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  * Format and print trivial file transfer protocol packets.
  22  */
  23
  24 /* \summary: Trivial File Transfer Protocol (TFTP) printer */
  25
  26 #ifdef HAVE_CONFIG_H
  27 #include "config.h"
  28 #endif
  29
  30 #include <netdissect-stdinc.h>
  31
  32 #include <string.h>
  33
  34 #include "netdissect.h"
  35 #include "extract.h"
  36
  37 /*
  38  * Trivial File Transfer Protocol (IEN-133)
  39  */
  40
  41 /*
  42  * Packet types.
  43  */
  44 #define RRQ     01                      /* read request */
  45 #define WRQ     02                      /* write request */
  46 #define DATA    03                      /* data packet */
  47 #define ACK     04                      /* acknowledgement */
  48 #define TFTP_ERROR      05                      /* error code */
  49 #define OACK    06                      /* option acknowledgement */
  50
  51 struct  tftphdr {
  52         unsigned short  th_opcode;              /* packet type */
  53         union {
  54                 unsigned short  tu_block;       /* block # */
  55                 unsigned short  tu_code;        /* error code */
  56                 char    tu_stuff[1];    /* request packet stuff */
  57         } th_u;
  58         char    th_data[1];             /* data or error string */
  59 };
  60
  61 #define th_block        th_u.tu_block
  62 #define th_code         th_u.tu_code
  63 #define th_stuff        th_u.tu_stuff
  64 #define th_msg          th_data
  65
  66 /*
  67  * Error codes.
  68  */
  69 #define EUNDEF          0               /* not defined */
  70 #define ENOTFOUND       1               /* file not found */
  71 #define EACCESS         2               /* access violation */
  72 #define ENOSPACE        3               /* disk full or allocation exceeded */
  73 #define EBADOP          4               /* illegal TFTP operation */
  74 #define EBADID          5               /* unknown transfer ID */
  75 #define EEXISTS         6               /* file already exists */
  76 #define ENOUSER         7               /* no such user */
  77
  78 static const char tstr[] = " [|tftp]";
  79
  80 /* op code to string mapping */
  81 static const struct tok op2str[] = {
  82         { RRQ,          "RRQ" },        /* read request */
  83         { WRQ,          "WRQ" },        /* write request */
  84         { DATA,         "DATA" },       /* data packet */
  85         { ACK,          "ACK" },        /* acknowledgement */
  86         { TFTP_ERROR,   "ERROR" },      /* error code */
  87         { OACK,         "OACK" },       /* option acknowledgement */
  88         { 0,            NULL }
  89 };
  90
  91 /* error code to string mapping */
  92 static const struct tok err2str[] = {
  93         { EUNDEF,       "EUNDEF" },     /* not defined */
  94         { ENOTFOUND,    "ENOTFOUND" },  /* file not found */
  95         { EACCESS,      "EACCESS" },    /* access violation */
  96         { ENOSPACE,     "ENOSPACE" },   /* disk full or allocation exceeded */
  97         { EBADOP,       "EBADOP" },     /* illegal TFTP operation */
  98         { EBADID,       "EBADID" },     /* unknown transfer ID */
  99         { EEXISTS,      "EEXISTS" },    /* file already exists */
 100         { ENOUSER,      "ENOUSER" },    /* no such user */
 101         { 0,            NULL }
 102 };
 103
 104 /*
 105  * Print trivial file transfer program requests
 106  */
 107 void
 108 tftp_print(netdissect_options *ndo,
 109            register const u_char *bp, u_int length)
 110 {
 111         register const struct tftphdr *tp;
 112         register const char *cp;
 113         register const u_char *p;
 114         register int opcode, i;
 115
 116         tp = (const struct tftphdr *)bp;
 117
 118         /* Print length */
 119         ND_PRINT((ndo, " %d", length));
 120
 121         /* Print tftp request type */
 122         ND_TCHECK(tp->th_opcode);
 123         opcode = EXTRACT_16BITS(&tp->th_opcode);
 124         cp = tok2str(op2str, "tftp-#%d", opcode);
 125         ND_PRINT((ndo, " %s", cp));
 126         /* Bail if bogus opcode */
 127         if (*cp == 't')
 128                 return;
 129
 130         switch (opcode) {
 131
 132         case RRQ:
 133         case WRQ:
 134         case OACK:
 135                 p = (const u_char *)tp->th_stuff;
 136                 ND_PRINT((ndo, " "));
 137                 /* Print filename or first option */
 138                 if (opcode != OACK)
 139                         ND_PRINT((ndo, "\""));
 140                 i = fn_print(ndo, p, ndo->ndo_snapend);
 141                 if (opcode != OACK)
 142                         ND_PRINT((ndo, "\""));
 143
 144                 /* Print the mode (RRQ and WRQ only) and any options */
 145                 while ((p = (const u_char *)strchr((const char *)p, '\0')) != NULL) {
 146                         if (length <= (u_int)(p - (const u_char *)&tp->th_block))
 147                                 break;
 148                         p++;
 149                         if (*p != '\0') {
 150                                 ND_PRINT((ndo, " "));
 151                                 fn_print(ndo, p, ndo->ndo_snapend);
 152                         }
 153                 }
 154
 155                 if (i)
 156                         goto trunc;
 157                 break;
 158
 159         case ACK:
 160         case DATA:
 161                 ND_TCHECK(tp->th_block);
 162                 ND_PRINT((ndo, " block %d", EXTRACT_16BITS(&tp->th_block)));
 163                 break;
 164
 165         case TFTP_ERROR:
 166                 /* Print error code string */
 167                 ND_TCHECK(tp->th_code);
 168                 ND_PRINT((ndo, " %s \"", tok2str(err2str, "tftp-err-#%d \"",
 169                                        EXTRACT_16BITS(&tp->th_code))));
 170                 /* Print error message string */
 171                 i = fn_print(ndo, (const u_char *)tp->th_data, ndo->ndo_snapend);
 172                 ND_PRINT((ndo, "\""));
 173                 if (i)
 174                         goto trunc;
 175                 break;
 176
 177         default:
 178                 /* We shouldn't get here */
 179                 ND_PRINT((ndo, "(unknown #%d)", opcode));
 180                 break;
 181         }
 182         return;
 183 trunc:
 184         ND_PRINT((ndo, "%s", tstr));
 185         return;
 186 }