The Tcpdump Group git mirrors - tcpdump/blob - print-tftp.c

   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 struct  tftphdr {
  50         unsigned short  th_opcode;              /* packet type */
  51         union {
  52                 unsigned short  tu_block;       /* block # */
  53                 unsigned short  tu_code;        /* error code */
  54                 char    tu_stuff[1];    /* request packet stuff */
  55         } th_u;
  56         char    th_data[1];             /* data or error string */
  57 };
  58
  59 #define th_block        th_u.tu_block
  60 #define th_code         th_u.tu_code
  61 #define th_stuff        th_u.tu_stuff
  62 #define th_msg          th_data
  63
  64 /*
  65  * Error codes.
  66  */
  67 #define EUNDEF          0               /* not defined */
  68 #define ENOTFOUND       1               /* file not found */
  69 #define EACCESS         2               /* access violation */
  70 #define ENOSPACE        3               /* disk full or allocation exceeded */
  71 #define EBADOP          4               /* illegal TFTP operation */
  72 #define EBADID          5               /* unknown transfer ID */
  73 #define EEXISTS         6               /* file already exists */
  74 #define ENOUSER         7               /* no such user */
  75
  76 static const char tstr[] = " [|tftp]";
  77
  78 /* op code to string mapping */
  79 static const struct tok op2str[] = {
  80         { RRQ,          "RRQ" },        /* read request */
  81         { WRQ,          "WRQ" },        /* write request */
  82         { DATA,         "DATA" },       /* data packet */
  83         { ACK,          "ACK" },        /* acknowledgement */
  84         { TFTP_ERROR,   "ERROR" },      /* error code */
  85         { OACK,         "OACK" },       /* option acknowledgement */
  86         { 0,            NULL }
  87 };
  88
  89 /* error code to string mapping */
  90 static const struct tok err2str[] = {
  91         { EUNDEF,       "EUNDEF" },     /* not defined */
  92         { ENOTFOUND,    "ENOTFOUND" },  /* file not found */
  93         { EACCESS,      "EACCESS" },    /* access violation */
  94         { ENOSPACE,     "ENOSPACE" },   /* disk full or allocation exceeded */
  95         { EBADOP,       "EBADOP" },     /* illegal TFTP operation */
  96         { EBADID,       "EBADID" },     /* unknown transfer ID */
  97         { EEXISTS,      "EEXISTS" },    /* file already exists */
  98         { ENOUSER,      "ENOUSER" },    /* no such user */
  99         { 0,            NULL }
 100 };
 101
 102 /*
 103  * Print trivial file transfer program requests
 104  */
 105 void
 106 tftp_print(netdissect_options *ndo,
 107            register const u_char *bp, u_int length)
 108 {
 109         register const struct tftphdr *tp;
 110         register const char *cp;
 111         register const u_char *p;
 112         register int opcode;
 113         u_int ui;
 114
 115         tp = (const struct tftphdr *)bp;
 116
 117         /* Print length */
 118         ND_PRINT((ndo, " %d", length));
 119
 120         /* Print tftp request type */
 121         if (length < 2)
 122                 goto trunc;
 123         ND_TCHECK(tp->th_opcode);
 124         opcode = EXTRACT_16BITS(&tp->th_opcode);
 125         cp = tok2str(op2str, "tftp-#%d", opcode);
 126         length -= 2;
 127         ND_PRINT((ndo, " %s", cp));
 128         /* Bail if bogus opcode */
 129         if (*cp == 't')
 130                 return;
 131
 132         switch (opcode) {
 133
 134         case RRQ:
 135         case WRQ:
 136                 p = (const u_char *)tp->th_stuff;
 137                 if (length == 0)
 138                         goto trunc;
 139                 ND_PRINT((ndo, " "));
 140                 /* Print filename */
 141                 ND_PRINT((ndo, "\""));
 142                 ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
 143                 ND_PRINT((ndo, "\""));
 144                 if (ui == 0)
 145                         goto trunc;
 146                 p += ui;
 147                 length -= ui;
 148
 149                 /* Print the mode - RRQ and WRQ only */
 150                 if (length == 0)
 151                         goto trunc;     /* no mode */
 152                 ND_PRINT((ndo, " "));
 153                 ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
 154                 if (ui == 0)
 155                         goto trunc;
 156                 p += ui;
 157                 length -= ui;
 158
 159                 /* Print options, if any */
 160                 while (length != 0) {
 161                         ND_TCHECK(*p);
 162                         if (*p != '\0')
 163                                 ND_PRINT((ndo, " "));
 164                         ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
 165                         if (ui == 0)
 166                                 goto trunc;
 167                         p += ui;
 168                         length -= ui;
 169                 }
 170                 break;
 171
 172         case OACK:
 173                 p = (const u_char *)tp->th_stuff;
 174                 /* Print options */
 175                 while (length != 0) {
 176                         ND_TCHECK(*p);
 177                         if (*p != '\0')
 178                                 ND_PRINT((ndo, " "));
 179                         ui = fn_printztn(ndo, p, length, ndo->ndo_snapend);
 180                         if (ui == 0)
 181                                 goto trunc;
 182                         p += ui;
 183                         length -= ui;
 184                 }
 185                 break;
 186
 187         case ACK:
 188         case DATA:
 189                 if (length < 2)
 190                         goto trunc;     /* no block number */
 191                 ND_TCHECK(tp->th_block);
 192                 ND_PRINT((ndo, " block %d", EXTRACT_16BITS(&tp->th_block)));
 193                 break;
 194
 195         case TFTP_ERROR:
 196                 /* Print error code string */
 197                 if (length < 2)
 198                         goto trunc;     /* no error code */
 199                 ND_TCHECK(tp->th_code);
 200                 ND_PRINT((ndo, " %s", tok2str(err2str, "tftp-err-#%d \"",
 201                                        EXTRACT_16BITS(&tp->th_code))));
 202                 length -= 2;
 203                 /* Print error message string */
 204                 if (length == 0)
 205                         goto trunc;     /* no error message */
 206                 ND_PRINT((ndo, " \""));
 207                 ui = fn_printztn(ndo, (const u_char *)tp->th_data, length, ndo->ndo_snapend);
 208                 ND_PRINT((ndo, "\""));
 209                 if (ui == 0)
 210                         goto trunc;
 211                 break;
 212
 213         default:
 214                 /* We shouldn't get here */
 215                 ND_PRINT((ndo, "(unknown #%d)", opcode));
 216                 break;
 217         }
 218         return;
 219 trunc:
 220         ND_PRINT((ndo, "%s", tstr));
 221         return;
 222 }