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 #include <config.h>
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #include "netdissect.h"
  29 #include "extract.h"
  30
  31 /*
  32  * Trivial File Transfer Protocol (IEN-133)
  33  */
  34
  35 /*
  36  * Packet types.
  37  */
  38 #define RRQ     01                      /* read request */
  39 #define WRQ     02                      /* write request */
  40 #define DATA    03                      /* data packet */
  41 #define ACK     04                      /* acknowledgement */
  42 #define TFTP_ERROR      05                      /* error code */
  43 #define OACK    06                      /* option acknowledgement */
  44
  45 /*
  46  * Error codes.
  47  */
  48 #define EUNDEF          0               /* not defined */
  49 #define ENOTFOUND       1               /* file not found */
  50 #define EACCESS         2               /* access violation */
  51 #define ENOSPACE        3               /* disk full or allocation exceeded */
  52 #define EBADOP          4               /* illegal TFTP operation */
  53 #define EBADID          5               /* unknown transfer ID */
  54 #define EEXISTS         6               /* file already exists */
  55 #define ENOUSER         7               /* no such user */
  56
  57
  58 /* op code to string mapping */
  59 static const struct tok op2str[] = {
  60         { RRQ,          "RRQ" },        /* read request */
  61         { WRQ,          "WRQ" },        /* write request */
  62         { DATA,         "DATA" },       /* data packet */
  63         { ACK,          "ACK" },        /* acknowledgement */
  64         { TFTP_ERROR,   "ERROR" },      /* error code */
  65         { OACK,         "OACK" },       /* option acknowledgement */
  66         { 0,            NULL }
  67 };
  68
  69 /* error code to string mapping */
  70 static const struct tok err2str[] = {
  71         { EUNDEF,       "EUNDEF" },     /* not defined */
  72         { ENOTFOUND,    "ENOTFOUND" },  /* file not found */
  73         { EACCESS,      "EACCESS" },    /* access violation */
  74         { ENOSPACE,     "ENOSPACE" },   /* disk full or allocation exceeded */
  75         { EBADOP,       "EBADOP" },     /* illegal TFTP operation */
  76         { EBADID,       "EBADID" },     /* unknown transfer ID */
  77         { EEXISTS,      "EEXISTS" },    /* file already exists */
  78         { ENOUSER,      "ENOUSER" },    /* no such user */
  79         { 0,            NULL }
  80 };
  81
  82 /*
  83  * Print trivial file transfer program requests
  84  */
  85 void
  86 tftp_print(netdissect_options *ndo,
  87            const u_char *bp, u_int length)
  88 {
  89         const char *cp;
  90         u_int opcode;
  91         u_int ui;
  92
  93         ndo->ndo_protocol = "tftp";
  94
  95         /* Print protocol */
  96         nd_print_protocol_caps(ndo);
  97         /* Print length */
  98         ND_PRINT(", length %u", length);
  99
 100         /* Print tftp request type */
 101         if (length < 2)
 102                 goto trunc;
 103         opcode = GET_BE_U_2(bp);
 104         cp = tok2str(op2str, "tftp-#%u", opcode);
 105         ND_PRINT(", %s", cp);
 106         /* Bail if bogus opcode */
 107         if (*cp == 't')
 108                 return;
 109         bp += 2;
 110         length -= 2;
 111
 112         switch (opcode) {
 113
 114         case RRQ:
 115         case WRQ:
 116                 if (length == 0)
 117                         goto trunc;
 118                 ND_PRINT(" ");
 119                 /* Print filename */
 120                 ND_PRINT("\"");
 121                 ui = nd_printztn(ndo, bp, length, ndo->ndo_snapend);
 122                 ND_PRINT("\"");
 123                 if (ui == 0)
 124                         goto trunc;
 125                 bp += ui;
 126                 length -= ui;
 127
 128                 /* Print the mode - RRQ and WRQ only */
 129                 if (length == 0)
 130                         goto trunc;     /* no mode */
 131                 ND_PRINT(" ");
 132                 ui = nd_printztn(ndo, bp, length, ndo->ndo_snapend);
 133                 if (ui == 0)
 134                         goto trunc;
 135                 bp += ui;
 136                 length -= ui;
 137
 138                 /* Print options, if any */
 139                 while (length != 0) {
 140                         if (GET_U_1(bp) != '\0')
 141                                 ND_PRINT(" ");
 142                         ui = nd_printztn(ndo, bp, length, ndo->ndo_snapend);
 143                         if (ui == 0)
 144                                 goto trunc;
 145                         bp += ui;
 146                         length -= ui;
 147                 }
 148                 break;
 149
 150         case OACK:
 151                 /* Print options */
 152                 while (length != 0) {
 153                         if (GET_U_1(bp) != '\0')
 154                                 ND_PRINT(" ");
 155                         ui = nd_printztn(ndo, bp, length, ndo->ndo_snapend);
 156                         if (ui == 0)
 157                                 goto trunc;
 158                         bp += ui;
 159                         length -= ui;
 160                 }
 161                 break;
 162
 163         case ACK:
 164         case DATA:
 165                 if (length < 2)
 166                         goto trunc;     /* no block number */
 167                 ND_PRINT(" block %u", GET_BE_U_2(bp));
 168                 break;
 169
 170         case TFTP_ERROR:
 171                 /* Print error code string */
 172                 if (length < 2)
 173                         goto trunc;     /* no error code */
 174                 ND_PRINT(" %s", tok2str(err2str, "tftp-err-#%u \"",
 175                                        GET_BE_U_2(bp)));
 176                 bp += 2;
 177                 length -= 2;
 178                 /* Print error message string */
 179                 if (length == 0)
 180                         goto trunc;     /* no error message */
 181                 ND_PRINT(" \"");
 182                 ui = nd_printztn(ndo, bp, length, ndo->ndo_snapend);
 183                 ND_PRINT("\"");
 184                 if (ui == 0)
 185                         goto trunc;
 186                 break;
 187
 188         default:
 189                 /* We shouldn't get here */
 190                 ND_PRINT("(unknown #%u)", opcode);
 191                 break;
 192         }
 193         return;
 194 trunc:
 195         nd_print_trunc(ndo);
 196 }