn_printztn(ndo, bp, length, ndo->ndo_snapend);
135 		if (ui == 0)
136 			goto trunc;
137 		bp += ui;
138 		length -= ui;
139 
140 		/* Print options, if any */
141 		while (length != 0) {
142 			ND_TCHECK(*bp);
143 			if (*bp != '\0')
144 				ND_PRINT((ndo, " "));
145 			ui = fn_printztn(ndo, bp, length, ndo->ndo_snapend);
146 			if (ui == 0)
147 				goto trunc;
148 			bp += ui;
149 			length -= ui;
150 		}
151 		break;
152 
153 	case OACK:
154 		/* Print options */
155 		while (length != 0) {
156 			ND_TCHECK(*bp);
157 			if (*bp != '\0')
158 				ND_PRINT((ndo, " "));
159 			ui = fn_printztn(ndo, bp, length, ndo->ndo_snapend);
160 			if (ui == 0)
161 				goto trunc;
162 			bp += ui;
163 			length -= ui;
164 		}
165 		break;
166 
167 	case ACK:
168 	case DATA:
169 		if (length < 2)
170 			goto trunc;	/* no block number */
171 		ND_TCHECK_16BITS(bp);
172 		ND_PRINT((ndo, " block %d", EXTRACT_16BITS(bp)));
173 		break;
174 
175 	case TFTP_ERROR:
176 		/* Print error code string */
177 		if (length < 2)
178 			goto trunc;	/* no error code */
179 		ND_TCHECK_16BITS(bp);
180 		ND_PRINT((ndo, " %s", tok2str(err2str, "tftp-err-#%d \"",
181 				       EXTRACT_16BITS(bp))));
182 		bp += 2;
183 		length -= 2;
184 		/* Print error message string */
185 		if (length == 0)
186 			goto trunc;	/* no error message */
187 		ND_PRINT((ndo, " \""));
188 		ui = fn_printztn(ndo, bp, length, ndo->ndo_snapend);
189 		ND_PRINT((ndo, "\""));
190 		if (ui == 0)
191 			goto trunc;
192 		break;
193 
194 	default:
195 		/* We shouldn't get here */
196 		ND_PRINT((ndo, "(unknown #%d)", opcode));
197 		break;
198 	}
199 	return;
200 trunc:
201 	ND_PRINT((ndo, "%s", tstr));
202 	return;
203 }
204